JP4444158B2 - Automatic document feeder and image forming apparatus - Google Patents

Description

  The present invention relates to an automatic document feeder and an image forming apparatus.

  In general, as an automatic document feeder that separates a plurality of documents one by one and automatically conveys them to a slit glass, when the documents are set on a document table, the leading edge of the document bundle is aligned and the document bundle is kept at a fixed position. Some are provided with a document stopper claw for preventing the separation performance from being deteriorated by being positioned. Patent Document 1 proposes a technique for reliably driving a document stopper claw in three operating states: an open position, maintenance of the open state, and blocking position.

JP 2001-341879 A

  However, in the prior art described in Patent Document 1, the document stopper claw is driven by the same drive source as the transport roller, and in particular, the discharge roller installed at the last stage of the paper transport path and the drive source have the same configuration. When the motor is returned from the open position to the shut-off position, the motor is driven in reverse. For this reason, if the document discharged to the discharge tray is caught on the discharge roller, the document is transported in the direction opposite to the normal transport direction, and the discharged document is drawn back into the transport path. There was a risk of it.

  The present invention provides an automatic document feeder and an image forming apparatus capable of preventing a discharged document from being drawn into the conveyance path again even when the document stopper claw and the discharge roller are used as the same drive source. It is an object.

  In order to solve the above-mentioned problem, the invention described in claim 1 is movably between a blocking position for blocking the conveyance path of the sheet bundle placed on the sheet loading table and an open position for opening the conveyance path. The document stop claw is provided and a paper discharge roller installed downstream of the paper transport path, and the document stop claw is located at the leading end of the paper bundle placed on the paper platform when transported in the blocking position. The abutment regulates the movement of the sheet bundle downstream in the sheet conveyance direction, and the drive source for the document stop pawl and the drive source for rotationally driving the discharge roller are configured by the same motor. In an automatic document feeder that rotates the motor in the direction opposite to the roller discharge direction to return the document stop pawl from the open position to the shut-off position, when the document stop pawl is returned to the shut-off position, the discharge roller is set in the paper discharge direction. Rotate in the opposite direction Allowed and characterized in that rotating the discharge roller in the paper discharge direction in the same direction at least before or after.

  According to a second aspect of the present invention, in the first aspect of the invention, when the document stop claw is returned from the open position to the blocking position, the discharge roller is rotated in the direction opposite to the discharge direction. After that, the paper discharge roller is rotated in the same direction as the paper discharge direction.

  According to a third aspect of the invention, in the second aspect of the invention, the amount of motor rotation when rotating the paper discharge roller in the same direction as the paper discharge direction is opposite to the rotation direction of the paper discharge roller. It is characterized by being larger than the amount of motor rotation at the time of rotation.

  The invention described in claim 4 is the invention described in claim 2 or 3, wherein the rotational speed of the motor when rotating the discharge roller in the same direction as the discharge direction is the rotation direction of the discharge roller. It is characterized by being slower than the motor rotation speed when rotating in the reverse direction.

  According to a fifth aspect of the present invention, in the first aspect of the invention, when the document stop pawl is returned from the open position to the blocking position, before the paper discharge roller is rotated in the direction opposite to the paper discharge direction. In addition, the paper discharge roller is rotated in the same direction as the paper discharge direction, and the motor rotation amount when the paper discharge roller is rotated in the same direction as the paper discharge direction rotates in the direction opposite to the rotation direction of the paper discharge roller. The motor rotation speed when rotating the paper discharge roller in the same direction as the paper discharge direction is faster than the motor rotation speed when rotating in the direction opposite to the rotation direction of the paper discharge roller. It is characterized by.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, when the document stop claw is returned from the open position to the blocking position, the discharge roller is set in the discharge direction. Is characterized in that the paper discharge roller is rotated in the same direction as the paper discharge direction before rotating in the reverse direction and after the motor is rotated in the direction opposite to the paper discharge direction.

  According to a seventh aspect of the present invention, there is provided the automatic document feeder according to any one of the first to sixth aspects.

  According to the present invention, when the document stop pawl is returned from the open position to the blocking position, the discharge roller is moved in the same direction as the discharge direction in conjunction with the rotation of the motor in the direction opposite to the discharge direction. By rotating the motor also in the direction, it is possible to prevent the document from being conveyed in the direction opposite to the normal conveyance direction when returning the document stop pawl to the blocking position.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a perspective view showing a driving mechanism for a document stop claw and a cam, FIG. 2 is a perspective view showing a driving mechanism for a calling roller, FIG. 3 is a side view showing a driving mechanism for a document stop claw and a cam, and FIG. FIG. 5 is a schematic diagram showing an image forming apparatus provided with the automatic document feeder according to the present invention, and FIG. 6 is a document according to the first embodiment of the present invention. It is a flowchart explaining the return operation | movement of a stop nail | claw.

  As shown in FIG. 5, the image forming apparatus 1 is a copying machine and includes an apparatus main body 1a and an automatic document feeder (hereinafter simply referred to as ADF) 4 provided on the upper part of the apparatus main body 1a. A contact glass 2 and a slit glass 3 having a smaller area than the contact glass 2 are provided on the upper surface of the apparatus main body 1a. The apparatus main body 1a includes a scanner 31, a writing unit 200 that writes image data read by the scanner 31 onto a photosensitive drum, an image forming unit 201, a fixing unit 208, a paper feeding unit 206, and the like.

  Image information of a document read by the scanner 31 is output as image data to a main body control unit (not shown), and the main body control unit is placed on the photosensitive drum 202 constituting the image forming unit 201 by the writing unit 200. An electrostatic latent image is formed, and a visible image of toner is formed on the photosensitive drum 202 by the cooperation of the charging unit 203, the exposure unit 204, and the developing unit 205 constituting the image forming unit 201. .

On the other hand, the transfer sheet fed from the sheet feeding unit 206 is conveyed to the image forming unit 201, and toner is transferred to one surface of the transfer sheet by the transfer unit 207 constituting the image forming unit 201. The transfer sheet on which fixing by 208 is completed is conveyed to the reverse discharge unit 209.
Here, the I path in the reverse paper discharge unit 209 is a straight paper discharge path for the transfer paper to the outside of the image forming apparatus 1, and the II path is a path through which the transfer paper is reversed and discharged in the reverse paper unit 209. , III path after the transfer paper is reversed in the reverse discharge unit 209, after the transfer paper is re-fed to the double-sided tray, the other side of the transfer paper is transferred through the image forming process described above, It is discharged out of the image forming apparatus 1 through the I path.

  The ADF 4 is provided with a document table (paper placement table) 5 on the upper surface, and a document bundle P made up of a plurality of documents can be set on the document table 5 on the back side reference (downstream reference in the document transport direction). ing. A document detection sensor 6 including an optical sensor or the like is provided on the back side of the document table 5. The document detection sensor 6 detects a document set on the document table 5 and outputs detection information to a controller (not shown). It is supposed to be. The controller outputs a paper feed start signal based on the detection information from the sensor 6.

  A calling roller (rotating member) 7 is provided at the front end of the document table 5 (downstream of the document conveyance direction). The calling roller 7 is in contact with the document bundle P and spaced apart from the document bundle P. It swings between positions.

  FIG. 2 is a view showing a swing mechanism of the calling roller 7. In FIG. 2, the calling roller 7 has a rotating shaft 7 a rotatably supported by a bracket 8, and the bracket 8 is fixed to a supporting shaft 9. A lever 10 is fixed to the support shaft 9, and a first protrusion 10 a is formed at one end of the lever 10 in the extending direction. The first protrusion 10 a is a tongue 8 a formed on the bracket 8. Can be engaged.

  A second protrusion 10 b is formed at the other end in the extending direction of the lever 10, and the second protrusion 10 b is in sliding contact with the cam 11. The cam 11 is connected to a link 12, and one end of the link 12 is urged toward the main body 1a by a first spring (connecting member) 13a. The other end of the link 12 is connected to the solenoid 14 via a second spring (connecting member) 13b.

  The solenoid 14 is driven on the basis of an output signal from the controller. When the solenoid 14 is in the ON state, the second spring 13b is pulled against the urging force of the first spring 13a so that the link 12 in FIG. By rotating in the rotation direction, the cam 11 is rotated to lower the second protruding portion 10b, and the calling roller 7 is brought into contact with the document bundle P. In the OFF state, the link 12 is rotated counterclockwise in FIG. 2 by the first spring 13a, thereby rotating the cam 11 to raise the second projecting portion 10b to bring the calling roller 7 into the original bundle. It is designed to be separated from P. That is, the solenoid 14 moves the calling roller 7 between the contact position and the separation position.

  On the other hand, a paper feeding belt 15 is provided on the downstream side in the document conveying direction with respect to the calling roller 7, and this paper feeding belt 15 is bridged by a driving roller 15a and a driven roller 15b, and is rotated clockwise by the driving roller 15a. It is designed to move around. A reverse roller 16 is slidably contacted with the paper feed belt 15 and the reverse roller 16 rotates in a clockwise direction that is a separation direction. Therefore, the uppermost document is separated from the document bundle P conveyed between the paper feed belt 15 and the reverse roller 16.

  The separated original is conveyed to the slit glass 3 via the pull-out driving roller 17 and the pull-out driven roller 18, and the original is detected by a registration sensor 19 a located downstream of the pull-out driving roller 17 and the pull-out driven roller 18. When the leading edge is detected, the controller reverses the sheet feeding motor that drives the calling roller 7, the driving roller 15a, and the pull-out driving roller 17.

  Although not shown, the driving force of the sheet feeding motor is transmitted to the calling roller 7, the driving roller 15a, and the pull-out driving roller 17 through a transmission mechanism including a plurality of gears and a timing belt. Is driven forward, the calling roller 7, the driving roller 15a and the pull-out driving roller 17 are rotated in the document separating direction via the transmission mechanism, and when the paper feeding motor is driven in reverse, the transmission is transmitted via the one-way clutch. Since the driving roller 15a connected to the mechanism is idle, the sheet feeding belt 15 is prevented from idling to separate the next original from the original bundle.

  The document that has been read by the slit glass 3 is nipped between the transport driving roller 20 and the transport driven roller 21 and transported, and then the paper discharge drive roller (paper discharge roller) 22 and the paper discharge driven roller (paper discharge roller) 23. The paper is discharged onto a paper discharge tray 24 sandwiched between the two. The transport drive roller 20 and the paper discharge drive roller 22 are rotated by a paper discharge motor (motor) and a speed reduction mechanism (not shown).

  A paper discharge sensor 19b is provided in the vicinity of the paper discharge driving roller 22, and this paper discharge sensor 19b detects the trailing edge of the original and outputs the original paper discharge information to the controller. On the other hand, an abutting plate 25 that is a document stop claw is provided at the leading end of the document table 5, and the leading end of the document bundle P set on the document table 5 is abutted against the abutting plate 25. ing.

  The abutting plate 25 is formed in an L shape and is fixed to the support shaft 26. A link 27 is attached to the end of the support shaft 26, and one end of the link 27 is urged toward the main body 1a by a first spring 28a. The other end of the link 27 is connected to the solenoid 14 via a second spring 28a.

  When the solenoid 14 is ON, the second spring 28b is pulled against the bias of the first spring 28a to rotate the link 27 in the counterclockwise direction in FIG. The transport path 32 is retracted to an open position where the transport path 32 is opened. Further, in the OFF state, the link 27 is rotated clockwise in FIG. 3 by the first spring 28a, so that the abutting plate 25 protrudes from the retracted position onto the conveyance path 32 so as to block the conveyance path 32. It is supposed to let you.

  That is, the solenoid 14 swings the abutting plate 25 between the open position and the blocking position. Further, a plate-like member 29 is provided at the end of the support shaft 26, and a cam 30 is in sliding contact with the plate-like member 29. The cam 30 is attached to the end of the rotation shaft 22 a of the paper discharge drive roller 22 and rotates with the rotation of the paper discharge drive roller 22. The cam 30 is connected to the rotary shaft 22a via a torque limiter, and the cam 30 is idle when the roller 22 rotates with a load capable of transporting a document.

  When the cam 30 is rotated to a predetermined position, the protruding cam surface 30a is engaged with the stopper portion 29a of the plate-like member 29, and at this time, the abutting plate 25 is maintained in the open position. Thus, the position at the blocking position is restricted. In the present embodiment, the cam 30 and the plate-like member 29 constitute a stopper member.

  A document detection sensor 6 provided on the document table 5 detects the presence or absence of a document on the document table 5 and outputs detection information to the controller. The controller detects the document based on the detection information from the document detection sensor 6. When it is determined that there is no document on the table 5, the paper discharge motor is driven to return the abutting plate 25 to the blocking position.

  The registration sensor 19a and the paper discharge sensor 19b detect the document on the conveyance path and output detection information to the controller. The controller retains the document on the conveyance path for a predetermined time or more based on the detection information. In this case, it is determined that a jam has occurred, and the paper discharge motor is driven to keep the abutting plate 25 in the open position.

  In the present embodiment, the document detection sensor 6, the registration sensor 19a, the paper discharge sensor 19b, and the controller constitute a paper detection unit.

  On the other hand, the image forming apparatus 1 below the slit glass 3 is provided with a scanner 31 composed of an image sensor, and the scanner 31 is moved in the left-right direction in FIG. 1 by a driving device (not shown). The driving device is controlled by a main body control unit (not shown). When reading image information of a document set on the contact glass 2, a scanner 31 is scanned below the contact glass 2 and a slit is formed. When reading the image information of the document conveyed on the glass 3, the scanner 31 is stopped below the slit glass 3.

  Next, the operation and effect of the automatic document feeder according to the present embodiment will be described. First, a method for conveying a document will be described. When the document bundle P is set on the document table 5, the document detection sensor 6 detects the document bundle P and outputs a paper feed start signal to the controller. At this time, the controller turns on the solenoid 14. When the solenoid 14 is turned on, the second spring 13b is pulled against the urging force of the first spring 13a, and the link 12 is rotated in the clockwise direction in FIG. The protruding portion 10b is lowered to bring the calling roller 7 into contact with the document bundle P.

  At this time, the solenoid 24 simultaneously pulls the second spring 28b against the bias of the first spring 28a and rotates the link 27 in the counterclockwise direction in FIG. The path 32 is retracted to an open position where the path 32 is opened.

  Next, the feeding roller 7, the driving roller 15a, and the pull-out driving roller 17 are rotated by the paper feeding motor, and the conveyance driving roller 20 and the paper discharging driving roller 22 are rotated by the paper discharging motor. The original is separated and conveyed to the slit glass 3 which is a reading position. Further, when the leading edge of the document is detected by the registration sensor 19a, the solenoid 14 is turned off.

  At this time, the link 12 is rotated counterclockwise in FIG. 2 by the first spring 13a, thereby rotating the cam 11 and raising the second protrusion 10b to separate the calling roller 7 from the document bundle P. . At the same time, the link 27 is rotated clockwise by the first spring 28a to rotate the cam 30 so that the abutting plate 25 protrudes from the retracted position onto the conveyance path 32 so as to block the conveyance path 32. I am doing so. At this time, since the cam surface 30a of the cam 30 abuts against the stopper portion 29a by the rotating shaft 22a rotated by the paper discharge motor, the abutment plate 25 is restricted from being returned to the blocking position and positioned at the open position. It remains in the state. At this time, since the paper feed motor is driven in the reverse direction, it is possible to prevent the driving roller 15a from rotating idle and separating the subsequent document by the paper feed belt 15.

  Then, the document that has been read is discharged onto the discharge tray 24 by the conveyance drive roller 20 and the discharge drive roller 22. When the trailing edge of the document is detected by the registration sensor 19a, if it is determined that there is still a document on the document table 5 based on the detection information from the document detection sensor 6, the solenoid 14 is turned on to call the roller. 7 is brought into contact with the original bundle P, and the paper feeding motor is driven to rotate forward to separate subsequent originals.

  On the other hand, when it is determined that the original on the original table 5 has run out based on the detection information from the original detection sensor 6, the solenoid 14 is kept OFF. The link 27 is to be rotated in the clockwise direction in the drawing by the first spring 28a. At this time, the cam surface 30a of the cam 30 is engaged with the stopper portion 26a, so that the abutting plate 25 is positioned at the open position. Will remain. Then, after discharging the document in the transport path, the discharge motor is driven in reverse to reversely rotate the rotating shaft 22a, whereby the cam 30 is rotated in reverse to separate the cam surface 30a from the stopper portion 26a. The link 27 is rotated in the clockwise direction in FIG. 1 by the urging force of 28a, so that the abutting plate 25 moves to the blocking position protruding on the transport path 32 and returns to the original state. The returning operation of the butting plate 25 is performed as an initial operation when the image forming apparatus 1 is turned on.

  Next, the returning operation of the butting plate 25 according to the present embodiment will be described. Although the abutting plate 25 is performed by reverse rotation of a paper discharge motor (not shown), the original discharged from the conveyance path may not be completely discharged from the discharge driven roller 23 depending on the discharge speed, the original thickness, and the like. In this state, when the paper discharge motor is reversed as a return operation of the butting plate 25, the original that has not been completely discharged from the paper discharge driven roller 23 due to the reverse rotation of the paper discharge roller is again drawn into the conveyance path. There is a risk of being lost.

  In the present embodiment, the discharge motor is rotated in the forward direction (conveyance direction) in conjunction with the return operation of the abutting plate 25 as an operation of preventing the original from being drawn into the conveyance path and discharging the original that has been drawn in. Rotate. The returning operation of the abutting plate 25 is performed when the image forming apparatus 1 is turned on and when a paper supply cover (not shown) covering from the separation unit to the reading unit is opened and closed. The registration sensor 19 and the paper discharge sensor 19b are used for the original in the conveyance path. After confirming the presence or absence, the position fixing initial operation of the abutting plate 25 is performed.

  In this state, it is difficult to assume the presence or absence of a document in the conveyance path and the state of the paper discharge driven roller 23 and the paper discharge tray 24. Therefore, the rear end of the document exists in the vicinity of the paper discharge rollers 22 and 23, and importance is attached to the possibility that the document is drawn into the conveyance path by the reverse rotation driving of the paper discharge roller. After the paper discharge rollers 22 and 23 are reversed, the paper discharge motor is driven in the forward rotation direction (steps S11 to S16). Note that the motor rotation amount when driving the paper discharge motor in the forward direction is larger than the motor rotation amount when driving the paper discharge motor in the reverse direction for the return operation of the abutting plate 25. . Further, the motor rotation speed when rotating the paper discharge rollers 22 and 23 in the same direction as the paper discharge direction is slower than the motor rotation speed when rotating in the opposite direction to the rotation direction of the paper discharge rollers 22 and 23. I have to.

  As described above, according to the present embodiment, when the abutting plate 25 is returned from the open position to the blocking position, the discharge rollers 22 and 23 are rotated in the direction opposite to the discharge direction. By rotating the paper discharge rollers 22 and 23 in the same direction as the paper discharge direction, when the abutting plate 25 is returned to the blocking position, it is possible to prevent the original from being caught on the end of the paper discharge roller. Even when the paper is caught on the end of the paper roller, the paper discharge rollers 22 and 23 can be rotated in the same direction as the paper discharge direction to prevent the original from being conveyed in the direction opposite to the normal conveyance direction.

  Further, the amount of motor rotation when driving the paper discharge motor in the forward direction is larger than the amount of motor rotation when driving the paper discharge motor for reverse operation of the abutting plate 25 in the reverse direction. Therefore, even if the document on the end of the paper discharge roller is transported in the direction opposite to the normal transport direction, the document is transported in the normal transport direction more than the transport amount transported in the reverse direction. Thus, the document can be completely discharged onto the discharge tray 24 without the trailing edge of the document being applied to the end of the discharge roller.

  When the document is drawn into the conveyance path, the drawn document may be inclined with respect to the conveyance direction, but a motor for rotating the discharge rollers 22 and 23 in the same direction as the discharge direction. Since the rotation speed is slower than the motor rotation speed when rotating in the direction opposite to the rotation direction of the paper discharge rollers 22 and 23, the unstable behavior of the document that has been pulled in in an unstable state occurs. Time can be relaxed and the original document can be protected.

  Next, other embodiments will be described. In the following description, parts having the same functions and effects as those of the first embodiment described above are denoted by the same reference numerals, and detailed description of the parts is given. In the following description, differences from the first embodiment will be mainly described. FIG. 7 is a flowchart for explaining the returning operation of the butting plate 25 according to the second embodiment.

  In the return operation of the butting plate 25 after the document is discharged in the normal reading operation, the document is discharged in the transport direction until just before the return operation, so there is no document in the transport path, and the discharged document is also discharged by the discharge roller. The risk of hanging on the edge is small. In addition, since the document reading operation is normally completed and preparation for the next document bundle set on the document table 5 needs to be made immediately, the operation of returning the abutting plate 25 is performed as a pull-in preventing operation. Before the paper discharge rollers 22 and 23 are rotated in reverse, the paper discharge motor is driven in the forward rotation direction (steps S21 to S26).

  The motor rotation amount when rotating the paper discharge rollers 22 and 23 in the same direction as the paper discharge direction is made smaller than the motor rotation amount when rotating the paper discharge rollers 22 and 23 in the direction opposite to the rotation direction. Therefore, the driving time of the motor can be shortened, and the preparation time for the next document bundle set on the document table 5 can be shortened.

  The motor rotation speed when rotating the paper discharge rollers 22 and 23 in the same direction as the paper discharge direction is faster than the motor rotation speed when rotating in the opposite direction to the rotation direction of the paper discharge rollers 22 and 23. The document can be discharged quickly.

  Next, the returning operation of the butting plate according to the third embodiment will be described. When a document jam occurs in the transport path, if the return operation of the butting plate 25 is performed after processing the generated document jam, there is a possibility that there is a document that has not yet been jammed in the transport path. Then, there is a possibility that the stacked state of the discharged document is changed by manipulating the discharged document by the operator, and the document is moved in the vicinity of the discharged rollers 22 and 23.

  In the present embodiment, before the paper discharge rollers 22 and 23 are rotated in the direction opposite to the paper discharge direction and after the paper discharge roller is rotated in the direction opposite to the paper discharge direction, the paper discharge rollers are moved in the paper discharge direction. It is rotated in the same direction (steps S31 to S38). Thus, by rotating the paper discharge motor forward and backward before and after the returning operation of the butting plate 25, it is possible to both prevent the original from being pulled in and discharge the original that has been pulled in.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. In the third embodiment, the forward rotation speed of the paper discharge motor at the time of jam processing should be as low as possible in order to further protect the jammed paper.

  In the first to third embodiments, the normal rotation timing of the paper discharge motor with respect to the returning operation of the abutting plate 25 is determined when the power is turned on, when the cover is opened / closed, when the normal reading operation is completed, and when the jam processing is performed. It may be done at other times.

It is a perspective view which shows the drive mechanism of a document stop nail | claw and a cam. It is a perspective view which shows the drive mechanism of a calling roller. FIG. 6 is a side view showing a document stop claw and a cam drive mechanism. 1 is a schematic configuration diagram of an automatic document feeder according to the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus including an automatic document feeder according to the present invention. It is a flowchart explaining the return operation | movement of the document stop nail | claw based on 1st Embodiment of this invention. It is a flowchart explaining the return operation | movement of the document stop nail | claw based on 2nd Embodiment of this invention. It is a flowchart explaining the return operation | movement of the document stop nail | claw based on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Automatic document feeder 5 Document table (paper mounting table)
22 Paper ejection drive roller (paper ejection roller)
23 Paper discharge driven roller (paper discharge roller)
25 Butting plate (document stop claw)

Claims (7)

  A document stop claw movably provided between a blocking position for blocking the conveyance path of the sheet bundle placed on the sheet placement table and an open position for opening the conveyance path, and a paper discharge set downstream of the paper conveyance path. And a document stop claw that restricts the sheet bundle from moving downstream in the sheet conveying direction by abutting against the leading end of the sheet bundle placed in the sheet loading table when the document stop claw is positioned at the blocking position. The drive source for the document stop claw and the drive source for rotating the discharge roller are configured by the same motor, and the document stop claw is opened by rotating the motor in the direction opposite to the discharge direction of the discharge roller. In the automatic document feeder for returning from the position to the blocking position, when the document stop claw is returned to the blocking position, the discharge roller is rotated in the direction opposite to the discharge direction and at least before or after the discharge roller is discharged. Paper direction and Automatic document feeding apparatus, wherein the rotating direction.   When returning the document stop pawl from the open position to the blocking position, the discharge roller is rotated in the opposite direction to the discharge direction, and then the discharge roller is rotated in the same direction as the discharge direction. The automatic document feeder according to claim 1.   The motor rotation amount when rotating the paper discharge roller in the same direction as the paper discharge direction is larger than the motor rotation amount when rotating the paper discharge roller in the direction opposite to the rotation direction of the paper discharge roller. Automatic document feeder.   The motor rotation speed when the motor is rotated in the same direction as the paper discharge direction of the paper discharge roller is slower than the motor rotation speed when the motor is rotated in a direction opposite to the rotation direction of the paper discharge roller. Item 4. The automatic document feeder according to Item 2 or 3.   When returning the document stop pawl from the open position to the blocking position, the paper discharge roller is rotated in the same direction as the paper discharge direction before the paper discharge roller is rotated in the direction opposite to the paper discharge direction. The motor rotation amount when rotating the paper roller in the same direction as the paper discharge direction is smaller than the motor rotation amount when rotating the paper roller in the direction opposite to the rotation direction of the paper discharge roller, and the paper discharge roller is in the same direction as the paper discharge direction. 2. The automatic document feeder according to claim 1, wherein the motor rotation speed when the sheet is rotated is faster than the motor rotation speed when the sheet discharge roller is rotated in the direction opposite to the rotation direction.   When returning the document stop pawl from the open position to the blocking position, the paper discharge roller is rotated in the direction opposite to the paper discharge direction and after the paper discharge roller is rotated in the direction opposite to the paper discharge direction. 6. The automatic document feeder according to claim 1, wherein the paper roller is rotated in the same direction as the paper discharge direction. An image forming apparatus comprising the automatic document feeder according to claim 1.

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