Media transport device and media transport method

Abstract

To properly return a succeeding medium following a preceding medium to a placing part side when media placed in a stacked state on a placing part are conveyed one by one.SOLUTION: There is provided a medium transport device 1 including: a feeding roller 251; a separation roller 252 that pinches a medium P together with the feeding roller 251 and separates a plurality of overlapping media P; a drive unit 210 that generates a driving force; and a one-way clutch unit 205 that is provided in a transmission path that transmits the driving force to the feeding roller 251. The one-way clutch unit 205 can be switched between an allowable state in which the feeding roller 251 is allowed to rotate in a rotational direction R2b that moves the medium P in a reverse feeding direction F2, and a restricted state in which this is not allowed, and the separation roller 252 is configured to be able to be rotated in a rotational direction R3b in which the one-way clutch unit 205 is set to the allowable state and the medium P moves in the reverse feeding direction F2.SELECTED DRAWING: Figure 11

Description

Technical Field

[0004] , , , , , ,

[0001] The present invention relates to a medium conveyance device and a medium conveyance method.

Background Art

[0002] Conventionally, a medium conveyance device has been used that can stack a plurality of media on a placement unit and can feed the stacked media one by one. Among such medium conveyance devices, there is a configuration in which a medium double-feed prevention operation is performed to return a subsequent medium following a preceding medium to the placement unit side. For example, Patent Document 1 discloses an image forming apparatus including a feed roller that feeds a medium, a motor, an electromagnetic clutch that turns on and off the transmission of driving force from the motor to the feed roller, and a retard roller that is provided at a position facing the feed roller and returns a subsequent medium following a preceding medium to the placement unit side.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0005] To solve the above problems, the media transport device of the present invention comprises: a placement section on which a medium is placed; a feeding roller for feeding the medium from the placement section in the feeding direction; a separation roller that is rotatable in a rotational direction in which the medium moves toward the placement section and in a reverse feeding direction opposite to the feeding direction, and which, together with the feeding roller, grips the medium and separates multiple stacked sheets of the medium; and a drive mechanism for driving the feeding roller and the separation roller, wherein the drive mechanism comprises a drive unit that generates a driving force and a unit that transmits the driving force to the feeding roller. The transmission path includes a one-way clutch section, the one-way clutch section being switchable between an allowable state that allows the feeding roller to rotate in the rotational direction that moves the medium in the reverse feeding direction and a restrictive state that allows the feeding roller to rotate only in the rotational direction that moves the medium in the feeding direction, and the drive mechanism section being configured to set the one-way clutch section to the allowable state and rotate the separation roller in the rotational direction that moves the medium in the reverse feeding direction.

[0006] Furthermore, the media transport method of the present invention, which solves the above problems, comprises: a mounting section on which a medium is placed; a feeding roller for feeding the medium from the mounting section in the feeding direction; a separation roller that is rotatable in a rotational direction in which the medium moves toward the mounting section and in a reverse feeding direction opposite to the feeding direction, and which, together with the feeding roller, grips the medium and separates multiple stacked sheets of the medium; a drive mechanism for driving the feeding roller and the separation roller; a drive unit for generating a driving force; and a transmission path provided in the transmission path for transmitting the driving force to the feeding roller, which allows the feeding roller to rotate in a rotational direction that moves the medium in the reverse feeding direction. A media conveying method for a media conveying device, comprising a one-way clutch unit switchable between an allowable state and a restrictive state that allows the feeding roller to rotate only in the rotational direction that moves the media in the feeding direction, characterized in that the method includes: a feeding step of feeding the media in the feeding direction by clamping the media between the feeding roller and the separation roller; and a subsequent media return step of returning the subsequent media from the media following the preceding media conveyed in the feeding step back in the reverse feeding direction by setting the one-way clutch unit to the allowable state and rotating the separation roller in the rotational direction that moves the media in the reverse feeding direction. [Brief explanation of the drawing]

[0007] [Figure 1] A front view showing the internal configuration of a printer according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is a plan view showing the drive mechanism of the printer, representing the state in which the one-way clutch is in a restricted state. [Figure 3] Figure 1 is a plan view showing the drive mechanism of the printer, representing the state in which the one-way clutch is in an acceptable condition. [Figure 4] Figure 1 is a perspective view showing the drive mechanism of the printer, representing the state in which the one-way clutch is in a restricted state. [Figure 5] Figure 1 is a perspective view showing the drive mechanism of the printer, representing the state in which the one-way clutch is in an acceptable condition. [Figure 6] Block diagram of the printer's drive mechanism shown in Figure 1. [Figure 7] Figure 1 is a perspective view showing the one-way clutch section of the printer, representing the state in which the one-way clutch section is in a restricted state. [Figure 8] Figure 1 is a perspective view showing the one-way clutch section of the printer, representing the one-way clutch section in an acceptable state. [Figure 9] Figures 7 and 8 are perspective views showing the star ratchet of the one-way clutch section of the printer. [Figure 10] Figures 7 and 8 are perspective views showing the locking mechanism of the one-way clutch section of the printer. [Figure 11] A schematic diagram illustrating the feeding operation (media double-feed suppression operation) as a media transport method that can be performed with the printer shown in Figure 1. [Figure 12] A flowchart of the feeding operation (media double-feed suppression operation) as a media transport method that can be performed with the printer shown in Figure 1. [Figure 13] A block diagram of the drive mechanism of a printer according to Embodiment 2 of the present invention. [Figure 14] A block diagram of the drive mechanism of a printer according to Embodiment 3 of the present invention. [Modes for carrying out the invention]

[0008] The present invention will be described in general terms below. A media transport device according to a first aspect of the present invention comprises: a mounting section on which media is placed; a feeding roller for feeding the media from the mounting section in the feeding direction; a separation roller that is rotatable in a rotational direction in which the media moves toward the mounting section and in a reverse feeding direction opposite to the feeding direction, and which, together with the feeding roller, grips the media and separates multiple stacked media; and a drive mechanism for driving the feeding roller and the separation roller, wherein the drive mechanism comprises a drive unit for generating a driving force and a transmission unit for transmitting the driving force to the feeding roller. The device has a one-way clutch section provided in the delivery path, the one-way clutch section being switchable between an allowable state that allows the feeding roller to rotate in a rotational direction that moves the medium in the reverse feeding direction and a restrictive state that allows the feeding roller to rotate only in a rotational direction that moves the medium in the feeding direction, and the drive mechanism is configured to set the one-way clutch section to the allowable state and rotate the separation roller in a rotational direction that moves the medium in the reverse feeding direction.

[0009] According to this embodiment, a one-way clutch is provided that can be switched between an allowable state, which permits the feeding roller to rotate in the rotational direction that moves the medium in the reverse feeding direction, and a restrictive state, which permits the feeding roller to rotate only in the rotational direction that moves the medium in the feeding direction. As a result, it is possible to appropriately return the subsequent medium to the mounting section while suppressing the subsequent medium from being forcefully thrown towards the mounting section after the preceding medium has been released from the clamping position between the feeding roller and the separation roller.

[0010] The medium conveyance device according to the second aspect of the present invention, in the first aspect, includes a conveyance roller provided upstream of the feeding roller in the feeding direction and configured to convey the medium from the placement portion toward the feeding roller. The drive mechanism unit has a switching unit configured to switch the conveyance roller between a contact state in which the conveyance roller contacts the medium and a separation state in which the conveyance roller is separated from the medium, and is capable of transmitting the driving force to the conveyance roller. The one-way clutch unit is switched between the restricted state and the permitted state by the switching operation between the contact state and the separation state of the switching unit.

[0011] According to this aspect, the drive mechanism unit has a switching unit configured to switch the conveyance roller between a contact state in which the conveyance roller contacts the medium and a separation state in which the conveyance roller is separated from the medium, and is capable of transmitting the driving force to the conveyance roller. The one-way clutch unit is switched between the restricted state and the permitted state by the switching operation between the contact state and the separation state of the switching unit. That is, the state of the one-way clutch unit can be switched using the power for switching the state of the conveyance roller. Therefore, the device configuration can be simplified.

[0012] The medium conveyance device according to the third aspect of the present invention, in the second aspect, is characterized in that the drive mechanism unit sets the one-way clutch unit in the restricted state when the switching unit sets the conveyance roller in the contact state, and sets the one-way clutch unit in the permitted state when the switching unit sets the conveyance roller in the separation state.

[0013] According to this aspect, the drive mechanism unit sets the one-way clutch unit in the restricted state when the switching unit sets the conveyance roller in the contact state, and sets the one-way clutch unit in the permitted state when the switching unit sets the conveyance roller in the separation state. Therefore, when returning the subsequent medium following the preceding medium to the placement portion side, by setting the conveyance roller in the separation state, it is possible to suppress the occurrence of jams and skews caused by the leading end of the subsequent medium in the reverse feeding direction being caught by the conveyance roller.

[0014] In the medium conveyance device according to the fourth aspect of the present invention, in any one of the first to third aspects, the one-way clutch portion has a star ratchet.

[0015] According to this aspect, the one-way clutch portion has a star ratchet. By adopting such a configuration, the drive mechanism portion can be miniaturized, and thus the device can be miniaturized.

[0016] In the medium conveyance device according to the fifth aspect of the present invention, in any one of the first to fourth aspects, a skew correction portion is provided downstream of the feed roller in the feed direction, abuts on the medium, and corrects the skew of the medium. When the medium fed by the feed roller abuts on the skew correction portion, the drive mechanism portion sets the one-way clutch portion in the restricted state and cuts off the transmission of the driving force to the feed roller.

[0017] According to this aspect, when the medium fed by the feed roller abuts on the skew correction portion, the drive mechanism portion sets the one-way clutch portion in the restricted state and cuts off the transmission of the driving force to the feed roller. By adopting such a configuration, it is possible to suppress the occurrence of damage to the preceding medium or jamming caused by the continuous application of a feeding force in the feeding direction to the preceding medium after the preceding medium abuts on the skew correction portion.

[0018] A medium conveying device according to a sixth aspect of the present invention, in the fifth aspect, comprises a conveying roller provided upstream of the feeding roller in the feeding direction and conveying the medium from the above-described mounting section toward the feeding roller, the drive mechanism section has a switching section that switches the conveying roller between a contact state in contact with the medium and a separated state separated from the medium, and is capable of transmitting the driving force to the conveying roller, the skew correction section has a pair of conveying rollers that convey the medium, and the switching section switches the conveying roller from the contact state to the separated state when the medium, whose skew has been corrected by the skew correction section, is conveyed by the pair of conveying rollers.

[0019] According to this embodiment, the switching unit switches the transport rollers from a contact state to a separated state when the medium, whose skew has been corrected by the skew correction unit, is being transported by the transport roller pair. In other words, when the medium, whose skew has been corrected, is being transported by the transport roller pair, the transport rollers are not used to transport the medium. In this way, the transport load can be reduced by reducing the number of transport units that are involved in transporting the medium.

[0020] A medium transport device according to a seventh aspect of the present invention, in a fifth or sixth aspect, comprises a recording unit provided downstream of the skew correction unit in the feeding direction for recording on the medium, wherein the drive mechanism unit continues to transmit the driving force to the feeding roller until the rear end of the medium being recorded on by the recording unit in the feeding direction leaves the clamping position between the feeding roller and the separation roller.

[0021] If the transmission of driving force to the feed roller ceases before the medium leaves the clamping position between the feed roller and the separation roller while recording is in progress by the recording unit, the transport distance per unit time may change abruptly, potentially leading to a decrease in recording quality. However, according to this embodiment, the drive mechanism continues to transmit driving force to the feed roller until the rear end of the medium being recorded by the recording unit leaves the clamping position between the feed roller and the separation roller. Therefore, it is possible to suppress abrupt changes in the transport distance per unit time while recording is in progress by the recording unit, thereby suppressing a decrease in recording quality.

[0022] A media transport method according to an eighth aspect of the present invention comprises: a mounting section on which media is placed; a feeding roller for feeding the media from the mounting section in the feeding direction; a separation roller that is rotatable in a rotational direction in which the media moves toward the mounting section and in a reverse feeding direction opposite to the feeding direction, and which, together with the feeding roller, grips the media and separates multiple stacked media; a drive mechanism for driving the feeding roller and the separation roller; a drive unit for generating a driving force; and a tolerance provided in a transmission path for transmitting the driving force to the feeding roller, which allows the feeding roller to rotate in a rotational direction that moves the media in the reverse feeding direction. A media conveying method for a media conveying device, comprising a state and a restricting state that allows the feeding roller to rotate only in the rotational direction that moves the media in the feeding direction, characterized in that the method includes: a feeding step of feeding the media in the feeding direction by clamping the media between the feeding roller and the separation roller; and a subsequent media return step of returning the subsequent media from the media following the preceding media conveyed in the feeding step back in the reverse feeding direction by setting the one-way clutch to the allowable state and rotating the separation roller in the rotational direction that moves the media in the reverse feeding direction.

[0023] According to this embodiment, the system is equipped with a one-way clutch that can switch between an allowable state, which allows the feeding roller to rotate in the direction that moves the medium in the reverse feeding direction, and a restrictive state, which allows the feeding roller to rotate only in the direction that moves the medium in the feeding direction. As a medium double-feed suppression operation, the one-way clutch is set to the allowable state, and the separation roller is rotated in the direction that moves the medium in the reverse feeding direction, thereby executing a subsequent medium return process that returns the subsequent medium to the reverse feeding direction. This prevents the subsequent medium from being forcefully thrown towards the mounting section after the preceding medium has released from the clamping position between the feeding roller and the separation roller, while appropriately returning the subsequent medium following the preceding medium to the mounting section.

[0024] [Example 1] The present invention will now be described in detail. First, an inkjet printer 1 of Embodiment 1, which is both a media transport device and a recording device of the present invention, will be described. Hereinafter, the inkjet printer 1 will be abbreviated as printer 1. In each figure, the XYZ coordinate system is a Cartesian coordinate system, and the Y axis direction is the direction that intersects with the transport direction of the medium P, i.e., the medium width direction, and also the device depth direction. Of the Y axis directions, the +Y direction is the direction from the front of the device to the back of the device, and the -Y direction is the direction from the back of the device to the front of the device.

[0025] The X-axis direction is the width direction of the device, with +X being the left and -X being the right when viewed from the operator of printer 1. The Z-axis direction is the vertical direction, i.e., the height direction of the device, with +Z being the upward direction and -Z being the downward direction. In the following, the direction in which the medium P is fed will be referred to as "downstream," and the opposite direction as "upstream." In each figure, the medium transport path is shown by a dashed line. In printer 1, the medium P is transported through the medium transport path shown by the dashed line.

[0026] As shown in Figure 1, the printer 1 comprises a housing 16 of the main body 2 and a door 17 that can rotate around an unshown axis extending in the Z-axis direction relative to the housing 16. The printer 1 also has a first media cassette 3 at the bottom of the main body 2 for storing media P such as print paper, and is configured to allow the connection of an expansion unit 6 to the lower side of the main body 2. When the expansion unit 6 is connected, the second media cassette 4 and the third media cassette 5 are located below the first media cassette 3. The media P sent from each media cassette is transported within the printer 1 along the media transport path shown by the dashed line.

[0027] Each media cassette is provided with a pick roller that feeds the contained media P in the -X direction. Pick rollers 21, 22, and 23 are provided for the first media cassette 3, the second media cassette 4, and the third media cassette 5, respectively. Each media cassette is also provided with a pair of feed rollers that feed the media P fed in the -X direction diagonally upward. Feed roller pairs 25, 26, and 27 are provided for the first media cassette 3, the second media cassette 4, and the third media cassette 5, respectively. In the following, unless otherwise specified, a "roller pair" consists of a drive roller driven by the motor 210 described later and a driven roller that rotates in contact with the drive roller.

[0028] The media P dispensed from the third media cassette 5 is sent to the reversing roller 39 by the transport roller pair 29, 28. Similarly, the media P dispensed from the second media cassette 4 is sent to the reversing roller 39 by the transport roller pair 28. The media P is then gripped between the reversing roller 39 and the driven roller 40 and sent to the transport roller pair 31. The media P dispensed from the first media cassette 3 is sent to the transport roller pair 31 without passing through the reversing roller 39. Here, the transport roller pair 31 acts as a skew correction unit. The supply roller 19 and separation roller 20 located near the reversing roller 39 are a roller pair that dispenses media P from a supply tray (not shown).

[0029] The medium P, which receives the feeding force from the transport roller pair 31, is transported between the line head 51, which is an example of a recording unit, and the transport belt 13, that is, to the recording position facing the line head 51. In the following, the medium transport path from the transport roller pair 31 to the transport roller pair 32 will be referred to as the recording transport path T1.

[0030] The line head 51 constitutes the head unit 50. The line head 51 performs recording by ejecting ink, which is an example of a liquid, onto the surface of the medium P. The line head 51 is an ink ejection head configured such that the nozzles that eject the ink cover the entire area in the width direction of the medium, and is configured as an ink ejection head that can record over the entire width of the medium without moving in the width direction of the medium. However, the ink ejection head is not limited to this, and may also be a type that is mounted on a carriage and ejects ink while moving in the width direction of the medium. Furthermore, it is also possible to use a recording unit other than an ink ejection head, such as a thermal transfer recording unit.

[0031] Printer 1 is equipped with ink storage units 61, 62, 63, and 64, which serve as liquid storage units. Ink ejected from the line head 51 is supplied to the line head 51 from each ink storage unit via tubes (not shown). Each ink storage unit is detachable. Printer 1 is also equipped with a waste liquid storage unit 11 for storing waste ink ejected from the line head 51 toward a flushing cap (not shown) for maintenance purposes.

[0032] The conveyor belt 13 is an endless belt that is wrapped around pulleys 14 and 15, and rotates when at least one of the pulleys 14 and 15 is driven by a motor (not shown). The medium P is transported at a position facing the line head 51 while being attracted to the belt surface of the conveyor belt 13. A known attraction method such as an air suction method or an electrostatic attraction method can be used to attract the medium P to the conveyor belt 13.

[0033] The recording transport path T1, which passes opposite the line head 51, is configured to transport the medium P upwards, forming an angle with respect to the horizontal and vertical directions. This upward transport direction includes the -X and +Z components in Figure 1, and this configuration allows for the suppression of the horizontal dimensions of the printer 1.

[0034] The medium P, on which the first surface has been recorded by the line head 51, is further propelled upward by the transport roller pair 32 located downstream of the transport belt 13. A flap 41 is provided downstream of the transport roller pair 32, and this flap 41 switches the transport direction of the medium P. If the medium P is to be discharged as is, the transport path of the medium P is switched by the flap 41 to head towards the upper transport roller pair 35, and the medium P is discharged towards the discharge tray 8 by the transport roller pair 35.

[0035] When recording is to be performed on a second surface opposite to the first surface of the medium P, the transport direction of the medium P is directed towards the branching position K1 by the flap 41. The medium P then passes through the branching position K1 and enters the switchback path T2. In this embodiment, the switchback path T2 is the medium transport path above the branching position K1. The switchback path T2 is provided with transport roller pairs 36 and 37. Once the medium P enters the switchback path T2, it is transported upward by the transport roller pairs 36 and 37, and when the rear edge of the medium P passes the branching position K1, the rotation direction of the transport roller pairs 36 and 37 is switched, thereby transporting the medium P downward. Note that "upward direction" does not mean only the vertically upward direction, but also includes a vector component in the vertically upward direction, and "downward direction" does not mean only the vertically downward direction, but also includes a vector component in the vertically downward direction.

[0036] A reversal path T3 is connected to the switchback path T2. In this embodiment, the reversal path T3 is the medium transport path from the branching point K1, through the transport roller pair 33 and 34, and the reversal roller 39, to the merging point S1. The medium P transported downward from the branching point K1 receives a feeding force from the transport roller pair 33 and 34, reaches the reversal roller 39, is curved and reversed by the reversal roller 39, and is sent towards the transport roller pair 31.

[0037] The medium P, transported by the transport roller pair 31 and then sent to a position facing the line head 51 again, has its second side facing the line head 51, opposite to the first side on which recording has already been done. This makes it possible for the line head 51 to record on the second side of the medium P. Here, the medium transport path from the first medium cassette 3 to the transport roller pair 31 is referred to as the supply path T0.

[0038] Next, with reference to Figure 1, as well as Figures 2 to 12, the drive mechanism 100, which is the main part of the printer 1 of this embodiment, will be described. The drive mechanism 100A of this embodiment, as the drive mechanism 100, is a mechanism that drives and changes the position of each roller in the area in which the medium P placed on the first medium cassette 3, which is the placement area on which the medium P is placed, is transported to the recording position by the line head 51. As shown in Figure 1, in this embodiment, the distance from the first medium cassette 3 to the position opposite the line head 51, which is the recording position, is short. Therefore, when transporting the medium P from the first medium cassette 3 to the recording position, the medium P is transported simultaneously by multiple transport parts, including the pick roller 21, the feed roller pair 25, the transport roller pair 31, and the transport belt 13. The present invention makes it possible to solve the problems caused by the simultaneous transport of the medium P by multiple transport parts in a small medium transport device, for example.

[0039] As shown in Figure 6 and other figures, the drive mechanism 100A of this embodiment is equipped with a pair of feeding rollers 25. Here, the pair of feeding rollers 25 includes a feeding roller 251 that feeds the medium P from the first medium cassette 3 in the feeding direction F1 shown in Figure 1, and a separation roller 252 that, together with the feeding roller 251, grips the medium P and separates multiple stacked medium P. The feeding roller 251 is rotatable by the driving force of the motor 210 in the rotation direction R2a, which is the rotation direction in which the medium P moves in the feeding direction F1, as shown in the second figure from the left in Figure 11. The separation roller 252 is rotatable by the driving force of the motor 210 in the rotation direction R3b, which is the direction in which the medium P moves toward the first medium cassette 3 and is the opposite of the feeding direction F1, as shown in the rightmost figure in Figure 11. However, the separation roller 252 is equipped with a torque limiter, and when the upper limit of the torque limiter is exceeded, the separation roller 252 will no longer move in accordance with the rotation of the rotating shaft 217. As shown in the second figure from the left in Figure 11, the configuration is such that when the feed roller 251 rotates in the rotation direction R2a, the upper limit of the torque limiter is exceeded, and the separation roller 252 rotates in the rotation direction R3a in accordance with the rotation of the feed roller 251 in the rotation direction R2a.

[0040] As shown in Figures 6 and 11, the drive mechanism 100A of this embodiment has, in addition to the feed roller pair 25, a pick roller 21 which is provided upstream of the feed roller 251 in the feed direction F1 and serves as a transport roller that transports the medium P from the first medium cassette 3 toward the feed roller 251. Furthermore, as shown in Figure 11, the drive mechanism 100A of this embodiment has a resist roller 311 and a driven roller 312 which constitute a transport roller pair 31 that also serves as a skew correction unit. Here, the pick roller 21 is rotatable by the driving force of the motor 210 in the rotation direction R1, which is the rotation direction in which the medium P moves in the feed direction F1, as shown in the second figure from the left in Figure 11. The resist roller 311 is rotatable by the driving force of the motor 210 in the rotation direction R5, which is the rotation direction in which the medium P moves in the feed direction F1, as shown in the fourth figure from the left in Figure 11.

[0041] Referring to Figure 6, in the drive mechanism 100A of this embodiment, when the motor 210 is turned on, the gear 211 attached to the rotating shaft 216 rotates, and the rotating shaft 216 also rotates in conjunction with the rotation of the gear 211. Gears 209 and 212 are attached to the rotating shaft 216, and gears 209 and 212 also rotate in conjunction with the rotation of the rotating shaft 216. However, gear 209 has a clutch C, and by turning off the clutch C, it is possible to prevent gear 209 from rotating even when the rotating shaft 216 is rotating.

[0042] Gear 212 is positioned to mesh with gear 213, which is attached to the rotating shaft 217 of the separating roller 252. When gear 212 rotates, gear 213 also rotates, and furthermore, the rotating shaft 217 and the separating roller 252 also rotate. The direction of rotation of the rotating shaft 217 when the motor 210 is turned on is rotation direction R4 in Figure 11. As shown in the rightmost figure of Figure 11, the rotation direction R4 of the rotating shaft 217 corresponds to the rotation direction R3b of the separating roller 252.

[0043] As described above, the separation roller 252 is equipped with a torque limiter. The torque limiter in the drive mechanism 100A of this embodiment houses a coil spring inside. When the rotating shaft 217 rotates in the rotational direction R4, the separation roller 252 rotates together in the rotational direction R3b. However, when an external force is applied to the separation roller 252 and this external force exceeds the upper limit of the torque limiter, the coil spring inside the torque limiter ceases to function effectively. That is, when the feed roller 251 rotates in the rotational direction R2a due to the driving force of the motor 210, the torque limit is exceeded, causing the separation roller 252 to rotate in the rotational direction R3a. However, when the external force is removed, the coil spring springs back to return to its original shape, and the separation roller 252 rotates in the rotational direction R3b.

[0044] When the coil spring of the separation roller 252 springs back while the medium P is held between the feed roller 251 and the separation roller 252, the medium P moves in the reverse feed direction F2, which is opposite to the feed direction F1. When this happens, the recording on the medium P being recorded may become distorted, and the accuracy of skew correction may decrease. Therefore, in the drive mechanism 100A of this embodiment, separate transport is performed using the feed roller pair 25 together with the transport roller pair 31 located downstream in the feed direction F1 until the rear end of the medium P being recorded passes the separation roller 252, thereby suppressing recording disturbances caused by the springback of the torque limiter. When transporting multiple mediums P, there is a risk that the trailing medium P2 may be fed continuously with the preceding medium P1, so the trailing medium P2 is fed only after the feeding of the preceding medium P1 has finished. Therefore, the drive mechanism 100A of this embodiment is configured to move the leading medium P1 in the feeding direction F1 and the trailing medium P2 in the reverse feeding direction F2 by active retardation, which keeps the motor 210 running by turning off the clutch C of the gear 209 and switching the feeding roller 251 to a state where it can rotate freely.

[0045] More specifically, the drive mechanism 100A of this embodiment, as shown in Figures 2, 3, and 6, has a one-way clutch unit 205 on the rotation axis 215 of the feed roller 251, which consists of a locking unit 203 (details shown in Figure 10) and a star ratchet 204 (details shown in Figure 9). The drive mechanism 100A of this embodiment switches between a restricting state, where the feed roller 251 is restricted from rotating in the rotation direction R2b (shown in the rightmost figure of Figure 11, where the medium P moves in the reverse feed direction F2, opposite to the feed direction F1), and a permissible state, where the feed roller 251 is free to rotate and rotation in the rotation direction R2b is permitted, by turning the one-way clutch unit 205 on or off. Furthermore, in the restricted state, the feed roller 251 transports a predetermined amount of medium P and strikes the resist roller 311 and the gate member 311a provided on the resist roller 311 to perform skew correction. In this case, although the clutch C of gear 209 is in the off state, the rotating shaft 215 is in the restricted state because the one-way clutch section 205 is in the restricted state. This suppresses the return of the medium P, which moves in the reverse feeding direction F2 due to the springback of the torque limiter, and suppresses a decrease in the accuracy of skew correction. Thus, the drive mechanism 100A of this embodiment is configured to be switchable between a restricted state and a permissible state by turning the one-way clutch section 205 on or off. This makes it suitable for feeding the subsequent medium P2 after the feeding of the preceding medium P1 has finished when transporting multiple media P, and also suppresses recording disturbances and a decrease in the accuracy of skew correction in the medium P being recorded. Furthermore, in this embodiment, the drive mechanism 100A is in the restricted state by turning on the one-way clutch section 205, and by further turning off the clutch C of gear 209, it is possible to suppress the return of the medium during skew correction due to the springback of the torque limiter without stopping the drive of the motor 210.

[0046] Furthermore, as shown in Figures 2 to 6, the drive mechanism 100A of this embodiment has a pick roller 21, and a gear 206 provided on the rotation shaft 214 of the pick roller 21 engages with a gear 207 provided on the rotation shaft 215 of the feed roller 251 via another gear. Therefore, the pick roller 21 and the feed roller 251 can rotate in conjunction with each other. As shown in Figure 6, the rotation shaft 215 is provided with a gear 208 that engages with a gear 209 and a one-way clutch 205, and the driving force of the motor 210 is transmitted to the feed roller 251 and the pick roller 21 via the gears 209 and 208. However, as mentioned above, since the gear 209 has a clutch C, the driving force of the motor 210 can be prevented from being transmitted to the feed roller 251 and the pick roller 21 by turning off the clutch C of the gear 209.

[0047] Furthermore, as shown in Figures 2 to 6, the drive mechanism 100A of this embodiment has a solenoid 201. Also, as shown in Figures 2 and 3, a shaft portion 201a is attached to the solenoid 201, and the locking portion 203 of the one-way clutch portion 205 and the pick separation cam 202 are attached to the shaft portion 201a. When the solenoid 201 moves the shaft portion 201a along the -Y direction, the one-way clutch portion 205 is turned on as shown in Figure 2, and the pick separation cam 202 moves downward to a position where it does not contact the contact portion 218 as shown in Figure 4, causing the pick separation cam 202 to move downward to a position where it can contact the medium P. On the other hand, as the solenoid 201 moves the shaft portion 201a along the +Y direction, the one-way clutch portion 205 is turned off as shown in Figure 3, and as shown in Figure 5, the pick separation cam 202 comes into contact with the contact portion 218 and moves upward together with the contact portion 218, causing the pick separation cam 202 to move upward to a position where the pick roller 21 does not come into contact with the medium P.

[0048] In this embodiment, the drive mechanism 100A is configured such that both the feed roller 251 and the pick roller 21 are located above the feed path T0. This allows the feed roller 251 and the pick roller 21 to be placed in close proximity. This configuration makes it easy to switch between the pick release cam 202 and the one-way clutch 205, which are the separation mechanisms for the pick roller 21, using the same actuator, the solenoid 201, thus enabling miniaturization of the printer 1.

[0049] Here, the detailed configuration of the one-way clutch section 205 will be described with reference to Figures 7 to 10. As shown in Figures 7 and 8, the one-way clutch section 205 of this embodiment has a star ratchet 204 shown in Figure 9 and a locking section 203 shown in Figure 10. As shown in Figures 7 and 8, the star ratchet 204 and the locking section 203 face each other in the Y-axis direction, and teeth 204a protruding in the +Y direction are formed near the periphery of the opposing surface 204b of the star ratchet 204, and projections 203a that engage with the teeth 204a protruding in the -Y direction are formed near the periphery of the opposing surface 203b of the locking section 203.

[0050] Here, the locking portion 203 is configured to be movable along the Y-axis direction by the solenoid 201, but it is configured not to rotate with respect to the Y-axis direction as the axis of rotation because it is in contact with a frame (not shown) or the like. On the other hand, as shown in Figure 7, when the one-way clutch portion 205 is in the ON state, the star ratchet 204 can rotate freely in the rotational direction R6a relative to the locking portion 203 with respect to the Y-axis direction as the axis of rotation, but it is configured not to rotate freely in the rotational direction R6b relative to the locking portion 203. This is because the teeth 204a are configured to gradually decrease in the +Y direction in the rotational direction R6a, and the projection portion 203a is configured to gradually increase in the -Y direction. Therefore, when the star ratchet 204 rotates in the rotational direction R6a relative to the locking portion 203, the teeth 204a do not catch on the projection 203a, but when the star ratchet 204 rotates in the rotational direction R6b relative to the locking portion 203, the teeth 204a catch on the projection 203a. In other words, as shown in Figure 7, when the one-way clutch portion 205 is in the ON state, the star ratchet 204 can rotate freely in only one direction, R6a, relative to the locking portion 203. Note that, as shown in Figure 8, when the one-way clutch portion 205 is in the OFF state, the teeth 204a are not in contact with the projection 203a, so the star ratchet 204 can rotate freely in both the rotational direction R6a and the rotational direction R6b relative to the locking portion 203.

[0051] Next, with reference to Figures 11 and 12, an example of a feeding operation as a media transport method that can be performed by the printer 1 of this embodiment will be described. When the media transport method of this embodiment is started by turning on the motor 210 and turning on the active retard, the first step is the pick contact step S110, as shown in Figure 12.

[0052] In step S110, the pick roller contact process, the pick roller 21 is brought into contact with the medium P by turning on the solenoid 201. When the solenoid 201 is turned on, the one-way clutch unit 205 is also turned on, and the feed roller 251 is not allowed to rotate freely in the rotational direction R2b. The leftmost diagram in Figure 11 shows the state of the drive mechanism unit 100A at the start of the execution of the pick roller contact process in step S110. In this state, the clutch C of the gear 209 is off, the motor 210 is on, the one-way clutch unit 205 is on, the resist roller 311 is not rotating, and the rotating shaft 217 is rotating in the rotational direction R4. The pick roller 21 and the feed roller 251 are not rotating, and because the feed roller 251 is not allowed to rotate freely in the rotational direction R2b, the separation roller 252 that contacts the feed roller 251 is also not rotating.

[0053] Next, in the primary feeding process of step S120, the clutch C of gear 209 is turned on. As a result, as shown in the second figure from the left in Figure 11, the pick roller 21 rotates in the rotational direction R1 and the feeding roller 251 rotates in the rotational direction R2a. Although the rotating shaft 217 is rotating in the rotational direction R4, the separation roller 252 rotates in the rotational direction R3a in accordance with the rotation of the feeding roller 251. By executing the primary feeding process of step S120, the leading medium P1 of the medium P is fed.

[0054] Next, in the skew correction step S130, as shown in the third figure from the left in Figure 11, the leading edge of the leading medium P1 is brought into contact with the register roller 311 and the gate member 311a provided on the register roller 311 to perform skew correction. The printer 1 in this embodiment is equipped with a medium sensor (not shown), and after determining that the leading edge of the leading medium P1 has been in contact with the register roller 311 and the gate member 311a for a predetermined time using the detection result of the medium sensor, the clutch C of the gear 209 is turned off. As a result of the clutch C of the gear 209 being turned off, the pick roller 21 and the feed roller 251 are no longer rotating due to the driving force of the motor 210. Furthermore, because the one-way clutch unit 205 is turned on, it is in a restricted state, so the feeding roller 251 does not rotate freely in the rotational direction R3b, and the separation roller 252 that contacts the feeding roller 251 does not rotate in the rotational direction R3b, even though the rotation axis 217 is rotating in the rotational direction R4, and the return of the leading medium P1 due to the springback of the torque limiter is suppressed. In this way, by the leading edge of the leading medium P1 abutting against the resist roller 311 and the gate member 311a for a predetermined time, the leading edge of the leading medium P1 follows the resist roller 311 and the gate member 311a, and the skew is corrected.

[0055] Next, in the secondary feeding process of step S140, as shown in the fourth figure from the left in Figure 11, the register roller 311 is rotated in the rotational direction R5, and the clutch C of the gear 209 is turned on. By turning on the clutch C of the gear 209, the pick roller 21 rotates in the rotational direction R1, and the feeding roller 251 rotates in the rotational direction R2a. In addition, the separation roller 252 rotates in the rotational direction R3a in conjunction with the rotation of the feeding roller 251. By executing the secondary feeding process of step S140, the preceding medium P1 of the medium P is further fed.

[0056] Next, in the pick roller separation step S150, the pick roller 21 is separated from the medium P, as shown in the fifth figure from the left in Figure 11. Specifically, the pick roller 21 is separated from the medium P by turning off the solenoid 201. When the solenoid 201 is turned off, the one-way clutch unit 205 is also turned off, and the one-way clutch unit 205 enters an acceptable state. In the pick roller separation step S150, the resist roller 311 rotates in the rotational direction R5, further feeding of the leading medium P1 of the medium P, but at this time, feeding by the pick roller 21 ceases.

[0057] Next, in the separation roller release step S160, as shown in the sixth figure from the left in Figure 11, the clutch C of the gear 209 is kept on and the leading medium P1 is fed until the rear end of the leading medium P1 leaves the clamping position between the feed roller 251 and the separation roller 252. Before the start of the separation roller release step S160, recording has already begun near the leading edge of the leading medium P1, but during recording, feeding of the leading medium P1 by the feed roller 251 is stopped, and the feed roller pair 25 does not apply a force in the reverse feeding direction F2 to the leading medium P1 during recording. This is because if a force in the reverse feeding direction F2 is applied by the feed roller pair 25 during recording, the transport speed of the medium P may change suddenly, potentially causing band-like irregularities in the recorded image. Note that the fact that the rear end of the leading medium P1 has left the clamping position between the feed roller 251 and the separation roller 252 can be determined using the detection results of a medium sensor (not shown).

[0058] Finally, in the media return process of step S170, as shown in the rightmost diagram of Figure 11, the trailing medium P2, which was fed in the feeding direction F1 following the preceding medium P1 in the separation roller release process of step S160, is returned in the reverse feeding direction F2. Specifically, the clutch of gear 209 is turned off. With the clutch of gear 209 turned off, the driving force of motor 210 is no longer transmitted to the feeding roller 251. On the other hand, since motor 210 has been on throughout the period from step S110 to step S170, the rotation axis 217 of the separation roller 252 has been rotating continuously in the rotation direction R4. Since the driving force of motor 210 is no longer transmitted to the feeding roller 251, no rotational force is transmitted from the feeding roller 251 to the separation roller 252. Furthermore, the feeding roller 251 is in a state where it can freely rotate in the rotation direction R3b. On the other hand, since the rotation axis 217 of the separation roller 252 is constantly rotating in the rotation direction R4, the separation roller 252 rotates in the rotation direction R3b as the rotation axis 217 rotates, and consequently the feeding roller 251 rotates in the rotation direction R2b. As a result, the trailing medium P2, which is being held between the feeding roller 251 and the separation roller 252, returns to the reverse feeding direction F2. If the trailing medium P2 is to be fed again, each step of this flowchart from step S110 to step S170 is repeated.

[0059] As described above, the drive mechanism 100A of this embodiment includes a motor 210 as a drive unit that generates driving force, and a one-way clutch unit 205 provided in the transmission path that transmits driving force to the feed roller 251. Here, the one-way clutch unit 205 is switchable between an allowable state that permits the feed roller 251 to rotate in the rotational direction R2b that moves the medium P in the reverse feed direction F2, and a restrictive state that permits the feed roller 251 to rotate only in the rotational direction that moves the medium P in the feed direction F1. The drive mechanism 100A of this embodiment is configured such that the one-way clutch unit 205 is in the allowable state, and the separation roller 252 is rotated in the rotational direction R3b that moves the medium P in the reverse feed direction F2. Because of this configuration, the drive mechanism 100A in this embodiment can suppress the subsequent medium P2 from being forcefully thrown towards the mounting section after the preceding medium P1 has released from the clamping position between the feeding roller 251 and the separation roller 252, while appropriately returning the subsequent medium P2 following the preceding medium P1 to the first medium cassette 3.

[0060] In this embodiment, as described above, the rotation axis 217 of the separation roller 252 continues to rotate in the rotation direction R4 that moves the medium P in the reverse feeding direction F2 when the motor 210 is turned on, but the system is not limited to this configuration. Other configurations may include driving the motor 210 to rotate the separation roller 252 when returning the subsequent medium P2 following the preceding medium P1 to the first medium cassette 3 side, or connecting the separation roller 252 to the motor 210 that rotates the separation roller 252 when returning the subsequent medium P2 following the preceding medium P1 to the first medium cassette 3 side.

[0061] Furthermore, using the printer 1 of this embodiment, a media transport method can be implemented that includes, as a media double-feed suppression operation, a feeding step corresponding to steps S120 and S140, in which the media P is gripped between the feeding roller 251 and the separation roller 252 and fed in the feeding direction F1, and a subsequent media return step corresponding to step S170, in which the one-way clutch section 205 is set to an allowable state and the separation roller 252 is rotated in the rotation direction R3b so that the media P moves in the reverse feeding direction F2, thereby returning the subsequent media P2, which follows the preceding media P1 that is transported in the feeding step, back to the reverse feeding direction F2. By implementing such a media transport method, it is possible to suppress the subsequent media P2 from being forcefully thrown towards the first media cassette 3 after the preceding media P1 has released from the gripping position between the feeding roller 251 and the separation roller 252, while appropriately returning the subsequent media P2 following the preceding media P1 to the first media cassette 3.

[0062] Furthermore, as described above, the printer 1 of this embodiment is provided with a pick roller 21 as a transport roller that is located upstream of the feed roller 251 in the feed direction F1 and transports the medium P from the first medium cassette 3 toward the feed roller 251. The drive mechanism 100A of this embodiment has a solenoid 201 as a switching unit that switches the pick roller 21 between a contact state in contact with the medium P and a separated state away from the medium P, and is capable of transmitting driving force to the pick roller 21, and the one-way clutch unit 205 can be switched between a restrictive state and a permissive state by the switching operation of the solenoid 201 between the contact state and the separated state. In other words, the printer 1 of this embodiment can switch the state of the one-way clutch unit 205 between a restrictive state and a permissive state using the power that switches the state of the pick roller 21. For this reason, the printer 1 of this embodiment can simplify the device configuration.

[0063] Furthermore, as described above, the drive mechanism 100A of this embodiment restricts the one-way clutch 205 when the solenoid 201 is in contact with the pick roller 21, corresponding to Figures 2 and 4, and allows the one-way clutch 205 when the solenoid 201 is separated from the pick roller 21, corresponding to Figures 3 and 5. Therefore, as shown in the rightmost figure of Figure 11, the printer 1 of this embodiment can suppress jams and skews caused by the leading edge of the subsequent medium P2 in the reverse feeding direction F2 getting caught on the pick roller 21 when returning the subsequent medium P2 following the preceding medium P1 to the first medium cassette 3 side by separating the pick roller 21.

[0064] Furthermore, as described above, the one-way clutch portion 205 of the drive mechanism portion 100A in this embodiment has a star ratchet 204 with teeth that allow rotation in one direction but prevent rotation in the other direction. By configuring the one-way clutch portion 205 in this way, the drive mechanism portion 100 can be miniaturized, and the printer 1 can be miniaturized. In this embodiment, the star ratchet 204 has teeth 204a that protrude in a direction along the rotation axis 215, and by adopting this configuration, both the star ratchet 204 and the locking portion 203 can be particularly miniaturized in the direction that intersects the rotation axis 215.

[0065] Furthermore, as described above, the printer 1 of this embodiment is equipped with a pair of transport rollers 31 that are located downstream of the feed rollers 251 in the feed direction F1 and act as a skew correction unit that contacts the medium P and corrects the skew of the medium P.The drive mechanism 100A of this embodiment, when the medium P fed by the feed rollers 251 comes into contact with the resist rollers 311 and gate member 311a of the transport roller pair 31, restricts the one-way clutch unit 205 and cuts off the transmission of driving force from the motor 210 to the feed rollers 251, as shown in the third figure from the left in Figure 11.With this configuration, it is possible to suppress damage to the preceding medium P1 or jamming that can occur due to the force being continuously applied to the preceding medium P1 in the feed direction F1 after the preceding medium P1 has come into contact with the skew correction unit.

[0066] Furthermore, as described above, the printer 1 of this embodiment has a pair of transport rollers 31 that transport the medium P as a skew correction unit, and the solenoid 201 switches the pick roller 21 from a contact state to a separated state when the medium P, whose skew has been corrected by the transport roller pair 31, is transported by the transport roller pair 31, as shown in the fifth figure from the left in Figure 11. In other words, in the printer 1 of this embodiment, when the medium P, whose skew has been corrected, is transported by the transport roller pair 31, the medium P is not transported by the pick roller 21. In this way, the transport load can be reduced by reducing the number of transport units that are involved in transporting the medium P. In this embodiment, the pick roller 21 is switched from a contact state to a separated state in synchronization with the timing when the medium P is transported by the transport roller pair 31, but these timings may be different.

[0067] Furthermore, as described above, the printer 1 of this embodiment is equipped with a line head 51 as a recording unit that is located downstream of the transport roller pair 31 in the feeding direction F1 and performs recording on the medium P.The drive mechanism 100A of this embodiment, as shown in the sixth figure from the left in Figure 11, continues to transmit driving force from the motor 210 to the transport roller 251 until the rear end of the medium P being recorded by the line head 51 in the feeding direction F1 passes the clamping position between the transport roller 251 and the separation roller 252.If the transmission of driving force to the transport roller 251 stops before the medium P passes the clamping position between the transport roller 251 and the separation roller 252 while recording is in progress by the recording unit, the transport distance per unit time may change abruptly, which may lead to a decrease in recording quality. However, in the printer 1 of this embodiment, the drive mechanism 100A continues to transmit driving force from the motor 210 to the feed roller 251 until the rear end of the medium P being recorded by the line head 51 in the feeding direction F1 passes the clamping position between the feed roller 251 and the separation roller 252. Therefore, the printer 1 of this embodiment can suppress abrupt changes in the transport distance per unit time while recording is in progress by the line head 51, and can suppress a decrease in recording quality.

[0068] [Example 2] The drive mechanism 100 of the printer 1 of Embodiment 2 will be described below with reference to Figure 13. Figure 13 is the same as Figure 6 in the printer 1 of Embodiment 1. The printer 1 of this embodiment is the same as the printer 1 of Embodiment 1 except for the configuration described below. In detail, only the configuration of the drive mechanism 100 differs from the printer 1 of Embodiment 1, and in further detail, only the arrangement of the gear having the clutch C with respect to the drive mechanism 100A of Embodiment 1 differs from the printer 1 of Embodiment 1. For this reason, the printer 1 of this embodiment has the same characteristics as the printer 1 of Embodiment 1 except for the parts described below. Therefore, in Figure 13, components common to Embodiment 1 are indicated by the same reference numerals, and detailed explanations are omitted.

[0069] As shown in Figure 6, in the drive mechanism 100A of Embodiment 1, the clutch C was attached only to the gear 209 that engages with the gear 208 attached to the rotating shaft 215 of the feed roller 251. On the other hand, as shown in Figure 13, in the drive mechanism 100B of this embodiment, the clutch C is also attached to the gear 219 that receives the driving force from the motor 210. Therefore, the drive mechanism 100B of this embodiment can drive the motor 210 while preventing the rotating shaft 217 of the separation roller 252 from receiving the driving force from the motor 210. With this configuration, for example, it is possible to drive the motor 210 to drive some of the multiple rollers provided in the printer 1, while preventing the separation roller 252 from being driven in addition to the pick roller 21 and the feed roller 251.

[0070] [Example 3] The drive mechanism 100 of the printer 1 of Embodiment 3 will be described below with reference to Figure 14. Figure 14 is the same as Figure 6 in the printer 1 of Embodiment 1. The printer 1 of this embodiment is the same as the printer 1 of Embodiment 1 except for the configuration described below. In detail, only the configuration of the drive mechanism 100 differs from the printer 1 of Embodiment 1, and in further detail, only the arrangement of the gear having the clutch C with respect to the drive mechanism 100A of Embodiment 1 differs from the printer 1 of Embodiment 1. For this reason, the printer 1 of this embodiment has the same characteristics as the printer 1 of Embodiment 1 except for the parts described below. Therefore, in Figure 14, components common to Embodiment 1 are indicated by the same reference numerals, and detailed explanations are omitted.

[0071] As shown in Figure 6, in the drive mechanism 100A of Embodiment 1, the clutch C was attached only to the gear 209 that engages with the gear 208 attached to the rotating shaft 215 of the feed roller 251. On the other hand, as shown in Figure 13, in the drive mechanism 100C of this embodiment, the clutch C is also attached to the gear 220 that engages with the gear 213 attached to the rotating shaft 217 of the separation roller 252. Therefore, the drive mechanism 100B of this embodiment can drive the motor 210 while preventing the rotating shaft 217 of the separation roller 252 from receiving the driving force from the motor 210. With this configuration, similar to the drive mechanism 100B of Embodiment 2, for example, the motor 210 can be driven to drive some of the multiple rollers provided in the printer 1, while preventing the separation roller 252 from being driven in addition to the pick roller 21 and the feed roller 251.

[0072] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention as described in the claims, and it goes without saying that these modifications are also included within the scope of the present invention. [Explanation of Symbols]

[0073] 1... Inkjet printer (media transport device), 2... Main unit, 3... First media cassette (mounting section), 4... Second media cassette, 5... Third media cassette, 6... Expansion unit, 8... Discharge tray, 11... Waste liquid storage section, 13... Transport belt, 14... Pulley, 15... Pulley, 16... Housing section, 17... Door section, 19... Supply roller, 20... Separation roller, 21... Pick roller (transport roller), 22... Pick roller, 23... Pick roller, 25... Feeding roller pair, 26... Supply 27...Feeding roller pair, 28...Conveyor roller pair, 29...Conveyor roller pair, 31...Conveyor roller pair (skew correction unit), 32...Conveyor roller pair, 33...Conveyor roller pair, 34...Conveyor roller pair, 35...Conveyor roller pair, 36...Conveyor roller pair, 37...Conveyor roller pair, 39...Reversing roller, 40...Driven roller, 41...Flap, 50...Head unit, 51...Line head (recording unit), 61...Ink storage unit, 62...Ink storage unit, 63...Ink storage unit Part, 64...Ink storage part, 100...Drive mechanism part, 100A...Drive mechanism part, 100B...Drive mechanism part, 100C...Drive mechanism part, 201...Solenoid (switching part), 201a...Shaft part, 202...Pick separation cam, 203...Locking part, 203a...Protrusion part, 203b...Opposite surface, 204...Star ratchet, 204a...Teeth, 204b...Opposite surface, 205...One-way clutch part, 206...Gear, 207...Gear, 208...Gear, 209...Gear, 210...Motor (drive part), 211...Gear 212...gear, 213...gear, 214...rotating shaft, 215...rotating shaft, 216...rotating shaft, 217...rotating shaft, 218...contact part, 219...gear, 220...gear, 251...feeding roller, 252...separation roller, 311...resist roller, 311a...gate member, 312...driven roller, C...clutch, K1...branching position, P...medium, P1...leading medium, P2...following medium, S1...merging point, T0...feeding path, T1...conveying path during recording, T2...switchback path, T3...reversal path

Claims

1. A mounting section on which the media is placed, A feeding roller that feeds the medium from the mounting section in the feeding direction, The aforementioned medium is rotatable in a rotational direction that moves toward the aforementioned placement section and in a reverse feeding direction opposite to the feeding direction, and a separation roller that, together with the feeding roller, grips the medium and separates multiple stacked sheets of the medium, A drive mechanism that drives the feeding roller and the separating roller, Equipped with, The drive mechanism comprises a drive unit that generates driving force and a one-way clutch unit provided in a transmission path that transmits the driving force to the feed roller. The one-way clutch section is switchable between a permissive state that allows the feed roller to rotate in the rotational direction that moves the medium in the reverse feeding direction, and a restrictive state that allows the feed roller to rotate only in the rotational direction that moves the medium in the feeding direction. The drive mechanism is configured such that the one-way clutch is in the allowable state, and the separating roller is rotated in the rotational direction in which the medium moves in the reverse feeding direction. A skew correction unit is provided downstream of the feeding roller in the feeding direction, and contacts the medium to correct the skew of the medium. When the medium supplied by the supply roller comes into contact with the skew correction unit, the drive mechanism unit sets the one-way clutch unit to the restricting state and cuts off the transmission of the driving force to the supply roller. A conveying roller is provided upstream of the feeding roller in the aforementioned feeding direction, and conveys the medium from the aforementioned mounting section toward the feeding roller, The drive mechanism has a switching unit that switches the transport roller between a contact state in which it is in contact with the medium and a separated state in which it is separated from the medium, and is capable of transmitting the driving force to the transport roller. The skew correction unit has a pair of transport rollers for transporting the medium, The medium conveying device is characterized in that the switching unit switches the conveying rollers from the contact state to the separated state when the medium, whose skew has been corrected by the skew correction unit, is conveyed by the conveying roller pair.

2. In the media transport device according to claim 1, A recording unit is provided downstream of the skew correction unit in the feeding direction and performs recording on the medium, The media conveying device is characterized in that the drive mechanism continues to transmit the driving force to the feed roller until the rear end of the medium being recorded by the recording unit in the feeding direction leaves the clamping position between the feed roller and the separation roller.

3. In the media transport device according to claim 1 or 2, A media transport device characterized in that the one-way clutch section is switched between the restrictive state and the allowable state by a switching operation of the switching section between the contact state and the separated state.

4. In the media transport device according to claim 3, The drive mechanism is characterized in that when the switching unit brings the transport roller into contact with the transport roller, the one-way clutch unit is set to the restricting state, and when the switching unit brings the transport roller into the separated state, the one-way clutch unit is set to the allowing state.

5. In the media transport device according to claim 1 or 2, The media transport device is characterized in that the one-way clutch section has a star ratchet.

6. A mounting section on which the media is placed, A feeding roller that feeds the medium from the mounting section in the feeding direction, The aforementioned medium is rotatable in a rotational direction that moves toward the aforementioned placement section and in a reverse feeding direction opposite to the feeding direction, and a separation roller that, together with the feeding roller, grips the medium and separates multiple stacked sheets of the medium, A drive mechanism that drives the feeding roller and the separating roller, A drive unit that generates driving force, A one-way clutch unit is provided in the transmission path that transmits the driving force to the feeding roller, and is switchable between an allowable state that permits the feeding roller to rotate in the rotational direction that moves the medium in the reverse feeding direction, and a restrictive state that permits the feeding roller to rotate only in the rotational direction that moves the medium in the feeding direction. A skew correction unit is provided downstream of the feed roller in the aforementioned feeding direction, and contacts the medium to correct the skew of the medium, A conveying roller is provided upstream of the feeding roller in the aforementioned feeding direction and conveys the medium from the aforementioned mounting section toward the feeding roller, Equipped with, When the medium supplied by the supply roller comes into contact with the skew correction unit, the drive mechanism unit sets the one-way clutch unit to the restricting state and cuts off the transmission of the driving force to the supply roller. The drive mechanism has a switching unit that switches the transport roller between a contact state in which it is in contact with the medium and a separated state in which it is separated from the medium, and is capable of transmitting the driving force to the transport roller. The skew correction unit has a pair of transport rollers for transporting the medium, The switching unit is configured to switch the transport rollers from the contact state to the separated state when the medium, whose skew has been corrected by the skew correction unit, is being transported by the transport roller pair. A method for transporting media in a media transport device, A feeding step in which the medium is sandwiched between the feeding roller and the separation roller and fed in the feeding direction, A subsequent medium return step is performed by setting the one-way clutch to the permissible state and rotating the separation roller in the rotational direction in which the medium moves in the reverse feeding direction, thereby returning the subsequent medium from the medium that follows the preceding medium conveyed in the feeding step back in the reverse feeding direction. A media transport method characterized by performing the following:

Images