JP2011230906A - Automatic document feeder and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic document feeder that can read a non-warped image by controlling the release and restoration of a separation function of a separation means in proper timing, thereby keeping intervals between paper constant, maintaining high productivity, reducing a cause for a document skew and improving stability in feeding a document, and to provide an image forming apparatus.SOLUTION: A reverse roller 10 moves between a separation position that comes into press-contact with a feed roller 9 and a separation releasing position that is separated from the feed roller 9 by an arm 10a and a cam member 10q. The reverse roller 10 is moved to the separation releasing position after an end of the document passes by the a separation part 401, and the reverse roller 10 is returned to the separation position before the next document is fed to the separation part 401.

Description

  The present invention relates to an automatic document conveying device and an image forming apparatus, and more particularly to an automatic document conveying device that separates and conveys a single document from a document bundle and an image forming apparatus including the automatic document conveying device.

  Conventionally, this type of automatic document feeder is a so-called sheet-through type automatic document in which a single document separated from a bundle of documents is exposed and read by a fixed reading unit while being conveyed at a predetermined speed. A conveying device is known. Since the sheet-through type automatic document feeder is a mechanism that reads an image while conveying a document, it can increase productivity compared to a type (book type) that reads and reads a stopped document. It is one of. Today, where work efficiency is demanded, productivity is improved, that is, the speed of reading a document is accelerated.

  In a sheet-through type automatic document feeder, it is necessary to read a non-bent image, and for this purpose, it is required to convey the document without bending (skewing).

  However, when separating one original from the original bundle, the separation unit applies a force in the feeding direction to the uppermost original in the original bundle and applies a returning force to the second and subsequent originals. Therefore, the conveyance balance is likely to be lost, and document bending (hereinafter referred to as skew) is likely to occur. That is, a moment that causes the document to skew is easily generated by the force in the feeding direction and the force in the returning direction.

  In addition, even after passing through the separation, the conveying force of each conveying means (conveying roller) may be biased with respect to the main scanning direction due to variations in each part. Therefore, it has been a problem for reading an image without bending.

  In response to these problems, a document abutting means for correcting the orientation of the document is provided downstream of the separation unit or in the vicinity of the reading unit, and the document is abutted against the document abutting unit. A technique for correcting the skew is known (see, for example, Patent Document 1 or Patent Document 2).

  However, even if the skew of the document is corrected by a method such as Patent Document 1 or Patent Document 2, if a subsequent variation in the conveyance force occurs, the corrected document starts to bend again and again before reaching the reading unit. There may be a skew.

  According to the configuration so far, in addition to the variation in the main scanning direction of the conveying means at the component level, the separating means becomes a conveying resistance against the conveying force by the conveying means, which causes a problem of skew.

  In particular, in the case of a configuration in which the document bundle is set with reference to the end face, depending on the document size, the conveyance resistance due to the separating unit may be asymmetrical with respect to the feed direction, which causes the balance of the conveyance force to be lost and skew. Causes the occurrence. In the case of a configuration in which the document bundle is set with the central reference, the separating unit basically maintains the target shape, but there is a risk that the document may be skewed due to variations in pressure balance at the component level. .

  In the case of the central reference, setting the side fence appropriately at the time of setting the document is the basis for preventing skew, but depending on the user, it may not always comply, and the side fence can be set asymmetrically, Or, there is a case where the original is set so that a gap is generated with respect to the original. In this case, the original is in an asymmetrical balance with respect to the separating means, and thus has the same problem as the end face reference. It becomes.

  In addition, since the automatic document feeder has a conveyance resistance due to the separation load, it is necessary to separately apply a conveyance force that can overcome the conveyance resistance. In order to obtain the conveying force necessary for this, it is necessary to increase the pressure of the roller, and it is necessary to increase the rigidity of the members around the roller. Issues exist regardless of manuscript standards.

  On the other hand, the technique of releasing the separation unit from the pressurized state is used for reasons such as document jam processing. Since the separation pressure of the separation unit is released during the conveyance after the original reaches the separation unit, the conveyance resistance due to the separation load is eliminated, so that an effect of suppressing skew is expected.

  By the way, when pursuing high productivity, it is necessary to reduce the space between the originals as short as possible. However, when such a configuration is adopted, the timing of feeding the next original after the pressure release of the separation unit is released. It takes time to apply the separation pressure again until it comes, and as a result, the gap between the papers becomes long, which becomes a problem in the case of trying to pursue high productivity.

  On the other hand, there is known a configuration in which the pressure of the separating unit can be released for the purpose of improving the document conveyance stability (see, for example, Patent Document 3).

  That is, normally, the separating member is elastically biased in the direction of the rotation axis of the paper feed roller, and the swinging piece is formed with a protruding piece that engages with an engaging member that is slidably attached. Yes. Also, when reading a document that requires high quality, the separation member is swung in a direction away from the paper feed roller by sliding the engagement member engaged with the separation member, and the conveyance is performed. The document inside is not subjected to conveyance resistance due to a separation load, and skew is prevented.

  However, in the technique described in Patent Document 3, by releasing the separation load, it is possible to prevent skew and ensure document conveyance stability, but manually separate the separation member from the paper feed roller in advance. Since it is necessary to separate them, it takes time to release or re-apply the separation pressure, and there is a problem that productivity is lowered.

  The present invention has been made to solve the above-described conventional problems. By controlling the release and return of the separating function of the separating means at an appropriate timing, the gap between the sheets can be kept short and high productivity can be achieved. It is an object of the present invention to provide an automatic document feeder and an image forming apparatus that can maintain the document skew, improve the document conveyance stability by reducing the cause of document skew, and realize image reading without bending.

  An automatic document feeder according to the present invention includes a document placing unit that places a bundle of documents composed of a plurality of documents, and a sheet feeding unit that feeds the topmost document from the document bundle placed on the document placing unit. Means, separating means for separating the document fed by the feeding means, transport means for transporting the document separated by the separating means to a predetermined reading position, and the document that has been read at the reading position In the automatic document feeder provided with a paper discharge unit for discharging paper, the separating unit is in contact with one surface of the document to move the document in the transport direction and to the other surface of the document. A regulating member that regulates movement of the document in the conveyance direction, and that displaces the regulating member between a separation position that is pressed against the conveyance member and a separation release position that is separated from the conveyance member Means and the leading edge of the document After passing the separating means, the restricting member displacing means is driven to displace the restricting member to the separation release position, and before the next document is fed to the separating means, the restricting member displacing means is moved. Control means for driving and displacing the restricting member to the separation position.

  With this configuration, after the original is separated, the regulating member is moved to the separation release position and the original is conveyed, so that no separation load is applied to the original, so that the conveying force in the main scanning direction of the conveying means downstream thereof is balanced. As a result, the skew of the original is suppressed, and the conveyance stability is improved.

  In addition, the timing at which the regulating member returns from the separation release position to the separation position is controlled so that the next document is fed before the next document is fed to the separation unit, thereby keeping the paper interval short and keeping the productivity high. Is possible.

  Therefore, the release and return of the separating function of the separating means is controlled at an appropriate timing to maintain high productivity by keeping the paper interval short and to reduce the cause of document skew to improve document conveyance stability and prevent bending. No image reading can be realized.

  The automatic document feeder according to the present invention further includes a first document detection unit that is disposed in the vicinity of the downstream side of the separation unit in the document conveyance direction and detects the passage of the end of the document. The restricting member displacing means is driven by using the leading edge of the first document detecting means as a trigger to displace the restricting member to the separation release position.

  With this configuration, the release and return of the separation function of the separation means are controlled at an appropriate timing.

  The automatic document feeder according to the present invention further includes a second document detection unit that is disposed downstream of the first document detection unit in the document conveyance direction and detects passage of an end of the document. The regulating member is displaced from the separation release position to the separation position after the trailing edge of the document has passed through the first document detection means or after the leading edge of the document has passed through the second document detection means. The restricting member displacing means is driven to displace the restricting member to the separation position at an earlier timing by the time required to do so.

  With this configuration, the regulating member displacing means is driven to displace the regulating member to the separating position at an earlier timing by the time required for the regulating member to be displaced from the separation release position to the separating position. Before the sheet is fed, the restricting member can be surely displaced to the separation position.

  Further, the automatic document feeder according to the present invention feeds a topmost document from a document placing means for placing a document bundle composed of a plurality of documents, and a document bundle placed on the document placing means. Reading is completed at the reading position, feeding means, separating means for separating the document fed by the feeding means, conveying means for feeding the document separated by the separating means to a predetermined reading position, and In the automatic document feeder provided with a paper discharge means for discharging a document, the separating means contacts the one surface of the document and moves the document in the transport direction, and the other surface of the document. A restricting member that contacts and restricts movement of the document in the conveying direction, and a restricting member control unit that controls the rotation direction and torque of the restricting member; and after the leading end of the document passes through the separating unit, By the control member control means Control means for rotating the regulating member in the document conveying direction and for causing the regulating member control means to rotate the regulating member in a direction opposite to the document conveying direction before the next document is fed to the separating means; , Provided.

  With this configuration, by rotating the regulating member in the document conveyance direction after separating the document, a separation load is not applied to the document, so that the conveyance force in the main scanning direction of the conveyance unit downstream thereof is kept balanced, The skew of the original can be suppressed and the conveyance stability is improved.

  In addition, the timing at which the rotation direction of the regulating member returns from the document conveying direction to the direction opposite to the document conveying direction is controlled so that it is before the next document is fed to the separating unit, thereby shortening the sheet interval. It is possible to maintain high productivity.

  Therefore, the release and return of the separating function of the separating means is controlled at an appropriate timing to maintain high productivity by keeping the paper interval short and to reduce the cause of document skew to improve document conveyance stability and prevent bending. No image reading can be realized.

  The automatic document feeder according to the present invention further includes a first document detection unit that is disposed in the vicinity of the downstream side of the separation unit in the document conveyance direction and detects the passage of the end of the document. The restricting member is rotated by the restricting member control means in a direction opposite to the document conveying direction with a leading edge passing through the first document detecting means as a trigger.

  With this configuration, the release and return of the separation function of the separation means are controlled at an appropriate timing.

  The automatic document feeder according to the present invention further includes a second document detection unit that is disposed downstream of the first document detection unit in the document conveyance direction and detects passage of an end of the document. After the trailing edge of the document has passed through the first document detection means or after the leading edge of the document has passed through the second document detection means, the rotation direction of the regulating member is the direction opposite to the document conveyance direction The regulating member control means rotates the regulating member in the direction opposite to the document carrying direction at a timing earlier by the time required for the change from the document feeding direction to the document carrying direction.

  With this configuration, the restricting member is moved in the direction opposite to the original conveying direction by the restricting member control means at a timing earlier than the time required for the rotation direction of the restricting member to change from the direction opposite to the original conveying direction to the original conveying direction. Since the rotation is performed, the rotation direction of the regulating member can be reliably changed to the direction opposite to the document conveyance direction before the next document is fed to the separating unit.

  In addition, an image forming apparatus according to the present invention includes the above-described automatic document feeder.

  With this configuration, even in the image forming apparatus provided with the automatic document feeder, release and return of the separating function of the separating unit are controlled at an appropriate timing, while maintaining high productivity by keeping the interval between sheets short, It is possible to reduce the cause of document skew, improve document conveyance stability, and realize image reading without bending.

  According to the present invention, release and return of the separating function of the separating means are controlled at an appropriate timing to maintain high productivity by keeping the paper interval short, and reduce the cause of document skew and improve document conveyance stability. It is possible to provide an automatic document feeder and an image forming apparatus which can improve and realize image reading without bending.

1 is a configuration diagram of an automatic document feeder according to a first embodiment of the present invention. FIG. 2 is a block diagram of a control system of the automatic document feeder according to the first embodiment of the present invention. FIG. 1 is a block diagram illustrating a configuration of an image reading unit of an automatic document feeder according to a first embodiment of the present invention. FIG. 6 is a top view illustrating an influence on separation due to a separation load for a document being separated and conveyed by the automatic document conveyance device according to the first exemplary embodiment of the present invention. FIG. 6 is a top view illustrating an influence on separation due to a separation load for a document being separated and conveyed by the automatic document conveyance device according to the first exemplary embodiment of the present invention. FIG. 3 is a cross-sectional view of a separation unit for explaining separation load change due to separation of a reverse roller in the automatic document feeder according to the first exemplary embodiment of the present invention. FIG. 3 is a cross-sectional view of a reverse roller for explaining separation load change by reverse roller separation of the automatic document feeder according to the first embodiment of the present invention. FIG. 4 is a side view of a separation unit for explaining a separation load change due to reverse roller separation in the automatic document feeder according to the first embodiment of the present invention. 3 is a cross-sectional view illustrating a state where a reverse roller of a separation unit of the automatic document feeder according to the first embodiment of the present invention is in contact with a paper feed belt. FIG. FIG. 3 is a cross-sectional view illustrating a state where a reverse roller of a separation unit of the automatic document feeder according to the first exemplary embodiment of the present invention is separated from a paper feed belt. It is sectional drawing of the separation part explaining the trigger at the time of reviving the separation function of the automatic document feeder which concerns on the 1st Embodiment of this invention. It is sectional drawing of the separation part explaining the trigger at the time of reviving the separation function of the automatic document feeder which concerns on the 1st Embodiment of this invention. It is sectional drawing of the isolation | separation part explaining the other example of the trigger at the time of reviving the isolation | separation function of the automatic document feeder based on the 1st Embodiment of this invention. It is sectional drawing of the isolation | separation part explaining the other example of the trigger at the time of reviving the isolation | separation function of the automatic document feeder based on the 1st Embodiment of this invention. (A), (b) is another example of the separation unit of the automatic document feeder according to the first embodiment of the present invention, and is a cross-sectional view of a configuration in which document separation is performed by a feed roller and a separation pad. is there. FIG. 3 is a cross-sectional view of a separation unit of the automatic document feeder according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of a separation unit of the automatic document feeder according to the first embodiment of the present invention. FIG. 5 is a flowchart for explaining the operation of the automatic document feeder according to the first embodiment of the present invention. It is sectional drawing of the separation part explaining the separation load control using the motor of the automatic document feeder concerning the 2nd Embodiment of this invention. FIG. 10 is a side view of a separation unit for explaining separation load control using a motor of an automatic document feeder according to a second embodiment of the present invention. FIG. 10 is a flowchart illustrating a schematic operation of separation load control using a motor of an automatic document feeder according to a second embodiment of the present invention. FIG. 10 is a flowchart illustrating a detailed operation of an automatic document feeder according to a second embodiment of the present invention. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, the configuration will be described.

  As shown in FIG. 1, the automatic document feeder 50 includes a document table 2 on which a document bundle 1 composed of a plurality of documents is placed with the document surface facing upward, and a document bundle 1 placed on the document table 2. A pickup roller 7 that conveys the uppermost document, a paper feed belt 9 and a reverse roller 10 that separate the document conveyed by the pickup roller 7, and a single separated document as a slit in the image forming apparatus main body 60. A pull-out roller 12, an intermediate roller 14, and a reading entrance roller 16 that conveys to the vicinity of the glass 21, a reading roller 19 that conveys the document conveyed to the vicinity of the slit glass 21 while making contact with the slit glass 21, A reading exit roller 23 that further conveys the document that has been read at the reading position 20, and is conveyed by the reading exit roller 23. A paper discharge roller 28 for discharging the original document, and a paper discharge tray 29 ejected documents is placed.

  The intermediate rollers 14 convey the documents conveyed by the pull-out roller 12 into the turn portion D, and are arranged in a plurality of rows along the direction orthogonal to the document conveyance direction at the upstream portion of the turn portion D in the document conveyance direction. Yes. The intermediate roller 14 constitutes a first conveying unit in the present invention.

  The reading entrance rollers 16 convey the originals transported from the turn part D to the vicinity of the slit glass 21, and are arranged in a plurality of rows along the direction orthogonal to the original conveyance direction at the downstream part of the turn part D in the original conveyance direction. Has been. The reading entrance roller 16 constitutes a second conveying unit in the present invention.

  The document placed on the document table 2 passes through each part of the transport path before being discharged to the discharge tray 29. The conveyance path includes a document setting unit A on which the document bundle 1 is placed, a separation feeding unit B that separates and feeds one document from the placed document bundle 1, and a feeding document. A registration unit C that draws and conveys a document after alignment, a turn unit D that turns the conveyed document and conveys the document surface downward, and a surface of the document. A first reading conveyance unit E that reads from below the slit glass 21, a second reading conveyance unit F that reads the back side of the document, a paper discharge unit G that discharges the document whose front and back sides have been read out, and a discharge unit G And a stack portion H on which a document is placed. Here, the front surface of the document refers to the surface that faces upward on the document table 2 and is read by the first reading / conveying section E, and the back surface of the document faces downward on the document table 2 and corresponds to the second reading / conveying section F. This is the surface where reading is performed.

  The turn part D constitutes a part of a document transport path from the document table 2 to the paper discharge tray 29, and is a curved path curved so as to change (reverse) the document transport direction by approximately 180 °. Outer guide members 261 and 262 for guiding the conveyance of the document in the turn part D are arranged outside the turn part D, and the document in the turn part D is conveyed in the curve part of the turn part D. An inner guide member 252 for guiding is arranged.

  As shown in FIG. 2, the automatic document feeder 50 includes a controller 100 that controls the entire automatic document feeder 50. The automatic document feeder 50 also includes a registration sensor 17, a document set sensor 5, a paper discharge sensor 24, an abutment sensor 11, a document width sensor 13, a reading entrance sensor 15, a sensor for inputting a signal to the controller 100. A paper proper position sensor 8 and a home position sensor 6 are provided. The automatic document feeder 50 also includes a second reading unit 25, a pickup lifting / lowering motor 101, a paper feeding motor 102, a reading motor 103, a paper discharging motor 104, and a bottom plate as actuators that are driven and controlled by outputting signals from the controller 100. A lift motor 105 is provided.

  The image forming apparatus main body 60 includes a main body control unit 111 that controls the image forming apparatus main body 60 and an operation unit 108 that performs various input operations and operation instructions. The controller 100 and the main body control unit 111 are connected via the I / F 107, and data such as a control signal is exchanged between them.

  As shown in FIG. 3, the second reading unit 25 includes a light source unit 200 that irradiates light on a document based on a lighting signal from the controller 100, a plurality of sensor chips 201 that receive reflected light from the document, A plurality of amplifying units 202 that amplify signals output from the sensor chip 201, an A / D conversion unit 203 that converts the amplified signals from analog signals to digital signals, and an image that performs image processing on the digitally converted signals A processing unit 204, a frame memory 205 that stores the image-processed signal, an output control circuit 206 that controls output of the signal stored in the frame memory 205 based on a timing signal from the controller 100, and an output control circuit 206 And an I / F circuit 207 for outputting a signal from the main body control unit 111. The second reading unit 25 is supplied with power from the controller 100.

  Here, the detailed configuration of the automatic document feeder 50 will be described according to the order in which the documents placed on the document table 2 are discharged to the discharge tray 29.

  First, a document bundle 1 composed of a plurality of documents is placed on a document table 2 including a movable document table 3 with the surface facing upward. Next, the position in the width direction of the document bundle 1, that is, the position in the direction orthogonal to the conveyance direction is positioned by a side guide (not shown). The placement of the document on the document table 2 is detected by the set filler 4 and the document set sensor 5, and a detection signal is output to the main body control unit 111 of the image forming apparatus main body 60 via the I / F 107.

  An outline of the length of the document in the conveyance direction is detected by document length detection sensors 30 and 31 provided on the surface of the document table 2. As the document length detection sensors 30 and 31, a reflection type sensor that detects without contact with the document by optical means or a contact type actuator that can detect even when there is only one document can be used. . The document length detection sensors 30 and 31 are arranged so that it can be determined whether the document is placed vertically or horizontally.

  The movable document table 3 is configured to move up and down in the directions of arrows a and b in FIG. When it is detected by the set filler 4 and the document set sensor 5 that the document is placed on the document table 2, the controller 100 rotates the bottom plate raising motor 105 in the normal direction so that the uppermost document in the document bundle 1. The movable document table 3 is raised so as to come into contact with the pickup roller 7. Hereinafter, the position where the uppermost document of the document bundle 1 contacts the pickup roller 7 is referred to as an appropriate feeding position.

  The pickup roller 7 is operated in the directions of arrows c and d in FIG. 1 by a pickup raising / lowering motor 101 via a cam mechanism, and is pushed by the document on the raised movable document table 3 and lifted in the direction of arrow c to feed paper. The upper limit of movement is detected by the appropriate position sensor 8. The proper paper feed position sensor 8 is a sensor for detecting that the movable original table 3 is raised and the uppermost original of the original bundle 1 is maintained at an appropriate height.

  When the operation unit 108 is operated to specify either the double-side mode or the single-side mode, the print key is pressed, and a document feed signal is output from the main body control unit 111 to the controller 100 via the I / F 107. The controller 100 rotates the pickup roller 7 by rotating the paper feed motor 102 forward. The pick-up roller 7 that has started rotating picks up the uppermost document on the document table 2 or several documents including the uppermost document.

  Next, when the paper feeding motor 9 is rotated forward by driving the paper feeding belt 9 and the reverse roller 10 clockwise, the paper feeding belt 9 guides the original in the paper feeding direction, and the reverse roller 10 sets the original in the paper feeding direction. Since the document is pushed out in the opposite direction, the uppermost document in the document bundle 1 and the document below it are separated, and only the uppermost document is fed.

  Specifically, the reverse roller 10 is in contact with the paper feed belt 9 at a predetermined pressure, and in the state of being in direct contact with the paper feed belt 9 or in the state of being in contact with one original, the paper feed belt 9. 9 is rotated in a counterclockwise direction different from the original driving direction by the action of a torque limiter (not shown). Further, when two or more documents enter between the paper feed belt 9 and the reverse roller 10, the reverse roller 10 does not rotate with the paper feed belt 9, but rotates in the clockwise direction, which is the original driving direction. It works to push back excess originals and prevent double feeding.

  The original separated by the action of the paper feeding belt 9 and the reverse roller 10 is sent by the paper feeding belt 9, and then the leading edge of the original is detected by the abutting sensor 11, and further conveyed and stopped. The pull-out roller 12 is in contact with the pull-out roller 12. Next, when the original fed by a predetermined distance from the position detected by the abutting sensor 11 is pressed against the pull-out roller 12 with a predetermined amount of deflection, the paper feed motor 102 is stopped and the paper feed belt 9 is stopped. The drive stops. At this time, by rotating the pickup lifting / lowering motor 101, the pickup roller 7 is raised and retracted from the upper surface of the document, and the document is fed only by the conveying force of the paper feed belt 9, so that the leading edge of the document is held by the pull-out roller 12. Thus, tip alignment, so-called skew correction is performed. The pull-out roller 12 has a skew correction function and is used to convey the skew-corrected document after separation to the intermediate roller 14 and is driven by the reverse rotation of the paper feed motor 102. When the paper feed motor 102 rotates in the reverse direction, the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and the paper feed belt 9 are not driven.

  The document width sensor 13 is composed of a plurality of photoelectric conversion elements such as a contact image sensor called CIS arranged in a direction perpendicular to the document transport direction, and is not shown in the figure disposed at the opposite portion of the transport path. The light reception level of the direct light emitted from the irradiation light source is output. When the document passes the position of the document width sensor 13, the controller 100 detects a level difference between a portion shielded by the document and a portion not shielded by the document width sensor 13, and is conveyed by the pull-out roller 12. The size of the document in the width direction is determined and notified to the main body control unit 111. The length of the document in the conveyance direction is detected from the motor pulse by reading the leading edge and the trailing edge of the document with the butting sensor 11. When the document is transported from the resist section C to the turn section D by driving the pull-out roller 12 and the intermediate roller 14, the transport speed at the resist section C is set higher than the transport speed at the first reading transport section E. Thus, the processing time for sending the document to the first reading conveyance unit E is shortened.

  Control after the leading edge of the document is detected by the reading entrance sensor 15 differs depending on whether the operation mode is the non-stop mode or the stop mode.

  In the non-stop mode, before the leading edge of the document enters the nip portion of the reading entrance roller 16, the reading motor 103 is driven to rotate forward at the same time as deceleration is started in order to make the document conveying speed equal to the reading conveying speed. The reading inlet roller 16, the reading outlet roller 23, and the CIS outlet roller 27 are driven.

  Thereafter, the leading edge of the document is detected by the registration sensor 17 and the first surface (document surface) with respect to the main body control unit 111 at the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the reading position 20. A gate signal indicating an effective image area in the sub-scanning direction is transmitted until the trailing edge of the original passes through the reading position 20.

  On the other hand, in the stop mode, after the leading edge of the document is detected by the reading inlet sensor 15, a predetermined pulse count number is supplied so that a predetermined amount of deflection occurs after the document hits the nip portion of the reading inlet roller 16. After the paper motor 102 is driven, the document is stopped (resist stop), and a registration stop signal is transmitted to the main body control unit 111 via the I / F 107. That is, the position where the reading entrance roller 16 is provided is a stop position where the document stops.

  Subsequently, when a reading start signal is received from the main body control unit 111, the document whose registration has been stopped is transported at an increased speed to reach a predetermined transport speed until the leading edge reaches the reading position 20.

  Thereafter, the leading edge of the document is detected by the registration sensor 17, and at the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the reading position 20, the sub-scanning direction of the first surface with respect to the main body control unit 111. A gate signal indicating an effective image area is transmitted until the trailing edge of the document passes through the reading position 20.

  When the operation mode is the single-sided mode, the controller 100 conveys the document that has passed through the first reading conveyance unit E to the paper discharge unit G via the second reading unit 25. At this time, when the leading edge of the document is detected by the paper discharge sensor 24, the controller 100 drives the paper discharge motor 104 to rotate forward to rotate the paper discharge roller 28 counterclockwise. The controller 100 counts the pulses of the paper discharge motor 104 after the paper discharge sensor 24 detects the leading edge of the original, and the paper discharge motor 104 immediately before the trailing edge of the original comes out of the nip area of the paper discharge roller 28. The driving speed is reduced so that the document discharged onto the paper discharge tray 29 does not jump out.

  As described above, in the stop mode, the document is temporarily stopped by the reading entrance roller 16 when the leading edge is detected by the reading entrance sensor 15, and in the non-stop mode, the document is conveyed without being temporarily stopped.

  When the operation mode is the duplex mode, the controller 100 counts the pulses of the reading motor 103 after the leading edge of the document is detected by the paper discharge sensor 24, and the leading edge of the document reaches the second reading unit 25. At timing, a gate signal indicating an effective image area in the sub-scanning direction is output to the second reading unit 25. The gate signal is continuously output from the second reading unit 25 until the trailing edge of the document comes out.

  The surface of the second reading unit 25 is subjected to an antifouling coating process in order to prevent transfer of foreign matters on the glue attached to the document. The second reading roller 26 is disposed so as to face the second reading unit 25, and when the original passing through the second reading unit 25 is pressed against the second reading unit 25, the floating of the original in the second reading unit 25 is suppressed. At the same time, it also serves as a reference white part for acquiring shading data in the second reading unit 25 and performing shading correction. That is, the second reading roller 26 also serves as a white shading member.

  Hereafter, the characteristic part of this invention is demonstrated.

  As shown in FIG. 4, the document set on the basis of the end face is given a conveying force in the conveying direction (left direction in the figure) by the pull-out roller 12 and the intermediate roller 14, and reverse to the conveying direction by the reverse roller 10. A separation load in the direction of is given. Note that setting the document on the basis of the end surface means setting one end side in the width direction of the document to the reference position regardless of the size of the document.

  The reverse roller 10 applies a separation load by urging the document with a separation pressure. However, when the balance between the conveyance force applied to the document and the separation load in the document width direction is lost, skew (skew) occurs in the document. A moment is generated. In FIG. 4, the document is set with reference to the end face. However, the center reference, that is, the center in the width direction of the document is set at the reference position regardless of the size of the document, and the force applied to the document is symmetrical in the width direction. Even in such a case, if the user sets the document with the side fence slightly shifted, a moment that causes skew in the document is generated.

  As shown in FIG. 4, when the reverse roller 10 constituting the separating unit 401 is shifted to the back side (upper side in FIG. 4) from the center in the width direction of the document, the transport of the back side of the document is delayed. A skew, that is, a “previous skew” occurs. The separation unit 401 includes a reverse roller 10 and a paper feed belt 9 (see FIG. 6 and the like) that abuts on the reverse roller 10. The paper feed belt 9 rotates in the document conveyance direction, and the reverse roller The document 10 is separated by rotating 10 in the direction opposite to the document transport direction.

  Further, as shown in FIG. 5, when the reverse roller 10 constituting the separating unit 401 is shifted to the near side (lower side in FIG. 4) from the center in the width direction of the document, the transport of the near side of the document is performed. A skew in a delayed manner, that is, a “skew ahead” occurs.

  4 and 5, if the separation unit 401 releases the separation load on the document by the reverse roller 10, the left-right balance of the conveyance force generated on the document is maintained, and the conveyance of the document is stable. The sex will increase.

  Hereinafter, a method for releasing the separation load on the document by the reverse roller 10 will be described.

  As shown in FIG. 6, the reverse roller 10 is configured to be able to contact and separate from the paper feed belt 9. That is, as shown in FIGS. 6 and 7, the arm 10a that pivotally supports the reverse roller 10 is rotatable with respect to the fulcrum 10c, and the fulcrum 10c is centered by a biasing means such as a spring (not shown). It is pressurized in the clockwise direction.

  Then, as shown in FIG. 6, the reverse roller 10 is caused by the cam member 10q moving the arm 10a in the counterclockwise direction centering on the fulcrum 10c against the pressing force of the urging means (not shown). It is displaced to a predetermined position in contact with the paper feed belt 9. For this reason, when the reverse roller 10 is raised and in contact with the paper feed belt 9 and rotating in the direction opposite to the conveyance direction (clockwise), a separation load is applied to the document, and the reverse roller 10 is lowered. When the paper is separated from the paper feed belt 9, no separation load is applied to the original.

  As shown in FIG. 8, the reverse roller 10 is connected to the shaft 10b via a torque limiter 10d, and the direction from the drive gear (not shown) to the input gear 10f is the direction opposite to the paper feed and conveyance direction (clockwise in FIG. 6). This driving force is transmitted to the reverse roller 10 through the shaft 10b, the pin 10e press-fitted into the shaft 10b, and the torque limiter 10d. A drive gear (not shown) that meshes with the input gear 10f is disposed above the reverse roller 10 in FIG.

  The reverse roller 10 is configured to rotate in the direction of rotating around the paper feed belt 9 (counterclockwise in FIG. 6) by the action of the torque limiter 10d when a torque exceeding a predetermined value is applied to the shaft 10b.

  As shown in FIG. 9, when the leading edge of the document is guided to the separation unit 401 by the pickup roller 7 and separated by the separation unit 401, the reverse roller 10 has a predetermined winding angle with respect to the paper feed belt 9. It is fixed at a position where it can be restricted. Thus, the separation unit 401 functions as a separation mechanism to separate the document.

  Although the separation unit 401 includes the paper feed belt 9 and the reverse roller 10, the separation unit 401 may include a roller-shaped member corresponding to the paper supply belt 9 and the reverse roller 10. . That is, the member in contact with the reverse roller 10 may be a belt shape or a roller shape.

  Further, the separation unit 401 may be configured by a sheet feeding roller 309 and a separation pad 310 as in the separation unit 401a shown in FIGS. 15 (a) and 15 (b). 15A and 15B, the paper feed roller 309 rotates in the original transport direction (clockwise) similarly to the paper feed belt 9, and the separation pad 310 separates the original. 15A is controlled under the control of the controller 100 as shown in FIG. 15A, the original is sandwiched and pressed against the paper feed roller 309, and when the original is not separated, the original is shown in FIG. 15B. In this way, the paper is lowered and separated from the paper feed roller 309.

  As shown in FIG. 10, when the leading edge of the separated document passes through the separation sensor 303, the controller 100 assumes that the document separation operation is finished, rotates the cam member 10q to a predetermined position, and turns the reverse roller 10 on. The fulcrum 10c is rotated in a direction away from the paper feed belt 9 as a center. As a result, the reverse roller 10 is separated from the paper feed belt 9 and the separation function of the separation unit 401 is released.

  The paper feed belt drive roller 9a is provided to the drive shaft via a one-way clutch (not shown), and when the drive shaft is driven in the document feeding direction (clockwise in FIG. 6), the one-way clutch is locked and fed. When the paper belt drive roller 9a rotates, the driving force is transmitted to the paper feed belt 9, and the drive in the reverse direction (counterclockwise in FIG. 6) is applied from the drive shaft, the paper feed belt drive roller 9a rotates idle. ing.

  As a result, when the document is pulled in the document feeding direction (left direction in the figure), the paper feeding belt drive roller 9a is idled and rotated with the document. For this reason, even when the document is pulled by the downstream conveying roller (for example, the pull-out roller 12 or the intermediate roller 14), the reverse roller 10 is released, that is, the reverse roller 10 is separated from the paper feeding belt 9. If so, no separation load is generated on the document.

  A process in which the reverse roller 10 returns from the retracted position (down position) to the separation position (up position) again will be described. As a timing for returning the reverse roller 10 to the separation position, “rear end detection” that triggers that the “rear end” of the document after separation has passed a predetermined position, and “front end” of the document after separation is detected. There are two types of “tip detection” that triggers the passage of a predetermined position.

  In the case of “rear end detection”, as shown in FIG. 11, the “rear end” of the preceding document that has been separated is predetermined when the reverse roller 10 is retracted away from the paper feed belt 9. As shown in FIG. 12, the reverse roller 10 returns to the separation position (the raised position where it presses against the paper feed belt 9) and feeds the paper as a trigger. By contacting the belt 9, separation of the next document is started.

  Here, in order to reliably perform the separation operation, it is necessary that the reverse roller 10 surely returns to the separation position before the document is guided to the separation unit 401 by the pickup roller 7. For this reason, when the trailing edge of the preceding document passes a predetermined position (position of the abutment sensor 11), the reverse roller 10 starts to return to the separation position (waiting time, etc.). The time is set in consideration of the time required from the start of the return to the completion of the return.

  On the other hand, in the case of “leading edge detection”, as shown in FIG. 13, the leading edge of the preceding document after separation is in a predetermined position (position where the separation start sensor 302 is installed) with the reverse roller 10 retracted. When it reaches, as shown in FIG. 14, the reverse roller 10 returns to a predetermined separation position, and it becomes possible to start feeding the next document.

  In FIGS. 13 and 14, the trigger for returning the reverse roller 10 is that the leading edge of the document has reached the position of the separation start sensor 302 that is a predetermined position and is detected by the separation start sensor 302.

  In this case, as shown in FIG. 11 and FIG. 12, the detection of the trailing edge of the document at a predetermined position (position of the abutment sensor 11) after the document separation operation is finished, to the separation position of the reverse roller 10 as a trigger. It is possible to set the paper interval shorter than in the case of starting the return of. Here, the paper interval is the distance between the trailing edge of the preceding document and the leading edge of the succeeding document.

  A certain amount of time is required for the reverse roller 10 to return from the retracted position (position separated from the paper feeding belt 9 as shown in FIG. 13) to the separation position (position contacting the paper feeding belt 9 as shown in FIG. 14). Therefore, if it is attempted to shorten the paper gap to a certain level or less in order to ensure productivity, the reverse roller 10 may return to the separation position before the trailing edge of the document exits the separation unit 401 in the case of the leading edge detection configuration. As a result, a separation load may be applied to the document. Even in this case, the separation load is temporarily applied only to the trailing edge of the document as compared with the case where the separation roller is applied to the entire document while the reverse roller 10 is kept in pressure contact with the paper feeding belt 9. Since the effect is much smaller, the effect on skew etc. is sufficiently small.

  The document set on the document table 2 is detected by the document length detection sensors 30, 31, and 304, so that temporary size detection is performed, that is, the document size is adjusted before the document is conveyed. Although it is possible to detect, if all of the plurality of documents constituting the document bundle 1 are all the same size, the size of the first document is read, so that the more accurate based on the image data of the read document. It is possible to detect the document size and determine the size.

  By placing the separation start sensor 302 at an appropriate position and providing a waiting time until the reverse roller 10 is returned to the separation position after the leading edge of the document is detected by the separation start sensor 302 according to the document length, a plurality of The operation of returning the reverse roller 10 from the release position to the separation position is started at a timing that minimizes the interval between the originals so that the preparation can be surely separated before the next original reaches the separation position. It becomes possible to.

  Therefore, as shown in FIGS. 16 and 17, when the separation start sensor 302 is arranged on the upstream side in the document conveyance direction with respect to FIGS. 13 and 14, the separation start sensor 302 detects the leading edge of the document as shown in FIG. Then, after the waiting time corresponding to the document length elapses, the reverse roller 10 is returned to the separation position as shown in FIG.

  The timing for starting the displacement of the reverse roller 10 to the separation position is advanced by the time required for the reverse roller 10 to be displaced from the separation release position to the separation position, so that the next document is fed to the separation unit 401 before The reverse roller 10 can be reliably returned to the separation position.

  Next, the operation will be described.

  FIG. 18 shows a configuration in which, as shown in FIGS. 16 and 17, the reverse roller 10 is returned to the separation position after the waiting time corresponding to the length of the document has elapsed after the leading edge of the document is detected by the separation start sensor 302. The movement of each part when the first and second originals are called and the movement of the separation unit 401 when the third and subsequent originals are called are shown.

  In FIG. 18, the power is turned on (step S21), the start key is pressed (step S22), and the original is fed by the pickup roller 7 and separated by the separation unit 401 (step S23). It is determined whether or not the tip of the sensor has passed through the separation sensor 303 (step S24).

  If it is determined in step S24 that the leading edge of the document has passed the separation sensor 303, the reverse roller 10 is separated from the paper feed belt 9 to release the separation pressure and the pickup roller 7 is raised (step S25).

  Next, it is determined whether or not the original is the first original (step S26). If the original is the first original, the original is exposed and read while being read. Then, the size of the document is detected based on the read image data, and the size is determined (step S27).

  Next, it is determined whether or not the trailing edge of the document has passed through the separation sensor 303 (step S28). If the separation sensor 303 has been removed, the reverse roller 10 is returned to the separation position and brought into pressure contact with the paper feed belt 9 ( Step S29).

  On the other hand, if it is determined in step S26 that the document is not the first document, it is determined whether or not the leading edge of the document reaches the separation start sensor 302 (step S31). If it has reached, it waits for a pulse corresponding to the length of the document (step S32), and the reverse roller 10 is returned to the separation position and pressed against the paper feed belt 9 (step S33). Note that the document length used in step S32 is the size determined in step S27. If it is determined in step S31 that the leading edge of the document has not reached the separation start sensor 302, the process returns to step S25.

  After the reverse roller 10 is returned to the separation position and brought into pressure contact with the paper feed belt 9 by the process of step S29 or step S33, it is determined whether or not there is a next original (step S30), and the next original is present. In this case, the process returns to step S23, and if there is no next original, the processing in FIG.

  As can be seen from the flowchart of FIG. 18, the timing at which the second original is called differs from the timing at which the third and subsequent originals are called. That is, it is necessary that the size of the first document be determined as the timing for calling the second document, and that the trailing edge of the first document has left the separation unit 401. However, in order to determine the document size, it can be said that the trailing edge of the first document has left the separation unit 401. For this reason, the timing at which the second original is called is relatively later than the timing at which the third and subsequent originals are called. The timing at which the separation unit 401 returns from the released state (the state where the reverse roller 10 is separated from the paper feed belt 9) (the reverse roller 10 is pressed against the paper feed belt 9) is also 3 for the second original. The timing is later than when the first original is called.

  As described above, in the automatic document feeder 50 according to the present embodiment, the separation unit 401 contacts the one surface of the document and moves the document in the transport direction, and the other surface of the document. And a reverse roller 10 that regulates the movement of the document in the conveyance direction. Between the separation position where the reverse roller 10 is pressed against the paper feed belt 9 and the separation release position separated from the paper feed belt 9 After the arm 10a, the cam member 10q, and the leading edge of the document pass through the separation unit 401, the reverse roller 10 is displaced to the separation release position, and before the next document is fed to the separation unit 401, And a controller 100 for displacing the reverse roller 10 to a separation position.

  With this configuration, since the reverse roller 10 is moved to the separation release position after the original is separated and the original is conveyed, no separation load is applied to the original, so that the conveying force in the main scanning direction of the conveying means downstream thereof is balanced. Therefore, it is possible to suppress document skew and improve the conveyance stability.

  Further, the timing at which the reverse roller 10 returns from the separation release position to the separation position is controlled so that the next document is before being fed to the separation unit 401, thereby keeping the paper interval short and increasing the productivity. It becomes possible to keep.

  Therefore, the release and return of the separation function of the separation unit 401 are controlled at an appropriate timing to maintain high productivity by keeping the paper interval short and to reduce the cause of document skew to improve document conveyance stability and bend. It is possible to realize image reading without any problem.

  In addition, the automatic document feeder 50 according to the present embodiment includes a separation sensor 303 that is disposed near the downstream side of the separation unit 401 in the document conveyance direction and detects the passage of the edge of the document. Is triggered by the passage of the separation sensor 303 to drive the arm 10a and the cam member 10q to displace the reverse roller 10 to the separation release position.

  With this configuration, the release and return of the separation function of the separation unit 401 can be controlled at an appropriate timing.

  In addition, the automatic document feeder 50 according to the present embodiment includes a separation start sensor 302 that is arranged downstream of the separation sensor 303 in the document conveyance direction and detects the passage of the edge of the document. After the end passes the separation sensor 303, or after the leading edge of the document passes the separation start sensor 302, the arm 10a has an earlier timing by the time required for the reverse roller 10 to move from the separation release position to the separation position. The cam member 10q is driven to displace the reverse roller 10 to the separation position.

  With this configuration, the reverse roller 10 is moved to the separation position by driving the arm 10a and the cam member 10q at an earlier timing by the time required for the reverse roller 10 to be displaced from the separation release position to the separation position. The reverse roller 10 can be reliably displaced to the separation position before the document is fed to the separation unit 401.

(Second Embodiment)
19 to 21 are views for explaining an automatic document feeder according to a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  As a method of bringing the separation unit 401 into a released state, in addition to displacing the reverse roller 10, a method of controlling the rotation direction and torque of the reverse roller 10 as shown in FIGS. 19 and 20 can also be adopted. . That is, in FIG. 19, when the reverse roller 10 is rotated in the CCW direction (counterclockwise), the original is not subjected to a separation load, and therefore the reverse roller 10 is separated from the paper feed belt 9 in the first embodiment. It is possible to obtain the same effect as when

  In the present embodiment, as shown in FIG. 20, the reverse roller 10 is rotated by the driving force generated by the reverse roller driving motor 10j. Specifically, the driving force generated by the reverse roller drive motor 10j is transmitted to the reverse roller 10 through a gear 10g and a gear 10h for deceleration. The gears 10g and 10h are not indispensable requirements. For example, the reverse roller driving motor 10j may be directly connected to the reverse roller 10.

  The reverse roller drive motor 10j is a DC motor, for example, and the torque and the rotation direction are controlled by the applied current value.

  By driving the reverse roller drive motor 10j so that the rotation direction of the reverse roller 10 is the document conveyance direction (CCW direction), the separation load applied to the document in the separation unit 401 becomes zero. In the first embodiment, the reverse load is reversed. The same effect as when the roller 10 is separated from the paper feed belt 9 can be obtained.

  Further, the separation unit 401 performs a separation operation by driving the reverse roller drive motor 10j so that the rotation direction of the reverse roller 10 is opposite to the document conveyance direction (CW direction).

  Next, the operation will be described.

  FIG. 21 shows an outline of the rotation control of the reverse roller 10 of the separation unit 401 according to the present embodiment, and FIG. 22 shows the details of the rotation control of the reverse roller.

  In FIG. 21, the reverse roller 10 is driven in the CW direction by the reverse roller drive motor 10j (step S11), and it is determined whether or not the leading edge of the previous document has passed through the separation sensor 303 (step S12). If the separation sensor 303 has passed, the reverse roller 10 is driven in the CCW direction (step S13). If the leading edge of the document has not passed the separation sensor 303, the reverse roller 10 continues to be driven in the CW direction.

  Next, it is determined whether or not the leading edge of the previous document has passed the separation start sensor 302 (step S14). If the leading edge of the document has passed the separation start sensor 302, it is determined whether or not there is a next document. (Step S15) If the leading edge of the document does not pass through the separation start sensor 302, the reverse roller 10 continues to be driven in the CCW direction.

  If there is a next original in step S15, the process returns to step S11. If there is no next original, the process in FIG.

  In FIG. 22, the power is turned on (step S41), the start key is pressed (step S42), and the original is fed by the pickup roller 7 and separated by the separation unit 401 (step S43). It is determined whether or not the tip of the sensor has passed through the separation sensor 303 (step S44). In step S43, the reverse roller 10 of the separation unit 401 is driven in the CW direction.

  If it is determined in step S44 that the leading edge of the document has passed the separation sensor 303, the reverse roller 10 is driven in the CCW direction to cancel the document separation operation and raise the pickup roller 7 (step S45).

  Next, it is determined whether or not the original is the first original (step S46). If it is the first original, the original is exposed and read while being read, Based on the read image data, the size of the document is detected and the size is determined (step S47).

  Next, it is determined whether or not the trailing edge of the document has passed through the separation sensor 303 (step S48). If the separation sensor 303 has passed through, the reverse roller 10 is driven in the CW direction (step S49).

  On the other hand, if it is determined in step S46 that the document is not the first document, it is determined whether or not the leading edge of the document reaches the separation start sensor 302 (step S51). If it has reached, the reverse roller 10 is driven in the CCW direction only for the pulse corresponding to the length of the document (step S52), and then the reverse roller 10 is driven in the CW direction (step S53). Note that the document length used in step S52 is the size determined in step S47. If it is determined in step S51 that the leading edge of the document has not reached the separation start sensor 302, the process returns to step S45.

  After the reverse roller 10 is driven in the CW direction by the process of step S49 or step S53, it is determined whether or not there is a next original (step S50). If there is a next original, the process returns to step S43, and the next If there is no original, the processing in FIG. 22 is terminated.

  In this embodiment, while the reverse roller 10 is in pressure contact with the paper feed belt 9, the current applied to the reverse roller drive motor 10j is controlled to control the rotation direction of the reverse roller 10 as shown in FIGS. As a result, the responsiveness is better than when the reverse roller 10 is displaced by a mechanical method as in the first embodiment, and switching between shorter sheets is possible.

  Further, as described in detail with reference to FIG. 22, as in the first embodiment, the first original size is changed by changing the movement of the first and second sheets and the movement of the separation unit 401 after the third sheet. It becomes possible to shorten the gap between the papers more precisely by determining.

  As described above, in the automatic document feeder 50 according to the present embodiment, the separation unit 401 contacts the one surface of the document and moves the document in the transport direction, and the other surface of the document. And the reverse roller 10 that regulates the movement of the document in the conveyance direction. The rotation direction and torque of the reverse roller 10 are controlled, and the reverse roller 10 is moved after the leading edge of the document passes through the separation unit 401. And a controller 100 that rotates the reverse roller 10 in a direction opposite to the document conveyance direction before rotating the document in the document conveyance direction and before the next document is fed to the separation unit 401.

  With this configuration, by rotating the reverse roller 10 in the document conveyance direction after separating the document, the separation load is not applied to the document, so that the conveyance force in the main scanning direction of the conveyance unit downstream from the document is kept balanced. , Document skew and the like can be suppressed, and conveyance stability is improved.

  Further, the timing at which the rotation direction of the reverse roller 10 returns from the document conveying direction to the direction opposite to the document conveying direction is controlled so that it is before the next document is fed to the separation unit 401. Can be kept short and productivity can be kept high.

  Therefore, the release and return of the separation function of the separation unit 401 are controlled at an appropriate timing to maintain high productivity by keeping the paper interval short and to reduce the cause of document skew to improve document conveyance stability and bend. It is possible to realize image reading without any problem.

  In addition, the automatic document feeder 50 according to the present embodiment includes a separation sensor 303 that is disposed near the downstream side of the separation unit 401 in the document conveyance direction and detects the passage of the edge of the document. , The reverse roller 10 is rotated in the direction opposite to the document conveying direction with the passage of the separation sensor 303 as a trigger.

  With this configuration, the release and return of the separation function of the separation unit 401 can be controlled at an appropriate timing.

  In addition, the automatic document feeder 50 according to the present embodiment includes a separation start sensor 302 that is arranged downstream of the separation sensor 303 in the document conveyance direction and detects the passage of the edge of the document. Time required for the rotation direction of the reverse roller 10 to change from the direction opposite to the document conveying direction to the document conveying direction after the end has passed the separation sensor 303 or the leading edge of the document has passed the separation start sensor 302 The reverse roller 10 is rotated in a direction opposite to the document conveying direction at a timing earlier by the amount.

  With this configuration, the reverse roller 10 is rotated in the direction opposite to the document conveyance direction at a timing earlier by the time required for the rotation direction of the reverse roller 10 to change from the direction opposite to the document conveyance direction to the document conveyance direction. The rotation direction of the reverse roller 10 can be reliably changed to the direction opposite to the document conveyance direction before the next document is fed to the separation unit 401.

(Third embodiment)
Hereinafter, an outline of an image forming apparatus equipped with the automatic document feeder 50 will be described.

  As shown in FIG. 23, the image forming apparatus 70 includes an automatic document feeder 50 that transports a document, and an image forming apparatus main body 60 that reads a document and forms an image on a transfer sheet. The automatic document feeder 50 is provided so as to be openable and closable with respect to the image forming apparatus main body 60 via a hinge mechanism (not shown).

  An image reading unit 81 is provided in the image forming apparatus main body 60, and image information read by the image reading unit 81 is applied to the photosensitive drum 83 by the writing unit 82.

  The image reading unit 81 includes a light source 81a that illuminates a document on the contact glass 22 or the slit glass 21, a first mirror 81b, a second mirror 81c, a third mirror 81d that reflect light reflected from the document, and a first mirror 81d. A lens 81e that forms an image of the light reflected from the three mirrors 81d on the CCD image sensor 81f and a CCD image sensor 81f that converts the light imaged by the lens 81e into an electrical signal are provided.

  The light source 81a and the first mirror 81b are attached to a first traveling body (not shown), and the second mirror 81c and the third mirror 81d are attached to the second traveling body, and the first traveling body and the second traveling body. Moves along the contact glass 22 and the slit glass 21.

  When the first traveling body and the second traveling body read the document placed on the contact glass 22, the first traveling body and the second traveling body are moved in the left-right direction in the drawing below the contact glass 22 and read the document passing through the slit glass 21. Sometimes, it stops below the slit glass 21.

  The writing unit 82 irradiates a laser beam light-modulated according to the image information read by the image reading unit 81, and exposes the surface of the charged photosensitive drum 83 with the laser beam.

  Around the photosensitive drum 83, a developing device 86, a transfer belt 87, a cleaning device 88, a charging device and a charge eliminating device (not shown) that form an image forming unit together with the photosensitive drum 83 are provided. The charging device controls the corona discharge with a positive charge in the dark by a grid to charge the surface of the photosensitive drum to a constant potential.

  The writing unit 82 irradiates a laser diode containing image information onto the photosensitive drum 83 charged at this constant potential to remove negative charges on the photosensitive drum 83 to form an electrostatic latent image.

  The developing device 86 forms a visible image by attaching a negatively charged toner to the electrically removed portion on the photosensitive drum 83. A positive bias is applied to the transfer belt 87, and the transfer belt 87 transfers a negatively charged visible image onto a transfer sheet (paper) as a recording medium for conveyance.

  The cleaning device 88 is provided with a cleaning blade, and scrapes off the toner remaining on the photosensitive drum 83. The static eliminator turns on the internal LED to remove the residual charge on the photosensitive drum 83 and prepares to form a new image on the next transfer sheet.

  The transfer paper on which an image has been formed by the above process is conveyed to the fixing device 90 and the toner image is fixed by the fixing device 90.

  The image forming apparatus main body 60 is provided with storage cassettes 91 to 95 in which transfer papers of different sizes are stored, and the transfer paper stored in the storage cassettes 91 to 95 is called by calling rollers 91a to 95a. After being fed by the paper feed rollers 91b to 95b and the paper feed rollers 91b to 95b rotating in the transport direction and separated by the reverse rollers 91c to 95c rotating in the separation direction, the relay roller pair 96, The sheet is conveyed to a registration roller pair 98 through 97, and is timed by the registration roller pair 98 to be conveyed to a conveyance path between the photosensitive drum 83 and the transfer belt 87.

  As described above, the image forming apparatus 70 according to the present embodiment is equipped with the automatic document feeder 50 described above, so that release and return of the separating function of the separating unit are controlled at an appropriate timing, so It is possible to maintain high productivity by keeping it short, reduce the cause of document skew, improve document conveyance stability, and realize image reading without bending.

  As described above, the automatic document feeder and the image reading and forming apparatus according to the present invention control the release and return of the separating function of the separating unit at an appropriate timing, thereby keeping the sheet interval short and increasing the productivity. This has the effect of reducing the cause of the document skew and improving the document conveyance stability and realizing the image reading without bending, and automatically conveying one document from the document bundle. The present invention is useful as a document conveying device and an image forming apparatus including the automatic document conveying device.

1 Document bundle 2 Document table (document placement means)
3 movable document table 4 set filler 5 document set sensor 6 home position sensor 7 pickup roller (paper feeding means)
8 Proper feed position sensor 9 Feed belt (conveying member)
9a Feed belt drive roller 10 Reverse roller (regulating member)
10a Arm (regulating member displacement means)
10b shaft 10c fulcrum 10d torque limiter 10e pin 10f input gear 10g, 10h gear 10j reverse roller drive motor 10q cam member (regulating member displacement means)
11 Abutting sensor 12 Pull-out roller (conveying means)
13 Document width sensor 14 Intermediate roller (conveying means)
DESCRIPTION OF SYMBOLS 15 Reading entrance sensor 16 Reading entrance roller 17 Registration sensor 19 Reading roller 20 Reading position 21 Slit glass 22 Contact glass 23 Reading exit roller 24 Paper discharge sensor 25 2nd reading part 27 CIS exit roller 28 Paper discharge roller (paper discharge means)
29 Paper discharge tray 30, 31, 304 Document length detection sensor 50 Automatic document feeder 60 Image forming apparatus body 81 Image reading unit 81a Light source 81b First mirror 81d Third mirror 81e Lens 81f CCD image sensor 82 Writing unit 83 Photosensitive Body drum 86 Developing device 87 Transfer belt 88 Cleaning device 90 Fixing device 91-95 Storage cassette 91a-95a Roller 91b-95b Paper feed roller 91c-95c Reverse roller 96, 97 Relay roller pair 98 Register roller pair 100 Controller (control means, Control member control means)
101 Pickup Lifting Motor 102 Paper Feeding Motor 103 Reading Motor 104 Paper Discharge Motor 105 Bottom Plate Lifting Motor 107 I / F
DESCRIPTION OF SYMBOLS 108 Operation part 111 Main body control part 200 Light source part 201 Sensor chip 202 Amplification part 203 A / D conversion part 204 Image processing part 205 Frame memory 206 Output control circuit 207 I / F circuit 252 Inner guide member 261,262 Outer guide member 302 Separation Start sensor (second document detection means)
303 Separation sensor (first document detection means)
309 Paper feed roller 310 Separation pad 401 Separation unit (separation means)

JP 2004-352402 A JP 2005-263396 A JP-A-10-095552

Claims (7)

Document placing means for placing a bundle of documents composed of a plurality of documents;
A paper feeding means for feeding the topmost original from the original bundle placed on the original placing means;
Separating means for separating the document fed by the paper feeding means;
Conveying means for conveying the document separated by the separating means to a predetermined reading position;
In an automatic document feeder provided with a paper discharge means for discharging a document that has been read at the reading position,
The separating means includes a conveying member that contacts one surface of the document and moves the document in the conveying direction, and a regulating member that contacts the other surface of the document and restricts movement of the document in the conveying direction,
A restricting member displacing means for displacing the restricting member between a separation position in pressure contact with the conveying member and a separation releasing position separated from the conveying member;
After the leading edge of the original passes through the separating means, the restricting member displacing means is driven to displace the restricting member to the separation release position, and before the next original is fed to the separating means, An automatic document feeder comprising: control means for driving a regulating member displacing means to displace the regulating member to the separation position. A first document detecting unit disposed near the downstream side of the separating unit in the document transport direction and detecting passage of an end of the document;
The control means drives the restricting member displacing means to trigger the fact that the leading edge of the document has passed through the first document detecting means to displace the restricting member to the separation release position. 2. The automatic document feeder according to 1. A second document detection unit disposed downstream of the first document detection unit in the document transport direction to detect passage of an end of the document;
After the trailing edge of the document has passed through the first document detection means or after the leading edge of the document has passed through the second document detection means, the control means moves the regulating member from the separation release position to the separation position. 3. The automatic according to claim 1, wherein the restricting member displacing means is driven to displace the restricting member to the separation position at a timing earlier by a time required for displacement to the separation position. Document transport device. Document placing means for placing a bundle of documents composed of a plurality of documents;
A paper feeding means for feeding the topmost original from the original bundle placed on the original placing means;
Separating means for separating the document fed by the paper feeding means;
Conveying means for conveying the document separated by the separating means to a predetermined reading position;
In an automatic document feeder provided with a paper discharge means for discharging a document that has been read at the reading position,
The separating means includes a conveying member that contacts one surface of the document and moves the document in the conveying direction, and a regulating member that contacts the other surface of the document and restricts movement of the document in the conveying direction,
Restriction member control means for controlling the rotational direction and torque of the restriction member;
After the leading edge of the original passes through the separating means, the restricting member control means rotates the restricting member in the original conveying direction, and before the next original is fed to the separating means, the restricting member control means And an automatic document conveying device comprising: a control means for rotating the regulating member in a direction opposite to the document conveying direction. A first document detecting unit disposed near the downstream side of the separating unit in the document transport direction and detecting passage of an end of the document;
The control means causes the restriction member control means to rotate the restriction member in a direction opposite to the document conveyance direction, triggered by the fact that the leading edge of the document has passed through the first document detection means. 4. The automatic document feeder according to item 4. A second document detection unit disposed downstream of the first document detection unit in the document transport direction to detect passage of an end of the document;
After the trailing edge of the document has passed through the first document detection means or after the leading edge of the document has passed through the second document detection means, the control means determines that the rotation direction of the regulating member is the document conveyance direction. 5. The control device according to claim 4, wherein the restriction member is rotated in a direction opposite to the document conveyance direction by the restriction member control means at a timing earlier by a time required to change from the opposite direction to the document conveyance direction. The automatic document feeder according to claim 5.   An image forming apparatus comprising the automatic document feeder according to claim 1.

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