JP2014117828A - Image recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recording device capable of easily adjusting a sheet transport amount.SOLUTION: An image recording device comprises a drive transmission unit that can change a state to a first state in which paired inversion rollers are rotated inversely and paired re-transport rollers are rotated normally, a second state in which paired transport rollers, the paired inversion rollers, and paired the re-transport rollers are rotated normally, and a third state in which the paired transport rollers and the paired inversion rollers are rotated normally, and transmission of a drive force to the paired re-transport rollers is released. If a tip end of the sheet reaches the paired transport rollers (S16: yes) and it is determined that the sheet is held between the paired inversion rollers (S17: No), a first switching process for changing the state of the drive transmission unit from the first state to the second state is executed (S18). If it is determined that a rear end of the sheet passes through the paired inversion rollers (S20: Yes), a second switching process for changing the state of the drive transmission unit from the second state to the third state is executed (S21) before the rear end of the sheet reaches the paired re-transport rollers.

Description

  The present invention relates to an image recording apparatus capable of recording an image on both sides of a sheet.

  Patent Document 1 discloses an image recording apparatus that can perform image recording on both sides of a sheet. More specifically, in the image recording apparatus described in Patent Document 1, an image is recorded on the surface by a pair of PF rollers that convey a sheet on a first conveyance path in a first conveyance direction toward a recording unit, and a recording unit. A pair of SB rollers that convey the sheet in the first direction or reverse and convey it to the second conveyance path, and a pair of DX rollers that convey the sheet on the second conveyance path in the second conveyance direction toward the PF roller pair. I have.

  Here, the PF roller pair and the SB roller pair are configured to rotate in the same direction. More specifically, when a sheet is to be conveyed in the first conveyance direction by the PF roller pair, the PF roller pair and the SB roller pair rotate in the forward direction, which is rotation in a direction in which the sheet is conveyed in the first conveyance direction. On the other hand, when the sheet is to be conveyed to the second conveyance path by the SB roller pair, the PF roller pair and the SB roller pair rotate in the reverse direction, which is a rotation opposite to the forward rotation.

  As a result, when a large sheet is reversed in the second conveyance path, the sheet is pulled between the PF roller pair and the SB roller pair. Here, if the conveyance amount per unit time of the DX roller pair is smaller than the PF roller pair, the sheet may stick to the inside of the conveyance path due to the tension between the PF roller pair and the SB roller pair. Therefore, in order to solve such a problem, it is conceivable to make the conveyance amount per unit time of the DX roller pair larger than that of the PF roller pair.

JP 2012-1332 A

  However, if the conveyance amount per unit time of the DX roller pair is excessively increased, the sheet is bent between the PF roller pair and the DX roller pair. As a result, the trailing edge of the sheet that has passed through the DX roller pair may collide with the DX roller pair, and the sheet may be wrinkled. As described above, when the conveyance amounts per unit time of the PF roller pair and the DX roller pair are different, a problem may occur in the sheet conveyed through the second conveyance path. However, it is difficult to completely match the conveyance amounts per unit time of the PF roller pair and the DX roller pair.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image recording apparatus that can easily adjust the conveyance amount of a sheet.

  (1) An image recording apparatus according to an aspect of the present invention includes a first conveyance path in which a sheet is conveyed in a first conveyance direction, a branch position that branches from the first conveyance path, and the first position from the branch position. A main body formed with a second conveyance path that merges with the first conveyance path at the upstream merging position in the conveyance direction and that conveys the sheet in the second conveyance direction from the branch position toward the merging position; A forward rotation that is provided in the first conveyance path downstream from the merging position in the first conveyance direction, and that forwards the sheet on the first conveyance path in the first conveyance direction, and reverse to the forward rotation. A pair of transport rollers capable of reverse rotation, and provided in the first transport path downstream of the transport roller pair in the first transport direction and upstream of the branch position in the first transport direction, Transported by the transport roller pair A recording unit that records an image on the sheet, and a sheet that is provided in the first conveyance path downstream from the branch position in the first conveyance direction, and on which the image is recorded by the recording unit. A reversing roller pair capable of forward rotation for transporting in one transport direction and reverse rotation for transporting to the second transport path with the upstream end in the first transport direction as a tip, and a pair of reverse rollers provided in the second transport path. And a re-conveying roller pair capable of forward rotation for conveying the sheet conveyed to the second conveying path by the reversing roller pair in the second conveying direction, a driving source including one or more motors, and the driving source A first mechanism in which the reverse roller pair is reversely rotated and the re-conveying roller pair is forwardly rotated, and the conveying roller pair and the reverse roller pair are forwardly rotated. And re-feed A second state in which the roller pair is forwardly rotated, and a third state in which the transport roller pair and the reverse roller pair are forwardly rotated and the transmission of the driving force of the driving source to the re-conveying roller pair is released. A drive transmission unit capable of changing the state and a control unit are provided. The control unit determines the position of the sheet, the drive transmission unit is in the first state, the leading edge of the sheet that has passed through the second conveyance path reaches the conveyance roller pair, and the control unit A first switching process for changing the state of the drive transmission unit from the first state to the second state when it is determined in the determination process that the sheet is sandwiched between the pair of reverse rollers; and the drive transmission unit Is the second state, and when it is determined in the determination process that the trailing edge of the sheet has passed the reversing roller pair, until the trailing edge of the sheet reaches the re-conveying roller pair, A second switching process for changing the state of the drive transmission unit from the second state to the third state is executed.

  According to the above configuration, the transfer of the driving force to the re-conveying roller pair is canceled during the period until the trailing edge of the sheet passes the reversing roller pair and the re-conveying roller pair. Problems caused by the difference in the conveyance amount per unit time of the conveyance roller pair can be suppressed. “Release the transmission of the driving force of the driving source to the re-conveying roller pair” means not only that the driving force is not transmitted between the driving source and the re-conveying roller pair, but also the driving source is stopped Etc. are included.

  (2) Preferably, the drive source includes a conveyance motor capable of normal rotation and reverse rotation. The transmission mechanism forwardly rotates the transport roller pair and the reverse roller pair by one of forward rotation and reverse rotation of the transport motor, and the transport roller pair and the reverse by the other of forward rotation and reverse rotation of the transport motor. The first transmission mechanism that reversely rotates the roller pair and one of the forward rotation and the reverse rotation of the conveying motor are transmitted by an odd number of gears engaged with each other, and the other of the forward rotation and the reverse rotation of the conveying motor is an even number. And a second transmission mechanism that forwardly rotates the re-conveying roller pair. The control unit changes the state of the drive transmission unit from the first state to the second state by switching the rotation of the conveyance motor from one of forward rotation and reverse rotation to the other in the first switching process. Let

  According to the above configuration, the switching from the first state to the second state can be performed only by the control for switching the rotation direction of the motor. Note that the forward and reverse rotations of the transport motor, the forward and reverse rotations of the transport roller pair and the reverse roller pair, and the number of gears (odd number and even number) used for transmitting the driving force in the second transmission mechanism, It is not intended to limit the combination. That is, the above-mentioned “one of the forward rotation and reverse rotation of the conveyance motor (the other)” does not represent the same direction in the first transmission mechanism and the second transmission mechanism, but the rotation of the conveyance roller pair and the reverse roller pair. It only shows that the direction and the number of gears in the second transmission mechanism can be switched by switching the rotation direction of the conveying motor.

  (3) More specifically, the second transmission mechanism includes a gear train in which a plurality of gears including the adjacent first gear and second gear are meshed with each other, and the drive shaft of the re-conveying roller pair is rotated. And a sun gear that rotates in the first direction by forward rotation of the transport motor, and rotates in a second direction opposite to the first direction by reverse rotation of the transport motor, and one end side with respect to the sun gear A first arm and a second arm that are rotatably supported, and rotatably supported on the other end of the first arm and meshed with the sun gear, and the sun gear rotates in the first direction. To revolve around the sun gear in the first direction and mesh with the first gear, and by rotating the sun gear in the second direction, revolve around the sun gear in the second direction. A first pendulum gear spaced from one gear; The second arm is rotatably supported on the other end side and meshed with the sun gear, and the sun gear revolves around the sun gear in the second direction by the rotation of the sun gear in the second direction. A second pendulum gear is engaged with the second gear, revolves around the sun gear in the first direction by the rotation of the sun gear in the first direction, and is separated from the second gear.

  (4) Preferably, the transmission mechanism is capable of changing a state between a transmission state in which the rotation of the conveyance motor is transmitted to the re-conveying roller pair and a non-transmission state in which the rotation is not transmitted to the re-conveying roller pair. It further has a part. In the second switching process, the control unit changes the state of the switching unit from the transmission state to the non-transmission state in a state where the conveyance motor is rotated in the forward rotation or the reverse rotation. The state of the transmission mechanism is changed from the second state to the third state.

  (5) More specifically, the recording unit includes a carriage that is movable in a scanning direction orthogonal to the first conveyance direction, and a nozzle that is mounted on the carriage and is conveyed to the sheet conveyed through the first conveyance path. And a recording head for discharging ink. The switching unit is movable to a first position and a second position separated in the scanning direction, is not engaged with the driving gear driven by the conveying motor, and the driving gear at the first position, and A driven gear that is provided at a position that meshes with the driving gear in the second position, and that is in contact with a side surface of the driving gear and a driven gear that transmits the rotation of the driving gear to the re-conveying roller pair, and the carriage And a switching lever that moves the drive gear from the second position to the first position by being in contact with the carriage. And the said control part moves the said carriage to the position contact | abutted to the said switching lever in the said 2nd switching process, The said transmission part is the said transmission state in which the said drive gear is located in the said 2nd position Then, the drive gear changes its state to the non-transmission state located at the first position.

  According to the above configuration, there is no need to separately provide a drive source (motor) for switching the state of the switching unit, so the number of motors can be reduced.

  (6) Preferably, the control unit repeatedly executes a recording process for causing the recording unit to perform image recording intermittently in a predetermined width unit along the first conveyance direction with respect to the sheet, and the recording process. The second switching process is executed between the intervals.

  According to the above configuration, it is possible to switch the state of the switching unit without reducing the throughput of image recording.

  (7) Preferably, when the determination unit determines that the trailing edge of the sheet has passed the reversing roller pair, the control unit waits until the trailing edge of the sheet reaches the re-conveying roller pair. In the meantime, the second switching process is repeatedly executed.

  According to the said structure, the state of a switching part can be switched reliably.

  (8) Preferably, the control unit records an image on the sheet in a state in which it is determined in the determination process that the trailing edge of the sheet is located between the reversing roller pair and the re-conveying roller pair. Is completed, after the second switching process is executed, the conveyance motor is caused to alternately perform forward rotation driving and reverse rotation driving at least once.

  According to the said structure, the state of a switching part can be switched more reliably.

  (9) Preferably, the pair of re-conveying rollers includes a driving roller driven by the conveying motor, a driven roller rotating in contact with the driving roller, and rotatably supporting the driving roller on one end side. The other end side located upstream from the one end side in the second transport direction is rotatably supported with respect to the main body, and has an arm that contacts and separates the driving roller from the driven roller.

  According to the above configuration, the sheet can be conveyed in the second conveyance direction against the force of the reverse roller pulling the sheet in the second state.

  (10) As an example, the image recording apparatus is disposed in the first conveyance path, and outputs an output unit that outputs a detection signal according to the presence or absence of a sheet at the position, and the rotation amount of the conveyance motor. And a rotary encoder that outputs a pulse signal. In the determination process, the control unit determines the position of the sheet by counting the number of pulse signals acquired from the rotary encoder from the time when the detection signal is acquired from the output unit.

  (11) Preferably, the re-conveying roller pair has a larger conveying amount per unit time than the conveying roller pair.

  As a result, the sheet can be prevented from sticking to the inside of the conveyance path when the conveyance roller pair and the reverse roller pair pull each other.

  According to the present invention, the re-conveying roller pair is rotated until the trailing edge of the sheet passes the re-conveying roller pair, so that the image recording apparatus capable of conveying the inverted sheet with an appropriate conveyance amount. Can be obtained.

FIG. 1 is a perspective view of the multifunction machine 10. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of the printer unit 11. FIG. 3 is a perspective view showing the internal structure of the printer unit 11. FIG. 4 is a perspective view showing the internal structure of the printer unit 11. FIG. 5 is a plan view showing the internal structure of the printer unit 11. FIG. 6 is a schematic diagram showing the transmission relationship between the roller, belt, gear, and pulley of the drive transmission mechanism 50. FIG. 7A is a plan view schematically showing the meshing of the respective gears 51, 75, 78, 88 when the switching gear 51 is in the first position, and FIG. It is a top view which shows typically meshing | engagement of each gear 51, 75, 78, 88 at the time of 2 positions. FIG. 8 is a table for explaining the rotation direction of the recording paper 12 by the feeding roller 25 and the conveying rollers 60, 62, 45, 68 with respect to the position of the switching gear 51. FIG. 9 is a block diagram illustrating a configuration of the control unit 130. FIG. 10 is a flowchart illustrating a procedure of processing executed by the control unit 130.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. 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. The multifunction machine 10 is installed and used in the state shown in FIG. In the present embodiment, 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 front-rear direction 8 is defined as the front side (front side) where the opening 13 is formed. The left-right direction 9 is defined when the multifunction machine 10 is viewed from the front side. The three directions shown in FIG. 1 are similarly displayed in other drawings.

[Overall structure of MFP 10]
As shown in FIG. 1, the multifunction machine 10 (an example of the image recording apparatus of the present invention) includes a printer unit 11 at the bottom. The multifunction machine 10 has various functions such as a facsimile function and a print function. As a print function, it has a double-sided image recording function for recording images on both sides of the recording paper 12 (an example of the sheet of the present invention, see FIG. 2). The printer unit 11 has an opening 13 formed in the front. A feed tray 20 (see FIG. 2) and a discharge tray 21 (see FIG. 2) on which the recording paper 12 can be placed can be inserted and removed in the front-rear direction 8 from the opening 13. Note that image recording by the multifunction machine 10 is not limited to the recording paper 12. For example, the multifunction machine 10 may record an image on the label surface of a CD or DVD. In this case, the CD or DVD is placed on a thin plate-shaped media tray and inserted into the multifunction machine 10 through the opening 13 or the like.

  As shown in FIG. 2, a feeding roller 25 is provided on the upper side of the feeding tray 20. The feeding roller 25 is provided so as to be in contact with the upper surface of the recording paper 12 placed on the feeding tray 20. The feed roller 25 is rotated forward by the reverse driving force of the conveying motor 71 (see FIGS. 3 to 5). The forward rotation of the feeding roller 25 is a rotation in a direction in which the recording paper 12 is sent to the first transport path 65 and transported on the first transport path 65 in the first transport direction 15. That is, the forward rotation of the feeding roller 25 when the printer unit 11 is viewed from the direction of FIG. 2 is a clockwise rotation.

  A first transport path 65 extends from the rear end of the feed tray 20 inside the printer unit 11 (an example of the main body of the present invention). The first transport path 65 includes a curved portion and a straight portion. The first transport path 65 is partitioned by an outer guide member 18 and an inner guide member 19 that face each other with a predetermined interval. The recording paper 12 accommodated in the feeding tray 20 is conveyed so as to make a U-turn from the lower side to the upper side of the curved portion, and then conveyed along the straight portion and conveyed to the recording unit 24. The recording paper 12 on which image recording has been performed by the recording unit 24 is conveyed through the linear portion and discharged to the discharge tray 21. That is, the recording paper 12 is transported in the first transport direction 15 indicated by a one-dot chain line arrow in FIG.

  A second transport path 67 is provided inside the printer unit 11. The second conveyance path 67 branches from the first conveyance path 65 at the branch position 36 and extends so as to merge with the first conveyance path 65 at the merge position 37 upstream of the first conveyance direction 15 from the branch position 36. It is. That is, the second transport path 67 is connected to the first transport path 65 at the branch position 36 and the merge position 37. The second transport path 67 is partitioned by guide members 31 and 32 that face each other in the vertical direction 7. The recording paper 12 switched back at the branch position 36 is transported through the second transport path 67 in the second transport direction 16 (direction indicated by the two-dot chain line arrow in FIG. 2) from the branch position 36 to the merge position 37. Then, it is guided again to the first transport path 65.

[Conveying roller pair, discharge roller pair, reverse roller pair, re-conveying roller pair]
As shown in FIG. 2, the first conveyance path 65 includes a conveyance roller pair including a first conveyance roller 60 and a pinch roller 61 on the upstream side in the first conveyance direction 15 from the recording unit 24, and a recording unit 24. The discharge roller pair including the second conveyance roller 62 and the spur 63 on the downstream side in the first conveyance direction 15, and the third conveyance roller 45 and the spur 46 on the downstream side in the first conveyance direction 15 from the second conveyance roller 62. A reversing roller pair provided is provided. Further, the second transport path 67 is provided with a re-transport roller pair including a fourth transport roller 68, a driven roller 69, and an arm 70 (not shown in FIGS. 3 to 5). Each roller pair conveys the recording paper 12 by rotating with the recording paper 12 sandwiched therebetween.

  The pair of transport rollers is provided on the downstream side from the joining position 37 and on the upstream side from the recording unit 24 in the first transport direction 15. The first transport roller 60 in the present embodiment is disposed above the first transport path 65, and the recording surface of the recording paper 12 transported through the first transport path 65 (the surface on which an image is recorded by the recording unit 24). ). The first transport roller 60 is externally fitted to a rotating shaft 34 to which a driving force is applied from a transport motor 71 capable of forward rotation and reverse rotation, and rotates integrally with the shaft 34. On the other hand, the pinch roller 61 is disposed below the first conveyance path 65 so as to face the first conveyance roller 60. The pinch roller 61 rotates with the rotation of the first transport roller 60. The first conveyance roller 60 and the pinch roller 61 cooperate to sandwich the recording paper 12 and convey it in the first conveyance direction 15.

  The first transport roller 60 is rotated forward by a driving force applied from a transport motor 71 that is normally driven. Here, the forward rotation of the first transport roller 60 is a rotation in the direction in which the recording paper 12 is transported in the first transport direction 15. That is, when the printer unit 11 is viewed from the direction of FIG. 2, the forward rotation of the first conveying roller 60 is a counterclockwise rotation, and the forward rotation of the pinch roller 61 is a clockwise rotation. Hereinafter, the expression “forward rotation of the conveyance roller pair” means that the first conveyance roller 60 shown in FIG. 2 rotates counterclockwise and the pinch roller 61 rotates clockwise.

  On the other hand, the first transport roller 60 rotates in the reverse direction by being applied with a driving force from a transport motor 71 that is driven in reverse. The reverse rotation of the first transport roller 60 is a rotation in the direction in which the recording paper 12 is transported in the direction opposite to the first transport direction 15. That is, the reverse rotation of the first conveying roller 60 viewed from the direction of FIG. 2 is a clockwise rotation, and the reverse rotation of the pinch roller 61 is a counterclockwise rotation. Hereinafter, the expression “reverse rotation of the conveying roller pair” means that the first conveying roller 60 shown in FIG. 2 rotates clockwise and the pinch roller 61 rotates counterclockwise.

  The discharge roller pair is provided downstream of the recording unit 24 and upstream of the branch position 36 in the first transport direction 15. The second transport roller 62 in the present embodiment is disposed below the first transport path 65 and abuts on the back surface of the recording surface of the recording paper 12 transported through the first transport path 65. The second transport roller 62 is fitted around a shaft 64 that is rotated by a driving force applied from the transport motor 71, and rotates integrally with the shaft 64. On the other hand, the spur 63 is disposed on the upper side of the first conveyance path 65 so as to face the second conveyance roller 62. The spur 63 rotates with the rotation of the second transport roller 62. The second conveyance roller 62 and the spur 63 cooperate to sandwich the recording paper 12 and convey it in the first conveyance direction 15.

  The second transport roller 62 is rotated forward by a driving force applied from a transport motor 71 that is normally driven. Here, the forward rotation of the second transport roller 62 is a rotation in the direction in which the recording paper 12 is transported in the first transport direction 15. That is, the forward rotation of the second transport roller 62 viewed from the direction of FIG. 2 is a clockwise rotation, and the forward rotation of the spur 63 is a counterclockwise rotation. Hereinafter, the expression “forward rotation of the discharge roller pair” means that the second transport roller 62 shown in FIG. 2 rotates clockwise and the spur 63 rotates counterclockwise.

  On the other hand, the second transport roller 62 rotates in the reverse direction by being applied with a driving force from a transport motor 71 that is driven in reverse. The reverse rotation of the second transport roller 62 is a rotation in the direction in which the recording paper 12 is transported in the direction opposite to the first transport direction 15. That is, the reverse rotation of the second transport roller 62 viewed from the direction of FIG. 2 is a counterclockwise rotation, and the reverse rotation of the spur 63 is a clockwise rotation. Hereinafter, the expression “reverse rotation of the discharge roller pair” means that the second transport roller 62 shown in FIG. 2 rotates counterclockwise and the spur 63 rotates clockwise.

  The reverse roller pair is provided downstream of the branch position 36 in the first transport direction 15. The third transport roller 45 in the present embodiment is disposed below the first transport path 65 and abuts on the back surface of the recording surface of the recording paper 12 transported through the first transport path 65. The third transport roller 45 is fitted around a shaft 44 that is rotated by a driving force applied from the transport motor 71 and rotates integrally with the shaft 44. On the other hand, the spur 46 is disposed on the upper side of the first conveyance path 65 so as to face the third conveyance roller 45. The spur 46 rotates with the rotation of the third transport roller 45. The third conveyance roller 45 and the spur 46 cooperate to sandwich the recording paper 12 and convey it to the first conveyance direction 15 or the second conveyance path 67.

  The third transport roller 45 is rotated forward by a driving force applied from a transport motor 71 that is normally driven. Here, the forward rotation of the third transport roller 45 is rotation in a direction in which the recording paper 12 is transported in the first transport direction 15. That is, the forward rotation of the third conveying roller 45 viewed from the direction of FIG. 2 is a clockwise rotation, and the forward rotation of the spur 46 is a counterclockwise rotation. Hereinafter, the expression “forward rotation of the pair of reverse rollers” indicates that the third transport roller 45 shown in FIG. 2 rotates clockwise and the spur 46 rotates counterclockwise.

  On the other hand, the third conveyance roller 45 is reversely rotated by being applied with a driving force from a conveyance motor 71 that is reversely driven. The reverse rotation of the third transport roller 45 is a rotation in the direction in which the recording paper 12 is transported in the direction opposite to the first transport direction 15. That is, the reverse rotation of the third transport roller 45 viewed from the direction of FIG. 2 is a counterclockwise rotation, and the reverse rotation of the spur 46 is a clockwise rotation. Hereinafter, the expression “reverse rotation of the reverse roller pair” means that the third transport roller 45 shown in FIG. 2 rotates counterclockwise and the spur 46 rotates clockwise.

  The re-transport roller pair is provided in the second transport path 67. The fourth transport roller 68 (an example of the driving roller of the present invention) in the present embodiment is disposed below the second transport path 67. The fourth transport roller 68 is rotated by a driving force applied from a transport motor 71 capable of forward drive and reverse drive. On the other hand, the driven roller 69 is disposed on the upper side of the second conveyance path 67 so as to face the fourth conveyance roller 68. The driven roller 69 rotates with the rotation of the fourth transport roller 68. The fourth transport roller 68 and the driven roller 69 cooperate to sandwich the recording paper 12 and transport it in the second transport direction 16.

  As shown in FIG. 2, the arm 70 rotatably supports the fourth transport roller 68 at one end side thereof, and is supported rotatably at the other end side with respect to the printer unit 11. Further, the end portion on the side supported by the printer unit 11 is disposed upstream of the second conveyance direction 16 with respect to the end portion on the side supporting the fourth conveyance roller 68. As a result, the arm 70 can bring the fourth transport roller 68 into and out of contact with the driven roller 69. More specifically, the arm 70 presses the fourth transport roller 68 against the driven roller 69 when a force opposite to the second transport direction 16 is applied to the recording paper 12 sandwiched between the pair of re-transport rollers. To work.

  The fourth conveyance roller 68 rotates forward regardless of the rotation direction (forward rotation drive and reverse rotation drive) of the conveyance motor 71. Here, the forward rotation of the fourth transport roller 68 is a rotation in a direction in which the recording paper 12 is transported in the second transport direction 16. That is, the forward rotation of the fourth transport roller 68 viewed from the direction of FIG. 2 is a counterclockwise rotation, and the forward rotation of the driven roller 69 is a clockwise rotation. Hereinafter, the expression “forward rotation of the re-conveying roller pair” means that the fourth conveying roller 68 shown in FIG. 2 rotates counterclockwise and the driven roller 69 rotates clockwise.

  The re-conveying roller pair is preferably set to have a larger conveying amount per unit time than the conveying roller pair. Thereby, it can suppress that the recording paper 12 sticks to the inner side of a conveyance path. A specific method for increasing the transport amount per unit time of the re-transport roller pair is not particularly limited. For example, the diameter of the fourth transport roller 68 may be larger than the diameter of the first transport roller 60. The reduction ratio in the transmission path of the driving force from the conveyance motor 71 to the fourth conveyance roller 68 may be smaller than the reduction ratio in the transmission path of the driving force from the conveyance motor 71 to the first conveyance roller 60. .

[Recording unit 24]
As shown in FIG. 2, in the first conveyance path 65, the recording unit 24 is downstream of the first conveyance roller 60 in the first conveyance direction 15 and upstream of the second conveyance roller 62 in the first conveyance direction 15. Is provided. A platen 42 is provided below the recording unit 24 and at a position facing the recording unit 24 with the first conveyance path 65 interposed therebetween. The platen 42 supports the recording paper 12 conveyed through the first conveyance path 65. The recording unit 24 records an image on the recording paper 12 supported by the platen 42 by a known inkjet method. The recording unit 24 includes a recording head 38 in which a plurality of nozzles that eject ink droplets are formed on the recording paper 12, and a carriage 40 on which the recording head 38 is mounted.

  The carriage 40 is supported by the frame of the printer unit 11 so as to be capable of reciprocating in the left-right direction 9 (an example of the scanning direction of the present invention) orthogonal to the front-rear direction 8. The carriage 40 is connected to a carriage driving motor 53 (see FIG. 9) via a known belt mechanism. The carriage 40 is reciprocated in the left-right direction 9 when a driving force is transmitted from the carriage driving motor 53. With the recording paper 12 supported on the platen 42, the carriage 40 is reciprocated. When the carriage 40 is reciprocated, ink droplets are ejected from the recording head 38. As a result, an image is recorded on the recording paper 12 supported by the platen 42.

[First sensor 160 and second sensor 170]
As shown in FIG. 2, in the first transport path 65, the first sensor is located upstream of the first transport roller 60 in the first transport direction 15 and downstream of the merge position 37 in the first transport direction 15. 160 (an example of the output unit of the present invention) is provided. The first sensor 160 includes a shaft 161, a detector 162 that can rotate around the shaft 161, and an optical sensor 163 that includes a light emitting element and a light receiving element that receives light emitted from the light emitting element. Yes.

  One end of the detector 162 protrudes into the first conveyance path 65. When an external force is not applied to one end of the detector 162, the other end of the detector 162 enters an optical path from the light emitting element to the light receiving element of the optical sensor 163, and blocks light passing through the optical path. At this time, the optical sensor 163 outputs a low level signal (“signal whose signal level is less than the threshold”, which is an example of the second detection signal of the present invention) to the control unit 130 described later. On the other hand, when one end of the detector 162 is pushed and rotated by the downstream end of the recording paper 12 in the first conveying direction 15, the other end of the detector 162 is removed from the optical path, and light passes through the optical path. At this time, the optical sensor 163 outputs a high level signal (“signal having a signal level equal to or higher than a threshold”, which is an example of the first detection signal of the present invention) to the control unit 130. That is, the first sensor 160 outputs a detection signal corresponding to the presence or absence of the recording paper 12 at the position where the first sensor 160 is installed to the control unit 130.

  In the first conveyance path 65, a second sensor 170 is provided on the downstream side in the first conveyance direction 15 from the recording unit 24 and the second conveyance roller 62 and on the upstream side in the first conveyance direction 15 from the branch position 36. Yes. Similar to the first sensor 160, the second sensor 170 includes a shaft 171, a detector 172, and an optical sensor 173. Similar to the first sensor 160, the second sensor 170 outputs a detection signal according to the presence or absence of the recording paper 12 at the position where the second sensor 170 is installed to the control unit 130.

[Rotary encoder 73]
As shown in FIG. 2, the first transport roller 60 is provided with a rotary encoder 73 that generates a pulse signal by the rotation of the first transport roller 60. The rotary encoder 73 is provided on the shaft 34 of the first transport roller 60 and rotates with the first transport roller 60 so as to sandwich the encoder disk 74 from the thickness direction (a direction perpendicular to the paper surface of FIG. 2). And an optical sensor 72 provided. In the encoder disk 74, transmissive portions through which light is transmitted and non-transmissive portions through which light is not transmitted are alternately arranged at equal pitches in the circumferential direction. The optical sensor 72 emits light from a light emitting unit (not shown) toward the encoder disk 74, and the light passing through the encoder disk 74 is received by a light receiving unit (not shown).

  When the light emitting part of the optical sensor 72 and the transmission part of the encoder disk 74 face each other, the light output from the light emitting part is received by the light receiving part. At this time, the optical sensor 72 outputs a high level signal to the control unit 130. On the other hand, when the light emitting part of the optical sensor 72 and the non-transmissive part of the encoder disk 74 face each other, the light output from the light emitting part is not received by the light receiving part. At this time, the optical sensor 72 outputs a low level signal to the control unit 130. As a result, the encoder disk 74 is rotated (in other words, the conveying motor 71 or the first conveying roller 60 is rotated), whereby a pulse signal is output from the optical sensor 72 to the control unit 130.

[Route switching member 41]
As shown in FIG. 2, in the first conveyance path 65, the second conveyance roller 62 is downstream in the first conveyance direction 15 and the third conveyance roller 45 is upstream in the first conveyance direction 15 (that is, the branch position). 36), a path switching member 41 is provided. The path switching member 41 includes auxiliary rollers 47 and 48, a flap 49, and a shaft 87. The flap 49 extends substantially from the shaft 87 in the first conveying direction 15 and is pivotally supported by the shaft 87 so as to be rotatable. The spur-shaped auxiliary rollers 47 and 48 are rotatably supported by the flap 49. The flap 49 pivots about the shaft 87, so that the discharge posture (the posture indicated by the broken line in FIG. 2) positioned above the branch position 36 relative to the inner guide member 19 and the extended end portion 49A branch. The posture can be changed to a reverse posture (posture indicated by a solid line in FIG. 2) located below the position 36.

  The flap 49 in the normal state is in an inverted posture due to its own weight. Then, the flap 49 is rotated around the shaft 87 by being lifted by the recording sheet 12 conveyed through the first conveyance path 65, and changes its posture from the reverse posture to the discharge posture. Thereafter, the flaps 49 (specifically, the auxiliary rollers 47 and 48) contact the recording paper 12 and guide the recording paper 12. When the upstream end (that is, the rear end) of the recording paper 12 in the first conveyance direction 15 passes through the auxiliary roller 47, the flap 49 changes its posture from the discharge posture to the reverse posture due to its own weight. Thereby, the rear end of the first conveyance direction 15 of the recording paper 12 faces downward (that is, the entrance of the second conveyance path 67). When the third transport roller 45 continues to rotate forward in this state, the recording paper 12 is transported in the first transport direction 15 and discharged to the discharge tray 21. On the other hand, when the rotation of the third conveyance roller 45 is switched from the forward rotation to the reverse rotation, the recording paper 12 is guided to the second conveyance path 67 with the end on the upstream side in the first conveyance direction 15 as the leading end.

[Drive transmission mechanism 50]
As shown in FIGS. 3 to 5, the printer unit 11 is provided with a drive transmission mechanism 50 that transmits the driving force of the conveying motor 71 to each roller pair. The drive transmission mechanism 50 includes a roller pulley 76, a motor pulley 58, a first belt 77, a first drive transmission unit 26, a second drive transmission unit 27, a third drive transmission unit 33, and a fourth drive transmission unit 28. A feeding drive transmission unit 29 and a switching unit 30. The conveyance motor 71 and the drive transmission mechanism 50 are examples of the drive transmission unit of the present invention.

  As shown in FIG. 5, the roller pulley 76 is attached to the shaft 34 of the first transport roller 60 on the left side of the first transport path 65. As shown in FIGS. 3 to 5, a motor pulley 58 is attached to the rotation shaft of the conveyance motor 71 in the conveyance motor 71. The endless annular first belt 77 is stretched between a roller pulley 76 and a motor pulley 58. Thereby, the rotational driving force of the conveyance motor 71 is transmitted to the first conveyance roller 60. Specifically, as shown in FIG. 8, the first transport roller 60 rotates forward when the transport motor 71 is driven to rotate forward, and rotates reversely when the transport motor 71 is driven reversely.

[First drive transmission unit 26]
As shown in FIGS. 3 to 6, the first drive transmission unit 26 includes a left gear 52, a lower gear 80, a first pulley 81, a second pulley 82, and a second belt 83. . The left gear 52 is provided on the left side of the first conveyance path 65 on the shaft 34 of the first conveyance roller 60. The lower gear 80 meshes with the left gear 52 on the lower side of the left gear 52. The first pulley 81 is attached to the right side of the lower gear 80 and rotates coaxially and integrally with the lower gear 80. As a result, the first pulley 81 rotates in conjunction with the rotation of the first transport roller 60. The second pulley 82 is attached to the shaft 64 of the second transport roller 62. The endless second belt 83 is bridged between the first pulley 81 and the second pulley 82.

  A known one-way clutch (specifically, a needle clutch) is provided inside the second pulley 82. That is, the second pulley 82 is attached to the shaft 64 via the one-way clutch. As a result, the first drive transmission unit 26 transmits the rotational driving force of the conveying motor 71 driven in the forward direction to the second conveying roller 62, and the rotational driving force of the conveying motor 71 driven in the reverse rotation is transferred into the second conveying roller. It is not transmitted to the roller 62. That is, as shown in FIG. 8, the second transport roller 62 rotates forward by the forward driving force of the transport motor 71 transmitted by the first drive transmission unit 26.

[Third drive transmission unit 33]
As shown in FIGS. 3 to 6, the third drive transmission unit 33 includes a third pulley 84, a fourth pulley 85, and a third belt 86. The third pulley 84 is attached to the left side of the second pulley 82 on the shaft 64 and rotates coaxially and integrally with the second pulley 82. The fourth pulley 85 is attached to the shaft 44 of the third transport roller 45. The endless annular third belt 86 is bridged between the third pulley 84 and the fourth pulley 85. Thereby, the rotation of the second conveyance roller 62 is transmitted to the third conveyance roller 45 via the third belt 86. That is, as shown in FIG. 8, the third conveyance roller 45 is rotated in the normal direction of the conveyance motor 71 transmitted by the first drive transmission unit 26 and the third drive transmission unit 33 in the same manner as the second conveyance roller 62. Forward rotation by driving force.

[Second drive transmission unit 27]
As shown in FIGS. 3 to 6, the second drive transmission unit 27 includes a first gear 78, a first output gear 75, a plurality of first intermediate gears 95 meshed with each other, and a second gear 101. And a first pendulum gear mechanism 96. The first pendulum gear mechanism 96 includes a sun gear 97 that meshes with the first intermediate gear 95, a pendulum gear 98 that revolves and rotates around the sun gear 97, and an arm 102.

  The first gear 78 is provided on the right side of the first conveyance path 65 in the shaft 34 of the first conveyance roller 60. The first gear 78 is provided coaxially with the first transport roller 60 and rotates integrally with the first transport roller 60. That is, when the first transport roller 60 rotates, the first gear 78 also rotates. The rotation of the first gear 78 is transmitted to the first output gear 75 via a switching gear 51 of the switching unit 30 described later.

  The first output gear 75 meshes with the switching gear 51, the gear located on the most upstream side of the driving force transmission path of the first intermediate gear 95, and the sun gear 109 of the fourth drive transmission unit 28 described later. Has been. As shown in FIG. 7B, the first output gear 75 is meshed with the switching gear 51 located at the second position, and the rotational driving force of the first gear 78 is transmitted to rotate.

  The plurality of first intermediate gears 95 are arranged in the front-rear direction 8 in a state of being engaged with each other. In the present embodiment, an even number of first intermediate gears 95 are arranged. In FIG. 6, four first intermediate gears 95 are drawn for convenience, but it goes without saying that the number is not limited to four. The first intermediate gear 95 disposed on the most downstream side of the driving force transmission path meshes with the sun gear 97 of the first pendulum gear mechanism 96. As described above, the rotational driving force of the first gear 78 is transmitted to the sun gear 97 via the second position switching gear 51, the first output gear 75, and the plurality of first intermediate gears 95.

  The sun gear 97 is rotatably supported by the frame of the printer unit 11 or the like. One end of the arm 102 is attached to the thrust surface of the sun gear 97. As a result, the arm 102 rotates coaxially with the sun gear 97. A pendulum gear 98 is rotatably supported at the other end of the arm 102. The pendulum gear 98 is meshed with the sun gear 97. Accordingly, the pendulum gear 98 rotates while being supported by the arm 102 and revolves around the outer periphery of the sun gear 97 in the rotational direction of the sun gear 97 while meshing with the sun gear 97.

  Hereinafter, the drive transmission by the second drive transmission unit 27 will be described with reference to FIG. When the transport motor 71 is driven in reverse, the first transport roller 60 and the first gear 78 rotate clockwise. Here, between the first gear 78 and the sun gear 97, the switching gear 51, the first output gear 75, and the even number of first intermediate gears 95 are meshed with each other. That is, an even number of gears are engaged with each other between the first gear 78 and the sun gear 97. For this reason, when the 1st gear 78 rotates clockwise, the sun gear 97 rotates counterclockwise (direction of the arrow 99).

  When the sun gear 97 rotates counterclockwise, the pendulum gear 98 revolves around the sun gear 97 in the direction of the arrow 99 while rotating clockwise, and meshes with the second gear 101. The second gear 101 meshed with the pendulum gear 98 rotates counterclockwise. Here, the second gear 101 is provided at the right end of the shaft 64 of the second transport roller 62 (see FIGS. 3 to 5), and is a gear that rotates integrally with the second transport roller 62. That is, as shown in FIG. 8, when the switching gear 51 is in the second position, the second transport roller 62 rotates the transport motor 71 transmitted by the second drive transmission unit 27 in reverse by the reverse driving force. To do.

  The rotational driving force of the second transport roller 62 that rotates in reverse is transmitted to the third transport roller 45 via the third pulley 84, the third belt 86, and the fourth pulley 85. As a result, as shown in FIG. 8, the third transport roller 45 is configured such that the transport motor transmitted by the second drive transmission unit 27 and the third drive transmission unit 33 when the switching gear 51 is in the second position. Reverse rotation is caused by the reverse driving force of 71.

  On the other hand, when the transport motor 71 is driven to rotate forward, the first gear 78 rotates clockwise. The sun gear 97 rotates clockwise (arrow 100) when the rotational driving force of the first gear 78 is transmitted. As a result, the pendulum gear 98 revolves around the sun gear 97 in the direction of the arrow 100 while rotating counterclockwise, and is separated from the second gear 101. For this reason, the second drive transmission unit 27 does not transmit the normal driving force of the conveyance motor 71 to the second conveyance roller 62 and the third conveyance roller 45.

  The roller pulley 76, the motor pulley 58, the first belt 77, the first drive transmission unit 26, the second drive transmission unit 27, and the third drive transmission unit 33 configured as described above transmit the normal rotation driving force of the conveyance motor 71. The first conveying roller 60, the second conveying roller 62, and the third conveying roller 45 are rotated forward to transmit the reverse driving force of the conveying motor 71 to transmit the first conveying roller 60, the second conveying roller 62, and the third conveying roller. 4 is an example of a first transmission mechanism of the present invention that reversely rotates 45.

[Fourth drive transmission unit 28]
As shown in FIGS. 3 to 6, the fourth drive transmission unit 28 (an example of the second transmission mechanism of the present invention) includes a second pendulum gear mechanism 103, a forward meshing gear 104, a reverse meshing gear 105, and the like. The plurality of second intermediate gears 106, the third intermediate gear 107, and the third gear 108 meshed with each other. The second pendulum gear mechanism 103 includes a sun gear 109 that meshes with the first output gear 75, two pendulum gears 110 and 111 that revolve and rotate around the sun gear 109, and two arms 112 and 113. Yes.

  The sun gear 109 is rotatably supported by the frame of the printer unit 11 or the like. The sun gear 109 is driven and transmitted from the first output gear 75 of the second drive transmission unit 27 to rotate. More specifically, as shown in FIG. 7B, when the switching gear 51 in the second position and the first output gear 75 are meshed, the rotational driving force of the first gear 78 is transferred to the fourth drive. Is transmitted to the unit 28.

  One end of the arms 112 and 113 is attached to the thrust surface of the sun gear 109. Thereby, the arms 112 and 113 rotate coaxially with the sun gear 97. A pendulum gear 110 is rotatably supported on the other end of the arm 112. A pendulum gear 111 is rotatably supported on the other end of the arm 113. The pendulum gears 110 and 111 are meshed with the sun gear 109. The pendulum gear 110 rotates while being supported by the arm 112 and revolves in the rotational direction of the sun gear 109 while meshing with the sun gear 109. Similarly, the pendulum gear 111 rotates while being supported by the arm 113 and revolving in the rotational direction of the sun gear 109 while meshing with the sun gear 109.

  The pendulum gear 110 can mesh with the forward meshing gear 104 (an example of the first gear of the present invention). The pendulum gear 111 can mesh with the reverse meshing gear 105 (an example of the second gear of the present invention). The forward meshing gear 104, the reverse meshing gear 105, and the plurality of second intermediate gears 106 constitute a gear train in which adjacent gears mesh with each other. The reverse meshing gear 105 is meshed with the normal meshing gear 104. The forward meshing gear 104 is meshed with the reverse meshing gear 105 and a gear disposed on the most upstream side of the driving force transmission path of the second intermediate gear 106. That is, the forward meshing gear 104 and the reverse meshing gear 105 are adjacent to each other in the gear train.

  The second intermediate gears 106 are arranged side by side in the front-rear direction 8 in a state of being engaged with each other. In the present embodiment, an even number of second intermediate gears 106 are arranged. In FIG. 6, four second intermediate gears 106 are drawn for convenience, but it is needless to say that the number is not limited to four. The third intermediate gear 107 is provided coaxially with the gear disposed on the most downstream side of the driving force transmission path of the second intermediate gear 106. The third intermediate gear 107 rotates integrally with the second intermediate gear 106 around a shaft 79 coaxial with the second intermediate gear 106. The third intermediate gear 107 is meshed with the third gear 108. The third gear 108 is disposed coaxially with the fourth transport roller 68 and can rotate integrally with the fourth transport roller 68.

  Hereinafter, the drive transmission by the fourth drive transmission unit 28 will be described with reference to FIG. When the conveyance motor 71 is driven to rotate forward, the first conveyance roller 60 and the first gear 78 rotate counterclockwise, the switching gear 51 rotates clockwise, and the first output gear 75 rotates counterclockwise. Rotate. Then, the sun gear 109 rotates clockwise (in the direction of the arrow 114). The direction of the arrow 114 is an example of the first direction of the present invention. As a result, the pendulum gear 110 revolves around the sun gear 109 in the direction of the arrow 114 while rotating counterclockwise, and meshes with the forward meshing gear 104. On the other hand, the pendulum gear 111 revolves around the sun gear 109 in the direction of the arrow 114 while rotating counterclockwise, and is separated from the reverse meshing gear 105. The posture of the fourth drive transmission unit 28 described above is an example of a first posture of the present invention. As a result, the forward meshing gear 104 is rotated clockwise by receiving the forward driving force of the transport motor 71.

  Here, between the sun gear 109 and the third gear 108, the pendulum gear 110, the forward meshing gear 104, and the even number of second intermediate gears 106 are coupled in a row in a state of being meshed with each other. The third intermediate gear 107 is not included in the above number because it rotates integrally with the second intermediate gear 106 coaxially. From the above, the third gear 108 and the fourth transport roller 68 rotate counterclockwise as the sun gear 109 rotates clockwise. That is, as shown in FIG. 8, when the switching gear 51 is in the second position, the fourth transport roller 68 is rotated forward by the forward driving force of the transport motor 71 transmitted by the fourth drive transmission unit 28. To do. That is, the fourth drive transmission unit 28 forwardly rotates the fourth transport roller 68 by transmitting the forward driving force of the transport motor 71 with an even number of gears.

  On the other hand, when the conveying motor 71 is driven in reverse, the first conveying roller 60 and the first gear 78 rotate clockwise, the switching gear 51 rotates counterclockwise, and the first output gear 75 rotates clockwise. Rotate. Then, the sun gear 109 rotates counterclockwise (in the direction of the arrow 115). The direction of the arrow 115 is an example of the second direction of the present invention. As a result, the pendulum gear 110 revolves around the sun gear 109 in the direction of the arrow 115 while rotating clockwise, and is separated from the forward meshing gear 104. On the other hand, the pendulum gear 111 revolves around the sun gear 109 in the direction of the arrow 115 while rotating clockwise, and meshes with the reverse meshing gear 105. The posture of the fourth drive transmission unit 28 described above is an example of a second posture of the present invention. As a result, the reverse meshing gear 105 rotates counterclockwise when the forward driving force of the conveying motor 71 is transmitted.

  Here, between the sun gear 109 and the third gear 108, the pendulum gear 111, the reverse meshing gear 105, the forward meshing gear 104, and the even number of second intermediate gears 106 are meshed with each other in a row. It is connected. That is, between the sun gear 109 and the third gear 108, an odd number of gears are connected in a row with the gears engaged with each other. From the above, the third gear 108 and the fourth transport roller 68 rotate counterclockwise as the sun gear 109 rotates counterclockwise. That is, as shown in FIG. 8, when the switching gear 51 is in the second position, the fourth conveyance roller 68 rotates forward by the reverse driving force of the conveyance motor 71 transmitted by the fourth drive transmission unit 28. . That is, the fourth drive transmission unit 28 rotates the fourth transport roller 68 forward by transmitting the reverse driving force of the transport motor 71 using an odd number of gears.

[Feeding drive transmission unit 29]
As shown in FIGS. 3 to 6, the feed drive transmission unit 29 includes a second output gear 88, a fourth intermediate gear 89, a fourth belt 90, two fifth intermediate gears 91, and a shaft 93. A sixth intermediate gear 92, a third pendulum gear mechanism 120, a seventh intermediate gear 121, an eighth intermediate gear 122, a fifth belt 94, and a feeding pulley 123 coaxial with the feeding roller 25. It consists of. The third pendulum gear mechanism 120 includes a sun gear 124 that rotates integrally with the shaft 93 around the shaft 93, a pendulum gear 125 that revolves and rotates around the sun gear 124, and an arm 126.

  The second output gear 88 is meshed with the fourth intermediate gear 89. Further, as shown in FIG. 7A, the second output gear 88 is engaged with the switching gear 51 at the first position, and the rotational driving force of the first gear 78 is transmitted. In the present embodiment, an even number (specifically, two) fourth intermediate gears 89 are prepared. The gear on the downstream side of the driving force transmission path in the fourth intermediate gear 89 is arranged coaxially with the gear on the upstream side of the driving power transmission path in the two fifth intermediate gears 91 and rotates integrally therewith. To do. An endless annular fourth belt 90 is bridged between the two fifth intermediate gears 91. More specifically, the fourth belt 90 is stretched around two pulleys (not shown) that are arranged coaxially with the two fifth intermediate gears 91 and rotate integrally.

  Of the two fifth intermediate gears 91, the gear arranged on the downstream side of the driving force transmission path is meshed with the sixth intermediate gear 92. The sun gear 124 and the sixth intermediate gear 92 of the third pendulum gear mechanism 120 are both externally fitted to the shaft 93 and integrally rotate. One end of an arm 126 is attached to the thrust surface of the sun gear 124. As a result, the arm 126 rotates about the shaft 93. A pendulum gear 125 is rotatably supported at the other end of the arm 126. The pendulum gear 125 is meshed with the sun gear 124. With the configuration described above, the pendulum gear 125 rotates while being supported by the arm 126 and meshes with the sun gear 124 so that the outer periphery of the sun gear 124 revolves in the rotational direction of the sun gear 124.

  The seventh intermediate gear 121 is disposed at a position where it can mesh with the pendulum gear 125. Further, the seventh intermediate gear 121 is meshed with the eighth intermediate gear 122. The endless annular fifth belt 94 is stretched around an eighth intermediate gear 122 (specifically, a pulley that is coaxially disposed with the eighth intermediate gear 122 and rotates integrally) and a feed pulley 123. The feed roller 25 and the feed pulley 123 rotate coaxially and integrally.

  Hereinafter, the drive transmission by the feed drive transmission unit 29 will be described with reference to FIG. When the transport motor 71 is driven in reverse, the first transport roller 60 and the first gear 78 rotate clockwise. When the first gear 78 is rotated clockwise, the switching gear 51 is rotated counterclockwise, the second output gear 88 is rotated clockwise, and the fourth intermediate gear 89 is rotated counterclockwise. Two fifth intermediate gears 91 are rotated clockwise.

  When the fifth intermediate gear 91 is rotated clockwise, the sixth intermediate gear 92 and the sun gear 124 that is coaxial with the sixth intermediate gear 92 are rotated counterclockwise (in the direction of the arrow 127). When the sun gear 124 is rotated counterclockwise, the pendulum gear 125 revolves around the sun gear 124 in the direction of the arrow 127 while rotating clockwise, and meshes with the seventh intermediate gear 121. As a result, the seventh intermediate gear 121 meshed with the pendulum gear 125 rotates counterclockwise.

  When the seventh intermediate gear 121 rotates counterclockwise, the eighth intermediate gear 122 and the feeding pulley 123 rotate clockwise. Thereby, the feed roller 25 that rotates integrally with the feed pulley 123 is also rotated clockwise. That is, as shown in FIG. 8, when the switching gear 51 is in the first position, the feeding roller 25 rotates forward by the reverse driving force of the conveying motor 71 transmitted by the feeding drive transmission unit 29. As a result, the recording paper 12 placed on the feeding tray 20 and in contact with the feeding roller 25, that is, the recording paper 12 placed on the uppermost side is fed toward the first transport roller 60. The

  On the other hand, when the conveyance motor 71 is driven forward, the sun gear 124 is rotated clockwise (in the direction of the arrow 128), conversely, when the conveyance motor 71 is driven in the reverse direction. Accordingly, the pendulum gear 125 revolves around the sun gear 124 in the direction of the arrow 128 while rotating counterclockwise, and is separated from the seventh intermediate gear 121. That is, the feed drive transmission unit 29 does not transmit the normal rotation driving force of the transport motor 71 to the feed roller 25.

[Switching unit 30]
As shown in FIGS. 3 to 7, the switching unit 30 includes a switching gear 51, coil springs 56 and 57, and a switching lever 55.

  As shown in FIG. 7, the switching gear 51 (an example of the drive gear of the present invention) meshes with the first gear 78. Thereby, the switching gear 51 is rotated by the rotation driving force of the conveying motor 71 being transmitted. In addition, the switching gear 51 maintains a meshed state with the first gear 78, and the first position (see FIG. 7A) and the second position (see FIG. 7B) separated in the left-right direction 9. It is possible to move between. The first position is located on the left side of the second position. Both the first position and the second position are located on the right side of the first transport path 65.

  As shown in FIG. 7A, the switching gear 51 at the first position is meshed with the first gear 78 and the second output gear 88 and is not meshed with the first output gear 75. Thereby, the rotational driving force transmitted from the conveyance motor 71 to the switching gear 51 via the first gear 78 is transmitted to the feeding drive transmission unit 29. On the other hand, as shown in FIG. 7B, the switching gear 51 in the second position is meshed with the first gear 78 and the first output gear 75 (an example of the driven gear of the present invention). The two-output gear 88 is not meshed. Thereby, the rotational driving force transmitted from the transport motor 71 to the switching gear 51 via the first gear 78 is transmitted to the second drive transmission unit 27 and the fourth drive transmission unit 28.

  As shown in FIG. 7, a switching lever 55 that can move in the left-right direction 9 is disposed on the right side surface of the switching gear 51. The switching lever 55 protrudes upward as shown in FIG. 3 and is exposed in the movement path of the carriage 40. That is, the switching lever 55 moves in contact with the carriage 40 that moves rightward in the left-right direction 9 in FIGS. Further, a coil spring 56 is attached to the right side of the switching lever 55. The switching lever 55 and the coil spring 56 are disposed along the axial direction of the switching gear 51. One end of the coil spring 56 is attached to the right side surface of the switching lever 55, and the other end is attached to a frame (not shown) of the printer unit 11. A coil spring 57 is attached to the left side of the switching gear 51. One end of the coil spring 57 is attached to the left side surface of the switching gear 51, and the other end is attached to a frame (not shown) of the printer unit 11.

  That is, the switching lever 55 is biased from the second position side to the first position side (ie, leftward) by the coil spring 56, and the second position from the first position side via the switching gear 51 by the coil spring 57. It is biased to the side (ie rightward). The urging force of the coil spring 56 is larger than the urging force of the coil spring 57. Therefore, in a state where the carriage 40 is not in contact with the switching lever 55, the switching gear 51 is located at the first position. On the other hand, when the switching lever 55 in contact with the carriage 40 moves rightward, the switching gear 51 is released from the biasing force of the coil spring 56 and moves rightward by the biasing force of the coil spring 57.

  The switching gear 51 located at the first position is restricted from moving leftward by the biasing force of the coil spring 56 by a first stopper (not shown). Thereby, the switching gear 51 can remain in the first position. When the switching lever 55 is pushed rightward by the carriage 40 while the switching gear 51 is located at the first position, the switching gear 51 is released from the restriction by the first stopper, and is pressed by the pressing force of the carriage 40. Move from the first position to the second position (ie, to the right).

  Next, the switching gear 51 that has moved from the first position to the second position due to the contact between the carriage 40 and the switching lever is moved to the left by the biasing force of the coil spring 56 by a second stopper (not shown). It is regulated. Thereby, the switching gear 51 can remain in the second position. If the switching lever 55 is pushed further right by the carriage 40 when the switching gear 51 is in the second position, the switching gear 51 is released from the restriction by the second stopper, and the coil spring 56 is attached. The force moves from the second position to the first position (ie, to the left).

  As described above, the switching unit 30 transmits the rotation of the first conveyance roller 60 (that is, the driving force of the conveyance motor 71) to the second drive transmission unit 27 and the fourth drive transmission unit 28 or the feeding drive transmission unit 29. Whether to transmit the driving force is switched. Specifically, the switching unit 30 transmits the rotation of the first conveyance roller 60 to the second drive transmission unit 27 and the fourth drive transmission unit 28 when the switching gear 51 is located at the second position. It is not transmitted to the feeding drive transmission unit 29. On the other hand, the switching unit 30 does not transmit the rotation of the first conveying roller 60 to the second drive transmission unit 27 and the fourth drive transmission unit 28 when the switching gear 51 is located at the first position. This is transmitted to the drive transmission unit 29.

  Paying attention to the point that the driving force is transmitted to the fourth conveying roller 68, the switching unit 30 in which the switching gear 51 is arranged at the first position does not transmit the rotational driving force of the conveying motor 71 to the fourth conveying roller 68. It is a transmission state. On the other hand, the switching unit 30 in which the switching gear 51 is disposed at the second position is in a transmission state in which the rotational driving force of the conveyance motor 71 is transmitted to the fourth conveyance roller 68.

  In the drive transmission mechanism 50 configured as described above, the first conveying roller 60, the second conveying roller 62, and the third conveying roller 45 are rotated in the reverse direction, the fourth conveying roller 68 is rotated in the forward direction, and the driving force applied to the feeding roller 25 is increased. The state in which the transmission is canceled is an example of the first state of the present invention. The first state of this embodiment (the state of the rightmost column in FIG. 8) can be realized by disposing the switching gear 51 at the second position and driving the transport motor 71 in the reverse direction. The first conveying roller 60, the second conveying roller 62, the third conveying roller 45, and the fourth conveying roller 68 are rotated forward to cancel the transmission of the driving force to the feeding roller 25. It is an example of two states. The second state of the present embodiment (the state of the second row from the right in FIG. 8) can be realized by disposing the switching gear 51 at the second position and driving the transport motor 71 in the forward direction.

  The state in which the first conveying roller 60, the second conveying roller 62, and the third conveying roller 45 are rotated forward to release the transmission of the driving force to the fourth conveying roller 68 and the feeding roller 25 is the first aspect of the present invention. It is an example of 3 states. The third state of the present embodiment (the state of the leftmost column in FIG. 8) can be realized by disposing the switching gear 51 at the first position and driving the transport motor 71 in the forward direction. Furthermore, the state where the first conveying roller 60 is reversely rotated, the feeding roller 25 is rotated forward, and the transmission of the driving force to the second conveying roller 62, the third conveying roller 45, and the fourth conveying roller 68 is released. It is described as a fourth state. The fourth state (the state in the second row from the left in FIG. 8) can be realized by disposing the switching gear 51 at the first position and driving the transport motor 71 in the reverse direction.

[Control unit 130]
A control unit 130 shown in FIG. 9 controls the overall operation of the multifunction machine 10. For example, the control unit 130 controls driving of the conveyance motor 71 to rotate each roller. The control unit 130 controls the drive of the carriage drive motor 53 to move the carriage 40. As shown in FIG. 9, the control unit 130 includes a CPU 131, a ROM 132, a RAM 133, an EEPROM 134, an ASIC 135, and an internal bus 137 that connects these components to each other.

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

  A transport motor 71 and a carriage drive motor 53 are electrically connected to the ASIC 135. The ASIC 135 acquires a drive signal for rotating each motor from the CPU 131, and outputs a drive current corresponding to the drive signal to the corresponding motor. Each motor is driven to rotate forward or reversely at a predetermined rotational speed by a drive current from the ASIC 135.

  Further, the optical sensor 72 of the rotary encoder 73, the optical sensor 163 of the first sensor 160, and the optical sensor 173 of the second sensor 170 are electrically connected to the ASIC 135. The control unit 130 detects the rotation amount of each of the transport rollers 60, 62, 45 based on the pulse signal acquired from the optical sensor 72. The control unit 130 detects the position of the recording paper 12 based on detection signals from the optical sensors 163 and 173.

[Control by control unit 130]
Hereinafter, a procedure of processing for recording an image on both sides of the recording paper 12 will be described based on the flowchart of FIG. 10 is executed by the control unit 130. In FIG. 10, the procedure of the process in which the recording paper 12 switched back at the branch position 36 passes through the second conveyance path 67 and is sent again from the joining position 37 to the first conveyance path 65 will be described in detail. Is done.

  First, when an image recording instruction is input to the multifunction device 10, the control unit 130 sets the drive transmission mechanism 50 to the fourth state. That is, the control unit 130 arranges the switching gear 51 at the first position and drives the transport motor 71 in the reverse direction. Accordingly, the recording paper 12 placed on the feeding tray 20 is sent out to the first transport path 65 by the paper feed roller 25 (S11).

  Next, when the control unit 130 determines that the downstream end (that is, the leading end) of the recording paper 12 in the first conveyance direction 15 has reached the first sensor 160, the control unit 130 starts position determination processing and size determination processing. (S12). Note that the leading edge of the recording paper 12 has reached the first sensor 160 is determined by a change in the detection signal output from the first sensor 160 from a low level signal to a high level signal.

  In the position determination process, the control unit 130 counts the number of pulse signals (the number of high level signals) of the rotary encoder 73 from the time when the leading edge of the recording paper 12 reaches the first sensor 160. Then, for example, when the number of counted pulse signals reaches a threshold value (a predetermined value corresponding to the distance from the first sensor 160 to the first transport roller 60), the control unit 130 detects the leading edge of the recording paper 12. Is determined to have reached the first conveying roller 60. In the position determination process, a plurality of threshold values corresponding to the distance from the first sensor 160 to each component (for example, the third conveyance roller 45 or the fourth conveyance roller 68) are held, thereby recording paper. It can be determined that 12 tips have reached each component. Further, by counting the number of pulse signals from the time when the upstream end (that is, the rear end) of the recording paper 12 in the first conveyance direction 15 reaches the first sensor 160, the rear end of the recording paper 12 is counted. Can be determined. The counting of the pulse signal is continued until the recording paper 12 is discharged to the discharge tray 21.

  Note that the position determination process can be performed using not only the first sensor 160 but also the second sensor 170. That is, the control unit 130 holds a threshold corresponding to the distance from the second sensor 170 to each component in advance, and the rotary encoder 73 from the time when the leading edge or the trailing edge of the recording paper 12 passes through the second sensor 170. The position of the recording paper 12 can be determined by counting the number of pulse signals and comparing the counted pulse signal with a threshold value. For example, the fact that the leading edge of the recording paper 12 has reached the first transport roller 60 and that the leading edge of the recording paper 12 has reached the print start position facing the recording unit 24 are based on the time when the first sensor 160 is reached. You can judge as. On the other hand, the fact that the trailing edge of the recording paper 12 has passed through the auxiliary roller 47 of the path switching member 41 and the fact that the trailing edge of the recording paper 12 has passed through the third transport roller 45 indicate when the second sensor 170 has been reached. What is necessary is just to judge as a standard.

  Further, in the size determination process, the control unit 130 causes the trailing edge of the recording paper 12 to pass through the first sensor 160 from the time when the leading edge of the recording paper 12 reaches the first sensor 160 (that is, detection by the first sensor 160). The size of the recording paper 12 is determined based on the number of pulse signals until the signal changes from a high level signal to a low level signal. That is, it can be seen that the larger the number of pulse signals counted, the larger the size of the recording paper 12. In the size determination process, the type (A4, B5, etc.) of the recording paper 12 may be determined, or only the length of the recording paper 12 along the first transport direction 15 may be determined. Further, instead of the above-described size determination process, the user may input the size of the recording paper 12.

  Next, when it is determined that the leading edge of the recording paper 12 has reached the first conveyance roller 60, the control unit 130 switches the drive transmission mechanism 50 from the fourth state to the third state (S13). That is, the control unit 130 does not move the switching gear 51 from the first position, and switches the transport motor 71 from the reverse drive to the normal drive. As a result, the first transport roller 60 rotates forward and transports the recording paper 12 in the first transport direction 15.

  Then, the control unit 130 completes image recording on the surface of the recording paper 12 (hereinafter referred to as “front surface printing”) (S14), and the position determination process using the second sensor 170 performs the rear of the recording paper 12. If it is determined that the end has passed the auxiliary roller 47 of the path switching member 41, the drive transmission mechanism 50 is switched from the third state to the first state (S15). In other words, the control unit 130 temporarily stops the forward driving motor 71, contacts the carriage 40 with the switching lever 55, and moves the switching gear 51 from the first position to the second position. The conveyance motor 71 is driven in reverse. As a result, the recording paper 12 enters the second transport path 67 from the branch position 36 with the upstream end of the first transport direction 15 as the leading end, and is transported in the second transport direction 16 through the second transport path 67. The

  Next, the control unit 130 determines whether or not the leading edge of the recording paper 12 conveyed through the second conveyance path 67 by the position determination process using the first sensor 160 has reached the first conveyance roller 60 (S16). ). When it is determined that the leading edge of the recording paper 12 has reached the first conveyance roller 60 (S16: Yes), the control unit 130 uses the result of the size determination process to determine that the trailing edge of the recording paper 12 is the third conveyance roller. It is determined whether or not it has passed 45 (S17).

  Specifically, the control unit 130 determines the size of the recording paper 12 determined by the size determination process, and the transport distance from the third transport roller 45 through the second transport path 67 to the first transport roller 60 (hereinafter referred to as “the transport distance”). (Referred to as “threshold distance”). If the size of the recording paper 12 is equal to or greater than the threshold distance, the trailing edge of the recording paper 12 has not yet passed through the third transport roller 45 when the leading edge of the recording paper 12 reaches the first transport roller 60. (S17: No). On the other hand, if the size of the recording paper 12 is less than the threshold distance, it can be determined that the trailing edge of the recording paper 12 has passed the third transport roller 45 when the leading edge of the recording paper 12 reaches the first transport roller 60. (S17: Yes).

  When it is determined that the trailing edge of the recording paper 12 has not passed through the third conveyance roller 45 (S17: No), the control unit 130 is a process of switching the drive transmission mechanism 50 from the first state to the second state. A first switching process is executed (S18). Specifically, the control unit 130 does not move the switching gear 51 from the second position, and switches the conveyance motor 71 from the reverse rotation drive to the normal rotation drive. The skew of the recording paper 12 can be corrected by executing the first switching process after the front end of the recording paper 12 is brought into contact with the first transport roller 60 (that is, the pair of transport rollers) that rotates in reverse.

  Next, the control unit 130 executes a recording process for recording an image on the recording paper 12 (S19). Specifically, the control unit 130 conveys the recording sheet 12 to the first conveying roller 60 in a predetermined width unit along the first conveying direction 15, thereby causing the recording sheet 12 to face the area of the recording sheet 12 facing the recording unit 24. And image recording. In step S19, image recording (hereinafter referred to as “back surface printing”) is performed on the back surface of the recording paper 12 (that is, the surface opposite to the front surface printing). Further, in one process of step S19, an image is recorded only on a part of the back surface of the recording paper 12 (that is, the predetermined width described above). That is, in order to record an image on the entire back surface of the recording paper 12, it is necessary to repeatedly execute the process of step S19.

  Next, the control unit 130 determines whether or not the rear end of the recording paper 12 has passed the third conveyance roller 45 (that is, the reverse roller pair) due to the recording paper 12 being conveyed by a predetermined width in step S19. Is determined (S20). In step S20, it is determined whether or not the trailing edge of the recording paper 12 has passed through the third transport roller 45 by the following process, for example.

  First, based on the paper size determined in the size determination process, the control unit 130 records when the leading edge of the recording paper 12 reaches the first transport roller 60 (that is, when it is determined S16: Yes). A conveyance amount necessary for the rear end of the sheet 12 to pass through the third conveyance roller 45 (hereinafter referred to as “necessary conveyance amount”) can be calculated. Therefore, the control unit 130 starts counting the pulse signals of the rotary encoder 73 from the time when the leading edge of the recording paper 12 reaches the first conveyance roller 60, and the number of counted pulse signals is a number corresponding to the necessary conveyance amount. At this point, it is determined that the trailing edge of the recording paper 12 has passed through the third conveyance roller 45.

  When it is determined that the trailing edge of the recording paper 12 has passed through the third transport roller 45 (S20: Yes), the control unit 130 is a process for switching the drive transmission mechanism 50 from the second state to the third state. A switching process is executed (S21). Specifically, the controller 130 moves the switching gear 51 from the second position to the first position by bringing the carriage 40 into contact with the switching lever 55. As a result, the transmission of the driving force from the conveyance motor 71 to the fourth conveyance roller 68 is released, so that the fourth conveyance roller 68 moves along with the conveyance of the recording paper 12 in the second conveyance direction 16. It only turns around. On the other hand, when it is determined that the trailing edge of the recording paper 12 has not yet passed through the third transport roller 45 (S20: No), step S21 is skipped.

  Next, the control unit 130 determines whether or not the back side printing on the recording paper 12 is completed (S22). If the back side printing has not been completed yet (S22: No), the processes of steps S19 to S21 are executed again. That is, if it is determined that the trailing edge of the recording paper 12 has passed through the third transport roller 45 between the repeated backside printing in step S19 (S20: Yes), the second switching process is executed (S21). ). In other words, the second switching process is executed at a timing when the back side printing is not performed.

  On the other hand, when the back side printing is finished (S22: Yes), the control unit 130 determines again whether or not the rear end of the recording paper 12 has passed through the third conveyance roller 45 (S23). Since the determination method in step S23 is the same as that in step S20, description thereof is omitted. When the recording paper 12 is still nipped by the third conveyance roller 45 (S23: No), the control unit 130 determines that the first conveyance roller 60 and the recording paper 12 until the rear end of the recording paper 12 passes through the third conveyance roller 45. The recording paper 12 is conveyed to the fourth conveyance roller 68.

  If the trailing edge of the recording paper 12 has passed the third transport roller 45 (S23: Yes), the control unit 130 determines whether or not the second switching process has been executed in step S21 (S24). If the second switching process is not executed in step S21 (S24: No), the control unit 130 executes the second switching process (S25), and further performs forward / reverse rotation of the transport motor 71 (S26). On the other hand, if the second switching process is executed in step S21 (S24: Yes), steps S25 and S26 are skipped.

  Note that the forward / reverse rotation of the transport motor 71 executes at least one operation in which the transport motor 71 is driven in reverse after being driven forward, or forward driven after being driven in reverse. That's it. For example, the conveyance motor 71 repeats the operation of being driven in the reverse direction after being driven in the normal direction, and is executed five times. Further, the respective drive amounts of the forward drive and the reverse drive of the transport motor 71 are rotation amounts that are at least equal to or greater than the gap between adjacent teeth in the switching gear 51, the first output gear 75, and the second output gear 88, respectively. .

  Then, the control unit 130 drives the transport motor 71 to rotate forward until the rear end of the recording paper 12 passes through the third transport roller 45 in the first direction 15, and discharges the recording paper 12 to the discharge tray 21 (S27). ). Whether or not the trailing edge of the recording paper 12 has passed through the third conveyance roller 45 can be determined by position determination processing using the second sensor 170.

  On the other hand, when it is determined in step S17 that the trailing edge of the recording paper 12 has already passed through the third conveyance roller 45 (S17: Yes), the control unit 130 moves the drive transmission mechanism 50 from the first state to the third state. The state is switched (S28). Specifically, the control unit 130 temporarily stops the conveyance motor 71 that is driven in reverse rotation, moves the switching gear 51 from the second position to the first position, and then drives the conveyance motor 71 in the normal direction. . Next, the control unit 130 performs back side printing on the back side of the recording paper 12 (S29). The back side printing in step S29 is performed until an image is recorded on the entire recording paper 12. Then, the control unit 130 discharges the recording paper 12 to the discharge tray 21 (S30). Since this process is common to step S27, a re-explanation is omitted.

[Effect of the embodiment]
According to this embodiment, the transmission of the driving force to the re-conveying roller pair is canceled during the period until the trailing edge of the recording paper 12 passes the reversing roller pair and the re-conveying roller pair. As a result, the recording paper 12 is transported only by the transport roller pair, and the re-transport roller is only rotated. As a result, it is possible to suppress problems caused by the difference in the transport amount per unit time between the transport roller pair and the re-transport roller pair.

  Further, according to the present embodiment, the first switching process (switching from the first state to the second state) only switches the rotation direction of the transport motor 71, and the second switching process (from the second state to the third state). Switching) only moves the switching gear 51 of the switching unit 30 from the second position to the first position. In particular, when the size of the recording paper 12 is large, there is a possibility that the second switching process may be performed during the reverse side printing. Therefore, by not changing the rotation direction of the conveyance motor 71 in the second switching process, the recording paper 12 Can be prevented from being displaced.

  Further, according to the present embodiment, the first transport roller 60, the third transport roller 45, and the fourth transport roller 68 are all rotated forward by the first switching process. As a result, the first transport roller 60 attempts to transport the recording paper 12 in the first transport direction 15, the fourth transport roller 68 attempts to transport the recording paper 12 in the second transport direction 16, and the third transport roller 45 performs the recording. An attempt is made to transport the paper 12 in the first transport direction 15. Therefore, the third transport roller 45 pulls the recording paper 12 transported by the first transport roller 60 and the fourth transport roller 68 in the reverse direction. However, since the reverse conveyance force is canceled (ie, pulled) mainly between the third conveyance roller 45 and the fourth conveyance roller 68, the first conveyance roller 60 causes the recording paper 12 to be reversed. The recording paper 12 can be appropriately conveyed without being greatly affected by the third conveying roller 45 to be conveyed.

  Further, according to the present embodiment, since the second switching process is executed between the intermittently executed back surface printing (S19), the second switching process can be executed without reducing the throughput of the back surface printing. In addition, by executing the second switching process a plurality of times, switching from the second state to the third state can be reliably performed. In the example of FIG. 10, it is determined whether or not the second switching process is necessary (S20) every time one back side printing (S19) is completed, but the present invention is not limited to this. That is, the second switching process (S21) may be executed at a timing when the back side printing is completed a predetermined number of times (one or more times).

  Further, when the second switching process is executed in step S25 after the back side printing on the recording paper 12 is completed (S22: Yes), it is less necessary to prevent the recording paper 12 from being misaligned. Therefore, in this embodiment, the forward / reverse rotation of the transport motor 71 is executed in step S26, so that the switching from the second state to the third state can be performed more reliably. In the example of FIG. 10, the forward / reverse rotation of the conveyance motor 71 is executed only when the second switching process is executed after the image recording is completed, but the present invention is not limited to this. That is, regardless of the timing at which the second switching process is executed, the forward / reverse rotation of the transport motor 71 may be executed after the image recording is completed.

  Further, according to the present embodiment, the fourth conveying roller 68 is brought into contact with the driven roller 69 by the arm 70. The pivot end of the arm 70 is located upstream of the support end of the fourth transport roller 68 in the second transport direction 16. As a result, when the third transport roller 45 tries to transport the recording paper 12 in the first transport direction 15, the arm 70 rotates in the direction in which the fourth transport roller 68 is pressed against the driven roller 69. The recording paper 12 can be conveyed in the second conveyance direction 16 against the force with which the third conveyance roller 45 pulls the recording paper 12.

  Furthermore, in the present embodiment, the example in which the conveyance amount per unit time of the re-conveyance roller pair is larger than the conveyance amount per unit time of the conveyance roller pair has been described, but the present invention is not limited to this. It is very difficult to completely match the transport amount per unit time between the transport roller pair and the re-transport roller pair. In the present invention, the transport amount per unit time between the transport roller pair and the re-transport roller pair is This is particularly effective when different.

  The combination of forward drive and reverse drive of the conveyance motor 71 shown in FIG. 8 and forward rotation and reverse rotation of each roller pair is an example, and the present invention is not limited to this. In other words, the drive transmission mechanism 50 rotates the conveyance roller pair and the reverse roller pair in the forward direction by one of the normal rotation drive and the reverse rotation drive of the conveyance motor 71, and the conveyance roller by the other of the normal rotation drive and the reverse rotation drive of the conveyance motor 71. Any configuration may be used as long as the pair and the reverse roller pair can be rotated in the reverse direction and the re-conveying roller pair can be rotated in the forward direction by the rotation of the conveying motor 71 (both forward rotation and reverse rotation).

  In addition, the configuration of the fourth drive transmission unit 28 in the above embodiment is an example, and the present invention is not limited to this. For example, the pendulum gear 111 and the arm 113 may be omitted, and the pendulum gear 110 may be engaged with the forward meshing gear 104 and the reverse meshing gear 105. That is, the fourth drive transmission unit 28 transmits one rotation of the sun gear 109 in the first direction and the second direction to the drive shaft of the fourth transport roller 68 by an odd number of gears, and the other of the sun gear 109 Any configuration may be used as long as the rotation can be transmitted to the drive shaft of the fourth conveying roller 68 by an even number of gears.

DESCRIPTION OF SYMBOLS 11 ... Printer part 15 ... 1st conveyance direction 16 ... 2nd conveyance direction 24 ... Recording part 26 ... 1st drive transmission part 27 ... 2nd drive transmission part 28 ... 4th drive transmission part 30 ... switching part 33 ... 3rd drive transmission part 36 ... branch position 37 ... merge position 38 ... recording head 40 ... carriage 50 ... drive transmission mechanism 51 ... switching gear 55 ... switching lever 65 ... first transport path 67 ... second transport path 68 ... fourth transport roller 69 ... driven roller 70 ... arm 71 ...・ Conveying motor 73... Rotary encoder 130... Control unit 160.

Claims (11)

A first conveyance path in which a sheet is conveyed in a first conveyance direction; and a branching position that branches from the first conveyance path and that is upstream of the branching position in the first conveyance direction to the first conveyance path. A main body formed with a second conveyance path that is joined and a sheet is conveyed in a second conveyance direction from the branch position toward the merge position;
It is provided in the first conveyance path on the downstream side in the first conveyance direction from the merging position, and forward rotation that conveys the sheet on the first conveyance path in the first conveyance direction and in the direction opposite to the forward rotation. A pair of transport rollers capable of reverse rotation;
An image is formed on the sheet transported by the pair of transport rollers, provided in the first transport path downstream from the pair of transport rollers in the first transport direction and upstream from the branch position in the first transport direction. A recording unit for recording; and
A forward rotation that is provided in the first conveyance path on the downstream side in the first conveyance direction from the branch position and conveys the sheet on which an image is recorded by the recording unit in the first conveyance direction, and the first A pair of reversing rollers capable of reverse rotation, transported to the second transport path with the upstream end in one transport direction as a tip;
A re-conveying roller pair provided in the second conveying path and capable of forward rotation for conveying the sheet conveyed to the second conveying path by the reversing roller pair in the second conveying direction;
A first state that includes a driving source including one or more motors and a transmission mechanism that transmits the driving force of the driving source, and reversely rotates the reversing roller pair and forwardly rotates the re-conveying roller pair; A second state in which the transport roller pair and the reverse roller pair are rotated forward and the re-transport roller pair is rotated forward; and the transport roller pair and the reverse roller pair are rotated forward and the re-feed roller pair is A third state where the transmission of the driving force of the driving source is released; and a drive transmission unit capable of changing the state;
A control unit,
The control unit
A determination process for determining the position of the sheet;
In the determination process, it is determined that the drive transmission unit is in the first state, the leading edge of the sheet that has passed through the second conveyance path reaches the pair of conveyance rollers, and the sheet is sandwiched between the pair of reverse rollers. A first switching process for changing the state of the drive transmission unit from the first state to the second state when
When the drive transmission unit is in the second state and it is determined in the determination process that the trailing edge of the sheet has passed the reversing roller pair, until the trailing edge of the sheet reaches the re-conveying roller pair And a second switching process for changing the state of the drive transmission unit from the second state to the third state. The drive source includes a conveyance motor capable of normal rotation and reverse rotation,
The transmission mechanism is
The transport roller pair and the reverse roller pair are rotated forward by one of the forward rotation and reverse rotation of the transport motor, and the transport roller pair and the reverse roller pair are rotated reversely by the other of the forward rotation and reverse rotation of the transport motor. A first transmission mechanism,
By transmitting one of the forward rotation and the reverse rotation of the conveying motor with an odd number of gears engaged with each other and transmitting the other of the forward rotation and the reverse rotation of the conveying motor with an even number of gears, the re-conveying roller A second transmission mechanism that forwardly rotates the pair,
The control unit changes the state of the drive transmission unit from the first state to the second state by switching the rotation of the conveyance motor from one of forward rotation and reverse rotation to the other in the first switching process. Item 8. The image recording apparatus according to Item 1. The second transmission mechanism is
A plurality of gears including adjacent first gear and second gear are meshed with each other, and a gear train that rotates the drive shaft of the re-conveying roller pair;
A sun gear that rotates in the first direction by forward rotation of the transport motor, and rotates in a second direction opposite to the first direction by reverse rotation of the transport motor;
A first arm and a second arm, one end of which is rotatably supported with respect to the sun gear;
The other end of the first arm is rotatably supported and meshed with the sun gear, and the sun gear revolves around the sun gear in the first direction by the rotation of the sun gear in the first direction. A first pendulum gear meshed with a first gear, revolved around the sun gear in the second direction by the rotation of the sun gear in the second direction, and separated from the first gear;
The second arm is rotatably supported on the other end side and meshed with the sun gear, and the sun gear revolves around the sun gear in the second direction by the rotation of the sun gear in the second direction. A second pendulum gear meshed with a second gear, revolved around the sun gear in the first direction by the rotation of the sun gear in the first direction, and separated from the second gear; The image recording apparatus according to claim 2. The transmission mechanism further includes a switching unit capable of changing a state between a transmission state in which the rotation of the conveyance motor is transmitted to the re-conveyance roller pair and a non-transmission state in which the rotation is not transmitted to the re-conveyance roller pair. And
In the second switching process, the control unit changes the state of the switching unit from the transmission state to the non-transmission state in a state where the conveyance motor is rotated to the other of normal rotation and reverse rotation. The image recording apparatus according to claim 2 or 3, wherein the state of the transmission mechanism is changed from the second state to the third state. The recording part
A carriage movable in a scanning direction orthogonal to the first conveying direction;
A recording head mounted on the carriage and ejecting ink from nozzles onto a sheet conveyed through the first conveyance path;
The switching unit is
A drive gear that is movable to the first and second positions separated in the scanning direction and is driven by the conveying motor;
A driven gear that is provided at a position that is not meshed with the drive gear at the first position and is meshed with the drive gear at the second position, and that transmits the rotation of the drive gear to the re-conveying roller pair; ,
A switching lever that is in contact with a side surface of the drive gear and exposed in the movement path of the carriage, and moves the drive gear from the second position to the first position by being in contact with the carriage. And
The control unit moves the carriage to a position in contact with the switching lever in the second switching process, thereby moving the switching unit from the transmission state in which the drive gear is positioned at the second position. The image recording apparatus according to claim 4, wherein the driving gear changes its state to the non-transmission state located at the first position.   The control unit repeatedly executes a recording process for causing the recording unit to perform image recording intermittently in a predetermined width unit along the first conveyance direction with respect to the sheet, and the second process is performed between the recording processes. The image recording apparatus according to claim 5, wherein the switching process is executed.   When the determination processing determines that the trailing edge of the sheet has passed the reversing roller pair, the control unit performs the second time until the trailing edge of the sheet reaches the re-conveying roller pair. The image recording apparatus according to claim 6, wherein the switching process is repeatedly executed.   When the image recording on the sheet is finished in the state where it is determined in the determination process that the trailing edge of the sheet is located between the reverse roller pair and the re-conveying roller pair, 8. The image recording apparatus according to claim 5, wherein after the second switching process is executed, the conveyance motor is caused to alternately perform forward rotation and reverse rotation at least once. The re-conveying roller pair is
A driving roller driven by the conveying motor;
A driven roller rotating in contact with the drive roller;
The drive roller is rotatably supported at one end side, and the other end located upstream from the one end side in the second transport direction is supported rotatably with respect to the main body, and the drive roller is supported by the driven roller. The image recording apparatus according to claim 2, further comprising an arm that is brought into contact with and separated from the arm. An output unit that is disposed in the first conveyance path and outputs a detection signal according to the presence or absence of a sheet at the position;
A rotary encoder that outputs a pulse signal indicating the rotation amount of the transport motor, and
The control unit determines the position of the sheet by counting the number of pulse signals acquired from the rotary encoder from the time when the detection signal is acquired from the output unit in the determination process. An image recording apparatus according to any one of the above.   The image recording apparatus according to claim 1, wherein the re-conveying roller pair has a larger conveyance amount per unit time than the conveying roller pair.

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