JP6668885B2 - Printing equipment - Google Patents

Description

  The present invention relates to a printing apparatus including a transport unit that transports a medium such as paper and a printing unit that prints on the transported medium.

  For example, in the printing apparatuses described in Patent Literatures 1 and 2, the trailing edge of the preceding medium fed earlier and the leading edge of the succeeding media fed next to the preceding medium are overlapped with a margin. There is disclosed a technique of continuous feeding in which after the printing operation of the last line of the preceding medium is completed, the preceding medium and the succeeding medium are transported to a position where the succeeding medium reaches the printing start position while maintaining the overlapping state. According to this technique, the standby time from the end of the printing operation of the last line of the preceding medium to the start of printing of the succeeding medium can be relatively shortened, and the printing throughput can be improved.

  By the way, in the printing apparatus described in Patent Document 1, the feeding of the succeeding medium is started with an interval between the trailing edge of the preceding medium and the leading edge of the succeeding medium, and the leading edge of the succeeding medium is detected by the sensor. Then, an overlapping operation (catch-up feeding operation) of causing the leading end to catch up to a position overlapping the rear end of the preceding medium at a feeding speed higher than the conveying speed of the preceding medium is started. The overlapping operation is performed until the leading end of the succeeding medium reaches a standby position (determination position) slightly upstream in the medium conveyance direction from the conveyance roller pair (conveyance nip portion).

JP 2015-168237 A JP 2010-271405 A

  By the way, in the printing apparatus described in Patent Document 1, the leading edge of the succeeding medium is slightly smaller in the transport direction than the transport roller pair (transport nip portion) due to the overlapping operation that is started when the sensor detects the leading edge of the subsequent medium. It is transported until it reaches the standby position on the upstream side. For controlling the motor that transports the succeeding medium to the standby position, for example, it is necessary to control the motor until the succeeding medium reaches the standby position based on the detection position of the sensor that has detected the leading end of the subsequent medium and started the overlapping operation. is there. In this case, the distance that the leading edge of the succeeding medium is transported until the leading edge of the succeeding medium reaches the standby position is relatively long due to the overlapping operation that is started after the sensor detects the leading edge of the succeeding medium. And the accuracy of the stop position of the succeeding medium at the standby position is reduced. If the accuracy of the stop position of the subsequent medium to the standby position is reduced, the standby position is set at a position at a long distance away from the pair of transport rollers, taking into account the variation in the accuracy of the stop position. It is necessary to set the minimum value of the overlapping amount slightly larger in consideration of the above. For this reason, when the preceding medium is in a state where the rear end is located near the upstream side of the transport roller pair, the frequency at which the minimum overlapping amount cannot be secured and the continuous feeding cannot be performed increases. There is a problem that the frequency of implementation is reduced. This problem is not limited to the control of the stop position of the stacking operation to the standby position, but is generally common to the case where the medium is stopped at the predetermined position in a predetermined operation that is started when the leading end of the medium is detected by the sensor. Further, the above problem is not limited to a serial type printing device, but also applies to a line type printing device.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing apparatus capable of increasing stop position accuracy for stopping a medium at a predetermined position in a predetermined operation that is started when a leading end of the medium is detected by a sensor.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A printing apparatus that solves the above-described problem has a transport unit that has a first roller that transports a medium and a second roller that is located downstream of the transport path of the medium than the first roller, and is transported by the transport unit. A printing unit that prints on the medium, a first sensor that detects that the leading end of the medium has separated from the first roller, and a position between the first sensor and the second roller on the transport path. A second sensor provided, and a control unit that controls the transport unit and the printing unit, wherein the control unit is configured to detect the medium transported by the transport unit from a detection position where the first sensor detects the medium. A first drive amount up to a detection position detected by the second sensor is measured, and a second drive amount for driving the transport unit from the detection position of the first sensor to a predetermined position based on the first drive amount is measured. To correct the rotation amount.

  According to this configuration, the first drive amount from the detection position at which the medium conveyed by the conveyance unit is detected by the first sensor to the detection position at which the medium is detected by the second sensor is measured, and the first drive amount is measured based on the first drive amount. The second drive amount when driving the transport unit from the detection position of the sensor to the predetermined position is corrected. As a result, when the medium is transported to the predetermined position with the corrected second drive amount, the stop position accuracy for stopping the medium at the predetermined position can be improved.

In the printing apparatus, it is preferable that the predetermined position is set to a position between the second sensor and a nip position of the second roller at which the medium is nipped.
According to this configuration, the driving amount from the first sensor to the predetermined position located on the upstream side of the transport path from the second roller based on the first driving amount between the detection positions of the first sensor and the second sensor. Is corrected. Therefore, the stop position accuracy when the medium is transported to the predetermined position can be improved.

  In the above-described printing apparatus, the control unit controls a subsequent medium, which is a medium conveyed next to a preceding medium, which is a medium conveyed first by the conveyance unit, to a feeding speed higher than the conveying speed of the preceding medium. And the overlapping operation of partially overlapping the preceding medium with the preceding medium, and until the succeeding medium reaches the printing start position while maintaining the overlapping state of the preceding medium and the succeeding medium after the printing of the preceding medium is completed. It is preferable that the predetermined position is a standby position where the succeeding medium is made to wait until the overlapping continuous feeding is started after the completion of the overlapping operation.

  According to this configuration, the first drive amount from the detection position at which the medium conveyed by the conveyance unit is detected by the first sensor to the detection position at which the medium is detected by the second sensor is measured, and the first drive amount is measured based on the first drive amount. The second drive amount when driving the transport unit from the detection position of the sensor to the standby position is corrected. Thereafter, an overlapping operation of feeding the succeeding medium at a feeding speed higher than the transport speed of the preceding medium and partially overlapping the preceding medium is performed. At this time, since the overlapping operation is performed with the corrected second drive amount, the accuracy of the stop position of the succeeding medium to the standby position, which is the target position of the overlapping operation, can be improved, and the frequency of the continuous continuous feeding can be increased. be able to.

  In the printing device, a storage unit that stores a third drive amount from a detection position of the second sensor to a position at which the second roller nips the medium, and the control unit performs continuous printing on a plurality of the media. When the first medium is conveyed, the first drive amount from the detection position of the first sensor to the detection position of the second sensor is measured when the first medium is transported, and the first drive amount and the third drive amount are measured. Preferably, the second drive amount is corrected based on the amount.

  According to this configuration, when performing continuous printing on a plurality of media, the first drive amount from the detection position of the first sensor to the detection position of the second sensor is measured when the first medium is transported, The second drive amount is corrected based on the first drive amount and the third drive amount.

  The printing apparatus further includes a position sensor that detects that the medium has reached the predetermined position, wherein the control unit controls the transport unit based on the corrected second drive amount to set the next and subsequent media. The medium is transported at a first transport speed to a set position upstream of the predetermined position, and the medium is transported from the set position to the predetermined position at a second transport speed lower than the first transport speed. It is preferable that the driving of the transport unit is stopped at a position where the medium is detected.

  According to this configuration, the medium following the medium used for the measurement is transported at the first transport speed to the set position by the control unit controlling the transport unit based on the corrected drive amount, and To a predetermined position at a second transport speed lower than the first transport speed. The drive of the transport unit is stopped at a position where the position sensor detects the medium during the transport at a low speed. As a result, the medium can be stopped at a predetermined position with relatively high positional accuracy.

  The printing apparatus further includes a gap sensor capable of detecting a gap between the preceding medium and the succeeding medium when the overlapping operation of the succeeding medium is completed, wherein the control unit moves the succeeding medium to the standby position. After stopping, when the gap sensor detects a gap between the preceding medium and the succeeding medium, it is preferable to stop the overlapping continuous feeding.

  According to this configuration, if the gap sensor detects a gap between the preceding medium and the succeeding medium after stopping the succeeding medium at the standby position, the overlapping continuous feeding is stopped. Therefore, when the stacking operation fails, the continuous stacking can be stopped. It is possible to avoid a situation in which the continuous feeding is improperly performed even though the preceding medium and the succeeding medium are not properly overlapped.

FIG. 1 is a perspective view illustrating a multifunction peripheral including a printing apparatus according to an embodiment. FIG. 2 is a side sectional view showing the multifunction peripheral. FIG. 2 is a side sectional view illustrating a main part of the printing apparatus. FIG. 2 is a schematic plan view showing the inside of the printing apparatus. FIG. 4 is a side view illustrating a transport mechanism and a printing unit. FIG. 3 is a schematic bottom view illustrating a nozzle opening surface and a discharge unit in the print head. FIG. 2 is a block diagram illustrating an electrical configuration of the printing apparatus. 5 is a timing chart showing the operation of various motors when performing continuous feeding. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 4 is a side view showing a part of a transport mechanism for explaining a stackable condition. FIG. 5 is a side view illustrating continuous over-feeding by the transport mechanism according to the first embodiment. FIG. 8 is a side view of the transport mechanism for explaining a second overlapping continuous feeding execution condition. 7 is a timing chart showing the operation of various motors when a second overlap continuous feeding execution condition is satisfied. 9 is a timing chart showing the operation of various motors when the second continuous feeding execution condition is not satisfied. 9 is a flowchart illustrating a conveyance control including the continuous feeding. 5 is a timing chart showing the operation of various motors when performing continuous feeding in 2 of the first embodiment. 9 is a flowchart illustrating a conveyance control including the continuous feeding. 9 is a flowchart illustrating conveyance control including overlapped continuous feeding in 3 of the first embodiment. FIG. 13 is a schematic side view illustrating a printing step of printing a first line in a first mode according to a second embodiment. FIG. 7 is a schematic side view illustrating a printing step of printing the last line in a first mode. FIG. 9 is a schematic side view illustrating a printing process of printing the last line based on a nozzle change. 9 is a flowchart illustrating printing control in the overlap feeding method. FIG. 13 is a schematic side view showing a printing step of printing the last line using the most upstream nozzle in a modified example. FIG. 9 is a schematic side view illustrating a printing process of printing the first line using the most upstream nozzle. FIG. 9 is a schematic side view showing a printing step for printing the last line. FIG. 13 is a schematic side view illustrating bidirectional printing according to the third embodiment. FIG. 4 is a schematic plan view illustrating bidirectional printing on a medium after continuous feeding. FIG. 4 is a schematic side view illustrating printing on a preceding medium. FIG. 9 is a schematic side view illustrating printing on a subsequent medium after continuous feeding. FIG. 4 is a schematic side view showing a state in which printing is performed on a subsequent medium after continuous feeding. FIG. 4 is a schematic side view illustrating a avoidance process in bidirectional printing. FIG. 9 is a schematic side view illustrating printing on a subsequent medium after continuous feeding. FIG. 9 is a schematic side view illustrating printing on a subsequent medium after continuous feeding. FIG. 4 is a schematic side view illustrating a printing failure caused by head rubbing caused by continuous feeding. 5 is a graph showing a superimposition permitted area. 9 is a flowchart illustrating a print control routine in the overlap feeding method. 13 is a flowchart illustrating a print control routine in the overlap feeding method according to the second embodiment of the present invention. FIG. 14 is a schematic side view illustrating a transport mechanism and a printing unit according to a fourth embodiment. FIG. 42 is a sectional view taken along line AA in FIG. 41 illustrating a configuration of a guide member. FIG. 42 is a sectional view taken along the line BB in FIG. 41 illustrating an arrangement configuration of the third sensor. FIG. 9 is a schematic side view illustrating a state in which a third sensor detects a succeeding medium during an overlapping operation. 6 is a timing chart showing the operation of each motor and the detection state of each sensor during the overlap feeding. 6 is a timing chart when a superposition operation fails. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 9 is a side view showing a state when the superposing operation of the succeeding medium is started. FIG. 6 is a side view showing the succeeding medium during the overlapping operation. FIG. 4 is a side view showing a state in which the overlapping operation has been completed. FIG. 9 is a side view illustrating a skew removing operation of a subsequent medium. FIG. 9 is a flowchart illustrating a print control routine in the overlap feeding method. FIG. 14 is a schematic side view illustrating a lower stacking operation in 2 of the fourth embodiment. FIG. 6 is a schematic side view illustrating a lower stacking operation. FIG. 4 is a schematic side view when a lower stacking operation has failed. FIG. 15 is a side view showing a transport mechanism and a printing unit according to the fifth embodiment. 9 is a flowchart illustrating a print control routine in the overlap feeding method. The schematic side view which shows the 4th sensor in 2 of 5th Embodiment. The schematic side view which shows the 4th sensor different from FIG. 58. The schematic side view which shows a 5th sensor. 9 is a flowchart illustrating a superposition operation control routine. FIG. 14 is a schematic plan view showing the inside of a printing apparatus according to a sixth embodiment. FIG. 4 is a side view illustrating a transport mechanism and a printing unit. FIG. 9 is a schematic side view illustrating the operation of the flap member and the lower path member. FIG. 4 is a schematic side cross-sectional view illustrating a configuration of a lower path member. FIG. 2 is a block diagram illustrating an electrical configuration of the printing apparatus. 6 is a timing chart showing the operation of each motor and each solenoid when performing the overlap feeding. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. FIG. 5 is a side view for explaining a feeding operation of the preceding medium by the transport mechanism. 9 is a flowchart illustrating a print control routine in the overlap feeding method. FIG. 17 is a side view showing a transport mechanism and a printing unit according to a second embodiment of the sixth embodiment. FIG. 15 is a side view illustrating a transport mechanism and a printing unit according to a third embodiment of the invention. FIG. 16 is a side view showing a transport mechanism and a printing unit according to a fourth embodiment of the invention. FIG. 4 is a side view showing the transport mechanism and the printing unit. FIG. 16 is a side view showing a transport mechanism and a printing unit according to a fifth embodiment of the invention. FIG. 4 is a side view showing the transport mechanism and the printing unit. FIG. 9 is a schematic side cross-sectional view illustrating a configuration of a lower path member according to a modification. FIG. 3 is a schematic side cross-sectional view showing a multifunction peripheral provided with a printing apparatus having a separation method different from that of FIG. 2.

  Hereinafter, a multifunction peripheral including a printing apparatus will be described with reference to the drawings. In the following, the direction in which the printing unit moves during printing is referred to as the “scanning direction X (width direction X)”, the direction in which the medium is conveyed at a location facing the printing unit is referred to as the “transport direction Y”, and the direction below the vertical direction. The direction toward the side is referred to as “gravity direction Z”.

  As shown in FIG. 1, the multifunction peripheral 11 includes a printing device 12 having a printing function, an image reading device 13 having an image reading function, and an automatic document feeder 14 for feeding a document to the image reading device 13. Prepare. The printing device 12 includes a main body 15 having a rectangular parallelepiped shape, and a main body cover 151 that can be opened and closed with respect to an upper opening (not shown) of the main body 15. The image reading device 13 is rotatably opened and closed with respect to a scanner main body 131 having a main body lid portion 151 having a built-in reading mechanism and a document table 132 (see FIG. 2) constituting an upper surface portion of the scanner main body 131. And a lid portion 133 that performs the operation. The automatic document feeder 14 is assembled on the lid 133 and is rotatable in the opening and closing direction together with the lid 133. The cover 133 is movable together with the automatic document feeder 14 between a closed position covering the document table 132 and an open position where the document table 132 is exposed so that a document can be placed.

  In addition, a concave grip 152 is provided on the front side of the main body cover 151 (downstream in the transport direction Y). The user grips the gripper 152 and lifts it upward, and rotates the main body cover 151 in the opening direction together with the image reading device 13 and the automatic document feeder 14 so that the main body cover 151 moves from the closed position shown in FIG. Is arranged at an open position (not shown) in which the upper part of the is opened. When the main body cover 151 is in the open position, the printing mechanism in the housing 153 that constitutes the main body 15 is exposed, and the user replaces the ink container 39 (see FIG. 3) such as an ink cartridge and removes the medium jam. Maintenance work including removal work is possible.

  The automatic document feeder 14 shown in FIG. 1 includes a document table 141 on which a plurality of documents can be set, and a pair of document edges operated when positioning the document set on the document table 141 in the width direction. The document includes a guide 142 and a document support 143 capable of supporting a portion of the document protruding from the document table 141.

  On the lower side of the document table 141, there is provided a document discharge section 144 for discharging a document fed by the automatic document feeder 14 after being scanned by the image reading device 13. The automatic document feeder 14 is disposed opposite to a pair of wall portions 145 disposed on both sides of the document table 141 in a direction intersecting the document transport direction and a discharge port of the document discharge section 144. And a side plate 146. For this reason, the document discharge section 144 is surrounded by a pair of walls 145, a document table 141, and a side plate 146. The side plate 146 is provided with a concave portion 147 for the user to check the document discharged to the document discharge portion 144. For this reason, the document discharged to the document discharge section 144 through the concave portion 147 can be confirmed, and the discharged document can be picked up from the concave portion 147. The document support 143 may be a transparent member. By using a transparent member, even when a small-sized document (for example, A6 size) is scanned by using the automatic document feeder 14, the small-sized document is transferred to the document discharge unit 144 through the document support 143. It can be confirmed that the document has been ejected, so that it is possible to prevent the document from being forgotten.

  As shown in FIG. 1, a rectangular plate-shaped operation panel 16 having a power button 17 and a display unit 18 of a touch panel type is provided at an upper part of the front surface of the printing apparatus 12. The operation panel 16 further includes an operation button 161, a power LED 162, a FAX reception LED 163, a print job reception LED 164, and an error notification LED 165. The operation button 161 functions as a cancel button during execution of printing, and functions as a copy button during printing standby. When the operation button 161 is operated as a copy button and the sensor (not shown) detects that a document is placed on the document placing table 141, the automatic document feeder 14 is driven to drive the fed document. Is scanned. On the other hand, when the original is not placed on the original placing table 141 while the sensor is not detected, the original placed on the original placing table 132 is scanned. The main body 15 is provided with a lid 154 of a USB slot (not shown) beside the operation panel 16.

  Further, on the lower side of the operation panel 16 of the printing device 12, an outlet 19 for discharging the printed medium P and a slide-type discharge stacker 20 for receiving the medium P discharged from the outlet 19 are provided. I have. The discharge stacker 20 can be manually slid between a storage position shown in FIG. 1 and a deployed position shown in FIG. Further, below the discharge stacker 20 in the housing 153 of the main body 15, there is provided a cassette housing portion 155 formed of a housing space which is open at the front surface and extends backward. Upper and lower two-stage cassettes 21 and 22 capable of accommodating a plurality of media P are mounted in the cassette accommodating portion 155 so as to be insertable and removable. At the bottom of both sides of the main body 15, there is provided a concave handle 156 (only one is shown in FIG. 1) that can be gripped when the user lifts the multifunction device 11.

  Next, with reference to FIGS. 2 and 3, an internal configuration of the MFP 11, particularly, the printing apparatus 12 will be described. As shown in FIG. 2, a housing 153 accommodates a transport mechanism 24 that transports the medium P and a printing unit 25 that prints on the transported medium P. The transport mechanism 24 includes a feeding mechanism 26 that feeds the media P in the cassettes 21 and 22 to the printing unit 25 one by one. The feeding mechanism 26 is provided at an end of the arm member 27 that is rotatably supported on a base end at a position corresponding to an insertion portion of each of the cassettes 21 and 22 in the main body 15. Feeding roller 28 (pickup roller) provided. In the following, when the feeding roller 28 is distinguished between the first cassette 21 side and the second cassette 22 side, the feeding roller 28 on the first cassette 21 side is denoted by reference numeral 281 and the feeding roller 28 on the second cassette 22 side. The feed roller 28 is indicated by reference numeral 282.

  Further, the cassettes 21 and 22 are provided with side edge guides 211 and 221 capable of positioning the medium P in the width direction by abutting on the side edges on both sides of the loaded (set) medium P in the width direction, and feeding the medium P. Edge guides 212 and 222 capable of positioning the rear end by contacting the upstream end (rear end) in the direction, and positioning the front end by contacting the downstream end (tip) of the medium P in the feeding direction. And a possible not-shown claw portion. The medium P set in the cassettes 21 and 22 is held by the cassettes 21 and 22 by the tip of the medium P hitting the claws. Note that the claw portion is arranged at a position where it does not contact the feed roller 28 in the process of inserting the cassettes 21 and 22.

  The arm member 27 is urged clockwise in FIG. 2 by a spring (not shown) in a state where the cassettes 21 and 22 are not inserted into the cassette accommodating portion 155. When the cassettes 21 and 22 are inserted into the cassette accommodating portion 155, the arm member 27 releases the bias of the spring by the cassettes 21 and 22, rotates clockwise by its own weight, and the feed roller 28 The uppermost one of the plurality of media P in the cassette 22 contacts the medium P.

  As shown in FIG. 2, the back of the cassette accommodating portion 155 in the main body 15 (to the right in FIG. 2) is inclined at a position facing the end of the cassette 21 and 22 in the feeding direction (to the right in FIG. 2). Separating plates 157 and 158 (separating wall portions) are arranged respectively. Even if a plurality of media P are sent out by the feeding roller 28, only the uppermost one is separated and is fed to the downstream side in the feeding direction by sliding on the surfaces of the separation plates 157 and 158. You. As described above, in the present embodiment, the wall separation method is employed as the separation method for separating the medium P into one sheet. Note that, instead of the wall separation method, a roller separation method in which the medium P is separated into one by passing the medium P between a pair of separation rollers may be adopted.

  Further, as shown in FIG. 2, the feeding mechanism 26 has transport passages 261 and 262 through which the medium P sent out from each of the cassettes 21 and 22 is transported via the separation plates 157 and 158. The two transfer passages 261 and 262 join at a position above the separation plate 157 on the upper cassette 21 side. Hereinafter, the upper (first) cassette 21 is also referred to as a “first cassette 21”, and the lower (second) cassette 22 is also referred to as a “second cassette 22”.

  As shown in FIG. 2, the transport path 262 through which the medium P is transported from the lower second cassette 22 located below the upper first cassette 21 is moved in the depth direction (in order to avoid the first cassette 21). (Right direction in the figure). In the first cassette 21 and the second cassette 22, the front end portions 213 and 223 on the take-out side are flush, but the rear end edge guide 222, the feeding roller 282, and the separation plate 158 corresponding to the second cassette 22 are , The rear edge guide 212, the feed roller 281, and the separation plate 157 corresponding to the first cassette 21, respectively, are offset in the depth direction.

  As shown in FIG. 2, the feeding mechanism 26 includes a large-diameter intermediate roller 30 disposed obliquely above the junction 263 (see FIG. 3) of the two transport passages 261 and 262, and an intermediate roller 30. And a first driven roller 31 and a second driven roller 32 having a small diameter and contacting the outer peripheral surface of the first driven roller 31. The medium P sent from one of the cassettes 21 and 22 reaches the junction 263 through the corresponding one of the transport passages 261 and 262, and the intermediate roller 30 is rotated by the rotation of the intermediate roller 30 from the junction 263. While being nipped (nipped) between the intermediate roller 30 and the two driven rollers 31 and 32, the sheet is conveyed along a path along the outer periphery of the intermediate roller 30. Then, the medium P is sent out from the nip between the intermediate roller 30 and the second driven roller 32 toward the transport roller pair 33.

  As shown in FIGS. 2 and 3, the medium P sent from the nip portion is guided to a position immediately downstream of the nip portion between the intermediate roller 30 and the second driven roller 32 in the transport direction Y. A guide member 55 for changing the sending direction to the target direction is arranged. At the time of feeding the medium P, the medium P sent out from the nip portion between the intermediate roller 30 and the second driven roller 32 is guided along the upper surface of the guide member 55 to the downstream side in a substantially horizontal direction, and the inclined ceiling is formed. After reaching the wall portion 56, it is conveyed along a diagonally downward path along the oblique surface of the ceiling wall portion 56 while maintaining the upper limit height. Further, between the intermediate roller 30 and the transport roller pair 33, when the fed medium P is in a state of hanging from the guide member 55, the medium P supports the hanging part, or after the medium P falls from the guide member 55. A support member 57 that supports the rear end of the medium P is disposed.

  As shown in FIG. 3, the support member 57 has a concave curved surface in which the upstream portion in the transport direction Y on the upper surface supporting the medium P becomes lower toward the downstream side, and the downstream portion in the transport direction Y is lower than the concave curved portion. The side portion is a flat surface extending substantially horizontally. The support member 57 has a protruding end 57E at the downstream end in the transport direction Y. The protruding end 57E of the supporting member 57 includes a feeding path that forms a lower path for guiding the medium P fed from the cassettes 21 and 22 to the pair of conveying rollers 33, and a conveying roller that is printed on one surface (one side). It is a diverging point from the reversing path 40 that guides the medium P to be subjected to double-sided printing conveyed backward from the pair 33 to the intermediate roller 30.

  As shown in FIGS. 2 and 3, the transport mechanism 24 includes a transport roller pair 33 that transports the medium P fed from the feed mechanism 26 along a path that passes through a print area where the printing unit 25 can print. The unit 25 includes a discharge roller pair 34 that discharges the printed medium P. At a position slightly upstream in the transport direction Y with respect to the transport roller pair 33, a long swinging member 58 is obliquely shown in FIG. It is arranged in a state of a standby posture in which it is inclined. The swing member 58 has a holding rib 581 and a flap 582 that protrude downward. The holding rib 581 has a function of urging the rear end of the medium P downward to suppress the rising of the rear end of the medium P.

  Here, the protruding end portion of the holding rib 581 that can contact the medium P is offset downward (gravity direction Z) below an imaginary line connecting the nip position of the transport roller pair 33 and the protruding end portion 57E of the support member 57. Is located. Ideally, the protruding end of the holding rib 581 is located on the above-mentioned imaginary line. However, in consideration of manufacturing tolerances, in order to avoid the inconvenience when it is shifted upward from the above-mentioned imaginary line, the swing member With the spring load of 58 pressing the holding rib 581 downward, the protruding end of the holding rib 581 is offset downward from the imaginary line.

  As shown in FIGS. 2 and 3, at a position between the transport roller pair 33 and the discharge roller pair 34 in the transport direction Y, a support table 35 capable of supporting the medium P transported along the transport path is provided. Is arranged. The transport roller pair 33 includes a transport drive roller 33A and a transport driven roller 33B that is rotatable following the rotation of the transport drive roller 33A. The discharge roller pair 34 includes a discharge drive roller 34A and a discharge driven roller 34B that can rotate in accordance with the rotation of the discharge drive roller 34A. At a position between the discharge roller pair 34 and the support base 35 in the transport direction Y, a pressing roller 34C that presses the leading end of the medium P before being nipped by the discharge roller pair 34 from above to prevent the medium P from floating. Is provided.

  As shown in FIGS. 2 and 3, the printing unit 25 includes a carriage 36, which is guided by a guide rail unit 37 and is reciprocally movable in the scanning direction X and held at a position above the support base 35. And a print head 38 attached to the surface opposite to the support base 35. The carriage 36 is supported at two places by, for example, a pair of upper and lower guide rails 37, and is guided in a state where it can be moved in the scanning direction X while being positioned in the transport direction Y and the gravity direction Z. A plurality of ink containers 39 of the same number as the ink colors are mounted on the upper portion of the carriage 36. The print head 38 discharges the ink supplied from the ink container 39 mounted on the upper portion of the carriage 36 toward the medium P in the process of moving in the scanning direction X. Therefore, each time the medium P intermittently conveyed during printing stops, printing is performed line by line by the print head 38. The printed medium P is discharged from the discharge port 19 by rotation of the discharge roller pair 34 and the like, and is stacked on the discharge stacker 20. The user stacks the discharge stacker 20 from the storage position shown in FIG. 1 in the transport direction Y to protrude, and then rotates the distal end portion, whereby the discharge stacker 20 is developed into the state of use shown in FIG. The ink container 39 of the present embodiment is configured by an ink cartridge. The ink container 39 is supplied with ink from an ink tank attached to the inside or outside of the main body 15 through an ink tube (neither is shown). May be an adapter that can temporarily store.

  Further, the printing apparatus 12 of the present example has a double-sided printing function. In the main body 15, the reversing passage 40 (in which the medium P conveyed in the conveyance direction Y and printed on one surface (one side) by the printing unit 25 is reversely conveyed in the opposite direction to the conveyance direction Y and guided to the merging unit 263 ( Switchback passage) is provided. The reversing passage 40 extends along a path that passes below the support member 57, and merges with the junction 263 of each of the transport passages 261 and 262. The medium P on which printing on one surface (front surface) has been completed is reversely conveyed along the conveyance path F3 passing through the reversing path 40 and reaches the junction 263. From the junction 263, the intermediate roller 30 and the first driven roller Introduced to the nip with 31. Specifically, when the medium P passes through the reversing passage 40, the flap portion 582 guides the medium P at the time of switchback to the lower side and guides the medium P to the reversing passage 40. When the leading end of the medium P touches the flap portion 582 from the upstream side to the downstream side, the medium P is not regulated because the flap portion 582 rotates toward the downstream side in the transport direction Y. On the other hand, when the medium P is switched back for printing on the other side (back side), the medium P is not rotated even when the leading end of the medium P touches the flap portion 582 from the downstream side to the upstream side, and the medium P is switched back. The medium P is guided to the reverse passage 40.

  Then, the medium P is turned upside down in the process of being conveyed along the outer periphery of the intermediate roller 30, and is passed through the conveying roller pair 33 so that the other surface faces the print head 38 and the printing unit 25. Then, by printing on the other surface (back surface) of the medium P by the printing unit 25, double-sided printing is performed on the medium P. The medium P that has been subjected to double-sided printing is stacked on the discharge stacker 20.

  Further, as shown in FIG. 2, the image reading device 13 is a flat-bed type scanner device, and a document table 132 having a document placing glass plate 134 and a position below the document placing glass plate 134 are moved in the scanning direction X. And a scanner carriage 135 that can reciprocate along. Further, as shown in FIGS. 2 and 3, a power supply unit 59 is provided in the main body 15 at a position higher than the transport path. The power supply unit 59 converts power from, for example, a commercial AC power supply to DC and supplies power necessary for driving to the printing apparatus 12, the image reading apparatus 13, and the automatic document feeder 14.

  As illustrated in FIG. 2, a remaining amount sensor 201 that detects the remaining amount of ink in the ink container 39 is provided at a position downstream of the support base 35 in the transport direction Y in the main body 15. One remaining amount sensor 201 is arranged at a predetermined position in the scanning direction X. In the carriage 36, a plurality of holes 361 to be detected are opened at a position facing the remaining amount sensor 201 in a state of being arranged in a line in the scanning direction X. The ink from each ink container 39 is supplied to the print head 38 via the upper side of the hole 361 for detection. When the hole 361 is located above the remaining amount sensor 201 with the movement of the carriage 36 in the scanning direction X, the remaining amount sensor 201 detects ink from the ink container 39 corresponding to the hole 361 through the hole 361. If there is ink, a non-detection state is set, and if ink runs out, a detection state is set. The plurality of holes 361 need to be arranged in a line along the scanning direction X in order to be detected by the remaining amount sensor 201. The adjustment dial 202 shown in FIG. 3 is provided on the carriage 36, and by operating the adjustment dial 202, the carriage 36 can be rotated around the axis in the direction of gravity Z to adjust the attitude angle thereof. Has become. By adjusting the attitude angle of the carriage 36, all of the plurality of holes 361 can be arranged in a line along the scanning direction X that can be detected by the remaining amount sensor 201.

  In the printing device 12 of the present embodiment, one of a plurality of types of feeding methods is selected according to printing conditions based on a print job. When the printing device 12 receives a print job of plain paper, band printing, and single-sided printing, the printing start position of the succeeding medium P is maintained while partially overlapping the preceding medium P and the succeeding medium P. Select the nested feeding method with nested feeding that transports the sheets together. When the printing apparatus 12 receives a print job of other printing conditions, the normal feeding method of conveying the succeeding medium P to the printing start position with the preceding medium P and the succeeding medium P spaced apart from each other. Select When the overlap feeding method is selected, an overlapping operation in which the leading end of the succeeding medium, which is the medium P transported next to the preceding medium, is overlapped on the trailing end of the preceding medium, which is the medium P transported earlier. After that, when the printing of the preceding medium is finished, the continuous feeding is performed in which the preceding medium and the succeeding medium are conveyed together to the printing start position of the succeeding medium while maintaining the overlapping state at that time. Further, after the overlapping operation and before the continuous feeding, a skew removing operation for correcting the skew (skew) of the subsequent medium by abutting the leading end of the succeeding medium on the transport roller pair 33 is performed. In addition, even when the overlapping feeding method is selected, the overlapping continuous feeding is performed only when a later-described overlapping enabled condition regarding the preceding medium and the succeeding medium is satisfied.

  Further, in the overlapping method in the overlapping operation, an upper overlap in which the leading end of the succeeding medium is placed above the trailing end of the preceding medium, and a lower overlap in which the leading end of the succeeding medium is placed below the trailing end of the preceding medium. There is. The stacking operation according to the present embodiment is performed in an upper stack. Therefore, it is necessary to overlap the leading end of the succeeding medium above the trailing end of the preceding medium. Therefore, the guide member 55 overlaps the feeding direction of the medium P sent from the nip portion between the intermediate roller 30 and the second driven roller 32 so that the preceding medium and the following medium overlap in the correct stacking order in the stacking operation. Change the guide direction to the upper side, which is easier. The medium P sent out from the final nip of the intermediate roller 30 at a predetermined feeding speed is changed along the upper surface of the guide member 55 to a substantially horizontal upper direction, and is sent out in a substantially horizontal direction. The medium P is transported toward the transport roller pair 33 while maintaining the upper limit position along the inclined surface of the ceiling wall portion 56. As a result, the superimposition of the succeeding medium from the upper side (printing surface side) on the preceding medium succeeds with higher frequency.

  The guide member 55 shown in FIG. 3 may be fixed in a posture (for example, a horizontal posture) capable of guiding the medium P in the feeding direction at the time of the stacking operation, but when the stacking operation is not performed, the feeding direction is shifted upward. It is not preferable to apply a resistive load to the medium P being transported when changing to. Therefore, a guiding position (first position, which is the position shown in FIG. 3) in which the guiding member 55 takes a position to guide the medium P during the overlapping operation, and a position or a guiding position in which the medium P is not guided in other than the overlapping operation. It is preferable that the medium P be displaceably provided between a retracted position (a second position) and a retracted position (a second position) in which the load on the medium P is reduced.

  When the guide member 55 is provided so as to be displaceable, the following two kinds of displacement directions are available. First, the guide position of the guide member 55 is common to the two types. The guide member 55 makes it possible to fly the medium P as much as possible on the downstream side and the horizontal direction in the transport direction Y as much as possible, and to easily overlap the succeeding medium on the preceding medium. The guide position is set to take a posture (for example, a horizontal posture). One is a rotation method in which the guide member 55 is rotated between an evacuation position in which the guide member 55 takes an obliquely downward posture with its upstream end as a fulcrum, and the above-described guide position. The other one is the same as the rotary type in the guide position, in which the guide member 55 projects in the path in a horizontal position, and in the retracted position, the position is in the horizontal position but the guide member 55 does not project in the path. And a slide method in which the slide movement is performed in the horizontal direction (transfer direction Y) between the retreat position and the guide position.

  Further, the mechanism for displacing the guide member 55 holds the guide member 55 at the guide position by the urging force (spring load) of the spring. System. For example, in the case of a medium P made of thick paper such as photo paper, the amount of displacement when the guide member 55 is displaced to the retracted position due to stiffness of the medium P is relatively large, and in the case of a medium P made of thin paper such as plain paper. Since the stiffness of the medium P is weak, the amount of displacement when the guide member 55 is retracted is relatively small. As described above, since the guide member 55 is retracted by the displacement amount corresponding to the stiffness of the medium P, the load on the medium P from the guide member 55 can be reduced. In addition, the mechanism for displacing the guide member 55 by the load of the spring can be applied to both the rotation type and the slide type.

  Further, the mechanism for displacing the guide member 55 can be realized using a power source such as a solenoid or an electric motor. That is, the guide member 55 is displaced between the guide position and the retracted position by the power of the power source. The mechanism using this power source can be applied to both a rotating system and a sliding system.

  The reason why the protruding end of the holding rib 581 shown in FIG. 3 is offset downward from an imaginary line connecting the nip position of the transport roller pair 33 and the protruding end 57E of the support member 57 is as follows. It is. If the protruding end of the holding rib 581 is located at a position higher than the imaginary line, the trailing end of the preceding medium rises, which hinders the leading end of the succeeding medium from overlapping the trailing end of the preceding medium ( Reason 1). Further, when the protruding end of the pressing rib 581 is located at a position lower than the virtual line, the leading medium is pressed down below the virtual line by the protruding end of the pressing rib 581, so that the leading medium is lower than the pressing position of the preceding medium. The slightly upstream portion is pressed against the protruding end portion 57E of the support member 57, and as a result, the portion of the preceding medium located on the upstream side of the protruding end portion 57E rises. Also in this case, there is a problem in overlapping the leading end of the succeeding medium with the trailing end of the preceding medium (reason 2).

  Further, when the protruding end of the holding rib 581 is at a position lower than the imaginary line, the front end of the medium P pressed downward by the protruding end of the holding rib 581 makes the powder of alumina or the like in the transport roller pair 33. One of the transport drive rollers 33A, which has been subjected to the anti-slipping process by coating or the like, strikes against the transport drive roller 33A. As a result, the skew removing operation cannot be performed as expected (reason 3).

  If the holding rib 581 is designed in an ideal shape so that the protruding end portion is located on the imaginary line, there is a possibility that the above-mentioned inconvenient situation may occur. Therefore, the problem due to the above-described reason 1 is solved by designing the protruding end portion of the holding rib 581 so as to be positioned lower than the imaginary line. The holding rib 581 is urged downward by a spring load, and can be moved upward by the stiffness of the medium P. As a result, the problems caused by the reasons 2 and 3 are also solved.

  The skew correction operation for correcting the skew of the medium P is performed by sequentially changing the state of the medium P from state 1 to state 5 described below. First, the medium P is transported downstream along the ceiling wall portion 56 by the guide member 55 (state 1). Next, the leading end of the medium P is abutted against the stopped transport roller pair 33, and even after the abutment, the intermediate roller 30 applies the transport force downstream to the medium P (state 2). Further, the conveyance force from the intermediate roller 30 is given in a state where a part of the stopped medium P hits the ceiling wall portion 56. Therefore, the downstream portion from the hit position, the medium P is directed downward. It bends (state 3). As the flexure of the medium P grows, the flexure further grows downward while the position contacting the ceiling wall 56 gradually moves upstream (state 4). Then, the skew of the medium P is corrected by causing the edge of the front end of the medium P to follow the pair of transport rollers 33 by the completed bending force (state 5). The medium P whose skew has been corrected is conveyed by the conveying roller pair 33, so that the medium P is printed with the skew corrected.

  Here, a description will be given of a superimposable condition determined by the printing apparatus 12 when the superimposition feeding method is selected. The continuous stacking is permitted when the condition for enabling the stacking is satisfied. The superimposable condition includes a margin condition indicated by a condition in which the trailing edge margin length (bottom margin) of the preceding medium and the leading edge margin length (top margin) of the succeeding medium can be continuously transmitted. As for the margin condition, when both the trailing edge margin length of the preceding medium is in a range of about 30 mm to about 80 mm and the leading edge margin length of the succeeding medium is about 15 mm or more, overlapping continuous feeding is permitted. .

  As for the margin condition, when both of the trailing edge margin length of the preceding medium and the leading edge margin length of the succeeding medium satisfy the following conditions, the overlap continuous feeding is permitted. Here, as shown in FIG. 3, the distance between the nip position of the transport roller pair 33 and the downstream end position of the guide member 55 is LU, the distance between the nip position of the transport roller pair 33 and the most upstream nozzle #Q is Ln, Let Lr be the distance between the most downstream nozzle # 1 and the pressing roller 34C. The first condition is that the trailing edge margin length of the preceding medium falls within the range of “distance Ln + α to distance LU”. Here, the leading end of the succeeding medium overlaps the α portion of the distance Ln + α. The second condition is that the leading edge margin length of the subsequent medium is longer than the distance Lr. By reducing the distance Lr or LU in FIG. 3, the amount of blank space necessary for continuous feeding can be reduced. Note that the distance Ln + α may be simply set to a value 2 · Ln that is twice the distance Ln.

  The reason why the trailing edge margin length of the preceding medium is required to be at least 30 mm is as follows. That is, the distance Ln from the uppermost stream nozzle #Q of the print head 38 to the nip position of the transport roller pair 33 is, for example, about 13 mm, and the nip position of the transport roller pair 33 is defined as an area where the leading end of the subsequent medium overlaps. Approximately 15 mm is required toward the upstream side in the transport direction Y, so that the total is approximately 28 mm. Further, taking into account some manufacturing errors in the length of the medium P in the transport direction Y, the trailing margin length of the preceding medium needs to be at least about 30 mm in total.

  The reason why the trailing edge margin length of the preceding medium is 80 mm or less is as follows. That is, the distance LU from the nip position of the transport roller pair 33 to the downstream end of the guide member 55 in the transport direction Y is about 80 mm. Therefore, if it exceeds 80 mm, the trailing end of the preceding medium reaches the guide member 55, and the leading end of the succeeding medium cannot be overlapped.

  The reason why the leading end margin length of the subsequent medium is required to be about 15 mm is as follows. That is, the distance Lr from the most downstream nozzle # 1 of the print head 38 to the pressing roller 34C is about 14 mm, and needs to be about 15 mm in consideration of some manufacturing tolerance. The reason that the trailing medium requires a leading edge margin length of about 15 mm is as follows. That is, if the leading end of the succeeding medium is not pressed before printing (ink ejection) on the succeeding medium is started, the medium P curls toward the print head 38 at the time of ink ejection, and the medium P Rubbing occurs. Therefore, the leading end of the medium P from the most downstream nozzle # 1 of the print head 38 to the press roller 34C is left blank. Incidentally, the overlapping amount of the preceding medium and the succeeding medium changes according to the trailing margin length of the preceding medium. That is, when the trailing edge margin length of the preceding medium is the minimum of 30 mm, the distance from the most upstream nozzle #Q of the print head 38 to the nip position of the conveying roller pair 33 is reduced by about 13 mm. This is the amount of overlap between the medium and the succeeding medium.

  When the trailing edge margin length of the preceding medium is the maximum of 80 mm, the distance from the most upstream nozzle #Q of the print head 38 to the nip position of the conveying roller pair 33 is reduced by about 13 mm. This is the amount of overlap between the medium and the succeeding medium. As described above, the overlapping amount of the preceding medium and the succeeding medium changes in the range of about 17 mm to about 67 mm according to the trailing margin length of the preceding medium. Note that the above range is merely a simple case and has some problems. A technology that solves the problem is a third embodiment described later.

  As shown in FIGS. 2 and 3, at a position between the transport roller pair 33 and the discharge roller pair 34 in the transport direction Y, a support table 35 capable of supporting the medium P transported along the transport path is provided. Is arranged. The transport roller pair 33 includes a transport drive roller 33A and a transport driven roller 33B that is rotatable following the rotation of the transport drive roller 33A. The discharge roller pair 34 includes a discharge drive roller 34A and a discharge driven roller 34B that can rotate in accordance with the rotation of the discharge drive roller 34A. At a position between the discharge roller pair 34 and the support base 35 in the transport direction Y, a pressing roller 34C that presses the leading end of the medium P before being nipped by the discharge roller pair 34 from above to prevent the medium P from floating. Is provided.

  As shown in FIGS. 2 and 3, the printing unit 25 includes a carriage 36, which is guided by a guide rail unit 37 and is reciprocally movable in the scanning direction X and held at a position above the support base 35. And a print head 38 attached to the surface opposite to the support base 35. The carriage 36 is supported at two places by, for example, a pair of upper and lower guide rails 37, and is guided in a state where it can be moved in the scanning direction X while being positioned in the transport direction Y and the gravity direction Z. A plurality of ink containers 39 of the same number as the ink colors are mounted on the upper portion of the carriage 36. The print head 38 discharges the ink supplied from the ink container 39 mounted on the upper portion of the carriage 36 toward the medium P in the process of moving in the scanning direction X. Therefore, each time the medium P intermittently conveyed during printing stops, printing is performed line by line by the print head 38. The printed medium P is discharged from the discharge port 19 by rotation of the discharge roller pair 34 and the like, and is stacked on the discharge stacker 20. The user stacks the discharge stacker 20 from the storage position shown in FIG. 1 in the transport direction Y to protrude, and then rotates the distal end portion, whereby the discharge stacker 20 is developed into the state of use shown in FIG. The ink container 39 of the present embodiment is configured by an ink cartridge. The ink container 39 is supplied with ink from an ink tank attached to the inside or outside of the main body 15 through an ink tube (neither is shown). May be an adapter that can temporarily store.

  Further, the printing apparatus 12 of the present example has a double-sided printing function. In the main body 15, the reversing passage 40 (in which the medium P conveyed in the conveyance direction Y and printed on one surface (one side) by the printing unit 25 is reversely conveyed in the opposite direction to the conveyance direction Y and guided to the merging unit 263 ( Switchback passage) is provided. The reversing passage 40 extends along a path that passes below the support member 57, and merges with the junction 263 of each of the transport passages 261 and 262. The medium P on which printing on one surface (front surface) has been completed is reversely conveyed along the conveyance path F3 passing through the reversing path 40 and reaches the junction 263. From the junction 263, the intermediate roller 30 and the first driven roller Introduced to the nip with 31. Specifically, when the medium P passes through the reversing passage 40, the flap portion 582 guides the medium P at the time of switchback to the lower side and guides the medium P to the reversing passage 40. When the leading end of the medium P touches the flap portion 582 from the upstream side to the downstream side, the medium P is not regulated because the flap portion 582 rotates toward the downstream side in the transport direction Y. On the other hand, when the medium P is switched back for printing on the other side (back side), the medium P is not rotated even when the leading end of the medium P touches the flap portion 582 from the downstream side to the upstream side, and the medium P is switched back. The medium P is guided to the reverse passage 40.

  Then, the medium P is turned upside down in the process of being conveyed along the outer periphery of the intermediate roller 30, and is passed through the conveying roller pair 33 so that the other surface faces the print head 38 and the printing unit 25. Then, by printing on the other surface (back surface) of the medium P by the printing unit 25, double-sided printing is performed on the medium P. The medium P that has been subjected to double-sided printing is stacked on the discharge stacker 20.

  Further, as shown in FIG. 2, the image reading device 13 is a flat-bed type scanner device, and a document table 132 having a document placing glass plate 134 and a position below the document placing glass plate 134 are moved in the scanning direction X. And a scanner carriage 135 that can reciprocate along. Further, as shown in FIGS. 2 and 3, a power supply unit 59 is provided in the main body 15 at a position higher than the transport path. The power supply unit 59 converts power from, for example, a commercial AC power supply to DC and supplies power necessary for driving to the printing apparatus 12, the image reading apparatus 13, and the automatic document feeder 14.

  As illustrated in FIG. 2, a remaining amount sensor 201 that detects the remaining amount of ink in the ink container 39 is provided at a position downstream of the support base 35 in the transport direction Y in the main body 15. One remaining amount sensor 201 is arranged at a predetermined position in the scanning direction X. In the carriage 36, a plurality of holes 361 to be detected are opened at a position facing the remaining amount sensor 201 in a state of being arranged in a line in the scanning direction X. The ink from each ink container 39 is supplied to the print head 38 via the upper side of the hole 361 for detection. When the hole 361 is located above the remaining amount sensor 201 with the movement of the carriage 36 in the scanning direction X, the remaining amount sensor 201 detects ink from the ink container 39 corresponding to the hole 361 through the hole 361. If there is ink, a non-detection state is set, and if ink runs out, a detection state is set. The plurality of holes 361 need to be arranged in a line along the scanning direction X in order to be detected by the remaining amount sensor 201. The adjustment dial 202 shown in FIG. 3 is provided on the carriage 36, and by operating the adjustment dial 202, the carriage 36 can be rotated around the axis in the direction of gravity Z to adjust the attitude angle thereof. Has become. By adjusting the attitude angle of the carriage 36, all of the plurality of holes 361 can be arranged in a line along the scanning direction X that can be detected by the remaining amount sensor 201. In addition, by operating the adjustment dial 202, the print head 38 can be rotated around the axis in the direction of gravity Z to adjust the attitude angle thereof. By adjusting the attitude angle of the print head 38, the nozzle row 381 (see FIG. 6) is arranged perpendicular to the longitudinal direction of the guide rail portion 37 (that is, the scanning direction X) (that is, parallel to the transport direction Y). It is possible to improve the print quality.

  Next, with reference to FIGS. 4 and 5, details of a configuration for mainly transporting a medium will be described. As shown in FIG. 4, for example, one intermediate roller 30 is disposed at a substantially central position within the width of the conveyance path of the medium P, and as shown in FIGS. The above-mentioned first driven roller 31 and second driven roller 32 are in contact with the portions in this order in the feeding direction. A feeding motor 41 as an example of a first drive source for driving the intermediate roller 30 and the feeding roller 28 (both shown in FIGS. 2 and 3) is provided in the housing 153. The output shaft of the feed motor 41 shown in FIG. 4 is connected to the feed roller 28 and the intermediate roller 30 via a clutch mechanism 42 so that power can be transmitted (see also FIG. 7). In the housing 153, a rotary encoder 43 (hereinafter, also referred to as a "first encoder 43") that detects rotation of the feed motor 41 and outputs a detection signal including a number of pulses proportional to the amount of rotation. ) Is provided.

  As shown in FIGS. 4 and 5, inside the main body 15, a second drive source that drives a transport drive roller 33 </ b> A forming the transport roller pair 33 and a discharge drive roller 34 </ b> A configuring the discharge roller pair 34 is provided. A transport motor 44 is provided as an example. In addition, a rotary encoder 45 (hereinafter, referred to as a “second encoder 45”) that detects the rotation of the rotation shaft of the transport driving roller 33A and outputs a detection signal including a number of pulses proportional to the rotation amount is provided in the housing 153. ) Is provided. At a position between the discharge roller pair 34 and the support base 35 in the transport direction Y, a plurality of pressing rollers 34C are provided in a row in the scanning direction X. In the present embodiment, an example of a transport unit is configured by the transport mechanism 24, the feed motor 41, the transport motor 44, and the like.

  The control unit 50 illustrated in FIG. 4 controls the transport of the medium P by the transport mechanism 24 by controlling the driving of the feed motor 41 and the transport motor 44. The control unit 50 controls the feeding speed of the medium P by controlling the speed of the feeding motor 41 at a target speed corresponding to a count value obtained by counting, for example, the number of pulse edges of the detection signal input from the first encoder 43. I do. The control unit 50 controls the transport speed of the medium P by controlling the transport motor 44 at a target speed corresponding to a count value obtained by counting, for example, the number of pulse edges of the detection signal input from the second encoder 45. I do. In this example, the feed motor 41 and the transport motor 44 are DC motors (DC motors), but at least one of them may be a stepping motor. In this case, since the speed of the motor is controlled based on the number of steps (command value) output by the control unit 50, at least one of the encoders 43 and 45 can be eliminated. In this case, the transport position of the medium P during feeding and transport is obtained from a count value obtained by counting the number of steps used for motor control.

  As shown in FIG. 4, the carriage 36 is fixed to a part of an endless timing belt 47 wound around a pair of pulleys 46, 46 attached to a frame (not shown) in the main body 15. I have. 4 is connected to a drive shaft of a carriage motor 48, and the carriage 36 reciprocates in the scanning direction X via the timing belt 47 when the carriage motor 48 is driven to rotate forward and backward.

  In the housing 153, a linear encoder 49 is extended along the moving path of the carriage 36 so as to extend in the scanning direction X. The linear encoder 49 has a tape-shaped code plate 49A having a large number of light transmission portions (e.g., slits) with a constant pitch, a light-emitting portion provided on the carriage 36, and a light-transmitted portion transmitted through the light transmission portion of the code plate 49A. An optical sensor 49B having a light receiving unit that intermittently receives light. The linear encoder 49 outputs a detection signal including a number of pulses proportional to the moving distance of the carriage 36 in the scanning direction X.

  The control unit 50 shown in FIG. 4 controls driving of the carriage motor 48 to move the carriage 36 in the scanning direction X, and discharges ink droplets to the print head 38 based on the print data PD (see FIG. 7). Print control (ejection control) for printing an image (including a document) based on the print data PD on the medium P is performed. More specifically, the control unit 50 performs speed control and position control of the carriage 36 based on the moving position, moving speed, and moving direction of the carriage 36, which are grasped by detecting the pulse of the detection signal from the linear encoder 49. The print head 38 moves in the scanning direction X together with the carriage 36 in a state where an appropriate gap is provided with respect to the medium P supported by the plurality of ribs 35A protruding from the upper surface of the support table 35, and in the movement process. Ink droplets are ejected toward the medium P.

  The serial printing device 12 performs a printing operation in which the print head 38 moves once in the scanning direction X to print one line on the medium P, and a printing position of the next (next line) in the transport direction Y of the medium P. An image based on the print data PD is printed on the medium P by repeating the transport operation of transporting the print data to the medium P substantially alternately. In this example, one movement in which the print head 38 prints one line on the medium P as the carriage 36 moves in the scanning direction X is also referred to as a “pass”. In the pass from the first time to the final n-th time (where n is a natural number determined according to the print content), printing of one sheet is performed. The medium P being printed is initially nipped only by the transport roller pair 33 as the printing proceeds, is nipped by both the transport roller pair 33 and the discharge roller pair 34 in the next stage, and is discharged by the final stage. Nipped only at 34.

  In FIG. 4, one end (the right end in FIG. 4) on the movement path of the carriage 36 is a home position HP (home position) where the carriage 36 waits during non-printing. A maintenance device 54 for cleaning the print head 38 and the like is disposed at a position corresponding to a position directly below the carriage 36 disposed at the home position HP.

  As shown in FIGS. 4 and 5, at a predetermined position on the transport path between the intermediate roller 30 and the transport roller pair 33 in the transport direction Y, a first sensor 51 capable of detecting the presence or absence of the medium P is provided. The second sensors 52 are arranged in this order at predetermined intervals in the transport direction Y. A third sensor 53 is provided between the first sensor 51 and the second sensor 52 in the direction along the transport path. The control unit 50 uses the detection signals of the sensors 51 to 53 for controlling the transport of the medium P. Note that the control unit 50 of the present embodiment uses the detection signal of the first sensor 51 in the transport control involving the continuous overlapping feed described later.

  As shown in FIG. 5, the first sensor 51 can detect the presence or absence of the medium P at a position near the downstream side in the transport direction Y of the nip between the intermediate roller 30 and the second driven roller 32. The first sensor 51 of the present example is a contact sensor and has a lever 51A that can contact the medium P. When the lever 51A is at the solid line position in FIG. 5, the first sensor 51 does not detect the medium P, but is pressed by the medium P and is located at the detection position indicated by the two-dot chain line in FIG. And outputs a detection signal. The first sensor 51 is turned off, for example, at the time of non-detection, and turned on at the time of detection. Further, the second sensor 52 can detect the presence or absence of the medium P at a position near the upstream side in the transport direction Y of the nip portion of the transport roller pair 33. The second sensor 52 of the present example is a contact-type sensor and has a lever 52A that can contact the medium P. Each of the sensors 51 to 53 may be an optical sensor instead of a contact sensor.

  As shown in FIG. 4, in the present embodiment, a margin is provided at the rear end of the medium P (hereinafter also referred to as “preceding medium P1”) that has been fed earlier, and the medium P is fed next to the preceding medium P1. Overlapping continuous feeding is performed in which the leading medium P1 and the succeeding medium P2 are transported together while maintaining at least a part of the leading end of the medium P (hereinafter, also referred to as “subsequent medium P2”). That is, when the printing operation of the n-th pass (hereinafter also referred to as “last pass”) to the preceding medium P1 is completed, the state where the preceding medium P1 and the succeeding medium P2 are partially overlapped is maintained as shown in FIG. Meanwhile, the succeeding medium P2 is transported (cued-up) to a printing start position (the position shown in FIG. 4). Therefore, compared with the normal feeding method in which the space between the preceding medium P1 and the succeeding medium P2 is spaced and the next medium P2 is caught, the time from the end of printing of the preceding medium P1 to the time of starting printing of the succeeding medium P2 is compared. Waiting time can be reduced. At the time of performing the continuous superimposition, at least before the printing operation of the last pass of the preceding medium P1 is completed, the succeeding medium P2 is moved to the standby position Yw at a transport speed higher than the transport speed of the preceding medium P1 (see FIG. 4). It is necessary to perform an overlapping operation (catch-up feeding operation) for feeding the subsequent medium P2 to a state in which the succeeding medium P2 partially overlaps the preceding medium P1.

  Next, the configuration and control of the feeding mechanism 26 for performing the stacking operation and the stacking continuous feeding will be described with reference to FIG. As shown in FIG. 5, the intermediate roller 30 has a large diameter on one side, which is carried in from the transport roller pair 33 through the reversing passage 40, to reverse the printed medium P with a relatively large radius of curvature. . For this reason, the second nip, which is the nip point of the transport roller pair 33, is located at the first nip position NP1, which is the nip point between the large-diameter intermediate roller 30 and the second driven roller 32 that comes into contact at a position closer to the upper side. The position NP2 is located below the gravity direction Z.

  As shown in FIG. 5, a guide member 55 for guiding the medium P is disposed at a position slightly downstream from the nip portion (first nip position NP1) between the intermediate roller 30 and the second driven roller 32. I have. The guide member 55 is configured such that the feeding path (ejection path) of the medium P sent from the first nip position NP1 is higher than the tangential direction of the intermediate roller 30 and the second driven roller 32 at the nip position NP1 (gravity direction Z). The medium P is guided so as to direct the position (opposite side) to the feeding direction. In this example, the guide member 55 is arranged in a posture in which its guide surface (upper surface) is horizontal, and its sending-out guide direction is horizontal as an example.

  As shown in FIG. 5, on the upper side along the transport path from the first nip position NP <b> 1 of the intermediate roller 30 to the second nip position NP <b> 2 of the transport roller pair 33, the slope becomes lower toward the downstream side in the transport direction Y. A ceiling wall 56 having a guide surface 56A is disposed. The guide direction (for example, the horizontal direction) of the guide member 55 intersects the guide surface 56A. The medium P sent from the guide member 55 at a predetermined feeding speed in the guide direction is conveyed toward the conveying roller pair 33 along a path that keeps the upper limit position as much as possible along the guide surface 56A. At a position slightly upstream of the nip position NP2 of the transport roller pair 33 in the transport direction Y, a standby position Yw serving as a target position of the succeeding medium P2 during the overlapping operation is set. Since the succeeding medium P2 is fed along the guide surface 56A, the leading end of the succeeding medium P2 that has reached the standby position Yw during the overlapping operation is easily stacked on the rear end of the preceding medium P1 from above. .

  A guide surface 57A that supports the rear end of the medium P that has fallen from the guide member 55 after coming off the first nip position NP1 is provided below the ceiling wall 56 shown in FIG. The supporting member 57 which has it is arrange | positioned. The guide surface 57A has a curved surface portion concavely curved so as to become lower toward the downstream side at an upstream portion corresponding to a portion below the downstream end of the guide member 55, and a flat surface portion extending substantially horizontally at the downstream side portion. I have. The trailing end of the succeeding medium P2 after dropping from the guide member 55 is located at a position relatively lower than the first nip position NP1 along a substantially horizontal conveyance path to the nip position NP2 of the conveyance roller pair 33 along the guide surface 57A. Guided through. For this reason, the leading end of the succeeding medium P2 guided along the guide surface 56A in the overlapping operation is easily overlapped above the rear end of the preceding medium P1.

  A clutch mechanism 42 is interposed on a power transmission path between the feed motor 41 and each of the rollers 28 and 30 shown in FIG. The feed motor 41 is a motor that can be driven forward and reverse. The feed motor 41 drives the feed roller 28 and the intermediate roller 30 via the clutch mechanism 42. When the feed motor 41 is driven in the forward direction (CW direction) (forward drive), the clutch mechanism 42 is switched to the first switching position, and the feed roller 28 and the intermediate roller 30 move the medium P to the transport path. Along the normal rotation direction (the direction of the arrow in FIG. 5) that can be conveyed to the printing unit 25 side. On the other hand, when the feed motor 41 is driven in the reverse direction (CCW direction), the clutch mechanism 42 is switched to the second switching position, the feed roller 28 does not rotate, and only the intermediate roller 30 rotates in the forward direction. I do. Further, the clutch mechanism 42 of the present embodiment has a predetermined speed difference between the first rotation speed (first peripheral speed) of the feed roller 28 and the second rotation speed (second peripheral speed) of the intermediate roller 30. Built-in speed reduction mechanism that produces For this reason, the second peripheral speed of the intermediate roller 30 is higher than the first peripheral speed of the feed roller 28.

  Next, the print head 38 will be described with reference to FIG. As shown in FIG. 6, one or more nozzle rows 381 of the same number as the types of ink colors are provided on the nozzle opening surface 38A, which is the bottom surface of the print head 38. In the example of FIG. 6, four nozzle arrays 381 capable of ejecting four color inks of black (K), cyan (C), magenta (M), and yellow (Y) are provided. The nozzle row 381 has a total of Q (for example, 360) indicated by # 1, # 2, ..., #Q (where Q is a natural number of 2 or more) arranged in a line at a constant nozzle pitch in the transport direction Y. It comprises a nozzle 382. Of the nozzles 382 constituting the nozzle row 381, the nozzle 382 of # 1 located at the most downstream in the transport direction Y is referred to as "the most downstream nozzle # 1", and the nozzle 382 of #Q located at the most upstream is "the most upstream nozzle". Also referred to as "Q". Further, as shown in FIG. 6, the length in the transport direction Y of the range where the nozzle 382 from the most downstream nozzle # 1 to the most upstream nozzle #Q is located is referred to as "nozzle row length NL". The ink colors are not limited to four colors, but may be one black color, three colors, or five or more colors. The arrangement pattern of the nozzles 382 constituting the nozzle row 381 is not limited to one row, but may be a zigzag arrangement in which two rows of nozzles are shifted by half a pitch in the row direction. If the number of nozzles per row is plural, the number may be changed as appropriate.

  In the print head 38, a driving element 383 driven when ejecting ink droplets from the nozzle 382 is built in a position corresponding to the nozzle 382. A plurality (Q) of ejection units 384 each including a nozzle 382 and a drive element 383 are provided for each nozzle row. In FIG. 6, the driving element 383 is schematically illustrated outside the print head 38.

  Next, an electrical configuration of the printing apparatus 12 will be described with reference to FIG. As shown in FIG. 7, the control unit 50 of the printing device 12 receives print data PD (print job data) from the host device 100 via the interface 61, for example.

  The multifunction peripheral 11 is communicably connected to, for example, the host device 100 when used. The host device 100 includes a main body 101, an input device 102 including a keyboard 102A and a mouse 102B, and a monitor 103. The main body 101 has a built-in printer driver 104 made of software. The printer driver 104 performs known image processing including resolution conversion processing, color conversion processing, halftone processing, and the like on image data to be printed based on printing conditions, to generate print image data. Then, the printer driver 104 transmits the print data PD generated by attaching the print control command to the print image data as a header to the printing apparatus 12. At this time, if the printing device 12 is a model having a relatively small storage capacity that cannot store one sheet of print data, the printer driver 104 transmits the print data PD obtained by dividing the print data PD into, for example, one line at a time. I do. When the printing apparatus 12 is a model having a relatively large storage capacity capable of storing one sheet of print data, the printer driver 104 transmits the print data PD only once. The printing device 12 interprets a command in the print data PD received from the host device 100, performs transport control and carriage control in accordance with the instruction of the command, and based on the print image data in the print data PD, print unit 25 (in detail, Printing of an image or the like is performed by controlling the ink ejection of the print head 38).

  The operation panel 16 is electrically connected to the interface 61. Each operation signal at the time of operating the power button 17 or at the time of performing a touch operation on the display unit 18 (see FIG. 1) is input from the operation panel 16 to the control unit 50. Further, the control unit 50 displays a menu screen, various messages, and the like on the display unit 18 of the operation panel 16.

  The control unit 50 shown in FIG. 7 includes a computer 62 (for example, a microcomputer), a head drive circuit 63, and motor drive circuits 64-66 shown by a dashed line in FIG. As an input system, a switch system of the operation panel 16, encoders 43 and 45, a linear encoder 49, a first sensor 51, a second sensor 52, and a third sensor 53 are electrically connected to the computer 62. The display unit 18 of the operation panel 16 and various drive circuits 63 to 66 are electrically connected to the computer 62 as an output system. The computer 62 controls the print head 38 via the head drive circuit 63 and controls the carriage motor 48, the feed motor 41, and the transport motor 44 via each of the motor drive circuits 64-66.

  The computer 62 illustrated in FIG. 7 includes a CPU 71 (Central Processing Unit), an ASIC 72 (Application Specific IC), a ROM 73, a RAM 74, and a nonvolatile memory 75, which are connected to each other via a bus 76. I have.

  The ROM 73 stores various control programs and various data. The RAM 74 temporarily stores the print data PD received by the printing apparatus 12, various data such as calculation results by the CPU 71, and various data processed by the ASIC 72. The non-volatile memory 75 stores various programs PR necessary for print control including a firmware program, various data necessary for print processing, and the like. The program PR includes a transfer control program shown in the flowchart of FIG.

  The computer 62 operates according to the program PR read from the non-volatile memory 75, and controls the printing device 12. In detail, the computer 62 controls the carriage motor 48 based on the detection signal from the linear encoder 49 and controls the print head 38 via the head drive circuit 63, thereby printing while moving the carriage 36 in the scanning direction X. A printing operation for discharging ink droplets from the head 38 and printing one line at a time is controlled. The computer 62 controls the drive of the feed motor 41 based on the detection signal of the first encoder 43 and the drive control of the transport motor 44 based on the detection signal of the second encoder 45, so that the printing start position of the medium P is changed. , A conveyance operation including a conveyance operation of the medium P during printing and a discharge operation of the medium P after printing is performed. In this transport control, an overlapping operation of feeding the succeeding medium P2 partially to the preceding medium P1 to the standby position Yw (see FIG. 4), and maintaining the overlapping state of the preceding medium P1 and the succeeding medium P2 The control of the continuous feeding in which the sheets are conveyed at the same conveying speed is included. Note that at least one of the motors 41 and 44 may be replaced with a stepping motor. In this case, the computer 62 responds by outputting the number of steps as a command value to at least one of the motor drive circuits 65 and 66. Drive and control the motor.

  The computer 62 acquires the print condition information from the print data PD (print job data), and supplies the medium P in the cassettes 21 and 22 to the print start position if the print job is, for example, a print job of plain paper, band printing, and single-sided printing. The overlap feeding method is selected as the feeding method to be fed, and the normal feeding method is selected for a print job having other printing conditions. The above-described method of selecting the feeding method is merely an example. For example, in the case of single-sided printing in the high-speed printing mode, the overlapping feeding method may be selected, and in the case of the high-definition printing mode, the normal feeding method may be selected. . Further, at least when the overlap feeding method is selected and in the high-speed printing mode, bidirectional printing for performing printing at both the forward and backward movements of the printing unit 25 is performed. Unidirectional printing in which printing is performed in only 25 unidirectional directions is performed.

Next, with reference to FIG. 8 to FIG. 14, the content of the transport control in the overlap feeding method will be described. This stack feeding method includes a stacking operation and a stack continuous feeding.
As shown in FIG. 8, when the feeding motor 41 is driven to rotate forward, the top leading medium P1 is sent out of the cassette 21 by the rotation of the feeding roller 28 shown in FIG. Slides on the surface (inner surface) of the inclined separating plate 157 to be separated into one. The separated medium P is conveyed along a path along the outer periphery of the intermediate roller 30 while being nipped at two places between the outer peripheral surface of the rotating intermediate roller 30 and the two driven rollers 31 and 32. The paper is fed toward the transport roller pair 33. Thereafter, the skew of the preceding medium P1 is corrected by performing a skew removing operation in which the leading end of the preceding medium P1 is brought into contact with the pair of transport rollers 33 whose rotation is stopped. When the skew removing operation is completed, the feed motor 41 and the transport motor 44 are driven synchronously, so that the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 are driven at the same transport speed, and the preceding medium P1 Is conveyed to the printing start position (being caught).

  Next, as shown in FIG. 8, after the leading medium P1 is located, the printing operation performed by moving the printing unit 25 by driving the carriage motor 48, and the driving of the feeding motor 41 and the conveying motor 44 are performed. Accordingly, the transport operation for transporting the preceding medium P1 is performed substantially alternately. More specifically, after cueing, during one movement of the carriage 36 in the scanning direction X shown in FIG. 10 (during one pass), ink droplets are ejected from the print head 38 to print one line on the preceding medium P1. Printing is performed by performing the printing operation to be performed and the transport operation to transport the preceding medium P1 to the printing position of the next line substantially alternately. As the printing proceeds, the preceding medium P1 is intermittently conveyed to the downstream side in the conveying direction Y, and when the feeding roller 28 comes into contact with the succeeding medium P2 during the printing, the feeding of the succeeding medium P2 starts. Is done. The subsequent medium P2 sent from the cassette 21 slides on the surface of the separation plate 157, is separated into one sheet, and is sent to the intermediate roller 30. In this feeding process, due to the speed difference between the feeding roller 28 and the intermediate roller 30 due to the speed reduction mechanism in the clutch mechanism 42 (see FIG. 7), the succeeding medium P2 has a lower feeding speed than the feeding speed of the preceding medium P1. Since the sheet is fed, the distance between the preceding medium P2 and the succeeding medium P2 gradually increases as the conveyance of the preceding medium P1 proceeds. Therefore, when the medium P is conveyed by the normal feeding method, an interval necessary for the second sensor 52 to detect the ends of the media P1 and P2 is secured between the media P1 and P2.

  By the way, while the preceding medium P1 being printed is nipped between the intermediate roller 30 and the second driven roller 32, the feeding motor 41 and the transport motor 44 are driven in synchronization with each other, so that the intermediate roller 30 is driven. And the transport roller pair 33 must be rotated synchronously at the same transport speed. When the trailing end of the preceding medium P1 deviates from the first nip position NP1 between the intermediate roller 30 and the second driven roller 32, the intermediate roller 30 can be rotated independently of the transport roller pair 33, The overlapping operation of overlapping the succeeding medium P2 on the rear end of the preceding medium P1 is enabled.

  As shown in FIG. 10, when the trailing end of the preceding medium P1 deviates from the nip between the intermediate roller 30 and the second driven roller 32 (first nip position NP1), the first sensor 51 is turned on as shown in FIG. By switching to OFF, the rear end of the preceding medium P1 is detected. When the first sensor 51 switches from ON to OFF, the driving speed of the feeding motor 41 being driven at that time is switched to a speed higher than the speed during the transport operation. As a result, as shown in FIG. 11, the overlapping operation of the succeeding medium P2 (catch-up feeding operation) is started. In the superposing operation, the succeeding medium P2 is fed at a higher feeding speed than the conveying speed of the preceding medium P1 being printed, and is fed to the standby position Yw (see FIGS. 5 and 12) which is the target position of the superposing operation. Is done. At this time, as shown in FIG. 11, the subsequent medium P2 sent out tangentially from the nip portion (first nip position NP1) between the intermediate roller 30 and the second driven roller 32 by the overlapping operation is moved to the first nip position. Since it is guided in a substantially horizontal direction by the guide member 55 arranged near the downstream side of the NP1, it is conveyed along the guide surface 56A.

  As shown in FIG. 8, immediately after the start of the stacking operation, the first sensor 51 switches from OFF to ON by detecting the leading end of the succeeding medium P2. After being driven by the corresponding drive amount, the drive is stopped. As a result, as shown in FIG. 12, the succeeding medium P2 stops at a position where its leading end has reached the standby position Yw. Thereafter, the succeeding medium P2 that has completed the superimposition operation waits at the standby position Yw until the last pass printing operation for printing the last line on the preceding medium P1 is performed. Then, in the determination of the predetermined time before the start of the last pass printing operation shown in FIG. 8, if the superimposable condition is satisfied, the feed motor 41 is driven to rotate forward during the last pass printing operation, and the skew removal operation is performed. That is, as shown in FIG. 13, the skew removing operation in which the intermediate roller 30 rotates by a predetermined rotation amount by the forward rotation of the feed motor 41 and the leading end of the succeeding medium P2 abuts on the transport roller pair 33 whose rotation is stopped is performed. Then, the skew of the succeeding medium P2 is corrected.

  As shown in FIG. 8, when the printing operation of the last pass is completed, the feed motor 41 and the transport motor 44 are driven in synchronization, and the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 have the same transport speed (peripheral speed). ), The continuous feeding is performed in which the preceding medium P1 and the succeeding medium P2 are conveyed together while maintaining the overlapping state at that time. That is, while the preceding medium P1 and the succeeding medium P2 maintain the overlapping amount LP (see FIG. 13) at that time, the successive medium is transported together at the same transport speed until the succeeding medium P2 reaches the printing start position. Is performed. As a result of the continuous continuous feeding, as shown in FIG. 14, the succeeding medium P2 is moved to the printing start position with the leading end of the succeeding medium P2 overlapping the trailing margin of the preceding medium P1.

  Next, the superimposable condition will be described with reference to FIG. As shown in FIG. 15, the standby position Yw is set at a position upstream of the nip position NP2 of the transport roller pair 33 by a predetermined length in the transport direction Y. The predetermined length is, for example, a value within a range of 1 to 20 mm. The standby position Yw is set to a value at which the leading end of the subsequent medium P2 does not reach the nip position NP2 of the transport roller pair 33 in consideration of the skew (skew) and the transport error of the subsequent medium P2 before skew removal. In order to increase the frequency at which the leading end of the succeeding medium P2 is overlapped with the trailing end of the preceding medium P1 in the overlapping operation, the standby position Yw is more preferably located on the downstream side in the transport direction Y. Note that the standby position Yw can be set to an appropriate position within a range between the second nip position NP2 and an intermediate position between the two nip positions NP1 and NP2.

  In FIG. 15, if the length from the second nip position NP2 to the rear end position Y1 of the preceding medium P1 is shorter than the lower limit LL that determines the minimum necessary overlap amount Lmin required for performing the continuous overlap feed, At the time of continuous feeding, it is not possible to secure an overlap of the minimum overlap amount Lmin between the preceding medium P1 and the succeeding medium P2. Therefore, one of the conditions is that the rear end position Y1 of the preceding medium P1 is equal to or larger than the lower limit LL.

  When the trailing end of the preceding medium P1 is placed on the guide member 55, the leading end of the succeeding medium P2 enters below the trailing end of the preceding medium P1, and the overlapping of the preceding medium P1 and the succeeding medium P2. There is a possibility that the order may be reversed upside down, resulting in improper overlap. Therefore, the upper limit position YU is set to the distance LU from the nip position NP2 to the downstream end position of the guide member 55. For this reason, in this example, the margin condition, which is one of the superimposable conditions, is set such that the rear end position Y1 of the preceding medium P1 is within the superimposable area LA (= LL to LU). Note that a configuration without the guide member 55 is also possible, and if this configuration is also included, the overlappable area LA (= LL to LU) is defined by the first nip position NP1 and the second nip position NP2 in the direction along the transport path. It may be set within the range between.

Assuming that the trailing edge margin length Ybm of the preceding medium P1 and the leading edge margin length Ytm of the succeeding medium P2, the margin conditions are expressed as follows using the distances Ln, LU, and Lr shown in FIG.
Ybm ≧ Ln + Lmin + α (1)
Ybm ≦ LU ... (2)
Ytm ≧ Lr + β (3)
Here, α and β are margins that allow for manufacturing errors, and are, for example, values in the range of 0.1 to 5 mm.

  The superimposable condition includes one of the conditions that the print duty value is equal to or less than the threshold value in addition to the margin condition. Here, the print duty value indicates the ratio (%) of the amount of ink per unit area printed on the medium P. For example, in solid printing (solid printing), the printing duty value is 100%. In this example, the superimposable condition is satisfied only when the print duty value is equal to or less than the threshold value and the amount of ink to be printed is not large.

  As described above, the determination time for determining whether the superimposable condition is satisfied is the last (final pass) printing operation of the printing operations performed when the rear end Y1 of the preceding medium P1 is positioned in the superimposable area LA. The transport position is set at the time. That is, the determination time is set to the start position of the transport operation at which the rear end position Y1 of the preceding medium P1 passes through the lower limit position YL of the overlappable area LA. In particular, the determination timing in this example is set to a timing immediately before the start of the final transport operation. When the superimposable condition is satisfied at the determination time, the controller 50 performs the continuous superimposition after the printing operation of the last line (last pass) of the preceding medium P1 is completed. Note that the overlappable area LA is, for example, within a range between the standby position Yw and the downstream end position of the guide member 55 in the transport direction Y, and in a configuration without the guide member 55, the standby position Yw and the first nip position NP1 Can be set to any area within the range between.

  The computer 62 shown in FIG. 7 determines whether the superimposable condition is satisfied as follows. The computer 62 acquires the trailing margin Ybm (bottom margin) of the preceding medium P1 and the leading margin Ytm (top margin) of the succeeding medium P2 from the printing condition information in the print data PD, and obtains both margin lengths Ybm, Ytm. Judge whether or not the conditions satisfying the condition that the continuous feeding is possible are determined. In the present embodiment, the print data used for controlling the print head 38 of the print data PD is sequentially received for one pass (one line). The print data also includes various line feed and page feed commands including the carry amount. The predetermined storage unit of the RAM 74 stores print data for a plurality of passes (for example, a predetermined value within a range of 2 to 5 passes) out of all the passes for one page. In this case, if margin information for at least the two most recent pages can be acquired based on the header information attached to the first received print data in the print data PD, it is determined in advance whether the superimposable condition is satisfied. However, in the case of a configuration in which the margin length cannot be grasped unless it is the timing at which the print data is received, the timing at which the print data of the last line of the preceding medium P1 and the first line of the succeeding medium P2 are received and the margin lengths Ybm and Ytm can be grasped. Then, the success or failure of the superimposable condition may be determined. In the latter case, basically, the determination of the success or failure of the superimposable condition is performed after the start of the superimposition operation. That is, when the first sensor 51 detects the rear end of the preceding medium P1, the overlapping operation of the succeeding medium P2 is performed without determining whether the superimposable condition is satisfied, and the print data of the last line of the preceding medium P1 and the succeeding medium P2 are determined. When the print data of the first line is received, it is determined whether or not the superimposable condition is satisfied.

  When the above-mentioned superimposable condition is not satisfied, the computer 62 does not perform the superimposition operation and the continuous superimposition unless the superimposition operation has already been performed before this determination. For example, when the preceding medium P1 finishes printing the last pass (last line) before the trailing end of the preceding medium P1 is detected by the first sensor 51, the overlapping operation and the overlapping continuous feeding are not performed because the overlapping possible condition is not satisfied. Not done. In this case, when the trailing end of the preceding medium P1 is detected by the first sensor 51 in the discharging process of the preceding medium P1, the computer 62 starts feeding the succeeding medium P2. The operation and cueing for transporting the succeeding medium P2 to the printing start position are performed.

  For this reason, the computer 62 selects the normal feeding method of feeding the succeeding medium P2 with an interval between the preceding medium P1 and the succeeding medium P2 when the overlapping operation is not performed because the condition for enabling the overlapping is not satisfied. . In the normal feeding method, the computer 62 controls the conveyance of the medium P by grasping the conveyance position of the medium P based on the detection position where the second sensor 52 detects the leading end of the medium P.

  The ASIC 72 illustrated in FIG. 7 controls the ink ejection of the print head 38 via the head drive circuit 63 based on the print data PD, and prints an image based on the print data PD on the medium P. The ASIC 72 includes a first counter 81 and a second counter 82.

  When the first sensor 51 switches from ON to OFF and detects the rear end of the preceding medium P1, the control unit 50 causes the first counter 81 to count the number of pulse edges of the detection signal of the first encoder 43, The rear end position Y1 of the preceding medium P1 is obtained from the count value C1. The rear end position Y1 of the preceding medium P1 is indicated by a distance from the nip position NP2 of the transport roller pair 33 to the upstream side in the transport direction Y. As shown in FIG. 15, when the distance from the first nip position NP1 which is the detection position of the first sensor 51 to the second nip position NP2 is YN, and the count value of the first counter 81 is C1, the second nip position The rear end position Y1 of the preceding medium P1 with reference to NP2 is represented by Y1 = YN-C1. Then, the control unit 50 determines whether or not the acquired rear end position Y1 of the preceding medium P1 satisfies a margin condition of LL ≦ Y1 <LU.

  Further, the control unit 50 causes the second counter 82 to count the number of pulse edges of the detection signal of the first encoder 43 from the time when the first sensor 51 switches from OFF to ON and detects the leading end Y2 of the subsequent medium P2. Then, a leading end position Y2 (= YN−C2) of the succeeding medium P2 is obtained from the counted value C2. The control unit 50 can acquire the overlapping amount LP of the preceding medium P1 and the succeeding medium P2 based on the rear end position Y1 of the preceding medium P1 and the leading end position Y2 of the succeeding medium P2.

  The second sensor 52 is used for detecting the leading end and the trailing end of the medium P during normal feeding in which the leading medium P1 and the succeeding medium P2 are fed with a space therebetween. Since there is no space between the preceding medium P1 and the succeeding medium P2 during the overlap feeding, the second sensor 52 is not used. At the time of normal feeding, when the second sensor 52 detects the leading end of the medium P, the second counter 82 starts counting processing for counting the number of pulse edges of the detection signal of the second encoder 45 from the time of the detection. Based on the transport position of the medium P obtained from the count value of the 2 counter 82, a skew removal operation of the medium P and cueing of transport to the print start position are performed.

Hereinafter, the first to sixth embodiments of the printing apparatus 12 in which the stacking operation and the continuous feeding are performed will be sequentially described.
Here, in the first embodiment, when the preceding medium P1 reaches a determination position at which it is determined whether or not the continuous continuous feeding can be performed after the start of the overlapping operation, the succeeding medium P2 finishes the overlapping operation and stops at the standby position Yw. (Preparation of stacking is completed) is set as a condition for performing the continuous feeding. For this reason, if the preparation for stacking is not completed, it is basically to stop the stacking and feeding, but depending on the conditions, the stacking operation being performed at that time is continued to increase the execution frequency of the stacking and feeding. is there. The first embodiment includes three of the first to third embodiments.

  In the second embodiment, the rear end position Y1 of the preceding medium P1 at the time of printing the last line is preferably set on the upstream side in the transport direction Y by changing the range of the nozzle in the transport direction Y used by the print head 38 for printing. , It is easy to satisfy the possible stacking condition, and the frequency of continuous feeding is increased.

  In the third embodiment, the printing of the succeeding medium P2 after the continuous feeding is performed under a predetermined condition in which the print quality is predicted to deteriorate due to printing on a portion overlapping the rear end of the preceding medium P1. Then, the continuous feeding is stopped to prevent the print quality from lowering. The third embodiment includes two of the first and second embodiments.

  In the fourth embodiment, when the movement of the succeeding medium P2 during the stacking operation is detected, and the movement that may cause the stacking operation to fail is detected, the stacking operation is stopped to stop the stacking operation. This is to avoid a printing failure caused by performing the continuous feeding as it is. The fourth embodiment includes two of the first and second embodiments.

  In the fifth embodiment, the stop position accuracy when stopping the succeeding medium P2 at the standby position Yw in the overlapping operation is improved. That is, even if the second sensor 52 disposed immediately upstream of the standby position Yw cannot detect the leading end of the succeeding medium P2 due to the overlap of the media P1 and P2, the second sensor 52 is disposed upstream of the second sensor 52 and overlapped. This is to improve the stop position accuracy by using the first sensor 51 used to determine the start timing of the operation. The fifth embodiment includes two of the first and second embodiments.

  In the sixth embodiment, at least one of the guide member and the support member is made to be movable, and the success rate of continuous continuous feeding is increased. Note that the success of the continuous superimposition includes the success of a series of operations from the superimposition operation to the continuous superimposition, including the success of the skew removal operation. The sixth embodiment includes five items 1 to 5 of the sixth embodiment.

Hereinafter, the first to sixth embodiments will be sequentially described.
<First embodiment>
First, a first embodiment will be described with reference to the drawings. In the first embodiment, the intermediate roller 30 corresponds to an example of a first roller, and the first driven roller 31 and the second driven roller 32 correspond to an example of a plurality of driven rollers. Further, the transport roller pair 33 corresponds to an example of a second roller. Hereinafter, 1 to 3 of the first embodiment will be sequentially described.

(1 of the first embodiment)
At the time of the predetermined determination after the start of the superposition operation and before the printing of the last line of the preceding medium, it is determined whether or not the leading end of the succeeding medium has reached the standby position Yw. If the succeeding medium has reached the standby position Yw, overlapping continuous feeding is performed after the printing operation of the last line is completed. However, if the subsequent medium has not reached the standby position Yw, overlapping continuous feeding is not performed.

  As shown in FIG. 16, the standby position Yw is set at a position upstream of the nip position NP2 of the transport roller pair 33 by a predetermined length L in the transport direction Y. The standby position Yw is obtained by adding a slight margin to a value at which the leading end of the succeeding medium P2 does not reach the nip position NP2 of the conveying roller pair 33 in consideration of the inclination due to the skew of the subsequent medium P2 and the transport error before the skew removing operation. Is set to a value. The length L is set to, for example, a value within a range of 2 to 10 mm. The standby position Yw is more preferably a position on the downstream side in the transport direction Y, in order to secure a little more overlapping amount at the time of continuous feeding. However, if the standby position Yw is too close to the second nip position NP2, the leading end of the succeeding medium P2 after the overlapping operation may hit the transport roller pair 33, and may be transported by the transport roller pair 33 during rotation. Therefore, the standby position Yw is set to the above position. Note that the standby position Yw may be set to an appropriate position within a range between the second nip position NP2 and an intermediate position between the two nip positions NP1 and NP2 in the transport direction Y.

  The control unit 50 of the present embodiment completes the superimposition operation when the superimposition operation is started, and the control unit 50 is located at the determination position located on the upstream side in the conveyance direction Y from the conveyance position where the printing of the last line of the preceding medium P1 is performed. It is determined whether or not. The completion of the stacking operation at this determination position is a condition for permitting the execution of the continuous stacking. In particular, in the present embodiment, as shown in FIG. 16, the transport position (medium stop) of the last path among the paths in the section (LL ≦ Y1 ≦ LU) where the rear end position Y1 of the preceding medium P1 is located in the overlappable area LA. Position) is set as the determination position of the preceding medium P1. When the preceding medium P1 is at the determination position, the succeeding medium P2 has completed the overlapping operation and is stopped at the standby position Yw, which is a condition for permitting the execution of the continuous continuous feeding. Hereinafter, this condition is referred to as a “first overlap continuous transfer execution condition”.

  As described above, the determination timing for determining whether or not the first superimposed continuous feeding execution condition is satisfied is determined by the last one of the passes in one or more printing operations performed when the rear end Y1 of the preceding medium P1 is positioned within the superimposable area LA. The transport position (determination position) at which the pass printing operation is performed is set. That is, at the determination time, the transport operation (hereinafter, also referred to as “final transport operation”) in which the trailing end position Y1 passes the lower limit position YL of the overlappable area LA due to the transport of the preceding medium P1. Set to position. In particular, the determination timing in this example is set to a timing immediately before the start of the final transport operation. This is because the minimum overlapping amount may not be ensured even if the leading end of the succeeding medium P2 reaches the standby position Yw after the trailing end Y1 of the preceding medium P1 passes through the overlappable area LA. Therefore, the timing is set slightly earlier than when the trailing end Y1 of the preceding medium P1 exits the overlappable area LA, that is, immediately before the start of the final transport operation when the trailing end Y1 exits. Also, the reason why the determination timing is set to the timing immediately before the start of the final transport operation in the period at the start position of the final transport operation is that the determination timing is set as late as possible to satisfy the first overlapping continuous transfer execution condition. This is because the frequency of establishment increases. When the first overlap continuous transfer execution condition is satisfied at the determination time, the control unit 50 performs the overlap continuous transfer after the end of the printing operation of the last line (last pass) of the preceding medium P1. Note that the overlappable area LA is, for example, within a range between the standby position Yw and the downstream end position of the guide member 55 in the transport direction Y, and in a configuration without the guide member 55, the standby position Yw and the first nip position NP1 Can be set to any range within the range between.

  Further, in the present embodiment, even if the first overlapping continuous feeding execution condition is not satisfied at the determination time, the overlapping continuous feeding is performed within the range of the predetermined condition, and the overlapping continuous feeding is not performed outside the range of the predetermined condition. Even if the first overlapping continuous feeding execution condition is not satisfied, the reason why the overlapping continuous feeding is performed within the range of the predetermined condition is that the overlapping continuous feeding may be substantially possible. Particularly, in the present embodiment, since the distance that the succeeding medium P2 must catch up with the preceding medium P1 in the overlapping operation is relatively long, even if the conditions for performing the continuous continuous feeding are substantially satisfied, the overlapping operation is rarely performed at the time of determination. There is. Therefore, even if the first overlapping continuous feeding execution condition is not satisfied, the overlapping operation is continued within the range of the predetermined condition, and the overlapping continuous feeding is performed after the completion. In this example, the following predetermined position condition is adopted as the predetermined condition. The predetermined position condition is a condition that defines the positional relationship between the rear end position Y1 of the preceding medium P1 and the front end position Y2 of the succeeding medium P2 during the overlapping operation at the time of determination. Even if the stacking operation is being performed at the time of the determination, if the predetermined position condition is satisfied, the stacking continuous feeding can be performed while securing the minimum stacking amount. In the present embodiment, in addition to the first overlap continuous transfer execution condition, a second overlap continuous transfer execution condition that permits execution of the overlap continuous transfer even if the first overlap continuous transfer execution condition is not satisfied at the time of determination is prepared. I have. If one of the first overlapped continuous transfer execution condition and the second overlapped continuous transfer execution condition is satisfied, the execution of the overlapped continuous transfer is permitted. In addition, when the second overlapping continuous transmission item condition is satisfied, the same determination as the first overlapping continuous transmission execution condition is performed at the time of the next and subsequent determinations (for example, the timing immediately before the start of the transport operation after the final transport operation). When it is confirmed that the succeeding medium P2 is stopped at the standby position Yw, the continuous feeding is performed after the printing operation of the last line.

  Next, with reference to FIG. 17, a description will be given of the second overlap continuous feeding execution condition. FIG. 17 shows a state in which the succeeding medium P2 is in the middle of the stacking operation at the time of determining the first stacking continuous transfer execution condition. In the second overlapping continuous feeding execution condition determined when the overlapping operation is being performed at the time of the determination, the positional relationship between the rear end position Y1 of the preceding medium P1 and the front end position Y2 of the succeeding medium P2 satisfies the following predetermined position condition. That is. The predetermined position condition is that the rear end position Y1 of the preceding medium P1 is located upstream of the lower limit position YL of the overlappable area LA (= LL to LU) in the transport direction Y, and the preceding medium P1 and the succeeding medium P2 Are not separated beyond a predetermined distance in the direction along the transport path. Here, the phrase “not separated beyond the predetermined distance” means that the rear end of the preceding medium P1 overlaps the front end of the succeeding medium P2, and that the rear end of the preceding medium P1 and the front end of the succeeding medium P2 overlap. And a state where the rear end of the preceding medium P1 and the front end of the succeeding medium P2 are separated within a predetermined distance. Here, the predetermined distance is a value that can ensure a necessary overlap with the preceding medium P1 by a minimum amount or more when the overlapping operation of the succeeding medium P2 is continued and stopped at the standby position Yw. The predetermined distance depends on the standby position Yw, the lower limit position YL (minimum overlapping amount), the catch-up feeding speed profile, the conveying speed profile of the preceding medium P1, the rear end position Y1, and the front end position Y2. The predetermined distance may be a variable value or a fixed value (minimum predetermined distance).

  In FIG. 17, when the length from the second nip position NP2 to the rear end position Y1 is shorter than the minimum overlap amount, the minimum length when the leading end of the succeeding medium P2 that has continued the overlap operation reaches the standby position Yw. The overlapping of the overlapping amount cannot be secured. Therefore, in the present example, as the predetermined position condition, the rear end position Y1 of the preceding medium P1 is within the overlappable area LA (= LL to LU), and the rear end of the preceding medium P1 and the front end of the succeeding medium P2. Are set so that there is an overlap of more than a predetermined amount (ymm). In other words, the predetermined position condition is that when the rear end position Y1 of the preceding medium P1 is located within the overlappable area LA (= LL to LU) (LL ≦ Y1 ≦ LU), then the front end of the subsequent medium P2 The condition is that the position Y2 has passed the set position YS of the distance y (mm) from the rear end position Y1 of the preceding medium P1 to the downstream side in the transport direction Y. In this case, the predetermined amount (ymm) may be any value larger than 0 (zero).

  The control unit 50 acquires the trailing end position Y1 of the preceding medium P1 and the leading end position Y2 of the succeeding medium P2, and executes the second overlap continuous transfer of LL ≦ Y1 ≦ LU and Y1-Y2 ≧ y (where y> 0). If the condition is satisfied, the overlapping operation of the succeeding medium P2 is continued, and if the second overlapping continuous feeding execution condition is not satisfied, the overlapping operation is not continued. If the superposing operation can be continued and completed, the control unit 50 performs continuous superimposing after the printing operation of the last line on the preceding medium P1 is completed. On the other hand, if the second superimposed continuous transfer execution condition is not satisfied, the controller 50 does not perform the superimposed continuous feeding after stopping the superimposing operation, performs an interval creating operation for forming an interval between the media P1 and P2, and Normal feeding is performed in which the medium P2 is caught to the printing start position at an interval between the medium P2 and the preceding medium P1.

  In the present example, the overlappable area LA is common to the first overlap continuous transfer execution condition and the second overlap continuous transfer execution condition. Is also good. Further, the condition of LL ≦ Y1 may be eliminated from the above-described second overlap continuous transmission execution condition. In this case, if the minimum overlapping amount is not secured at the time of the final determination after the completion of the continuous overlapping operation, the execution of the continuous overlapping feeding may be stopped.

  Next, the operation of the printing device 12 will be described. Hereinafter, with reference to FIG. 8 and FIGS. 18 to 20, a description will be given of the transport control including the overlapping continuous feeding performed by the computer 62 in the control unit 50 executing the program PR shown in the flowchart of FIG. 20. In FIGS. 8, 18 and 19, the feed motor 41 distinguishes between forward rotation (CW) and reverse rotation (CCW) to indicate the driving speed, and the carriage motor 48 does not distinguish between forward rotation and reverse rotation. This shows the motor drive speed. Further, the transport motor 44 only drives forward.

  In step S11, printing of the preceding medium is started. That is, as shown in FIG. 8, the feed motor 41 is driven in the normal rotation direction (CW direction), and the preceding medium P1 is fed via the intermediate roller 30 by the rotation of the feed roller 28 and the intermediate roller 30. Thereafter, the sheet is transported from the first nip position NP1 to the second nip position NP2. The skew of the preceding medium P1 is corrected by the skew removing operation being performed by abutting the leading end of the leading end against the transport roller pair 33 during the rotation stop. Next, the normal rotation drive of the feed motor 41 and the drive of the transport motor 44 are performed in synchronization, and the preceding medium P1 reaches the print start position by rotating the intermediate roller 30 and the transport roller pair 33 at the same transport speed. It is caught. Then, while the carriage motor 48 is driven and the carriage 36 moves in the scanning direction X, the print head 38 ejects ink droplets to print one line (one pass) on the preceding medium P1. Thereafter, the transport operation of transporting the preceding medium P1 to the printing position of the next line and the one-pass printing operation of printing one line are performed substantially alternately, and the printing on the preceding medium P1 is advanced.

  In step S12, it is determined whether the first sensor has been switched from ON to OFF. That is, it is determined whether or not the rear end of the preceding medium P1 has passed the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 switches from ON to OFF, the process proceeds to step S13. If the first sensor 51 does not switch from ON to OFF, the process waits until the first sensor 51 switches. Printing on the preceding medium P1 is also performed during this waiting period. The computer 62 obtains the rear end position Y1 of the preceding medium P1 from the counted value by causing the first counter 81 reset when the first sensor 51 switches from ON to OFF to perform the counting process. I do.

  In step S13, it is determined whether the superimposable condition is satisfied. If the superimposable condition is satisfied, the process proceeds to step S14, and if the superimposable condition is not satisfied, the routine ends. When the routine ends, normal feeding is performed in which feeding is performed with an interval between the media P1 and P2.

  In step S14, an overlapping operation for feeding the succeeding medium to the standby position is started. More specifically, when the first sensor 51 is switched from ON to OFF (a positive determination is made in S12), the computer 62 drives the feed motor 41 to rotate forward, and the rotation of the feed roller 28 and the intermediate roller 30 causes the subsequent medium to rotate. P2 is fed toward the standby position Yw. In this feeding process, the computer 62 causes the second counter 82, which has been reset when the first sensor 51 detects the leading end of the succeeding medium P2, to perform a counting process. Get Y2. Then, the reverse drive of the feed motor 41 is continued until the leading end position Y2 of the succeeding medium P2 reaches the standby position Yw.

  In step S15, it is determined whether or not the last pass when the trailing end of the preceding medium is within the superimposable area (also referred to as “superimposable final pass”). That is, it is determined whether or not it is the determination time set to the timing immediately before the start of the next transport operation after the printing operation of the last pass capable of overlapping is completed. If it is the determination time that the preceding medium P1 is at the transport position of the last stackable path, the process proceeds to step S16. If not, the process waits until the determination time comes. Note that the printing of the preceding medium P1 is continued during the waiting period.

  In step S16, it is determined whether or not the overlapping operation has been completed. That is, it is determined whether or not the first overlap continuous feeding execution condition is satisfied. In this example, the computer 62 determines whether or not the succeeding medium P2 is stopped at the standby position Yw, that is, whether or not the preparation for performing the continuous feeding is completed and the preparation is completed. For example, as shown in FIG. 16, if the succeeding medium P2 is stopped at the standby position Yw and the stacking operation has been completed, the process proceeds to step S22. Also, as shown in FIG. 17, if the succeeding medium P2 has not stopped at the standby position Yw and is in the middle of the overlapping operation, the process proceeds to step S17.

  In step S22 shown in FIG. 20, a skew removing operation is performed during the last pass. That is, when the computer 62 completes the transport operation of transporting the preceding medium P1 to the position of the last pass and stops driving the transport motor 44, the computer 62 drives the feed motor 41 in the reverse direction to transport the subsequent medium P2 from the standby position Yw. A skew removing operation is performed in which the leading end is brought into contact with the transport roller pair 33 whose rotation is stopped.

  Then, in the next step S23, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the conveying motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are The continuous feeding (hatched portion in FIG. 8) is performed in which the sheets are transported together at the same transport speed while maintaining the overlapping amount. As a result, the succeeding medium P2 is moved to the printing start position while maintaining the overlapping amount with the preceding medium P1. As shown in FIG. 8, when the printing of the last line of the first sheet is completed, the first and second sheets of the media P1 and P2 are conveyed together while maintaining at least a part of the margin amount overlapping. Then, the second medium P2 is located at the print start position. In the case of this overlap feeding method, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the carry amount at the time of cueing for conveying the succeeding medium P2 to the printing start position is determined by the following medium. P2 can be relatively reduced compared to the case of the normal feeding system in which P2 is conveyed with an interval between it and the preceding medium P1. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, in step S17 in FIG. 20, it is determined whether the last pass is being printed. If the last pass is not being printed, that is, if the last pass printing has not been started yet, the process proceeds to step S18. If the last pass is being printed, the process proceeds to step S24.

  In step S18, it is determined whether the rear end of the preceding medium is within the overlappable area and the rear end of the preceding medium and the front end of the succeeding medium overlap by ymm or more. That is, whether or not the positional relationship between the rear end position Y1 of the preceding medium P1 and the front end position Y2 of the succeeding medium P2 satisfies the predetermined position condition is determined by determining whether or not the second superposition continuous execution condition is satisfied. . In other words, the second overlap continuous feeding execution condition is such that the rear end of the preceding medium P1 is within the overlappable area LA and the position of the distance ymm from the rear end position Y1 of the preceding medium P1 to the downstream side in the transport direction Y. The condition is that the leading end of the succeeding medium P2 passes through the set position YS (see FIG. 17). The computer 62 uses the rear end position Y1 obtained from the count value of the first counter 81 and the front end position Y2 obtained from the count value of the second counter 82 to execute the second overlap continuous feeding condition (LL ≦ Y1 < LU and Y1−Y2 ≧ y) are determined. If the second overlap continuous transfer execution condition is not satisfied, the process proceeds to step S24, and if the second overlap continuous transfer execution condition is satisfied, the process proceeds to step S19.

  In step S19, the subsequent medium overlapping operation is continued. The computer 62 continues the overlapping operation of the subsequent medium P2 by continuing the reverse rotation drive of the feed motor 41. For this reason, the succeeding medium P2 during the overlapping operation continuously moves toward the standby position Yw.

  In the next step S20, it is determined whether or not printing of one pass of the preceding medium has been completed. After the final transport operation, the carriage 36 moves in the scanning direction X to print one pass until the last pass printing operation is completed, and a transport operation for transporting the preceding medium P1 to the printing position of the next line. Are repeated substantially alternately. Then, in this step S20, it is determined whether or not it is the timing when the printing operation for one pass of the preceding medium is completed, that is, whether it is the timing immediately before the start of the next transport operation. If printing for one pass of the preceding medium P1 is completed, the process proceeds to step S21. If printing for one pass is not completed, the process returns to step S17.

  In step S21, it is determined whether or not the overlapping operation has been completed. That is, it is determined whether or not the succeeding medium P2 is stopped at the standby position Yw. If the stacking operation has not been completed, the process returns to step S17. If the stacking operation has been completed, the process proceeds to step S22.

  When the process returns to step S17, the processes in steps S17 to S21 are determined to be affirmative in step S17 (during the printing of the last pass) or to be negative in step S18 (unsatisfied with the condition for executing the second overlap continuous feeding). Alternatively, the processing is repeated until an affirmative determination (completion of the overlapping operation) is made in step S21.

  In the period before the start of the printing of the last pass (negative determination in S17), if the superimposition operation is completed (the affirmative determination in S21) while the second superimposed continuous transfer execution condition is satisfied (a positive determination in S18), the process proceeds to step S22. move on. In this case, the skew removal operation is performed during the last pass (S22), and after the printing operation of the last pass is completed, the preceding medium P1 and the succeeding medium P2 are maintained in a partially overlapped state, and the succeeding medium P2 is searched for. Continuous feeding is performed (S23).

  For example, as shown in FIG. 18, when the first sensor 51 switches from ON to OFF, the feed motor 41 is switched from reverse rotation drive to normal rotation drive, and further accelerated at, for example, the highest speed to start the overlapping operation. You. Thereafter, even when it is determined that the succeeding medium P2 has not stopped at the standby position Yw where the superimposition operation has been completed, at the time of the determination immediately before the conveyance operation of the preceding medium P1 is started from the conveyance position of the last pass in the superimposable area LA. If the rear end of the preceding medium P1 is within the overlappable area LA and the second overlap continuous feeding execution condition of the overlap amount ≧ y is satisfied, the overlap operation is continued. Then, if the leading end of the succeeding medium P2 reaches the standby position Yw and the overlapping operation can be completed before the printing of the last pass is started, the overlapping continuous feeding is performed after the skew removing operation. At this time, after the completion of the stacking operation, the feed motor 41 is driven in reverse during the printing operation of the last pass, and the skew of the subsequent medium P2 is performed. When the printing of the last pass is completed, the feed motor 41 and the transport motor 44 are driven synchronously, so that the preceding medium P1 and the succeeding medium P2 are transported together while maintaining the overlapping amount at that time. (See the hatched portion in FIG. 18). As a result of the continuous feeding, the succeeding medium P2 is moved to the printing start position by a relatively short conveyance amount. Therefore, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, in FIG. 20, if the printing of the last pass is being performed before the overlapping operation is completed (YES determination in S17), or if the second continuous feeding execution condition is not satisfied (NO determination in S18), the process proceeds to step S24. move on.

  In step S24, a medium interval creation operation is performed. In the medium interval creating operation, the overlapping operation is first stopped. Due to this suspension, the succeeding medium P2 that was in the middle of the stacking operation stops at a position on the upstream side in the transport direction Y from the standby position Yw. When the printing of the last pass of the preceding medium P1 is completed, the preceding medium P1 is ejected, and after the ejection is completed, the succeeding medium P2 is located at the printing start position. If the rear end position Y1 is at a position that has passed the second nip position NP2 by a predetermined distance or more during the printing operation of the last pass, the skew removing operation of the succeeding medium P2 is performed during the printing operation of the last pass, and After the end of the printing operation, the ejection of the preceding medium P1 and the cueing of the succeeding medium P2 may be performed with an interval therebetween.

  For example, as shown in FIG. 19, when the first sensor 51 switches from ON to OFF, the feed motor 41 is switched from reverse drive to forward drive, and further accelerated to start the overlapping operation. When it is determined that the overlay operation has not been completed at the time immediately before the start of the transport operation for transporting the preceding medium P1 from the transport position of the last pass in the overlayable area LA, for example, the overlap amount <y, and the second If the superimposed continuous transfer execution condition is not satisfied, the superimposition operation is stopped at that time. In this case, after the printing operation of the last pass is completed, an interval creating operation is performed. That is, the computer 62 drives the transport motor 44, and first discharges the preceding medium P1 by rotation of the transport roller pair 33 and the discharge roller pair 34. Thereafter, the computer 62 drives the feeding motor 41 to skew the subsequent medium P2. Then, after the preceding medium P1 has been discharged, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, and locates the succeeding medium P2 to the printing start position. During the ejection of the preceding medium P1, the computer 62 starts the reverse rotation drive of the feed motor 41 at a timing when the rear end of the preceding medium P1 passes the transport roller pair 33 and a certain interval is secured, and the skew is removed. The conveyance of the completed succeeding medium P2 to the printing start position may be started.

  Also, for example, as shown in FIG. 18, even when the overlapping operation of the succeeding medium P2 is continued, the printing of the last pass is started before the completion of the continued overlapping operation, or the second overlapping continuous feeding execution condition is not satisfied. Then, the overlapping operation is stopped at that time. In these cases, when the printing of the last pass is completed thereafter, the ejection of the preceding medium P1 and the cueing of the succeeding medium P2 are performed with an interval between the media P1 and P2 by performing the medium interval creating operation (S24). .

  In step S21, when the last pass is being printed during the deceleration after the succeeding medium P2 has reached the standby position Yw during the continuation of the stacking operation, the transport roller that has stopped rotating the leading end of the succeeding medium P2 as it is. By striking the pair 33, the overlapping operation and the skew removing operation may be performed together.

  As described above, according to the overlap feeding method of the present embodiment, after the printing of the preceding medium is completed, the overlapping section that conveys the rear end of the preceding medium P1 and the leading end of the succeeding medium P2 together in a partially overlapped state. The frequency of sending is increased. That is, at the time of the determination immediately before the start of the transport operation from the position of the last pass in the overlappable area LA, even if the succeeding medium P2 is being overlapped, the trailing end position Y1 of the preceding medium P1 and the leading end position of the succeeding medium P2 If the positional relationship with Y2 satisfies a predetermined position condition (second overlapping continuous feeding execution condition), the overlapping operation is continued. Then, the frequency at which the overlapping operation can be completed by completing the overlapping operation by the last pass increases. As a result, the printing throughput is improved.

According to 1 of the first embodiment described in detail above, the following effects can be obtained.
(1-1) The control unit 50 determines that the positional relationship between the leading end position Y2 of the succeeding medium P2 during the overlapping operation and the trailing end position Y1 of the preceding medium P1 satisfies a predetermined position condition (second overlapping continuous transfer execution condition). If so, after the completion of the superposition operation, the continuous superimposition feeding is performed in which the preceding medium P1 and the subsequent medium P2 are conveyed together until the subsequent medium P2 reaches the printing start position while maintaining the overlapping state. On the other hand, if the predetermined position condition is not satisfied, the succeeding medium P2 is conveyed to the printing start position at an interval from the preceding medium P1. Therefore, when the rear end of the preceding medium P1 is located on the upstream side of the lower limit position YL in the transport direction Y, even if the succeeding medium P2 has not reached the standby position Yw, the overlapping continuous feeding is performed. In some cases, this increases the frequency of performing the continuous feeding. As a result, the printing throughput is further improved.

  (1-2) The control unit 50 controls the rear end of the succeeding medium P2 during the superimposing operation and the rear end of the preceding medium P1 when the rear end is located upstream of the lower limit position YL in the transport direction Y. Has an overlap of a predetermined amount (ymm) or more, the preceding medium P1 and the succeeding medium P2 are overlapped and fed. On the other hand, if the overlap does not exceed the predetermined amount, the succeeding medium P2 is conveyed to the printing start position with an interval from the preceding medium P1. Therefore, when the trailing end of the preceding medium P1 is at the transport position of the last pass among the paths when the trailing end is located on the upstream side of the lower limit position YL in the transport direction Y, the succeeding medium P2 has not reached the standby position Yw. However, the continuous feeding may be performed in some cases, and the frequency of the continuous feeding can be increased. As a result, the printing throughput is further improved.

  (1-3) The control unit 50 determines whether or not the superposition operation has been completed when the preceding medium P1 is located at the start position of the transport operation in which the rear end of the preceding medium P1 passes the lower limit position YL. . If the stacking operation has been completed, the continuous stacking is performed. On the other hand, if the overlapping operation has not been completed, it is determined whether or not the leading end of the succeeding medium P2 and the trailing end of the preceding medium P1 during the overlapping operation overlap by a predetermined amount or more. Therefore, even when the succeeding medium P2 has not reached the standby position Yw at the time of the determination, the overlapped continuous feeding may be performed, and the frequency of the repeated continuous feeding can be increased.

  (1-4) The lower limit position YL is the preceding medium when the leading end of the succeeding medium P2 reaching the standby position Yw and the trailing end of the preceding medium P1 have the minimum overlapping amount necessary for performing continuous continuous feeding. Is set at the rear end position. When the rear end of the preceding medium P1 is located upstream of the lower limit position YL in the transport direction Y, the control unit 50 determines whether or not the overlap has a predetermined amount (ymm) or more. In this determination, if the minimum overlap amount cannot be obtained, the predetermined position condition is not satisfied, so that it is possible to more appropriately determine whether or not to perform the continuous overlap feed. Then, at the time of this determination, even if the overlapping operation is not completed, the overlapping continuous feeding may be performed, so that the frequency of performing the overlapping continuous feeding can be increased.

  (1-5) The control unit 50 controls the rear end of the preceding medium P1 when the rear end of the preceding medium P1 is located on the upstream side in the transport direction Y from the lower limit position YL, and the subsequent medium P2 during the overlapping operation. If the leading end has an overlap of a predetermined amount (ymm) or more, the overlapping operation of the succeeding medium P2 is continued. On the other hand, if the overlap does not exceed the predetermined amount, the overlapping operation of the succeeding medium P2 is not continued. Accordingly, when the overlapping operation of the succeeding medium P2 is continued, the frequency of performing the continuous continuous feeding can be increased.

  (1-6) The transport mechanism 24 is driven by the intermediate roller 30 driven by the feed motor 41 and the transport motor 44 as an example of the second drive source, and is more transported in the transport path than the intermediate roller 30 in the transport path. And a transport roller pair 33 as an example of a second roller disposed at a position downstream of the transport roller. At the timing when the rear end of the preceding medium P1 has passed through the last nip (first nip position NP1) of the nip portion between the intermediate roller 30 and the plurality of driven rollers 31, 32, the transport speed of the succeeding medium P2 to the preceding medium P1 A superimposition operation for transporting at a higher transport speed until reaching the standby position Yw is started. Then, if the subsequent medium P2 has completed the overlapping operation by the time the transport operation to the printing position of the last line of the preceding medium P1 is started, the overlapping continuous feeding is performed. When the rear end of the preceding medium P1 passes through the final nip position (first nip position NP1) among a plurality of nip positions between the intermediate roller 30 having a relatively large diameter and the plurality of driven rollers 31, 32, as described above. The overlapping operation of the succeeding medium P2 is started from a position having a relatively long interval. Therefore, even if the interval between the preceding medium P1 and the succeeding medium P2 at the start of the overlapping operation is relatively long, and the frequency of the succeeding medium P2 being in the middle of the overlapping operation at the time of determination is relatively high, the frequency of performing the continuous continuous feeding is increased. be able to.

  (1-7) When the rear end of the preceding medium P1 exceeds the lower limit position YL in the next transport operation, the control unit 50 terminates the current transport operation immediately before the next transport operation and performs the next transport. At the time of the determination before the start of the operation, when the succeeding medium P2 is in the middle of the overlapping operation, if there is an overlapping amount equal to or more than a predetermined amount (ymm) between the trailing end of the preceding medium P1 and the leading end of the succeeding medium P2, Overlapping continuous feeding is performed. Therefore, it is possible to increase the frequency of performing the continuous feeding.

  (1-8) After starting the superimposition operation of the succeeding medium P2, the control unit 50 determines that the superimposition operation has been completed when the preceding medium P1 is at the determination position. Perform continuous feeding. On the other hand, if the overlapping operation is not completed, the control unit 50 continues the overlapping operation within a range that satisfies the second overlapping continuous transfer execution condition as an example of the predetermined condition. After the printing operation of the line is completed, the overlapping continuous feeding is performed. If the second overlapping continuous feeding execution condition is not satisfied, the overlapping continuous feeding is not performed. Therefore, in the determination when the preceding medium P1 is at the determination position (immediately before the start of the final transport operation), even if the succeeding medium P2 has not completed the overlapping operation, the overlapping continuous feeding may be performed. This makes it possible to increase the frequency of the continuous feeding and improve the printing throughput.

  (1-9) When the second overlapping continuous feeding execution condition is not satisfied, the control unit 50 conveys the succeeding medium P2 to the printing start position with an interval between the preceding medium P1 and the succeeding medium P2. Therefore, it is possible to avoid the occurrence of a jam or the like due to continuous feeding in a state where the amount of overlap between the trailing end of the preceding medium P1 and the leading end of the succeeding medium P2 is insufficient.

(2 of the first embodiment)
Next, 2 of the first embodiment will be described with reference to FIGS. In the present embodiment, as in the case of the first embodiment, even when the superimposition operation is not completed at the time of the determination when the preceding medium P1 is at the determination position (for example, immediately before the start of the final transport operation), a predetermined The overlapping operation is continued within a range satisfying the condition. The predetermined condition in the present embodiment is a condition that the overlapping operation can be completed at least within a predetermined time. In particular, in this example, the start time of the next transport operation is delayed by waiting for the preceding medium P1, and the time for continuing the overlapping operation is secured. The predetermined condition is that the waiting time for the preceding medium P1 falls within the predetermined time. By delaying the start time of the next transport operation started after the determination time, the final determination time for determining whether or not to perform the continuous feeding can be postponed, and the overlapping operation can be continued until then. The overlapping operation of the succeeding medium P2 is continued for a predetermined time. If the overlapping operation can be completed within the predetermined time, the overlapping operation is performed after the printing operation of the last line is completed. If the overlapping operation cannot be completed within the predetermined time, the overlapping operation is not performed. For this reason, in the present embodiment, the preceding medium P1 is put on standby when at least the overlapping operation can be completed within a predetermined time. However, when the overlapping operation cannot be completed within the predetermined time, the preceding medium P1 is put on standby. In this example, the standby time Tmax is set as an example of the predetermined time.

  More specifically, as shown in FIG. 21, even when the overlapping operation is being performed at the time of determining the last pass in the overlappable area LA (the first determination on the left side in FIG. 21), the preceding medium P1 is limited to the standby time Tmax. And the start timing of the next transport operation is delayed. If the stacking operation can be completed within the standby time Tmax, the next transport operation of the preceding medium P1 (two-dot chain line in FIG. 21) is started at that time, and if the standby time Tmax has elapsed before the completion of the stacking operation, At that time, the overlapping operation is stopped, and the next transport operation of the preceding medium P1 is started.

Hereinafter, the transport control executed by the computer 62 of the control unit 50 according to the first embodiment will be described with reference to the flowchart shown in FIG.
First, the processing in steps S31 to S36 in FIG. 22 is the same as the processing in steps S11 to S16 in FIG. 20 in the first embodiment. That is, when the printing of the preceding medium P1 is started, and the rear end of the preceding medium P1 passes through the first nip position NP1 and the first sensor 51 switches from ON to OFF, the superimposable condition is satisfied (S33). A positive determination is made), and the overlapping operation of feeding the succeeding medium P2 to the standby position Yw is started (S34). Then, at the determination time when the rear end of the preceding medium P1 is at the position of the last pass in the overlappable area LA, the overlapping operation is completed and the preceding medium P1 is stopped at the standby position Yw (Yes in S36). Judgment), after the skew removing operation is performed during the last pass (S39), and when the printing operation during the last pass is completed, the continuous feeding is performed (S40). On the other hand, if the succeeding medium P2 is in the stacking operation and has not stopped at the standby position Yw, the process proceeds to step S37.

  In step S37, the preceding medium P1 is put on standby until the stacking operation is completed, up to the standby time Tmax. The standby time Tmax is set to, for example, a predetermined value within the range of 0.1 to 1 second, but may be set to any other appropriate time. The computer 62 measures the elapsed time Tw (see FIG. 21) in which the preceding medium P1 is on standby by a built-in counter (not shown). The standby time Tmax is set so that the printing start timing of the succeeding medium P2 is shorter than the normal printing time of the succeeding medium P2 due to the continuous feeding. For this reason, if the continuous feeding can be performed by waiting for the standby time Tmax, the printing throughput is improved.

  In step S38, it is determined whether the standby time Tmax has elapsed. The computer 62 determines whether or not the elapsed time Tw in which the preceding medium P1 is on standby has reached the standby time Tmax. If the standby time Tmax has not elapsed, the process returns to step S36. Thereafter, the processing of steps S36 to S38 is repeated until the overlapping operation is completed in step S36 or the standby time Tmax has elapsed in step S38. That is, it waits until the overlapping operation is completed with the waiting time Tmax as a limit. Then, if the stacking operation is completed within the waiting time Tmax (Yes in S36), the skew removing operation is performed during the last pass (S39), and then the continuous stacking is performed (S40).

  On the other hand, if the waiting time Tmax has elapsed before the succeeding medium P2 completes the overlapping operation (Yes in S39), the medium interval creating operation is performed (S41). That is, after the preceding medium P1 is discharged, the subsequent medium P2 is searched for.

  For example, as shown in FIG. 21, when the first sensor 51 switches from ON to OFF, the feed motor 41 is switched from reverse drive to forward drive, and the overlapping operation is started. After the start of the superposition operation, the subsequent medium P2 is further accelerated, and the succeeding medium P2 is fed at a transport speed higher than the transport speed of the preceding medium P1. During this superimposition operation, when the preceding medium P1 is at the determination position that is the position of the last pass in the superimposable area LA (immediately before the start of the final transport operation), it is determined that the superimposition operation has not been completed. Even so, the start timing of the next (final) transport operation is delayed by waiting for the preceding medium P1, and the overlapping operation is continued during the standby. If the stacking operation is completed before the waiting elapsed time Tw reaches the standby time Tmax, the next transport operation is started. At this time, the second determination is performed at the determination time immediately before the start of the next transport operation, and it is confirmed that the succeeding medium P2 is stopped at the standby position Yw.

  After the final transport operation, after one or more transport operations depending on the print data PD, when the last pass printing operation is being performed, the feed motor 41 is driven in reverse rotation, and the leading end of the succeeding medium P2 rotates. The skew of the succeeding medium P2 is corrected by performing the skew removing operation against the stopped transport roller pair 33. Then, when the printing operation of the last pass is completed, the feed motor 41 and the transport motor 44 are driven synchronously as indicated by hatching in FIG. 21, and the preceding medium P1 and the succeeding medium P2 are maintained in an overlapping state. The sheets are continuously fed at the same conveying speed. As a result of the continuous feeding, the discharging operation of the preceding medium P1 and the cueing operation of the succeeding medium P2 are performed together, and the cueing of the succeeding medium P2 is performed at the printing start position. Thus, after the printing operation of the last line (last pass) on the preceding medium P1 is completed, the printing operation of the first line on the succeeding medium P2 can be started immediately. Therefore, printing throughput is improved.

As described above, according to 2 of the first embodiment, the following effects can be obtained.
(1-10) After starting the overlapping operation of the succeeding medium P2, the control unit 50 determines that the overlapping operation has been completed when the preceding medium P1 is at the determination position (immediately before the start of the final transport operation). After the printing operation of the last line is completed, the continuous feeding is performed. On the other hand, if the superposing operation is not completed, the control unit 50 continues the superposing operation within a range satisfying the condition of waiting for the preceding medium P1 within the standby time Tmax. After the end of the printing operation, the overlap continuous feeding is performed. If the condition of waiting for the preceding medium P1 within the waiting time Tmax is not satisfied, the control unit 50 does not perform the continuous feeding. Therefore, when the preceding medium P1 is at the determination position, even if the succeeding medium P2 has not completed the overlapping operation, the overlapping continuous feeding may be performed. Can be improved.

  (1-11) Even when the standby time Tmax has not elapsed, the standby of the preceding medium P1 is completed and the transport operation is started at the time when the overlapping operation of the preceding medium P1 is completed, so that the delay due to the standby can be minimized. it can. For this reason, the delay of printing on the preceding medium P1 can be minimized in spite of waiting for the preceding medium P1.

(3 of the first embodiment)
Next, 3 of the first embodiment will be described with reference to FIG. In the third embodiment, processing is performed by combining the first embodiment and the second embodiment. When the overlapping operation is not completed at the determination position, the control unit 50 continues the overlapping operation in 1 of the first embodiment, and completes the overlapping operation with a limit of the standby time Tmax in 2 of the first embodiment. One of the standby operations for waiting for the preceding medium P1 until the preceding medium P1 can be completed earlier is selected and executed. The continuation operation is an operation of continuing the superimposition operation of the succeeding medium P2 when the second superimposition continuous transfer execution condition as an example of the predetermined condition and the predetermined position condition is satisfied. The standby operation is an operation in which the preceding medium P1 waits until the overlapping operation is completed when the succeeding medium P2 can reach the standby position Yw within at least the standby time Tmax as an example of the predetermined condition.

Hereinafter, the transport control executed by the computer 62 of the control unit 50 will be described with reference to the flowchart shown in FIG. Note that FIG. 20 is referred to for the description of a part of the processing.
In FIG. 23, processing before step S16 is the same as the processing in steps S11 to S15 in FIG. 20 in the first embodiment. Further, the processing of steps S52 to S56 is the same as the processing of steps S17 to S21 in FIG. 20 in the first embodiment, and the continuous operation is performed by these processings. Further, the processing in steps S57 and S58 is the same as the processing in steps S37 and S38 in 2 of the first embodiment, and the standby operation is performed by these processings.

  Printing of the preceding medium P1 is started in step S11 of FIG. 20, and thereafter, when the rear end of the preceding medium P1 deviates from the first nip position NP1 and is detected by the first sensor 51 (Yes in S12), the overlapping operation. Is started (S13, S14). At the time of determination when the preceding medium P1 is at the position of the last pass in the overlappable area LA (immediately before the start of the final transport operation), if the stacking operation has been completed (Yes in S16), the skew during the last pass A picking-up operation is performed (S22), and after the printing operation of the last line is completed, overlapping continuous feeding is performed (S23).

  If it is determined in step S16 shown in FIG. 23 that the overlapping operation has not been completed, in step S51, it is determined which of the continuation operation and the standby operation can complete printing of the preceding medium earlier. Here, in the continuation operation, although the stacking operation is continued, if the next pass of the final transport operation is the last pass, the printing operation of the last pass is immediately started, or if the second overlap continuous feeding execution condition is not satisfied, At that point, the stacking operation must be stopped. In these cases, continuous feeding cannot be performed. On the other hand, in the standby operation, since the preceding medium P1 is made to wait until the overlapping operation is completed, the start timing of the transport operation of the preceding medium P1 is delayed by the standby time Tmax as a limit. The delay in the start time of the transport operation leads to a delay in the print completion time of the preceding medium P1. Therefore, in step S51, the computer 62 calculates the required time until the printing is completed while determining whether the continuous operation or the standby operation is performed by performing the continuous operation or the standby operation based on the print data PD in a simulation. Are compared, one of the continuation operation and the standby operation, which is earlier in print completion time, is selected. If it is a continuation operation that the printing of the preceding medium P1 can be completed earlier, the process proceeds to step S52, and thereafter, in steps S52 to S56, the same processing as in steps S17 to S21 in the first embodiment 1 is performed.

  That is, even if it is determined that the succeeding medium P2 has not completed the overlapping operation (No in S16), if the second overlapping continuous feeding execution condition is satisfied (Yes in S53), the overlapping operation is continued ( S54). If the overlapping operation can be completed before the printing of the last pass is started (negative determination in S52), the skew removing operation during the last pass (S22), and after the printing operation of the last line is completed, the overlapping operation is completed. Continuous feeding is performed (S23).

  On the other hand, if it is the standby operation that the printing of the preceding medium P1 can be completed earlier in step S51, the process proceeds to step S57, and thereafter, the preceding medium P1 is put on standby until the overlapping operation is completed within the standby time Tmax (S16). , S57, S58). By causing the preceding medium P1 to wait, the start time of the final transport operation is delayed, and accordingly, the determination time is also delayed. During the standby, the overlapping operation is continued. If the stacking operation is completed before the elapse of the standby time Tmax (Yes in S16), a second determination is made at a late determination time, and it is determined that the succeeding medium P2 is stopped at the standby position Yw. After confirmation, the final transport operation is started. After the final transport operation is completed, one or more transport operations are further performed depending on the print data PD, and then a skew removing operation is performed during the last pass (S22). This is performed (S23).

  In the superimposed continuous feeding, the discharging operation of the preceding medium P1 and the cueing operation of the succeeding medium P2 are performed together, and the subsequent medium P2 is cueed to the printing start position. Thus, after the printing operation of the last line (last pass) on the preceding medium P1 is completed, the printing operation of the first line on the succeeding medium P2 can be started immediately. Therefore, printing throughput is improved.

  For this reason, according to 3 of the first embodiment, the effects (1-1) to (1-11) of the first embodiment 1 and the effects (1-12), (1) of the second embodiment 2 -13), and the following effect can also be obtained.

  (1-12) After starting the superimposing operation of the succeeding medium P2, the control unit 50 determines that the preceding medium P1 is at the determination position. If the superposing operation is completed, the control unit 50 ends the printing operation of the last line. Later, overlapping continuous feeding is performed. On the other hand, if the overlapping operation has not been completed, the control unit 50 selects and executes one of the continuation operation and the standby operation that can complete printing of the preceding medium P1 earlier. When the continuation operation is performed, the positional relationship between the leading end position Y2 of the succeeding medium P2 and the trailing end position Y1 of the preceding medium P1 during the overlapping operation satisfies the second overlapping continuous transfer execution condition which is an example of the predetermined position condition. If so, the overlapping operation of the succeeding medium P2 is continued. On the other hand, when the standby operation is performed, if the succeeding medium P2 can reach the standby position Yw within at least the standby time Tmax, the preceding medium P1 is made to wait until the overlapping operation is completed. As described above, in the present embodiment, even if the overlapping operation has not been completed at the time of the determination, one of the continuation operation and the standby operation that can complete the printing of the preceding medium P1 earlier can be selected. The frequency is higher than 1 and 2 of the first embodiment, which can further contribute to the improvement of the printing throughput.

The first embodiment can be changed to the following modes.
In each of the above embodiments, a roller separation method using a pair of separation rollers may be used instead of the wall separation method. That is, as shown in FIG. 82, the printing device 12 of the multifunction peripheral 11 includes cassettes 21 and 22 as an example of a medium stacking unit that stacks a plurality of media P. The feed roller 28 is provided at a predetermined position, contacts the uppermost medium P among the plurality of media P stacked on the hopper plate 215 urged upward, and rotates the uppermost one of the media P. The medium P is sent out from the cassettes 21 and 22. The transport mechanism 24 includes a separation roller pair 95 that separates one medium P sent from the cassettes 21 and 22 from another medium. The separation roller pair 95 is disposed at a position where the medium sent from the cassettes 21 and 22 can be nipped. The medium P is separated from the other medium P by passing through the separation roller pair 95, and only one intermediate roller 30 is provided. Sent out to Further, when the feed motor 41 is driven in the normal rotation direction (CW direction), the clutch mechanism 42 is switched to the first switching position, and rotates the feed roller 28 and the intermediate roller 30 so that the medium can be conveyed. Rotate in the direction (forward direction). When the feed motor 41 is driven in the reverse direction (CCW direction), the clutch mechanism 42 is switched to the second switching position, and only the intermediate roller 30 is rotated in the forward direction with the feed roller 28 stopped. Rotate to. At the time of continuous printing for printing a plurality of pages, the feed motor 41 is driven to rotate forward during the transfer from the first page to the last page before the last, and the feed roller 28 and the intermediate roller 30 rotate in the forward direction. During conveyance of the medium P of the last page, the feed motor 41 is driven to rotate in the reverse direction, and the intermediate roller 30 rotates in the normal rotation direction with the feed roller 28 stopped.

  According to this configuration, after the rear end of the preceding medium P1 has deviated from the first nip position NP1 (final nip) of the intermediate roller 30, the control unit 50 moves the succeeding medium P2 from the cassette 21 to the transport speed of the preceding medium P1. A superimposition operation of conveying at a higher conveying speed than is performed. After the trailing end of the preceding medium P1 has deviated from the first nip position NP1, the overlapping operation of the succeeding medium P2 is started from the cassette 21, so that the interval between the preceding medium P1 at the start of the overlapping operation is compared. Long. For this reason, even when the succeeding medium P2 is in the middle of the superimposing operation, the frequency of performing the continuous superimposing operation is reduced when the determination is made at the timing immediately before the preceding medium P1 starts to be conveyed from the last pass in the superimposable area LA. Can be enhanced.

  In 2 of the first embodiment, when the first overlap continuous feeding execution condition is not satisfied (No in S36 of FIG. 22), the control unit 50 controls the preceding medium P1 to wait. It may be determined whether or not the succeeding medium P2 can reach the standby position Yw within the standby time Tmax which is an example of the predetermined time. As a result of the determination, if the succeeding medium P2 can reach the standby position Yw within the standby time Tmax, the superimposition operation is continued and the preceding medium P1 is made to wait until the completion, but the subsequent medium P2 is moved to the standby position within the standby time Tmax. If Yw cannot be reached, the superimposing operation is stopped at that point without waiting for the preceding medium P1. In this case, the determination as to whether or not the subsequent medium P2 can reach the standby position Yw within the standby time Tmax is performed, for example, as follows. Using the leading end position Y2 of the succeeding medium P2 and speed information on the catch-up feeding speed of the succeeding medium P2, a required time Tr (remaining time) until the succeeding medium P2 reaches the standby position Yw is calculated. If the required time Tr is equal to or less than the standby time Tmax (Tr ≦ Tmax), the control unit 50 causes the preceding medium P1 to wait until the overlapping operation is completed. On the other hand, if the required time Tr is not equal to or less than the standby time Tmax (Tr) > Tmax), the preceding medium P1 is not made to wait. In the case where the preceding medium P1 is put on standby, when the continuous overlapping operation is completed, the overlapping continuous feeding is performed after the printing operation of the last line of the preceding medium P1 is completed. On the other hand, when the preceding medium P1 is not made to wait, the overlapping operation is stopped, and after the printing operation of the last line of the preceding medium P1 is completed, the interval creating operation is performed. If the overlapping operation cannot be completed within the waiting time Tmax, the preceding medium P1 is not made to wait unnecessarily, so that the printing throughput can be further improved as compared with the second and third embodiments.

  In 2 and 3 of the first embodiment, if the first overlap continuous transfer execution condition is not satisfied, it is determined whether or not the second overlap continuous transfer execution condition is satisfied. A configuration may be adopted in which the medium P1 is made to stand by, and the preceding medium P1 is not made to stand by if the second overlap continuous feeding execution condition is not satisfied. According to this configuration, it is possible to avoid a delay of cueing of the succeeding medium P2 due to useless waiting of the preceding medium P1 as compared with 2 and 3 of the first embodiment.

  In 1 and 3 of the first embodiment, the second overlap continuous transfer execution condition as an example of the predetermined position condition includes a distance in a direction along a transfer path between the nip positions NP1 and NP2, a transfer speed of the preceding medium P1. It may be appropriately changed according to various parameters such as the catch-up feeding speed of the succeeding medium P2 and the interval between the preceding medium P1 and the succeeding medium P2 at the start of the superposing operation. The second overlapping continuous feeding execution condition may be a predetermined position condition including LL ≦ Y1 and Y1−Y2 ≧ 0, which includes that the rear end of the preceding medium P1 is in contact with or overlaps the front end of the succeeding medium P2. Alternatively, the predetermined position condition may be such that LL ≦ Y1 and Y1−Y2 ≧ −y (where y> 0) and the condition that the preceding medium P1 and the succeeding medium P2 are not separated from each other until the distance exceeds a predetermined distance y. Further, the condition of LL ≦ Y1 may be eliminated from the predetermined position condition. In this case, if the minimum overlapping amount is not secured at the time of the final determination after the completion of the continuous overlapping operation, the execution of the continuous overlapping feeding may be stopped.

  In the first and third embodiments, the predetermined position condition may change the predetermined amount (xmm) according to the rear end position Y1. For example, the predetermined amount is continuously or stepwise reduced as the rear end position Y1 of the preceding medium P1 is located on the upstream side. That is, when the rear end position is closer to the standby position Yw, the predetermined amount is set to a large value, and as the distance from the standby position Yw is increased, the predetermined amount is set to a smaller value. For example, LL ≦ Y1 and Y1−Y2 ≧ x, and the value of x is changed according to the rear end position Y1 of the preceding medium P1. In this case, the value of x is not limited to a positive value indicating that the preceding medium P1 and the succeeding medium P2 partially overlap with each other, and may include zero, or may include zero. May include a negative value that means that they are separated by a predetermined amount.

  In the first to third embodiments, the predetermined position is not limited to the lower limit position YL at which the minimum overlap amount can be secured, and may be changed to a suitable position on the upstream side in the transport direction Y from the standby position Yw. Good. However, the predetermined position is preferably a position within a range between an intermediate position in the direction along the transport path between the standby position Yw and the first nip position NP1 and the standby position Yw. Further, the predetermined position may be a standby position Yw.

  In the first to third embodiments, the process of determining whether or not the superimposable condition is satisfied may be performed after the superimposition operation. For example, before the start of the printing operation of the last pass or before reaching the determination position, the overlapping operation is started, and whether or not the overlapping operation is completed in a period from the stop at the standby position Yw to the start of the printing operation of the last pass. Is determined, and the determination of the success or failure of the superimposable condition is performed. Then, when both conditions are satisfied, the control unit 50 performs the overlapping continuous feeding.

  In 1 to 3 of the first embodiment, the determination time of the first overlap continuous feeding execution condition is determined in the final transport operation in which the rear end of the preceding medium P1 passes the lower limit position YL of the overlappable area LA. It is not limited to the timing immediately before the start. For example, the determination time may be a timing immediately before the start of the transport operation for transporting the preceding medium P1 to the transport position where the printing operation of the last pass is performed. Further, for example, the timing may be immediately before the start of the printing operation of the last pass. According to these configurations, the frequency of completing the stacking operation increases, and the frequency of performing the continuous stacking can be increased. At this time, with respect to the overlapping amount, if the overlapping operation is performed when the overlapping amount is equal to or more than the threshold, or if the overlapping operation is performed first and it is determined that the overlapping amount is the threshold at the time of determination, the appropriate overlapping amount is determined. Can be repeatedly fed. Further, other determination times may be appropriately selected, and may be determined, for example, during the printing operation of the second to last pass in the overlappable area LA or during the transport operation immediately before the final one. Further, for example, when the leading end of the preceding medium P1 is located at the start position of the carrying operation in which the rear end of the leading medium P1 passes through the nip position NP2 of the carrying roller pair 33, during the printing operation immediately before this carrying operation, or It may be during the previous transport operation.

  In the first to third embodiments, the overlappable area LA may be omitted. In this case, if the overlapping amount of the preceding medium P1 and the succeeding medium P2 is equal to or more than a predetermined amount, the overlapping operation may be continued to perform the continuous overlapping feeding.

  In the first to third embodiments, the start time of the continuous feeding is not limited to after the end of the printing operation of the last line. Overlapping continuous feeding may be started from the next transport operation after the end of the printing operation of the line immediately before the printing operation of the last line or two lines before the printing operation of the last line. In these cases, after the start of the continuous feeding, the conveying operation is performed by the continuous feeding until the preceding medium P1 reaches the position of the printing operation of the last line, and after the printing operation of the last line is completed, the printing of the succeeding medium P2 is started. Performs cueing by continuous feeding to the position. Further, when the leading end of the succeeding medium P2 has a positional relationship overlapping only the trailing margin area of the preceding medium P1 for the first time after the completion of the overlapping operation, the succeeding medium P2 during the printing operation on the preceding medium P1 at that time. May be performed, and the continuous feeding may be started from the transport operation to the printing position of the pass before the last pass. According to these configurations, a larger overlapping amount can be ensured, which can contribute to further improvement in the printing throughput.

  In the first to third embodiments, when the overlapping operation is continued after the determination, it is determined whether the overlapping operation is completed and the succeeding medium P2 is stopped at the standby position Yw. The determination may be abolished. Even if the succeeding medium P2 is stopped at a position upstream of the standby position Yw, if the skew removing operation is performed with a sufficient feeding amount, the skew is reliably corrected.

<Second embodiment>
In the present embodiment, one line is printed in one pass in which the print head 38 moves once in the scanning direction X. At this time, bi-directional printing is performed in the high-speed printing mode in which continuous feeding is performed. Also, when printing one row, if one row width uses some of the nozzle rows (all nozzles for one row), the printing position of the medium P in the transport direction Y with respect to the most downstream nozzle is used. And the uppermost stream nozzle reference that matches the print position of the medium P in the transport direction Y based on the uppermost stream nozzle.

  In the present embodiment, of the nozzle rows 381 (all nozzles for one row), a range of use nozzles (print nozzles) determined by the line width that can be used when printing one row (hereinafter also referred to as “use nozzle range”) ) Is based on a range selected by the number of used nozzles on the upstream side in the transport direction Y based on the most downstream nozzle # 1. That is, the range is such that the nozzles are continuous in the nozzle row direction by the number of used nozzles including the most downstream nozzle # 1. For example, when the number of used nozzles when printing one line is m, m continuous nozzles including the most downstream nozzle # 1 are the used nozzle range. The line width when printing one line, that is, the number m of nozzles used, is determined for each line according to the print content based on the print data PD. In the present embodiment, when one line is printed with a line width in which the number m of used nozzles is smaller than the total number Q of nozzles, the used nozzle range basically determined based on the most downstream nozzle # 1 is determined by the print head 38. In some cases, a nozzle shift process is performed in which the nozzle is shifted to the upstream side in the nozzle row direction (transport direction Y) to change to a usable nozzle range that does not include the most downstream nozzle # 1. By this nozzle shift processing, the frequency of establishment of the superimposable condition is improved.

  Basically, the printing operation is performed in the use nozzle range including the most downstream nozzle # 1. In a line narrower than the maximum line width to be used for printing, a nozzle shift process of moving (shifting) the used nozzle range to the upstream side in the transport direction Y is performed. In particular, in the present example, a range including the most upstream nozzle #Q is selected as the used nozzle range to be changed by the nozzle shift processing. The nozzles in the usable nozzle range are nozzles that can be used for printing, and whether or not the nozzles are actually used for printing depends on print data.

  Next, the nozzle shift processing will be described in detail with reference to FIGS. 24A, 24B, and 25. First, with reference to FIGS. 24A and 24B, a description will be given of a printing process in the first mode in which printing is performed based on the most downstream nozzle. In this embodiment, band printing for printing one line width in one pass of the print head 38 is performed.

  As shown in FIG. 24A, normally, a used nozzle range including a required number of continuous nozzles 382 on the upstream side with respect to the most downstream nozzle # 1 in the nozzle row 381 is selected. For printing a row having a bandwidth that requires use of all the nozzles # 1 to #Q of the nozzle column 381, the use nozzle range NA0 including all the nozzles # 1 to #Q is selected. In the example of FIG. 24A, printing is performed using the nozzles # 1 to #Q in the used nozzle range NA0 from the band B1 on the first row to the band Bn-1 on the n-1th row among the n rows for one page. .

  Then, as shown in FIG. 24B, the band Bn in the last row (n-th row) is printed using the first nozzle range NA1, which is a part of the nozzle range including the most downstream nozzle # 1 in the nozzle row 381. Is done. At this time, as shown in FIG. 24B, since the first nozzle range NA1 for printing the band Bn of the last row is located on the downstream side in the transport direction Y with respect to the printing unit 25, the transport position of the preceding medium P1 Also, it is necessary to set the printing unit 25 at a position closer to the downstream side in the transport direction Y in accordance with the first nozzle range NA1. For this reason, the length of the portion of the preceding medium P1 extending upstream along the transport path from the nip position NP2 of the transport roller pair 33 is relatively shorter than the trailing edge margin length Ybm. As a result, the overlap amount LP between the trailing margin BA of the preceding medium P1 and the leading end of the succeeding medium P2 becomes relatively short. For example, when the overlapping amount LP (that is, the rear end position Y1) is less than the lower limit LL, continuous overlapping feeding is not performed even if the rear end margin length Ybm is long enough to satisfy the superimposable condition. In other words, the rear end position Y1 of the preceding medium P1 at the time of the last pass printing operation changes depending on the band width (line width) of the last line determined according to the printing content of the preceding medium P1, so that it is determined whether or not the continuous feeding can be performed. Depends on the print content.

  Therefore, in the present embodiment, when printing a row using the nozzles 382 in a part of the nozzle row 381, the first nozzle range NA1 including the most downstream nozzle # 1 is moved to the upstream side in the transport direction Y. (Shift), and a nozzle shift process of switching to the second nozzle range NA2, which is a use nozzle range that does not include the most downstream nozzle # 1. In particular, in the present example, the second nozzle range NA2 is a used nozzle range including the most upstream nozzle #Q. For this reason, the shift amount of the used nozzle range by the nozzle shift processing is maximized.

  Next, the operation of the printing device 12 will be described. Hereinafter, with reference to FIG. 24A, FIG. 24B, FIG. 25, and FIG. Will be described. The computer 62 executes the program PR, for example, when receiving a print job from the host device 100. In the case of printing a plurality of sheets, first, the first medium is the preceding medium P1. When the preceding medium P1 is being printed, the second medium fed after the preceding medium P1 is the succeeding medium P2.

  First, in step S111, the preceding medium is fed. That is, as shown in FIG. 8, the computer 62 drives the feed motor 41 in the normal rotation direction (CW direction) (forward rotation drive), and feeds the preceding medium P1 by the rotation of the feed roller 28 and the intermediate roller 30. Send. During the feeding, a skew removing operation is performed in which the leading end of the preceding medium P1 is abutted against the transport roller pair 33 whose rotation is stopped, and the skew of the preceding medium P1 is corrected. Next, the computer 62 synchronizes the normal rotation drive of the feed motor 41 and the drive of the transport motor 44, and moves the preceding medium P1 to the printing start position by the intermediate roller 30 and the transport roller pair 33 rotating at the same transport speed. Cue.

  In step S112, it is determined whether the next path is the last path. This determination is made at a timing before the start of the transport operation for transporting the preceding medium P1 to the printing position of the next pass. If it is not the last pass, the process proceeds to step S113, and if it is the last pass, the process proceeds to step S120. It should be noted that this determination may be made at a timing until the printing operation of the next pass is started.

  In step S113, it is determined whether or not the overlapping operation has been performed. The computer 62 has a flag in the storage unit that sets “0” before the superposition operation is performed and “1” when the superposition operation is performed. It is determined that there is, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has not been performed, the process proceeds to step S114. If the overlapping operation has been performed, the process proceeds to step S117.

  In step S114, it is determined whether the first sensor has been switched from ON to OFF. That is, it is determined whether or not the rear end of the preceding medium P1 has deviated from the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 detects the trailing end of the preceding medium P1 and switches from ON to OFF, the process proceeds to step S115. If not, the process proceeds to step S117. When the first sensor 51 switches from ON to OFF, the computer 62 causes the first counter 81 to perform a counting process, and obtains the rear end position Y1 of the preceding medium P1 from the counted value.

  In step S115, it is determined whether or not the overlapping is possible. That is, it is determined whether or not a superimposable condition, which is a condition for performing continuous superimposition, is satisfied. Whether a superimposable condition including a margin condition such as LL ≦ Y1 <LU where the rear end position Y1 of the preceding medium P1 is located in the superimposable area LA and a print density condition that the print duty is equal to or less than a threshold is satisfied. Judge. If the superimposable condition is satisfied and the superimposition is possible, the process proceeds to step S116, and if not, the process proceeds to step S117.

  In step S116, an overlapping operation is performed. Specifically, the computer 62 drives the feed motor 41 to rotate in the normal direction, and feeds the succeeding medium P2 to the standby position Yw by rotation of the feed roller 28 and the intermediate roller 30. In this overlapping operation, the succeeding medium P2 is fed at a speed higher than the speed of feeding the preceding medium P1 being printed, and the feeding motor 41 is driven until the succeeding medium P2 reaches the standby position Yw. In the overlapping operation process, the computer 62 causes the second counter 82 to start a counting process when the first sensor 51 detects the leading end of the succeeding medium P2 and switches from OFF to ON. Of the front end position Y2 of. When the leading end position Y2 reaches the standby position Yw, the driving of the feeding motor 41 is stopped. As a result, the succeeding medium P2 stops at the standby position Yw. When completing the stacking operation, the computer 62 changes the value of the flag from “0” to “1”. Since the printing device 12 receives the print data for each pass and can store only print data for several passes in the storage unit, the trailing margin length and the leading margin length are set to the print data of the last pass of this page. In some cases, the configuration cannot be obtained until print data of the first pass of the next page is received. In this case, even if the first sensor 51 detects the rear end of the preceding medium P1, it is impossible to determine whether or not the superimposable condition is satisfied. In such a case, the determination of the success or failure of the superimposable condition should be made at the time when the necessary print data is obtained. By performing the operation, the succeeding medium P2 is caused to wait at the standby position Yw.

  In step S117, the carrying operation is performed to the printing position of the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. If the preceding medium P1 is already at the printing position of the first line immediately after the cueing, this transport operation is omitted.

  In step S118, a printing operation for one pass is performed. The computer 62 drives the carriage motor 48 to move the carriage 36 by one pass in the scanning direction X, and the print head 38 ejects ink droplets from the nozzles 382 based on print data during the one pass movement process. Then, a printing operation for printing an image for one pass on the preceding medium P1 is performed.

  In step S119, it is determined whether printing of one page has been completed. That is, it is determined whether or not the printing operation of all the lines to be printed on the preceding medium P1 has been completed. If the printing of one page has not been completed, the process returns to step S112, and if the printing of one page has been completed, the process proceeds to step S130.

  When returning to step S112, thereafter, the processing of steps S112 to S119 is repeated until the last pass is reached in step S112. At this time, if the superimposition operation has been performed (flag = “1”) (Yes in S113), the transport operation up to the next line (S117) and the printing operation for one pass in the next line (S118). Are performed substantially alternately, printing on the preceding medium P1 is advanced. In this printing operation, as shown in FIG. 24A, printing for one pass (one line) is performed in the use nozzle ranges NA0 and NA1 based on the most downstream nozzle # 1. Then, from the first pass to the printing of the (n-1) th pass immediately before the last pass, printing is performed line by line based on the most downstream nozzle. On the other hand, if the overlapping operation has not been performed (flag = “0”), the first sensor 51 is switched from ON to OFF before reaching the last pass (NO in S112) (an affirmative determination in S114), and the overlapping enabled condition is satisfied. Is satisfied (Yes in S115), the overlapping operation is performed (S116). Before reaching the last pass, if the first sensor 51 detects the rear end of the preceding medium P1 and the superimposable condition is satisfied at that time, the superimposing operation is performed (S116).

  When the printing operation of the pass before the last pass (the (n-1) th pass) is completed, the process returns to the step S112, and it is determined that the next pass is the last pass (the nth pass), so that the process proceeds to the step S120. .

  In step S120, it is determined whether or not the overlapping operation has been performed. The computer 62 determines whether or not the overlapping operation has been performed based on the value of the flag. That is, if the value of the flag is "1", it is determined that the overlapping operation has been performed, and if the value of the flag is "0", it is determined that the overlapping operation has not been completed. If the overlapping operation has not been performed, the process proceeds to step S117. If the overlapping operation has been performed, the process proceeds to step S121.

  If the overlapping operation has not been performed, the continuous continuous feeding cannot be performed. Therefore, the transport operation (S117) is performed to the printing position of the next last pass, and the printing operation for one line of the last pass (S118) is performed. When the printing operation of the last pass is completed in this way and the printing of one page of the preceding medium P1 is completed (YES in S119), in step S130, a discharging operation of discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. When the printing of the first preceding medium P1 is completed in this way and the first routine ends, in the next routine, the subsequent succeeding medium P2 becomes the preceding medium P1, and the third medium P becomes a new succeeding medium. It becomes P2. Then, the computer 62 executes the print control routine shown in FIG. 17 again for printing the next page, and in step S111, performs the feeding operation of the succeeding medium P2 as a new preceding medium P1. At this time, since the first precedent medium P1 has already been discharged, the discharge of the first precedent medium P1 and the feeding of the second precedent medium P1 are performed with an interval between the two media P. Done. On the other hand, if the next pass is the last pass (Yes in S112) and the overlapping operation has been performed (Yes in Step S120), the process proceeds to Step S121, and the following processing is performed.

  In step S121, it is determined whether the last row is to be printed using nozzles in a partial range of the nozzle row. When printing the last line using the nozzles 382 in a part of the nozzle array 381 in the last pass, the process proceeds to step S122, and the nozzles 382 in a part of the nozzle array 381 are not used. If the last line is to be printed using all the nozzles 382 in the column 381, the process proceeds to step S125.

  In step S122, the trailing edge margin length of the preceding medium is obtained. When the configuration is such that the print data PD is first received, the computer 62 obtains the trailing margin Ybm from the print condition information included in the header in the print data PD, or analyzes the print data PD to read the preceding medium P1. Of the last line of the last line and the medium size information to obtain the trailing margin Ybm. When the print data PD is sequentially received as print data for each pass, the computer 62 uses the print position and medium size information of the last line of the preceding medium P1 obtained from the print data of the last line. To obtain the trailing edge margin length Ybm.

  In the next step S123, it is determined whether or not the trailing edge margin length Ybm is equal to or smaller than a threshold value Y0. If the trailing edge margin length Ybm is equal to or smaller than the threshold value Y0 (Ybm ≦ Y0), the process proceeds to step S124. On the other hand, if the trailing edge margin length Ybm is not less than the threshold value Y0, that is, if the trailing edge margin length Ybm exceeds the threshold value Y0 (Ybm> Y0), the process proceeds to step S125.

  In step S124, the nozzle used for printing is changed. That is, the computer 62 performs a nozzle shift process of shifting a part of the nozzle row 381 used for printing (first nozzle range NA1) to the upstream side in the transport direction Y. In this case, the first nozzle range NA1 is shifted upstream to the position including the most upstream nozzle #Q in the transport direction Y to change to the second nozzle range NA2 including the most upstream nozzle #Q. At the same time, in accordance with the nozzle shift process, the transport amount in the next transport operation is shortened by a correction amount equal to the shift amount.

  In step S125, the transport operation is performed up to the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. At this time, if the nozzle used for printing has not been changed in step S124, the preceding medium P1 is transported by the initial transport distance. On the other hand, when the nozzle used for printing is changed by performing the nozzle shift process in step S124, the preceding medium P1 is transported by the corrected transport amount changed according to the shift amount of the nozzle shift process. That is, as shown in FIG. 25, when the printing operation of the (n-1) th pass is completed, the preceding medium P1 is transported by the transport amount after the correction. As a result, the preceding medium P1 is arranged at the transport position shown in FIG. 25 where printing can be performed using the nozzles 382 in the second nozzle range NA2 including the most upstream nozzle #Q.

  In step S126, a printing operation for one pass is performed. That is, the computer 62 drives the carriage motor 48 to cause the carriage 36 to move in the last pass, and prints the last line by ejecting ink droplets from the nozzles of the print head 38 during the movement process. At this time, when the print nozzle has not been changed by the nozzle shift processing, the last line is printed using the nozzle 382 in the first nozzle range NA1 including the most downstream nozzle # 1, as shown in FIG. 24B. That is, printing of the last line is performed based on the most downstream nozzle. The preceding medium P1 at the time of printing the last line is positioned relatively downstream in the transport direction Y with respect to the printing unit 25.

  On the other hand, when the nozzle used for printing by the nozzle shift process is changed, as shown in FIG. 25, the last line is printed using the nozzle 382 in the second nozzle range NA2 including the most upstream nozzle #Q. That is, printing of the last line is performed based on the uppermost stream nozzle. The preceding medium P1 at the time of printing the last line is located relatively closer to the upstream side in the transport direction Y with respect to the printing unit 25. As a result, the rear end position Y1 of the preceding medium P1 in FIG. 25 is located more upstream in the transport direction Y than the rear end position Y1 of the preceding medium P1 in FIG. I do. That is, the value of the rear end position Y1 of the preceding medium P1 in FIG. 25 is larger than the value of the rear end position Y1 of the preceding medium P1 in FIG. 24B.

  In step S127, it is determined whether or not the rear end position Y1 of the preceding medium satisfies the condition of LL ≦ Y1 <LU. LL ≦ Y1 <LU is one of the margin conditions among the superimposable conditions. Even if the value of the rear end position Y1 when the nozzle shift processing shown in FIG. 24B is not performed does not satisfy the condition of LL ≦ Y1 <LU, the rear end position shown in FIG. Since Y1 has a larger value, the frequency of satisfying the condition of LL ≦ Y1 <LU increases. If LL ≦ Y1 <LU is satisfied, the process proceeds to step S128. If LL ≦ Y1 <LU is not satisfied, the process proceeds to step S130. It should be noted that a configuration may also be adopted in which the success or failure of another condition among the superimposable conditions is also determined, and the process proceeds to step S128 when the superimposable condition is satisfied. In addition, it is confirmed in advance by calculation whether or not the rear end position Y1 of the preceding medium P1 during the last pass printing operation satisfies the condition of LL ≦ Y1 <LU. It may be configured to predict by calculation whether or not it is possible to change to the rear end position Y1 that satisfies the condition of ≦ Y1 <LU, and to perform the nozzle shift process when the change is possible.

  In step S128, a skew removing operation is performed. More specifically, when the drive of the transport motor 44 is decelerated or stopped so as to end the transport operation for transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the carriage motor 48 to perform the printing operation. While the driving of the transport motor 44 is stopped during the printing operation, the feeding motor 41 is driven to perform a skew removing operation of correcting the skew by abutting the leading end of the succeeding medium P2 against the transport roller pair 33 that is not rotating. . When the printing of the last pass is started during the superposing operation, the superposing operation and the skew removing operation are performed in one operation by directly abutting the leading end of the succeeding medium P2 to the transport roller pair 33 that is not rotating. Is also good.

  Then, in the next step S129, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the transport motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are The continuous feeding (hatched portion in FIG. 8) of feeding the subsequent medium P2 to the printing start position at the same feeding speed while maintaining the overlapping amount is performed.

  As shown in FIG. 8, when the printing of the last line of the first sheet is completed, the first medium P1 and the second medium P2 are placed in at least a part of the trailing margin of the preceding medium P1. P2 is conveyed together while maintaining the overlapping state, and the second medium P2 is moved to the print start position. In the case of this overlapping feeding system, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the transport amount when the cueing of the succeeding medium P2 to the printing start position is limited to the preceding medium P1. Is relatively small as compared with the transport amount in the normal feeding method in which the succeeding medium P2 is caught at an interval. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, in step S130, an operation of discharging the preceding medium is performed. At this time, the succeeding medium P2 is at the standby position Yw when the overlapping operation is performed, and is located upstream of the standby position Yw in the transport direction Y when the overlapping operation is not performed. Therefore, even if the transport motor 44 is driven to rotate the transport roller pair 33 and the discharge roller pair 34, only the preceding medium P1 is discharged, and the subsequent medium P2 waits at the position at that time.

  If there is a next page, after the discharging operation of the preceding medium P1 is completed, the routine is executed again with the succeeding medium P2 as a new preceding medium P1, and in step S111, the preceding medium P1 (the medium P of the next page) is fed. Perform the operation. At this time, since the next medium (previous succeeding medium P2) is stopped at the standby position Yw or a position slightly upstream from the standby position Yw, the feeding operation of the preceding medium P1 is started from the stopped position, and Of the preceding medium P1 at the print start position. If the rear end position Y1 is at a position that has passed the second nip position NP2 by a predetermined distance or more during the printing operation of the last pass, the skew removing operation of the succeeding medium P2 is performed during the printing operation of the last pass, and the last line of the preceding medium P1 is printed. After the end of the printing, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 may be performed with an interval therebetween. During the ejection of the preceding medium P1, the computer 62 starts driving the feed motor 41 at a timing when the rear end of the preceding medium P1 passes the transport roller pair 33 and a certain interval is secured, and the skew is removed. May be started to transport the subsequent medium P2 to the printing start position.

  In this way, the same number of routines as the number of printed sheets are repeatedly executed. At the time of printing the last sheet, since there is no succeeding medium P2 (next page) with only the preceding medium P1, the processing (S113 to S116, etc.) related to the overlapping operation is performed. skip. Then, for example, the transport operation (S117) and the printing operation (S118) for the last sheet of the medium P cueed in the previous continuous feeding (S129) are performed substantially alternately, and one page of printing is performed. . When the printing of one page is completed, the last medium P is discharged by a discharging operation (S130) (see also FIG. 8).

  As described above, according to the overlap feeding method of the present embodiment, after the printing of the preceding medium is completed, the trailing end of the preceding medium P1 and the leading end of the succeeding medium P2 are partially overlapped by the nozzle shift process. The frequency of carrying out the continuous feeding of the sheets is increased. In other words, in a row (a last row in this example) of printing using the nozzles 382 in a partial range of the nozzle row 381, the most upstream nozzle #Q is set from the first nozzle range NA1 including the most downstream nozzle # 1. The nozzle used for printing is changed to the included second nozzle range NA2. As a result, the transport position of the preceding medium P1 when the last line is printed is compared with the transport position when the nozzle shift process is not performed (FIG. 24B) by the shift amount on the upstream side in the transport direction Y (FIG. 24B). 25). For this reason, if the trailing margin Ybm is equal to or longer than a predetermined length (the sum of the distance from the position of the most upstream nozzle #Q to the second nip position and the minimum overlap amount Lmin) regardless of the print content, the nozzle shift processing is performed. Accordingly, the rear end position Y1 satisfies the condition not less than the lower limit LL of the overlappable area LA during the printing operation of the last pass. As a result, the frequency of the continuous feeding is increased, and the printing throughput is improved.

According to the second embodiment described in detail above, the following effects can be obtained.
(2-1) The control unit 50 moves the transport mechanism 24 that transports the medium and the plurality of nozzles 382 that eject and print ink onto the medium P transported by the transport mechanism 24 along the transport direction Y of the medium P. It controls the printing unit 25 having the nozzle rows 381 (an example of a nozzle group) arranged. When the trailing edge margin Ybm of the preceding medium P1 is equal to or smaller than the threshold Y0, the control unit 50 performs printing on at least one line (for example, the last line) of printing using the nozzles 382 in a partial range of the nozzle row 381. A part of the range to which the nozzle 382 belongs is moved to the upstream side in the transport direction from the position of the part of the range when the trailing margin Ybm exceeds the threshold Y0. As a result, when the nozzles 382 in the second nozzle range NA2 whose part of the range is moved are used, compared with the case where the nozzles 382 of the first nozzle range NA1 whose part of the range is not moved are used. The medium P <b> 1 is located closer to the upstream side in the transport direction Y by an amount corresponding to the movement of a part of the medium P <b> 1 to the upstream side in the transport direction Y. Accordingly, the transport position of the preceding medium P1 when printing is performed using the nozzles 382 in a part of the moved range is changed to the upstream side in the transport direction Y by the moved part of the range. When printing the last line, the rear end (upstream end) of the preceding medium P1 can be arranged at a position that is equal to or longer than the lower limit distance (that is, the lower limit position YL of the overlappable area LA) in the transport direction Y from the printing unit 25. As a result, when the continuous feeding cannot be performed due to the shortage of the overlapping amount, the necessary overlapping amount is secured between the preceding medium P1 and the succeeding medium P2, and the continuous feeding becomes possible, or the continuous continuous feeding is originally performed. Even if it is possible, the overlapping amount can be secured more widely. Therefore, it is possible to increase the frequency of performing the continuous superimposition without much depending on the print content of the preceding medium P1. As a result, the printing throughput can be further improved.

  (2-2) Roller pairs 33 and 34 capable of nipping the medium P are provided on the upstream side and the downstream side in the transport direction Y with respect to the printing unit 25. Even when the trailing end margin Ybm of the preceding medium P1 is relatively short, equal to or less than the threshold Y0, the printing unit of the preceding medium P1 when printing the last line is printed by using the second nozzle range NA2 of the nozzle row 381. The position in the transport direction Y (for example, the rear end position Y1) with respect to 25 can be positioned more upstream than in the case where the first nozzle range NA1 is used. As a result, when the last line is printed, the portion of the medium P that extends to the upstream side of the nip position NP2 of the transport roller pair 33 becomes longer, so that the frequency of performing continuous continuous feeding and the amount of overlapping are increased. Can be secured.

  (2-3) After printing the last line on the preceding medium P1, the control unit 50 maintains the state where the preceding medium P1 and the succeeding medium P2 partially overlap with each other until the succeeding medium P2 reaches the printing start position. Is performed. At this time, the trailing edge margin length Ybm is relatively short, equal to or less than the threshold value Y0, and continuous printing cannot be performed at the position of the preceding medium P1 when printing using the first nozzle range NA1 due to a shortage of the overlapping amount. However, by performing printing using the second nozzle range NA2, the preceding medium P1 can be positioned further upstream in the transport direction Y, so that continuous continuous feeding can be performed or the continuous continuous feeding can be performed. Can be secured more.

  (2-4) The control unit 50 determines that the length from the printing unit 25 to the rear end of the medium P when the last line is printed falls within the upper limit of the range in which continuous continuous feeding can be performed. The amount of shift in the transport direction to the second nozzle range with respect to one nozzle range in the upstream direction is determined. Therefore, it is possible to avoid a situation where the continuous feed cannot be performed because the rear end position Y1 has exceeded the upper limit position YU even though the nozzle shift process has been performed to change the nozzle range to be used. In other words, it is possible to reduce a situation in which the frequency of the repeated continuous feeding is lowered by changing the first nozzle range NA1 to the second nozzle range NA2.

  (2-5) The threshold value Y0 is a lower limit LL where the length from the printing unit 25 to the rear end Y1 of the medium P (preceding medium P1) when the last line is printed satisfies the condition that the continuous continuous feeding can be performed. Is set to the rear end margin length Ybm. Therefore, when the trailing edge margin length Ybm is equal to or less than the threshold value Y0, the second nozzle range is selected, and the distance from the printing unit 25 when printing the last line to the trailing edge Y1 of the medium P (preceding medium P1). Since the length is equal to or more than the lower limit LL that satisfies the condition for performing the overlapping continuous feeding, and satisfies the condition for performing the continuous overlapping feeding, the frequency of performing the continuous overlapping feeding can be increased.

  (2-6) When the trailing edge margin length Ybm is equal to or smaller than the threshold Y0, the control unit 50 changes the first nozzle range NA1 to the second nozzle range NA2 and satisfies the condition that the continuous overlapping feed can be performed. The second nozzle range NA2 is selected, and the first nozzle range NA1 is selected when the conditions for performing the continuous overlap feed are not satisfied. Therefore, when the conditions for enabling the continuous superimposition are not satisfied even when the nozzle range is changed, printing can be efficiently performed using the first nozzle range NA1. In the case where the condition is satisfied, the frequency of performing the continuous overlapping feed can be increased by selecting the second nozzle range NA2. Therefore, the printing throughput can be further increased.

  (2-7) When printing the last line on the preceding medium P1 using a part of the nozzle row 381, the control unit 50 prints the last line using the nozzle 382 in the second nozzle range NA2. , And perform continuous feeding. For example, even if the line width (bandwidth) of the last line is not known until the control unit 50 receives the print data of the last line, the preceding medium P1 is transferred to the printing unit 25 in the transport direction Y when printing the last line. Can be arranged at a position more upstream of. Therefore, it is possible to increase the frequency of performing the continuous feeding.

  (2-8) The first nozzle range NA1 is a part of the nozzle row 381 that includes the most downstream nozzle # 1 in the transport direction Y, and the second nozzle range NA2 does not include the most downstream nozzle # 1. It has a partial range. Here, in the case of the first nozzle range NA1 in which the range is determined on the basis of the most downstream nozzle, when the print data PD is generated by dividing the print data PD into one line by the printing device 12 or the printer driver 104 of the host device 100, the leading end is used. The print data may be generated by sequentially dividing the image of the print data PD by one line from the top without considering the margin length Ytm. On the other hand, in the case of the second nozzle range NA2 in which the range is determined based on the most upstream nozzle, when generating print data for each page by dividing the print data PD one line at a time, the leading edge margin length Ytm is set in addition to the print data PD. In consideration of this, it is necessary to generate print data while sequentially dividing the image one line at a time from the top. As a result, it is possible to increase the frequency of printing the last line in a state where the rear end of the medium is held between the pair of rollers on the upstream side, and increase the frequency of continuous feeding.

  (2-9) The first nozzle range is a part of the nozzle row 381 that does not include the most upstream nozzle #Q, and the second nozzle range is the one that includes the most upstream nozzle #Q of the nozzle row 381. Range of parts. When the trailing edge margin length Ybm exceeds the threshold value Y0, printing is performed on the medium P using a part of the nozzle rows 381 that do not include the most upstream nozzle #Q. When the trailing edge margin length Ybm is equal to or smaller than the threshold value Y0, printing is performed on the medium P using a part of the nozzle row 381 that includes the most upstream nozzle #Q. Therefore, as shown in FIG. 25, the trailing margin BA located upstream of the most upstream nozzle #Q in the preceding medium P1 can be maximized. As a result, the frequency at which the trailing end of the preceding medium P1 is pinched by the pair of transport rollers 33 arranged upstream of the print head 38 during printing of the last line is increased, or the necessary overlapping amount equal to or more than the minimum overlapping amount Lmin. And it is possible to increase the frequency of continuous feeding.

  (2-10) The control unit 50 controls the printing unit 25 (that is, the print head 38), and uses all the nozzles 382 in the range corresponding to the width of one row in the nozzle row 381 for printing. To perform band printing for printing one line. Therefore, when the nozzles used when performing band printing for each line with a line width corresponding to the print content are a part of the nozzle array 381, the nozzle range to be used is selected (changed). Is done. The rear end of the medium P when printing the last line can be positioned as much as possible upstream in the transport direction Y with respect to the printing unit 25, without being greatly dependent on the print content.

  (2-11) When the trailing edge margin length Ybm is equal to or smaller than the threshold Y0, the control unit 50 prints one of the lines printed on the medium P using a part of the nozzle row 381. The second nozzle range NA2 is selected. Therefore, the process of changing a part of the nozzle array 381 to be used only needs to be performed once per medium.

The above embodiment can be modified to the following forms.
-In the second embodiment, the print line when performing the shift process of moving the range of the nozzles used to the upstream side in the transport direction Y is not limited to the last line, and may be a line other than the last line. For example, as shown in FIG. 27, it may be one before the last row (the second row from the last row). In particular, in a configuration in which print data is received one pass at a time and only a few passes of print data can be stored in the storage unit, the print data of the last line is received, and the trailing margin length is determined. After the point in time, the nozzles to be used may be shifted in the first print line.

  In the second embodiment, as shown in FIG. 28A, the print line for selecting the second nozzle range NA2 by the nozzle shift process may be the first line. For example, if the configuration is such that the print data PD for one page can be received before the start of printing of one page, the trailing margin Ybm of the preceding medium P1 is acquired from the print data PD, and the trailing margin Ybm is smaller than the threshold Y0. , The second nozzle range NA2 may be selected from the first row. In the example of FIG. 28A, the second nozzle range NA2 including the most upstream nozzle #Q in the first row is selected, and as shown in FIG. 28B, the band B1 in the first row to the band Bn in the last row is based on the most upstream nozzle. Band printing is performed using the selected used nozzle range. In this case, when the trailing edge margin length Ybm is equal to or smaller than the threshold value Y0, the control unit 50 performs the nozzle shift processing on all the rows to be printed using the nozzles 382 in a partial range of the nozzle row 381. Is performed to select and print the second nozzle range NA2. That is, when the trailing edge margin length Ybm is equal to or smaller than the threshold Y0, the control unit 50 switches the printing of the page (preceding medium P1) from the most downstream nozzle reference to the most upstream nozzle reference from the first line to the last line. Are printed on the basis of the most upstream nozzle. Thus, selection of one of the first nozzle range NA1 and the second nozzle range, for example, switching from the most downstream nozzle reference to the most upstream nozzle reference may be performed in page units. According to this configuration, all the rows of the medium P are printed on the basis of the most upstream nozzle using the nozzle 382 in the range including the most upstream nozzle #Q in the nozzle row 381. The content of control at the time of control is relatively simple.

  In the second embodiment, the threshold is a constant, but the threshold may be a variable value. For example, assuming that the distance between the nozzle located at the most upstream position in the first nozzle range NA1 and the nip position NP2 of the transport roller pair 33 is Ln, the threshold Y0 is a value obtained by subtracting the distance Ln from the rear end margin Ybm (= Ybm-Ln). That is, the rear end margin length Ybm is set such that the rear end Y1 of the medium P when printing the last line is at a distance upstream of the printing unit 25 (for example, the print head 38) in the transport direction Y at least the lower limit distance LC. If the value is located, the first nozzle range NA1 is selected. If the value is located at a distance less than the lower limit distance LC, the second nozzle range NA2 is selected. Here, assuming that the distance between the second nip position NP2 and the print head 38 in the transport direction Y is Lh, the lower limit distance LC is represented by LC = LL + Lh using the value of the lower limit LL. As described above, a variable threshold value may be calculated by subtracting the distance between the most upstream nozzle in the first nozzle range NA1 before the nozzle shift process and the nip position NP2 of the transport roller pair 33. According to this configuration, it is possible to eliminate the determination as to whether or not the rear end position Y1 is equal to or less than the lower limit value LL after the completion of the overlapping operation, that is, whether or not the minimum overlapping amount Lmin is secured.

  In the second embodiment, the nozzle shift process of changing the first nozzle range NA1 of the nozzle array to the second nozzle range NA2 located on the upstream side in the transport direction Y is used in combination with the control of the continuous overlap feed. It is not limited to. If another effect on printing is obtained by increasing the distance from the printing unit 25 to the rear end Y1 of the medium P, the range of a part of the nozzle row used for printing is changed to the upstream side in the transport direction Y. A nozzle shift process may be performed. For example, when the last line is printed, the state in which the medium P is nipped by the transport roller pair 33 which is an example of the upstream roller pair means that the medium P is caused by the floating of the medium P from the support base 35. This is preferable for suppressing the displacement. Therefore, it is determined whether or not the rear end margin Ybm of the medium P is smaller than a threshold value equal to the minimum rear end margin length nipped by the pair of transport rollers 33 when the rear end Y1 of the medium P is printed at the time of printing the last line. to decide. When the trailing margin Ybm is less than the threshold value, the nozzle shift processing for changing the use nozzle range to the upstream side in the transport direction Y is performed. When the trailing margin Ybm is equal to or more than the threshold, the nozzle shifting processing is not performed. . According to this configuration, when printing the last line, the upstream end of the medium P is set to a distance equal to or more than the lower limit distance at which the nip of the rear end of the medium P by the conveying roller pair 33 can be nipped upstream from the printing unit 25 in the conveying direction Y. Can be placed more frequently. Therefore, it is possible to increase the frequency with which the last line can be printed in a state where the rear end of the medium P is sandwiched between the pair of transport rollers 33. The threshold value may be a constant or a value between the nozzle located at the most upstream position in the first nozzle range NA1 which is the range of the most downstream nozzle reference determined from the line width of the last line, and the nip position NP2 of the transport roller pair 33. The distance in the transport direction Y or a value obtained by adding a small margin (for example, a value in the range of 1 to 10 mm) to this distance. In addition, the nozzle shift process may be performed only on the last line, may be performed on any one of the first to last lines (for example, the line immediately before the last line), or may be further performed on one line. The processing may be performed on all lines from the line to the last line.

  In the second embodiment, the second nozzle range NA2 is not limited to the range including the most upstream nozzle #Q, and may be a range not including the most upstream nozzle #Q. Further, the first nozzle range is set so that the length from the nip position NP2 of the transport roller pair 33 to the rear end Y1 of the medium P upstream in the transport direction Y becomes a minimum required value (for example, a minimum overlap amount Lmin). A change amount (shift amount) from NA1 to the second nozzle range NA2 in the upstream direction in the transport direction Y may be determined. For example, the first nozzle range NA1 is shifted by a length that is insufficient before the rear end position Y1 reaches the lower limit LL of the overlappable area LA or a length obtained by adding a certain margin to this length. The nozzle range NA2 is determined. If the rear end position Y1 exceeds the upper limit position YU of the overlappable area LA to the upstream side when the second nozzle range NA2 including the most upstream nozzle #Q is changed, the shift is performed within the range not exceeding the upper limit position YU. You may decide the amount.

  In the second embodiment, the control unit may include the printer driver 104 of the host device 100. The printing device 12 may be a printing system including the printing device 12 and the printer driver 104 of the host device 100. The print control device is configured by a printer driver 104 installed in a computer of the host device. The control unit includes the control unit 50 of the printing device 12 and the print control device. The print control unit that constitutes the control unit executes the processes of steps S121 to S124, and transmits the print data obtained as a result of performing the nozzle shift process to the control unit 50 of the printing device 12.

  In the second embodiment, in the superimposition operation, the front end of the succeeding medium P2 is superimposed on the rear end margin BA of the surface (upper surface) of the rear end of the preceding medium P1 facing the print head 38. However, it may be stacked below. In the case of lower stacking, the leading edge margin of the succeeding medium P2 is overlapped on the surface (upper surface) opposite to the surface (upper surface) of the rear end of the preceding medium P1 facing the print head 38. Also, in the case of lower stacking, the execution timing of the skew removing operation and the continuous feeding is not necessarily required to be the last pass. The execution timing is determined by the current trailing edge position Y1 of the preceding medium P1 and the leading edge margin length Ytm of the succeeding medium P2. In other words, the leading end of the succeeding medium P2 is covered by the preceding medium P1 when the lower medium is overlaid, but the printing start position of the succeeding medium P2 only needs to be covered.

<Third embodiment>
Next, a third embodiment will be described with reference to the drawings. In the first and second embodiments, the print quality of the succeeding medium P2, which has been caught after the continuous feeding, may be degraded due to printing on a portion overlapping the rear end of the preceding medium P1. Under certain predetermined conditions, the continuous feeding is stopped to prevent a decrease in print image quality. Hereinafter, 1 and 2 of the third embodiment will be described.

(1 of the third embodiment)
First, a third embodiment will be described with reference to FIGS. The non-volatile memory 75 includes a print control program PR shown in the flowchart of FIG. The computer 62 operates according to the program PR read from the non-volatile memory 75 and controls the printing device 12.

  When the overlap feeding method is selected based on the print data PD, the control unit 50 constituting the printing apparatus 12 performs bidirectional printing in which printing is performed both at the time of forward movement and at the time of backward movement of the printing unit 25, and performs normal feeding. When the transport method is selected, unidirectional printing is performed in which printing is performed only in a single direction by the printing unit 25.

  Next, bidirectional printing will be described with reference to FIG. The printing unit 25 illustrated in FIG. 29 is a serial printing method that reciprocates in a scanning direction X that intersects (for example, is orthogonal to) the transport direction Y of the medium P. In FIG. 29, the leftward movement of the printing unit 25 is a forward movement, and the rightward movement is a backward movement. As shown in FIG. 29, in the bidirectional printing, the landing position D0 (print position) of the ink droplets discharged from the nozzle 382 of the print head 38 in the forward movement of the carriage 36, and the nozzle position of the print head 38 in the backward movement of the carriage 36 It is necessary to match the landing position D0 with the ink droplet ejected from the nozzle 382.

  In the high-speed printing mode, which is a printing mode in which the overlap feeding method is performed, the carriage 36 reciprocates at a high speed, and ejects ink droplets from the nozzles 382 of the print head 38 in both forward and backward movements. Bidirectional printing is performed in which printing is performed at high speed line by line in one movement (one pass). At this time, it is necessary to cause ink droplets ejected from the nozzles 382 of the print head 38 to land at the same target landing position in the scanning direction X between the forward movement and the backward movement of the printing unit 25.

  As shown in FIG. 29, when the carriage 36 moves forward at the moving speed Vc, the ejection start position is shifted earlier by the amount of displacement in the scanning direction X between the ejection start position of the carriage 36 and the landing position D0 in FIG. Must be set. Even when the carriage 36 moves backward at the moving speed Vc as shown in FIG. 29, it is necessary to set the ejection start position at a timing earlier by the amount of displacement in the returning direction.

  Here, the landing position is determined by parameters such as the moving speed Vc of the carriage 36, the gap PG between the nozzle and the medium P, and the ink discharge speed Vm. For this reason, the discharge start position at which the print head 38 discharges ink droplets is determined according to each of the above parameters. Here, in the printing of the first line on the succeeding medium P2 which has been searched for by the continuous continuous feeding, the overlapping of the preceding medium P1 and the succeeding medium P2 (shown by a two-dot chain line in FIG. 29) overlapping on the support base 35. When printing on a portion, a small gap PG2 is formed between the printing unit 25 and the succeeding medium P2.

  As shown in FIG. 29, the target landing position when there is one medium P is D0. When the print head 38 ejects ink droplets from the ejection start position shown in the drawing during the forward movement of the carriage 36 at a constant moving speed Vc, the ink droplets are ejected at the ejection speed Vm in the gravity direction Z and the forward movement direction of the print head 38. Fly in an oblique direction indicated by a composite vector with the moving speed Vc, and land at the target landing position D0. Also, when the print head 38 ejects ink droplets from the ejection start position in the drawing while the carriage 36 is moving at a constant moving speed Vc in the backward movement direction, the ink droplets are ejected from the ejection speed Vm in the gravity direction and It flies in an oblique direction indicated by a composite vector with the moving speed Vc in the forward movement direction, and similarly lands at the target landing position D0.

  However, when the gap PG1 when the medium P is one sheet becomes larger than the gap PG2 when two mediums P1 and P2 are overlapped, the same ejection start position from the print head 38 moving at the same constant moving speed Vc. When the ink droplets are ejected in the above, the ink droplets land on the surface of the succeeding medium P2 relatively quickly. Therefore, the ink droplet lands at the landing position D1 slightly shifted (toward the ejection start position) from the target landing position D0. At the time of the backward movement, similarly, it is shifted to the landing position D2 opposite to the landing position D1 with respect to the target landing position D0.

  For this reason, when printing is performed on a portion of the subsequent medium P2 that overlaps with the preceding medium P1 after the continuous feeding, print dots formed by landing of ink droplets are shifted in the scanning direction X. For this reason, in the present embodiment, measures are taken to reduce the displacement amount of the landing position, such as changing the ejection timing according to the gap PG2 of the portion where the media P1 and P2 overlap, or reducing the moving speed of the carriage 36. Has been given. If the moving speed is reduced as in the carriage 36 indicated by the two-dot chain line in FIG. 29, even if the medium P is ejected from the ejection start position aiming at the target landing position D0 when the medium P is one, the surface of the overlapping portion is The amount of deviation of the position D3 where the ink droplet has landed from the target landing position D0 can be reduced.

  Next, with reference to FIG. 30 to FIG. 37, a description will be given of conditions under which normal printing can be performed after continuous feeding of the preceding medium P1 and the succeeding medium P2. In FIGS. 30 and 34, the arrow shown on the band B in each row indicates the scanning direction X of the carriage 36 (that is, the print head 38) when the band B is printed. As shown in FIG. 16, after the continuous feeding of the preceding medium P1 and the succeeding medium P2, the carriage 36 moves in the scanning direction X and prints the first line on the succeeding medium P2. At this time, the leading end of the succeeding medium P2 is in a state of being superimposed on the trailing end (the trailing margin area) of the preceding medium P1. Bands B11 to B1n of the first to nth rows are printed on the preceding medium P1, and bands B21, B22,... From the first row are printed on the succeeding medium P2.

  First, as shown in FIG. 30, there are cases where the preceding medium P1 and the succeeding medium P2 are printed on the overlapping portion, and cases where they are not printed on the overlapping portion. When printing is performed on an overlapping portion, printing may not be performed normally. Therefore, conditions for normally printing are set. Hereinafter, a case where printing is performed on an overlapping portion of the medium P will be described.

  As shown in FIG. 30, the overlapping area Lp of the preceding medium P1 and the succeeding medium P2 is partially covered by the band B21 in the first row with respect to the succeeding medium P2. A portion corresponding to the image overlap amount PL in Y is printed on the overlap portion of the media P1 and P2.

  As shown in FIG. 31, in the printing operation of the last line on the preceding medium P1, only one sheet of the preceding medium P1 is supported on the support base 35, so that there is a space between the print head 38 and the medium P. Appropriate gaps are secured. Therefore, even if the band B1n is printed with the maximum width of one row (the width of the nozzle row length NL), the band B1n is printed normally.

  As shown in FIG. 32, when the band B21 in the first row is printed in the print area including the overlapping portion between the preceding medium P1 and the succeeding medium P2, since the overlapping portion has a thickness of two sheets, The gap between the print head 38 and the medium P is smaller by one medium than in the portion without the medium. Therefore, in the portion of the band B21 corresponding to the image overlap amount PL, as shown in FIG. 29, the ink droplets land on the positions D1 and D2 which are shifted from the target landing position D0 by ΔX in the scanning direction X. Become.

  Also, as shown in FIG. 32, the image overlap amount PL is determined by the trailing edge margin length L1 (= Ybm) of the preceding medium P1, the leading edge margin length L2 (= Ytm) of the succeeding medium P2, and the nip of the transport roller pair 33. Using the distance Ln between the position NP2 and the most upstream nozzle #Q, it is represented by PL = L1-L2-Ln.

  As shown in FIG. 33, the band B21 on the first line printed on the subsequent medium P2 has a first area SG printed on an overlapping portion with respect to the band width BW, and contacts the overlapping portion and the support 35. A second area VG printed on a portion inclined with respect to the portion and a third area LG printed on a portion where the succeeding medium P2 is in contact with the support 35 are included. The first area SG is printed under a gap smaller than the normal gap with the printing unit 25. Further, the third area LG is printed under a normal gap with the printing unit 25. Further, the second area VG is a gap between a gap when the first area SG is printed and a gap when the third area LG is printed, and the value of the gap gradually increases in the transport direction Y. Printed under a changing gap.

  In the first area SG, the gap at the time of printing is smaller by the thickness of one medium than in the third area LG, so that the printing dots formed by the ink droplets landing in the scanning direction X based on the gap difference are printed. Will shift. However, in the second region VG, the gap gradually changes in accordance with the difference in the position in the transport direction Y, so that the printing dots also gradually shift in the scanning direction X. For this reason, in the entire band B21, the displacement of the printing dots is relatively inconspicuous. This means that the whole or most of the second area VG in which the shift amount of the print dot in the scanning direction X gradually changes is included in the width BW of the band B21 of one row, and the shift of the print dot has continuity. Because. On the other hand, when the second region VG straddles the two rows of the bands B21 and B22 printed by the printing unit 25 moved in the direction opposite to the scanning direction X, the printing dots continuously shift between the bands B21 and B22. And the shift of the printing dots becomes conspicuous.

  On the other hand, the example shown in FIG. 34 is a case where the entire width of the band B21 for one line is printed in the overlapping area Lp of the preceding medium P1 and the succeeding medium P2. In the overlapping area Lp, the gap between the print head 38 and the medium P is reduced by one sheet, and therefore, as shown in FIG. 29, the ink droplet is shifted in the scanning direction X by ΔX with respect to the target landing position D0. Will land at the positions D1 and D2. Therefore, as shown in FIG. 34, the band B21 in the first row for the succeeding medium P2 is different from the band B22 in the second row printed in a portion other than the overlapping area Lp by the shift amount ΔB in the scanning direction X. Printing is shifted.

  The example shown in FIGS. 35 and 36 is a case where most of the band B21 for one line is printed in the overlapping area Lp of the preceding medium P1 and the succeeding medium P2. The ratio of the image overlap amount PL to the nozzle row length NL (that is, the maximum band width) is considerably high. In the band B21 in the first row shown in FIG. 36, the first area SG in which the printing unit 25 prints with a small gap in the overlapping portion of the media P1 and P2 occupies most of the band width BW. The second region VG where the gap gradually changes is located at the boundary between the band B21 in the first row and the band B22 in the second row. Further, the third area LG printed on the portion of the subsequent medium P2 that is in contact with the support 35 with an appropriate gap is included in the band B22 in the second row. Here, the band B21 in the first row and the band B22 in the second row are moved in the reverse direction of the print head 38 in the scanning direction X when they are printed. The displacement of the dots is relatively conspicuous on both sides of the boundary.

  For this reason, in the present embodiment, as shown in FIGS. 34 to 36, under the condition that the risk of print misalignment during bidirectional printing is high, the overlapping continuous feeding is performed as an avoidance process for avoiding a printing defect in which the print dot misalignment is conspicuous. I try to cancel. Here, when the ratio of the image overlap amount PL to the maximum bandwidth, which is the bandwidth BW corresponding to the nozzle row length NL, is relatively small, the band of one row tends to include all or most of the second region VG. It is in. Conversely, when the ratio of the image overlap amount PL to the maximum value of the bandwidth BW is relatively large, there is a tendency that the band of one row includes only a part of the second region VG. Therefore, as an index of a condition under which the dot shift is conspicuous, the magnitude of the ratio of the image overlap amount PL to the nozzle line length NL is used, and when the ratio of the image overlap amount PL to the nozzle line length NL exceeds the threshold value F, that is, PL / If the condition of NL × 100 (%)> F is satisfied, the avoidance processing is performed assuming that the risk of print misalignment is high. This condition is represented by PL> NL · F / 100. The threshold value F is a value of F (%) of the nozzle row length NL which is the length of the nozzle distribution area in the nozzle row. In this example, F = 50%. That is, the print misalignment risk is determined based on the condition of PL> NL / 2.

  In addition, as shown in FIG. 37, in a state where the head is caught by the continuous continuous feeding, the length of the portion of the subsequent medium P2 extending downstream from the second nip position NP2 does not reach the pressing roller 34C, and the pressing roller 34C may not be pressed. In this case, for example, if the leading end of the succeeding medium P2 is curled upward, the curled leading end comes into contact with the nozzle opening surface 38A of the print head 38, so that the succeeding medium P2 is stained with ink or the nozzle This may cause the ink meniscus to be destroyed and cause ink ejection failure. Therefore, the length L of the portion of the succeeding medium P2 after the continuous continuous feeding that extends downstream from the second nip position NP2 in the transport direction Y is the distance Lr from the second nip position NP2 to the axial center of the pressing roller 34C. If it is shorter than this, the continuous overlap feeding is stopped as an avoidance process for avoiding this type of printing failure.

  FIG. 38 is a graph showing margin conditions among the superimposable conditions. In the graph shown in FIG. 38, the vertical axis represents the trailing edge margin length L1 of the preceding medium P1, and the horizontal axis represents the leading edge margin length L2 of the succeeding medium P2. The overlapping permitted area PA in which overlapping continuous feeding is allowed under the overlapping possible condition is an image overlapping area of the first condition in which the rear margin length L1 satisfies LL ≦ L1 <LU and the front margin length L2 satisfies L2 ≧ Lr. The amount PL is a range that satisfies the second condition of PL <NL / 2 with respect to the nozzle row length NL. Further, the second condition forming the superimposable condition includes, as other conditions, a condition that the print duty is equal to or less than a threshold. The superimposable condition of the present embodiment is satisfied when all of the first condition and the second condition are satisfied.

  Next, the operation of the printing device 12 will be described. Hereinafter, with reference to FIGS. 8, 29 to 38, and the like, a description will be given of the transport control including the overlapping continuous feeding performed by the computer 62 in the control unit 50 executing the program PR shown in the flowchart of FIG. 39. . In FIG. 8, the feed motor 41 indicates the drive speed by distinguishing between forward rotation (CW) and reverse rotation (CCW), and the carriage motor 48 indicates the motor drive speed without distinguishing between forward rotation and reverse rotation. I have. Further, the transport motor 44 only drives forward.

  In the case of printing a plurality of sheets, first, the first medium is the preceding medium P1. When the preceding medium P1 is being printed, the second medium fed after the preceding medium P1 is the succeeding medium P2. During the printing of the first sheet, even if the second sheet is overlapped and fed with the first sheet, the leading edge of the second sheet is overlapped within the range of the trailing margin area of the first sheet. It is not printed on the overlapping portion of the second sheet with the second sheet. Therefore, the risk is not determined for the first sheet because the risk is low during the printing of the first sheet. On the other hand, the print target portion at the leading end of the second medium P (subsequent medium P2) cueed by the continuous feeding is the rear end of the first medium (preceding medium P1) preceding this. It may overlap with the margin area. The risk determination based on the overlap is performed by determining whether the first sheet and the second sheet are overlapped and continuously fed or not, and the rear end margin length of the first medium P and the front end margin length of the second medium P. Is performed using the above information. Hereinafter, similarly, the risk determination due to the overlap is based on the trailing edge margin length L1 of the preceding medium P1 and the leading edge margin length of the succeeding medium P2 used to determine whether the preceding medium P1 and the succeeding medium P2 are to be continuously fed. This is performed using the information of L2.

  In step S211, the preceding medium P1 is fed. In the case of printing a plurality of sheets, the first medium is the preceding medium P1. When the preceding medium P1 is being printed, the second medium fed next is the succeeding medium P2. That is, as shown in FIG. 8, the computer 62 drives the feed motor 41 in the normal rotation direction (CW direction) (forward rotation drive), and rotates the feed roller 28 and the intermediate roller 30 to rotate the preceding medium P1. Feed. During the feeding, a skew removing operation is performed in which the leading end of the preceding medium P1 is abutted against the transport roller pair 33 whose rotation is stopped, and the skew of the preceding medium P1 is corrected. Next, the computer 62 synchronizes the normal rotation drive of the feed motor 41 and the drive of the transport motor 44, and moves the preceding medium P1 to the printing start position by the intermediate roller 30 and the transport roller pair 33 rotating at the same transport speed. Cue. It should be noted that this determination may be made at a timing until the printing operation of the next pass is started.

  In step S212, it is determined whether the next path is the last path. This determination is made at a timing before the start of the transport operation for transporting the preceding medium P1 to the printing position of the next pass. If it is not the last pass, the process proceeds to step S213, and if it is the last pass, the process proceeds to step S223.

  In step S213, it is determined whether or not the overlapping operation has been performed. The computer 62 has a flag in the storage unit that sets “0” before the superposition operation is performed and “1” when the superposition operation is performed. It is determined that there is, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has not been performed, the process proceeds to step S214. If the overlapping operation has been performed, the process proceeds to step S217.

  In step S214, it is determined whether the first sensor has been switched from ON to OFF. That is, it is determined whether or not the rear end of the preceding medium P1 has deviated from the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 detects the rear end of the preceding medium P1 and switches from ON to OFF, the process proceeds to step S215, and if not, the process proceeds to step S217. When the first sensor 51 switches from ON to OFF, the computer 62 causes the first counter 81 to perform a counting process, and obtains the rear end position Y1 of the preceding medium P1 from the counted value.

  In step S215, it is determined whether or not overlapping is possible. That is, it is determined whether or not a superimposable condition, which is a condition for performing continuous superimposition, is satisfied. That is, the computer 62 determines whether or not the first condition (margin condition) (LL ≦ L1 <LU and L2 ≧ Lr) among the superimposable conditions is satisfied. If the first condition is satisfied and it is possible to overlap, the process proceeds to step S216, and if not, the process proceeds to step S217.

  In step S216, an overlapping operation is performed. Specifically, the computer 62 drives the feed motor 41 to rotate in the normal direction, and feeds the succeeding medium P2 to the standby position Yw by rotation of the feed roller 28 and the intermediate roller 30. In this overlapping operation, the succeeding medium P2 is fed at a speed higher than the speed of feeding the preceding medium P1 being printed, and the feeding motor 41 is driven until the succeeding medium P2 reaches the standby position Yw. In the overlapping operation process, the computer 62 causes the second counter 82 to start a counting process when the first sensor 51 detects the leading end of the succeeding medium P2 and switches from OFF to ON. Of the front end position Y2 of. When the leading end position Y2 reaches the standby position Yw, the driving of the feeding motor 41 is stopped. As a result, the succeeding medium P2 stops at the standby position Yw. When completing the stacking operation, the computer 62 changes the value of the flag from “0” to “1”. Since the printing device 12 receives the print data for each pass and can store only print data for several passes in the storage unit, the trailing margin length and the leading margin length are set to the print data of the last pass of this page. In some cases, the configuration cannot be obtained until print data of the first pass of the next page is received. In this case, even if the first sensor 51 detects the rear end of the preceding medium P1, it is impossible to determine whether or not the superimposable condition is satisfied. In such a case, the determination of the success or failure of the superimposable condition should be made at the time when the necessary print data is obtained. By performing the operation, the succeeding medium P2 is caused to wait at the standby position Yw.

  In step S217, the risk of misalignment in bidirectional printing is determined. Using the trailing margin length L1 of the preceding preceding medium P1 and the leading margin length L2 of the succeeding medium P2 used for the determination of the previous continuous feeding, an image overlapping amount PL to be printed out of the overlapping portion is obtained. . By determining whether or not the image overlap amount PL satisfies PL> NL · F / 100, the risk of printing misalignment is determined. Here, NL is the nozzle row length, and F (%) is the threshold value of F (%) of the nozzle row length NL, which is the length of the nozzle distribution area in the nozzle row. In this example, F = 50% is set as an example. In addition, although an appropriate value can be selected for F (%), it is preferably in the range of, for example, 30 to 80%.

  In step S218, it is determined whether the risk of misalignment in bidirectional printing is high. In this example, when PL> NL · F / 100 is satisfied, it is considered that the risk of misalignment of bidirectional printing is high. If the risk of misalignment in bidirectional printing is high, the process proceeds to step S219. If the risk of misalignment in bidirectional printing is not high (that is, low), the process proceeds to step S220.

  In step S219, a countermeasure for deviation is implemented. As a countermeasure for misalignment, the printing width (band width) of one line is changed to a width in which the misalignment due to bidirectional printing is reduced by image processing, or the ejection timing of the print head 38 is corrected to a timing at which the misalignment due to bidirectional printing is reduced. Or Further, a countermeasure for changing to unidirectional printing instead of bidirectional printing and a countermeasure for switching the moving speed of the printing unit 25 in the scanning direction X from the normal moving speed Vc to the low speed VL (<Vc) are taken. At least one of these measures is implemented as a shift measure. It should be noted that this countermeasure is implemented in a printing operation in which a printing area including at least a portion where the preceding medium P1 and the succeeding medium P2 overlap each other after the continuous feeding is printed.

  In step S220, the carrying operation is performed to the printing position of the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. If the preceding medium P1 is already at the printing position of the first line immediately after the cueing, this transport operation is omitted.

  In step S221, a printing operation for one pass is performed. The computer 62 drives the carriage motor 48 to move the carriage 36 by one pass in the scanning direction X, and causes the print head 38 to eject ink droplets from the nozzles 382 based on print data during the one pass movement. Then, a printing operation for printing an image for one pass on the preceding medium P1 is performed.

  In step S222, it is determined whether printing of one page has been completed. That is, it is determined whether or not the printing operation of all the lines to be printed on the preceding medium P1 has been completed. If the printing of one page has not been completed, the process returns to step S212. If the printing of one page has been completed, the process proceeds to step S232.

  When the process returns to step S212, thereafter, the processes of steps S212 to S222 are repeated until the last pass is obtained in step S212. At this time, if the superimposition operation has been performed (flag = “1”) (Yes in S213), the transport operation to the next line (S220) and the printing operation for one pass in the next line (S221). Are performed substantially alternately, printing on the preceding medium P1 is advanced. In this printing operation, even if the superimposable condition is satisfied (YES in S215), the first sensor 51 is not switched over from ON to OFF, and the first sensor 51 is not operated. When 51 is switched from ON to OFF (Yes in S214), the overlapping operation is performed (S216). If the first sensor 51 does not switch from ON to OFF even after the last pass, the overlapping operation is not performed.

  Further, when the preceding medium P1 is the first page, even if the succeeding medium P2 is supposed to be continuously overlapped, the leading end of the succeeding medium P2 overlaps the trailing margin area, so that printing is performed on the overlapping portion of the preceding medium P1. It will not be done. However, when the preceding medium P1 is the second or subsequent page, since the preceding medium P1 overlaps the trailing end of the preceding preceding medium, there is a possibility that the leading medium P1 is printed on the overlapping portion on the leading end side. The risk of bidirectional printing caused by printing on the overlapping portion is determined (S217), and if the risk of bidirectional printing is high (Yes in S218), a countermeasure is taken (S219). As a result, even if bidirectional printing is performed by the misalignment countermeasures, the occurrence of printing misalignment is suppressed by measures such as changing the boundary position of band printing, or the printing misalignment is reduced by switching to one-way printing. Generation is suppressed. If the preceding medium P1 is discharged to a position where printing of the overlapped portion of the preceding medium P1 and the preceding preceding medium is completed, the risk is determined to be low (negative determination in S218), and therefore, a countermeasure for deviation is taken. Instead, normal printing is performed.

  In this way, if the overlapping operation has not been performed between the first pass and the printing of the (n-1) th pass immediately before the last pass (flag = “0”), before the last pass (No in S212). Next, when the first sensor 51 is switched from ON to OFF (YES in S214) and the overlappable condition is satisfied (YES in S215), the overlapping operation is performed (S216). Before reaching the last pass, if the first sensor 51 detects the rear end of the preceding medium P1 and the superimposable condition is satisfied at that time, the superimposing operation is performed (S216).

  Then, when the printing operation of the pass before the last pass (the (n-1) th pass) is completed, the process returns to the step S212, and it is determined that the next pass is the last pass (the nth pass), so that the process proceeds to the step S223. .

  In step S223, it is determined whether or not the overlapping operation has been performed. The computer 62 determines whether or not the overlapping operation has been performed based on the value of the flag. That is, if the value of the flag is "1", it is determined that the overlapping operation has been performed, and if the value of the flag is "0", it is determined that the overlapping operation has not been completed. If the overlapping operation has not been performed, the process proceeds to step S217. If the overlapping operation has been performed, the process proceeds to step S224.

  If the overlapping operation has not been performed, the overlapping continuous feeding cannot be performed. Therefore, the carrying operation (S220) is performed to the printing position of the next last pass, and the printing operation for one line of the last pass (S221) is performed. When the printing operation of the last pass is completed in this way and the printing of one page of the preceding medium P1 is completed (YES in S222), in step S232, a discharging operation of discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. When the printing of the first preceding medium P1 is completed in this way and the first routine ends, in the next routine, the subsequent succeeding medium P2 becomes the preceding medium P1, and the third medium P becomes a new succeeding medium. It becomes P2. Then, the computer 62 again executes the print control routine shown in FIG. 39 for printing the next page, and performs the feeding operation of the succeeding medium P2 as a new preceding medium P1 in step S211. At this time, since the first precedent medium P1 has already been discharged, the discharge of the first precedent medium P1 and the feeding of the second precedent medium P1 are performed with an interval between the two media P. Done. On the other hand, if the next pass is the last pass (Yes in S212) and the overlapping operation has been performed (Yes in Step S223), the process proceeds to Step S224, and the following processing is performed.

  In step S224, the transport operation is performed up to the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line.

  In step S225, a printing operation for one pass is performed. More specifically, the computer 62 drives the carriage motor 48 to cause the carriage 36 to move in the last path, and prints the last line by ejecting ink droplets from the nozzles of the print head 38 in the course of the movement.

  In step S226, the trailing edge margin length of the preceding medium is obtained. In the case of a configuration in which the print data PD is sequentially received as print data for each pass, the computer 62 uses the print position and the medium size information acquired from the print data of the last line of the preceding medium P1 and the trailing edge margin length. Obtain L1. If the print data PD is received first, the computer 62 acquires the trailing margin L1 from the print condition information included in the header in the print data PD, or analyzes the print data PD and The trailing edge margin length L1 is obtained using the print position of the last line of the medium P1 and the medium size information.

  In step S227, the leading edge margin length of the succeeding medium is obtained. In the case of a configuration in which the print data PD is sequentially received as print data for each pass, the computer 62 uses the print position acquired using the print data of the first line of the succeeding medium P2 and the medium size information to obtain the leading end. The margin length L2 is obtained. When the print data PD is received first, the computer 62 obtains the leading edge margin length L2 from the print condition information included in the header in the print data PD, or analyzes the print data PD, and The leading edge margin length L2 is acquired using the print position of the first line of P2 and the medium size information.

  In step S228, a risk determination is performed. The computer 62 performs risk determination using the trailing margin L1 of the preceding medium P1 and the leading margin L2 of the succeeding medium P2. Specifically, the computer 62 uses the trailing edge margin length L1 of the preceding medium P1 and the leading edge margin length L2 of the preceding medium P1 to determine the position of the trailing edge of the preceding medium P1 and the trailing medium P2 when the continuous feeding is performed. The image overlapping amount PL to be printed out of the overlapping portion with the leading end is obtained. By determining whether or not the image overlap amount PL satisfies PL> NL · F / 100, the risk of print misalignment is determined. Here, F (%) is the same value (for example, 50%) as in step S217 described above, but may be a different value. One of the risk factors is that the print duty value exceeds the threshold. Here, the print duty value indicates the ratio (%) of the amount of ink per unit area printed on the medium P. In this example, the risk is determined to be high when the print duty value exceeds the threshold. Furthermore, when the length from the nip position NP2 at the leading end of the succeeding medium P2 to the downstream side in the transport direction Y at the end of the continuous stacking is within a specific range, the risk is determined to be high. In the present embodiment, whether or not the superimposable condition is satisfied is also set as one of the risk determination conditions. If the superimposable condition is not satisfied, the risk is determined to be high. If at least one of these risk conditions is satisfied, it is determined that the risk is high.

  In step S229, it is determined whether the risk is high. If the risk is high, the process proceeds to step S232, and the discharging operation for discharging the preceding medium P1 is performed without performing the overlapping continuous feeding. As a result, the preceding medium P1 is discharged, and thereafter, when the next routine is started, the preceding medium P1 is fed from the standby position Yw or a position upstream thereof. On the other hand, if the risk is not high (that is, if the risk is low), the process proceeds to step S230.

  In step S230, a skew removing operation is performed. More specifically, when the drive of the transport motor 44 is stopped to end the transport operation for transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the carriage motor 48 to perform the printing operation. The skew for correcting the skew of the succeeding medium P2 by driving the feed motor 41 and stopping the leading end of the succeeding medium P2 against the conveying roller pair 33 whose rotation is stopped while the driving of the conveying motor 44 in the printing operation is stopped. Perform the picking operation.

  Then, in the next step S231, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the conveying motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are Overlapping continuous feeding (hatched portion in FIG. 8) in which the sheets are conveyed together at the same conveying speed while maintaining the overlap amount is performed. As a result, the succeeding medium P2 is moved to the printing start position while maintaining the amount of overlap with the preceding medium P1. As shown in FIG. 8, when the printing of the last line of the first sheet is completed, the first medium P1 and the second medium P2 are placed in at least a part of the margin area of the preceding medium P1 so that the subsequent medium P2 The paper P is conveyed together while maintaining the state in which the leading ends overlap, and the second medium P2 is located at the print start position. In the case of this overlapping feeding system, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the transport amount when the cueing of the succeeding medium P2 to the printing start position is limited to the preceding medium P1. Is relatively small as compared with the transport amount in the normal feeding method in which the succeeding medium P2 is caught at an interval. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, if the stacking operation has not been performed (No in S223), since the continuous stacking cannot be performed, the carrying operation is performed to the next line (the printing position of the last pass) (S220). S221) is performed. Prior to this printing operation, the computer 62 determines the risk of misalignment of bidirectional printing (S217). If the risk of misalignment is high (Yes in S218), a printing operation with measures for misalignment is performed. If the risk of misalignment in bidirectional printing is low, a normal printing operation without measures for misalignment is performed. (S221).

  When printing of the last pass is completed and printing of one page of the preceding medium P1 is completed (YES in S222), in step S232, a discharging operation of discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. When the printing of the preceding medium P1 is completed in this way and one routine is completed, the succeeding medium P2 up to that time becomes the preceding medium P1, and the medium P of the next page becomes the new succeeding medium P2. Then, the computer 62 executes again the print control routine shown in FIG. 39 for printing the current page. At this time, when the continuous feeding (S231) is performed in the previous routine, since the preceding medium P1 has already been fed to the printing start position, the process of step S211 is omitted, and the process is started from the process of step S212. You. On the other hand, when the continuous feeding (S231) is not performed in the previous routine and the discharging operation (S232) is performed, the feeding operation of the preceding medium P1 is performed in step S211 to feed the preceding medium P1 to the printing start position. Then cue. At this time, since the previous preceding medium P1 has already been discharged, the current feeding of the preceding medium P1 is performed with an interval between the previous discharging of the preceding medium P1.

  If there is a next page, after the discharging operation is completed, the feeding operation of the medium P of the next page is performed in step S211. However, since the next medium (previous succeeding medium P2) is stopped at the position where the overlapping operation is slightly upstream of the standby position Yw, the preceding medium P1 (previous succeeding medium P2) is stopped from this stop position. Is performed, a new (second page) preceding medium P1 is located at the print start position. If the rear end position Y1 is at a position that has passed the second nip position NP2 by a predetermined distance or more during the printing operation of the last pass, the skew removing operation of the succeeding medium P2 is performed during the printing operation of the last pass, and After the end of the printing operation, the ejection of the preceding medium P1 and the cueing of the succeeding medium P2 may be performed with an interval therebetween.

  As described above, according to the repetitive feeding method of the present embodiment, the risk is determined and the repetitive continuous feeding is not performed when the risk is high, and the repetitive continuous feeding is performed when the risk is small. After the printing of the preceding medium is completed, the frequency of performing the continuous overlap feeding in which the rear end of the preceding medium P1 and the front end of the succeeding medium P2 are conveyed together in a partially overlapped state increases. That is, when a part of the nozzles in the nozzle row is used, a part of the nozzles including the most upstream nozzle is changed from the first used nozzle range using the part of the nozzle including the most downstream nozzle. The used nozzle is changed to the second used nozzle range using. As a result, the rear end margin length from the most upstream nozzle position to the rear end satisfies the superimposable condition that the superimposable length, which is the length of the portion on the upstream side of the nip position NP2, is equal to or more than the minimum margin length Lmin. become. On the other hand, if the nozzle has not been changed, the overlap margin length, which is the length of the rear end margin from the most upstream nozzle position to the rear end, which is the length of the portion upstream from the nip position NP2, is equal to or greater than the minimum margin length Lmin. Even if the overlapping possible condition is not satisfied, the overlapping possible condition is satisfied by performing the nozzle change, and the overlapping continuous feeding is performed. For this reason, the frequency of performing the continuous feeding increases, and the printing throughput improves.

According to the third embodiment described in detail above, the following effects can be obtained.
(3-1) When the superimposable condition as an example of the first condition under which the part of the preceding medium P1 and the part of the succeeding medium P2 can be superimposed is satisfied, the control unit 50 partially removes the preceding medium P1 and the succeeding medium P2. While the overlapped state is maintained, the continuous feeding is performed so that the subsequent medium P2 is conveyed together until it reaches the printing start position. However, if the printing unit 25 does not satisfy the second condition that enables normal printing on the succeeding medium P2 in a state where the printing unit 25 partially overlaps due to continuous feeding, the control unit 50 does not satisfy the second condition. Circumvention processing for avoiding the occurrence of a printing failure due to the above. Therefore, it is possible to reduce the frequency of occurrence of printing failure of the succeeding medium P2 due to the continuous feeding in which the succeeding medium P2 is conveyed to the printing start position while partially overlapping the preceding medium P1.

  (3-2) When the second condition for enabling printing without print disturbance is not satisfied, the control unit 50 performs an avoidance process for avoiding the occurrence of print disturbance. Therefore, it is possible to reduce the frequency of occurrence of disturbance in printing of the succeeding medium P2 due to the continuous continuous feeding in which the preceding medium P1 and the succeeding medium P2 are partially overlapped and conveyed together to the printing start position of the succeeding medium P2.

  (3-3) The control unit 50 controls the medium of at least one of the preceding medium P1 and the succeeding medium P2 and the medium of the printing unit 25 at the position when printing is performed on the succeeding medium P2 in which the printing unit 25 partially overlaps. If the relative positional relationship in the transport direction Y does not satisfy the second condition enabling normal printing, the avoidance process is performed. Therefore, it is possible to reduce the frequency of occurrence of printing failure of the succeeding medium P2 due to the continuous feeding.

  (3-4) The second condition is that the printing area where the printing unit 25 prints at least a part of the overlapping portion between the preceding medium P1 and the succeeding medium P2 is set to the maximum bandwidth (printable area) of the printing unit 25. On the other hand, the condition is that the ratio in the transport direction Y is less than a predetermined value. Then, when the second condition is not satisfied, the control unit 50 performs the avoidance processing. Therefore, it is possible to reduce the frequency of occurrence of printing failure (for example, printing disorder) of the succeeding medium P2 due to the continuous feeding.

  (3-5) As the avoidance process, the control unit 50 reduces the print area for the succeeding medium P2 to be printed by the printing unit 25 in the transport direction Y. The ratio of the printing area where the printing unit 25 prints on at least a part of the overlapping portion of the preceding medium P1 and the succeeding medium P2 to the printable area of the printing unit 25 in the transport direction Y decreases, and Even if printing is performed on at least a part, it is possible to reduce printing disorder.

  (3-6) The second condition is a distance Lr from the most downstream position (the most downstream nozzle # 1) of the printable area of the printing unit 25 to the pressing roller 34C as an example of a discharge roller, and a leading edge margin of the succeeding medium P2. The condition is that the difference from the length L2 does not take a value that causes the subsequent medium P2 to rub against the printing unit 25 as printing failure. Therefore, if the difference between the distance Lr and the leading edge margin length L2 takes a value that causes the subsequent medium P2 to rub against the printing unit 25 as a printing failure, an avoidance process is performed. Therefore, it is possible to reduce the frequency of occurrence of printing failure of the succeeding medium P2 (for example, rubbing failure of the succeeding medium P2 with respect to the printing unit 25) due to the continuous feeding.

  (3-7) When the second condition is not satisfied, the control unit 50 does not perform the continuous overlapping transmission as the avoidance processing. Therefore, it is possible to reduce the frequency of occurrence of printing failure of the succeeding medium P2 due to the continuous feeding.

  (3-8) The second condition is that the amount of ink per unit area when the printing unit 25 prints on the succeeding medium P2 is less than the threshold. When the amount of ink per unit area is equal to or larger than the threshold value, the control unit 50 does not perform continuous feeding. Therefore, it is possible to reduce the frequency of occurrence of printing failure of the succeeding medium P2 due to the continuous feeding.

  (3-9) The controller 50 performs the overlap continuous feeding even if the second condition is not satisfied, and performs the avoidance processing after the overlap continuous transmission if the second possible condition is not satisfied. Therefore, it is possible to reduce the frequency of occurrence of printing failure of the succeeding medium P2 due to the continuous feeding.

  (3-10) The printing apparatus 12 is a serial printer of a serial printing system in which the printing unit 25 prints on the medium P by reciprocating in the scanning direction X intersecting with the transport direction Y of the medium P. When the second condition is satisfied, the control unit 50 performs bidirectional printing for printing in both the forward movement and the backward movement of the printing unit 25. When the second condition is not satisfied, the control unit 50 performs the printing unit 25 Performs unidirectional printing in which printing is performed in only one of the forward movement and the backward movement. Therefore, even if the continuous feeding is performed, the occurrence frequency of the printing disturbance of the subsequent medium P2 can be reduced.

  (3-11) As the avoidance processing, the control unit 50 reduces the moving speed (carriage moving speed) of the printing unit 25 in the scanning direction X. Therefore, even if the continuous feeding is performed, the occurrence frequency of the printing disturbance of the subsequent medium P2 can be reduced.

(2 of the third embodiment)
Next, a second embodiment of the third embodiment will be described with reference to FIG. In 2 of the third embodiment, the risk determination is performed in the same manner as in 1 of the third embodiment. However, in order to receive information up to at least two pages ahead by the print data PD, the risk is determined in advance before the overlapping operation is performed. Each information of the trailing edge margin length L1 of the medium P1 and the leading edge margin length L2 of the succeeding medium P2 is acquired. Since it is possible to determine in advance whether or not to perform the superimposition operation, the superposition operation is not performed if the risk of performing continuous superimposition is high.

  Hereinafter, the printing apparatus 12 according to the second embodiment of the third embodiment will be described with reference to FIG. The printing control by the overlap feeding method performed by the computer 62 in the control unit 50 executing the program PR shown in the flowchart of FIG. 40 will be described. Note that FIGS. 29 to 38 are common to the second embodiment of the third embodiment, and the description will be focused on the contents of the different transport control.

  In the case of continuous printing of a plurality of sheets, first, the first medium is the preceding medium P1. When the preceding medium P1 is being printed, the second medium fed next is the succeeding medium P2. During the printing of the first sheet, the portion where the second succeeding medium P2 is overlapped with the first preceding medium P1 is a trailing margin area even if the second sheet is overlapped and fed with the first sheet. Therefore, printing is not performed on an overlapping portion of the first preceding medium P1 with the second sheet. Therefore, the risk is not determined for the first sheet because the risk is small during the printing of the first sheet. On the other hand, the overlapping portion of the leading end of the second medium P (subsequent medium P2) cueed by the continuous continuous feeding with the first preceding medium P1 is not necessarily the front end margin area. May also be printed. The determination of the risk of printing failure due to the overlap (hereinafter, also referred to as “overlap risk determination”) is based on the first medium P used to determine whether the first and second sheets are to be continuously fed. This is performed using the information on the trailing edge margin length and the information on the leading edge margin length of the second medium P. Hereinafter, similarly, this overlap risk determination is performed using the information on the trailing edge margin length L1 of the preceding medium P1 and the information on the leading edge margin length L2 of the succeeding medium P2 used in the determination as to whether or not continuous feeding is performed.

  In step S241, the preceding medium P1 is fed. This process is the same as step S211 in the first embodiment. As shown in FIG. 8, the computer 62 drives the feed motor 41 in the normal rotation direction (CW direction) (forward rotation drive), and feeds the preceding medium P1 by the rotation of the feed roller 28 and the intermediate roller 30. I do. During the feeding, a skew removing operation is performed in which the leading end of the preceding medium P1 is abutted against the transport roller pair 33 whose rotation is stopped, and the skew of the preceding medium P1 is corrected. Next, the computer 62 synchronizes the normal rotation drive of the feed motor 41 and the drive of the transport motor 44, and moves the preceding medium P1 to the printing start position by the intermediate roller 30 and the transport roller pair 33 rotating at the same transport speed. Cue.

  In step S242, it is determined whether the next path is the last path. This determination is made at the timing before the start of the transport operation for transporting the preceding medium P1 to the print position of the next pass for printing the next line. If it is not the last pass, the process proceeds to step S243, and if it is the last pass, the process proceeds to step S253.

  In step S243, the trailing edge margin length of the preceding medium is read. In the case of a configuration in which the print data PD is sequentially received as print data for each pass, the computer 62 uses the print position and the medium size information acquired from the print data of the last line of the preceding medium P1 and the trailing edge margin length. Obtain L1. If the print data PD is received first, the computer 62 acquires the trailing margin L1 from the print condition information included in the header in the print data PD, or analyzes the print data PD and The trailing edge margin length L1 is obtained using the print position of the last line of the medium P1 and the medium size information.

  In step S244, the leading edge margin length of the succeeding medium is read. In the case of a configuration in which the print data PD is sequentially received as print data for each pass, the computer 62 uses the print position acquired using the print data of the first line of the succeeding medium P2 and the medium size information to obtain the leading end. The margin length L2 is obtained. When the print data PD is received first, the computer 62 obtains the leading edge margin length L2 from the print condition information included in the header in the print data PD, or analyzes the print data PD, and The leading edge margin length L2 is acquired using the print position of the first line of P2 and the medium size information.

  In step S245, a risk determination is performed. The computer 62 performs risk determination using the trailing margin L1 of the preceding medium P1 and the leading margin L2 of the succeeding medium P2. Specifically, the computer 62 uses the trailing edge margin length L1 of the preceding medium P1 and the leading edge margin length L2 of the succeeding medium P2 to determine the position of the trailing edge of the preceding medium P1 and the trailing medium P2 when performing continuous feeding. The image overlapping amount PL to be printed out of the overlapping portion with the leading end is obtained. By determining whether or not this image overlap amount PL satisfies PL> NL · F / 100, the risk of deviation is determined. Here, F (%) is the same value as in step S217 described above, but may be a different value. One of the risk factors is that the print duty value exceeds the threshold. Here, the print duty value indicates the ratio (%) of the amount of ink per unit area printed on the medium P. In this example, the risk is determined to be high when the print duty value exceeds the threshold. Furthermore, when the length from the nip position NP2 at the leading end of the succeeding medium P2 to the downstream side in the transport direction Y at the end of the continuous stacking is within a specific range, the risk is determined to be high. Further, in the present embodiment, it is also determined as a risk whether or not the superimposable condition is satisfied. If the superimposable condition is satisfied, the risk is determined to be high. Here, the superimposable condition includes a margin condition (LL ≦ Y1 <LU) that the rear end position Y1 of the preceding medium P1 is within the superimposable area LA. If at least one of these risk conditions is satisfied, it is determined that the risk is high. The computer 62 determines whether or not the risk determination including the plurality of determination contents corresponds to, for example, a risk determination condition (overlapping permitted area) shown by a graph in FIG.

  In step S246, it is determined whether or not the overlapping operation has been performed. If the value of the flag in the storage unit is “1”, the computer 62 determines that the overlapping operation has been performed, and if the value of the flag is “0”, determines that the overlapping operation has not been performed. If the overlapping operation has not been performed (that is, if the overlapping operation has not been performed), the process proceeds to step S247. If the overlapping operation has been performed, the process proceeds to step S250.

  In step S247, it is determined whether the first sensor has been switched from ON to OFF. That is, it is determined whether or not the rear end of the preceding medium P1 has passed the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 switches from ON to OFF, the process proceeds to step S248. If the first sensor 51 does not switch from ON to OFF, the process proceeds to step S250. When the first sensor 51 switches from ON to OFF, the computer 62 causes the first counter 81 to perform a counting process, and obtains the rear end position Y1 of the preceding medium P1 from the counted value.

  In step S248, it is determined whether the overlapping risk is low. If the overlapping risk is low, the process proceeds to step S249. If the overlapping risk is not low (that is, high), the process proceeds to step S250.

  In step S249, an overlapping operation is performed. Specifically, when the first sensor 51 switches from ON to OFF (Yes in S247), the computer 62 drives the feeding motor 41 in the normal rotation direction, and rotates the feeding roller 28 and the intermediate roller 30 to rotate the feeding roller 41. The succeeding medium P2 is fed to the standby position Yw. In this feeding process, the computer 62 causes the first counter 81 to perform a counting process, thereby acquiring the rear end position Y1 of the preceding medium P1 from the counted value. In this overlapping operation, the normal rotation drive of the feed motor 41 is continued until the succeeding medium P2 reaches the standby position Yw at a transport speed higher than the transport speed of the preceding medium P1 during printing. Then, the succeeding medium P2 reaches the standby position Yw. When completing the stacking operation, the computer 62 changes the value of the flag from “0” to “1”. The printing device 12 receives the print data for each pass, and stores only a few passes of print data in the storage unit. Therefore, the trailing margin length and the leading margin length are printed in the last pass of this page. In some cases, the data cannot be acquired until the data and the print data of the first pass of the next page are received. In this case, even if the first sensor 51 detects the rear end of the preceding medium P1, it is impossible to determine whether or not the superimposable condition is satisfied. In such a case, the determination of the success or failure of the superimposable condition is performed at the time when the necessary print data is obtained. The superimposition operation is performed first before the determination, and the succeeding medium P2 is caused to wait at the standby position Yw. deep.

  In step S250, the transport operation is performed to the printing position of the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. For example, when the next line is the first line, the preceding medium P1 is located at the print start position (see FIG. 8).

  In step S251, a printing operation for one pass is performed. The computer 62 drives the carriage motor 48 to move the carriage 36 by one pass in the scanning direction X, and causes the print head 38 to eject ink droplets from the nozzles 382 based on print data during the one pass movement. Then, a printing operation for printing one pass on the preceding medium P1 is performed.

  In step S252, it is determined whether printing of one page has been completed. That is, it is determined whether the printing operation of all the lines of the preceding medium P1 has been completed. If printing of one page has not been completed, the process returns to step S242, and if printing of one page has been completed, the process proceeds to step S258.

  When the process returns to step S242, the processes in steps S242 to S252 are repeated until the last pass is reached in step S212. At this time, if the stacking operation has been performed (flag = “1”), the transport operation to the next line (S250) and the printing operation for one pass to the next line (S251) are substantially alternately performed. By doing so, printing on the preceding medium P1 is advanced. Also, even when the overlapping risk is low (Yes in S248), if the overlapping operation is not performed because the first sensor 51 has not switched from ON to OFF, the first sensor 51 switches from ON to OFF. (S247), the overlapping operation is performed (S249). In this manner, if the overlapping operation has not been performed (flag = “0”) between the first pass and the printing of the (n−1) th pass immediately before the last pass, before the last pass is reached (No in S242). In the judgment), the first sensor 51 is switched from ON to OFF (YES in S247) and if the risk of overlapping is low (YES in S248), the overlapping operation is performed (S249). If the first sensor 51 does not switch from ON to OFF even after the last pass, the overlapping operation is not performed.

  Further, when the preceding medium P1 is the first page, even if the succeeding medium P2 is supposed to be continuously overlapped, the leading end of the succeeding medium P2 overlaps the margin area at the trailing end, so that printing is performed on the overlapping portion. Never. However, when the preceding medium P1 is the second or subsequent page, since the leading end of the preceding medium P1 overlaps the trailing margin area of the preceding preceding medium, there is a possibility that printing will be performed on this overlapping portion. . However, as will be described later, in the present embodiment, when the risk is high, the overlapping continuous feeding is stopped by not performing the overlapping operation. Therefore, even if the printing is performed on the overlapping portion, the printing deviation is suppressed within an allowable range. Can be Note that when the preceding medium P1 is discharged to a position where printing of the overlapping portion between the preceding medium P1 and the preceding preceding medium is finished, normal printing is performed.

  On the other hand, when the printing operation of the (n-1) th pass before the last pass is completed, it is determined in step S242 that the next pass is the last pass. This determination is made during the period from the end of the printing operation of the pass (n-1st pass) immediately before the last pass (n-th pass) to the start of the transport operation of the preceding medium P1 to the printing position of the last pass. When the next pass is the last pass, the process proceeds to step S253.

  In step S253, it is determined whether or not the overlapping operation has been performed. The computer 62 determines whether or not the overlapping operation has been performed based on the value of the flag. That is, if the value of the flag is “1”, it is determined that the overlapping operation has been performed, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has been performed, the process proceeds to step S254. If the overlapping operation has not been performed (if the overlapping operation has not been performed), the process proceeds to step S250.

  If the stacking operation has not been performed, since the continuous stacking cannot be performed, the transport operation (S250) is performed to the next line (the printing position of the last pass), and the printing operation for one line of the last pass (S251) is performed. .

  In step S254, the transport operation is performed up to the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line.

  In step S255, a printing operation for one pass is performed. Specifically, the computer 62 drives the carriage motor 48 to cause the carriage 36 to move in the last pass, and prints the last pass line.

  In step S256, a skew removing operation is performed. More specifically, when the drive of the transport motor 44 is stopped to end the transport operation for transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the carriage motor 48 to perform the printing operation. The skew for correcting the skew of the succeeding medium P2 by driving the feed motor 41 and stopping the leading end of the succeeding medium P2 against the conveying roller pair 33 whose rotation is stopped while the driving of the conveying motor 44 in the printing operation is stopped. Perform the picking operation.

  Then, in the next step S257, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the conveying motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are Overlapping continuous feeding (hatched portion in FIG. 8) in which the sheets are conveyed together at the same conveying speed while maintaining the overlap amount is performed. As a result, the succeeding medium P2 is moved to the printing start position while maintaining the amount of overlap with the preceding medium P1. As shown in FIG. 8, when the printing of the last line of the first sheet is completed, the first medium P1 and the second medium P2 are placed in at least a part of the margin area of the preceding medium P1 so that the subsequent medium P2 The paper P is conveyed together while maintaining the state in which the leading ends overlap, and the second medium P2 is located at the print start position. In the case of this overlapping feeding system, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the transport amount when the cueing of the succeeding medium P2 to the printing start position is limited to the preceding medium P1. Is relatively small as compared with the transport amount in the normal feeding method in which the succeeding medium P2 is caught at an interval. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, if the superimposition operation has not been performed (No in S253), the transport operation is performed to the next line (the printing position of the last pass) (S254), and the printing of the last pass is completed (S255). When printing of one page is completed (Yes in S252), in step S258, a discharging operation for discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. When the printing of the preceding medium P1 is completed in this way and one routine is completed, the succeeding medium P2 up to that time becomes the preceding medium P1, and the medium P of the next page becomes the new succeeding medium P2. Then, the computer 62 executes again the print control routine shown in FIG. 40 for printing the current page. At this time, when the overlapping continuous feeding (S257) is performed in the previous routine, since the preceding medium P1 has already been fed to the printing start position, the feeding operation of step S241 is omitted, and the processing of step S242 is repeated. Be started.

  On the other hand, when the discharging operation (S258) is performed without performing the superimposed continuous feeding (S257) in the previous routine, the feeding operation of the preceding medium P1 is performed in step S241, and the preceding medium P1 is fed to the printing start position. Then cue. At this time, since the previous preceding medium P1 has already been discharged, the current feeding of the preceding medium P1 is performed with an interval between the preceding preceding medium P1.

As described above in detail, according to 2 of the third embodiment, the effects (3-1) to (3-11) of 1 of the third embodiment can be similarly obtained.
The third embodiment can be changed to the following modes.

  In 1 of the third embodiment, when it is determined that the risk is high in step S217 or step S228, the skew removing operation and the continuous continuous feeding are performed after the preceding medium P1 is transported to a position where the risk is low as the avoidance processing. May be. For example, when the first condition (for example, LL ≦ L1 <LU) is not satisfied, as the avoidance processing, before performing the superposition operation, the preceding medium P1 is transported to a position that satisfies the first condition, and then the continuous superimposition is performed. This avoids a printing error due to the continuous feeding while the stacking operation failed. When the second condition (for example, PL> NL · F / 100) is not satisfied, as the avoidance processing, the preceding medium P1 is conveyed to a position that satisfies the second condition, and then is continuously fed to perform printing. Avoid disturbances.

In the third embodiment, the process of determining whether or not the superimposable condition is satisfied may be performed before the superimposition operation.
In 2 of the third embodiment, the risk determination including the process of determining whether or not the superimposable condition is satisfied may be performed after the superimposition operation.

  In 1 and 2 of the third embodiment, the risk determination may employ only one of a plurality of conditions. For example, only PL> NL · F / 100 may be used, only the print duty value may be used, only the superimposable condition may be used, or only the head contact condition may be used. In addition, the risk determination may employ only two of the plurality of conditions or only three of the plurality of conditions.

  In 1 and 2 of the third embodiment, when the print duty value exceeds the threshold value under the print density condition which is one of the second conditions, an avoidance process for lowering the print duty value may be performed. In this case, as an avoidance process, the amount of ink ejected by the printing unit 25 may be reduced. When reducing the amount of ink, the dot size may be reduced. For example, a large dot is changed to a medium dot or a small dot. When reducing the dot size, the number of dots may be the same or may be increased. For example, by increasing the number of dot sizes that have been changed to be smaller, the amount of ink ejected may be reduced while maintaining image quality. In the latter case, the printer driver 104 or the control unit 50 may perform halftone processing for generating an image including large dots and halftone processing for generating an image not including large dots.

<Fourth embodiment>
Next, a fourth embodiment will be described with reference to the drawings. The first and second embodiments of the fourth embodiment detect the movement of the succeeding medium P2 in which the stacking operation may have failed, and stop the continuous feeding when detecting the movement in which the stacking operation may have failed. This is to avoid printing failure due to the continuous feeding while the stacking operation has failed. Hereinafter, 1 and 2 of the fourth embodiment will be described in order.

(1 of the fourth embodiment)
Next, a fourth embodiment will be described with reference to FIGS. This embodiment uses the sensor capable of detecting the succeeding medium P2 conveyed along the normal path during the superimposing operation and the third sensor 53 which is an example of the second sensor to detect the succeeding medium P2 during the superimposing operation. If the detection is successful, the continuous feeding is performed, but if the succeeding medium P2 is not detected, the continuous feeding is not performed.

  As shown in FIGS. 4 and 41, at a predetermined position on the transport path between the intermediate roller 30 and the transport roller pair 33 in the transport direction Y, the first sensor 51 and the second sensor 51 capable of detecting the presence or absence of the medium P are provided. The sensors 52 are arranged in this order from the upstream side in the transport direction Y. A third sensor 53 is provided between the first sensor 51 and the second sensor 52 in the direction along the transport path. In the present embodiment, the control unit 50 uses the detection signals of the first sensor 51 and the third sensor 53 for controlling the transport of the medium P.

  The third sensor 53 can detect the presence or absence of the medium P fed along a normal path in the stacking operation (catch-up feeding operation). The third sensor 53 of the present example is a contact sensor and has a lever 53A that can contact the medium P. When the lever 53A is at the position indicated by the solid line in FIG. 44, the third sensor 53 does not detect the medium P, but is pressed by the medium P and is disposed in the two-dot chain line in FIG. Is output. Note that the third sensor 53 may be an optical sensor instead of a contact sensor.

  As shown in FIG. 41, the third sensor is arranged at a position on the conveyance path between the intermediate roller 30 and the conveyance roller pair 33. In addition, as shown in FIGS. 4 and 41, the third sensor 53 is disposed at a position on the transport path between the first sensor 51 and the second sensor 52. The third sensor 53 is a sensor that can detect the succeeding medium P2 being conveyed on the normal path of the stacking operation and cannot detect the succeeding medium P2 conveyed on a path other than the normal path. The control unit 50 illustrated in FIG. 7 performs the continuous feeding when the third sensor 53 detects the subsequent medium P2, and does not perform the continuous feeding when the third sensor 53 does not detect the subsequent medium P2. That is, when the control unit 50 detects the succeeding medium P2 being conveyed along the normal path during the superposition operation, the control unit 50 performs the superimposition continuous feeding after finishing the printing on the preceding medium P1 after the completion of the superposition operation. On the other hand, if the control unit 50 does not detect the succeeding medium P2 because it has been conveyed out of the normal path during the stacking operation, the subsequent stacking and continuous feeding is stopped.

  The guide member 55 shown in FIG. 41 is the same as in the first to third embodiments. That is, as shown in FIG. 41, a guide member 55 for guiding the medium P is disposed at a position slightly downstream from the nip portion (first nip position NP1) between the intermediate roller 30 and the second driven roller 32. Have been. The guide member 55 is configured such that the feeding path (ejection path) of the medium P sent from the first nip position NP1 is higher (opposite to the gravity direction Z) than the tangential direction of the intermediate roller 30 at the first nip position NP1. The medium P is guided so as to point to the position. In this example, the guide member 55 is arranged in a posture in which its guide surface (upper surface) is horizontal, and its sending-out guide direction is horizontal as an example. A ceiling having an inclined guide surface 56 </ b> A that becomes lower toward the downstream side in the transport direction Y above the transport path from the first nip position NP <b> 1 of the intermediate roller 30 to the second nip position NP <b> 2 of the transport roller pair 33. A wall 56 is arranged. The medium guide direction of the guide member 55 intersects the guide surface 56A. The medium P sent out at a feed speed higher than the transport speed of the preceding medium P1 is guided by the guide member 55 in a direction obliquely hitting the guide surface 56A (for example, in a horizontal direction), and then along the guide surface 56A. The sheet is conveyed toward the conveying roller pair 33 along a conveying path that keeps the upper limit position as much as possible. For this reason, the leading end of the succeeding medium P2 overlaps the trailing end of the preceding medium P1 from above.

  Even if the succeeding medium P2 is conveyed along an abnormal path deviating from the guide surface 56A, if the third sensor 53 is turned on due to the flutter of the succeeding medium P2 during the overlapping operation, the overlapping operation of the succeeding medium P2 is performed on an abnormal path. Is performed, it is erroneously detected that the overlapping operation has been performed on the normal path. When the superimposition operation of the succeeding medium P2 is performed on an abnormal path, the succeeding medium P2 is to be superimposed on the preceding medium P1 from the upper side. The overlapping operation may fail due to the rear end colliding with the front end of the succeeding medium P2. Then, when the continuous feeding is performed in a state where the stacking operation has failed, in the case of the failure where the stacking operation has failed, the content to be printed on the succeeding medium P2 is printed in the trailing margin of the preceding medium P1. , Printing of the preceding medium P1 fails. Further, if the continuous feeding is performed in a state where the rear end of the preceding medium P1 and the front end of the succeeding medium P2 collide and abut against each other, it causes a medium jam (paper jam or the like). Therefore, in order to avoid this type of printing failure and medium jam, the third medium is conveyed along a normal path along the guide surface 56A regardless of the flutter during the overlapping operation of the subsequent medium P2. A configuration is adopted in which the sensor 53 is turned on and the third sensor 53 remains off if the sheet is conveyed along an abnormal path away from the guide surface 56A.

  Therefore, in the present embodiment, the guide member 55 guides the succeeding medium P2 in the overlapping operation in a cross-section taken in the width direction X intersecting the transport direction Y so as to be convexly curved upward (the side facing the guide surface). Then, a concave portion 564 (see FIG. 43) into which a convexly curved portion can enter is provided on the guide surface 56A. The third sensor 53 is arranged at a position where only the curved portion that has entered the concave portion 564 can be detected.

  The guide member 55 shown in FIG. 42 is a cross section taken along line AA in FIG. As shown in FIG. 42, the guide member 55 includes a plate-shaped bottom plate portion 55A, a pair of side wall portions 55B protruding upward at both end portions in the width direction X of the bottom plate portion 55A, and a pair of side wall portions 55B. A projection 55C as an example of a projection projecting upward at a substantially central position. A pair of concave portions 55D arranged in the width direction X is formed between the pair of side wall portions 55B at positions on both sides of the protruding portion 55C. The subsequent medium P2 at the time of the stacking operation, which is conveyed to the downstream side from the position nipped between the intermediate roller 30 and the second driven roller 32, has a pair of side wall portions 55B and two pair of side wall portions 55B. The projections 55C sandwiched between the recesses 55D form three mountain-shaped waves in the width direction X due to the unevenness formed on the upper surface side of the guide member 55. As these three mountain-shaped waves are conveyed downstream, they change into one large mountain-wave, and are guided along the guide surface 56A while maintaining a convexly curved shape.

  As shown in FIG. 4, the third sensor 53 is disposed at a substantially central position in the width direction X of the ceiling wall portion 56, and is disposed at substantially the same position as the intermediate roller 30 in the width direction X. Therefore, the third sensor 53 is arranged at substantially the same position as the guide member 55 in the width direction X.

  As shown in FIG. 43, the ceiling wall portion 56 has a plate-shaped substrate portion 561 and a plurality of extending downwardly from the substrate portion 561 at a predetermined interval in the width direction X (only two are shown in FIG. 43). And a plurality (four in the example of FIG. 4) of second extensions that are arranged near the third sensor 53 and extend downward with a shorter length than the first extension 562. And a projection 563. For this reason, between the pair of first extending portions 562 located on both sides of the arrangement region of the second extending portion 563 below the third sensor 53, each extending portion 562, 563 in the width direction X. The concave portion 564 having an opening width considerably larger than the interval is formed so as to open downward. Note that a part of the guide surface 56A is formed by the distal end surface of the first extension portion 562.

  The third sensor 53 includes a lever 53A rotatably supported around a pin 53C inserted and supported by a pair of support portions 565 protruding upward from the upper surface of the substrate portion 561, and an upper end of the lever 53A. An optical sensor 53B that switches on and off in accordance with the rotation position of the lever 53A is provided as a detection target.

  As shown in FIGS. 43 and 44, the lever 53A of the third sensor 53 is slightly lower than the guide surface 56A formed by the lower end surface of the first extension portion 562 at the standby position indicated by the two-dot chain line in FIG. It is in a protruding state. The third sensor 53 is in the off state in which the medium P is not detected when the lever 53A is at the standby position, and in order to switch from the off state to the on state in which the medium P is detected, the third sensor 53 detects the state indicated by a solid line in FIG. It is necessary to rotate to the position. In order to rotate the lever 53A to the detection position, the medium P needs to enter the concave portion 564 in a convexly curved shape as shown by a solid line in FIG. For this reason, the succeeding medium P2 conveyed along a normal path while maintaining the peak wave generated when guided by the guide member 55 can enter the recess 564 and rotate the lever 53A to the detection position. It has become. On the other hand, the subsequent medium P2 that has not been conveyed along the normal route does not enter the concave portion 564 as shown by the two-dot chain line in FIG.

  When the succeeding medium P2 is conveyed along the guide surface 56A along the normal path shown by the solid line in FIG. Is turned to the detection position, the third sensor 53 switches from off to on. On the other hand, when the succeeding medium P2 is conveyed along an abnormal path shown by a two-dot chain line in FIG. The two-dot chain line indicates that the third sensor 53 remains OFF because the subsequent medium P2 cannot enter the concave portion 564.

  In the example shown in FIG. 45, when the first sensor 51 is switched from ON to OFF during printing of the first or second sheet, the feed motor 41 is switched to high-speed driving, and the overlapping operation of the subsequent medium P2 is performed. Be started. As shown in FIG. 42, the succeeding medium P2 is conveyed along the guide surface 56A (see FIG. 44) while maintaining an upwardly convex chevron shape formed in the process of being guided by the guide member 55. At this time, if the succeeding medium P2 is conveyed along a normal path, the chevron-shaped portion of the leading end of the succeeding medium P2 enters the concave portion 564 and rotates the lever 53A during the stacking operation (see FIG. 43), the third sensor 53 switches from OFF to ON, as shown in FIG. If the succeeding medium P2 during the stacking operation flutters even when being conveyed along a normal path, the third sensor 53 may be repeatedly turned ON and OFF. When the third sensor 53 happens to be turned OFF, the computer 62 may erroneously determine that the detection result is to be determined. For this reason, as shown in FIG. 45, after the first sensor 51 that has detected the leading end of the succeeding medium P2 switches from OFF to ON after the start of the overlapping operation, the computer 62 turns on when the third sensor 53 is turned on. The value indicating that the stacking operation of the medium P2 has been performed on the normal path is written in the flag. Therefore, even if the tip of the succeeding medium P2 flaps and the third sensor 53 is turned off, the computer 62 can recognize from the value of the flag that the succeeding medium P2 has been conveyed along a normal route.

  Then, as shown in FIG. 45, if the third sensor 53 is turned on in the middle of the overlapping operation (that is, flag = 1), it is determined that the overlapping operation has succeeded, while the third sensor 53 is in the middle of the overlapping operation. Is not ON (that is, flag = 0), it is determined that the overlapping operation has failed. If the succeeding medium P2 during the stacking operation is being conveyed along an abnormal path, even if the succeeding medium P2 flaps, the lever 53A of the third sensor 53 in the depth of the concave portion 564 is pushed until the lever 53A is turned ON. The computer 62 does not make a misjudgment because there is no such event.

  Here, during the overlapping operation, there is a possibility that the rear end of the preceding preceding medium P <b> 1 flaps and pushes the lever 53 </ b> A in the concave portion 564 to turn on the third sensor 53. In this case, even if the succeeding medium P2 is conveyed along an inappropriate route away from the guide surface 56A, the computer 62 turns ON the third sensor 53 due to the fluttering of the rear end of the preceding medium P1. May be recognized as having been transported along a normal route.

  Therefore, as shown in FIG. 46, a detection range SA of a predetermined distance including the detection position of the third sensor 53 is set on the transport path, and only when the leading end of the succeeding medium P2 is located within the detection range SA, The three sensors 53 are enabled. The lower limit (the leftmost entrance position in FIG. 46) and the upper limit (the rightmost exit position in FIG. 46) of the detection range SA are set as follows. Here, the lower limit is the upstream limit position in the transport direction Y of the detection range SA, and the upper limit is the downstream limit position in the transport direction Y of the detection range SA. The lower limit of the detection range SA is set to a position where the rear end of the preceding medium P1 has already passed the position where the third sensor 53 can detect when the leading end of the succeeding medium P2 reaches the lower limit of the detection range SA. In addition, the upper limit of the detection range SA is set at a position where a portion having a predetermined length from the leading end can be detected so that the trailing end of the subsequent medium P2 can be detected if the leading end of the subsequent medium P2 is conveyed along a normal path. Is set to

  Here, in the example shown in FIG. 46, the lower limit of the detection range SA is set to a position at which the first sensor 51 detects the leading end of the succeeding medium P2 and switches from OFF to ON. The upper limit of the detection range SA is set to a position (upstream side) before reaching the standby position Yw at which the overlapping operation ends. In the example shown in FIG. 46, the upper limit of the detection range SA is set to the deceleration start position of the overlapping operation.

  When the first sensor 51 that has detected the leading end of the succeeding medium P2 switches from OFF to ON, the control unit 50 starts counting the pulse edges of the detection signal from the encoder 43 by the second counter 82, so that the first The driving amount (counter converted value) of the feed motor 41 from the time when the sensor 51 detects the leading end of the succeeding medium P2 is acquired. Then, the third sensor 53 is enabled only when the leading end position Y2 of the subsequent medium P2 based on the drive amount of the feed motor 41 counted by the second counter 82 is within the detection range SA. That is, the detection process of detecting the succeeding medium P2 that is being overlapped on the normal path is performed only during the period from when the leading end position Y2 of the succeeding medium P2 reaches the lower limit of the detection range SA to when it exceeds the upper limit. Then, the control unit 50 disables the third sensor 53 until the leading end position Y2 of the subsequent medium P2 based on the driving amount of the feeding motor 41 reaches the lower limit of the detection range SA, and does not perform the detection processing. Further, after the leading end position Y2 of the subsequent medium P2 based on the driving amount of the feed motor 41 exceeds the upper limit of the detection range SA, the control unit 50 disables the third sensor 53 and does not perform the detection processing.

  As shown in FIG. 46, if the third sensor 53 is turned on (flag = 1) while the leading end position Y2 of the succeeding medium P2 passes through the detection range SA (flag = 1), the control unit 50 displays a two-dot chain line in FIG. As shown, the overlapping operation is continued until the succeeding medium P2 reaches the standby position Yw. However, if the third sensor 53 does not turn on while the leading end position Y2 of the succeeding medium P2 passes through the detection range SA (flag = 0), the control unit 50 supplies the power at the time when the upper limit of the detection range SA is exceeded. The driving of the feed motor 41 is stopped, and the overlapping operation is interrupted as shown by the solid line in FIG.

Next, with reference to FIG. 47 to FIG. 52, the contents of the conveyance control in the overlapping feeding system will be described. This stack feeding method includes a stacking operation and a stack continuous feeding.
As shown in FIG. 47, when the feeding motor 41 is driven to rotate forward, the preceding medium P1 sent out while being separated into one by the separation plate 157 from the cassette 21 by the rotation of the feeding roller 28 becomes a rotating intermediate medium. After being conveyed along the outer circumference of the roller 30, it is fed toward the conveying roller pair 33. When the first medium P is fed, the overlapping operation is not performed, so that the detection processing by the third sensor 53 is not performed. Thereafter, the leading end of the preceding medium P1 is abutted against the transport roller pair 33 to perform a skew removing operation.

  Next, as shown in FIG. 48, after the skew removing operation, the feed motor 41 and the transport motor 44 are driven synchronously, so that the preceding medium P1 is transported to the printing start position (being caught). . After the cueing, a printing operation of ejecting ink droplets from the print head 38 during one movement of the carriage 36 in the scanning direction X (during one pass) to print one line on the preceding medium P1, Printing is carried out by substantially alternately performing the transport operation of transporting P1 to the next (next row) printing position. As the printing proceeds, the preceding medium P1 is intermittently conveyed to the downstream side in the conveying direction Y. When the feeding roller 28 comes into contact with the subsequent medium P2 in the cassette 21 during the printing, the preceding medium P2 Feeding starts. The succeeding medium P2 sent out from the cassette 21 while being separated into one sheet by the separation plate 157 passes through the outer periphery of the intermediate roller 30 and is fed with a gap from the rear end of the preceding medium P1. Then, when the first sensor 51 detects that the rear end Y1 of the preceding medium P1 has deviated from the nip (first nip position NP1) between the intermediate roller 30 and the second driven roller 32, the driving at that time is performed. The driving speed of the feeding motor 41 is switched from the speed at the time of the transport operation to a higher feeding speed, and the overlapping operation (catch-up feeding operation) of the subsequent medium P2 is started.

  As shown in FIG. 49, due to the overlapping operation, the succeeding medium P2 is sent out tangentially from the nip portion (first nip position NP1) between the intermediate roller 30 and the second driven roller 32, but downstream of the first nip position NP1. Since the guide member 55 located in the vicinity guides the guide surface 56A in a direction (substantially horizontal direction in the drawing), the paper is fed along the guide surface 56A. At this time, as shown in FIG. 42, the subsequent medium P2 is guided in a wavy shape due to the unevenness formed by the pair of concave portions 55D and the projecting portions 55C on the guide surface of the guide member 55.

  As shown in FIG. 44, when the succeeding medium P2 guided by the guide member 55 is fed along a normal path (solid line in FIG. 44) along the guide surface 56A, the third sensor 53 is turned on. On the other hand, when the succeeding medium P2 guided by the guide member 55 is fed along an abnormal path away from the guide surface 56A (two-dot chain line in the figure), the third sensor 53 remains OFF.

  At this time, as shown in FIG. 43, in the process of being guided along the guide surface 56A after hitting the guide surface 56A, the succeeding medium P2 takes a mountain-shaped curved shape, and a part of the medium P2 enters the concave portion 564 and the lever Pressing 53A turns on the third sensor 53. On the other hand, when the medium P2 is fed along an abnormal path (indicated by a two-dot chain line in the drawing) away from the guide surface 56A, the subsequent medium P2 does not enter the recess 564 enough to push the lever 53A against the recess 564. As a result, the third sensor 53 does not turn on.

  Then, as shown in FIG. 50, from the time when the first sensor 51 detects the rear end of the preceding medium P1 (ON → OFF), the feed motor 41 is driven by the target transport amount and stopped, so that the subsequent medium P2 Stops at the position where its tip has reached the standby position Yw. In this state, the leading end of the succeeding medium P2 is overlaid on the trailing end of the preceding medium P1. Thereafter, the succeeding medium P2 that has completed the superimposition operation waits at the standby position Yw until the last pass printing operation for printing the last line on the preceding medium P1 is performed. Then, at a predetermined time before the start of the printing operation of the last pass, if the superimposable condition is satisfied, the feed motor 41 is driven to rotate forward during the printing operation of the last pass, and as shown in FIG. A skew removing operation is performed in which the transport roller pair 33 stops rotating.

  When the printing operation of the last pass is completed, as shown in FIG. 45, the feed motor 41 and the transport motor 44 are driven in synchronization, and the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 have the same transport speed (peripheral speed). ). As a result, as shown in FIGS. 45 and 52, the succeeding medium P2 and the succeeding medium P2 are moved to the printing start position at the same transport speed while maintaining the overlapping amount LP (see FIG. 51) at that time. Overlapping feeding is performed, which is carried together until it reaches (FIG. 52).

  Next, the operation of the printing device 12 will be described. Hereinafter, with reference to FIG. 45, FIGS. 47 to 52, and the like, a description will be given of the transport control including the overlap continuous feeding performed by the computer 62 in the control unit 50 executing the program PR shown in the flowchart of FIG. .

  In step S311, the preceding medium is fed. That is, as shown in FIG. 45, the feeding motor 41 is driven in the normal rotation direction (CW direction) (forward rotation driving), and the preceding medium P1 is fed by the rotation of the feeding roller 28 and the intermediate roller 30, and The skew of the preceding medium P1 is corrected by performing a skew removing operation in which the leading end of the medium P1 is abutted against the transport roller pair 33 whose rotation is stopped. Next, the normal rotation drive of the feed motor 41 and the drive of the transport motor 44 are performed in synchronization, and the preceding medium P1 reaches the print start position by rotating the intermediate roller 30 and the transport roller pair 33 at the same transport speed. It is caught.

  Then, while the carriage motor 48 is driven and the carriage 36 moves in the scanning direction X, the print head 38 ejects ink droplets to print one line (one pass) on the preceding medium P1. Thereafter, the transport operation of transporting the preceding medium P1 to the printing position of the next line and the one-pass printing operation of printing one line are performed substantially alternately, and the printing on the preceding medium P1 is advanced.

  In step S312, it is determined whether the next path is the last path. This determination is made at the timing before the start of the transport operation for transporting the preceding medium P1 to the print position of the next pass for printing the next line. If it is not the last pass, the process proceeds to step S313, and if it is the last pass, the process proceeds to step S326.

  In step S313, it is determined whether or not the overlapping operation has been performed. The computer 62 has a flag in the storage unit that sets “0” before the superposition operation is performed and “1” when the superposition operation is performed. It is determined that there is, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has not been performed, the process proceeds to step S314. If the overlapping operation has been performed, the process proceeds to step S323.

  In step S314, it is determined whether the first sensor has been switched from ON to OFF. That is, it is determined whether or not the rear end of the preceding medium P1 has passed the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 switches from ON to OFF, the process proceeds to step S315, and if it does not switch from ON to OFF, the process proceeds to step S323. When the first sensor 51 switches from ON to OFF, the computer 62 causes the first counter 81 to perform a counting process, and obtains the rear end position Y1 of the preceding medium P1 from the counted value.

  In step S315, it is determined whether or not overlapping is possible. In other words, it is determined whether or not a superimposable condition, which is a precondition for performing continuous superimposition, is satisfied. Whether the overlap condition including the margin condition including that the trailing end position Y1 of the preceding medium P1 is within the overlap region LA (LL ≦ Y1 <LU) and the print density condition where the print duty is equal to or less than the threshold are satisfied. Determine whether or not. If the superimposable condition is satisfied, the process proceeds to step S316. If the superimposable condition is not satisfied, the process proceeds to step S323.

  In step S316, the overlapping operation is started. Specifically, when the first sensor 51 switches from ON to OFF (YES in S314), the computer 62 drives the feed motor 41 in the normal rotation direction, and rotates the feed roller 28 and the intermediate roller 30 to rotate the feed roller 28 and the intermediate roller 30. The succeeding medium P2 is fed to the standby position Yw. In this feeding process, when the first sensor 51 detects the leading end of the succeeding medium P2 and switches from OFF to ON, the computer 62 counts a value representing the driving amount of the feeding motor 41 in the second counter 82. The counting process is started, and the leading end position Y2 of the succeeding medium P2 corresponding to the driving amount of the feeding motor 41 is acquired from the counted value. In this overlapping operation, the succeeding medium P2 is transported at a transport speed higher than the transport speed of the preceding medium P1 during printing, and the forward rotation drive of the feed motor 41 is performed until the leading end position Y2 reaches the standby position Yw. continue.

  In step S317, it is determined whether the subsequent medium has reached the standby position. If the subsequent medium has not reached the standby position Yw, the process proceeds to step S318, and if it has reached the standby position Yw, the process proceeds to step S323.

  In step S318, it is determined whether the third sensor has been detected. If the third sensor 53 has not been detected, the process proceeds to step S319. If the third sensor 53 has been detected, the process returns to step S317.

  In step S319, it is determined whether the succeeding medium has exceeded the lower limit of the detection range. Specifically, the computer 62 of the control unit 50 determines whether the leading end position Y2 of the succeeding medium P2 based on the driving amount of the feed motor 41 represented by the count value counted by the second counter 82 has exceeded the lower limit of the detection range SA. Judge. If the succeeding medium P2 does not exceed the lower limit of the detection range SA, the process returns to step S317, and if the subsequent medium P2 exceeds the lower limit of the detection range SA, the process proceeds to step S320. If the leading end position Y2 of the succeeding medium P2 does not exceed the lower limit of the detection range SA, the third sensor 53 is invalid and the detection process is not performed. If the leading end position Y2 of the succeeding medium P2 is below the lower limit of the detection range SA, the third sensor 53 is enabled and the detection process is performed.

  In step S320, it is determined whether the third sensor has detected. If the third sensor 53 detects, the process returns to step S317, and if the third sensor does not detect, the process proceeds to step S321. The succeeding medium P2 during the superimposing operation is guided by the guide member 55 and takes a mountain-shaped curved shape (solid line in FIG. 43). When conveyed along a normal path, a part of the curved part enters the concave portion 564. To turn on the third sensor 53. When the third sensor 53 is turned on, the computer 62 sets the flag to “1”. On the other hand, when the succeeding medium P2 during the overlapping operation is transported along an abnormal path away from the guide surface 56A, the third sensor 53 does not turn on. In this case, the flag remains “0”.

  In step S321, it is determined whether or not the succeeding medium has exceeded the upper limit of the detection range. Specifically, the computer 62 of the control unit 50 determines whether the leading end position Y2 of the succeeding medium P2 based on the driving amount of the feeding motor 41 represented by the count value counted by the second counter 82 has exceeded the upper limit of the detection range SA. Judge. If the succeeding medium does not exceed the upper limit of the detection range, the process returns to step S317, and if the subsequent medium exceeds the upper limit of the detection range, the process proceeds to step S322.

  In step S322, the overlapping operation is stopped. That is, when the third sensor 53 does not detect (ON) in the section where the leading end position Y2 of the succeeding medium P2 is within the detection range SA (No in S320), the succeeding medium P2 in the overlapping operation is on a normal path. Since the sheet has not been conveyed, the drive of the feed motor 41 is stopped at the time when the upper limit of the detection range SA is exceeded (Yes in S321), and the overlapping operation is stopped.

  In step S323, the transport operation is performed to the printing position of the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. For example, when the next line is the first line, the preceding medium P1 is located at the print start position (see FIG. 7).

  In step S324, a printing operation for one pass is performed. The computer 62 drives the carriage motor 48 to move the carriage 36 by one pass in the scanning direction X, and causes the print head 38 to eject ink droplets from the nozzles 382 based on print data during the one pass movement. Then, a printing operation for printing an image for one pass on the preceding medium P1 is performed.

  In step S325, it is determined whether printing of one page has been completed. That is, it is determined whether the printing operation of all the lines of the preceding medium P1 has been completed. If printing of one page has not been completed, the process returns to step S312, and if printing of one page has been completed, the process proceeds to step S332.

  When returning to step S312, thereafter, the processing of steps S312 to S325 is repeated until the last pass is reached in step S312. At this time, if the overlapping operation has been performed (flag = “1”), the transport operation to the next line (S323) and the printing operation for one pass to the next line (S324) are substantially alternately performed. By doing so, printing on the preceding medium P1 is advanced. On the other hand, if the overlapping operation has not been performed (flag = “0”), the first sensor 51 is switched from ON to OFF (an affirmative determination in S314) before the last pass (NO in S312), and overlapping is possible. When the condition is satisfied (Yes in S315), the overlapping operation is performed (S316). If the first sensor 51 detects the rear end of the preceding medium P1 before reaching the last pass, and the superimposable condition is satisfied at that time, the superimposing operation is started (S316).

  Then, when the printing operation of the pass immediately before the last pass is completed, the process returns to step S312, and it is determined whether the next pass is the last pass. This determination is made during the period from the end of the printing operation of the pass (n-1st pass) immediately before the last pass (n-th pass) to the start of the transport operation of the preceding medium P1 to the printing position of the last pass. When the next pass is the last pass, the process proceeds to step S326.

  In step S326, it is determined whether or not the overlapping operation has been performed. The computer 62 determines whether or not the overlapping operation has been performed based on the value of the flag. That is, if the value of the flag is “1”, it is determined that the overlapping operation has been performed, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has been performed, the process proceeds to step S327. If the overlapping operation has not been performed (if the overlapping operation has not been performed), the process proceeds to step S323.

  If the stacking operation has not been performed, since the continuous stacking cannot be performed, the transport operation (S323) is performed to the next line (the printing position of the last pass), and the printing operation of one line (one line of the last pass) is performed. (S324) is performed. When printing of the last pass is completed and printing of one page of the preceding medium P1 is completed (YES in S325), in step S332, a discharging operation of discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. When printing of the preceding medium P1 is completed in this way and one routine is completed, the succeeding medium P2 up to that time becomes the preceding medium P1, and the third page becomes a new succeeding medium P2. Then, the computer 62 executes again the print control routine shown in FIG. 53 for printing the next page, and performs the feeding operation of the succeeding medium P2 as a new preceding medium P1 in step S311. At this time, since the preceding medium P1 of the first page has already been discharged, the discharging of the preceding medium P1 and the feeding of the succeeding medium P2 are performed with an interval therebetween. On the other hand, if the next pass is the last pass (Yes in S312) and the overlapping operation has been performed (Yes in Step S326), the process proceeds to Step S327, and the following processing is performed.

  In step S327, the transport operation is performed up to the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line.

  In step S328, a printing operation for one pass is performed. That is, the computer 62 drives the carriage motor 48 to cause the carriage 36 to move in the last path, and in the course of the movement, ejects ink droplets from the nozzles 382 of the print head 38 to print the last line.

  In the step S329, it is determined whether or not the continuous feeding is possible. Here, it is determined whether or not the succeeding medium P2 that has completed the stacking operation is in a stacking ready state waiting at the standby position Yw. If it is possible to continuously feed the document, the process proceeds to step S330. If not, the process proceeds to step S332. It should be noted that, in addition to being in a state of completion of stacking preparation, from the actual positions of the media P1 and P2 based on the current position information of the media P1 and P, for example, the rear end position Y1 of the preceding medium P1 is LL ≦ Y1 <LU. For example, it may be determined whether or not at least one condition for confirming that the position of the medium is at a position at which the continuous feeding can be performed, such as determining whether or not the position is a position that satisfies the above condition.

In step S330, a skew removing operation is performed. More specifically, when the drive of the transport motor 44 is stopped to end the transport operation for transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the carriage motor 48 to perform the printing operation. The skew for correcting the skew of the succeeding medium P2 by driving the feeding motor 41 while the driving of the conveying motor 44 is stopped in this printing operation and abutting the leading end of the succeeding medium P2 against the conveying roller pair 33 that is not rotating. Perform the picking operation.
When the drive of the transport motor 44 is stopped to end the transport operation of transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the feed motor 41 and starts transporting the subsequent medium P2 from the standby position Yw. A skew removing operation is performed in which the leading end of the lever abuts against the pair of transport rollers 33 whose rotation is stopped.

  Then, in the next step S331, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the conveying motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are The continuous feeding (hatched portion in FIG. 45) in which the sheets are transported at the same transport speed while maintaining the overlapping amount is performed. As a result, the succeeding medium P2 is moved to the printing start position while maintaining the overlapping amount with the preceding medium P1. As shown in FIG. 45, when the printing of the last line of the first sheet is completed, the first sheet P1 and the second sheet P2 are placed on at least a part of the trailing margin of the preceding sheet P1. P2 is conveyed together while maintaining the overlapping state, and the second medium P2 is moved to the print start position. In the case of this overlapping feeding system, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the transport amount when the cueing of the succeeding medium P2 to the printing start position is limited to the preceding medium P1. Is relatively small as compared with the transport amount in the normal feeding method in which the succeeding medium P2 is caught at an interval. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, in step S332, the preceding medium is ejected. At this time, the succeeding medium P2 is at the standby position Yw when the overlapping operation is performed, and is located upstream of the standby position Yw when the overlapping operation is not performed. Therefore, even if the transport motor 44 is driven to rotate the transport roller pair 33 and the discharge roller pair 34, only the preceding medium P1 is discharged, and the subsequent medium P2 waits at the position at that time.

  If there is a next page, after the discharging operation is completed, the feeding operation of the medium P for the next page is performed in step S311. However, since the next medium (previous succeeding medium P2) is stopped at the standby position Yw or a position slightly upstream from the standby position Yw, the feeding operation of the preceding medium P1 (previous succeeding medium P2) is performed. As a result, a new (second page) preceding medium P1 is located at the print start position. If the rear end position Y1 is at a position that has passed the second nip position NP2 by a predetermined distance or more during the printing operation of the last pass, the skew removing operation of the succeeding medium P2 is performed during the printing operation of the last pass, and After the end of the printing operation, the ejection of the preceding medium P1 and the cueing of the succeeding medium P2 may be performed with an interval therebetween. During the ejection of the preceding medium P1, the computer 62 starts driving the feed motor 41 at a timing when the rear end of the preceding medium P1 passes the transport roller pair 33 and a certain interval is secured, and the skew is removed. May be started to transport the subsequent medium P2 to the printing start position. Further, when the printing of the last pass is started during the stacking operation, the stacking operation and the skew removing operation may be performed together by directly abutting the leading end of the succeeding medium P2 to the transport roller pair 33 that is not rotating. Good.

According to the fourth embodiment described in detail above, the following effects can be obtained.
(4-1) At a position between the intermediate roller 30 as an example of the first roller and the transport roller pair 33 as an example of the second roller, it is possible to detect the succeeding medium P2 being transported along the normal path of the overlapping operation, and A third sensor 53 is provided as an example of a sensor that cannot detect the succeeding medium P2 being transported on a route other than the normal route. If the succeeding medium P2 being conveyed along a normal path is detected during the stacking operation according to the detection result of the third sensor 53, the stacking operation is performed after the stacking operation is completed. On the other hand, when the third sensor 53 cannot detect the succeeding medium P2 because the sheet is not conveyed on the normal path during the overlapping operation, the overlapping continuous feeding is not performed after the completion of the overlapping operation. Therefore, since the succeeding medium P2 takes an inappropriate conveyance path during the overlapping operation, the overlapping order of the preceding medium P1 and the succeeding medium P2 is reversed up and down, or the rear end of the preceding medium P1 and the leading end of the succeeding medium P2 are The print quality can be prevented from deteriorating due to the continuous feeding with the stacking errors such as collisions.

  (4-2) The control unit 50 constitutes a transport unit from when the first sensor 51 detects that the leading end of the succeeding medium P2 has deviated from the nip position NP1 of the intermediate roller 30 as an example of a first sensor. The leading end position Y2 of the succeeding medium P2 based on the driving amount of the feed motor 41 is acquired. The control unit 50 does not perform the detection process of detecting the succeeding medium P2 being overlapped on a normal path by the third sensor 53 until the leading end position Y2 of the succeeding medium P2 reaches the lower limit of the detection range SA. If the lower limit of SA is exceeded, a detection process is performed. Therefore, it is possible to prevent erroneous detection that the third sensor 53 has detected the flutter of the rear end portion of the preceding medium P1 as having detected the succeeding medium P2 conveyed along a normal path.

  (4-3) The control unit 50 determines that the tip position Y2 of the subsequent medium P2 based on the driving amount of the feed motor 41 from when the first sensor 51 detects the tip of the subsequent medium P2 is detected by the third sensor 53. The detection process for detecting the succeeding medium P2 is performed until the upper limit of the range SA is reached, and when the upper limit is exceeded, the detection process is stopped. Therefore, it is possible to prevent erroneous detection that the third sensor 53 has detected the fluttering of the leading end of the succeeding medium P2 by detecting the succeeding medium P2 conveyed along the normal path during the overlapping operation.

  (4-4) The control unit 50 detects the tip position Y2 of the succeeding medium P2 based on the driving amount of the feed motor 41 from when the first sensor 51 detects the leading edge of the succeeding medium P2. If it is within the range SA, the detection process of the subsequent medium P2 is performed, and if it is not within the detection range SA, the detection process of the subsequent medium P2 by the third sensor 53 is stopped. Therefore, even though the succeeding medium P2 is not conveyed along the normal path, the detection of the fluttering of the trailing end of the preceding medium P1 and the fluttering of a portion other than the leading end of the succeeding medium P2 are detected by the overlapping operation. It is easy to avoid erroneous detection that the succeeding medium conveyed along the normal route is detected.

  (4-5) The printing device 12 includes a guide surface 56A that can guide the succeeding medium P2 along a normal path when the overlapping operation of the subsequent medium P2 is performed between the intermediate roller 30 and the transport roller pair 33; And a guide member 55 disposed at a position downstream of the first nip position NP1 in the transport direction Y to guide the succeeding medium P2 in a direction intersecting the guide surface 56A. The trailing medium P2 whose tip has passed the nip position NP1 of the intermediate roller 30 is disposed at a position downstream of the nip position NP1 in the transport direction Y, and the guiding member 55 causes the trailing medium P2 to intersect with the guide surface 56A. After being guided and reaching the guide surface 56A, it is conveyed along a normal route along the guide surface 56A. By being transported along the guide surface 56A, the succeeding medium P2 can be overlaid on the preceding medium P1 in a normal overlapping order. Then, if the sheet is not conveyed along a normal route after coming off the guide surface 56A, it is not detected by the third sensor 53. For this reason, when there is a possibility that the succeeding medium P2 is not correctly superimposed on the preceding medium P1 in the superimposing operation without being conveyed along the guide surface 56A, the continuous superimposition can be stopped. As a result, it is possible to avoid a printing error or a medium jam that occurs when continuous feeding is performed with a stacking error in which the stacking operation has failed.

  (4-6) The guide member 55 is configured to guide the succeeding medium P2 in a state of being convexly curved toward the guide surface 56A. The guide surface 56 </ b> A is provided with a concave portion 564 into which a part of the convexly curved portion of the subsequent medium P <b> 2 can enter. Detect the part that did. If the succeeding medium P2 is normally conveyed, the portion curved in the width direction of the subsequent medium P2 into the concave portion 564 of the guide surface 56A is detected by the third sensor 53. Therefore, if the succeeding medium P2 is not properly guided by the guide member 55 and does not curve in a convex shape, or is not conveyed along the guide surface, it is not detected by the third sensor 53. Therefore, the succeeding medium P2 conveyed along the normal path can be detected by distinguishing the succeeding medium P2 conveyed along the normal path from the succeeding medium P2 not along the normal path.

  (4-7) The guide member 55 includes a pair of recesses 55D arranged in the width direction X intersecting with the transport direction Y of the subsequent medium P2, and a protrusion 55C as an example of a protrusion disposed between the pair of recesses 55D. And Therefore, when the succeeding medium P2 is guided by the guide member 55 and hits the protrusion 55C disposed between the pair of recesses 55D, the subsequent medium P2 can be curved in a convex shape in the width direction X.

(2 of the fourth embodiment)
Next, 2 of the fourth embodiment will be described with reference to FIGS. 54A, 54B, and 55. FIG. As shown in FIG. 54A, the printing apparatus 12 of the present embodiment performs lower stacking in which the front end of the succeeding medium P2 is stacked from below the rear end of the preceding medium P1. The printing device 12 is guided obliquely downward by the guide member 55, which is disposed at a position immediately downstream of the nip portion of the upstream conveying roller pair 301 in a posture inclined obliquely downward for lower stacking. And a lower guide surface 571 that forms a lower path for a lower stack that supports the succeeding medium P2. The lower guide surface 571 has a concave first guide surface portion 571 </ b> A that forms a lower path for lower stacking located closer to the upstream side in the transport direction Y, and a rear end of the preceding medium P <b> 1 to a nip portion of the transport roller pair 33. It has a second guide surface portion 571B that supports the portion to be guided substantially horizontally, and a slope 571C that connects the first guide surface portion 571A and the second guide surface portion 571B. The bottom surface of the concave first guide surface portion 571A is located lower than the second guide surface portion 571B. The first guide surface portion 571A is capable of detecting the succeeding medium P2 being transported along a normal path along the first guide surface portion 571A during the overlapping operation, and being capable of detecting the succeeding medium P2 being transported along an abnormal path away from the first guide surface portion 571A. A third sensor 531 for normal detection is provided as an example of a second sensor that cannot detect P2. The lever 531A of the third sensor 531 slightly protrudes from the first guide surface portion 571A, and the subsequent medium P2 that is being conveyed along a normal path along the lower guide surface 571 during the overlapping operation pushes the lever 531A to move the third medium P3 to the third position. The sensor 531 can be turned on.

  In the same manner as described in 1 of the fourth embodiment, it is also possible to use the guide member 55 that can guide a downwardly convex curved shape in the process of guiding the succeeding medium P2. In this case, the first guide surface portion 571A is provided with a concave portion into which a part of the convexly curved portion below the subsequent medium P2 enters, and the third sensor 531 enters the concave portion of the downwardly convexly curved subsequent medium P2. What is necessary is just to comprise so that a part may be detectable with the lever 531A.

  An upper guide surface 566 is provided at a position higher than the nip portion of the transport roller pair 33 at an upper position facing the guide surface 571. The upper guide surface 566 functions as a regulating surface that regulates the succeeding medium P2 conveyed along an abnormal path during the stacking operation. A downstream medium that is conveyed along an abnormal path during the stacking operation and that enters the upper side of the rear end of the preceding medium P1 and is regulated by the upper guide surface 566 is located at a position downstream of the upper guide surface 566 in the conveyance direction Y. A third sensor 532 for abnormality detection capable of detecting P2 is provided. The third sensor 532 includes a lever 532A that slightly projects from the upper guide surface 566.

  As shown in FIG. 54A, during the overlapping operation, the subsequent medium P2 is guided obliquely downward by the guide member 55 located immediately downstream in the process of being sent out by the rotation of the pair of transport rollers 301 on the upstream side, and the lower guide surface 571 is provided. You will be guided along. When the succeeding medium P2 is conveyed along a normal path along the first guide surface portion 571A of the lower guide surface 571, the succeeding medium P2 is detected by the third sensor 531. When the overlapping operation is performed on the normal path in this way, as shown in FIG. 54B, the leading end of the succeeding medium P2 fed to the standby position shown in FIG. 54 by the overlapping operation is placed on the second guide surface portion 571B. It overlaps with the rear end of the supported preceding medium P1 from below. Thereafter, at a predetermined overlapping continuous feeding start time, if the third sensor 531 is ON during the overlapping operation, the overlapping continuous feeding is performed. The predetermined overlapping continuous feed start timing is defined as the time of the first transport operation after the length of the portion of the preceding medium P1 upstream of the nip position of the transport roller pair 33 becomes less than the leading edge margin length of the subsequent medium P2. This is the start timing. However, as long as the previous printing operation is not the last pass, the succeeding medium P2 is also conveyed while maintaining the overlap amount during the conveying operation of the preceding medium P1, and when the last pass is completed, the preceding medium P1 and the succeeding medium P2 Is continuously conveyed together while maintaining the overlap amount.

  On the other hand, as shown in FIG. 55, for example, when the trailing end of the preceding medium P1 is curled downward and the leading end of the succeeding medium P2 is curled upward, the leading end of the succeeding medium P2 is The medium P2 is lifted above the rear end of the preceding medium P1, and the subsequent medium P2 is transported along an abnormal path (that is, an abnormal path). In this case, the third sensor 531 for normal detection is not turned on, and the tip of the succeeding medium P2 regulated by hitting the upper guide surface 566 pushes the lever of the third sensor 532 for abnormality detection, so that the third sensor 531 is turned off. 532 turns ON. As described above, when the third sensor 531 is OFF and the third sensor 532 is ON, the overlapping continuous feeding is not performed even when a predetermined overlapping continuous feeding start time comes. Therefore, it is possible to reduce the frequency of occurrence of a printing error or a medium jam due to the continuous feeding even though the stacking operation has failed.

Therefore, in the second embodiment of the fourth embodiment, the same kind of effects as the above (4-1) to (4-7) can be obtained only by the overlapping order of the preceding medium P1 and the succeeding medium P2. Can be.
The fourth embodiment can be changed to the following modes.

  In 1 and 2 of the fourth embodiment, as the feeding mechanism 26, a pair of guide members 555 capable of selecting an upper layer and a lower layer as shown in FIGS. , 556 may be employed. In this case, as shown in FIG. 79, a third sensor 533 capable of detecting the subsequent medium P2 conveyed along the normal conveyance path along the guide surface 56A forming the upper path when the upper stack is selected, As shown at 80, a third sensor capable of detecting the succeeding medium P2 conveyed along a normal conveyance path along the guide surface 57A (particularly, the second support surface 578) that forms the lower path when the lower stack is selected. 534 may be provided. Further, a guide surface portion shown in FIG. 42 capable of guiding the succeeding medium P2 in a curved state that is convex upward toward the guide surface 56A is formed on the guide member 556 for upper lap, and the guide member 555 for lower lap is formed with: A guide surface portion as shown in FIG. 42 capable of guiding the succeeding medium P2 in a curved state convex downward toward the guide surface 57A is formed. Then, a concave portion 564 shown in FIG. 43 concaved upward in the guide surface 56A is formed, and a concave portion inverted vertically in the concave portion 564 shown in FIG. 43 concaved downward in the guide surface 57A is formed. According to this configuration, it is possible to detect whether or not the overlapping operation is performed on a normal path along the guide surface 56A when the upper layer is selected. If the route is not normal, the continuous feeding is stopped. On the other hand, when the lower stacking is selected, it is possible to detect whether or not the stacking operation is performed on the normal path along the guide surface 57A. If not, the continuous feeding is stopped. Therefore, it is possible to reduce the frequency of printing errors caused by performing continuous feeding while the stacking operation has failed. In the examples of FIGS. 79 and 80, the transport roller pair 93 corresponds to an example of a first roller, and the transport roller pair 33 corresponds to an example of a second roller.

  In 1 and 2 of the fourth embodiment, the guide surface of the guide member 55 is formed such that one convex portion of the mountain shape is provided at a position corresponding to the central portion in the width direction X, that is, the central portion of the medium P in the width direction X. The shape provided may be sufficient.

  The concave portion 564 in the guide surface 56A of the ceiling wall portion 56 may be eliminated, and the guide surface 56A may be a slope. In this case, the lever 53A of the third sensor 53 is made to protrude from the slope of the guide surface 56A so that the succeeding medium P2 conveyed along a normal path along the guide surface 56A formed of the slope can be detected and the normal medium P2 separated from the guide surface 56A can be detected. The third sensor 53 may be configured to be unable to detect the succeeding medium P2 conveyed by a different route.

<Fifth embodiment>
The fifth embodiment is an example showing a configuration and control for improving the stop position accuracy with respect to a standby position Yw, which is a target position for stopping the succeeding medium in the overlapping operation. Hereinafter, 1 and 2 of the fifth embodiment will be sequentially described with reference to the drawings.

(1 of the fifth embodiment)
First, one of the fifth embodiments will be described with reference to FIGS. 7, 45, 56, and 57. FIG. The basic configuration and the electrical configuration of the MFP 11 and the printing device 12 are the same as those of the first and fourth embodiments. That is, the basic configuration and the electrical configuration of the printing apparatus 12 are the same as those in FIGS. 1 to 7 of the first embodiment. The program PR stored in the non-volatile memory 75 shown in FIG. 7 includes the program shown in the flowchart in FIG.

  As shown in FIG. 56, a first sensor 51 and a second sensor 52 capable of detecting the presence or absence of the medium P are provided at predetermined positions on the transport path between the intermediate roller 30 and the transport roller pair 33 in the transport direction Y. They are arranged in this order from the upstream side in the transport direction Y. The controller 50 uses the detection signals of the sensors 51 and 52 for controlling the transport of the medium P. The first sensor 51 can detect the presence or absence of the medium P at a position near the downstream side in the transport direction Y at the nip between the intermediate roller 30 and the second driven roller 32. The first sensor 51 of the present example is a contact sensor and has a lever 51A that can contact the medium P. When the lever 51A is at the position shown by the two-dot chain line in FIG. 56, the first sensor 51 does not detect the medium P, and is pushed by the medium P and is arranged at the position shown by the solid line in FIG. Detect and output detection signal. The first sensor 51 is turned off, for example, at the time of non-detection, and turned on at the time of detection.

  Further, the second sensor 52 can detect the presence or absence of the medium P with a position slightly upstream in the transport direction Y from the nip portion of the transport roller pair 33 as a detection target position. When the lever 52A is at the position shown by the two-dot chain line in FIG. 56, the second sensor 52, which is a contact sensor, is not detected by the medium P and is pushed by the medium P and is arranged at the position shown by the solid line in FIG. As a result, the medium P is detected, and a detection signal is output. The second sensor 52 is turned off, for example, at the time of non-detection, and turned on at the time of detection. Note that the standby position Yw is set between the detection position of the second sensor 52 and the nip position NP2 of the transport roller pair 33 in the transport direction Y. Note that the first sensor 51 and the second sensor 52 may be optical sensors instead of contact sensors.

  In the overlapping operation process, since the lever 52A of the second sensor 52 is in the ON state where the rear end of the preceding medium P1 has been detected, the leading end of the succeeding medium P2 cannot be detected. For this reason, the second sensor 52 cannot detect the leading end of the succeeding medium P2 at a position overlapping with the preceding medium P1 in the overlapping operation process regardless of whether it is a contact type or an optical type. In the normal feeding method, when the medium P is located at the print start position, a position where the second sensor 52 detects the leading end of the medium P is used as a reference, and a predetermined number of pulses (the number of steps) is counted from the reference position. After that, the position of the medium P is stopped at the target position by stopping the driving of the feeding motor 41. For this reason, in the case of the normal feeding method, if the target position is located downstream of the detection target position of the second sensor 52 in the transport direction Y, the distance upstream from the target position and the distance from the target position is smaller. It is preferable to control the stop position of the medium P using the short second sensor 52.

  However, in the case of the overlap feeding method, since the second sensor 52 detects the rear end of the preceding medium P1 and is kept in the ON state, the second sensor 52 cannot detect the front end of the succeeding medium P2. For this reason, stop position control for stopping the leading end of the succeeding medium P2 at the standby position Yw using the second sensor 52 cannot be performed. For this reason, in the present embodiment, the leading end of the succeeding medium P2 is placed in the standby position by using the first sensor 51 which is disposed upstream of the second sensor 52 in the transport direction Y and is used to determine the start timing of the overlapping operation. Stop position control for stopping at Yw is performed. That is, based on the position at which the first sensor 51 detects the leading end of the succeeding medium P2, by stopping after counting a predetermined number of pulses (the number of steps) from the reference position, the succeeding medium P2 is moved to the standby position Yw Stop position control is performed to stop the motor. However, the distance between the standby position Yw, which is the target position, and the detection position of the first sensor 51 is about twice as long as the distance between the standby position Yw and the detection position of the second sensor 52. Therefore, in the stop position control using the first sensor 51, errors are more likely to accumulate due to the longer distance (target step number) for counting the number of pulses (number of steps), and the stop position accuracy in the stop position control is reduced. I do.

  If the accuracy of the stop position at which the succeeding medium P2 stops at the standby position Yw is low, the overlapping condition must be set narrower in consideration of the error of the stop position accuracy. In this case, despite the fact that the continuous overlapping transmission could be actually performed, the narrowly set overlapping enabled condition cannot be satisfied, which causes a situation in which the frequency of the continuous overlapping transmission is reduced. For this reason, the present embodiment employs a configuration in which even when the first sensor 51 is used, the stop position accuracy of the succeeding medium P2 with respect to the standby position Yw is improved.

  The computer 62 of the control unit 50 shown in FIG. 7 executes the program PR shown in the flowchart of FIG. 57 stored in the non-volatile memory 75 to stop the subsequent medium P2 at the standby position Yw with high positional accuracy. Is performed. Further, the non-volatile memory 75 shown in FIG. 7 stores a transport distance FD to be referred to when performing an overlapping operation described later and data used when calculating the transport distance FD. For example, as one of the data, the third drive amount data corresponding to the distance ND (see FIG. 56) from the detection position of the second sensor 52 to the nip position NP2 of the transport roller pair 33 is stored in the nonvolatile memory 75. I have. The distance ND is a value corresponding to the counter, and is a value indicating the driving amount of the feeding motor 41 required to transport the medium P by the distance ND. In the present embodiment, the nonvolatile memory 75 corresponds to an example of a storage unit, and the distance ND corresponds to an example of a third driving amount.

  When the computer 62 receives the print data PD (print job data) including the printing conditions of plain paper, band printing, and single-sided printing, the computer 62 selects the overlapping feeding method as the feeding method, and selects other printing conditions. Select the normal feeding method. When the overlap feeding method is selected, the computer 62 executes the print control program PR shown in FIG.

  Further, the controller 50 shown in FIG. 7 causes the second counter 82 to detect the first encoder 43 from the point in time when the first sensor 51 switches from OFF to ON and detects the leading end of the preceding medium P1 or the succeeding medium P2. A counting process for counting the number of pulse edges of the signal is performed, and the leading end position Y2 (= Lo−Lc2) of the succeeding medium P2 is obtained from the count value Lc2. Even when the overlap feeding method is selected, when the first medium P is fed, the leading end of the medium P can be detected by the second sensor 52. In the course of feeding the first medium P, the control unit 50 moves the second sensor 82 from the detection position S1 of the first sensor 51 based on the count value counted by the second counter 82 as shown in FIG. The distance SD to the detection position S2 of the second sensor 52, that is, the first drive amount indicated by a counter equivalent value of the distance SD between the detection positions S1 and S2 of the two sensors 51 and 52 is measured. The control unit 50 temporarily stores in the nonvolatile memory 75 the distances SD measured a plurality of times during the feeding process of different media P. The transport distance FD shown in FIG. 56 is calculated using the average distance SDave which is the average of the distances SD for a plurality of times, and the second drive amount indicated by the counter value of the transport distance FD is stored in the nonvolatile memory 75.

  When the trailing end of the preceding medium P1 deviates from the first nip position NP1 and the first sensor 51 switches from ON to OFF, the control unit 50 changes the driving speed of the feeding motor 41 from the transport driving speed to a higher speed. Switching to the drive speed starts the superimposition operation of transporting the succeeding medium P2 at a feed speed higher than the transport speed of the preceding medium P1. When the leading end of the succeeding medium P2 is detected by the first sensor 51 during the overlapping operation and is switched from OFF to ON, the control unit 50 causes the second counter 82 to start a counting process, and the count value is determined as the transport distance. When the second drive amount indicated by the FD counter value is reached, the driving of the feed motor 41 is stopped in order to stop the overlapping operation.

  Next, with reference to FIG. 56, conveyance control for improving the stop position accuracy of the overlapping operation will be described. As shown in FIG. 56, the switching position of the first sensor 51 between OFF and ON is defined as a detection position S1, and the switching position of the second sensor 52 between OFF and ON is defined as a detection position S2. The first detection position S1 is located slightly downstream of the first nip position NP1 in the transport direction Y. In the present embodiment, in the process of feeding the first medium P, the transport distance FD from the detection position S1 of the first sensor 51 to the standby position Yw is measured, and the measured transport distance FD is stored in the nonvolatile memory 75. Remember. The superimposing operation of the succeeding medium P2 is performed with reference to the measured transport distance FD.

  Hereinafter, a method of measuring the transport distance FD will be described. In the process of feeding the first medium P, the computer 62 determines the distance SD between the sensors from the detection position S1 of the first sensor 51 to the detection position S2 of the second sensor 52 by a counting process of the first counter 81. Measured by 56, the distance ND from the detection position S2 of the second sensor 52 to the nip position NP2 of the transport roller pair 33 and the distance from the nip position NP2 of the transport roller pair 33 to the standby position Yw. Is stored beforehand. Then, the computer 62 uses the measured distance SD between the sensors and the distance ND and the distance yn read from the nonvolatile memory 75 to the transport distance FD (from the detection position S1 of the first sensor 51 to the standby position Yw). = SD + ND-yn) and stores it in the non-volatile memory 75 to set the transport distance FD.

  Note that the distance ND stored in the nonvolatile memory 75 in advance is measured, for example, in a pre-shipment inspection of the MFP 11. The printing apparatus 12 in the multifunction peripheral 11 feeds a medium P (measurement sheet) having a predetermined thickness and a predetermined size from the cassette 21 to a printing start position. At this time, the computer 62 causes the first counter 81 to start the counting process from the detection position S2 at which the second sensor 52 has detected the leading end of the measurement sheet. The driving of the feeding motor 41 is stopped. The computer 62 subtracts the distance between the leading end of the measurement sheet and the position of the most upstream nozzle #Q from the target value to obtain the distance QD between the detection position S2 and the most upstream nozzle #Q. Further, the computer 62 subtracts a known distance RD between the position of the most upstream nozzle #Q and the second nip position NP2 from the distance QD, and stores a value corresponding to the counter count value of the distance ND in the nonvolatile memory. 75.

  Next, the operation of the printing device 12 will be described. Hereinafter, with reference to FIGS. 45, 47 to 52, and the like, a description will be given of the transport control including the overlapping continuous feeding performed by the computer 62 in the control unit 50 executing the program PR shown in the flowchart of FIG.

  In step S411, the first medium is fed. That is, as shown in FIG. 45, the feeding motor 41 is driven in the normal rotation direction (CW direction) (forward rotation driving), and the first medium P is fed by the rotation of the feeding roller 28 and the intermediate roller 30. I do. That is, when the feeding roller 28 rotates, the uppermost medium P in the cassette 22 is sent out, and slides on the surface of the separation plate 157 to be separated into one sheet. The separated first medium P is fed while being nipped at two places by two driven rollers 31 and 32 along a path along the outer circumference of the intermediate roller 30.

  In step S412, the distance SD between the sensors is measured. When the leading end of the first medium P passes through the nip position NP1 between the intermediate roller 30 and the second driven roller 32, and the first sensor 51 detecting the leading end of the medium P switches from OFF to ON, the computer 62 Causes the first counter 81 to start the counting process. That is, when the first sensor 51 switches from OFF to ON, the computer 62 causes the first counter 81 to start counting processing for counting the number of pulse edges of the detection signal input from the first encoder 43. Then, the leading edge of the first medium P being fed is detected by the second sensor 52. When the second sensor 52 that has detected the leading end of the first medium P switches from OFF to ON, the counting process of the first counter 81 is stopped, and the count value of the first counter 81 is obtained. This count value corresponds to the distance SD from the detection position S1 of the first sensor 51 to the detection position S2 of the second sensor 52. That is, in this measurement process, the distance SD between the sensors 51 and 52 is obtained as a value equivalent to the counter count value.

  In step S413, the average distance SDave is calculated. In the present embodiment, the data of the distance SD between the sensors measured in the past is stored in, for example, the nonvolatile memory 75, and the computer 62 calculates the distance SD measured this time and the nearest K−1 data read from the nonvolatile memory 75. Then, an average distance SDave is calculated by dividing the sum of K (where K is a natural number) distances SD including the distance SD.

  In step S414, the transport distance FD is calculated. That is, the computer 62 calculates the transport distance FD using the average distance SDave and the formula FD = SDave + ND-yn. The transport distance FD is a distance from the detection position S1 of the first sensor 51 to the standby position Yw. Here, the value ND is a distance (for example, a value corresponding to a counter count value) from the detection position S2 of the second sensor 52 to the nip position NP2 of the transport roller pair 33, and is measured in advance and stored in the nonvolatile memory 75. Value. The computer 62 stores the calculated transport distance FD in the RAM 74 and the nonvolatile memory 75.

  While the processes of steps S412 to S414 are being performed, the feeding operation of the first medium P in step S411 is continued. After the first medium P is detected by the second sensor 52, a skew removal operation is performed in which the leading end of the first medium P abuts on the transport roller pair 33 that is not rotating to correct the skew. After the end of the skew removing operation, the normal rotation drive of the feed motor 41 and the drive of the transport motor 44 are performed in synchronization, and the first medium P is the same as the intermediate roller 30 and the transport roller pair 33. By rotating at the transport speed (peripheral speed), the print head 38 is transported (searching out) to the printing start position which is the transport position of the medium P when printing is started. This cueing operation is performed as the first transport operation in step S420, which will be described later, in this routine for performing print control on the first medium P. In the following, the medium P being printed (conveyed) before printing is referred to as a preceding medium P1, and the medium P fed (conveyed) next to the preceding medium P1 is referred to as a succeeding medium P2. Therefore, the first medium P becomes the preceding medium P1.

  In step S415, it is determined whether the next path is the last path. This determination is made at the timing before the start of the transport operation for transporting the preceding medium P1 to the print position of the next pass for printing the next line. If it is not the last pass, the process proceeds to step S416, and if it is the last pass, the process proceeds to step S423. When the preceding medium P1 is transported to the printing start position on the first line, this determination process is performed at the timing after the skew removing operation is completed and before the cueing operation is started.

  In step S416, it is determined whether the overlapping operation has been performed. The computer 62 has a flag in the storage unit that sets “0” before the superposition operation is performed and “1” when the superposition operation is performed. It is determined that there is, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has not been performed, the process proceeds to step S417. If the overlapping operation has been performed, the process proceeds to step S420.

  In step S417, it is determined whether the first sensor has been switched from ON to OFF. That is, the computer 62 determines whether or not the rear end of the preceding medium P1 has deviated from the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 is switched from ON to OFF, the process proceeds to step S418, and if not, the process proceeds to step S420. When the first sensor 51 switches from ON to OFF, the computer 62 causes the first counter 81 to perform a counting process, and obtains the rear end position Y1 of the preceding medium P1 from the counted value.

  In step S418, it is determined whether or not overlapping is possible. In other words, it is determined whether or not a superimposable condition, which is a precondition for performing continuous superimposition, is satisfied. A superimposable condition including a margin condition including that the rear end position Y1 of the preceding medium P1 is within the superimposable area LA (LL ≦ Y1 <LU) and a print ink amount condition having a print duty equal to or less than a threshold are satisfied. It is determined whether or not. If the superimposable condition is satisfied, the process proceeds to step S419. If the superimposable condition is not satisfied, the process proceeds to step S420.

  In step S419, an overlapping operation is performed. Specifically, when the first sensor 51 is switched from ON to OFF (a positive determination is made in S414), the computer 62 drives the feed motor 41 in the normal direction, and rotates the feed roller 28 and the intermediate roller 30 to rotate the feed roller 41. The succeeding medium P2 is fed to the standby position Yw. In this feeding process, the computer 62 causes the first counter 81 to perform a counting process, thereby acquiring the rear end position Y1 of the preceding medium P1 from the counted value. In this overlapping operation, the normal rotation drive of the feed motor 41 is continued until the succeeding medium P2 reaches the standby position Yw at a transport speed higher than the transport speed of the preceding medium P1 during printing. Specifically, the computer 62 reads the transport distance FD from the RAM 74, and sets the actual transport distance of the subsequent medium P2 from the detection position of the first sensor 51 indicated by the count value of the first counter 81 to the target transport distance FD. Continue the stacking operation until it reaches. When the actual transport distance indicated by the count value of the first counter 81 matches the target transport distance FD, the driving of the feed motor 41 is stopped, and the stacking operation is completed. As a result of this overlapping operation, the succeeding medium P2 is fed until its leading end reaches the standby position Yw.

  When the computer 62 completes the overlapping operation, the value of the flag is changed from “0” to “1”. The printing device 12 receives the print data for each pass, and stores only a few passes of print data in the storage unit. Therefore, the trailing margin length and the leading margin length are printed in the last pass of this page. In some cases, the data cannot be acquired until the data and the print data of the first pass of the next page are received. In this case, even if the first sensor 51 detects the rear end of the preceding medium P1, it is impossible to determine whether or not the superimposable condition is satisfied. In such a case, the determination of the success or failure of the superimposable condition is performed at the time when the necessary print data is obtained. The superimposition operation is performed first before the determination, and the succeeding medium P2 is caused to wait at the standby position Yw. deep.

  In step S420, the carrying operation is performed to the printing position of the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. For example, when the next line is the first line, the preceding medium P1 is located at the print start position (see FIG. 7).

  In step S421, a printing operation for one pass is performed. The computer 62 drives the carriage motor 48 to move the carriage 36 by one pass in the scanning direction X, and causes the print head 38 to eject ink droplets from the nozzles 382 based on print data during the one pass movement. Then, a printing operation for printing an image for one pass on the preceding medium P1 is performed.

  In step S422, it is determined whether printing of one page has been completed. That is, it is determined whether the printing operation of all the lines of the preceding medium P1 has been completed. If printing of one page has not been completed, the process returns to step S412, and if printing of one page has been completed, the process proceeds to step S429.

  When the process returns to step S415, the processes in steps S415 to S422 are repeated until the last pass is reached in step S415. At this time, if the stacking operation has been performed (flag = “1”), the transport operation to the next line (S420) and the printing operation for one pass to the next line (S421) are substantially alternately performed. By doing so, printing on the preceding medium P1 is advanced. On the other hand, if the overlapping operation has not been performed (flag = “0”), the first sensor 51 switches from ON to OFF before reaching the last pass (NO in S415) (YES in S417), and the overlapping is possible. When the condition is satisfied (Yes in S418), the overlapping operation is performed (S419). Before the last pass, the first sensor 51 detects the rear end of the preceding medium P1, and if the superimposable condition is satisfied at that time, the superimposing operation is performed.

  Then, when the printing operation of the pass immediately before the last pass is completed, the process returns to step S415, and it is determined whether or not the next pass is the last pass. This determination is made during the period from the end of the printing operation of the pass (n-1st pass) immediately before the last pass (n-th pass) to the start of the transport operation of the preceding medium P1 to the printing position of the last pass. When the next pass is the last pass, the process proceeds to step S423.

  In step S423, it is determined whether or not the overlapping operation has been performed. The computer 62 determines whether or not the overlapping operation has been performed based on the value of the flag. That is, if the value of the flag is “1”, it is determined that the overlapping operation has been performed, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has been performed, the process proceeds to step S424. If the overlapping operation has not been performed (if the overlapping operation has not been performed), the process proceeds to step S420.

  If the superimposition operation has not been performed, the continuous superimposition cannot be performed. Therefore, the conveyance operation (S420) to the next line (the printing position of the last pass) and the printing operation of one line (one line of the last pass) (S421). ) And do. When printing of the last pass is completed in this way and printing of one page of the preceding medium P1 is completed (Yes in S422), in step S429, a discharging operation of discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. In this way, when the printing of the preceding medium P1 is completed and the printing control routine of the first sheet (first page) is completed, the succeeding medium P2 up to that becomes the preceding medium P1, and the third sheet (third page) is newly succeeded. It becomes the medium P2. Then, the computer 62 again executes the print control routine shown in FIG. 14 for printing the next page, and performs the feeding operation of the succeeding medium P2 as a new preceding medium P1 in step S411. At this time, since the preceding medium P1 of the first page has already been discharged, the discharging of the preceding medium P1 and the feeding of the succeeding medium P2 are performed with an interval therebetween. On the other hand, if the next pass is the last pass (Yes in S415) and the overlapping operation has been performed (Yes in Step S423), the process proceeds to Step S424.

  In step S424, the transport operation is performed until the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line.

  In step S425, a printing operation for one pass is performed. That is, the computer 62 drives the carriage motor 48 to cause the carriage 36 to move in the last pass, and prints the last line by ejecting ink droplets from the nozzles of the print head 38 during the movement process.

  In the step S426, it is determined whether or not the continuous feeding is possible. Here, it is determined whether or not the succeeding medium P2 that has completed the stacking operation is in a stacking ready state waiting at the standby position Yw. If it is possible to repeat the continuous feeding, the process proceeds to step S427. If not, the process proceeds to step S429. It should be noted that, in addition to being in a state of completion of stacking preparation, from the actual positions of the media P1 and P2 based on the current position information of the media P1 and P, for example, the rear end position Y1 of the preceding medium P1 is LL ≦ Y1 <LU. For example, it may be determined whether or not at least one condition for confirming that the position of the medium is at a position at which the continuous feeding can be performed, such as determining whether or not the position is a position that satisfies the above condition.

In step S427, a skew removing operation is performed. More specifically, when the drive of the transport motor 44 is stopped to end the transport operation for transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the carriage motor 48 to perform the printing operation. During the printing operation, while the transport motor 44 is stopped, the feed motor 41 is driven by a predetermined drive amount, and the leading end of the succeeding medium P2 is brought into contact with the transport roller pair 33 whose rotation is stopped, whereby the skew of the succeeding medium P2 is reduced. Skew correction operation to correct the skew.
When the drive of the transport motor 44 is stopped to end the transport operation of transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the feed motor 41 and starts transporting the subsequent medium P2 from the standby position Yw. A skew removing operation is performed in which the leading end of the lever abuts against the pair of transport rollers 33 whose rotation is stopped.

  Then, in the next step S428, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the conveying motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are The continuous feeding (hatched portion in FIG. 6) in which the sheets are transported at the same transport speed while maintaining the overlapping amount is performed. As a result, the succeeding medium P2 is moved to the printing start position while maintaining the overlapping amount with the preceding medium P1. As shown in FIG. 6, when the printing of the last line of the first sheet is completed, the first sheet P1 and the second sheet P2 are placed in at least a part of the margin area of the preceding sheet P1. The paper P is conveyed together while maintaining the state in which the leading ends overlap, and the second medium P2 is located at the print start position. In the case of this overlapping feeding system, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the transport amount when the cueing of the succeeding medium P2 to the printing start position is limited to the preceding medium P1. Is relatively small as compared with the transport amount in the normal feeding method in which the succeeding medium P2 is caught at an interval. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, in step S429, an operation of discharging the preceding medium is performed. At this time, the succeeding medium P2 is at the standby position Yw when the overlapping operation is performed, and is located upstream of the standby position Yw when the overlapping operation is not performed. Therefore, even if the transport motor 44 is driven to rotate the transport roller pair 33 and the discharge roller pair 34, only the preceding medium P1 is discharged, and the subsequent medium P2 waits at the position at that time.

  If there is a next page, after the discharging operation of the preceding medium P1 is completed, the feeding operation of the medium P of the next page is performed in step S411. However, since the next medium (previous succeeding medium P2) is stopped at the standby position Yw or a position slightly upstream from the standby position Yw, the feeding operation of the preceding medium P1 (previous succeeding medium P2) is performed. As a result, a new (second page) preceding medium P1 is located at the print start position. If the rear end position Y1 has passed the second nip position NP2 by a predetermined distance or more during the printing operation of the last pass, the skew removing operation of the succeeding medium P2 is performed during the printing operation of the last pass, and After the end of the printing operation, the ejection of the preceding medium P1 and the cueing of the succeeding medium P2 may be performed with an interval therebetween. During the ejection of the preceding medium P1, the computer 62 starts driving the feed motor 41 at a timing when the rear end of the preceding medium P1 passes the transport roller pair 33 and a certain interval is secured, and the skew is removed. The transport operation of the subsequent medium P2 to the print start position may be started. Further, when the printing of the last pass is started during the overlapping operation, the leading end of the succeeding medium P2 during the overlapping operation is directly abutted against the transport roller pair 33 that is not rotating, so that the overlapping operation and the skew removing operation can be performed simultaneously. Operation may be performed.

  As described above, according to the overlap feeding method of the present embodiment, the transfer position accuracy by the overlapping operation of the subsequent medium P2 is improved. For this reason, the minimum overlapping amount Lmin can be set to a smaller value, and the frequency of continuous continuous feeding can be improved. That is, if there is a variation in the stop position accuracy at which the succeeding medium P2 stops at the standby position Yw, it is necessary to set the minimum overlap amount Lmin in consideration of the variation. This is because when the trailing end of the preceding medium P1 and the leading end of the succeeding medium P2 do not overlap due to variation in the stop position accuracy of the succeeding medium, the end faces of the mediums P1 and P2 abut against each other and cause a jam. It may be. In addition, the stacking order is reversed, and the succeeding medium P2 is not overlaid on the preceding medium P1 on its front surface (printing surface) side. This causes a printing error in which the first line to be printed on the succeeding medium P2 is printed on the preceding medium P1 on the preceding medium P1.

  In addition, it is convenient for increasing the overlapping amount that the leading end of the succeeding medium P2 in the overlapping operation is as close as possible to the nip position NP2 of the transport roller pair 33. However, if the standby position Yw is too close to the nip position NP2 of the conveying roller pair 33, the leading end of the succeeding medium P2 hits the conveying roller pair 33 due to variation in the stop position accuracy of the succeeding medium P2, and is conveyed together with the preceding medium P1. There is a risk of being done. Therefore, it is necessary to set the standby position Yw in consideration of this kind of variation. However, in the present embodiment, since the stop position accuracy for stopping the succeeding medium P2 at the standby position Yw can be made relatively high, the standby position Yw can be made as close as possible to the nip position NP2 of the transport roller pair 33. For this reason, the lower limit LL can be reduced. As a result, after the printing of the preceding medium is completed, it is possible to increase the frequency of performing the continuous continuous feeding in which the rear end of the preceding medium P1 and the front end of the succeeding medium P2 are transported together in a partially overlapped state. By increasing the frequency of the continuous feeding, the printing throughput is improved.

According to the fifth embodiment described in detail above, the following effects can be obtained.
(5-1) An example of the first drive amount from the detection position S1 where the first sensor 51 detects the medium conveyed by the conveyance mechanism to the detection position S2 where the second sensor 52 detects the medium conveyed by the conveyance mechanism. Is measured by the second counter 82. The transport distance FD as an example of the second drive amount when the feed motor 41 of the transport mechanism 24 is driven from the detection position S1 of the first sensor 51 to the standby position Yw (an example of a predetermined position) based on the inter-sensor distance SD. to correct. Therefore, by driving the feed motor 41 from the detection position of the first sensor 51 by the second drive amount corresponding to the corrected transport distance FD, the subsequent medium P2 is stopped at the standby position Yw with relatively high stop position accuracy. Can be done. Therefore, even if an error in the stop position accuracy of the standby position Yw is taken into account, the overlapping condition can be set under a wider condition. Compared to a configuration in which the possible conditions need to be set, the frequency of performing the continuous feeding can be increased. For this reason, when printing is performed by the overlap feeding method, the printing throughput is improved.

  (5-2) The standby position Yw is set at a position between the second sensor 52 and the nip position NP2 at which the medium is nipped at the second roller. Based on a first drive amount corresponding to a distance SD between the detection positions S1 and S2 of the first sensor 51 and the second sensor 52, a nip position NP2 of the transport roller pair 33 as an example of a second roller from the first sensor. The second drive amount up to the standby position Yw set on the upstream side of the transport path is corrected. Therefore, the stop position accuracy when the succeeding medium P2 is transported to the standby position Yw through the first sensor 51 and stopped can be improved.

  (5-3) The controller 50 sets the first drive amount indicated by the counter equivalent value of the distance SD from the detection position S1 where the first sensor 51 detects the medium P to the detection position S2 where the second sensor 52 detects the medium P. It is measured by the second counter 82. Further, based on the first drive amount, the control unit 50 indicates the value corresponding to the counter of the transport distance FD when driving the feed motor 41 constituting the transport mechanism 24 from the detection position S1 of the first sensor 51 to the standby position Yw. The second drive amount is corrected. Thereafter, when the succeeding medium is fed at a feeding speed higher than the transport speed of the preceding medium and the overlapping operation of partially overlapping the preceding medium is performed, the overlapping operation is performed with the corrected second drive amount. In addition, the stop position accuracy of the succeeding medium to the standby position, which is the target position of the overlapping operation, can be improved. Thereafter, continuous feeding is performed to convey the preceding medium P1 and the succeeding medium P2 together with the preceding medium P1 and the succeeding medium P2 having completed the overlapping operation while maintaining the overlapping amount at that time. By increasing the stop position accuracy of the overlapping operation, it is possible to increase the frequency of performing the continuous overlapping feeding.

  (5-4) In the nonvolatile memory 75 as an example of the storage unit, the non-volatile memory 75 from the detection position S2 of the second sensor 52 to the nip position NP2 for nipping the medium P of the transport roller pair 33 as an example of the second roller is provided. Data of a driving amount ND (a distance ND corresponding to the driving amount) is stored as an example of the three driving amounts. When performing continuous printing on a plurality of media, the control unit 50 corresponds to the distance SD from the detection position S1 of the first sensor 51 to the detection position S2 of the second sensor 52 when the first medium P is transported. The first drive amount is measured, and the second drive amount is corrected based on the first drive amount and the third drive amount. Therefore, the second drive amount indicated by the counter value of the transport distance FD can be appropriately corrected.

(2 of the fifth embodiment)
Next, the configuration and control contents of the printing apparatus 12 according to the second embodiment of the fifth embodiment will be described with reference to FIGS. 58 to 60, the second sensor 52 is omitted. As shown in FIGS. 58 to 60, a fourth sensor 84 shown in FIG. 58 or 59 and a fifth sensor 85 shown in FIG. 60 are provided near the nip position NP2 of the transport roller pair 33. . By the way, the contact type sensor including the lever 52A like the second sensor 52 cannot detect the presence or absence of the medium P unless there is a gap (interval) of a predetermined length or more between the preceding medium P1 and the succeeding medium P2. On the other hand, the fourth sensor 84 shown in FIG. 58 or 59 can position the leading end of the succeeding medium P2 even when the trailing end of the leading medium P1 and the leading end of the succeeding medium P2 overlap. Can be detected. The fifth sensor 85 shown in FIG. 60 can detect a small gap between the media P1 and P2, which cannot be detected by a contact sensor such as the second sensor 52. When the fifth sensor 85 detects a slight gap between the preceding medium P1 and the succeeding medium P2 after the end of the stacking operation, the computer 62 determines that the stacking operation has failed because the stacking operation has failed. In this example, the fourth sensor 84 shown in FIG. 58 is an ultrasonic sensor 86, and the fourth sensor 84 shown in FIG. 59 is a lever sensor 87. The fifth sensor 85 shown in FIG. 60 is an optical sensor 88.

Hereinafter, the configuration of each of the fourth sensor 84 and the fifth sensor 85 will be described in order.
The fourth sensor 84 shown in FIG. 58 is an ultrasonic sensor 86, and includes an oscillator 86A that oscillates an ultrasonic wave and a receiver 86B that receives the ultrasonic wave oscillated from the oscillator 86A. The ultrasonic sensor 86 sets a relatively wide range around the standby position Yw in the transport direction Y as the detection range UA. The lower limit of the detection range UA is, for example, the second nip position NP2, and the upper limit is a position upstream of the standby position Yw by a distance equal to the distance between the second nip position NP2 and the standby position Yw.

  A fourth sensor 84 shown in FIG. 59 is a lever sensor 87, and includes a lever 87B made of a long rod or a rectangular plate rotatable around a rotation shaft 87A, and a rotation shaft 87A of the lever 87B. And a sensor 87C capable of detecting the end (the upper end in FIG. 59) on the side farther from the camera. When the end (lower end in FIG. 59) of the lever 87B closer to the rotation axis 87A comes into contact with the front end of the succeeding medium P2 and is displaced, the amount of displacement is increased by a large amount of displacement enlarged by the principle of leverage. Is displaced. For this reason, even a slight displacement of the lower end of the lever 87B can be detected, so that the fact that the leading end Y2 of the succeeding medium P2 has reached the standby position Yw can be detected with relatively high positional accuracy.

  The fifth sensor 85 shown in FIG. 60 is an optical sensor 88, and includes a light-emitting unit 88A and a light-receiving unit 88B that are located opposite to the standby position Yw across the transport path. If there is no medium P between the light emitting unit 88A and the light receiving unit 88B, the light sensor 88B receives the light from the light emitting unit 88A, and the optical sensor 88 enters a detection state (for example, an ON state). On the other hand, if the preceding medium P1 and the succeeding medium P2 that has completed the overlapping operation partially overlap between the light emitting unit 88A and the light receiving unit 88B, the light from the light emitting unit 88A is blocked by the mediums P1 and P2. The optical sensor 88 is in a non-detection state (for example, OFF state) because the light is not received by the light receiving unit 88B. As shown in FIG. 60, when there is a slight gap between the preceding medium P1 and the succeeding medium P2 at the time of completion of the superposing operation, and the optical sensor 88 is in the detection state, the computer 62 determines that the superposing operation has failed. .

  In the present embodiment, the computer 62 performs stop control of the subsequent medium P2 to the standby position Yw based on the detection signal of the fourth sensor 84 shown in FIG. 58 or FIG. 59 in which the position detection accuracy of the subsequent medium P2 is relatively high. 60, a failure of the overlay operation is detected based on a detection signal of the fifth sensor 85 for detecting an overlay operation failure shown in FIG. The non-volatile memory 75 stores a program PR of a superimposition operation control routine shown in the flowchart of FIG. 61 for controlling the superimposition operation based on each detection signal of the fourth sensor 84 and the fifth sensor 85. The computer 62 controls the overlapping operation of the succeeding medium P2 by executing the overlapping operation control program PR.

  In the superposing operation, the computer 62 of this embodiment transports the succeeding medium P2 at a high speed at a transport distance (FD-Δy) shorter than the transport distance FD in 1 of the fifth embodiment by a distance Δy for position adjustment. At this time, since the succeeding medium P2 is conveyed at high speed, although the conveyance distance FD based on the measured value is used, the stop position accuracy is relatively coarse. After that, the computer 62 performs a stop control to convey the succeeding medium P2 at a low speed by the position adjustment distance Δy and stop the succeeding medium P2 at the standby position Yw based on the detection signal of the fourth sensor 84. Further, after stopping the subsequent medium P2 at the standby position Yw, the computer 62 determines whether or not the overlapping operation has failed based on the detection signal of the fifth sensor 85.

  Next, the operation of the printing apparatus 12 configured as described above will be described. The computer 62 controls the overlapping operation based on the detection signals of the fourth sensor 84 for detecting the position and the fifth sensor 85 for detecting the failure of the overlapping operation. The computer 62 of this embodiment performs the transport control shown in FIG. 57 in the same manner as in the fifth embodiment, and performs the overlay operation control routine shown in FIG. 61 as control of the overlay operation in step S419 in FIG. Execute

  First, in step S431, the subsequent medium is fed by the transport distance FD-Δy. That is, the computer 62 drives the feeding motor 41 until the count value of the first counter 81 reaches the transport distance FD-Δy after the first sensor 51 detects the rear end of the preceding medium P1, and At the position upstream of the standby position Yw by the distance Δy. In the feed control at this time, the distance SD between the sensors measured when the first medium P is fed and the distance SD measured in the past are used as an average distance SDave which is a plurality of average values. The calculated transport distance FD (= SDave + ND-yn) is used. For this reason, the subsequent medium P2 is fed with relatively high positional accuracy by the feeding of the transport distance FD-Δy to a position (upstream side) before the standby position Yw by a position adjustment distance Δy.

  In the next step S432, low-speed transport of the succeeding medium is started. That is, the computer 62 switches the driving speed of the feeding motor 41 from high speed to low speed. Note that the computer 62 may temporarily stop driving the feeding motor 41 at a high speed and then restart driving the feeding motor 41 at a low speed.

  In the next step S433, it is determined whether or not the fourth sensor has detected the succeeding medium that has reached the standby position. When the fourth sensor 84 detects the succeeding medium P2 that has reached the standby position Yw and switches from OFF to ON, the process proceeds to step S434. On the other hand, if the fourth sensor 84 does not detect the succeeding medium P2 that has reached the standby position Yw and remains OFF, the control waits until the fourth sensor 84 detects the succeeding medium P2 and switches to ON.

  In step S434, the low-speed conveyance is stopped. That is, the computer 62 stops driving the feed motor 41. As a result, the succeeding medium P2 stops at the standby position Yw. In this way, the subsequent medium P2 is conveyed at a high speed to the position just before the standby position Yw by a distance ΔY for position adjustment from the standby position Yw and then conveyed at a low speed, and the fourth sensor 84 is moved to the front end of the subsequent medium P2. Is detected, the driving of the feed motor 41 is stopped, and the feed motor 41 stops at the standby position Yw with high positional accuracy.

  In the next step S435, it is determined whether or not the fifth sensor has detected a gap. If the fifth sensor 85 detects the gap between the media P1 and P2 and the detection signal is in the ON state, the computer 62 proceeds to step S436, where the computer 62 has not detected the gap between the media P1 and P2 and has detected the detection signal. Is in the OFF state, the overlapping operation control routine ends.

  In step S436, the continuous feeding is stopped. The computer 62 changes the flag for stopping the continuous feeding from “0” to “1”. This flag is used together with determining whether or not the continuous feeding is possible in step S426 in FIG. 57, and the computer 62 sets this flag to a value indicating that the continuous feeding is stopped (for example, “1”). In this case, it is determined that the continuous feeding is not possible (No in S426). In this case, when the continuous feeding is stopped and the printing of the preceding medium P1 is completed, the discharge of the preceding medium P1 and the conveyance (cueing) of the succeeding medium P2 to the printing start position are performed between the two media P1 and P2. Opening is done.

  As described in detail above, according to the present embodiment, the superimposition operation is performed by performing high-speed transport of the succeeding medium P2 to a position before the standby position Yw by a distance Δy for position adjustment from the standby position Yw, and then switching to low-speed transport. Then, the subsequent medium P2 is transported at a low speed until the fourth sensor 84 detects the subsequent medium P2 that has reached the standby position Yw. In addition, since the high-speed conveyance during the stacking operation is controlled by using the conveyance distance FD based on the distance SD between the sensors measured in the process of feeding the first medium P, the comparison up to the position where the low-speed conveyance is switched is performed. The subsequent medium P2 can be transported with extremely high transport position accuracy. As a result, the succeeding medium P2 can be stopped at the standby position Yw with higher accuracy than in the first embodiment.

  As described above, according to the overlap feeding method of the present embodiment, the transfer position accuracy by the overlapping operation of the subsequent medium P2 is improved. For this reason, the minimum overlapping amount Lmin can be set to a smaller value, and the frequency of continuous continuous feeding can be improved. Further, in the present embodiment, since the stop position accuracy at which the subsequent medium P2 stops at the standby position Yw can be made relatively high, the standby position Yw can be made as close as possible to the nip position NP2 of the transport roller pair 33. For this reason, the lower limit LL can be reduced, and the frequency of performing the continuous continuous feeding in which the rear end of the preceding medium P1 and the front end of the succeeding medium P2 are conveyed together in a partially overlapped state after the printing of the preceding medium is completed is increased. be able to. As a result, the print throughput is improved.

  (5-5) The printing apparatus 12 further includes a fourth sensor 84 that is an example of a position sensor that detects that the succeeding medium P2 has reached the standby position Yw. The control unit 50 causes the medium following the medium P to be transported at a first transport speed to a set position upstream of the standby position Yw based on the corrected drive amount. The sheet is transported from the set position to the standby position Yw at a second transport speed lower than the first transport speed. At the position where the fourth sensor 84 detects the medium P, the driving of the feeding motor 41 is stopped. As a result, the succeeding medium P2 can be stopped at the standby position Yw with relatively high stop position accuracy.

  (5-6) The printing device 12 further includes a fifth sensor 85 that is an example of a gap sensor that can detect a gap between the preceding medium P1 and the succeeding medium P2 when the overlapping operation of the succeeding medium P2 is completed. After stopping the succeeding medium P2 at the standby position Yw, when the fifth sensor 85 detects a gap between the preceding medium P1 and the succeeding medium P2, the control unit 50 stops the continuous feeding. Therefore, when the stacking operation fails, the continuous stacking can be stopped. It is possible to avoid a situation in which the continuous feeding is improperly performed even though the preceding medium P1 and the succeeding medium P2 do not properly overlap.

The fifth embodiment can be changed to the following modes.
-As in the printing apparatus described in Patent Literature 1, the first sensor may be used to start the overlapping operation by detecting the leading end of the medium (subsequent medium) as a trigger.

  -The structure which does not perform continuous feeding may be sufficient. For example, in the configuration in which the superposing operation of superimposing the preceding medium P1 and the succeeding medium P2 is performed, the discharge after the printing of the preceding medium P1 and the cueing of the succeeding medium P2 are performed with an interval between both the media P1 and P2. When the subsequent medium P2 is transported to the target stop position where the stacking operation is completed, the transport control may be performed based on the corrected second drive amount.

<Sixth embodiment>
Next, a sixth embodiment will be described with reference to the drawings. The sixth embodiment is an example in which at least one of the guide member and the support member is movable so as to be movable to a plurality of positions including a guide position at which the medium P can be guided. Hereinafter, 1 to 5 of the sixth embodiment will be described in order.

(1 of the sixth embodiment)
First, a sixth embodiment will be described with reference to FIGS. In the present embodiment, the guide member and the support member are movable.

  As shown in FIG. 62, a flap member 550, which is an example of a movable guide member rotatable around a rotation shaft 551, is disposed immediately downstream of the intermediate roller 30 in the transport direction Y. A movable lower path member 572 slightly longer in the width direction X than the width of the transport path is disposed below the transport path of the medium P between the intermediate roller 30 and the transport roller pair 33.

  As shown in FIG. 63, the flap member 550 is supported by a pair of arms 552 rotatably provided around a rotation shaft 551, and extends over a predetermined rotation angle range around the rotation shaft 551. It is rotatable. A support member 57 that supports the medium P from below is disposed between the intermediate roller 30 and the transport roller pair 33. A movable lower path member 572 is provided at a position on the support member 57 slightly downstream of the flap member 550 in the transport direction Y so as to be vertically displaceable. The flap member 550 can protrude and retract from the guide surface 57A of the support member 57.

  Next, the configuration and operation of the guide member 55 and the lower path member 572 will be described with reference to FIG. Although the configuration is basically the same as that of the first embodiment, the present embodiment is different from the first embodiment in that a movable guide member 55 and a movable lower path member 572 are provided. As shown in FIG. 63, a flap member 550 for guiding the medium P is disposed at a position slightly downstream from a nip portion (first nip position NP1) between the intermediate roller 30 and the second driven roller 32. I have. The flap member 550 is supported at the distal end of an arm 552 supported by a frame (not shown) so that the base end can rotate around a rotation shaft 551. When the flap member 550 is at the guide position shown in FIG. 63, the medium P sent in the tangential direction at the nip position NP1 between the intermediate roller 30 and the second driven roller 32 is positioned above the tangential direction (with respect to the gravity direction Z and the gravitational direction Z). The feeding direction of the medium P is guided with the direction pointing to the position (opposite side) as the target direction. The guide direction (for example, horizontal direction) of the guide member 55 intersects with the guide surface 56A for upper route guidance. In this example, when the guide member 55 is arranged at the guide position, the guide surface (upper surface) is arranged in a posture where the guide surface (horizontal surface) is horizontal, and at the guide position, the sending direction is substantially horizontal as an example.

  As shown in FIG. 64, the lower path member 572 is rotatable around a rotation shaft 574 fixed to the downstream end in the transport direction Y. It moves between the evacuation position indicated by the dotted line. Further, the flap member 550 moves between the guide position shown in FIG. 63 and the retracted position shown in FIG. Then, in a state where the flap member 550 is located at the retracted position, the succeeding medium P2 hanging down from the first nip position NP1 while being nipped between the intermediate roller 30 and the second driven roller 32 is located at the guide position. The guide surface 573 of the lower path member 572 is supported. The guide surface 573 is formed in a concave curved surface shape having a radius of curvature increasing toward the downstream side in the cross section in FIG. 64 cut in parallel to the transport direction Y, and the subsequent medium P2 hanging down from the first nip position NP1 is curved by the guide surface 573. Supported as drawing. For example, if the lower path member 572 is not provided, there is a concern that the succeeding medium P2 will buckle, but there is no fear of buckling due to being supported by the lower path member 572 disposed at the guide position.

  As shown in FIG. 65, when the overlapping operation is performed, the flap member 550 is arranged at the guide position indicated by the solid line in FIG. 65, and the lower path member 572 is arranged at the retracted position indicated by the solid line in FIG. Therefore, the succeeding medium P2 is guided by the flap member 550 and is conveyed along a path near the upper limit position along the guide surface 56A. At this time, even if the rear end of the preceding medium P1 is located on the lower path member 572, the lifting is suppressed because the lower path member 572 is at the retracted position. When the stacking operation is completed, the flap member 550 is located at the retracted position shown by the two-dot chain line in the same figure, and the lower path member 572 is placed at the guide position shown by the two-dot chain line in the same figure. For this reason, the subsequent medium P2 is supported by the guide surface 573 of the lower path member 572 as shown by a two-dot chain line in the same figure, so that it draws a curve from the first nip position NP1 in a side view of the same figure. Hang down. For example, the force transmitted to the succeeding medium P2 by the rotation of the intermediate roller 30 during the skew removing operation is reliably transmitted to the leading end, and the leading end can be abutted against the transport roller pair 33 with a force required for skew removing. .

  Here, the reason why the flap member 550 and the lower path member 572 are movable will be described. For example, as in the above embodiments, when the guide member 55 is arranged in a substantially horizontal posture in which the subsequent medium P2 can be guided in a direction intersecting with the guide surface 56A, the succeeding medium P2 after the overlapping operation is located downstream of the guide member 55. It hangs down from the side edge. The sagging subsequent medium P2 is likely to buckle at a position in contact with the upper surface of the fixed support member 57 of the first embodiment. When the medium P is buckled, when the skew removing operation is performed, the force for sending out the succeeding medium P2 by the rotation of the intermediate roller 30 is transmitted to a downstream portion of the buckled portion, etc. Hateful. Therefore, when the skew removing operation is performed, the force of the leading end of the succeeding medium P2 abutting on the transport roller pair 33 becomes relatively weak, and it becomes difficult to perform an appropriate skew removing operation. Therefore, in each of the above-described embodiments, the support member 57 having the inclined guide surface 57A is disposed, and the middle of the portion hanging down from the guide member 55 in the horizontal posture is supported by the inclined guide surface 57A. The portion hanging down from the guide member 55 takes an S-shaped curve. For this reason, the force of sending the succeeding medium P2 from the intermediate roller 30 is reliably transmitted to the leading end of the succeeding medium P2, and the leading end can be abutted against the transport roller pair 33 with a relatively strong force.

  However, when the support member 57 having the inclined guide surface 57A is provided, the rear end of the preceding medium P1 is easily lifted up on the inclined guide surface 57A, and the leading end of the succeeding medium P2 fed by the overlapping operation. However, there is a possibility that the stacking order may be reversed up and down by entering below the raised rear end of the preceding medium P1.

  For this reason, in the present embodiment, the guide member is a movable flap member 550 movable between the guide position and the retracted position, and the flap member 550 is disposed in the retracted position in an obliquely downward posture, thereby being horizontally disposed. The buckling of the succeeding medium P2 due to the hanging from the guide member 55 is avoided.

  However, in the present embodiment, even if the succeeding medium P2 after the overlapping operation hangs down from the guide member 55 at the guide position in which it takes a horizontal posture, the part of the hang-down portion is replaced by the lower path member 572 arranged at the guide position. Are supported by the inclined guide surface 573. As a result, the succeeding medium P2 is supported along a path that draws an S-shaped curve, and the leading end of the succeeding medium P2 abuts on the transport roller pair 33 that has stopped rotating during the skew removing operation with an appropriate force. For this reason, even when the flap member 550 is located at the retracted position, the hardness and the like vary depending on the type of medium and the medium size, and a plurality of types of media P having different flexing methods and buckling easiness when hanging down. Also, by supporting the succeeding medium P2 on the guide surface 573 of the lower path member 572 at the guide position, it is possible to take an S-shaped curve path.

  In addition, since the support member 57 does not need to support the subsequent medium P2 after the overlapping operation so as to take a curved path, the support member 57 is formed so that the guide surface 57A is located low around a portion corresponding to the lower path member 572. Have been. For this reason, the support member 57 is configured such that the guide surface 57A has a gentler curve and a lower height than the support member 57 in the first embodiment, and when the lower path member 572 is disposed at the retracted position, the guide surface 57A 57A and the guide surface 573 are located low. Even if the rear end portion of the preceding medium P1 is placed on the guide surfaces 57A and 573 during the superimposing operation, it is hard to be lifted.

  Next, an electrical configuration of the printing apparatus 12 will be described with reference to FIG. The electrical configuration of the printing apparatus 12 is basically the same as in the first and second embodiments, except that an actuator for driving the flap member 550 and the lower path member 572 is provided. As shown in FIG. 66, a first solenoid 91 that is a power source for driving the flap member 550 and a second solenoid 92 that is a power source for driving the lower path member 572 are electrically connected to the control unit 50. I have. More specifically, a first solenoid 91 is electrically connected to a computer 62 of the control unit 50 via a drive circuit 67 (excitation / demagnetization circuit), and a second solenoid is connected via a drive circuit 68 (excitation / demagnetization circuit). 92 are electrically connected.

  When the computer 62 excites the first solenoid 91, the flap member 550 is located at the guide position, and when demagnetized, the flap member 550 is located at the retracted position. The lower path member 572 is urged toward the guide position by, for example, a spring (not shown). When the computer 62 excites the second solenoid 92, the lower path member 572 is disposed at the retracted position, and the second solenoid 92 Is demagnetized, the lower path member 572 is arranged at the guide position. The non-volatile memory 75 stores a print control program PR and the like shown in the flowchart of FIG. Since the flap member 550 is located at the retracted position after the stacking operation, there is no need to worry that the rear end of the preceding medium P1 is placed on the flap member 550 after the stacking operation. The upper limit position YU of the overlappable area LA defining the condition is set at the first nip position NP1.

  Next, with reference to FIG. 67 to FIG. 73, a description will be given of the content of the transport control in the overlap feeding method. This stack feeding method includes a stacking operation and a stack continuous feeding. Note that the control contents of the feed motor 41, the transport motor 44, and the carriage motor 48 are the same as those in the first embodiment and the like, and therefore the description will be focused on the control of the first solenoid 91 and the second solenoid 92. In FIG. 67, the excitation of each of the solenoids 91 and 92 is shown as ON, and the demagnetization is shown as OFF.

  As shown in FIG. 67, before the start of printing, the solenoids 91 and 92 are in a demagnetized state, the flap member 550 is lowered to the retreat position, and the lower path member 572 is raised to the guide position. In this state, the first medium P is fed by the forward rotation of the feed motor 41.

  The topmost preceding medium P1 is fed out of the cassette 21 by the rotation of the feed roller 28 shown in FIG. 68 and is separated into one sheet. Then, the two driven rollers 31, The sheet is fed toward the pair of conveying rollers 33 in a state where the sheet is nipped between the conveying roller 32 and the conveying roller pair 33. During the feeding, the leading medium P1 is skewed by abutting the leading end against the conveying roller pair 33 that is not rotating, and is then conveyed to the print start position (heading). At this time, the flap member 550 is at the retracted position, and the support member 57 is at the guide position. For this reason, since the portion of the preceding medium P1 hanging down from the nip position NP1 between the intermediate roller 30 and the driven roller 32 is supported by the concave guide surface 57A of the support member 57, a path that draws an S-shaped curve is taken. At this time, the leading end of the preceding medium P1 is abutted against the transport roller pair 33 during rotation stop with an appropriate force, and the skew is appropriately corrected.

  Next, as shown in FIG. 67, after the leading medium P1 is located, the printing operation performed by moving the printing unit 25 by driving the carriage motor 48, and the driving of the feeding motor 41 and the conveying motor 44 are performed. Accordingly, the transport operation for transporting the preceding medium P1 is performed substantially alternately. As the printing proceeds, the preceding medium P1 is intermittently conveyed to the downstream side in the conveying direction Y, and the feeding roller 28 abuts on the following medium P2 during the printing, and the feeding of the succeeding medium P2 is started. Due to the speed difference between the feeding roller 28 and the intermediate roller 30, the interval between the succeeding medium P2 sent from the cassette 21 and the succeeding medium P2 gradually increases as the conveyance of the preceding medium P1 proceeds.

  As shown in FIG. 68, the rear end of the preceding medium P1 comes off the nip (first nip position NP1) between the intermediate roller 30 and the second driven roller 32, and as shown in FIG. When the rear end is detected and switched from ON to OFF, the driving speed of the feeding motor 41 being driven at that time is switched to a speed higher than the speed during the transport operation. As a result, as shown in FIG. 69, the overlapping operation of the succeeding medium P2 (catch-up feeding operation) is started. Also, when the first sensor 51 detects the trailing end Y1 of the preceding medium P1 as a trigger, the first solenoid 91 is driven to be excited, so that the guide member 55 moves from the retracted position shown by the solid line in FIG. It moves to the guidance position shown by the two-dot chain line. At this time, the excitation of the second solenoid 92 causes the support member 57 to move from the guide position indicated by the solid line in FIG. 69 to the retracted position indicated by the two-dot chain line in FIG.

  In the overlapping operation shown in FIG. 70, the succeeding medium P2 is fed to the standby position Yw (see FIG. 71), which is the target position, at a feed speed higher than the transport speed of the preceding medium P1 being printed. At this time, as shown in FIG. 70, the succeeding medium P2 sent out in the tangential direction from the nip portion (first nip position NP1) between the intermediate roller 30 and the second driven roller 32 by the overlapping operation is moved to the first nip position NP1. Is guided in a substantially horizontal direction by the flap member 550 disposed at the guide position in the vicinity of the downstream side, and is conveyed along the guide path 56A for upper route guidance. Further, since the support member 57 is at the retracted position, even if the rear end of the preceding medium P1 is at a position corresponding to the support member 57, the support member 57 is lifted up by the retracted amount compared to the case where the support member 57 is at the guide position. It becomes difficult. Therefore, the succeeding medium P2 is fed to the standby position Yw through the upper path along the guide surface 56A with respect to the rear end of the preceding medium P1 that is unlikely to float due to the retreat of the support member 57 due to the overlapping operation. The leading end of the succeeding medium P2 is superimposed on the trailing end of the preceding medium P1 in an appropriate state.

  As shown in FIG. 67, immediately after the first sensor 51 detects the leading end of the succeeding medium P2 and switches from OFF to ON immediately after the start of the stacking operation, the feed motor 41 drives the drive amount according to the target transport amount. The drive is stopped after being driven only. As a result, as shown in FIG. 71, the succeeding medium P2 stops at the position where the leading end reaches the standby position Yw. The succeeding medium P2 that has completed the superposition operation waits at the standby position Yw until the last pass printing operation for printing the last line on the preceding medium P1 is performed. Then, as shown in FIG. 67, if the determination of the predetermined time before the start of the printing operation of the last pass shows that the superimposable condition is satisfied, the feed motor 41 is driven to rotate forward during the printing operation of the last pass, and as shown in FIG. As described above, the skew of the succeeding medium P2 is corrected by performing the skew removing operation in which the leading end of the succeeding medium P2 is brought into contact with the transport roller pair 33 whose rotation is stopped. During the skew removing operation, the hanging portion of the succeeding medium P2 is supported by the concave guide surface 57A of the support member 57, so that the succeeding medium P2 has an S-shaped portion from the first nip position NP1 to the standby position Yw. Take the curve path. The force at the time of pushing out the succeeding medium P2 by driving the feed motor 41 is transmitted to the leading end through the path of the S-shaped curve, and the leading end is abutted against the transport roller pair 33 during the rotation stop with appropriate strength. .

  As shown in FIG. 67, when the printing operation of the last pass is completed, the feed motor 41 and the transport motor 44 are driven in synchronization, and the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 have the same transport speed (peripheral speed). ), And the continuous feeding is performed. That is, the continuous feeding in which the preceding medium P1 and the succeeding medium P2 are transported together at the same transport speed while maintaining the overlapping amount LP (see FIG. 72) at that time until the succeeding medium P2 reaches the printing start position. Is performed. As a result of the continuous continuous feeding, as shown in FIG. 73, the succeeding medium P2 is moved to the printing start position with the leading end of the succeeding medium P2 overlapping the trailing margin of the preceding medium P1.

  Next, the operation of the printing device 12 will be described. Hereinafter, with reference to FIGS. 65 and 67, a description will be given of the print control including the continuous paper feed performed by the computer 62 in the control unit 50 executing the program PR shown in the flowchart of FIG. 74. The computer 62 executes the program PR, for example, when receiving a print job from the host device 100. In the case of printing a plurality of sheets, first, the first medium is the preceding medium P1. When the preceding medium P1 is being printed, the second medium P fed after the preceding medium P1 is the succeeding medium P2.

First, in step S511, it is determined whether the medium can be overlapped based on the medium type, the medium size, and the feeding path. The determination result of the overlap possibility determination is used in a later step.
In the next step S512, the preceding medium is fed. That is, as shown in FIG. 67, the computer 62 drives the feed motor 41 in the normal rotation direction (CW direction) (forward rotation drive), and feeds the preceding medium P1 by the rotation of the feed roller 28 and the intermediate roller 30. Send. During the feeding, a skew removing operation is performed in which the leading end of the preceding medium P1 is abutted against the transport roller pair 33 whose rotation is stopped, and the skew of the preceding medium P1 is corrected. Next, the computer 62 synchronizes the normal rotation drive of the feed motor 41 and the drive of the transport motor 44, and moves the preceding medium P1 to the printing start position by the intermediate roller 30 and the transport roller pair 33 rotating at the same transport speed. Cue.

  In step S513, it is determined whether the next path is the last path. This determination is made at a timing before the start of the transport operation for transporting the preceding medium P1 to the printing position of the next pass. If it is not the last pass, the process proceeds to step S514, and if it is the last pass, the process proceeds to step S525. It should be noted that this determination may be made at a timing until the printing operation of the next pass is started.

  In step S514, it is determined whether or not the overlapping operation has been performed. The computer 62 has a flag in the storage unit that sets “0” before the superposition operation is performed and “1” when the superposition operation is performed. It is determined that there is, and if the value of the flag is “0”, it is determined that the overlapping operation has not been performed. If the overlapping operation has not been performed, the process proceeds to step S515. If the overlapping operation has been performed, the process proceeds to step S522.

  In step S515, it is determined whether the first sensor has been switched from ON to OFF. That is, it is determined whether or not the rear end of the preceding medium P1 has deviated from the first nip position NP1 and the first sensor 51 has detected the rear end. If the first sensor 51 detects the trailing end of the preceding medium P1 and switches from ON to OFF, the process proceeds to step S516. If not, the process proceeds to step S522. When the first sensor 51 switches from ON to OFF, the computer 62 causes the first counter 81 to perform a counting process, and obtains the rear end position Y1 of the preceding medium P1 from the counted value.

  In step S516, it is determined whether or not overlapping is possible. That is, it is determined whether or not a superimposable condition, which is a condition for performing continuous superimposition, is satisfied. A superimposable condition including a margin condition such as that the rear end position Y1 of the preceding medium P1 is within the superimposable area LA (LL ≦ Y1 <LU) and a print density condition that the print duty is equal to or less than a threshold are satisfied. It is determined whether or not. If the superimposable condition is satisfied and the superimposition is possible, the process proceeds to step S517, and if not, the process proceeds to step S522.

  In step S517, the flap member is moved to the guide position. That is, the computer 62 moves and arranges the flap member 550 to the guide position indicated by the solid line in FIG. 65 by exciting the first solenoid 91.

  In step S518, the lower path member is moved to the retracted position. That is, the computer 62 moves and arranges the lower path member 572 to the retracted position (non-guide position) indicated by a solid line in FIG. 65 by exciting the second solenoid 92. As shown in FIG. 65, when the trailing end Y1 of the preceding medium P1 is displaced from the first nip position NP1 and the trailing end Y1 is detected and the first sensor 51 switches from ON to OFF, the flap member 550 is moved to the retracted position. And the lower path member 572 moves from the guide position to the retracted position.

  In step S519, an overlapping operation is performed. Specifically, the computer 62 drives the feed motor 41 to rotate in the normal direction, and feeds the succeeding medium P2 to the standby position Yw by rotation of the feed roller 28 and the intermediate roller 30. In this overlapping operation, the succeeding medium P2 is fed at a speed higher than the speed of feeding the preceding medium P1 being printed, and the feeding motor 41 is driven until the succeeding medium P2 reaches the standby position Yw. In the overlapping operation process, the computer 62 causes the second counter 82 to start a counting process when the first sensor 51 detects the leading end of the succeeding medium P2 and switches from OFF to ON. Of the front end position Y2 of. When the leading end position Y2 reaches the standby position Yw, the driving of the feeding motor 41 is stopped. As a result, the succeeding medium P2 stops at the standby position Yw. When completing the overlay operation, the computer 62 changes the value of the flag from the value “0” for which the overlay operation has not been performed to the value “1” for which the overlay operation has been performed. Since the printing device 12 receives the print data for each pass and can store only print data for several passes in the storage unit, the trailing margin length and the leading margin length are set to the print data of the last pass of this page. In some cases, the configuration cannot be obtained until print data of the first pass of the next page is received. In this case, even if the first sensor 51 detects the rear end of the preceding medium P1, it is impossible to determine whether or not the superimposable condition is satisfied. In such a case, the determination of the success or failure of the superimposable condition should be made at the time when the necessary print data is obtained. By performing the operation, the succeeding medium P2 is caused to wait at the standby position Yw.

  In step S520, the flap member is moved to the retracted position. That is, the computer 62 demagnetizes the first solenoid 91 and moves the flap member 550 to the retracted position shown by the two-dot chain line in FIG.

  In the next step S521, the lower path member is moved to the guide position. That is, the computer 62 demagnetizes the second solenoid 92 and moves the lower path member 572 to the guide position indicated by the two-dot chain line in FIG. As shown in FIG. 65, when the overlapping operation of the succeeding medium P2 is completed, the flap member 550 moves from the guide position to the retreat position, and the lower path member 572 moves from the retreat position to the guide position. As a result, the subsequent medium P2 nipped between the intermediate roller 30 and the second driven roller 32 and hung from the first nip position NP1 to the standby position Yw is supported by the guide surface 573 of the lower path member 572, It is guided on a curved path along the guide surface 573. The curvature of the concave guide surface 573 has a value that can guide the subsequent medium P2 from the first nip position NP1 to the standby position Yw so as to draw a concave curve.

  In step S522, the carrying operation is performed to the printing position of the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line. If the preceding medium P1 is already at the printing position of the first line immediately after the cueing, this transport operation is omitted.

  In step S523, a printing operation for one pass is performed. The computer 62 drives the carriage motor 48 to move the carriage 36 by one pass in the scanning direction X, and the print head 38 ejects ink droplets from the nozzles 382 based on print data during the one pass movement process. Then, a printing operation for printing an image for one pass on the preceding medium P1 is performed.

  In step S524, it is determined whether printing of one page has been completed. That is, it is determined whether or not the printing operation of all the lines to be printed on the preceding medium P1 has been completed. If the printing of one page has not been completed, the process returns to step S513, and if the printing of one page has been completed, the process proceeds to step S531.

  When returning to step S513, thereafter, the processing of steps S513 to S524 is repeated until the last pass is reached in step S513. At this time, if the superimposition operation has been performed (flag = “1”) (Yes in S514), the transport operation to the next line (S523) and the printing operation for one pass in the next line (S524). Are performed substantially alternately, printing on the preceding medium P1 is advanced. On the other hand, if the overlapping operation has not been performed (flag = “0”), the first sensor 51 is switched from ON to OFF before reaching the last pass (NO in S513) (an affirmative determination in S515), and the overlapping enabled condition is satisfied. Is satisfied (Yes in S516), the overlapping operation is performed (S519). Before the last pass, the first sensor 51 detects the rear end of the preceding medium P1, and if the superimposable condition is satisfied at that time, the superimposing operation is performed.

  When the printing operation of the pass immediately before the last pass (the (n-1) th pass) is completed, the process returns to the step S513, and it is determined that the next pass is the last pass (the nth pass), so that the process proceeds to the step S525. .

  In step S525, it is determined whether or not the overlapping operation has been performed. The computer 62 determines whether or not the overlapping operation has been performed based on the value of the flag. That is, if the value of the flag is "1", it is determined that the overlapping operation has been performed, and if the value of the flag is "0", it is determined that the overlapping operation has not been completed. If the overlapping operation has not been performed, the process proceeds to step S522. If the overlapping operation has been performed, the process proceeds to step S526.

  If the overlapping operation has not been performed, the overlapping continuous feeding cannot be performed. Therefore, the carrying operation (S522) is performed to the printing position of the next last pass, and the printing operation for one line of the last pass (S523) is performed. When the printing operation of the last pass is completed in this way and the printing of one page of the preceding medium P1 is completed (YES in S524), in step S531, a discharging operation of discharging the preceding medium is performed. The computer 62 drives the feed motor 41 and the transport motor 44 to discharge the preceding medium P1. When the printing of the first preceding medium P1 is completed in this way and the first routine ends, in the next routine, the subsequent succeeding medium P2 becomes the preceding medium P1, and the third medium P becomes a new succeeding medium. It becomes P2. Then, the computer 62 again executes the print control routine shown in FIG. 74 for printing the next page, and in step S511, performs the feeding operation of the succeeding medium P2 as a new preceding medium P1. At this time, since the first precedent medium P1 has already been discharged, the discharge of the first precedent medium P1 and the feeding of the second precedent medium P1 are performed with an interval between the two media P. Done. On the other hand, if the next pass is the last pass (Yes in S513) and the overlapping operation has been performed (Yes in Step S525), the process proceeds to Step S526.

  In step S526, the transport operation is performed up to the next line. That is, the computer 62 drives the feed motor 41 and the transport motor 44 in synchronization with each other, rotates the feed roller 28, the intermediate roller 30, the transport roller pair 33, and the discharge roller pair 34 at the same transport speed, and P1 is transported to the printing position of the next line.

  In step S527, a printing operation for one pass is performed. That is, the computer 62 drives the carriage motor 48 to cause the carriage 36 to move in the last path, and in the course of the movement, ejects ink droplets from the nozzles 382 of the print head 38 to print the last line.

  In step S528, it is determined whether or not the continuous feeding is possible. Here, it is determined whether or not the succeeding medium P2 that has completed the stacking operation is in a stacking ready state waiting at the standby position Yw. If overlap continuous feeding is possible, the process proceeds to step S529; otherwise, the process proceeds to step S531. It should be noted that, in addition to being in a state of completion of stacking preparation, from the actual positions of the media P1 and P2 based on the current position information of the media P1 and P, for example, the rear end position Y1 of the preceding medium P1 is LL ≦ Y1 <LU. For example, it may be determined whether or not at least one condition for confirming that the position of the medium is at a position at which the continuous feeding can be performed, such as determining whether or not the position is a position that satisfies the above condition.

  In step S529, a skew removing operation is performed. More specifically, when the drive of the transport motor 44 is decelerated or stopped so as to end the transport operation for transporting the preceding medium P1 to the printing position of the last pass, the computer 62 drives the carriage motor 48 to perform the printing operation. In this printing operation, while the driving of the transport motor 44 is stopped, the feed motor 41 is driven to perform a skew removing operation in which the leading end of the succeeding medium P2 abuts on the transport roller pair 33 whose rotation is stopped. At this time, the subsequent medium P2 is guided by the guide surface 57A of the support member 57, and the path of the subsequent medium P2 from the first nip position NP1 to the standby position Yw draws a curved curve (for example, an S-shaped curve). Therefore, the force that pushes out the subsequent medium P2 by the rotation of the intermediate roller 30 while being nipped between the intermediate roller 30 and the driven roller 32 is transmitted to the leading end Y2 along the subsequent medium P2 that draws a curved curve. As a result, the leading end of the preceding medium P1 is relatively strongly pressed against the transport roller pair 33, so that the skew is appropriately corrected by the skew removing operation. When the printing of the last pass is started during the superposing operation, the superposing operation and the skew removing operation are performed in one operation by directly abutting the leading end of the succeeding medium P2 to the transport roller pair 33 that is not rotating. Is also good.

  Then, in the next step S530, overlapping continuous feeding is performed. That is, during the deceleration of the carriage motor 48 after the printing operation of the last pass on the preceding medium P1, the feeding motor 41 and the conveying motor 44 are driven synchronously, and the preceding medium P1 and the succeeding medium P2 are Overlapping continuous feeding (hatched portion in FIG. 67) of transporting the succeeding medium P2 to the printing start position at the same transport speed while maintaining the overlap amount is performed.

  As shown in FIG. 67, when the printing of the last line of the first sheet is completed, the first medium P1 and the second medium P2 are placed in at least a part of the trailing margin of the preceding medium P1. P2 is conveyed together while maintaining the overlapping state, and the second medium P2 is moved to the print start position. In the case of this overlapping feeding system, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 are advanced in one operation, and the transport amount when the cueing of the succeeding medium P2 to the printing start position is limited to the preceding medium P1. Is relatively small as compared with the transport amount in the normal feeding method in which the succeeding medium P2 is caught at an interval. As a result, the printing of the succeeding medium P2 can be started immediately after the printing on the preceding medium P1 is completed. Therefore, in the case of the double feeding method, the printing throughput is improved as compared with the normal feeding method.

  On the other hand, in step S531, an operation of discharging the preceding medium is performed. At this time, the succeeding medium P2 is at the standby position Yw when the overlapping operation is performed, and is located upstream of the standby position Yw in the transport direction Y when the overlapping operation is not performed. Therefore, even if the transport motor 44 is driven to rotate the transport roller pair 33 and the discharge roller pair 34, only the preceding medium P1 is discharged, and the subsequent medium P2 waits at the position at that time.

  If there is a next page, after the discharging operation of the preceding medium P1 is completed, the routine of FIG. 74 is executed again with the succeeding medium P2 as a new preceding medium P1. However, during the same print job, when the second or subsequent medium P is set as the preceding medium P1, the process of step S511 is skipped, and the feeding operation of the preceding medium P1 (the medium P of the next page) is performed in step S511. I do. At this time, since the next medium (previous succeeding medium P2) is stopped at the standby position Yw or a position slightly upstream from the standby position Yw, the feeding operation of the preceding medium P1 is started from the stopped position, and Of the preceding medium P1 at the print start position. If the rear end position Y1 is at a position that has passed the second nip position NP2 by a predetermined distance or more during the printing operation of the last pass, the skew removing operation of the succeeding medium P2 is performed during the printing operation of the last pass, and the last line of the preceding medium P1 is printed. After the end of the printing, the discharge of the preceding medium P1 and the cueing of the succeeding medium P2 may be performed with an interval therebetween. During the ejection of the preceding medium P1, the computer 62 starts driving the feed motor 41 at a timing when the rear end of the preceding medium P1 passes the transport roller pair 33 and a certain interval is secured, and the skew is removed. May be started to transport the subsequent medium P2 to the printing start position.

  In this way, the same number of routines as the number of printed sheets are repeatedly executed, and when the last sheet is printed, the preceding medium P1 alone and no succeeding medium P2 (next page) are present, so that the processing (S514 to S521, etc.) relating to the superposition operation is skipped. . Then, for example, the transport operation (S522) and the printing operation (S523) for the last sheet of the medium P that has been caught in the previous overlap continuous feeding (S530) are performed substantially alternately, and printing for one page is performed. . When the printing of one page is completed, the last sheet of medium P is discharged by a discharging operation (S531) (see also FIG. 67).

  As described above, according to the overlapping feeding method of the present embodiment, when starting the overlapping operation, the flap member 550 is moved from the retracted position to the guide position, and the support member 57 is moved and arranged from the guide position to the retracted position. . For this reason, the subsequent medium P2 sent out by the overlapping operation is guided in a substantially horizontal direction intersecting with the guide surface 56A for guiding the upper route, so that the subsequent medium P2 guided in the target direction follows the guide surface 56A. It is fed through the upper path. At this time, when the support member 57 is at the guide position, if the rear end of the preceding medium P1 is long enough to reach the support member 57, the rear end is easily lifted up on the support member 57, In particular, if the rear end is curled, the amount of lift is further increased. For example, if the rear end of the preceding medium P1 is raised, the succeeding medium P2 during the overlapping operation may collide with the raised rear end and may enter the lower side. However, in the present embodiment, since the support member 57 is retracted downward during the overlapping operation, the rear end of the preceding medium P1 is unlikely to float. As a result, the leading end of the succeeding medium P2 can be overlaid on the trailing end of the preceding medium P1. Therefore, when the direction in which the leading end of the succeeding medium P2 overlaps with the trailing end of the preceding medium P1 is reversed, the printing of the first line of the succeeding medium P2 is performed in the trailing margin of the preceding medium P1. Printing errors can be reduced.

According to the sixth embodiment described in detail above, the following effects can be obtained.
(6-1) an overlapping operation in which the succeeding medium P2 is fed at a feeding speed higher than the transport speed of the preceding medium P1 to partially overlap the preceding medium P1, and a skew removing operation in which the skew of the succeeding medium P2 is corrected. After the printing operation of the last line of the preceding medium P1 is completed, the successive medium P2 is sequentially conveyed to the printing start position while maintaining the overlapping state with the preceding medium P1. During the overlapping operation, the flap member 550, which is an example of a guide member, guides the feeding direction of the succeeding medium P2 in the target direction. Further, when the skew removing operation is performed, a part of the portion sent out by the overlapping operation of the succeeding medium P2 is supported by the lower path member 572 which is an example of the supporting member. The flap member 550 and the lower path member 572 move to a guide position that guides the movement path of the succeeding medium P2 and a retreat position that is an example of a non-guide position that does not guide the succeeding medium P2. Therefore, the frequency at which the rear end of the preceding medium P1 and the front end of the succeeding medium P2 are stacked in the correct stacking order can be increased, and the skew removing operation of the succeeding medium P2 can be easily avoided. Therefore, it is possible to suppress a decrease in print quality in the case where a mistake in the stacking order of the preceding medium P1 and the succeeding medium or correction of skew is insufficient.

  (6-2) The flap member 550, which is an example of the guide member, moves between the guide position and the non-guide position. Therefore, when the overlapping operation is performed, the subsequent medium P2 can be guided in the target direction by disposing the flap member 550 at the guiding position. As a result, the succeeding medium P2 can be stacked on the preceding medium P1 in an appropriate stacking order. In addition, by retracting the flap member 550 from the guide position to the retracted position (non-guide position) before the skew removing operation is performed, it becomes difficult for the succeeding medium P2 to buckle even if it hangs down.

  (6-3) When the stacking operation is started, the flap member 550 moves to the guide position before the fed subsequent medium P2 reaches the flap member 550, and guides the sending direction of the subsequent medium P2 in the target direction. . For this reason, the succeeding medium P2 sent in the target direction can be overlapped with a part of the preceding medium P1 in an appropriate overlapping order. Further, when the skew removing operation is performed, the flap member 550 becomes difficult to retract. Therefore, the skew removing operation of the succeeding medium P2 is performed appropriately.

  (6-4) The lower path member 572, which is an example of a movable support member, moves between the guide position and the retracted position (non-guide position). Therefore, when the overlapping operation is performed, the lower path member 572 is disposed at the non-guide position to suppress the rising of the rear end of the preceding medium P1, thereby preventing the rear end of the preceding medium P1 and the leading end of the succeeding medium P2. Can be overlapped in an appropriate stacking order. In addition, before the skew removing operation is performed, the lower path member 572 is disposed at the guide position, and a part of the portion of the subsequent medium P2 which is sent out by the overlapping operation is supported by the lower path member 572 disposed at the guide position. be able to. As a result, the skew of the succeeding medium P2 can be properly corrected. Therefore, the overlapping operation and the skew removing operation can be appropriately performed.

  (6-5) When the stacking operation is performed, the lower end member 572 moves to the retreat position (non-guide position), so that the rear end of the preceding medium P1 is less likely to float. As a result, the succeeding medium P2 can be overlaid on a part of the preceding medium P1 in an appropriate overlapping order. In addition, before the skew removing operation is performed, the lower path member 572 is disposed at the guide position, and the portion that is sent out and hangs down by the overlapping operation of the subsequent medium P2 is supported by the lower path member 572. The overlapping operation and the skew removing operation can be appropriately performed.

  (6-6) The control unit 50 controls the transport mechanism 24 to move the leading end of the subsequent medium P2 to the transport roller pair 33 as an example of a roller pair provided upstream of the printing unit 25 in the transport direction Y. A skew removal operation is performed by striking. The portion of the succeeding medium P2 that hangs down above the flap member 550 has an oblique surface shape that becomes lower toward the downstream side in the transport direction Y of the lower path member 572 disposed at the guide position before the skew removing operation is performed. It is supported by the guide surface 573 as an example of a support surface having the same. Therefore, the sagged portion of the succeeding medium is less likely to buckle, and the force generated when the succeeding medium is sent out to abut the leading end of the succeeding medium against the roller pair is transmitted to the leading end via the sagging portion, and an appropriate skew removing operation is performed. It can be carried out.

(2 of the sixth embodiment)
Next, a second embodiment of the sixth embodiment will be described with reference to FIG. This embodiment is an example in which a flap member 550 as a movable guide member and a fixed support member 57 are combined. As shown in FIG. 75, the flap member 550 is provided so as to be movable between a guide position and a retracted position, as in the first embodiment. That is, the guide member 55 is moved to the guide position when the first solenoid 91 is driven to be excited, and is moved to the retracted position (non-guide position) when the first solenoid 91 is driven to be demagnetized. The support member 57 is fixed in a protruding state at the position at the guide position in the first embodiment. In this example, since the support member 57 is of a fixed type, the second solenoid 92 in FIGS. 66 and 67 is not provided.

  In the present embodiment in which the support member 57 is fixed, in the flowchart shown in FIG. 74, the processing of steps S518 and S521 relating to driving of the support member 57 is omitted. Therefore, when the first sensor 51 detects the rear end Y1 of the preceding medium P1 that has deviated from the first nip position NP1 and switches from ON to OFF (YES in S515), the computer 62 switches the first solenoid 91 to ON. By excitation, the flap member 550 is moved and arranged from the retracted position shown by the two-dot chain line in FIG. 75 to the guide position shown by the solid line in FIG. 75 (S517).

  In this state shown in FIG. 75, the overlapping operation is performed (S519). According to the overlapping feeding method of the present embodiment, when starting the overlapping operation, the computer 62 excites the first solenoid 91 and moves and guides the guide member 55 from the retracted position to the guide position. At this time, the succeeding medium P2 sent out by the superposition operation is guided in the substantially horizontal direction intersecting the guide surface 56A for upper route guidance by the guide member 55 in a substantially horizontal posture, and is guided in the target direction. The succeeding medium P2 is fed through the upper path along the guide surface 56A. As a result, the leading end of the succeeding medium P2 can be superimposed on the trailing end of the preceding medium P1 as desired. Therefore, when the direction in which the leading end of the succeeding medium P2 overlaps the trailing end of the preceding medium P1 is reversed upside down, the first line of the succeeding medium P2 is printed in the trailing margin of the leading medium P1. Can be reduced. During this overlapping operation, the support member 57 is fixed so as to protrude to the guide position. However, the guide member 55 is retracted so as not to make much contact with the succeeding medium P2 and hangs obliquely downward. As compared with the configuration in which 55 is fixed in the horizontal posture, the amount of protrusion of the support member 57 is relatively small. For this reason, when the rear end of the preceding medium P1 rests on the guide surface 57A of the support member 57, the lifting of the rear end is relatively small.

  During the overlapping operation, the computer 62 acquires the leading end position Y2 of the subsequent medium P2 from the count value of the second counter 82, and when the acquired leading end position Y2 reaches the standby position Yw, drives the feed motor 41. Stop. As a result, the stacking operation is completed, and the succeeding medium P2 stops with its leading end located at the standby position Yw.

  When the stacking operation is completed, the computer 62 moves and arranges the flap member 550 from the guide position shown by the solid line in FIG. 75 to the retracted position (non-guide position) shown by the two-dot chain line in FIG. 75 by demagnetizing the first solenoid 91. I do. As a result, the succeeding medium P2 hanging from the nip position NP1 between the intermediate roller 30 and the driven roller 32 is guided by a path that draws a curved curve by being supported by the guide surface 57A of the support member 57.

  The computer 62 drives the feeding motor 41 during the printing operation of the last pass, and performs a skew removing operation in which the leading end of the succeeding medium P2 is brought into contact with the transport roller pair 33 whose rotation is stopped. At this time, the subsequent medium P2 is supported by the guide surface 57A of the support member 57 in a part of the way from the first nip position NP1 to the standby position Yw, so that the subsequent medium P2 moves from the first nip position NP1 to the standby position Yw. The path leading to the curved line takes a path that draws a curve, so that the force of pushing the succeeding medium P2 by the rotation of the intermediate roller 30 is reliably transmitted to the leading end Y2. As a result, the leading end of the preceding medium P1 is relatively strongly pressed against the transport roller pair 33, so that the skew is appropriately corrected by the skew removing operation.

(3 of the sixth embodiment)
Next, a third embodiment of the sixth embodiment will be described with reference to FIG. This embodiment is an example in which a fixed guide member 55 and a lower path member 572 which is an example of a movable support member are combined. As shown in FIG. 76, the guide member 55 is fixed in a horizontal posture at the time of the guide position in the first embodiment. The lower path member 572 is provided so as to be movable between a guide position indicated by a two-dot chain line in FIG. 76 and a retracted position indicated by a solid line in the same manner as in the sixth embodiment. That is, the lower path member 572 is moved to the retracted position when the computer 62 of the control unit 50 excites the second solenoid 92 (see FIGS. 66 and 67), and is not illustrated by demagnetizing the second solenoid 92. Is moved to the guide position by the urging force of the spring. In this example, since the guide member 55 is a fixed type, the first solenoid 91 in FIGS. 66 and 67 is not provided.

  In the present embodiment in which the guide member 55 is a fixed type, the processes of steps S517 and S520 are omitted in the flowchart shown in FIG. Therefore, when the rear end Y1 of the preceding medium P1 deviates from the first nip position NP1 and the first sensor 51 detects the rear end Y1 of the preceding medium P1 and switches from ON to OFF (Yes in S515), the computer 62. Excites the second solenoid 92 to move and move the lower path member 572 from the guide position shown by the two-dot chain line in FIG. 76 to the retracted position shown by the solid line in FIG. 76 (S518).

  The overlapping operation is performed in the state shown by the solid line in FIG. 76 (S519). According to the overlapping feeding method of the present embodiment, when starting the overlapping operation, the computer 62 excites the second solenoid 92 and moves and moves the lower path member 572 from the guide position to the retracted position. At this time, the succeeding medium P2 during the stacking operation is sent out from the guide member 55 fixed in a substantially horizontal posture in a substantially horizontal direction intersecting with the guide surface 56A for guiding the upper route, so that the oblique guide surface 56A is provided. Is transported along the route while keeping near the upper limit position. Since the lower path member 572 is retracted to the retracted position below during the overlapping operation, the rear end of the preceding medium P1 is less likely to float. As a result, the leading end of the succeeding medium P2 can be superimposed on the trailing end of the preceding medium P1 as desired. Therefore, when the order in which the leading end of the succeeding medium P2 is superimposed on the trailing end of the preceding medium P1 is upside down, the first line of the succeeding medium P2 is printed in the trailing margin of the preceding medium P1. Can be reduced.

  During the overlapping operation, the computer 62 acquires the leading end position Y2 of the subsequent medium P2 from the count value of the second counter 82, and when the acquired leading end position Y2 reaches the standby position Yw, drives the feed motor 41. Stop. As a result, the stacking operation is completed, and the succeeding medium P2 stops with its leading end located at the standby position Yw.

  When the overlapping operation of the succeeding medium P2 is completed, the computer 62 moves the lower path member 572 from the retracted position shown by the solid line in FIG. 76 to the guide position shown by the two-dot chain line in FIG. 76 by demagnetizing the second solenoid 92. Deploy. As a result, the succeeding medium P2 hanging down from the nip position NP1 between the intermediate roller 30 and the driven roller 32 is guided by a guide path 573 of the lower path member 572 raised to the guide position so as to draw a curved path. You.

  The computer 62 drives the feeding motor 41 during the printing operation of the last pass, and performs a skew removing operation in which the leading end of the succeeding medium P2 is brought into contact with the transport roller pair 33 whose rotation is stopped. At this time, the following medium P2 is supported by the guide surface 573 of the lower path member 572 and takes a path that draws a curve (for example, an S-shaped curve) in a part of the way from the first nip position NP1 to the standby position Yw. The force that pushes the succeeding medium P2 by the rotation of the intermediate roller 30 is reliably transmitted to the leading end Y2. As a result, the leading end of the preceding medium P1 is relatively strongly pressed against the transport roller pair 33, so that the skew is appropriately corrected by the skew removing operation.

(4 of the sixth embodiment)
Next, a fourth embodiment of the sixth embodiment will be described with reference to FIGS. This embodiment is an example in which the lower stack shown in FIG. 77 and the upper stack shown in FIG. 78 can be selected by selecting the medium guiding direction by the flap member 550, which is an example of a movable guide member. As shown in FIG. 77, the support member 57 for guiding the lower route is of a fixed type, and its guide surface 57A has a rear end portion that is a portion of the preceding medium P1 that is on the upstream side of the nip portion of the transport roller pair 33. And a support portion 575 for supporting the same at a predetermined height substantially equal to the nip position NP2, and a concave surface 576 that is largely recessed downward at a portion upstream of the support portion 575. The upstream side portion of the concave surface 576 is an inclined guide surface 57B.

  The configuration of the flap member 550 is the same as in the first and second embodiments of the sixth embodiment. The flap member 550 is rotatable about a rotation shaft 551 via an arm 552 within a predetermined angle range. The flap member 550 moves (rotates) between a guide position arranged by excitation of the first solenoid 91 as a power source thereof and a retracted position (non-guide position) arranged by demagnetization of the first solenoid 91. It is a configuration to do. The retracted position (non-guiding position) at the time of upper stacking is used as a guiding position at the time of lower stacking, and the guiding position at the time of upper stacking is used as a retracting position (non-guiding position) at the time of lower stacking. The points are different. That is, the flap member 550 can move between the first guide position for the upper stack and the second guide position for the lower stack as the guide position by rotating about the rotation shaft 551. Further, as the target direction, a first target direction for superimposition when guiding the feeding direction of the medium P when the flap member 550 is disposed at the first guide position, and the flap member 550 is disposed at the second guide position. There is a second target direction for lower stacking when guiding the feeding direction of the medium P when performed. In this example, since the support member 57 is of a fixed type, the second solenoid 92 in FIGS. 66 and 67 is not provided.

  When the computer 62 (see FIG. 66) of the control unit 50 excites the first solenoid 91, the flap member 550 is attached to the surface (printing surface) of the preceding medium P1 on the side facing the printing unit 25 (the printing surface). Are moved to and arranged at a first guide position at which an upper stack is possible. When the computer 62 demagnetizes the first solenoid 91, the flap member 550 causes the leading end of the succeeding medium P2 to be attached to the surface (non-printing surface) opposite to the surface facing the printing unit 25 with respect to the preceding medium P1. It is moved and arranged to a second guide position where it can be overlapped. In the present embodiment, the second guide position for the lower stack is the non-guide position when the upper stack is performed, and the first guide position for the upper stack is the non-guide position when the lower stack is performed. The position may be between the first guide position and the second guide position.

  Here, in the upper overlap, the leading end of the succeeding medium P2 is overlapped with at least a part of the trailing margin of the preceding medium P1. Also, when the succeeding medium P2 is superimposed on the preceding medium P1 in the superimposed state, the leading end position of the succeeding medium P2 is upstream of the image trailing end position of the leading medium P1 in the last pass of the leading medium P1. Side, the skew removing operation of the succeeding medium P2 is performed. According to this configuration, the skew removal operation of the succeeding medium P2 can be performed while continuously feeding the medium P2. On the other hand, in the lower overlapping, at least a part of the leading end margin of the succeeding medium P2 is overlapped with the trailing end of the preceding medium P1. Whether the margins are entirely or partially overlapped depends on the positional relationship between the preceding medium P1 and the succeeding medium P2 at the time of starting continuous feeding. At the time of lower stacking, when the succeeding medium P2 is superimposed on the lower side of the preceding medium P1 and the trailing end position of the preceding sheet is downstream of the image leading end position of the succeeding sheet at the last pass of the preceding medium P1, The skew removing operation of the medium P2 is performed. According to this configuration, the skew removing operation of the succeeding medium P2 can be performed while continuously feeding. It should be noted that, in the case of the upper overlapping, the printing operation of the last pass is basically started next to the continuous feeding, but in the case of the lower overlapping, the printing operation immediately before the start of the continuous feeding is not limited to the last pass.

  The computer 62 of the control unit 50 determines which of the upper and lower overlaps the overlap amount based on the information on the trailing margin (bottom margin) of the preceding medium P1 and the leading margin (top margin) of the succeeding medium P2. It is determined for each page whether it is possible to secure a large number of sheets or to carry out overlap continuous feeding, and one for which a larger amount of overlap can be secured or one for which overlap continuous feeding can be carried out is selected for each page. When selecting the upper stack, the computer 62 excites the first solenoid 91 to move and arrange the flap member 550 to the first guide position (guide position) shown in FIG. Send out in the target direction. When selecting the lower stack, the computer 62 demagnetizes the first solenoid 91 to move and arrange the flap member 550 to the second guide position shown in FIG. 78, and moves the subsequent medium P2 to the second target direction for the lower stack. Send to It should be noted that which of the upper stacking and the lower stacking can determine which one can secure a larger overlapping amount or can perform the overlap continuous feeding is determined not for each page but for each print job. It may be selected for each print job.

  At the time of the skew removing operation, the flap member 550 is disposed at the second guide position in common with the upper stack shown in FIG. 77 and the lower stack shown in FIG. It takes a path that draws an S-shaped curve supported by the surface 57B. For this reason, the force when the intermediate roller 30 sends out the succeeding medium P2 during the skew removing operation is reliably transmitted to the leading end thereof, and the leading end abuts on the transport roller pair 33 with an appropriate force, whereby the skew is appropriately corrected. .

  (6-7) The flap member 550, which is an example of a movable guide member, has a guide position for guiding the succeeding medium P2 in a target direction that can be superimposed on the surface facing the printing unit 25 with respect to the preceding medium P1. , The subsequent medium P2 can be moved to a non-guiding position where it can be superimposed on the surface facing the printing unit 25 with respect to the preceding medium P1 and on the opposite surface. Therefore, the succeeding medium P2 is overlapped on the surface of the preceding medium P1 facing the printing unit 25, and the succeeding medium P2 is overlapped on the surface of the preceding medium P1 opposite to the surface facing the printing unit 25. You can also.

  (6-8) The flap member 550 guides the succeeding medium P2 in the first target direction in which the succeeding medium P2 can be superimposed on the surface facing the printing unit 25 with respect to the preceding medium P1 in the first target direction. It moves to the second guide position for guiding the preceding medium P1 in the second target direction that can be superimposed on the surface facing the printing unit 25 and the surface on the opposite side. Therefore, the succeeding medium P2 is overlapped on the surface of the preceding medium P1 facing the printing unit 25, and the succeeding medium P2 is overlapped on the surface of the preceding medium P1 opposite to the surface facing the printing unit 25. You can also. Further, since the non-guiding position is the second guiding position or the position between the first guiding position and the second guiding position, before the skew removing operation is performed, the flap member 550 is moved to the second guiding position, Alternatively, it is arranged at a non-guide position that is a position between the first guide position and the second guide position. Thereby, the skew removal operation of the subsequent medium P2 is performed appropriately, and the skew of the subsequent medium P2 can be appropriately corrected.

(5 of the sixth embodiment)
Next, a fifth embodiment of the sixth embodiment will be described with reference to FIGS. In the present embodiment, a pair of movable guide members are provided, and the pair of guide members guide the medium P in different medium guiding directions, thereby selecting the upper layer shown in FIG. 79 and the lower layer shown in FIG. This is a possible example. As shown in FIG. 79, the guide surface 57A of the support member 57 supports the rear end of the preceding medium P1 on the upstream side of the transport roller pair 33 so as to be able to guide to the nip position NP2, the lower surface (back surface) thereof. It has a first support surface 577, a second support surface 578 located upstream and below the first support surface 577, and a slope 579 connecting the first support surface 577 and the second support surface 578. .

  The pair of guide members 555 and 556 are connected to a frame (not shown) so as to be rotatable around individual rotation shafts 553 and 554, and constitute a link mechanism that rotates in conjunction with each other while maintaining a parallel state. And a pair of arms. The pair of guide members 555 and 556 are excited by a first solenoid 91 (see FIGS. 66 and 67) which is a power source thereof, and a first guide position as an example of a guide position shown in FIG. 79 and a guide position shown in FIG. It is configured to move between a non-guide position (a retreat position) and a second guide position as an example.

  In other words, the guide members 555 and 556 rotate around the rotation shafts 553 and 554, and thereby the first guide position (guide position) for the upper stack and the second guide position (non-guide position for the lower stack). ). As the target direction, when the pair of guide members 555 and 556 are arranged at the first guide position, the first target direction for superimposing when guiding the feeding direction of the medium P and the pair of guide members 555 and 556 are used. There is a second target direction for lower stacking when guiding the feeding direction of the medium P when placed at the second guiding position. In this example, since the support member 57 is of a fixed type, the second solenoid 92 in FIGS. 66 and 67 is not provided.

  When the first solenoid 91 is excited, the guide members 555 and 556 cause the first medium P1 to overlap the leading end of the succeeding medium P2 on the surface (printing surface) of the preceding medium P1 facing the printing unit 25. It is moved to a first guide position (guide position) for guiding the succeeding medium P2 in the target direction. When the first solenoid 91 is demagnetized, the guide members 555 and 556 move the leading end of the succeeding medium P2 to the surface (non-printing surface) opposite to the surface facing the printing unit 25 with respect to the preceding medium P1. The second medium is moved to a second guide position (non-guide position) at which the succeeding medium P2 can be guided in the second target direction in which the lower medium can be overlapped. Also in the present embodiment, the second guide position for the lower layer is the non-guide position when the upper layer is overlapped, and the first guide position for the upper layer is the non-guide position when the lower layer is overlapped. The position may be between the first guide position and the second guide position.

  In the examples of FIGS. 79 and 80, the third sensor described in the fourth embodiment is provided for each of the upper and lower layers. That is, the third sensor 533 capable of detecting the succeeding medium P2 conveyed along the normal conveyance path along the guide surface 56A forming the upper path when the upper layer is selected, and the third sensor 533 when the lower layer is selected. A third sensor 534 capable of detecting the succeeding medium P2 conveyed along the normal conveyance path along the guide surface 57A (particularly, the second support surface 578) forming the lower path. The third sensors 533 and 534 are contact type sensors having levers 533A and 534A, and protrude from the guide surfaces 56A and 57A at the non-detection position. If the third sensor 533 detects (ON) during the stacking operation when the upper stacking is selected, the continuous stacking is executed, but if not (OFF), the double stacking is stopped. On the other hand, if the third sensor 534 detects (ON) during the overlapping operation when the lower overlap is selected, the overlapping continuous feeding is performed, but if not (OFF), the overlapping continuous feeding is stopped. In the fifth embodiment, the third sensors 533 and 534 are not essential.

  The computer 62 (see FIG. 66 and FIG. 67) of the control unit 50 controls the upper and lower overlaps based on information on the trailing edge margin length (bottom margin) of the preceding medium P1 and the leading edge margin length (top margin) of the succeeding medium P2. It is determined for each page which of the stacking can secure a larger stacking amount or can perform the continuous stacking. Then, based on the result of the determination, one for which a larger overlapping amount can be secured or one for which continuous overlapping can be performed is selected for each page. When the upper stacking is selected, the computer 62 excites the first solenoid 91 to move and arrange the guiding members 555 and 556 to the first guiding position (guiding position) shown in FIG. Send out in the first target direction. When the lower stack is selected, the computer 62 demagnetizes the first solenoid 91, moves the guide members 555 and 556 to the second guide position (non-guide position) shown in FIG. 80, and moves the subsequent medium P2 downward. It is sent out in the second target direction for stacking.

  At the time of the skew removing operation, the guide members 555 and 556 are commonly arranged at the second guide position in the case of the upper overlap in FIG. 79 and the lower overlap shown in FIG. That is, the non-guide position, which is the position of the guide members 555 and 556 during the skew removal operation, is also the second guide position. In addition, since the configuration does not use the large-diameter intermediate roller 30 (see FIG. 78), the difference in height between the first nip position NP1 and the guide surface 57A of the support member 57 is relatively small. In addition, buckling is less likely to occur at a location where the subsequent medium P2 has little droop and comes into contact with the guide surface 57A. Further, the succeeding medium P2 at the time of the skew removal operation is also supported by the first support surface 577 that extends substantially horizontally at a position near the transport roller pair 33 and at substantially the same height as the height of the nip portion.

  At the time of the skew removing operation, the force when the upstream transport roller pair 93 composed of the transport drive roller 93A and the transport driven roller 93B rotates to feed the subsequent medium P2 takes a path that draws a curve along the guide surface 57A. The skew is transmitted to the leading end of the succeeding medium P <b> 2, and the leading end is abutted against the transport roller pair 33 with an appropriate force, so that an appropriate skew removing operation is performed.

Therefore, the effect of (6-7) and the effect of (6-8) can be obtained in the same manner for 5 of the sixth embodiment.
The sixth embodiment can be changed to the following modes.

  As shown in FIG. 81, the lower path member 572, which is a movable support member, may be a slide type. As shown in FIG. 81, the fixed support member 57 is provided with a lower path member 572 which is an example of a movable support member slidable in a direction parallel to the transport direction Y with respect to the guide surface 57A. I have. A guide hole 57C that opens over a predetermined length is formed in the support member 57 at a position near the upstream side in the transport direction Y, and the lower path member 572 has a guide portion 57D that extends downward. Is slidable in the movement direction parallel to the transport direction Y along the guide hole 57C. The lower path member 572 moves from a guide position shown by a solid line in the same figure to a non-guide position shown by a two-dot chain line in the same figure by excitation of the power source, for example, the second solenoid 92, and by demagnetization of the second solenoid 92 Move from the non-guiding position to the guiding position. The support member 57 has a concave portion (not shown) at a position corresponding to the intermediate roller 30 in the width direction X, and can be moved to a position indicated by a two-dot chain line shown in FIG.

  In the case of the rotating lower path member 572 shown in FIG. 64, the lower path member 572 retracted to the non-guide position may block a part of the reversing path 40. On the other hand, if the lower path member 572 is of a sliding type as shown in FIG. 81, even when the lower path member 572 moves to the retracted position (non-guide position), a situation in which a part of the transport path such as the reversing path 40 is blocked is avoided. it can. If an electric motor is used as a power source, the height of the guide surface 573 supporting the succeeding medium P2 can be adjusted by continuously changing the slide position. In this case, the medium type (for example, paper type) and The succeeding medium P2 can be appropriately supported according to the medium size (paper size) and the like. The guide member may be a fixed type guide member 55 instead of the movable flap member 550.

  The lower path member 572, which is an example of a movable support member, may be configured to slide in a direction parallel to the direction of gravity Z (height direction). Further, in this configuration, if the height of the guide surface 573 can be adjusted by changing the slide position when supporting the succeeding medium P2 by using an electric motor as a power source, the succeeding medium P2 hangs down from the nip position NP1. The middle part can be appropriately supported according to the medium type, the medium size, and the like.

  In the sixth embodiment, the flap member 550, which is an example of a movable guide member, is mechanically utilizing the power of the feed motor 41 instead of using a solenoid 91 or a dedicated electric motor as a power source. It may be driven. The mechanical drive mechanism of the flap member 550 operates, for example, when the operated portion disposed at a position operated by the tip of the succeeding medium P2 that has passed the first nip position NP1 during the overlapping operation, and the operated portion is operated. A one-time clutch connected so as to transmit the power of the feed motor 41 to the flap member 550; When the operated portion is operated, the power of the feed motor 41 is transmitted to the flap member 550 via the one-time clutch by connecting the one-time clutch, and the flap member 550 moves from the retracted position to the guide position. I do. The one-time clutch has a cam mechanism operated by the power transmitted by the connection. When the operation of the cam mechanism is started, the flap member 550 is moved from the retracted position to the guide position, and held at the guide position for a predetermined rotation amount until the overlapping operation is completed. When the user moves to the evacuation position and returns to the evacuation position, the connection of the clutch is released by the cam mechanism. According to this configuration, without using an actuator such as the solenoid 91 or the electric motor, the flap member 550 is disposed at the guide position only for a necessary period during which the overlapping operation is performed, and is not operated during an unnecessary period when the overlapping operation is not performed. Can be placed at the guidance position.

  In the sixth embodiment, the lower path member 572, which is an example of a movable support member, uses a mechanical power source by using the power of the feed motor 41 instead of using a solenoid 91 or a dedicated electric motor as a power source. May be driven. The mechanical drive mechanism of the lower path member 572 operates, for example, when the operated part is operated at the position operated by the leading end of the succeeding medium P2 that has passed the first nip position NP1 during the overlapping operation, and the operated part is operated. And a one-time clutch that is connected to be able to transmit the power of the feed motor 41 to the lower path member 572. When the operated portion is operated, the power of the feed motor 41 is transmitted to the flap member 550 via the one-time clutch by connecting the one-time clutch, and the flap member 550 moves from the retracted position to the guide position. I do. The one-time clutch has a cam mechanism operated by the power transmitted by the connection. When the operation of the cam mechanism is started, the flap member 550 is moved from the retracted position to the guide position by the power transmitted via the cam mechanism, and is held at the guide position for a predetermined rotation amount until the overlapping operation is completed. Thereafter, when the flap member 550 is moved to the original evacuation position and returned to the evacuation position, the connection of the clutch is released by the cam mechanism. According to this configuration, without using an actuator such as the solenoid 91 or the electric motor, the flap member 550 is disposed at the guide position only for a necessary period during which the overlapping operation is performed, and is not operated during an unnecessary period when the overlapping operation is not performed. Can be placed at the guidance position.

Further, the first to sixth embodiments can be changed to the following forms.
In each of the above embodiments, the process of determining whether or not the superimposable condition is satisfied may be performed after the superimposition operation. For example, before the start of the printing operation of the last pass or before reaching the determination position, the overlapping operation is started, and whether or not the overlapping operation is completed in a period from the stop at the standby position Yw to the start of the printing operation of the last pass. Is determined, and a determination is made as to whether the overlapping condition is satisfied. Then, when both conditions are satisfied, the control unit 50 performs the overlap continuous feeding.

  In the above embodiments, the timing for starting the continuous feeding is not limited to after the end of the printing operation of the last line. Overlapping continuous feeding may be started at the end of the printing operation of the line before or the line before the printing operation of the last line. The trailing margin length of the preceding medium P1 is known, and the skew removing operation is performed at the time of the printing operation in which the leading edge of the succeeding medium P2 is overlapped only with the trailing margin area of the preceding medium P1 for the next transport operation. It is only necessary to perform continuous feeding at. In these cases, after the start of the continuous feeding, the transport operation is performed by the continuous feeding until the preceding medium P1 reaches the position of the printing operation of the last line, and after the printing operation of the last line is completed, the printing of the succeeding medium P2 is started. Continuous feeding is performed to the position. According to these configurations, a larger overlapping amount can be ensured, which can contribute to further improvement in the printing throughput.

  In each of the above embodiments, the skew removal operation is not limited to the printing operation (during the last pass) of the printing line (for example, the last line) immediately before performing the overlap continuous feeding. The skew removing operation may be performed during a printing operation (during a pass) one or more times before a printing line (for example, the last line) in which continuous feeding is performed. In short, it suffices that the skew removing operation be completed before the printing operation of the last line.

  In the above embodiments, the registration roller driven by the feed motor 41 at a position upstream of the feed roller pair 33 in the feed direction Y and connected to the power transmission path of the feed motor 41 via a clutch. A pair may be provided, and the skew removal may be performed in advance by abutting the leading end of the succeeding medium against the registration roller pair in the rotation stopped state. In this case, since the succeeding medium P2 which has been skewed in advance can be arranged at the standby position Yw, if the succeeding medium P2 can be stopped at the standby position Yw by the end of the last pass, it is possible to carry out continuous feeding. Further, this configuration may be applied to a line printer. In the line printer, printing proceeds while the printing unit prints one line (one band) at a time on the preceding medium P1 conveyed at a constant speed. The rotation of the registration roller is temporarily stopped in a state where the conveyance of the preceding medium P1 is not hindered, and the leading end of the registration roller pair is stopped so as to skew the subsequent medium P2. Thereafter, at the timing when the leading end of the succeeding medium P2 overlaps only the trailing margin area of the preceding medium P1, the conveyance of the succeeding medium P2 is started by the rotation of the pair of registration rollers, thereby performing continuous feeding. In the case of lower stacking, the conveyance of the succeeding medium P2 is started by rotating the pair of registration rollers at a timing when only the leading end margin area of the succeeding medium P2 overlaps the rear end of the preceding medium P1. Perform continuous feeding.

  A skew correction device that corrects the skew of the medium P by applying a guide from both sides to two sides parallel to the conveyance direction Y of the medium P is provided, and performs a skew removal operation by abutting the conveyance roller pair 33 or the registration roller pair. There may be no configuration. For example, in a line printer, if this skew correction device is used, it is not necessary to temporarily stop the preceding medium P1 for the skew removing operation of the succeeding medium P2, and the printing throughput can be further improved.

  In the first to fifth embodiments showing only an example of the upper stack, in the stacking operation, the leading end of the succeeding medium is fed below the trailing end of the preceding medium, so that the stacking order is upside down. Stacking may be adopted. In this case, the upper conveyance guide (for example, the guide surface 56A) that guides the preceding medium P1 in a state where a gap is formed below the rear end of the preceding medium, and the subsequent conveyance guide enters the gap below the rear end of the preceding medium P1. It is preferable to provide a lower conveyance guide (for example, guide surface 57A) for guiding the succeeding medium P2 so as to feed the leading end of the medium P2.

  The medium loading section is not limited to the cassette, and may be a feed tray. For example, in FIG. 3, a feed passage extending obliquely downstream and downward between the intermediate roller 30 and the second driven roller 32, and an opening and closing provided on the upstream (right side in FIG. 3) side of the housing 153. A feed tray is provided that is exposed when the cover is opened. Then, the medium P placed on the feeding tray may be fed through the feeding path and the first and second nip positions NP1 and NP2.

The printing device is not limited to a serial printer, but may be a lateral printer in which a printing unit moves in two directions, a main scanning direction and a sub-scanning direction, and prints on a medium.
Although two driven rollers capable of nipping the medium P are arranged on the outer periphery of the intermediate roller 30, at least one driven roller may be arranged. For example, one driven roller may be disposed, or three or four or more driven rollers may be disposed.

  The processing performed by the control unit 50 is not limited to the configuration realized by software by the computer 62 that executes the program, but may be realized by hardware using an electronic circuit such as an FPGA (field-programmable gate array) or an ASIC. It may be realized by cooperation between software and hardware.

-The printing device may be a dot impact system or an electrophotographic system in addition to the inkjet system. Further, the printing apparatus is not provided in the multifunction peripheral, but may be a dedicated printing apparatus.
The medium is not limited to paper, and may be a resin film or sheet, a composite film of resin and metal (laminated film), a woven fabric, a nonwoven fabric, a metal foil, a metal film, a ceramic sheet, or the like.

  -The printing device is not limited to a printing device that performs printing on a planar medium such as paper, but also a printing device for forming a three-dimensional three-dimensional object that forms a three-dimensional three-dimensional object by ejecting resin droplets by an inkjet method, for example. Good. In this case, the medium may be a mount or a sheet-like substrate from which the resin droplets are to be discharged.

  In the first to sixth embodiments, all may be combined, at least two may be combined, or only one may be implemented, as long as there is no contradiction in the configuration.

  DESCRIPTION OF SYMBOLS 11 ... Multifunction machine, 12 ... Printing apparatus, 21 and 22 ... Cassette as an example of a media loading part, 24 ... Transport mechanism which comprises an example of a transport part, 25 ... Printing part, 28 ... Feeding roller, 30 ... 1st An intermediate roller as an example of a roller, 31... A first driven roller, 32... A second driven roller, 33... A conveying roller pair as an example of a second roller, 36. A carriage, 38. , A transport motor, which constitutes an example of a transport unit, 48, a carriage motor, 50, a control unit, 51, a first sensor, 52, a second sensor, 62, a computer, 63, a head drive circuit , 64-66: motor drive circuit; 71: CPU; 72: ASIC; 75: nonvolatile memory as an example of a storage unit; 81: first counter; 2 counter, 84: a fourth sensor as an example of a position sensor, 85, a fifth sensor as an example of a gap sensor, 86, an ultrasonic sensor as an example of a position sensor, 87, a lever sensor as an example of a position sensor , 88: optical sensor as an example of a gap sensor, P: medium, P1: preceding medium, Y1: rear end position (rear end) of the preceding medium, P2: succeeding medium, Y2: leading end position (front end) of the succeeding medium , Yw: Standby position as an example of a predetermined position, LA: Overlapping range, YL: Lower limit position, YU: Upper limit position, SD: Distance as an example of first drive amount (distance between sensors), FD: Second drive Transport distance as an example of the amount, ND: distance as an example of the third drive amount, X: scanning direction (width direction), Y: transport direction.

Claims (6)

A transport unit having a first roller that transports the medium and a second roller that is located downstream of the transport path of the medium with respect to the first roller;
A printing unit that prints on the medium transported by the transport unit,
A first sensor that detects that the leading end of the medium has separated from the first roller;
A second sensor provided at a position between the first sensor and the second roller in the transport path;
A control unit that controls the transport unit and the printing unit,
The control unit measures a first drive amount from a detection position where the first sensor detects the medium conveyed by the conveyance unit to a detection position where the second sensor detects the medium. A second driving amount for driving the transport unit from the detection position of the first sensor to a predetermined position based on the first driving amount.   The printing apparatus according to claim 1, wherein the predetermined position is set at a position between the second sensor and a nip position of the second roller at which the medium is nipped. The control unit is configured to feed a subsequent medium that is a medium that is transported next to a preceding medium that is a medium that is transported earlier by the transport unit at a feed speed higher than the transport speed of the preceding medium. An overlapping operation for partially overlapping the preceding medium; and an overlapping sequence for conveying the preceding medium and the succeeding medium together after the printing of the preceding medium is completed until the succeeding medium reaches a printing start position while maintaining the overlapping state. And send
The printing apparatus according to claim 1, wherein the predetermined position is a standby position where the succeeding medium is made to wait until the overlapping continuous feeding is started after the completion of the overlapping operation. A storage unit that stores a third drive amount from a detection position of the second sensor to a position at which the second roller nips the medium;
The controller, when performing continuous printing on a plurality of the media, controls the first drive amount from the detection position of the first sensor to the detection position of the second sensor when conveying the first sheet of the medium. The printing apparatus according to claim 2, wherein the second drive amount is measured based on the first drive amount and the third drive amount. 5. Further comprising a position sensor for detecting that the medium has reached the predetermined position,
The control unit causes the transport unit to transport a medium subsequent to the medium at a first transport speed to a set position upstream of the predetermined position based on the corrected second drive amount,
The medium is conveyed from the set position to the predetermined position at a second conveyance speed lower than the first conveyance speed, and the driving of the conveyance unit is stopped at a position where the position sensor detects the medium. The printing device according to claim 1. A gap sensor that can detect a gap between the preceding medium and the succeeding medium when the overlapping operation of the succeeding medium is completed,
The control unit, after stopping the subsequent medium at the standby position, if the gap sensor detects a gap between the preceding medium and the succeeding medium, stops the overlap continuous feeding. The printing apparatus according to claim 3, wherein

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