JP2009062190A - Automatic document feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic document feeder and an image forming device having the document feeder, capable of reducing the size and cost in the device by smoothly and surely carrying a document, even if a carrying passage up to switching back again after switching back the document, is set to the length or less in the carrying direction of the document. <P>SOLUTION: In this automatic document feeder 71, a torque limiter 19 limits torque applied to a driving shaft (a shaft of a reversal roller) 70 to torque for co-rotating the reversal roller 11a by frictional force with the document S when the switched back document S is carried by a carrier roller 5b. A one-way clutch 67 interlocks with a driven member 69 only when the driving shaft 79 reversely rotates, and stops reverse rotation of the driving shaft 79 by stopping rotation of the driven member 69 by abutting on the driven member 69 when a switching member 10 moves to a guide position A to a third carrying passage (a switchback carrying part) 33. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an automatic document feeder having a function for reading both sides of a document and an image forming apparatus provided with the automatic document feeder.

  In the automatic document feeder having a double-sided document reading function described in Patent Document 1, when a plurality of pages of a document are scanned on both sides, if the document is ejected as it is after the document is scanned on both sides, the page order of the ejected documents In order to adjust the page order, the document is switched back again by reverse rotation of the reverse roller and then discharged.

Japanese Patent No. 3612218

  However, in the case of a document S that is long in the transport direction (for example, A3), as shown in FIG. 5, the document S is switched back and the document trailing edge 101 does not pass through the nip between the pair of reverse rollers 103a and 103b. When the document front end 105 enters the nip of the pair of reversing rollers 103a and 103b, the reversing roller 103a rotates in the reverse direction (in the direction of the arrow in FIG. 5), so that the document front end 105 can enter the nip of the pair of reversing rollers 103a and 103b. It becomes jam. Therefore, in order to allow the leading edge 105 of the document to enter the nip of the pair of reversing rollers 103a and 103b with the trailing end 101 of the document passing through the nip of the pair of reversing rollers 103a and 103b and rotating the reversing roller 103a forward. Therefore, the transport path of the document S needs to be longer than the length of the document S in the transport direction. In particular, it is necessary to provide a transport path that is longer than the transport direction length of the maximum size document, which increases the size of the apparatus and increases the cost.

  Therefore, according to the present invention, even if the transport path from when the document is switched back to when it is switched back is not longer than the length in the document transport direction, the document can be transported smoothly and reliably, thereby reducing the size of the apparatus. An object of the present invention is to provide an automatic document feeder capable of reducing costs and an image forming apparatus provided with the automatic document feeder.

  In order to solve the above-mentioned problem, the invention described in claim 1 includes a transport roller for transporting a document to the image reading unit and a reversing roller that rotates in the forward and reverse directions. An automatic document feeder comprising: a switchback conveyance unit that carries in by rotation and carries out by reverse rotation; and a switching member that switches a conveyance destination of a document after image reading to a switchback conveyance unit or a discharge unit. A driven member that follows the rotation of the shaft, a one-way clutch that connects the shaft of the reverse roller and the driven member, and a torque limiter that restricts drive transmission from the drive source to the shaft of the reverse roller. The torque applied to the shaft of the reversing roller when the switched back document is conveyed by the conveying roller is limited to the torque that the reversing roller rotates with the frictional force with the document. H is interlocked with the driven member only when the shaft of the reversing roller is rotating in the reverse direction, and when the switching member moves to the guide position to the switchback conveyance path, the rotation of the driven member is stopped by contacting the driven member. By doing so, the reverse rotation of the shaft of the reversing roller is stopped.

  In the invention described in claim 2, in the invention described in claim 1, the switching member is pivotally supported rotatably at the guide position to the switchback transport section or the guide position to the discharge section. A contact portion that contacts the driven member at one end is provided, and the contact portion contacts the driven member when the switching member rotates from the guide position to the discharge portion to the guide position to the switchback conveying portion. .

  According to a third aspect of the present invention, in the second aspect of the present invention, the outer periphery of the driven member is formed with irregularities, the abutting portion is provided with an elastic deformation member, and the elastic deformation member is a member of the driven member. It is characterized by contacting with the outer periphery.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the automatic document feeder according to any one of the first to third aspects.

  According to the present invention, when the document is switched back again, when the leading end of the document enters the nip of the reversing roller before the trailing end of the document switched back by the reverse rotation of the reversing roller comes out of the nip of the reversing roller. The torque in the reverse rotation direction transmitted to the shaft of the reversing roller is limited to the torque that the reversing roller rotates around the document by the torque limiter, and the follower rotates in reverse with the shaft of the reversing roller in conjunction with the one-way clutch. Since the member is stopped and the reverse rotation of the shaft of the reverse roller is stopped, the leading edge of the original can smoothly and reliably enter the nip of the reverse roller. Therefore, even if the transport path from when the document is switched back to when it is switched back is less than the length in the document transport direction, the document can be transported smoothly and reliably, thereby reducing the size and cost of the apparatus. Can be planned.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a side view in which the vicinity of the switching member of the automatic document feeder according to the present embodiment is extracted, and shows a state in which the switching member is in the guide position to the third conveyance path. FIG. 2 is a side view in which the vicinity of the switching member of the automatic document feeder according to the present embodiment is extracted, and shows a state in which the switching member is in the guide position to the fourth conveyance path. FIG. 3 is a longitudinal sectional view showing a schematic configuration of the automatic document feeder according to the present embodiment, in which the leading end of the document enters the nip of the reversing roller while the trailing end of the document is nipped by the nip of the reversing roller pair. Is shown. FIG. 4 is a perspective view showing the periphery of the switching member of the automatic document feeder according to the present embodiment.

  As shown in FIG. 3, the automatic document feeder 71 according to the present embodiment is provided on the upper side of an image forming unit 75 of an image forming apparatus 73 such as a copying machine, a facsimile, or a complex machine thereof. The image forming unit 75 includes an image reading unit 7 that reads an image of the document S through contact glass, an image carrier on which an electrostatic latent image corresponding to the image read by the image reading unit 7 is formed, A developing unit that supplies toner to the electrostatic latent image formed on the holder and develops the electrostatic latent image as a toner image, a transfer unit that transfers the toner image to a sheet, and a toner image that is transferred to the sheet are fixed. The image forming apparatus includes a fixing unit and forms an image corresponding to an original image on a sheet. However, in the present embodiment, illustration and detailed description thereof are omitted.

  The automatic document feeder 71 includes a document stacking table 1 on which a document stack 20 in which a plurality of documents S are stacked to form a bundle is inserted and set, and a call roller 2 that sends out the document stack 20 set on the document stacking table 1. A separation feeding unit 40 that separates and feeds the document bundle 20 of the document stacking table 1 one by one; and a document S fed from the separation feeding unit 40 is conveyed toward the image reading unit 7. A first conveyance path 31, a second conveyance path 32 that conveys the document S that has passed through the image reading unit 7 toward the downstream side, a discharge section 12 that stacks the document S conveyed by the second conveyance path 32, A third conveyance path (switchback conveyance) that has a reverse rotation roller that rotates in reverse and carries the document S conveyed by the second conveyance path 32 by forward rotation (C1 direction) of the reverse roller and unloads by reverse rotation (C2 direction). Part) 33 and the second transport path 32 The conveying destination of the document S and a switching member 10 for switching to the discharge unit 12 or the third transport path 33. As the document conveying means, the first conveying path 31 includes conveying roller pairs 5a and 5b and conveying roller pairs 6a and 6b, and the second conveying path 32 includes conveying roller pairs 8a and 8b and discharge roller pairs 9a and 9b. The third conveying path 33 is provided with a pair of reversing rollers 11a and 11b, and the fourth conveying path 34 is provided with a pair of conveying rollers 9b and 9c. An abutting sensor 21 that detects the document S is provided in the vicinity of the transport roller 5b, and a registration sensor 22 that detects the document S on the upstream side of the transport roller pair 6a, 6b and the downstream side of the transport roller pair 5a, 5b. A discharge sensor 23 for detecting the document S is provided on the upstream side of the discharge roller pair 9a, 9b and on the downstream side of the conveyance roller pair 8a, 8b.

  As shown in FIG. 1, the reverse roller 11a is fixed to a drive shaft (reverse roller shaft) 79, and the drive shaft 79 is driven by a motor 81 via a torque limiter 19 (see FIG. 4). It has become. The torque limiter 19 is set so as to limit the torque that the reversing roller 11a rotates with the frictional force with the document S. The torque limiter is a device that limits torque transmission when a predetermined torque is applied.

  The drive shaft 79 is provided with a driven member 69 that follows the rotation of the drive shaft 79 and a one-way clutch 67 that connects the drive shaft 79 and the driven member 69. The one-way clutch 67 is fixed to the drive shaft 79.

  In the one-way clutch 67, as shown in the partially enlarged sectional view of FIG. 1, a ball 59 is attached to one end of the coil spring 57, and the other end of the coil spring 57 is fixed to the end of the notch 61 of the one-way clutch 67. The ball 59 is fitted in the notch 61 while being urged in the C1 direction. The ball 59 is in contact with the driven member 69, and a plurality of irregularities 83 are formed on the outer periphery of the driven member 69.

  When the drive shaft 79 and the one-way clutch 67 rotate in the C1 direction, the frictional force between the ball 59 and the one-way clutch 67 decreases, and the one-way clutch 67 and the driven member 69 are not interlocked. On the other hand, when the drive shaft 79 and the one-way clutch 67 rotate in the C2 direction, the frictional force between the ball 59 and the one-way clutch 67 increases, and the one-way clutch 67 and the driven member 69 are interlocked.

  That is, the drive shaft 79 and the reversing roller 11a do not interlock with the driven member 69 when rotated forward (C1 direction), but interlock with the driven member 69 when rotated reversely (C2 direction). Therefore, when the rotation of the driven member 69 stops, the reverse rotation (C1 direction) of the reversing roller 11a is allowed, but the reverse rotation (C2 direction) is stopped.

  The switching member 10 includes a document guide portion 53 and a contact portion 55 that contacts the driven member 69. The switching member 10 is pivotally supported on a shaft 13 parallel to the drive shaft 79. The shaft 13 is provided on one end side of the document guide portion 53.

  The switching member 10 is urged by the elastic force of the spring from the A position to the B position, and is turned from the B position to the A position by energizing the solenoid to cut off energization to the solenoid. It rotates from the position to the B position. Thereby, the switching member 10 is rotatable between the guide position (A position) to the third transport path 33 and the guide position (B position) to the discharge unit 12. The B position is also a guide position from the third conveyance path 33 to the fourth conveyance path 34. The switching member 10 is a stopper provided at a location that does not affect the document conveyance, and sets an upper limit (B position) and a lower limit (A position).

  The contact portion 55 extends to the lower side of the drive shaft 79 continuously to one end of the document guide portion 53 and rotates in the same direction as the document guide portion 53. A rubber (elastic deformation member) 52 is fixed to the contact portion 55 so as to face the outer periphery of the driven member 69. When the switching member 10 is rotated from the B position to the A position, the rubber 52 is moved to the one-way clutch 51. The follower member 69 abuts on the outer periphery.

  The operation of the automatic document feeder according to this embodiment will be described below. In response to a feed start signal from the main body of the image forming apparatus, the calling roller 2 descends and comes into pressure contact with the document S. As the calling roller 2 rotates, the document S is separated from the uppermost one by the feeding belt 3 and the separation roller 4. It is sent to the feeding unit 40, and only the uppermost sheet is separated and sent out. The separated document S is abutted against the temporarily stopped conveyance roller pairs 5a and 5b, corrects the inclination, and then restarts the first conveyance path 31 by the conveyance roller pairs 5a and 5b and the conveyance roller pairs 6a and 6b. And is conveyed toward the image reading unit 7.

  In the case of reading only the first image surface (single-sided mode), the document S is read by the image reading unit 7 and then the second conveyance having the conveyance roller pairs 8a and 8b and the discharge roller pairs 9a and 9b. It is discharged to the discharge unit 12 through the path 32. At this time, the switching member 10 is held at the position B in FIG. 2 and guides the document S to the discharge unit 12.

  In the case of double-sided reading (double-sided mode) of the document S, the document S sent from the separation feeding unit 40 passes through the first conveyance path 31 and the image reading unit 7 reads an image so as to read the first image surface.

  The document S after the image reading passes through the second conveyance path 32 and is conveyed to the third conveyance path 33 by the normal rotation (C1 direction) of the reverse roller 11a in order to perform switchback. At this time, the switching member 10 rotates from the B position to the A position at the timing when the leading edge of the document is detected by the discharge sensor 23, and guides the document S conveyed from the second conveyance path to the third conveyance path.

  The document S that has been transported to the third transport path 33 faces the downstream side of the switching member 10, its rear end passes through the discharge roller pair 9 a, 9 b, and the reversing roller pair 11 a, 11 b can sandwich the document S. After advancing the distance, it is switched back by the reverse rotation (C2 direction) of the reverse roller 11a and conveyed to the fourth conveyance path 34. At this time, the switching member 10 is rotated from the A position to the B position after a predetermined time has elapsed after the leading edge of the document is detected by the discharge sensor 23 and guides the document S to the fourth conveyance path.

  The inclination of the document S is corrected by abutting the leading edge 63 of the document S, which has advanced the fourth transport by the transport roller pair 9b, 9c, against the transport roller pair 5a, 5b that is temporarily stopped.

  After the butting correction, the restarted transport roller pair 5a and 5b starts to rotate in the direction in which the document S is transported to the first transport path. At this time, the reverse rotation (C2 direction) driving force is transmitted to the reverse roller 11a having the same drive source (motor 81) as the transport roller 5b, but the document S is transferred to the nip between the reverse roller pair 11a and 11b. Since it is sandwiched, the torque limiter 19 connected between the reversing roller 15 and the drive source is operated, and the reversing roller 11 a moves the document S to the first transport path 31 by the frictional force with the document S. Take around.

  The document S passing through the fourth conveyance path 34 and passing through the first conveyance path 31 is read by the image reading unit 7 on the second image surface.

  When the second image surface is read and then discharged as it is, it is sent to the discharge unit 12 via the second conveyance path 32. When the original S is reversed again and the page order is adjusted so that the first image surface faces downward and is stacked on the discharge unit 12, the switching member 10 is rotated from the B position to the A position, and the original S is moved to the first position. After being transported to the third transport path 33 and switched back, it is transported to the third transport path 33 again via the fourth transport path 34, the first transport path 31, and the second transport path 32.

  At this time, the length of the document S in the conveyance direction is determined by the conveyance path length (the length from the reverse roller 11a to the return to the reverse roller 11a via the fourth conveyance path 34, the first conveyance path 31, and the second conveyance path 32). In the case of a long document S, as shown in FIGS. 1 and 3, the document leading edge 63 enters the nip of the pair of reversing rollers 11a and 11b while the document trailing edge 65 side is sandwiched between the pair of reversing rollers 11a and 11b. .

  The reversing roller 15 rotates in the reverse direction (C2 direction) until the discharge sensor 23 detects the leading edge 63 of the document. When the discharge sensor 23 detects the document leading edge 63 and the switching member 10 rotates from the B position to the A position, the rubber 52 fixed to the contact portion 55 of the switching member 10 contacts the outer periphery of the driven member 69. . The abutted rubber 52 bites into the irregularities 83 formed on the outer periphery of the driven member 69, and the driven member 69 stops. Thereby, the reverse rotation (C2 direction) of the one-way clutch 67 interlocked with the driven member 69 is stopped, and the reverse rotation (C2 direction) of the drive shaft 79 and the reverse roller 11a is also stopped. On the other hand, even if the driven member 69 stops, the one-way clutch 67 does not interlock with the driven member 69 when rotating forward (in the C1 direction), so that the forward rotation (C1 direction) of the drive shaft 79 and the reverse roller 11a is not hindered. Further, the torque in the reverse rotation direction of the reversing roller 11 a is limited by the torque limiter 19 to the torque that the reversing roller 11 a is rotated by the frictional force with the document S.

  In this state, when the document leading edge 63 enters the nip between the pair of reversing rollers 11 a and 11 b, the reversing roller 11 a follows the document S, and the document S is smoothly and reliably transported to the third transport path 33.

  On the other hand, when the length of the document S in the transport direction is shorter than the length of the transport path, the reverse rotation (C2 direction) of the reversing roller 11a is stopped when the front end 63 of the document enters the nip between the pair of reversing rollers 11a and 11b. Since the forward rotation (C1 direction) is permitted and the torque in the reverse rotation direction transmitted to the reversing roller 11a is limited by the torque limiter 19, the document S is smoothly and reliably conveyed to the third conveyance path 33. The

  The document S transported to the third transport path 33 is temporarily held downstream of the switching member 10 with the second image surface facing downward. Thereafter, the switching member 10 is rotated from the A position to the B position, and the document S once held downstream of the switching claw 13 is switched back to the fourth conveying path 34, the first conveying path 31, and the second. The paper passes through the conveyance path 32 and is discharged to the discharge unit 12 with the first image surface facing downward.

  Below, the effect in this Embodiment is demonstrated. When the document S is switched back again, the document leading edge 63 is turned to the reverse roller before the trailing edge 65 of the document S switched back by the reverse rotation (C2 direction) of the reverse roller 11a comes out of the nip of the reverse roller pair 11a, 11b. When entering the nip of the pair 11a, 11b, the torque in the reverse rotation direction transmitted to the reverse roller 11a is limited by the torque limiter 19 to the torque that the reverse roller 11a rotates around the document S, and the one-way clutch 67, the driven member that rotates in the reverse direction (C2 direction) together with the drive shaft (reverse roller shaft) 79 is stopped and the reverse rotation (C2 direction) of the drive shaft 79 is stopped. Can smoothly and reliably enter the nip. Accordingly, even if the transport path from the time when the document S is switched back to the time when the document S is switched back is less than the length of the document S in the transport direction, the document can be transported smoothly and reliably, thereby reducing the size and cost of the apparatus. You can go down.

  The one-way clutch 67 and the drive shaft are stopped by bringing the contact portion 55 of the switching member 10 into contact with the outer periphery of the driven member 69 provided on the drive shaft (reverse roller shaft) 79 of the reverse roller 11a and stopping the driven member 69. Since the reverse rotation (C2 direction) 79 is stopped, the reverse rotation (C2 direction) of the reverse roller 11a can be stopped with a simple configuration.

  By bringing the rubber (elastic deformation member) 52 into contact with the outer periphery of the driven member 69, the outer periphery of the driven member 69 can be bitten, so that the driven member 32 can be stopped reliably.

  The automatic document feeder 71 according to the present embodiment can be mounted on an image forming apparatus 73 such as a copying machine or a facsimile.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the paper.

  In the above-described embodiment, the rubber 52 is used as the elastic deformation member fixed to the contact portion 55. However, instead of this, foamed polyurethane or the like may be used.

FIG. 6 is a side view of the vicinity of a switching member of the automatic document feeder according to the present embodiment, showing a state in which the switching member is in a guide position to a third conveyance path. FIG. 6 is a side view of the vicinity of a switching member of the automatic document feeder according to the present embodiment, showing a state in which the switching member is in a guide position to a fourth conveyance path. 1 is a longitudinal sectional view showing a schematic configuration of an automatic document feeder according to the present embodiment, and shows a state in which the leading end of the document enters the nip of the reverse roller while the rear end side of the document is held by the nip of the reverse roller pair. ing. FIG. 3 is a perspective view showing a periphery of a switching member of the automatic document feeder according to the present embodiment. FIG. 6 is a longitudinal sectional view showing a schematic configuration of an automatic document feeder according to a conventional example, and shows a state in which the leading end of the document enters the nip of the reversing roller while the trailing end side of the document is nipped by the nip of the reversing roller pair. .

Explanation of symbols

5b Conveying roller 7 Image reading unit 10 Switching member 11a Reverse roller 12 Discharge unit 19 Torque limiter 33 Third conveying path (switchback conveying unit)
52 Rubber (elastic deformation member)
55 Abutting portion 67 One-way clutch 69 Follower member 71 Automatic document feeder 73 Image forming device 79 Drive shaft (reverse roller shaft)
81 Motor (drive source)
83 Concavity and convexity S Document A Guide position to third transport path (switchback transport section) B Guide position to discharge section C1 Forward rotation C2 Reverse rotation

Claims (4)

  A transport roller that transports the document to the image reading unit, a reversing roller that rotates forward and backward, a switchback transport unit that transports the document after image scanning by forward rotation of the reversing roller and unloads by reverse rotation, and after image scanning An automatic document feeder having a switching member that switches a document transport destination to a switchback transport unit or a discharge unit, a driven member that follows the rotation of the shaft of the reverse roller, the shaft of the reverse roller, and the driven member And a torque limiter that restricts drive transmission from the drive source to the shaft of the reversing roller. The torque limiter is connected to the shaft of the reversing roller when the switched back document is conveyed by the conveying roller. This torque is limited to the torque that the reversing roller rotates with the frictional force with the document, and the one-way clutch is driven only when the shaft of the reversing roller rotates in reverse. The reverse rotation of the shaft of the reversing roller is stopped by stopping the rotation of the driven member by contacting the driven member when the switching member moves to the guide position to the switchback conveyance unit. Automatic document feeder.   The switching member is pivotally supported at a guide position to the switchback conveyance unit or a guide position to the discharge unit, and includes a contact portion that contacts the driven member at one end, and the switching member is connected to the discharge unit. 2. The automatic document feeder according to claim 1, wherein the contact portion comes into contact with the driven member when the guide position is rotated from the guide position to the guide position to the switchback conveying portion.   The automatic document feeder according to claim 2, wherein the driven member is formed with irregularities on the outer periphery thereof, the contact portion includes an elastic deformation member, and the elastic deformation member contacts the outer periphery of the driven member. .   An image forming apparatus comprising the automatic document feeder according to claim 1.

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