JP5659662B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus including a curved conveyance path capable of guiding a sheet and capable of conveying the sheet along the conveyance path by a pair of rollers provided in the conveyance path.

  Many image recording apparatuses capable of recording an image on a sheet include a sheet conveyance path therein, and at least one roller pair in the conveyance path. Such an image recording apparatus conveys the sheet along the conveyance path by sandwiching the sheet between the roller pair. The roller pair is composed of a driving roller and a driven roller.

  In many image recording apparatuses, a part of the conveyance path is curved so that the sheet conveyed through the conveyance path is U-turned in order to reduce the size of the apparatus. Patent Document 1 discloses an image recording apparatus having such a curved conveyance path. In some image recording apparatuses, at least one of the above-described roller pairs is provided in a curved conveyance path.

  Further, the image recording apparatus is provided above the tray for storing the sheet, and is provided at an end portion of the arm and provided with an arm that is provided so as to be rotatable up and down around a predetermined rotation axis. And a feeding roller that feeds the sheet stored in the tray to the curved conveyance path.

JP 2010-83601 A

  Normally, in an image recording apparatus that includes a feeding roller and a roller pair is provided in a curved conveyance path, the sheet is fed from the tray to the roller pair by the feeding roller. When the sheet reaches the roller pair, the driving of the feeding roller is stopped and the driving roller constituting the roller pair is driven. Thereafter, the sheet is conveyed on the curved conveyance path by the roller pair.

  The sheet conveyed on the curved conveyance path by the roller pair collides with a guide surface that divides the curved conveyance path on the downstream side in the conveyance direction from the roller pair. Since the guide surface is curved, the sheet that has collided with the guide surface is further conveyed to bend along the guide surface. As a result, one surface of the sheet comes into contact with the guide surface. When the sheet and the guide surface come into contact with each other, a force in the direction opposite to the conveyance direction is generated with respect to the sheet. The reverse force increases as the area where one surface of the sheet is in contact with the guide surface increases. When the reverse force is greater than the force with which the driving roller conveys the sheet, the sheet is not conveyed even though the driving roller is rotating. That is, the roller surface of the driving roller slips on the surface of the sheet. Such a slip may deteriorate the roller surface of the driving roller. If the sheet comes into contact with the deteriorated roller surface of the driving roller, the surface of the sheet may be adversely affected. When an image is recorded on such a sheet surface, the image quality of the image may be degraded. There is.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce deterioration of a roller that conveys a sheet, and to maintain an image quality of an image recorded on the sheet favorably. Is to provide.

(1) The image recording apparatus of the present invention is formed of an inner guide surface and an outer guide surface facing the inner guide surface, and a curved path through which the sheet is curved and guided along the conveyance direction, and the curved A linear path extending from the path, and a linear path on which a sheet passing through the curved path is guided along the conveyance direction, a tray on which a sheet can be placed, and the conveyance path A feeding roller that comes into contact with the sheet placed on the tray on the inner guide surface side and supplies the sheet to the curved path in the conveying direction, and a driving force provided on the outer guide surface side of the curved path. It is composed of a drive roller that is rotated by being transmitted and that can be idle when no drive force is transmitted , and a driven roller that is provided on the inner guide surface side of the curved path so as to face the drive roller. Cage A pair of conveying rollers that conveys the sheet that has been supplied to the curved path by the feeding roller to the straight path, a leading end determination unit that determines a leading end position of the sheet guided along the curved path, A drive unit that is provided on the outer guide surface side and that records an image on a sheet; and a control unit that controls driving of the feeding roller and the drive roller. In addition, in the portion constituting the curved path on the downstream side, a sheet support portion that is a plane from the position immediately below the conveying direction at the position where the driving roller is provided to the straight path side is provided. The control unit drives the feeding roller in a state where the driving force is not transmitted to the driving roller based on the conveyance start command, and the leading end determination unit reaches the leading end of the sheet at the sheet supporting unit. The first processing mode for starting the driving roller is provided on the condition that it has been determined.

  In the above-described configuration, the portion of the outer guide surface that forms the curved path on the downstream side of the drive roller is a plane that goes from the downstream side in the conveying direction at the position where the drive roller is provided to the straight path side. It is not curved. That is, the sheet that has passed through the driving roller needs to be transported by changing its direction in the direction along the plane after the leading end of the sheet collides with the plane. When the direction is changed, the force in the direction opposite to the conveying direction that the sheet receives from the plane is large. However, after the direction is once changed, the sheet is conveyed in a state where only the vicinity of the front end is in contact with the flat surface. That is, the area where one surface of the sheet abuts on a flat surface is small. Therefore, the force in the direction opposite to the conveyance direction that the sheet receives from the plane is small.

  In the above-described configuration, the sheet is conveyed by the feeding roller when the direction is changed in the direction opposite to the conveying direction. At this time, the roller surface of the feeding roller may slip on the surface of the sheet. However, even when the slip occurs, the image quality of the image recorded on the sheet by the recording unit is maintained well.

  The reason will be described below. In the above-described configuration, the feeding roller is in contact with the sheet on the inner guide surface side, the driving roller is in contact with the sheet on the outer guide surface side, and the recording unit is on the outer guide surface side of the sheet. Record the image against the surface. That is, the surface of the sheet that contacts the feeding roller is the surface opposite to the surface on which the image is recorded.

  In the above-described configuration, the sheet is conveyed by the pair of conveyance rollers after the direction change in which the force in the direction opposite to the conveyance direction is small. Therefore, it is unlikely that the roller surface of the driving roller of the conveying roller pair slips on the surface of the sheet. Thereby, the image quality of the image recorded on the sheet by the recording unit can be maintained satisfactorily.

  (2) The control unit stops the driving of the feeding roller on the condition that the leading edge determination unit determines that the leading edge of the sheet has reached the sheet holding position by the conveying roller pair, and the driving A second processing mode for starting the driving of the roller is further provided, and the first processing mode or the second processing mode is selected and executed based on type information indicating the type of the sheet placed on the tray.

  When the sheet conveyed through the conveyance path is a sheet having rigidity higher than that of plain paper, for example, thick paper, a force in the direction opposite to the conveyance direction that the sheet receives from the guide surface increases. For this reason, the phenomenon that the roller surface of the driving roller slips on the surface of the sheet is likely to occur. In addition, when the sheet conveyed on the conveyance path is a sheet having a special coating on the surface on which the image is recorded, for example, glossy paper, when the roller surface of the driving roller deteriorates, the sheet contacts with the roller surface. As a result, the coating is adversely affected and the image quality of the image recorded on the sheet may be deteriorated.

  On the other hand, when the sheet conveyed through the conveyance path is a low-rigidity sheet, for example, plain paper, there is a low possibility that the above-described slip or image quality degradation will occur. Therefore, when the leading edge of the sheet is positioned at the sheet holding position of the conveying roller pair, the sheet is not driven by the driving roller of the conveying roller pair, but by the feeding roller located upstream of the driving roller in the conveying direction. When conveyed, the following problems may occur. That is, in this case, since the leading edge of the sheet is too far from the feeding roller, the conveyance direction of the sheet may not be stable. This increases the possibility of sheet jamming in the conveyance path.

  In the above configuration, the control unit selects and executes the first processing mode or the second processing mode based on the type information indicating the type of the sheet. For example, when a highly rigid sheet and a sheet with a special coating are conveyed on the conveyance path, the first processing mode may be executed, which may cause the above-described slip and image quality degradation. Can be lowered. In addition, when a sheet having low rigidity is conveyed on the conveyance path, the second processing mode is executed, so that the conveyance of the sheet to the conveyance path on the downstream side of the conveyance roller pair is greater than that of the feeding roller. This is done by a drive roller located near the leading edge of the sheet. As a result, the possibility of occurrence of sheet jams as described above can be reduced.

  (3) The leading edge determination unit is provided upstream of the conveyance roller pair in the conveyance direction, detects a leading edge of the sheet guided along the curved path, and drives the feeding roller. And a drive amount detection unit for detecting the amount. The leading end position of the sheet is determined based on the driving amount of the feeding roller detected by the driving amount detecting unit after the leading end of the sheet is detected by the detecting unit.

  Thereby, for example, the front end position of the sheet is determined more accurately than the front end position of the sheet is determined based only on the driving amount of the feed roller from the start of driving of the feed roller without providing a detection unit. Can do.

  (4) The image recording apparatus of the present invention includes a drive source, a drive transmission switching mechanism that selectively switches transmission of driving force from the drive source to the feeding roller or the drive roller, and the drive transmission switching mechanism. A first drive transmission mechanism that transmits drive to the feeding roller and a second drive transmission mechanism that transmits drive from the drive transmission switching mechanism to the drive roller are further provided. The drive roller can idle in a state where the drive is transmitted from the drive source to the feed roller by the first drive transmission mechanism.

  In the above-described configuration, the driving roller and the feeding roller are driven by a common driving source. Thereby, the number of drive sources mounted on the image recording apparatus can be reduced. As a result, the image recording apparatus can be reduced in size. In addition, the cost of the image recording apparatus can be reduced.

  In the present invention, when the force in the direction opposite to the conveyance direction received by the sheet is large, the sheet is conveyed by the feeding roller, and when the force in the direction opposite to the conveyance direction received by the sheet is small, the sheet is conveyed. It is conveyed by a pair of rollers. Thereby, the possibility that the roller surface of the driving roller of the pair of conveying rollers slips on the surface of the sheet can be reduced. As a result, it is possible to maintain good image quality of the image recorded on the sheet by the recording unit.

FIG. 1 is an external perspective view of a multifunction machine 10 that is an example of an embodiment of the present invention. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a longitudinal sectional view schematically showing the drive transmission switching mechanism 110 and the drive transmission mechanisms 27 and 115. FIG. 4 is a longitudinal sectional view showing the internal structure of the printer unit 11. FIG. 5 is a block diagram illustrating a configuration of the control unit 130. FIG. 6 is a flowchart illustrating an example of a transport control procedure performed by the control unit 130. FIG. 7 is a cross-sectional view showing a part of the outer guide member 17 when a rib is provided. FIG. 7 (A) shows a case where the rib is rectangular, and FIG. 7 (B) shows that the rib is triangular. The case is shown.

  Hereinafter, embodiments of the present invention will be described. The embodiment described below is merely an example of the present invention, and it is needless to say that the embodiment of the present invention can be changed as appropriate without departing from the gist of the present invention. In the following description, the vertical direction 7 is defined with reference to a state in which the multifunction machine 10 is installed (the state shown in FIG. 1), and the side in which the opening 13 is provided is the front side (front side). And the left-right direction 9 is defined when the multifunction machine 10 is viewed from the front side (front side).

[Multifunction machine 10]
As shown in FIG. 1, a multifunction machine 10 as an example of an image recording apparatus of the present invention is formed in a generally thin rectangular parallelepiped, and is provided with a printer unit 11 of an ink jet recording system in the lower part. The multifunction machine 10 has various functions such as a facsimile function and a print function. In the present embodiment, the multifunction device 10 having only a single-sided image recording function as a print function is described, but the multifunction device 10 may have a double-sided image recording function. The printer unit 11 includes a housing 14 having an opening 13 formed in the front, and a paper feed tray 20 (an example of the tray of the present invention) and a paper discharge tray 21 can be inserted and removed from the opening 13 in the front-rear direction 8. . A recording paper (an example of the sheet of the present invention) of a desired size is placed on the paper feed tray 20.

  As shown in FIG. 2, the printer unit 11 includes a paper feeding unit 15 that feeds recording paper, an ink jet recording type recording unit 24 that records an image on the recording paper (an example of the recording unit of the present invention), and the like. I have. The printer unit 11 records an image on a recording sheet based on print data received from an external device.

[Paper Feeder 15]
As shown in FIG. 2, the paper feed unit 15 is provided on the upper side of the paper feed tray 20. The paper feed unit 15 includes a paper feed roller 25 (an example of the feed roller of the present invention), a paper feed arm 26, and a first drive transmission mechanism 27 (first of the present invention), which will be described later, formed by meshing a plurality of gears. An example of a drive transmission mechanism). The paper feed roller 25 is pivotally supported at the tip of the paper feed arm 26. The paper feed arm 26 rotates in the direction of an arrow 29 about a shaft 28 provided at the base end. Thereby, the paper feed roller 25 can be brought into contact with and separated from the paper feed tray 20. That is, the paper feed roller 25 can contact the recording paper placed on the paper feed tray 20. The sheet feeding roller 25 is rotated by a driving force of a second driving motor 102 (see FIGS. 3 and 5, which is an example of the driving source of the present invention), which will be described later, by the first driving transmission mechanism 27. The sheet feeding roller 25 is in contact with the uppermost recording sheet among the recording sheets stacked on the sheet feeding tray 20 and separates the recording sheet from other recording sheets, and will be described below. Supply to the curved path 66.

  As shown in FIG. 2, when the recording paper is supplied to the curved path 66 by the paper feed roller 25, the surface of the recording paper that is in contact with the paper feed roller 25 is the curved path. 66 on the inner guide surface 19A side. On the other hand, the surface on the back side of the surface of the recording paper that is in contact with the paper feed roller 25 is the outer guide surface 17 </ b> A side with respect to the curved path 66.

[Conveyance path 65]
As shown in FIG. 2, inside the printer unit 11, a conveyance path through which the recording paper can be guided from the front end (back end) of the paper feed tray 20 to the paper discharge tray 21 through the recording unit 24. 65 (an example of the conveyance path of the present invention) is formed.

  The conveyance path 65 includes a curved path 66 (an example of the curved path of the present invention) formed between the leading end of the paper feed tray 20 and a first roller pair 58 described later, and the first roller pair 58 to the recording unit 24. It is divided into a straight path 67 (an example of a straight path of the present invention) formed between the sheet discharge tray 21 and the direct path. That is, the curved path 66 and the straight path 67 are arranged in the transport path 65.

  The curved path 66 is a curved path extending from the vicinity of the front end of the paper feed tray 20 to the first roller pair 58. The recording paper is guided while being curved along the curved path 66 in the conveyance direction (the direction indicated by the one-dot chain line in FIG. 2) in the conveyance direction (the direction of the arrow attached to the one-dot chain line in FIG. 2). The curved path 66 is continuous with the straight path 67 with the first roller pair 58 interposed therebetween. As a result, the recording sheet is guided to the straight path 67 through the curved path 66. The curved path 66 is partitioned by an inner guide member 19 and an outer guide member 17 that face each other at a predetermined interval. That is, the curved path 66 includes an inner guide surface 19A (an example of the inner guide surface of the present invention) that forms the rear surface of the inner guide member 19, and an outer guide surface 17A (the outer side of the present invention) that forms the front surface of the outer guide member 17. An example of a guide surface).

  As will be described later, a part of the outer guide surface 17A is a flat surface, and the other part is a curved surface.

  The inner guide surface 19A and the outer guide surface 17A may be configured by one surface or may be configured by a plurality of surfaces. Here, the case of being constituted by a plurality of surfaces means, for example, that the plurality of ribs extending along the conveyance path 65 are from the side facing the conveyance path 65 of the inner guide member 19 and / or the outer guide member 17. This is a case of projecting toward the conveyance path 65. In this case, the tip of each of the plurality of ribs is formed by one surface. That is, the inner guide surface 19A and the outer guide surface 17A are composed of a plurality of surfaces.

  The straight path 67 is a linear path extending in the front-rear direction 8 from the downstream end of the curved path 66 in the conveyance direction, that is, from the first roller pair 58 to the discharge tray 21. The recording sheet is guided along the straight path 67 in the conveyance direction (the direction of the arrow attached to the two-dot chain line in FIG. 2). That is, the recording sheet is guided along a straight path 67 extending linearly. The recording sheet is discharged to the discharge tray 21 after an image is recorded by the recording unit 24. The straight path 67 is formed by the recording unit 24 and the platen 42 facing each other with a predetermined interval at a location where the recording unit 24 is provided, and at a location where the recording unit 24 is not provided. The upper guide member 52 and the lower guide member 53 are opposed to each other with a gap therebetween. That is, similarly to the curved path 66, in the straight path 67, the upper guide surface 52A constituting the lower surface of the upper guide member 52 is an example of the inner guide surface of the present invention, and constitutes the upper surface of the lower guide member 53. The lower guide surface 53A is an example of the outer guide surface of the present invention.

[Recording unit 24]
As shown in FIG. 2, the recording unit 24 is provided on the upper side of the straight path 67, that is, on the upper guide surface 52 </ b> A side of the straight path 67. The recording unit 24 includes a carriage 40 that mounts the recording head 38 and reciprocates in the main scanning direction (direction perpendicular to the paper surface of FIG. 2). Ink is supplied to the recording head 38 from an ink cartridge (not shown). The recording head 38 ejects ink from the nozzle 39 as fine ink droplets. As the carriage 40 reciprocates in the main scanning direction, the recording head 38 is scanned with respect to the recording paper, and recording is carried on a platen 42 provided opposite to the recording unit 24 below the straight path 67. An image is recorded on the paper. The platen 42 supports the recording paper.

[First roller pair 58 and second roller pair 59]
As shown in FIG. 2, on the upstream side in the transport direction from the recording unit 24, the first transport roller 60 disposed above the curved path 66 and the straight path 67 and the lower side of the curved path 66 and the straight path 67. In addition, a first roller pair 58 including a pinch roller 61 disposed to face the first conveying roller 60 is provided. The pinch roller 61 is pressed against the roller surface of the first conveying roller 60 by an elastic member (not shown) such as a spring. The first roller pair 58 holds the recording paper and feeds it onto the platen 42.

  From the recording unit 24 on the downstream side in the transport direction, a second transport roller 62 disposed below the straight path 67 and a spur 63 disposed on the upper side of the straight path 67 so as to face the second transport roller 62. A second roller pair 59 is provided. The spur 63 is pressed against the roller surface of the second transport roller 62 by an elastic member (not shown) such as a spring. The second roller pair 59 pinches the recording paper that has passed through the recording unit 24 and conveys it to the paper discharge tray 21.

  The first transport roller 60 and the second transport roller 62 are rotated by the rotational driving force transmitted from the first drive motor 103 (see FIG. 5). When the first drive motor 103 is rotated forward or backward, the recording paper is transported in the transport direction.

[Third roller pair 55]
As shown in FIG. 2, on the upstream side of the first roller pair 58 in the transport direction, a third transport roller 56 (an example of the drive roller of the present invention) disposed on the outer guide surface 17A side, and an inner guide surface A third roller pair 55 (an example of a conveying roller pair of the present invention) is provided which is a pinch roller 57 (an example of a driven roller of the present invention) disposed on the 19A side. The pinch roller 57 is provided to face the third transport roller 56 and is pressed against the roller surface of the third transport roller 56 by an elastic member (not shown) such as a spring. The third roller pair 55 sandwiches the recording sheet and conveys it toward the first roller pair 58.

[Drive transmission switching mechanism 110]
As shown in FIG. 3, the sheet feeding roller 25 has a rotational driving force from the second drive motor 102 via the drive transmission switching mechanism 110 (an example of the drive transmission switching mechanism of the present invention) and the first drive transmission mechanism 27. Transmitted and rotated. The third transport roller 56 is connected to the drive transmission switching mechanism 110 from the second drive motor 102 and a second drive transmission mechanism 115 (an example of the second drive transmission mechanism of the present invention) in which a plurality of gears are engaged. The rotational driving force is transmitted and rotated.

  The drive transmission switching mechanism 110 includes a sun gear 113 that meshes with the intermediate gear 44 that transmits the rotational driving force from the second drive motor 102, and a planet gear 114 that rotates while revolving around the sun gear 113. The planet gear 114 meshes with one of the gears constituting the second drive transmission mechanism 115 by revolving around the sun gear 113 when the second drive motor 102 rotates in the reverse direction (see arrow 117) (114). (See dashed line). On the other hand, the planet gear 114 meshes with one of the gears constituting the first drive transmission mechanism 27 by revolving around the sun gear 113 when the second drive motor 102 rotates forward (see arrow 116). (See 114 solid line). With the above configuration, the drive transmission switching mechanism 110 transmits the driving force of the second driving motor 102 that rotates in the forward direction to the paper feeding roller 25, and transmits the driving force of the second driving motor 102 that rotates in the reverse direction to the third conveying roller 56. To do. In other words, the drive transmission switching mechanism 110 selectively switches the transmission of the driving force from the second drive motor 102 to the paper feed roller 25 or the third transport roller 56.

  The third transport roller 56 is in a state where no driving force is transmitted from the second drive motor 102, in other words, in a state where the planet gear 114 is not engaged with one of the gears constituting the second drive transmission mechanism 115. However, it is configured to be idle. As a result, when the recording paper conveyed by the paper feed roller 25 is in contact with the third conveyance roller 56 and the recording paper is further conveyed by the paper supply roller 25, the third conveyance roller 56 is in contact with the recording paper. Rotates as the paper is transported.

[Plane 22]
As shown in FIGS. 2 and 4, many portions of the outer guide surface 17 </ b> A of the outer guide member 17 are configured with curved surfaces to form a curved path 66. However, the outer guide surface 17A of the outer guide member 17 is not a curved surface but a flat surface 22 (corresponding to the flat surface of the present invention from the position 17B where the third transport roller 56 is provided). An example of a sheet support portion). Here, the position 17B is specifically the downstream edge of the recess 64 provided for inserting the shaft of the third transport roller 56 in the transport direction.

  The portion constituted by the plane 22 in the curved path 66 may be from the position 17B to the downstream end in the conveyance direction of the curved path 66, or from the position 17A to the middle of the downstream end in the conveyance direction. In the present embodiment, the outer guide surface 17 </ b> A is configured by a flat surface 22 from a position 17 </ b> A to a position 17 </ b> C that is substantially between the third roller pair 55 and the first roller pair 58. On the other hand, the outer guide surface 17A is curved on the downstream side in the transport direction from the position 17C.

  The plane 22 extends forward and obliquely upward from the position 17A. Specifically, the plane 22 is an inclined surface such that the position in the vertical direction 7 becomes upward as it goes from the position 17B to the position 17C, that is, toward the front.

  As described above, the outer guide surface 17A may be composed of a plurality of surfaces. Therefore, the flat surface 22 that constitutes a part of the outer guide surface 17A may also be composed of a plurality of surfaces. For example, the structure which the some rib extended along the conveyance path 65 protrudes toward the conveyance path 65 from the side which faces the conveyance path 65 of the plane 22 may be sufficient. In this case, the tip of each of the plurality of ribs is formed by one surface. That is, the plane 22 is composed of a plurality of surfaces.

  In the present embodiment, the shape of the rib described above is a shape having a rectangular cross section as shown in FIG. 7A, but the shape of the rib is not limited to a rectangle. For example, as shown in FIG. 7B, the rib may have a triangular cross section. In this case, the tip of the rib is pointed. That is, the tip of each rib is constituted by an elongated surface that is generally linear.

[Front end determination unit 120]
As shown in FIG. 2, the printer unit 11 is a detection unit 121 (an example of the detection unit of the present invention) for detecting the leading end position of a recording sheet fed from the paper feed tray 20 and conveyed through the curved path 66. And a front end determination unit 120 (an example of a front end determination unit of the present invention) including a rotary encoder 122 (an example of a drive amount detection unit of the present invention) that detects the rotation amount of the paper feed roller 25. In FIG. 4, the tip determination unit 120 is omitted.

  The detection unit 121 is provided on the upstream side in the conveyance direction with respect to the third roller pair 55 in the curved path 66. The detecting unit 121 includes, for example, a photo interrupter having a rotating body 112 having detectors 112A and 112B, a light emitting element (for example, a light emitting diode), and a light receiving element (for example, a phototransistor) that receives light emitted from the light emitting element. The optical sensor 111 is configured. The rotating body 112 is provided to be rotatable about a support shaft 123. The detector 112A protrudes from the support shaft 123 into the curved path 66. In a state where no external force is applied to the rotator 112, the detector 112B enters an optical path from the light emitting element to the light receiving element of the optical sensor 111 and blocks light passing through this optical path. When the rotator 112 is rotated by being pushed by the leading edge of the recording paper, the detector 112B moves out of the optical path from the light emitting element to the light receiving element of the optical sensor 111, and light passes through this optical path.

  The rotary encoder 122 is attached to the shaft 28 and includes an encoder disk 124 and an optical sensor 125 that rotate together with the shaft 28. The encoder disk 124 is formed with a pattern in which transmissive portions that transmit light at regular intervals and non-transmissive portions that do not transmit light are alternately arranged at equal pitches in the circumferential direction. When the encoder disk 124 rotates together with the shaft 28, a pulse signal is generated every time the optical sensor 125 detects a pattern arranged on the encoder disk 124. This pulse signal is output to the control unit 130 described later. The control unit 130 detects the drive amount of the paper feed roller 25, that is, the rotation amount of the paper feed roller 25 based on the pulse signal from the rotary encoder 122.

[Control unit 130]
Hereinafter, a schematic configuration of the control unit 130 (an example of the control unit of the present invention) will be described. The present invention is realized when the control unit 130 performs conveyance control according to a flowchart (see FIG. 6) described later.

  As shown in FIG. 5, the control unit 130 controls the overall operation of the multifunction machine 10. The control unit 130 is configured as a microcomputer mainly including a CPU 131, a ROM 132, a RAM 133, an EEPROM 134, and an ASIC 135. These are connected by an internal bus 137.

  The ROM 132 stores a program for the CPU 131 to control various operations including conveyance control of the multifunction machine 10. The RAM 133 is used as a storage area for temporarily recording data and signals used when the CPU 131 executes the program, or as a work area for data processing. The EEPROM 134 stores settings, flags, and the like that should be retained even after the power is turned off.

  The ASIC 135 is connected to a first drive motor 103, a second drive motor 102, and the like, and a drive circuit for controlling each motor is incorporated. When a driving signal for rotating each motor is input from the CPU 131 to a driving circuit corresponding to a predetermined motor, a driving current corresponding to the driving signal is output from the driving circuit to the corresponding motor. Rotates forward or backward at a predetermined rotational speed. That is, the control unit 130 controls the first drive motor 103 and the second drive motor 102.

  Further, a pulse signal output from the rotary encoder 122 is input to the ASIC 135. The control unit 130 calculates the rotation amount of the paper feed roller 25 based on the pulse signal from the rotary encoder 122.

  In addition, the optical sensor 111 is connected to the ASIC 135. The optical sensor 111 outputs an analog electric signal (voltage signal or current signal) corresponding to the intensity of light received by the light receiving element. The output signal is input to the control unit 130, and the control unit 130 determines whether the electrical level (voltage value or current value) is equal to or higher than a predetermined threshold value. When the input signal is greater than or equal to a predetermined threshold, it is determined as a HIGH level signal, and when it is less than the predetermined threshold, it is determined as a LOW level signal. Accordingly, the control unit 130 determines whether or not the leading edge of the recording paper has reached the detection unit 121.

  In addition, the control unit 130, based on the input signal from the optical sensor 111, determines that the leading edge of the recording paper has reached the detection unit 121, and based on the pulse signal from the rotary encoder 122, feed roller 25. Start counting the amount of rotation. The control unit 130 determines the current leading edge position of the recording paper based on the elapsed time from the above timing and the counted rotation amount of the paper feed roller 25.

  The determination of the current position of the leading edge of the recording paper by the control unit 130 is not limited to the above. For example, the control unit 130 may start counting the rotation amount of the paper feed roller 25 at the timing of starting the rotation of the paper feed roller 25. In this case, the control unit 130 can determine the current front end position of the recording sheet based on the rotation amount of the paper feed roller 25 counted from the start of rotation of the paper feed roller 25. Further, the leading end position of the current recording sheet may be determined based on the elapsed time from the rotation start timing of the sheet feeding roller 25. In these cases, the detection unit 121 is not necessary for determining the current leading edge position of the recording sheet.

[Conveyance control by control unit 130]
In the printer unit 11 configured as described above, the control unit 130 feeds the recording paper and executes a series of conveyance control for the recording paper conveyed through the conveyance path 65. Hereinafter, an example of the processing procedure of the conveyance control will be described based on the flowchart of FIG.

  When an image recording instruction (an example of a conveyance start command of the present invention) is input to the multifunction machine 10 from an external device or the operation panel 18 (see FIG. 1), the control unit 130 records an image according to the image recording instruction. The type of recording paper is determined (S10). For example, before the image recording instruction is input, the control unit 130 indicates whether the recording paper to be image-recorded placed on the paper feed tray 20 is plain paper, glossy paper, or thick paper. (Corresponding to the type information of the present invention). The information may be included in a part of the image recording instruction, or may be input by the user from the operation panel 18 or the like separately from the image recording instruction. When the information is not input, for example, the control unit 130 causes the operation panel 18 to display a message instructing to input the information.

  When the control unit 130 determines in step S10 that the recording paper is glossy paper or thick paper, the control unit 130 rotates the second drive motor 102 in the forward direction and rotates the paper feed roller 25 (S20). At this time, the third transport roller 56 is stopped. At this time, the third transport roller 56 can idle. As a result, the recording paper is conveyed toward the third roller pair 55 by the paper supply roller 25. Therefore, the recording paper can be further conveyed by the paper feed roller 25 even when the third conveyance roller 56 is not rotated when the recording paper is sandwiched between the third roller pair 55.

  Next, the control unit 130 determines whether or not the conveyed recording paper has passed the detection unit 121 (S30). This determination is made based on the level of the signal input from the optical sensor 111 as described above.

  When the control unit 130 determines that the recording sheet has passed the detection unit 121 (S30: Yes), the control unit 130 counts the driving amount of the paper feed roller 25 (S40). The count is calculated based on the pulse signal input from the rotary encoder 122 as described above.

  The control unit 130 calculates the conveyance amount from the recording sheet detection unit 121 based on the driving amount of the paper feed roller 25 from the time point of step S30. Next, the control unit 130 determines that the conveyance amount is from the position of the detection unit 121 to the position of the plane 22 (for example, a position that is a predetermined distance away from the holding position of the recording sheet by the third roller pair 55 on the downstream side in the conveyance direction). It is determined whether it is larger than the distance. The control unit 130 may determine whether or not the transport amount is greater than a distance obtained by adding a predetermined value to the distance from the position of the detection unit 121 to the position of the plane 22.

  If the transport amount is greater than the distance, the control unit 130 determines that the leading edge of the recording paper has reached the plane 22 (S50: Yes), and switches the second drive motor 102 from normal rotation to reverse rotation. Thereby, the paper feed roller 25 is stopped and the third transport roller 56 is rotated (S60). Thereafter, the recording paper is conveyed by the third roller pair 55. As described above, the processing from step S10 to step S60 is an example of the first processing mode of the present invention. In the present embodiment, the paper feed roller 25 is stopped in step S60, but the paper feed roller 25 may not be stopped in step S60. That is, in this case, until step S50 (until the leading edge of the recording paper reaches the flat surface 22), the paper feed roller 25 is driven and the third transport roller 56 is stopped, but in step S60, the paper is fed. In addition to the roller 25, the third transport roller 56 is driven.

  On the other hand, when the control unit 130 determines in step S10 that the recording paper is plain paper, the control unit 130 starts the processing from step S70. The process from step S70 to S90 is the same process as the process from step S20 to S40 described above.

  The control unit 130 calculates the conveyance amount from the detection unit 121 of the recording paper based on the driving amount of the paper feed roller 25 from the time point of step S90. Next, the control unit 130 determines whether or not the transport amount is greater than the distance from the position of the detection unit 121 to the recording paper clamping position by the third roller pair 55. The control unit 130 determines that the transport amount is a distance obtained by adding a predetermined value to the distance from the position of the detection unit 121 to the clamping position (however, a distance smaller than the distance from the position of the detection unit 121 to the position of the plane 22). ) May be determined.

  When the transport amount is greater than the distance, the control unit 130 determines that the leading edge of the recording paper has reached the recording paper clamping position by the third roller pair 55 (S100: Yes), and moves the second drive motor 102 to the second driving motor 102. Switch from forward rotation to reverse rotation. Thereby, the paper feed roller 25 is stopped and the third transport roller 56 is rotated (S110). Thereafter, the recording paper is conveyed by the third roller pair 55. As mentioned above, the process from step S10 and step S70 to step S110 is an example of the second processing mode of the present invention.

  As described above, the control unit 130 selects and executes the first processing mode or the second processing mode based on the information indicating the type of recording paper placed on the paper feed tray 20.

  The recording paper conveyed in the first processing mode or the second processing mode is conveyed by the first roller pair 58 and an image is recorded by the recording unit 24. Thereafter, the recording sheet on which the image is recorded is conveyed by the second roller pair 59 and discharged to the discharge tray 21.

[Effect of the embodiment]
In the above-described embodiment, the outer guide surface 17 </ b> A is located immediately downstream in the conveyance direction at the position where the third conveyance roller 56 is provided in the portion constituting the curved path 66 on the downstream side of the third conveyance roller 56. It is the plane 22 which goes to the straight path 67 side from, and is not curved. That is, the recording paper that has passed through the third transport roller 56 needs to be transported by changing its direction in the direction along the flat surface 22 after the leading end of the recording paper collides with the flat surface 22. When the direction is changed, a force opposite to the conveying direction that the recording sheet receives from the flat surface 22 is large. However, after the direction is once changed, the recording sheet is conveyed in a state where only the vicinity of the leading end is in contact with the flat surface 22. That is, the area where one surface of the recording paper abuts on the flat surface 22 is small. Therefore, the force in the direction opposite to the conveying direction that the recording sheet receives from the flat surface 22 is small.

  In the above-described embodiment, the recording paper is transported by the paper feed roller 25 when the direction is changed in the direction opposite to the transport direction. At this time, the roller surface of the paper supply roller 25 may slip on the surface of the recording paper. However, even when the slip occurs, the image quality of the image recorded on the recording paper by the recording unit 24 is kept good.

  The reason will be described below. In the above-described embodiment, the paper feed roller 25 is in contact with the recording paper on the inner guide surface 19A side, and the third transport roller 56 is in contact with the recording paper on the outer guide surface 17A side. 24 records an image on the outer guide surface 17A side of the recording paper. That is, the surface of the recording paper that contacts the paper feed roller 25 is the surface opposite to the surface on which the image is recorded.

  In the above-described embodiment, the recording sheet is conveyed by the third roller pair 55 after the direction change in which the force in the direction opposite to the conveyance direction is small. Therefore, the possibility that the roller surface of the third conveying roller 56 of the third roller pair 55 slips on the surface of the recording paper is low. Thereby, the image quality of the image recorded on the recording paper by the recording unit 24 can be maintained satisfactorily.

  Normally, when the recording sheet conveyed through the conveyance path 65 is a recording sheet having rigidity higher than that of plain paper, for example, a thick sheet, a force in the direction opposite to the conveying direction that the recording sheet receives from the outer guide surface 17A increases. For this reason, the phenomenon that the roller surface of the third conveying roller 56 slips on the surface of the recording sheet is likely to occur. Further, when the recording sheet transported through the transport path is a recording sheet having a special coating on the surface on which an image is recorded, for example, glossy paper, the roller surface of the third transport roller 56 deteriorates when the roller surface of the third transport roller 56 deteriorates. The contact with the surface adversely affects the coating, and the image quality of the image recorded on the recording paper may be degraded.

  On the other hand, when the recording paper transported through the transport path 65 is a recording paper with low rigidity, for example, plain paper, the possibility that the above-described slip or image quality deterioration occurs is low. Therefore, when the leading edge of the recording sheet is positioned at the recording sheet clamping position of the third roller pair 55, the recording sheet is not the third conveying roller 56 of the third roller pair 55 but the third conveying roller 56. If the paper is fed by the paper feed roller 25 on the upstream side in the transport direction, the following problems may occur. That is, in this case, since the leading edge of the recording paper is too far away from the paper supply roller 25, the conveyance direction of the recording paper may be unstable. This increases the possibility that a recording paper jam will occur in the transport path 65.

  In the above-described embodiment, the control unit 130 selects and executes the first processing mode or the second processing mode based on the type information indicating the type of recording paper. For example, when a recording sheet with high rigidity and a recording sheet with a special coating are transported through the transport path 65, the above-described slip and deterioration in image quality occur by executing the first processing mode. The possibility can be reduced. In addition, when a recording sheet with low rigidity is conveyed on the conveyance path 65, the second processing mode is executed, so that the conveyance of the recording sheet to the conveyance path 65 on the downstream side of the third roller pair 55 is as follows. This is performed by the third transport roller 56 located closer to the leading edge of the recording paper than the paper feed roller 25. As a result, the possibility of the recording paper jam as described above can be reduced.

  In the above-described embodiment, the leading edge determination unit 120 includes the detection unit 121 and the rotary encoder 122, and the control unit 130 detects by the rotary encoder 122 after the detection unit 121 detects the leading edge of the recording paper. Since the leading end position of the recording sheet is determined based on the drive amount of the paper feed roller 25, the leading end position of the recording sheet can be accurately determined.

  In the above-described embodiment, the third transport roller 56 and the paper feed roller 25 are driven by the second drive motor 102 that is a common drive source. As a result, the number of drive sources mounted on the multifunction machine 10 can be reduced. As a result, the multifunction device 10 can be reduced in size. Further, the cost of the multifunction machine 10 can be reduced.

DESCRIPTION OF SYMBOLS 10 ... MFP 20 ... paper feed tray 22 ... plane 24 ... recording part 25 ... paper feed tray 27 ... first drive transmission mechanism 55 ... third roller pair 56- ··· Third conveying roller 57 ··· Pinch roller 65 ··· Conveying path 66 ··· Curved path 67 ··· Linear path 102 ··· Second drive motor 110 ··· Drive transmission switching mechanism 115 ··· Second drive transmission mechanism 120 ... tip determination unit 121 ... detection unit 122 ... rotary encoder 130 ... control unit

Claims (4)

It is formed by an inner guide surface and an outer guide surface facing the inner guide surface. A conveyance path in which a straight path through which a sheet passing through the path is guided along the conveyance direction is disposed;
A tray on which sheets can be placed;
A feeding roller that comes into contact with the sheet placed on the tray on the inner guide surface side with respect to the conveying path, and supplies the sheet to the curved path in the conveying direction;
A driving roller that is provided on the outer guide surface side of the curved path and is rotated by a driving force transmitted thereto, and is capable of idling in a state where the driving force is not transmitted , and the inner side of the curved path on the inner guide surface side. A pair of conveying rollers configured to be driven by a driven roller provided opposite to the driving roller, and conveying the sheet supplied to the curved path by the feeding roller to the linear path;
A leading edge determination unit that determines a leading edge position of the sheet guided along the curved path;
Provided on the outer guide surface side of the straight path, and a recording unit for recording an image on a sheet;
A controller for controlling the driving of the feeding roller and the driving roller,
A sheet that is a plane from the position immediately below the conveying direction at the position where the driving roller is provided to the straight path side at a portion of the outer guide surface that forms the curved path downstream of the driving roller. Having a support,
The control unit
Based on the conveyance start command, the feeding roller is driven in a state in which no driving force is transmitted to the driving roller, and the leading edge determination unit determines that the leading edge of the sheet has reached the sheet supporting unit. An image recording apparatus having a first processing mode for starting driving the driving roller as a condition. The control unit
The leading edge determination unit stops driving the feeding roller and starts driving the driving roller on condition that the leading edge of the sheet has determined that the sheet has reached the nipping position of the conveying roller pair. A processing mode;
The image recording apparatus according to claim 1, wherein the first processing mode or the second processing mode is selected and executed based on type information indicating a type of a sheet placed on the tray. The tip determination unit is
A detection unit that is provided upstream of the conveyance roller pair in the conveyance direction and detects the leading edge of the sheet guided along the curved path;
A drive amount detection unit for detecting the drive amount of the feeding roller,
3. The image recording according to claim 1, wherein the leading end position of the sheet is determined based on a driving amount of the feeding roller detected by the driving amount detecting unit after the leading end of the sheet is detected by the detecting unit. apparatus. A driving source;
A drive transmission switching mechanism for selectively switching transmission of driving force from the driving source to the feeding roller or the driving roller;
A first drive transmission mechanism for transmitting drive from the drive transmission switching mechanism to the feeding roller;
A second drive transmission mechanism that transmits drive from the drive transmission switching mechanism to the drive roller;
4. The image recording apparatus according to claim 1, wherein the drive roller is capable of idling in a state where the drive is transmitted from the drive source to the feed roller by the first drive transmission mechanism. 5.

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