JP5842493B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that determines the position of an image recording range with respect to a sheet when performing image recording by conveying the sheet placed on a tray.

  2. Description of the Related Art Conventionally, there has been provided an ink jet recording apparatus that performs image recording by discharging a sheet placed on a tray by a feeding unit and transporting the sheet by a transport roller, and ejecting ink droplets from the recording head onto the sheet that has reached the platen. Yes. This type of ink jet recording apparatus is provided with a print head (recording head) that can reciprocate in the sheet width direction. Some print heads are provided with a paper width sensor for detecting the paper size (see Patent Document 1).

  In the ink jet recording apparatus, for example, when the sheet is placed on a tray, the sheet in the width direction is not placed at an appropriate position, or the sheet is skewed during conveyance, so that the sheet paper on the platen The position in the width direction may be different for each sheet. Then, the position of the image recording range differs for each sheet in the paper width direction, and there is a possibility that an image is not recorded at an appropriate position on the paper. Therefore, it is conceivable to detect the position of the sheet in the sheet width direction on the platen using the sheet width sensor described in Patent Document 1, and determine the position of the image recording range in the sheet width direction based on the detection result. . The image forming apparatus described in Patent Document 1 moves the print head by determining the image recording range based on the paper size detected by the paper width sensor.

JP 2004-224521 A

  In the above-described ink jet recording apparatus, when the position in the width direction of the sheet is detected, it is executed so as to cross both ends of the sheet in the width direction on the platen. The operation of detecting the position in the width direction of the sheet is an operation different from the operation of recording an image. In this case, the image recording time from when the sheet placed on the tray is sent out until the image recording on the sent sheet is completed is detected in addition to the time only for recording the image, and the position in the width direction is detected. It takes time to operate. Therefore, the image recording time may be longer than necessary.

  Therefore, in the image forming apparatus described in Patent Document 1, for example, the sheet size is detected only for a sheet on which an image is first recorded after the power is turned on. Then, on the paper on which an image is recorded thereafter, the paper size is not detected on the assumption that the paper size is not changed. In other words, the sheet width sensor detects the position of only the first sheet after the power is turned on, and for the second and subsequent sheets, the detection result of the sheet width sensor on the first sheet is used. Determine the position of the image recording range. Then, it is possible to shorten the image recording time while suppressing a decrease in position accuracy of the image recording range.

  By the way, some inkjet recording apparatuses are provided in a main body housing so that the tray can be moved so that sheets can be easily supplied to the tray. When the tray is moved, the position of the sheet in the tray changes due to the vibration of the tray during the movement. In this case, when a sheet is supplied to the tray, the tendency of the positional deviation of the sheet in the sheet width direction on the platen changes before and after the sheet supply, that is, before and after the tray is moved. Therefore, the position accuracy of the image recording range cannot be kept high.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to shorten the image recording time and to maintain high position accuracy of the image recording range regardless of whether the tray is moved. It is to provide means.

  (1) In the ink jet recording apparatus of the present invention, a feeding unit that abuts on a sheet and feeds the conveyance path, a stacked sheet is placed, and the uppermost sheet can be fed by the feeding unit. A tray in which a sheet at the first position and the uppermost position can be moved to a second position where the sheet cannot be fed by the feeding unit, a conveyance roller that conveys the sheet sent to the conveyance path by the feeding unit, and the conveyance A platen provided with a support surface for supporting a sheet conveyed by the roller, and reciprocally movable in a first direction orthogonal to the sheet conveyance direction by the conveyance roller, and the platen is conveyed relative to the sheet conveyed A carriage disposed opposite to the platen, a recording head mounted on the carriage and ejecting ink droplets onto a sheet supported by the support surface, First detection means for detecting an end of the sheet supported on the support surface in the first direction in the movement in the first direction, and the tray has moved from the second position to the first position; or Second detection means for detecting movement from the first position to the second position, storage means for storing the position of the edge detected by the first detection means, and counting the number of sheets on which images are recorded Counting means, a reset means for resetting the count value of the counting means when detected by the second detecting means, and after the resetting of the count value by the reset means, the count value of the counting means is less than a first threshold value On the condition that the first detection means detects the end, stores the detected end in the storage means, and based on the position of the end. The image recording range in the first direction is determined, and on the condition that the count value of the counting unit is equal to or greater than the first threshold value, the first detection unit does not detect the end and stores the edge. Control means for executing a first control for determining the image recording range based on the position of the end stored in the means, and the recording head determines the image recording determined by the control means. Ink droplets are ejected according to the range.

  The fact that the tray has been moved from the second position to the first position is detected by the second detection means. The reset unit resets the count value of the counter unit when the second detection unit detects that the tray has been moved to the first position. This count value is used for control of the control means. When recording the image on the sheet, the control unit causes the first detection unit to detect the end of the sheet and store the image in the storage unit if the count value of the count unit is less than the first threshold value. The control means determines the image recording range in the first direction based on the position of the edge of the sheet stored in the storage means. When the count value of the counting means is equal to or greater than the first threshold, the control means does not detect the edge of the sheet by the first detection means, and based on the position of the sheet edge stored in the storage means, The image recording range in one direction is determined. Since the position of the edge of the sheet is detected only for the number of sheets determined by the first threshold, the image recording time is shortened. Further, since the position of the end of the sheet is detected every time the tray is moved, the position accuracy of the image recording range is kept high regardless of whether or not the tray is moved.

  (2) The ink jet recording apparatus of the present invention further includes third detection means for detecting the thickness of the sheet layer laminated on the tray, and the reset means detects the thickness detected by the third detection means. The count value of the counting means may be reset on the condition that becomes the second threshold value.

  Even if the image recording on the sheet progresses and the thickness of the sheet layer becomes thin and the tendency of the sheet position shift immediately after replenishment, the position accuracy of the image recording range can be kept high.

  (3) The tray further includes an inclined surface that is inclined and rises from the mounting surface on which the sheet is mounted, and the feeding unit is rotatable about the support shaft and the support shaft. And an arm supported by the arm and rotatably provided at the pivoting tip of the arm so as to be able to contact the uppermost sheet. A first sensor for detecting a leading edge of the sheet being fed by the feeding roller in the transport direction; and a third sensor that is disposed in the transport path. And an encoder for detecting the rotation amount of the feeding roller.

  The sheet at the uppermost position of the sheet layer is fed out to the conveyance path by the feeding roller of the feeding unit. The fed sheet is directed to the first sensor while being in sliding contact with the inclined surface. Therefore, the thicker the layer of the stacked sheets, the shorter the transport distance to the first sensor. The conveyance distance to the first sensor is detected by an encoder.

  (4) The tray further includes an inclined surface that is inclined and rises from the mounting surface on which the sheet is mounted, and the feeding unit is rotatable about the support shaft and the support shaft. And an arm supported by the arm and rotatably provided at a rotating tip of the arm so as to be able to come into contact with the uppermost sheet. By rotating in contact with the sheet, the sheet is fed to the inclined surface side. The third detecting means is rotatably provided on the upper side of the tray at the first position, and contacts the upper surface of the sheet at the uppermost position of the sheet layer. You may have a contact piece and the 2nd sensor which detects the rotation position of the said contact piece. With a simple configuration, the thickness of the sheet layer can be detected.

  (5) The reset means may reset the count value when the count value of the count means reaches a third threshold value.

  Even if the image recording on the sheet progresses and the thickness of the sheet layer becomes thin and the tendency of the sheet position shift immediately after replenishment, the position accuracy of the image recording range can be kept high.

  (6) The control means includes a first recording mode for performing the first control, and a second recording mode for causing the first detecting means to detect the edge of the sheet regardless of the count value of the counting means. , May be included.

  The present invention focuses on the fact that the tendency of the positional deviation of the sheet on the platen changes each time the tray is moved, and detects the edge position of the sheet only for the number of sheets determined by the first threshold. As a result, the image recording time can be shortened, and the position of the sheet edge is detected every time the tray is moved, so that the position accuracy of the image recording range can be kept high regardless of whether or not the tray is moved. As a result, an easy-to-use ink jet recording apparatus in which the image recording time and the image recording accuracy are balanced is realized.

1 is a perspective view of an inkjet recording apparatus 10. FIG. 2 is a schematic longitudinal sectional view of the inside of a printer unit 11. FIG. 2 is a perspective view of a main tray 21. FIG. 3 is a schematic bottom view of the recording head 51. FIG. (A) is a perspective view of the first rotary encoder 120, and (B) is a perspective view of the registration sensor 150. 3 is a plan view of a part of the printer unit 11. FIG. 3 is a block diagram for explaining control by a control unit 100. FIG. 3 is a flowchart for explaining control by a control unit 100. FIG. 10 is a block diagram of a first modification. FIG. 10 is a schematic longitudinal sectional view of the inside of a printer unit 11 according to Modification 2.

  Hereinafter, embodiments of the present invention will be described. The embodiment described below is an example of the present invention, and the embodiment may be appropriately changed without departing from the gist of the present invention.

  In the following description, as shown in FIG. 1, the vertical direction 7 is defined with reference to a state where the inkjet recording apparatus 10 is installed to be usable. Further, the front-rear direction 8 is defined with the side on which the operation unit 17 is provided as the front (front) side of the inkjet recording apparatus 10. Further, a left-right direction 9 is defined when the ink jet recording apparatus 10 is viewed from the front side.

[Outline of Inkjet Recording Apparatus 10]
As shown in FIG. 1, the inkjet recording apparatus 10 is recorded on a document (not shown) and a printer unit 11 that records an image on a sheet 6 (FIG. 2) such as recording paper, glossy paper, or a postcard. A scanner unit 12 that captures the captured image, and can execute printing, scanning, copying, and the like. Since the scanner unit 12 has an arbitrary configuration, the printer unit 11 will be described below.

[Outline of Printer 11]
The printer unit 11 includes a main body 13 and a paper feed cassette 20 that is detachably attached to the main body 13. As shown in FIG. 2, the main body 13 further includes a feeding unit 40 that feeds the sheet 6 placed in the sheet feeding cassette 20 to the conveyance path 30, a pair of rollers 34 and 37 that convey the sheet 6, and the sheet 6. Are provided with a recording head 51 for recording an image and a control board 18. The control board 18 is electrically connected to an external device such as the operation unit 17 (FIG. 1) or a personal computer by a cable (not shown). A microcomputer (not shown) that implements the control unit 100 (FIG. 7) is mounted on the control board 18. When a printing instruction is input from the operation unit 17 or an external device via the cable, the control unit 100 drives the ASF motor 61 and the like (FIG. 7) to record an image on the sheet 6. Hereinafter, each configuration of the printer unit 11 will be described.

[Main body casing 14]
As shown in FIG. 1, an insertion / extraction port 15 for insertion / extraction of the paper feed cassette 20 is formed in the main body casing 14 of the main body 13 on the front side in the front-rear direction 8. A guide rail (not shown) is provided behind the insertion / extraction opening 15. The paper feed cassette 20 is supported by the guide rail so as to be slidable in the front-rear direction 8. The paper feed cassette 20 is detached from the main body 13 by sliding in the front-rear direction 8 through the insertion / extraction opening 15.

  An opening / closing lid 16 is rotatably provided on the front side of the main body casing 14. A cartridge mounting portion 19 shown in FIG. 6 is provided on the back side of the opening / closing lid 16. Four ink cartridges 59 for supplying ink to the recording head 51 are mounted on the cartridge mounting portion 19.

[Paper cassette 20]
As shown in FIG. 1, the paper feed cassette 20 is disposed at the lower part of the main body housing 14 and is supported by a guide rail (not shown) provided in the main body housing 14 so as to be slidable in the front-rear direction 8. ing. The paper feed cassette 20 is attached to and detached from the main body 13 through the insertion / extraction opening 15 of the main body housing 14. In the following, the position of FIG. 1 attached to the main body 13 is defined as a first position (an example of the first position of the present invention), and the upstream side in the mounting direction of the paper feed cassette 20 relative to the first position is a second position (the main position). It will be described as an example of the second position of the invention. The sheet 6 (FIG. 2) is sent out from the paper feed cassette 20 in the first position to the transport path 30 (FIG. 2) by the feeding unit 40 (FIG. 2).

  As shown in FIG. 2, the paper feed cassette 20 includes a main tray 21 (an example of a tray according to the present invention) that holds sheets 6 before image recording, a paper discharge tray 29 that receives sheets 6 after image recording, It has.

[Main tray 21]
As shown in FIG. 3, the main tray 21 includes a bottom plate 22, a pair of left and right side plates 23 and 24, a front plate 25, and an inclined plate 26. The pair of left and right side plates 23, 24 protrude upward from both ends in the left-right direction 9 of the bottom plate 22. The front plate 25 protrudes upward from the front end portion of the bottom plate 22 in the front-rear direction 8. The side plates 23 and 24 have bearings (not shown) that rotatably support a rotation shaft (not shown) provided on the paper discharge tray 29 (FIG. 2). That is, the main tray 21 supports the paper discharge tray 29 so that the side plates 23 and 24 can rotate. The paper discharge tray 29 is rotated upward by the user when the sheet 6 is supplied to the main tray 21. As shown in FIG. 2, the closed paper discharge tray 29 is supported by the upper surfaces of the side plates 23 and 24 and the front plate 25.

  As shown in FIG. 2, the bottom plate 22 has a rectangular plate-like outer shape whose thickness is the up-down direction 7. Various sizes of sheets 6 such as A4 size, B5 size, and legal size are placed on the placement surface 22A that is the upper surface of the bottom plate 22. Therefore, the side guide mechanism 70 and the rear guide 80 are provided on the bottom plate 22. The side guide mechanism 70 positions the sheets 6 of various sizes placed on the bottom plate 22 by center alignment and suppresses the skew of the sheets 6 sent out by a feeding unit 40 described later. Center alignment means alignment that aligns the center of the sheet 6 in the left-right direction 9 with the center of the bottom plate 22 in the left-right direction 9. On the other hand, the rear guide 80 is for bringing the leading end (rear end in the front-rear direction 8) in the feeding direction of the seat 6 into contact with or close to the inclined plate 26. The side guide mechanism 70 and the rear guide 80 will be described later.

  A through hole 67 in which the rear guide 80 is disposed is formed in the bottom plate 22. Specifically, the through hole 67 is formed to extend in the front-rear direction 8 so that the rear guide 80 can move in the front-rear direction 8. Further, the through hole 67 (FIG. 3) is provided at the central portion in the left-right direction 9 of the bottom plate 22 so that the rear guide 80 can come into contact with any size of the seat 6.

  As shown in FIG. 3, a plurality of first grooves 68 that are recessed from the placement surface 22 </ b> A are provided on both sides of the through hole 67 in the left-right direction 9. The plurality of first grooves 68 extend in the front-rear direction 8 and are provided adjacent to each other in the left-right direction 9. The rear guide 80 is locked to the bottom plate 22 by selectively fitting a locked projection (not shown) of the rear guide 80 described later into one of the plurality of first grooves 68.

  A plurality of second grooves 69 that are recessed from the mounting surface 22 </ b> A are provided in the bottom plate 22. The plurality of second grooves 69 extend in the left-right direction 9 and are provided adjacent to each other in the front-rear direction 8. A locked protrusion (not shown) provided on a guide member 71 described later selectively fits into one of the plurality of second grooves 69, whereby the guide member 71 is locked to the bottom plate 22.

[Side guide mechanism 70]
As shown in FIG. 3, the side guide mechanism 70 moves the pair of left and right guide members 71 and 72 supported by the bottom plate 22 so as to be slidable in the left and right direction 9 and the pair of guide members 71 and 72 in conjunction with each other. And a pinion gear 73.

  The seat 6 (FIG. 2) is brought into contact with or close to the inclined plate 26 by a rear guide 80 described later. Therefore, the pair of guide members 71 and 72 are disposed at the rear portion of the bottom plate 22 in the front-rear direction 8 so that the seat 6 of any size can be positioned with respect to the inclined plate 26.

  The right guide member 71 is disposed on the right side of the bottom plate 22 in the left-right direction 9. The guide member 71 includes a support portion 74 placed on the bottom plate 22, a guide rib portion 75 protruding upward from the right end portion of the support portion 74, and a rack gear 76 extending from the support portion 74 toward the left. ing. The rack gear 76 meshes with the pinion gear 73 on the front side of the pinion gear 73 described later.

  The support portion 74 is provided with an elastic piece 77 that can be elastically deformed in the vertical direction 7. From the right end portion of the elastic piece 77 in the left-right direction 9, a knob piece 78 picked up by the user is projected upward. Further, a locked projection (not shown) that fits in the second groove 69 of the bottom plate 22 protrudes downward from the lower surface of the elastic piece 77. The guide protrusion 71 is locked to the bottom plate 22 by selectively fitting the locked protrusion into one of the plurality of second grooves 69.

  The left guide member 72 is disposed on the left side of the bottom plate 22 in the left-right direction 9. The guide member 72 includes a support portion 46, a guide rib portion 47, and a rack gear 48. The guide member 72 has a shape that is substantially symmetrical to the guide member 71 except that the elastic piece 77 and the knob piece 78 are not provided. The rack gear 48 of the guide member 72 meshes with the pinion gear 73 on the rear side of the pinion gear 73.

  The pinion gear 73 is arranged at the center of the bottom plate 22 in the left-right direction 9 with the central axis line along the up-down direction 7. The pinion gear 73 is meshed with the rack gear 76 of the guide member 71 on the front side in the front-rear direction 8 and meshed with the rack gear 48 of the guide member 72 on the rear side.

  After placing the sheet 6 (FIG. 2) on the bottom plate 22, the user holds the guide rib portion 75 and the knob piece 78 to bend the elastic piece 77. Next, the above-mentioned locked protrusion (not shown) is removed from the second groove 69, and the guide member 71 is slid leftward in the left-right direction 9. As a result, the support portion 74 sinks under the right end portion of the seat 6 in the left-right direction 9, and the guide rib portion 75 comes into contact with the right end of the seat 6. When the guide member 71 is slid leftward, the pinion gear 73 is rotated and the guide member 72 is slid rightward. As a result, the support portion 46 sinks under the left end portion of the seat 6 in the left-right direction 9, and the guide rib portion 47 comes into contact with the left end of the seat 6. When the user removes his / her finger from the guide rib portion 75 and the knob piece 78, the elastic piece 77 that has been bent returns to its original shape, and the locked protrusion provided on the elastic piece 77 fits into the second groove 69, thereby guiding the guide member 71. Is locked to the bottom plate 22 of the main tray 21. In this way, the sheets 6 of various sizes placed on the bottom plate 22 are positioned by center alignment by the side guide mechanism 70. Further, when the sheet 6 is fed rearward in the front-rear direction 8 by a feeding unit 40 which will be described later, the sheet 6 is fed in a state where both ends of the sheet 6 in the left-right direction 9 are in contact with the guide rib portions 75, 47. Thereby, the skew of the sheet 6 is suppressed.

[Rear guide 80]
As shown in FIG. 2, the rear guide 80 includes a base portion 81 inserted through the through hole 67 of the bottom plate 22 of the main tray 21. Guide grooves (not shown) in which the side walls of the through holes 67 in the left-right direction 9 are fitted are provided on both left and right sides of the base 81. The rear guide 80 is supported by the bottom plate 22 so as to be slidable in the front-rear direction 8 in the guide groove.

  As shown in FIGS. 2 and 3, a contact piece 82 that contacts the front end of the seat 6 in the front-rear direction 8 protrudes from the upper surface of the base 81. A knob 83 that is picked by the user together with the contact piece 82 is disposed on the front side of the contact piece 82 in the front-rear direction 8. The knob 83 is connected to the base 81 by an elastic piece (not shown). A locking projection (not shown) that fits in the first groove 68 provided on the bottom plate 22 protrudes downward from the lower surface of the elastic piece. When the knob 83 is picked by the user, the elastic piece is elastically deformed, and the locked protrusion is detached from the first groove 68. Then, the rear guide 80 can slide in the front-rear direction 8.

  After placing the sheet 6 on the bottom plate 22, the user can slide the rear guide 80 by gripping the contact piece 82 and the knob 83. Next, the rear guide 80 is slid backward in the front-rear direction 8. As a result, the base portion 81 sinks under the front end portion of the seat 6 in the front-rear direction 8, and the contact piece 82 contacts the front end of the seat 6 to push the seat 6 rearward in the front-rear direction 8. The seat 6 pushed backward is brought into contact with or brought close to the inclined plate 26 at the rear end in the front-rear direction 8. When the user removes his / her finger from the abutting piece 82 and the picking piece 83, the bent elastic piece returns to its original shape, the locked protrusion provided on the elastic piece fits into the first groove 68, and the rear guide 80 is Locked to the bottom plate 22.

  Thus, the sheet 6 placed on the placement surface 22A of the bottom plate 22 is positioned in the left-right direction 9 by the side guide mechanism 70 and positioned in the front-rear direction 8 by the rear guide 80 and the inclined plate 26.

  The inclined plate 26 is formed with an inclined surface 27 (an example of the inclined surface of the present invention) with which the rear end of the seat 6 in the front-rear direction 8 abuts or approaches. The inclined surface 27 extends rearward and obliquely upward from the rear end of the bottom plate 22 in the front-rear direction 8. The inclined surface 27 guides the sheet 6 fed from the bottom plate 22 by the feeding unit 40 to the conveyance path 30.

  In order to prevent double feeding of the sheet 6, a plurality of separation protrusions 28 made of metal pieces are provided on the inclined plate 26. Double feeding means that a plurality of sheets 6 are overlapped and sent to the conveyance path 30. Each separation protrusion 28 protrudes obliquely upward and forward from the inclined surface 27, and is arranged in a line along the rearward and upward direction. The separation protrusion 28 abuts on the lower sheet 6 among the plurality of sheets 6 stacked on the bottom plate 22, and separates the lower sheet 6 from the upper sheet 6. Thereby, double feeding is prevented. Since the sheet 6 is positioned by center alignment, the separation projection piece 28 is disposed at the central portion in the left-right direction 9 of the inclined plate 26 so as to be able to contact the sheet 6 of any size.

[Output Tray 29]
The paper discharge tray 29 has a rotation shaft (not shown) whose axis is in the left-right direction 9 (vertical direction in FIG. 2) at the rear end of the paper discharge tray 29 in FIG. The rotating shaft is rotatably supported by bearings (not shown) provided on the left and right side plates 23 and 24 of the main tray 21. The paper discharge tray 29 is rotated with the rear end portion in FIG. 2 as a rotation base end portion and the front end portion as a rotation front end portion, and is brought into a closed posture and an unillustrated open posture shown in FIG. The paper discharge tray 29 in the closed position is supported by the left and right side plates 23, 24 and the front plate 25 of the main tray 21, and receives the discharged sheet 6 after image recording. The paper discharge tray 29 is rotated by the user when the sheet 6 before image recording is supplied to the main tray 21.

  The paper discharge tray 29 has support portions 29A that protrude upward from the upper surface at the rear end portion in the front-rear direction 8 and the end portion in the left-right direction 9. The support portion 29A pushes and rotates a contact piece 144 of a tray sensor 140 described later when the paper feed cassette 20 is mounted on the main body 13. The tray sensor 140 is a sensor that detects that the paper feed cassette 20 is mounted on the main body 13. Details will be described later.

[Frame 90]
A frame 90 shown in FIG. 6 is arranged on the upper side of the paper feed cassette 20. The frame 90 holds a feeding unit 40, a platen 33, and a carriage 58, which will be described later.

  The frame 90 includes a main frame 91 and a pair of guide rails 92 and 93, and has a rectangular frame shape. The main frame 91 is formed by bending both ends of the steel plate in the left-right direction 9 upward, and includes a bottom plate (not shown) and a left side plate 95 and a right side plate 96 facing each other in the left-right direction 9. . The pair of guide rails 92 and 93 are formed so as to extend along the left-right direction 9. The pair of guide rails 92 and 93 are connected to the upper end of the left side plate 95 and the upper end of the right side plate 96, respectively, and face each other in the front-rear direction 8. The frame 90 supports a carriage 58 (described later) in a pair of guide rails 92 and 93 so as to be movable in the left-right direction 9.

[Feeding unit 40]
As shown in FIG. 2, the feeding unit 40 (an example of the feeding unit of the present invention) includes a support shaft 41 (an example of the support shaft of the present invention) rotatably supported on the bottom plate of the frame 90 (FIG. 6). ), An arm 42 (an example of the arm of the present invention) whose one end is rotatably supported on the support shaft 41, and a feed roller 43 (the present invention) rotatably supported on the other end of the arm 42. An example of a feeding roller). The support shaft 41 is rotated by an ASF motor 61 (FIG. 7). The ASF motor 61 is driven with the rotational speed controlled by the control unit 100 (FIG. 7).

  The arm 42 extends rearward and obliquely downward from the support shaft 41, and can rotate integrally with the support shaft 41 by a frictional force between the arm 42 and the support shaft 41. When the support shaft 41 is rotated, the arm 42 is rotated around the support shaft 41, and the feeding roller 43 provided at the rotation tip of the arm 42 is placed on the main tray 21. Abut. When the feeding roller 43 comes into contact with the sheet 6, the rotation of the arm 42 around the support shaft 41 is stopped.

  The arm 42 is provided with a plurality of gears 44. The gear 44 transmits the rotation of the support shaft 41 to the feed roller 43 and rotates the feed roller 43. The rotated feeding roller 43 feeds the uppermost sheet 6 in contact in the backward direction in the front-rear direction 8. The sheet 6 fed rearward is guided to the conveyance path 30 by the inclined plate 26 of the main tray 21.

[Conveyance path 30]
The conveyance path 30 (an example of the conveyance path of the present invention) includes a curved path 31 indicated by a one-dot chain line in FIG. 2 and a straight path 32 indicated by a two-dot chain line. The curved path 31 extends in a curved manner so as to go upward with the upper end of the inclined plate 26 of the main tray 21 as a base end and then forward in the front-rear direction 8. The straight path 32 extends linearly from the end of the curved path 31 toward the front. The conveyance path 30 is a space defined by a plurality of guide members (not shown) and a platen 33. When the sheet 6 is fed to the conveyance path 30, the sheet 6 is fed while being in contact with a plurality of guide members that define the conveyance path 30.

[Platen 33]
As shown in FIG. 6, the platen 33 (an example of the platen of the present invention) is disposed between the left side plate 95 and the right side plate 96 of the frame 90 and is positioned on the upper side of the paper feed cassette 20 (FIG. 2). Part of the lower surface of the straight path 32 (FIG. 2). A plurality of support ribs 33 </ b> A extending in the front-rear direction 8 protrude upward from the upper surface of the platen 33. A support surface for supporting the sheet 6 (an example of a support surface of the present invention) is formed by the upper end surfaces of the plurality of support ribs 33A.

  The width of the platen 33 in the left-right direction 9 is shorter than the length of the guide rails 92, 93 in the left-right direction 9. This is to allow a later-described media sensor 130 provided on the carriage 58 to pass above both ends of the sheet 6 on the platen 33 in the left-right direction 9. Details will be described later.

[Roller pairs 34, 37]
As shown in FIG. 2, the first roller pair 34 is disposed on the rear side in the front-rear direction 8 of the platen 33. The first roller pair 34 is disposed on the lower side of the conveyance roller 35 (an example of the conveyance roller of the present invention) rotatably supported on the frame 90 (FIG. 6), and is rotatable on the platen 33. And a driven roller 36 supported by the motor. The transport roller 35 is rotated by a PF motor 62 (FIG. 7). The PF motor 62 is driven with its rotational speed controlled by the control unit 100 (FIG. 7). The first roller pair 34 has a conveyance direction 85 (an example of the conveyance direction of the present invention) indicated by an arrow in FIG. ) To the sheet 6.

  The second roller pair 37 is provided on the front side of the platen 33 in the front-rear direction 8. The second roller pair 37 includes a paper discharge roller 38 rotatably supported by the platen 33, and a spur roller 39 disposed above the paper discharge roller 38 and rotatably supported by the frame 90 (FIG. 6). It is equipped with. The paper discharge roller 38 is rotated by a PF motor 62 (FIG. 7). The second roller pair 37 conveys the sheet 6 in the conveyance direction 85 with the sheet discharge roller 38 being rotated by the PF motor 62 so as to sandwich the sheet 6 in the conveyance path 30. The sheet 6 is intermittently conveyed on the platen 33 by the roller pairs 34 and 37, and an image is recorded by the recording head 51. The sheet 6 on which an image has been recorded is discharged to the paper discharge tray 29 of the paper feed cassette 20 by the second roller pair 37.

[Recording head 51]
As shown in FIG. 2, the recording head 51 (an example of the recording head of the present invention) is mounted on a carriage 58 (an example of the carriage of the present invention). As shown in FIG. 6, the carriage 58 is supported by guide rails 92 and 93 so as to be movable in the left-right direction 9 (an example of the first direction of the present invention). The carriage 58 is fixed to an endless annular belt 98. The belt 98 is wound around a drive pulley 99A and a driven pulley 99B provided on the shaft of the CR motor 63 (FIG. 7). The belt 98 includes teeth on the inner peripheral surface side that mesh with the teeth of the drive pulley 99A and the teeth of the driven pulley 99B. The belt 98 is circumferentially moved by driving the CR motor 63. Here, the drive pulley 99 </ b> A is disposed at the right end of the guide rail 93 in the left-right direction 9, and the driven pulley 99 </ b> B is disposed at the left end of the guide rail 93 in the left-right direction 9. Therefore, the carriage 58 can move between the left end portion and the right end portion in the left-right direction 9 of the guide rail 93, and can pass the upper side of the sheet 6 on the platen 33 in the left-right direction 9. The CR motor 63 is driven with the rotational speed controlled by the control unit 100 (FIG. 7).

  As shown in FIG. 6, the recording head 51 is connected to four ink cartridges 59 mounted on the cartridge mounting portion 19 by four ink tubes 45. Four color inks of black, cyan, magenta, and yellow stored in the four ink cartridges 59 are supplied to the recording head 51 through the ink tube 45.

  The recording head 51 includes a plurality of nozzles into which ink is introduced. As shown in FIG. 4, each nozzle has an ejection port 52 on the lower surface side of the recording head 51. The discharge ports 52 of the plurality of nozzles constitute four discharge port arrays 53 to 56. The discharge port arrays 53 to 56 are arranged in a line along the front-rear direction 8. Black ink flows into each nozzle constituting the ejection port array 53. One of cyan, magenta, and yellow ink flows into each nozzle constituting the ejection port arrays 54 to 56. The recording head 51 is electrically connected to the control board 18 (FIG. 2) by a flexible flat cable 49 shown in FIG. The recording head 51 ejects ink droplets from the ejection port 52 in response to a signal from the control unit 100.

  Incidentally, although the side guide mechanism 70 suppresses the skew of the sheet 6 when the sheet 6 is fed out, it is difficult to completely prevent the sheet 6 from being skewed. Due to the slight skew of the sheet 6, the position of the sheet 6 in the left-right direction 9 on the platen 33 may be different for each sheet 6. This is because a rotational moment acts on the sheet 6 in a direction orthogonal to the conveyance direction 85 by contacting the inclined plate 26 or the conveyance path 30 when the sheet 6 is fed. Further, depending on the user's operation, a gap may be generated between the guide members 71 and 72 of the side guide mechanism 70 and the seat 6. Then, the sheet 6 is skewed during feeding, and the position of the sheet 6 in the left-right direction 9 on the platen 33 is different for each sheet 6. Thus, the control unit 100 detects the end position of the sheet 6 in the left-right direction 9 using the sensor so that the position of the image recording range in the left-right direction 9 does not differ for each sheet 6. The printing start position of the recording head 51 in the left-right direction 9 is determined by the position. This will be described in detail below.

  The printer unit 11 is provided with a media sensor 130, a tray sensor 140, a registration sensor 150, a linear encoder 110, and a first rotary encoder 120 shown in FIG. The media sensor 130 and the linear encoder 110 are an example of the first detection unit of the present invention.

[Media sensor 130]
As shown in FIG. 4, the media sensor 130 includes a photo interrupter provided on the carriage 58. Specifically, the media sensor 130 includes a light emitting diode 131 that emits light downward, a photodiode 132 that receives light from the light emitting diode 131 reflected by the platen 33 or the sheet 6 on the platen 33, It has. The photodiode 132 outputs an amount corresponding to the intensity of the received light. This output is input to the control unit 100 (FIG. 7). The control unit 100 determines that the media sensor 130 has reached the upper side of the end of the sheet 6 in the left-right direction 9 due to the output change of the photodiode 132. The control unit 100 stores the position of the carriage 58 when the output of the photodiode 132 changes in the first storage area 104 of the memory 103 as the end position of the sheet 6 in the left-right direction 9. The position of the carriage 58 in the left-right direction 9 is detected by the linear encoder 110.

[Linear encoder 110]
As shown in FIG. 6, the linear encoder 110 includes an encoder strip 111 provided on the guide rail 93 and a photo interrupter 112 provided on the carriage 58. The encoder strip 111 has a strip-like outer shape that is long in the left-right direction 9, and is disposed across both ends of the guide rail 93 in the left-right direction 9. The encoder strip 111 has a light transmitting portion (not shown) that transmits light and a light shielding portion (not shown) that blocks light. The light transmitting portions and the light shielding portions are arranged so as to be alternately arranged in the left-right direction 9. The photo interrupter 112 includes a light emitting diode that emits light, and a photodiode that receives light from the light emitting diode and performs output in accordance with the intensity of the received light. The light emitting diodes and photodiodes of the photo interrupter 112 are arranged on both sides of the encoder strip 111 in the front-rear direction 8. When the carriage 58 is moved in the left-right direction 9, the photo interrupter 112 alternately passes through the light transmitting portions and the light shielding portions of the encoder strip 111. Therefore, the output of the photo interrupter 112 changes by the number of times corresponding to the amount of movement of the carriage 58. The output of the photo interrupter 112 is input to the control unit 100 (FIG. 7). The control unit 100 stores, in the first storage area 104 of the memory 103, the position where the output of the photo interrupter 112 when the output of the media sensor 130 changes is the end position of the sheet 6 in the left-right direction 9. The end position of the sheet 6 stored in the first storage area 104 is used by the control unit 100 to determine the print start position in the left-right direction 9. Details will be described later.

[Tray sensor 140]
The tray sensor 140 (an example of the second detection means of the present invention) shown in FIG. 2 is configured such that the paper feed cassette 20, that is, the main tray 21, is mounted on the main body 13, and the first position from the second position and the first position from the first position. This is a sensor for detecting that the position is two. The tray sensor 140 includes a rotating body 141 disposed on the upper side of the paper feed cassette 20 at the first position, and a photo interrupter 142 that detects the rotating position of the rotating body 141. The rotating body 141 includes a rotating shaft 143 whose central axis extends in the left-right direction 9 (a direction perpendicular to the paper surface of FIG. 2), an abutment piece 144 and a detector 145 protruding from the peripheral surface of the rotating shaft 143, It has. When the paper feed cassette 20, that is, the main tray 21 is in the second position, the contact piece 144 protrudes downward from the rotation shaft 143 as indicated by a broken line in FIG. 2. At this time, the detector 145 is out of the optical path of the photo interrupter 142 as shown by the broken line in FIG. When the main tray 21 is mounted on the main body 13 and positioned at the first position, the support portion 29A of the paper discharge tray 29 pushes the contact piece 144 and rotates the rotating body 141. Then, as shown by the solid line in FIG. 2, the detector 145 moves on the optical path of the photo interrupter 142, and the output of the photo interrupter 142 changes. The output of the photo interrupter 142 is input to the control unit 100 (FIG. 7). The control unit 100 determines that the main tray 21 has moved due to the output change of the photo interrupter 142.

  Upon receiving the print instruction, the control unit 100 determines whether the main tray 21 is located at the first position or the second position by operating the input from the tray sensor 140 before operating the feeding unit 40. To do. The control unit 100 operates the feeding unit 40 only when it is determined that the main tray 21 is located at the first position. In other words, when the control unit 100 determines that the main tray 21 is located at the second position, the control unit 100 does not operate the feeding unit 40. This is because if the feeding unit 40 is operated when the main tray 21 is located at the second position, a jam or the like may occur in the conveyance path 30.

  The tray sensor 140 is used to reset the count value of the counter 101 (FIG. 7) that counts the number of sheets 6 on which images have been recorded. Details will be described later.

[Registration sensor 150]
As shown in FIG. 2, the registration sensor 150 (an example of the first sensor of the present invention) is arranged near the roller pair 34 on the upstream side of the first roller pair 34 in the transport direction 85. The registration sensor 150 is used to detect the leading end position of the sheet 6. As shown in FIG. 5B, the registration sensor 150 includes a rotation shaft 151, a contact piece 152 protruding from the peripheral surface of the rotation shaft 151 to the conveyance path 30 (FIG. 2), and the rotation shaft 151. And a photo interrupter 154 that protrudes from the peripheral surface. The photo interrupter 154 includes a light emitting diode 155 and a photodiode 156 disposed to face the light emitting diode 155. The photodiode 156 outputs in accordance with the intensity of light incident from the light emitting diode 155.

  When the contact piece 152 is in the transport path 30 (FIG. 2), the detector 153 is on the optical path of the photo interrupter 154. When the sheet 6 is fed out by the feeding unit 40 (FIG. 2) and the leading end in the conveyance direction 85 (FIG. 2) of the sheet 6 pushes the abutting piece 152 to rotate the abutting piece 152, the detector 153 becomes a light emitting diode. 155 off the optical path. As a result, the output of the photodiode 156 changes. The output of the photodiode 156 is input to the control unit 100. The control unit 100 determines that the leading edge of the sheet 6 in the conveyance direction 85 (FIG. 2) of the sheet 6 has reached the registration sensor 150 due to the output change of the photodiode 156. When the rear end of the sheet 6 in the conveyance direction 85 passes the registration sensor 150, the rotation shaft 151 is returned to the original rotation position protruding into the conveyance path 30 by the elastic force of the torsion coil spring 157.

  The registration sensor 150 is used to detect the registration of the sheet 6 and the tip position of the sheet 6. The registration of the sheet 6 strikes the leading edge of the sheet 6 in the conveyance direction 85 against the stationary conveyance roller 35 or the conveyance roller 35 rotated in the direction opposite to the rotation direction in which the sheet 6 is conveyed in the conveyance direction 85. It is done by contacting. The detection of the leading end position of the sheet 6 is performed by the registration sensor 150 and the first rotary encoder 120 shown in FIG.

[First rotary encoder 120]
As shown in FIG. 5A, the first rotary encoder 120 includes a disk 121 provided on the rotation shaft 35 </ b> A of the transport roller 35 and a photo interrupter 122. The photo interrupter 122 includes a light emitting diode 123 and a photodiode (not shown). The disk 121 has a disk-like outer shape, and has a configuration in which a peripheral portion is inserted between the light emitting diode 123 and the photodiode. On the peripheral portion of the disk 121, a light transmitting portion and a light shielding portion (not shown) are provided so as to be alternately arranged in the circumferential direction of the disk 121. When the disk 121 is rotated by the rotation of the transport roller 35, the light transmitting portion and the light shielding portion alternately pass on the optical path of the light emitting diode 123, and the output of the photodiode changes. That is, the output of the photodiode changes by the number of times corresponding to the rotation amount of the transport roller 35. The output of the photodiode is input to the control unit 100 (FIG. 7). The controller 100 estimates the leading end position of the sheet 6 in the conveyance direction 85 (FIG. 2) based on the number of output changes of the photodiode.

[Control unit 100]
Hereinafter, a schematic configuration of the control unit 100 will be described with reference to FIG. The control part 100 performs 1st control according to the flowchart mentioned later. The control unit 100 (an example of the control means of the present invention) is realized by a microcomputer (not shown) mounted on the control board 18 (FIG. 2). The microcomputer includes a central processing unit (CPU), a ROM storing a control program, a RAM used as a data storage area or work area, a non-volatile memory 103, and the like. Each component is connected to the ASIC via a bus.

  The control unit 100 includes a counter 101 (an example of the counting unit of the present invention) formed by the above-described components, and a reset unit 102 (an example of the reset unit of the present invention) that resets the count value of the counter 101. .

  The counter 101 counts the number of sheets 6 on which images have been recorded. The control unit 100 monitors the output of the tray sensor 140. When the control unit 100 determines that the paper feed cassette 20, that is, the main tray 21 has been moved due to the output change of the tray sensor 140, the control unit 100 causes the reset unit 102 to reset the count value of the counter 101 and return it to an initial value (for example, zero). . The count value of the counter 101 is used for correcting the image recording range. Details will be described later. As described above, the output of the tray sensor 140 changes when the main tray 21 moves from the first position to the second position or when the main tray 21 moves from the second position to the first position. .

  The memory 103 has at least a first storage area 104 and a second storage area 105. The first storage area 104 stores the position of the carriage 58 when the output of the media sensor 130 changes. The second storage area 105 stores a preset first threshold value (an example of the first threshold value of the present invention). The first threshold value determines the number of sheets 6 for detecting the end position of the sheet 6 in the left-right direction 9 after it is detected that the paper feed cassette 20, that is, the main tray 21 has been moved. Details will be described later.

[Operation of Inkjet Recording Apparatus 10]
The operation of the inkjet recording apparatus 10 will be described with reference to FIG. When a printing instruction is input from the operation unit 17 (FIG. 1) or an external device (not shown) such as a personal computer, the control unit 100 (FIG. 7) drives the CR motor 63 (FIG. 7) to move the carriage 58. The guide rails 92 and 93 are moved toward the right end in the left-right direction 9. As a result, the initial position of the carriage 58 is determined at the right end of the guide rails 92 and 93.

  Next, the control unit 100 drives the ASF motor 61 (FIG. 7) to rotate the feeding roller 43, and sends the sheet 6 from the main tray 21 of the sheet feeding cassette 20 to the conveyance path 30. The control unit 100 determines that the output of the registration sensor 150 has changed and the leading edge of the sheet 6 in the conveyance direction 85 has reached the registration sensor 150. Thereafter, the control unit 100 reversely rotates the PF motor 62 (FIG. 7) to reversely rotate the transport roller 35 to perform registration. The reverse rotation is rotation opposite to the rotation direction (forward rotation) in which the sheet 6 is conveyed in the conveyance direction 85.

  Thereafter, the control unit 100 rotates the PF motor 62 in the forward direction and conveys the sheet 6 in the conveyance direction 85. At this time, the sheet 6 is stopped when the leading edge of the sheet 6 is positioned on the platen 33 at a predetermined print start position according to the image data.

  Next, the control unit 100 determines the print start position in the left-right direction 9 from the detection result of the media sensor 130 and the like, and drives the CR motor 63 (FIG. 7) to move the carriage 58 to the print start position. This control will be described in detail later. Note that the width of the image recording range in the left-right direction 9 is determined by the control unit 100 based on the image data. Thereafter, the control unit 100 drives the CR motor 63 to move the carriage 58 and operates the recording head 51 to perform printing for one line. At this time, the recording head 51 ejects ink droplets according to the determined print start position. When the printing for one line is completed, the control unit 100 drives the PF motor 62 to rotate the conveyance roller 35 and the paper discharge roller 38 in the forward direction, thereby conveying the sheet 6 for one line. The control unit 100 repeats printing for one line and conveyance for one line to record an image on the sheet 6. When the image recording on the sheet 6 is completed, the control unit 100 drives the PF motor 62 to rotate the paper discharge roller 38 and discharges the sheet 6 to the paper discharge tray 29.

  Next, the operation of the control unit 100 that determines the print start position in the left-right direction 9 will be described. When a printing instruction for one sheet 6 is input, the control unit 100 starts the operation of the first control (an example of the first control of the present invention) shown in the flowchart of FIG. First, the control unit 100 determines whether or not the count value of the counter 101 is less than the first threshold stored in the memory 103 (S1). When the control unit 100 determines that the count value of the counter 101 is less than the first threshold value (S1, Y), the control unit 100 starts an operation of detecting the end position of the sheet 6 in the left-right direction 9 (S2).

  In the end position detection operation, the control unit 100 rotates the CR motor 63 to move the carriage 58 at the initial position to the left. At this time, the control unit 100 monitors the output of the media sensor 130 and counts the number of changes in the output of the linear encoder 110 after driving the CR motor 63 with a counter (not shown). When the media sensor 130 reaches the left end and the right end in the left-right direction 9 of the sheet 6 on the platen 33, the output of the media sensor 130 changes. At this time, the control unit 100 stores the positions where the output of the linear encoder 110 has changed in the first storage area 104 of the memory 103 as the positions of the left end and the right end of the seat 6 (S3). That is, the first storage area 104 stores the positions of the left end and the right end in the left-right direction 9 of the sheet 6 on the platen 33.

  Next, the control unit 100 determines the print start position in the left-right direction 9 based on the edge position of the sheet 6 stored in the first storage area 104 and the image recording range determined by the image data included in the print instruction. (S4). The control unit 100 drives the CR motor 63 (FIG. 7) to move the carriage 58 to the determined print start position (S5). Thereafter, the control unit 100 performs an image recording operation in which printing for one line and conveyance for one line are alternately performed (S6). After the image recording operation ends, the control unit 100 increments the count value of the counter 101 and ends the operation.

  In step S1, when the control unit 100 determines that the count value of the counter 101 is not less than the first threshold value (S1, N), the edge position of the sheet 6 stored in the first storage area 104 of the memory 103, and the print instruction The printing start position in the left-right direction 9 is determined based on the image recording range determined based on the image data included in (S8). More specifically, the first storage area 104 stores the edge position of the sheet 6 detected until the count value of the counter 101 reaches the first threshold value. For example, when the first threshold value is “1”, the end position of one sheet 6 is stored in the first storage area 104. When the second threshold value is “2”, the end positions of two sheets 6 are stored in the first storage area 104.

  The control unit 100 determines the print start position in the left-right direction 9 using the end position of the sheet 6 on which an image has been recorded immediately before. Alternatively, the control unit 100 uses the end position of one sheet 6 stored in the first storage area 104 or the average value of the end positions of a plurality of sheets 6 to start the print start position in the left-right direction 9. To decide. After determining the print start position in step S8, the control unit 100 performs the operations in steps S5 to S7 and ends the operation.

[effect]
When the sheet feeding cassette 20, that is, the main tray 21 is slid by the user, when the sheet 6 approaches one of the guide members 71 and 72 or when the sheet 6 is skewed until reaching the platen 33, the sheet 6 is moved on the platen 33. The position in the left-right direction 9 may be different for each sheet 6. In this embodiment, since the end position of the sheet 6 is detected every time the movement of the main tray 21 is detected, the position accuracy of the image recording range can be kept high regardless of whether the main tray 21 is moved. Further, since the end position of the sheet 6 is detected only for a predetermined number of sheets 6 determined by the first threshold, the image recording time is shortened. Therefore, the inkjet recording apparatus 10 which is one embodiment of the present invention can maintain high image recording accuracy and can shorten the image recording time.

[Modification 1]
In this modification, an example in which a detection unit that detects the thickness of the layer of the sheet 6 placed on the main tray 21 (FIG. 2) is provided will be described. The detection unit includes a registration sensor 150 shown in FIG. 9 and a second rotary encoder 126 (an example of the encoder of the present invention) that detects the rotation amount of the feed roller 43. The registration sensor 150 and the second rotary encoder 126 are an example of third detection means of the present invention.

  The second rotary encoder 126 has the same configuration as that of the first rotary encoder 120 (FIG. 5A). However, the disc provided with the light transmitting portion and the light shielding portion is provided on the support shaft 41 (FIG. 2) of the feeding unit 40 and the rotating shaft of the ASF motor 61. Therefore, the output of the second rotary encoder 126 changes by the number of times corresponding to the rotation amount of the feeding roller 43. The output of the second rotary encoder 126 is input to the control unit 100.

  The control unit 100 counts the number of output changes of the second rotary encoder 126 from the start of driving of the ASF motor 61 until the output of the registration sensor 150 changes using a counter (not shown). The control unit 100 determines the thickness of the layer of the sheet 6 placed on the main tray 21 based on the count value of this counter. Details will be described below. As shown in FIG. 2, the leading end (the rear end in the front-rear direction 8) in the feeding direction of the sheet 6 placed on the main tray 21 is in contact with or close to the inclined surface 27. In addition, the uppermost sheet 6 fed by the feeding roller 43 is guided to the conveyance path 30 by the inclined surface 27. The height position of the uppermost sheet 6 is determined by the thickness of the layer of the sheet 6. Therefore, the thicker the layer of the sheet 6 is, the closer the uppermost sheet 6 is to the starting end of the conveying path 30 (the upper end of the inclined plate 26). As a result, the thicker the layer of the sheet 6 placed on the main tray 21, the shorter the transport distance from the leading edge of the uppermost sheet 6 to the registration sensor 150. That is, the number of output changes of the second rotary encoder 126 (FIG. 9) from the start of driving of the ASF motor 61 (FIG. 9) to the change of the output of the registration sensor 150 (FIG. 9) is reduced. The control unit 100 determines the thickness of the layer of the sheet 6 placed on the main tray 21 from the number of output changes of the second rotary encoder 126 from the start of driving of the ASF motor 61 until the output of the registration sensor 150 changes. .

  The control unit 100 determines whether or not the determined thickness of the layer of the sheet 6 is less than a second threshold value (an example of the second threshold value of the present invention) stored in the third storage area 106 of the memory 103. When the control unit 100 determines that the thickness of the layer of the sheet 6 is less than the second threshold, the reset unit 102 resets the count value of the counter 101 to return to the initial value.

  As the image recording on the sheet 6 progresses and the number of sheets 6 placed on the main tray 21 decreases, the inventor has found that the tendency of the positional deviation of the sheet 6 in the left-right direction 9 may be different from that immediately after replenishment. It was. This is because the contact distance between the inclined surface 27 and the sheet 6 differs depending on the thickness of the layer of the sheet 6. The thicker the layer of the sheet 6, the shorter the contact distance, while the thinner the layer of the sheet 6, the longer the contact distance. If the contact distance is different, the frictional state with respect to the sheet 6 is different. Therefore, the tendency of the positional deviation of the sheet 6 in the left-right direction 9 is different from that immediately after the sheet 6 is supplied. In this modification, when the number of sheets 6 placed on the main tray 21 decreases, that is, when the control unit 100 determines that the thickness of the sheet 6 is less than the second threshold, the count value of the counter 101 is changed. Reset. After that, since the edge position of the sheet 6 is detected again as in steps S1 to S4 shown in FIG. 8, it is possible to suppress a decrease in position accuracy of the image recording range in the left-right direction 9.

[Modification 2]
In this modification, instead of the second rotary encoder 126 (FIG. 9) of Modification 1, a rotating body 160 shown in FIG. 10 and photo interrupters 165 and 166 (an example of the second sensor of the present invention) are provided. The example given is explained. The rotating body 160 and the photo interrupters 165 and 166 are examples of the third detection unit.

  The rotating body 160 includes a rotating shaft 161 disposed on the upper side of the main tray 21, a contact piece 162 (an example of the contact piece of the present invention) protruding downward from the rotating shaft 161, and a rotating member. And a detector 163 protruding upward from the shaft 161. The contact piece 162 is in contact with the uppermost sheet 6 placed on the main tray 21 and rotated. When the thickness of the layer of the sheet 6 placed on the main tray 21 is equal to or less than the first amount, the contact piece 162 and the detector 163 are in the rotation position indicated by the broken line in FIG. When the thickness of the layer of the sheet 6 is equal to or greater than the second amount, the sheet 6 is in the rotational position indicated by the thick line in FIG. When the number of sheets 6 is an amount between the first amount and the second amount, the sheet 6 is in the rotational position indicated by the thin line in FIG. The detector 163 is on the optical path of the photo interrupter 166 when in the rotational position indicated by the thick line in FIG. 10, and is on the optical path of the photo interrupter 165 when in the rotational position indicated by the thin line in FIG. When it is in the rotation position indicated by the broken line in FIG. Outputs of the photo interrupters 165 and 166 are input to the control unit 100 (FIG. 7). The control unit 100 determines the thickness of the layer of the sheet 6 placed on the main tray 21 in three stages based on the output values of the photo interrupters 165 and 166.

  When the control unit 100 determines that the output of the photo interrupter 165 has changed after the output of the photo interrupter 166 has changed, the reset unit 102 resets the count value of the counter 101. Then, the process of step S1 thru | or S4 shown by FIG. 8 is performed. The count value of the counter 101 may be reset only when the control unit 100 determines that the output of the photo interrupter 165 has changed without providing the photo interrupter 166. However, when the photo interrupter 166 is provided, the detection of the edge position of the sheet 6 again can be omitted when the sheet 6 of the first number or less is supplied to the sheet feeding cassette 20. In the present modification, as in Modification 1, it is possible to suppress a decrease in position accuracy of the image recording range in the left-right direction 9.

[Modification 3]
In this modification, the control unit 100 (FIG. 7) monitors the count value of the counter 101, and is the count value equal to or greater than the third threshold value (an example of the third threshold value of the present invention) stored in the memory 103? Judge whether or not. When the control unit 100 determines that the count value of the counter 101 is equal to or greater than the third threshold, the reset unit 102 resets the count value of the counter 101 to return to the initial value. That is, when the number of sheets 6 on which image recording has been completed becomes equal to or greater than the third threshold value, the count value of the counter 101 is reset. Accordingly, it is possible to cope with a change in the tendency of the positional deviation of the sheet 6 in the left-right direction 9 as the image recording on the plurality of sheets 6 proceeds. In the present modification, as in Modification 1, it is possible to suppress a decrease in position accuracy of the image recording range in the left-right direction 9.

[Modification 4]
In the present modification, when the power of the inkjet recording apparatus 10 is turned on, the control unit 100 (FIG. 7) resets the count value of the counter 101 by the reset unit 102 and returns it to the initial value. Therefore, even if the user moves the paper feed cassette 20 while the power is off, the position accuracy of the image recording range does not deteriorate. Further, the reset by the reset unit 102 may be performed after the power-off instruction to the inkjet recording apparatus 10 is performed and before the inkjet recording apparatus 10 is powered off.

[Modification 5]
In this modification, the control unit 100 (FIG. 7) has a first recording mode and a second recording mode. The control unit 100 selects the first recording mode or the second recording mode according to information included in the print instruction.

  The first recording mode (an example of the first recording mode of the present invention) is a recording mode that determines whether or not to detect the end position of the sheet 6 based on the count value of the counter 101. That is, the first recording mode is a recording mode for executing the first control shown in the flowchart of FIG. The second recording mode (an example of the second recording mode of the present invention) is a recording mode in which the end position of the sheet 6 is detected regardless of the count value of the counter 101. When the second recording mode is selected, the control unit 100 moves the carriage 58 every time the sheet 6 is conveyed, detects the end position in the left-right direction 9 of the sheet 6, and uses the detected end position to perform the left-right direction. 9 determines the print start position.

[Other variations]
In the above-described embodiment, the example in which the paper feed cassette 20 is attached to and detached from the main body 13 by the slide has been described. However, the paper feed cassette 20 may be attached to and detached from the main body 13 by turning. Further, the sheet feeding cassette 20 may not be completely removed from the main body 13 as long as the sheet 6 can be replenished.

  Further, in the above-described embodiment, the example in which the sheet 6 is sent to the conveyance path 30 using the feeding unit 40 having the configuration in which the feeding roller 43 is rotatably supported by the arm 42 has been described. However, other existing configurations may be adopted as long as the sheet 6 can be sent out to the conveyance path 30. For example, the feed roller 43 is rotatably attached to the frame 90, and the bottom plate 22 of the paper feed cassette 20 attached to the main body housing 14 is urged toward the feed roller 43 by an elastic member, and is placed on the paper feed cassette 20. A configuration in which the placed sheet 6 is pressed against the feeding roller 43 may be employed. Further, a configuration in which the bottom plate 22 is pressed against the feeding roller 43 by a driving unit (not shown) may be employed.

  In the above-described embodiment, the side guide mechanism 70 that positions the sheet 6 by center alignment has been described. However, a side guide mechanism that positions the sheet 6 by aligning the end of the sheet 6 in the left-right direction 9 with any end of the main tray 21 in the left-right direction 9 may be used.

  In the above-described embodiment, an example in which the position of the left and right ends of the sheet 6 is detected by the media sensor 130 in consideration of an error in the length (width) of the sheet 6 in the left-right direction 9 has been described. However, when an error in the length (width) of the sheet 6 in the left-right direction 9 is not considered, that is, when the width of the sheet 6 is constant, only the left end or the right end of the sheet 6 is detected by the media sensor 130. A configuration in which the control unit 100 determines the printing start position in the left-right direction 9 may be employed.

  In the above-described embodiment, an example in which the seat 6 is brought into contact with or close to the inclined plate 26 by the rear guide 80 has been described. However, the seat 6 may be brought into contact with or close to the inclined plate 26 by the existing rear guide having another configuration.

  In the above-described embodiment, the example in which the rotation shaft 143 (FIG. 2) of the tray sensor 140 is provided separately from the rotation shaft 38A (FIG. 2) of the paper discharge roller 38 has been described. However, the rotating shaft 38A may be used as the rotating shaft of the tray sensor 140, and the contact piece 144 and the detector 145 may be provided on the rotating shaft 38A. Then, the rotation shaft 143 can be omitted, and the number of parts can be reduced.

  In the above-described embodiment, the configuration in which the rotation of the rotation shaft 143 (FIG. 2) of the tray sensor 140 is detected by the photo interrupter 142 has been described. However, the rotation of the rotation shaft 143 may be detected by a mechanical switch such as a tact switch or a micro switch. The mechanical switch is pressed and turned on by the rotated detector 145. The control unit 100 detects whether the paper feed cassette 20 is attached to the main body 13 by turning on and off a mechanical switch.

  Further, a mechanical switch that is turned on by being directly pressed by the paper feed cassette 20 mounted on the main body 13 may be provided in the main body housing 14 instead of the tray sensor 140.

  In the first and second modified examples, the example in which the thickness of the sheet 6 is detected by the registration sensor 150 and the second rotary encoder 126, the rotating body 160, and the photo interrupters 165 and 166 has been described. However, the thickness of the layer of the sheet 6 may be detected using an existing distance sensor or displacement sensor.

  In the above-described embodiment, the media sensor 130 using the photo interrupter has been described. However, as long as the end position of the sheet 6 can be detected, another existing sensor may be used as the media sensor.

  In the above-described embodiment, the example in which the position of the carriage 58 is detected by the linear encoder 110 has been described. However, other existing sensors may be used as long as the position of the carriage 58 can be detected.

  In the above-described embodiment, the example in which the initial value of the count value of the counter 101 is zero and the count value is incremented each time an image is recorded on the sheet 6 has been described. However, the initial value of the counter 101 may be N (for example, N = 2, 3), and the count value may be decremented each time an image is recorded on the sheet 6. In this case, the control unit 100 determines whether or not the count value of the counter 101 is equal to or less than a first threshold value (for example, “1”) stored in the memory 103 in step S1 of FIG. If it is determined that the value is above the first threshold, the operation of step S2 is performed. When the control unit 100 determines that the count value of the counter 101 is equal to or less than the first threshold value, the control unit 100 performs the operation of step S8.

  In the above-described embodiment, the counter 101 and the reset unit 102 have been described as part of what constitutes the control unit 100. However, the counter 101 and the reset unit 102 may be realized by a control program stored in the memory 103.

6 ... Seat 9 ... Left-right direction (first direction)
DESCRIPTION OF SYMBOLS 10 ... Inkjet recording apparatus 20 ... Paper feed cassette 21 ... Main tray (tray)
27 ... Inclined surface 30 ... Conveying path 33 ... Platen 35 ... Conveying roller 40 ... Feeding section 41 ... Support shaft 42 ... Arm 43 ... Feeding roller 51- ..Recording head 58 ... carriage 70 ... side guide mechanism 80 ... rear guide 85 ... conveying direction 100 ... control unit (control means)
101 ... Counter (counting means)
102... Reset unit (reset means)
103. Memory (storage means)
110: Linear encoder 126: Second rotary encoder (encoder)
130: Media sensor 140: Tray sensor (second detection means)
150 ... Registration sensor (first sensor)
162: contact pieces 165, 166: photo interrupter (second sensor)

Claims (6)

A feeding unit that contacts the sheet and feeds the sheet to the conveyance path;
A tray on which the stacked sheets are placed, a top position where the uppermost sheet can be fed by the feeding section, and a tray where the uppermost position sheet can be moved to a second position where the feeding section cannot feed ,
A conveyance roller for conveying the sheet sent to the conveyance path by the feeding unit;
A platen provided with a support surface for supporting a sheet conveyed by the conveyance roller;
A carriage that is capable of reciprocating in a first direction orthogonal to the conveying direction of the sheet by the conveying roller, and disposed opposite the platen with respect to the sheet that is conveyed with the platen;
A recording head mounted on the carriage and ejecting ink droplets onto a sheet supported by the support surface;
First detecting means for detecting an end in the first direction of the sheet supported by the support surface in the movement in the first direction by the movement of the carriage;
Second detection means for detecting that the tray has moved from the second position to the first position or from the first position to the second position;
Storage means for storing the position of the end detected by the first detection means;
Counting means for counting the number of sheets on which images are recorded;
Reset means for resetting the count value of the counting means to a value less than a first threshold when detected by the second detecting means;
After reset of the count value of the reset unit, on condition that the count value of said counting means is less than the first threshold value, to the first detecting means to perform the detection of the end, the sensed the end The first detection means is stored on the storage means, determines an image recording range in the first direction based on the position of the end, and the count value of the counting means is not less than the first threshold value. Control means for executing the first control for determining the image recording range based on the position of the edge stored in the storage means without performing the detection of the edge.
An ink jet recording apparatus, wherein the recording head ejects ink droplets in accordance with the image recording range determined by the control means. Further comprising third detection means for detecting the thickness of the layer of sheets stacked on the tray;
The reset means resets the count value of the counting means to a value less than the first threshold on condition that the thickness detected by the third detecting means reaches a second threshold. The ink jet recording apparatus described. The tray further includes an inclined surface that rises inclined from the mounting surface on which the sheet is mounted,
The feeding section is
A spindle,
An arm supported rotatably about the support shaft;
A feed roller that is rotatably provided at the rotating tip of the arm and is capable of contacting the uppermost sheet, and feeding the sheet to the inclined surface side by rotating in contact with the sheet. And
The third detecting means includes
A first sensor that is disposed in the transport path and detects a leading edge of the sheet being fed by the feeding roller in the transport direction;
The inkjet recording apparatus according to claim 2, further comprising an encoder that detects a rotation amount of the feeding roller. The tray further includes an inclined surface that rises inclined from the mounting surface on which the sheet is mounted,
The feeding section is
A spindle,
An arm supported rotatably about the support shaft;
A feed roller that is rotatably provided at the rotating tip of the arm and is capable of contacting the uppermost sheet, and feeding the sheet to the inclined surface side by rotating in contact with the sheet. And
The third detecting means includes
A contact piece that is pivotally provided on the upper side of the tray in the first position and is in contact with the upper surface of the sheet at the uppermost position of the sheet layer;
The inkjet recording apparatus according to claim 2, further comprising: a second sensor that detects a rotational position of the contact piece. 5. The inkjet recording apparatus according to claim 2 , wherein the reset unit resets the count value to a value less than the first threshold value when the count value of the count unit reaches a third threshold value. 6. The control means has a first recording mode for performing the first control and a second recording mode for causing the first detection means to detect the edge of the sheet regardless of the count value of the counting means. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is used.

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