JP2020045199A - Sheet conveying device and image reading device - Google Patents

Abstract

To provide a sheet conveying device and an image reading device capable of effectively inhibiting collision noise without reducing productivity from being generated when a sheet bent by abutment collides with a conveyance guide.SOLUTION: A sheet conveying device for conveying a sheet Sc to a predetermined work position P1 includes a sheet feeding part B for conveying the sheet Sc in a feeding direction, an abutting roller 24 for causing a tip part thereof to abut against a nip part 24a to correct a skew, and conveying guides 41, 42 for restricting a bending direction of a sheet to be fed from the sheet feeding part B to the nip part 24a of the abutting roller 24 to a predetermined bending direction at least at a sheet feeding part B side; an abutting amount at the time when the sheet Sc is caused to abut against the nip part 24a of the abutting roller 24 is restricted to a value smaller than a predetermined feeding amount given by bringing the sheet to be fed at the sheet feeding part B side into contact with the conveying guide 41 when the sheet to be fed which is caused to abut against the abutting roller 24 is bent in the predetermined bending direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sheet conveying device and an image reading device, and more particularly to a sheet conveying device suitable for conveying a sheet to a predetermined work position such as an image reading position and an image reading device using the same.

  2. Description of the Related Art Conventionally, a sheet conveying device as a document conveying device or the like capable of separating a document sheet one by one from a cut sheet-shaped document bundle and conveying the document sheet to an image reading position is well known.

  In such a sheet conveying apparatus, generally, a separation sheet feeding mechanism that sequentially separates and feeds a document sheet from a document bundle on a document set table, and moves the separated and fed document to an image reading position in the main scanning direction. And a pair of registration rollers for sequentially conveying at a sub-scanning speed.

  Also, the separation sheet feeding mechanism is used so that the leading end of the document sheet separated and fed by the separation sheet feeding mechanism abuts the nip portion of the registration roller pair, and the document is curved between the separation sheet feeding mechanism and the registration roller pair. 2. Description of the Related Art There is known an apparatus in which conveyance control of a fed document is executed to correct (correct) the skew of the document.

  As this type of sheet conveying device and image reading device, for example, a thin elastic sheet is mounted on a document conveying surface of a guide plate facing a pickup roller, and a guide is formed so as to define a gap between the elastic sheet and the guide plate. By forming a concave portion in the plate, there is an apparatus that suppresses an impact sound when the pickup roller descends and prevents a loss time until the start of sheet feeding due to the rebound of the document sheet feeding means (for example, Patent Document 1). reference).

  In addition, by setting a substantial drop starting height when the feeding member such as the pickup roller descends toward the sheet bundle, the impact when the feeding member falls into the sheet bundle even if the sheet bundle is thin is set. In some cases, a noise or the like is reduced, or the lowering of the pickup roller is limited during the lowering, and a lowering limit operation is performed to reduce the lowering speed after the lowering (for example, see Patent Document 2).

  However, in a conventional sheet conveying apparatus and an image reading apparatus in which a thin elastic sheet is mounted on a document conveying surface, there is a concern that a document jam occurs due to wear, deterioration, breakage, etc. of the thin elastic sheet.

  Further, in the latter conventional sheet conveying device and image reading device in which the substantial drop start height of the feeding member is reduced or the descending speed is limited, the time required for descending becomes longer, so that the production time becomes longer. There is a problem that the property is reduced.

  The present invention has been made in order to solve such a conventional problem, and it is possible to reduce the generation of a collision sound or the like when a sheet bent by abutment collides with a conveyance guide without lowering productivity. It is an object of the present invention to provide a sheet conveying device that can be effectively suppressed and an image reading device using the same.

  A sheet conveying apparatus according to the present invention is a sheet conveying apparatus that conveys a cut sheet to a predetermined work position for achieving the above object, and a sheet feeding unit that conveys the sheet in a feeding direction; An abutting roller for abutting the leading end of the sheet fed from the sheet feeding unit to the nip portion to correct the skew of the sheet, and a feeding roller from the sheet feeding unit to the nip portion of the abutting roller. A conveyance guide that restricts the bending direction of the feeding sheet, and a hitting amount when hitting the sheet to the nip portion of the hitting roller is the feeding sheet hitting the hitting roller. When the sheet is bent in the bending direction, the feed sheet is limited to a value smaller than a feed amount that comes into contact with the conveyance guide.

  According to the present invention, by effectively suppressing the amount of bending of a sheet abutted against the abutting roller, it is possible to generate an abutting or a collision sound when the sheet bent by the abutting collides with the conveyance guide. And an image reading apparatus using the same.

FIG. 1 is a front sectional configuration diagram of an image forming apparatus with an image reading device using a sheet conveying device according to a first embodiment of the present invention. FIG. 1 is a front cross-sectional configuration diagram of a main part of an image forming apparatus with an image reading device using a sheet conveying device according to a first embodiment of the present invention. It is the elements on larger scale of the dotted line surrounding part II in FIG. FIG. 2 is a block diagram of a control system in the image forming apparatus according to the first embodiment of the present invention. 5 is a flowchart illustrating an example of a process from a document set to a sheet feeding before abutment in a series of processes from a call of a document to a stop of registration after the abutment in the image reading apparatus according to the first embodiment of the present invention. 6 is a flowchart exemplifying processing from the collision detection to the collision amount count and the start of conveyance after skew correction, following the processing in FIG. 5. FIG. 7 is a flowchart exemplifying processing during conveyance up to the stop of the resist, following the processing in FIG. 6. FIG. 4 is an enlarged partial plan view illustrating a case where skew of a document sheet can be detected by providing a plurality of abutting detection sensors in the image reading apparatus according to the first embodiment of the present invention so as to be separated in the sheet passing width direction. FIG. FIG. 9 is an explanatory diagram of a problem when carrying control of a comparative example is performed. FIG. 9 is a front cross-sectional configuration diagram of a main part of an image forming apparatus with an image reading device using a sheet conveying device according to a second embodiment of the present invention. FIG. 11 is a front cross-sectional configuration diagram of a main part of an image forming apparatus with an image reading device using a sheet conveying device according to a third embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(1st Embodiment)
FIGS. 1 to 4 show a schematic configuration of a main part of an image forming apparatus with an image reading device using a sheet conveying device according to a first embodiment of the present invention.

  An image forming apparatus 1 according to the present embodiment illustrated in FIG. 1 is a digital copier, and is a multifunction peripheral having both functions of an electrophotographic printer for forming an image and a scanner for conveying a sheet (document) and reading an image. . The image forming apparatus may further have a facsimile function, and the printer function may be an ink jet type.

  The image forming apparatus 1 is integrated with an image forming apparatus main body 1A, an image reading apparatus 10 located above the image forming apparatus main body 1A, and an openable / closable document pressing portion on the image reading apparatus 10, and cuts. A document transport device 20 (sheet transport device) for automatically transporting document sheets Sc (see FIG. 2) one by one from a sheet bundle SP of sheet-like documents to an image reading position is provided.

  Further, when a document image is read by the image reading device 10, the image forming apparatus main body 1A executes an image forming process based on image data obtained by digitizing the image document, and converts image data of the read image into a predetermined image data. It is possible to record (print) on a recording sheet or transfer and output a file of image data to a server via a network.

  As shown in FIG. 2, the image reading apparatus 10 includes a placed document image reading unit 101 having a flat bed contact glass 101 a on an upper side thereof, and a transport document image located on a side of the placed document image reading unit 101. The reading unit 102 includes a reading unit 102 and a slit glass 107 (DF contact glass) for reading a surface image, which is arranged parallel to a side of the flatbed contact glass 101a.

  As shown in FIG. 4, the image forming apparatus main body 1A includes an operation unit 108 integrally supported by the image reading device 10 so that various input operations and operation instructions can be performed, and a placed document image reading unit 101. And a built-in main body control unit 111 for controlling an image reading operation by the image reading unit 102 or the like.

  As shown in FIG. 1, an image forming unit 120 capable of forming one-color or multi-color images and a paper feeding unit for accommodating transfer papers S one by one are provided inside the image forming apparatus main body 1A. A transfer paper transport unit 140 that transports the transfer paper S from the paper feed unit 130 to the image forming unit 120 is provided.

  Inside the image forming apparatus main body 1A, a fixing unit 150 for heating and pressing the toner image formed by the image forming unit 120 and transferred to the transfer paper S to fix the transfer paper S is provided. A paper discharge unit 160 that discharges paper to any one of the paper trays 161, a post-processing device 170 that performs post-processing such as edge binding while raising and lowering a multi-stage paper discharge tray 171 for a plurality of discharged transfer papers S, and the like Is attached.

  Specifically, the image forming section 120 includes a rotating drum-shaped photoconductor 121, a charging section 122 for uniformly charging the surface thereof, and a writing output light generated based on image data from the image reading apparatus 10. There is provided an image exposure device 123 that irradiates the charged photoconductor 121 while deflecting it in a specific scanning direction to form an electrostatic latent image. In addition, the image forming unit 120 includes a developing unit 124 for visualizing the electrostatic latent image with toner, a transfer unit 125 for applying a bias voltage for transferring the toner image to the transfer sheet S, and a residual photoconductor 121. A charge removing unit 126 for removing charges, a remaining toner collecting unit 127, and the like are provided.

  The paper feeding section 130 is provided with paper trays 131 and 132 of two different sizes in the upper and lower stages with the bottom plate rising, so that a plurality of types of transfer paper S of different sizes can be fed from the paper trays 131 and 132. Has become.

  The transfer paper transport unit 140 has a plurality of roller pairs 141a, 141b, 141c, and transfers the transfer paper S from one of the paper feed trays 31, 132 to the image forming unit 120, the fixing unit 150, and the paper discharge unit. A first transport path 141 for transporting in the order of 160 is provided. Further, the transfer paper transport unit 140 has a plurality of roller pairs 142a, 142b, and 142c. In the double-sided printing mode, the transfer paper S on which one side has been fixed is turned upside down and fed again to the image forming unit 120. The second transport path 142 and a switching claw 143 for switching the transport path between the paper discharge unit 160 side and the second transport path 142 side are provided in parallel.

  In the image reading apparatus 10 arranged above the image forming apparatus main body 1A, the placed document image reading section 101 performs main scanning and sub scanning on the lower surface of the document sheet on the flat bed contact glass 101a (see FIG. 2). The function of a flatbed scanner that reads an original image by performing exposure scanning in the scanning direction is exhibited.

  On the other hand, the conveyed document image reading unit 102 shown in FIG. 2 has a function of a DF scanner for reading an image on the front side of the document sheet Sc being automatically conveyed. When the original sheet Sc is conveyed at a predetermined speed in the sub-scanning direction while passing through the reading position P1 (predetermined work position) on the slit glass 107, the conveyed original image reading section 102 slits the original image on the front surface. It has a surface scanning unit that performs main scanning from below in FIG.

  Hereinafter, the configuration of the document feeder 20 which is the first embodiment of the sheet feeder of the present invention will be described more specifically.

  As shown in a schematic front cross-sectional configuration diagram in FIG. 2, the document feeder 20 according to the present embodiment includes a document set unit A as a plurality of functional units arranged along the document feed path (sheet passing path). , A separation / feed unit B, a registration unit C, a turn unit D, a reading / conveying unit E (which may have a back surface reading / conveying unit F), a sheet discharging unit G, and a stacking unit H.

  The document setting section A is a document set on which a document sheet Sc which is a cut sheet-shaped document to be read (sheet) or a sheet bundle (hereinafter simply referred to as a document bundle) SP of a plurality of documents to be read is placed. The document to be read is set on the table with its surface facing upward, for example, the surface of the one-sided document on the side to be read (hereinafter simply referred to as the front surface).

  The separation feeding section B separates the uppermost original sheet Sc from the original bundle SP set in the original setting section A, and feeds the separated original sheet Sc to the entrance of the original conveying path 14. .

  The registration unit C performs a skew correction or the like by firstly abutting the original sheets Sc sequentially fed from the separation feeding unit B to align the original sheet Sc with a required transporting posture, and transfers the aligned original to the downstream side. And a function of pulling out and conveying.

  The turn part D has a reversing conveyance function of conveying the original sheet Sc pulled out and conveyed by the registration part C like a U-turn, and reversing the surface thereof downward in FIG.

  The reading / conveying section E conveys the folded original sheet Sc from the turn section D at a predetermined speed in the sub-scanning direction while passing through the reading position P1 on the slit glass 107.

  The back-side reading / conveying unit F is provided between the reading / conveying unit E and the sheet discharging unit G when a function of reading a double-sided image of a document is added. The original sheet Sc after reading the CCD image on the front side (the lower surface in FIG. 2) of the reading and conveying unit E is guided by the conveying guide 46, passes through the pair of paper discharge rollers 30, and lowers the switching unit downstream thereof. And is conveyed to the reversing roller side. The document sheet Sc conveyed to the reversing roller stops before its trailing end passes through the reversing roller, and reversely rotates to switch back the document sheet Sc. The document sheet Sc to be conveyed is conveyed to the registration roller 24 side by the pair of upper rollers of the discharge roller 30 and the roller above the same, with the switching unit being upward, and the back surface is read. Will be Note that the back side of the original sheet Sc conveyed at a predetermined speed in the sub-scanning direction when being conveyed downstream from the main scanning position of the front image while being guided by the conveyance guide 46 without providing such a double-side reversing mechanism. The main scanning may be performed by the CIS reading member for reading the back side image from the upper left side in FIG.

  The paper discharge unit G is configured to discharge the document sheet Sc, for which the document image has been read by the first take-up and transport unit E and the back surface reading and transporting unit F, to the stack unit H side.

  The stack portion H is configured to sequentially stack document sheets Sc sequentially discharged from the paper discharge portion G with the surface thereof facing downward, and the document sheets Sc or the bundle of documents SP is set on the document setting portion A. , And the original sheets Sc or the whole original bundle SP are stacked in a state where the original surface is upside down.

  More specifically, as shown in FIGS. 2 to 4, the document setting unit A vertically swings the document table 11 on which the document sheet Sc is set and the front portion of the document table 11 in the document conveying direction. A movable stop claw 12 movably provided, a swingable set detection filler 15 which comes into contact with the original sheet Sc when the original sheet Sc is set on the original table 11, and And a claw HP sensor 18 (see FIG. 4) for detecting that the stop claw 12 has swung to the lowermost home position. .

  The stop claw 12 swings to the highest position at the time of setting a document on the document table 11 and loads the leading end of a document sheet Sc or a document bundle SP (hereinafter, the set document is described as the document bundle SP). While being supported at a height corresponding to the number of sheets, the separating / feeding unit B can swing to the lowest position when the separating / feeding unit B is operated to open the inlet of the separating / feeding unit B.

  Although not shown in detail, the stop claw 12 is rotatably supported on the base end side by a frame-supported stop claw shaft 12a, and the upstream end of the transport guide 43 which becomes the lower guide for the paper feed entrance is also provided. It is rotatably mounted on the stop claw shaft 12a.

  When the original bundle SP is set on the original table 11, the set detecting filler 15 is rotated upward by the original bundle SP, and the original set sensor 16 swings the set detecting filler 15 upward. Sometimes, the set detection filler 15 is detected to indirectly detect that the document sheet Sc is set on the document table 11.

  When the document set state is detected by the set detection filler 15 and the document set sensor 16 in this manner, the detection information is transmitted to the main body control unit 111.

  A movable guide member (not shown) is provided on both sides of the document table 11 in the width direction orthogonal to the document conveyance direction. A document width sensor 33 and a pair of document length sensors 35 and 36 are provided in the vicinity of the document placing surface of the document table 11 as means for detecting a document size.

  As these size detecting sensors 33, 35, and 36, a reflective sensor that detects without contacting the original by optical means or a contact-type sensor that can detect even one original can be used. The sensors 33, 35, and 36 for size detection are arranged so as to determine whether the document is arranged vertically (longitudinal direction conveyance) or horizontally (short side conveyance).

  A plurality of conveyance guides 41, 42, 43, 44, 45, 46 for guiding the conveyed document sheet Sc along the document conveyance path 14 are provided on the document conveyance path from the separation feeding section B to the paper discharge section G. Is provided.

  Then, as shown in FIGS. 2 and 3, the separation feeding unit B calls the uppermost original from the plurality of transport guides 41 and 42 and the original bundle SP placed on the original table 11 in the paper feeding direction. A pick-up roller 21 that can be conveyed, and a separation sheet feeding mechanism 22 (sheet feeding unit) that separates the top one original sheet Sc from the other original sheets among the top originals called and conveyed by the pickup roller 21 ).

  The pickup roller 21 is driven by a call motor 71 shown in FIG. 4, and the separation paper feed mechanism 22 is driven by a paper feed motor 72 (separation paper feed drive source).

  Although a detailed support structure is not shown, the separation paper feed mechanism 22 is supported rotatably in the vertical direction by the rotation drive shaft 51a for inputting rotation from the paper feed motor 72 and the rotation drive shaft 51a on the base end side. A paper feed belt holder bracket (not shown), a movable belt support shaft 52a supported on the distal end side of the paper feed belt holder bracket, a driving pulley 51 and a movable belt support shaft fixed to a rotary drive shaft 51a. A driven pulley 52 rotatably supported by 52a, an endless feed belt 53 stretched between the pulleys 51 and 52, a contact angle and a contact pressure within a certain range with respect to the feed belt 53. And the reverse rollers 54 that come into contact with each other.

  The separation paper feed mechanism 22 has a nip portion 22a in which a paper feed belt 53 having a predetermined tension is wound around a surface of a reverse roller 54 at a predetermined pressure and within a predetermined angle range. When there is a subsequent document sheet that comes into contact with the reverse roller 54 in addition to the original document sheet Sc to be fed, the original sheet Sc to be fed is fed by the feed belt 53 and the lower subsequent document sheet is moved to the reverse roller 54. Is separated from the original sheet Sc to be fed.

  The nip angle θ in the nip portion 22a of the separation sheet feeding mechanism 22 can be adjusted by a belt tension adjusting mechanism (not shown).

  The registration section C is provided when an intermediate portion (no reference numeral) of the plurality of conveyance guides 41 and 43 in the document conveyance direction and the uppermost document sheet Sc separated and fed by the separation feeding mechanism 22 approaches the registration roller 24. A document abutting sensor 23 (document detecting means) for detecting the leading edge of the document sheet Sc at a predetermined position (sheet detecting position) in the transport direction, and the document sheet Sc detected by the document abutting sensor 23 against the register roller 24 And a registration roller 24 that conveys the original sheet Sc in the paper feeding direction on the condition that the predetermined abutment amount to be described later is reached, and a main scanning direction that is downstream of the registration roller 24 and that is orthogonal to the original conveyance direction. And a plurality of document width sensors 34 separated from each other.

  The registration roller 24 is composed of a pair of a roller 55 and a roller 56 disposed at an intermediate portion of the conveyance guides 41 and 43 in the document conveyance direction, and has a nip portion 24a that contacts each other with a predetermined nip pressure. The registration roller 24 can correct the skew of the document sheet Sc by aligning the leading end position of the document sheet Sc separately fed from the separation sheet feeding mechanism 22 with the upstream position in the conveyance direction of the nip portion 24a. Further, the original sheet Sc can be transported to the reading entrance roller 26 side.

  After the original sheet Sc reaches the predetermined abutting amount, the registration roller 24 reversely drives the one-way forward rotation paper feed motor 72 with respect to the rotation drive shaft 51a of the separation paper feed mechanism 22, for example. , And is driven to rotate in the paper feeding direction.

  The controller 70 detects the leading edge of the original sheet Sc by the original butting sensor 23 and the conveyance amount before and after the original sheet Sc abuts against the registration roller 24 due to the forward rotation of the paper feed motor 72 immediately after that. The drive control of the paper feeding motor 72 is executed so that the skew of the original sheet Sc can be corrected and the predetermined abutting amount can suppress the harsh noise caused by the abutting.

  The controller 70 further changes the abutting amount of the original sheet Sc against the registration roller 24 according to the original feeding speed (sheet feeding speed) from the separation sheet feeding mechanism 22 to the registration roller 24. When the feeding speed of the document sheet Sc is reduced to a predetermined value or less, the abutting amount is increased, and the feeding speed of the document sheet Sc is set to a high speed exceeding the predetermined value. Since the abutment amount is reduced when the collision is made, the generation of the collision sound at the time of the collision can be effectively suppressed.

  Note that if the document abutment sensor 23 detects the leading edge of the document sheet Sc and the speed is sufficiently lower than the transport speed in the paper feeding direction by the separation paper feeding mechanism 22, if the predetermined abutting amount can be reached, The roller 24 may be driven by an independent transport drive motor. Further, in this case, the transport driving of the registration roller 24 may be started early, and when a predetermined abutment amount is reached, the transport speed of the document sheet Sc by the registration roller 24 may be changed from a low speed to a high speed. .

  The document abutment sensor 23 can read the passage timing of the leading end and trailing end of the original sheet Sc, and the controller 70 counts the motor pulses during the passage timing of the leading end and trailing end, and thereby the conveying direction of the original sheet Sc is determined. The length of the can be detected.

  The turn portion D is configured to move the downstream curved portions of the transport guides 41 and 43 for guiding the original sheet Sc from the registration portion C to the reading transport portion E so that the original sheet Sc can be folded and transported, and the upstream curved portions of the downstream transport guides 44 and 45. It is comprised including.

  The reading and conveying unit E is arranged near the upstream curved portion of the conveying guides 44 and 45 and conveys the original sheet Sc to the reading and conveying unit E. The reading entrance roller 26 and the white sheet facing the slit glass 107 for reading the front surface image. A reference guide 47; and a reading exit roller 28 which is disposed near the facing portion of the conveyance guides 45 and 46 and carries out the document sheet Sc from the reading / conveying unit E at substantially the same speed as the reading entrance roller 26. I have.

  Here, the reading entrance roller 26 is constituted by a plurality of pairs of rollers for carrying the original sheet Sc conveyed from the registration rollers 24 into the curved portions on the side of the conveyance guides 44 and 45, and each roller pair is a roller of the original sheet Sc. A plurality of pairs of rollers are separated from each other in a rotation axis direction orthogonal to the document conveying direction, while being close to each other so as to contact both surfaces. The same applies to the reading exit roller 28, and the registration roller 24 and the paper discharge roller 30 can also be constituted by a plurality of pairs of rollers.

  The paper discharge unit G includes a downstream portion of the transport guide 45 and a transport guide 46 opposed thereto, a reading exit sensor 29 for detecting the original sheet Sc passing between the transport guides 45 and 46, and a reading exit sensor 29. After detecting the leading edge of the document, the document includes a discharge roller 30 that is driven to rotate so as to discharge the document sheet to the stack portion H, and a discharge tray 31 on which the discharged document is placed. I have.

  As shown in FIG. 4, the document feeder 20 includes a controller 70 for controlling the operation from the document setting section A to the paper discharge section G. The controller 70 includes at least the document set sensor 16 and the claw HP sensor. 18, a document abutment sensor 23, a reading entrance sensor 25, a reading exit sensor 29, a document width sensor 33, and document length sensors 35 and 36 are connected so as to be able to input signals.

  The document feeder 20 includes at least a call motor 71, a paper feed motor 72, a read motor 73, and a paper discharge motor 74 as actuators and the like that are driven and controlled by output signals from the controller 70.

  On the other hand, as described above, the image reading device 10 on which the document feeder 20 is mounted includes a main body control unit 111 that performs image formation control in cooperation with the controller 70 and an operation unit 108 that performs various input operations and operation instructions. And The controller 70 and the main body control unit 111 are signal-connected, and control signals, data, and the like are exchanged between them.

  Next, a basic operation from when a document is placed on the document table 11 until the document is discharged onto the discharge tray 31 and control by the controller 70 will be described.

  First, a document bundle SP is placed on a document table 11 including a stop claw 12 with its surface facing upward, and the width direction position of the document bundle SP, that is, the position in the direction perpendicular to the transport direction is shown. When the document is positioned by the side guide that is not set, the document is set.

  The document set state on the document table 11 is detected by the set detection filler 15 and the document set sensor 16, and the detection signal is taken into the controller 70 and also taken into the main body control unit 111. In addition, the size of the original of the original bundle SP on the original table 11 is detected by the size detection sensors 33, 35, and 36 provided on the surface of the original table 11 and taken into the controller 70, and also taken into the main body controller 111. It is.

  When the document set in the document setting section A is detected in this manner, the controller 70 controls the pickup roller so that the uppermost document sheet Sc of the document sheets Sc on the document table 11 contacts the pickup roller 21. 21 and the stop claw 12 are lowered.

  The pickup roller 21 is driven to move up and down by a call motor 71. When the pickup roller 21 descends, the pickup roller 21 comes into contact with the upper surface of the document sheet Sc on the document table 11 with a contact pressure corresponding to the play from the support bracket to the pickup roller 21 and its own weight. Therefore, even if the upper surface height of the document sheet Sc on the document table 11 changes, the contact pressure of the pickup roller 21 and the pickup drive rotation speed are maintained satisfactorily.

  Next, when the operation unit 108 is operated to specify either the double-sided mode or the single-sided mode and the reading key is pressed, a document feed signal is output from the main body control unit 111 to the controller 70.

  At this time, the controller 70 rotates the pickup roller 21 by rotating the sheet feeding motor 72 forward. The pick-up roller 21 that has started rotating picks up the uppermost document on the document table 11.

  The reverse roller 54 pushes the document in the paper feeding direction while the paper feeding belt 53 driven in the clockwise direction in FIG. 3 guides the document sheet Sc in the paper feeding direction by the normal rotation of the paper feeding motor 72. No operating state. Therefore, only the uppermost original sheet Sc picked up by the pickup roller 21 is separated from the lower original and fed in the sheet feeding direction.

  Here, in a state where the reverse roller 54 is in direct contact with the paper feed belt 53 or in a state where the reverse roller 54 is in pressure contact with a single original sheet Sc within a contact angle range, the reverse roller 54 is linked to the rotation of the paper feed belt 53, It rotates in a counterclockwise direction (paper feed direction) different from the original drive direction by the action of a torque limiter (not shown). However, when the uppermost original sheet Sc and an extra succeeding original on the lower side thereof are overlapped and picked up between the feed belt 53 and the reverse roller 54, the reverse roller 54 is moved to the highest position within the allowable torque range of the torque limiter. The document sheet Sc is rotated in the clockwise direction in FIG. 2 while separating an unnecessary succeeding document on the lower side from the document sheet Sc to prevent double feeding of the fed document sheet Sc.

  One document sheet Sc separated by the action of the sheet feeding belt 53 and the reverse roller 54 is sent out in the sheet feeding direction by the sheet feeding belt 53, and after the leading end sensor 23 detects the leading end thereof, , Against the registration roller 24.

  In this abutting, the separated original sheet Sc is transported a predetermined distance from the position detected by the original abutting sensor 23 in the paper feeding direction, so that the separated original sheet Sc is abutted and transported by a predetermined amount. The leading end portion is pressed against the registration roller 24 with the bending caused by the (abutting amount). Then, at the timing of the abutting state, the paper feeding motor 72 is stopped, and the driving of the paper feeding belt 53 is stopped.

  While the original sheet Sc is being fed and conveyed by the paper feed belt 53, the controller 70 raises the pickup roller 21 by the retrieving motor 71 via a cam mechanism and a pickup bracket (not shown) so as to separate from the upper surface of the original sheet Sc. The original sheet Sc is conveyed only by the conveying force of the paper feed belt 53. This corrects the skew of the original sheet Sc when the leading end of the original sheet Sc hits the nip portion of the registration roller 24.

  Next, the registration roller 24 is driven by the reverse rotation of the sheet feeding motor 72 so as to convey the skew-corrected document sheet Sc to the reading position P1 side (see FIG. 1). At this time, the registration roller 24 is driven, but the pickup roller 21 and the sheet feeding belt 53 that are driven when the sheet feeding motor 72 rotates forward are in a non-driving state.

  In addition, when the document is conveyed, when the document sheet Sc passes through the installation position of the plurality of document width sensors 34, among the plurality of documents adjacent in the document width direction, those which are shielded by the document sheet Sc and those which are not shielded are output. The controller 70 detects the level difference, determines the size of the conveyed document conveyed by the registration rollers 24 in the width direction, and notifies the main body control unit 111 of the size of the document.

  The length of the original sheet Sc in the transport direction is determined by reading the leading and trailing ends of the original sheet Sc by the original abutment sensor 23 and counting the drive pulses of the transport motor to detect the approximate length of the original sheet Sc. It is detected more accurately than the length sensors 35 and 36.

  When the original sheet Sc is transported from the registration section C to the turn section D by driving the registration roller 24, the controller 70 sets the transport speed in the registration section C to be higher than the transport speed in the reading transport section E. As a result, it is possible to reduce the processing time for sending the original to the reading and conveying unit E.

  As described above, the document transport device 20 transports the cut sheet document to the predetermined work position, and transports the document sheet Sc to the document reading position P1 while transferring the image of the document sheet Sc at the document reading position P1. A reading device, which is capable of abutting a separation feeding section B (sheet feeding section) for conveying a document sheet Sc in a feeding direction and a leading end portion of the document sheet Sc fed from the separation feeding section B. A registration roller 24 (butting roller) having a nip portion 24a and capable of correcting the skew of the original sheet Sc.

  In the document feeder 20, the upper surface of the transfer guide 42 that forms the document transfer surface of the document sheet Sc that is separated and fed from the separation feeding unit B is disposed on the axial center of the registration roller 24 as shown in FIG. The roller 56 is inclined downward with respect to the sheet insertion reference plane Hn orthogonal to the plane Vn, and the lower roller 56 of the registration roller 24 is on an extension of the inclination.

  Therefore, the leading end portion of the original sheet Sc fed from the separation feeding section B to the nip portion 24a of the registration roller 24 comes into contact with the lower roller 56 of the rollers 55 and 56 of the registration roller 24, and thereafter, the separation feeding is performed. Due to the difference between the paper feeding speed from the feeding unit B and the conveyance speed of the registration roller 24 (the registration roller 24 is stopped), the leading end of the document sheet Sc is pushed into the nip portion 24a and bent.

  That is, when the leading end of the document sheet Sc abuts on the nip portion 24a, the bending direction of the leading end side portion (also referred to as a fed document portion) of the separated document sheet Sc tends to be upwardly convex. As described above, since the leading end of the document sheet Sc comes into contact with the lower roller 56 and then strikes the nip portion 24a, it is possible to reduce the contact sound when the original sheet Sc strikes the lower roller 56.

  The amount of abutting of the original sheet Sc against the nip portion 24a of the registration roller 24 is such that the feeding sheet portion on the separation feeding portion B side abuts on the transport guide 41 as shown in FIG. At a small feed amount, the original transport distance (sheet transport distance) from the nip portion 22a of the separation paper feed mechanism 22 to the nip portion 24a of the registration roller 24 is equal to or less than a certain ratio.

  The abutting amount is controlled by the controller 70 so that the fed document portion on the side of the separation feeding section B does not abut the conveyance guide 41, and from the nip portion 22 a of the separation feeding mechanism 22 to the nip portion 24 a of the registration roller 24. Is less than 7% of the original transport distance. If it exceeds 7%, the fed document comes into contact with the transport guide 41 and a contact sound is generated.

  For example, when the document transport distance from the downstream end of the nip portion 22a to the upstream end of the nip portion 24a is 100 mm, and the distance from the document abutting sensor 23 to the upstream end of the nip portion 24a is 30 mm, the feed amount is , Which is 7 mm, which is 7%, added to the distance of 30 mm from the sensor 23. At this time, the feed amount is determined by the count value of the motor pulse. In the separation feeding mechanism 22, the document sheet Sc may slip and be conveyed. Therefore, a correction value is added to this count value. In this embodiment, the count value is set to a motor pulse count value of 40 mm obtained by adding about 10% of the feed amount. The correction value differs depending on the material and the nip length of the feed belt 53 and the reverse roller 54, the surface roughness and the inclination angle of the transport guide 42. As a result of the inventor's diligent efforts, an appropriate feed amount can be secured by setting the correction value to a count value obtained by adding 2% to 15%, preferably 5% to 10%. In addition, a mode may be provided in which a service person can change the count value, and an abutment amount changing means may be provided which can be changed by operation from the operation panel or data input.

  The controller 70 further controls the document to the nip portion 24a of the registration roller 24 according to the feeding speed of the document sheet Sc by the separation sheet feeding mechanism 22 of the separation feeding section B and the presence or absence of skew (skew) of the document sheet Sc. It may have a function as a butting amount changing means for increasing or decreasing the butting amount of the sheet Sc.

  Specifically, as shown in FIG. 8, the document abutment sensor 23 (abutment detection means) is configured with a higher detection accuracy by a plurality of document abutment sensors 23a and 23b, each of which can function as a document detection sensor. obtain. The document abutment sensors 23a and 23b are arranged so as to be separated from each other in a direction orthogonal to the width direction (paper passing width direction) of the document conveyance path 14 and to be located at the same position in the conveyance direction.

  Then, based on the leading edge detection information of each of the document abutting sensors 23a and 23b and the amount of deviation of the leading edge detection timing by the document abutting sensors 23a and 23b, the controller 70 adjusts the conveyance timing of the document sheet Sc and the inclination of the leading edge posture. By calculating the degree of the line, it is possible to determine whether or not the deviation amount is larger than a predetermined determination value and the leading edge of the document sheet Sc is skewed.

  More specifically, when the leading end posture of the original sheet Sc is skewed, the controller 70 determines the abutting amount of the original sheet Sc from the sensor 23a to be detected in advance as a specific value suitable for skew correction, for example, separation. The document transport distance from the nip portion 22a of the separation sheet feeding mechanism 22 of the feeding unit B to the nip portion 24a of the registration roller 24 is set to 4% or less.

  On the other hand, when the leading end posture of the document sheet Sc is not skewed, the abutting amount can be made smaller than 4% of the predetermined value. By using a plurality of document abutting sensors in this way, the amount of abutting can be reduced and the generation of sound can be further suppressed.

  Next, the operation will be described.

  FIG. 5 to FIG. 7 show processing procedures from the calling of the original after the original is placed to the stop of the registration roller 24 in the control executed by the control system of the image reading apparatus 10 and the original transporting apparatus 20 of the present embodiment. ing.

  First, the original bundle SP to be read is placed on the original table 11 with its original surface facing upward, and the original is set with the leading end of the original bundle SP abutting against the stop claw 12. Further, positioning in the direction orthogonal to the transport direction is performed by side fences (not shown) from both sides in the width direction of the document bundle SP. At this time, when the set detection filler 15 changes the angle from the broken line state shown in FIG. 2 to the solid line state, the document set sensor 16 (see FIGS. 2 and 4) detects the document set.

  Next, when a read key (not shown) is pressed from the operation unit 108 and a document feed signal is transmitted from the main body control unit 111 to the controller 70 serving as the ADF control unit, the document is set in the document setting state (step S11). In the case of YES), the retraction motor 71 is driven to rotate forward and the stop claw 12 is retracted until the retracting operation is detected by the pawl home position sensor 18 (steps S12 and S13).

  Next, the retrieving motor 71 is driven to rotate in the reverse direction until the pickup roller 21 reaches the pickup retrieving position for pressing the original bundle SP from above (the pickup roller 21 is lowered (steps S14 to S16)).

  Next, the document length sensors 35 and 36 provided on the document table 11 detect the approximate length of the document in the transport direction, and the document size is determined based on the combination with the detection result of the document width sensor 33 (step). S17).

  Next, the pickup roller 21 is rotated in the direction of feeding the uppermost document by the normal rotation of the paper feed motor 72 (step S18), and the upper document on the document table 11 is moved by the feed belt 53 and the reverse roller 54. The paper is fed to the configured separation paper feed mechanism 22. At this time, the paper feed belt 53 is driven in the paper feed direction by the normal rotation of the paper feed motor 72, and the reverse roller 54 does not feed.

  Next, when the leading edge of the document sheet Sc separated and fed by the separation sheet feeding mechanism 22 is detected by the abutment sensor 23 (YES in step S19), the leading edge of the document sheet Sc enters the nip portion 24a. With reference to the start timing or the entry timing in consideration of skew correction, transport speed error, and the like, the subsequent document transport amount is counted by the motor pulse of the paper feed motor 72 as the abutting amount (step S22).

  At this time, the pickup motor 71 is also driven to rotate in the reverse direction until the pickup roller 21 rises to the pickup retreat position away from the pickup recall position (steps S23-S24), and when the pickup roller 21 reaches the pickup retreat position. Then, the calling motor 71 is stopped (step S25).

  If the leading edge of the document sheet Sc separated and fed by the separation feeding mechanism 22 is not detected by the abutment sensor 23 for a certain period of time after the start of feeding, it is determined that the jam detection time is over (YES in step S20). Then, a predetermined jam process when the abutment has not been reached is executed (step S21).

  Next, the count value of the abutting amount (motor pulse) after the above-described abutting detection reaches a predetermined amount, for example, a predetermined number of pulses corresponding to the transport distance from the abutting sensor 23 to the registration roller 24 (YES in step S26). When a certain amount of bending is formed on the original sheet Sc by the registration rollers 24, the forward rotation of the sheet feeding motor 72 is stopped, and the original sheet Sc is stopped (step S27).

  At the time of abutting, the pickup roller 21 is retracted from the upper surface of the original by reversing the calling motor 71, and the original is sent only by the conveying force of the paper feeding belt 53, so that the leading end of the original is moved to the nip portion 24 a of the registration roller 24. The original sheet Sc that has entered and separated and fed can be corrected for skew.

  That is, the registration roller 24 has a skew correction function and is a roller for conveying the skew-corrected original sheet Sc to the reading entrance roller 26 after being separated, and is driven by the reverse rotation of the sheet feeding motor 72. When the sheet feeding motor 72 rotates in the reverse direction, the registration roller 24 is driven, but the pickup roller 21 and the sheet feeding belt 53 are not driven by the action of a one-way clutch (not shown).

  Next, it is determined whether or not a plurality of document width sensors 34 (see FIGS. 2 and 4) arranged in the depth direction are ON (YES in step S28), and the conveyance direction of the document sheet Sc conveyed by the registration rollers 24. Then, information on the document width orthogonal to is obtained (step S29).

  At this time, if a combination of the length information obtained from the detection results of the document length sensors 35 and 36 on the document table 11 and the document width information is not a so-called mixed mode (step S30), the main body is left as it is. The size information of the document bundle SP loaded on the document table 11 is transmitted to the control unit 111 (step S31).

  The exact length of the document in the transport direction is calculated by counting the number of motor drive pulses corresponding to the document transport distance while the leading edge and the trailing edge of the document sheet Sc are detected by the document abutting sensor 23, respectively. . Further, when the original sheet Sc is conveyed to the reading entrance roller 26 by the driving of the registration roller 24, the original conveying speed is set to be high and the processing time for sending the original sheet Sc to the reading section is shortened. In particular, in the case of the second and subsequent originals, productivity can be improved by shortening the sheet interval with the previous original by this high-speed conveyance.

  Next, when the leading edge of the document sheet Sc is detected by the reading entrance sensor 25 (step S32), a correction count is started to start the deceleration of the registration roller 24 before the leading edge of the document enters the reading entrance roller 26 (step S32). S35).

  Here, when the feed motor 72 is stopped so that the transport distance is longer by Y mm than the distance from the reading entrance sensor 25 to the reading entrance roller 26, the leading end of the document is placed in the nip portion of the stopped reading entrance roller 26. At the end, the document stops in a state where a certain amount of flexure is formed, and the skew generated when the document is conveyed by the registration roller 24 can be corrected.

  When the document is temporarily stopped (stop registration) at the nip portion of the reading entrance roller 26, a registration stop signal is transmitted to the main body control unit 111 (step S38).

  If the leading end of the document sheet Sc has not been detected by the reading entrance sensor 25 for a certain period of time after the start of conveyance by the registration rollers 24, it is determined that the jam detection time is over (YES in step S33). Is performed (step S34).

  When the main body control unit 111 receives the reading start signal, the document reading operation is started, the reading motor 73 is driven to rotate forward, and the reading entrance roller 26 and the reading exit roller 28 are driven at a transport speed corresponding to the reading magnification. You. When the leading edge of the document reaches the reading unit, a gate signal indicating the effective image area in the sub-scanning direction is sent to the main body control unit 111. The gate signal is normally sent until the trailing edge of the document passes through the reading unit. Then, the document that has passed through the reading unit is discharged to a discharge tray 31 by a discharge roller 30.

  The sheet conveying apparatus for conveying the original has been described above, but the suppression of the collision sound is also applicable to a sheet conveying apparatus as a sheet feeder of a main body cassette in a printer for forming an image or a manual sheet conveying apparatus.

  Next, the operation will be described.

  In the present embodiment configured as described above, the conveyance guides 41 and 42 that form the conveyance guide surfaces inclined with respect to the abutting nip portion 24 a are provided, and the deflection of the original sheet Sc abutted against the registration rollers 24 is performed. The amount is reduced to such an extent that it does not come into contact with the transport guide 41 on the side of the separation paper feed mechanism 22 where the transport path is widened in the direction perpendicular to the paper surface. Therefore, the sound generated when the original sheet Sc is bent or the bent shape is suddenly changed due to the collision, or the collision sound when the bent original sheet Sc collides with the transport guides 41 and 42. It is possible to provide a sheet conveying device capable of effectively suppressing the occurrence of the like, and an image reading device using the same.

  Further, in the present embodiment, the abutting amount of the document sheet Sc against the registration roller 24 is suppressed to 7% or less of the document conveyance distance from the nip portion 22a of the separation sheet feeding mechanism 22 to the nip portion 24a of the registration roller 24. Therefore, it is possible to effectively suppress the generation of a collision sound or the like when the bent original sheet Sc collides with the transport guides 41 and 42, while enabling the skew correction.

  Further, in the present embodiment, the controller 70 that controls the document conveyance changes the amount of abutting of the document sheet Sc against the registration roller 24 according to the document feeding speed from the separation sheet feeding mechanism 22 of the separation feeding unit B. It also has the function of the abutment amount changing means, which makes it possible to fine-tune the abutment amount, set a more optimal abutment amount, and effectively reduce the annoying noise when the originals abut. it can.

  In addition, in the present embodiment, the distance from the nip portion 24a of the registration roller 24 at the predetermined document detection position P2 where the leading edge portion of the document sheet Sc from the separation / sheet feeding mechanism 22 is detected by the document abutment sensor 23 is separated. Since the transport distance from the nip portion 22a of the paper feed mechanism 22 to the nip portion 24a of the registration roller 24 is set to 30% or less, the abutment timing of the document sheet Sc can be accurately detected by the document abutment sensor 23. There is little erroneous detection due to the bending of the original sheet Sc after the abutment. Further, it is possible to avoid the influence of the flutter of the original sheet Sc due to the conveyance slip or the like in the nip portion 22a of the separation sheet feeding mechanism 22, and to control the abutting amount reliably with less variation.

  Further, a document abutting sensor 23 serving as a document detecting means is constituted by a plurality of document abutting sensors 23a and 23b which are located between the separation sheet feeding mechanism 22 and the registration rollers 24 and are separated in a direction perpendicular to the feeding direction. Therefore, the controller 70 as the control means optimally varies the abutting amount in consideration of the skew of the original sheet Sc based on the original leading edge detection information of the plurality of original abutting sensors 23a and 23b. Can be controlled.

  As described above, in the present embodiment, by effectively suppressing the amount of bending of the original sheet Sc abutted against the registration roller 24, the abutting or the original sheet Sc is bent or its bent shape is suddenly changed. Sheet conveying apparatus and an image reading apparatus using the same, which can effectively suppress the sound generated by the above, the generation of a collision sound or the like when the bent original sheet Sc collides with any of the conveyance guides 41-43. Can be provided.

(Comparative example)
Incidentally, FIG. 9 illustrates the slippage during conveyance when the fed document portion abutted against the registration rollers 24 is bent in the predetermined bending direction during the conveyance control of the document sheet Sc ′ in the document conveyance device 20. However, the document feed distance from the nip portion 22a of the separation sheet feed mechanism 22 to the nip portion 24a of the registration roller 24 is high, for example, the document feed distance where the probability that the fed document portion on the separation feeding section B side will contact the transport guide 41 is high. 2 shows a comparative example in which the value is set to 20%.

  In this comparative example, the original sheet bent by the abutment hit one of the transport guides 41-43, and an unpleasant collision sound was generated.

(2nd Embodiment)
FIG. 10 is a front sectional configuration diagram of a main part of an image forming apparatus using a sheet conveying device according to a second embodiment of the present invention. Since each embodiment described below is similar to the first embodiment, the similarities to the first embodiment will be described using the corresponding reference numerals of the first embodiment. A description will be given of points similar to.

  As shown in FIG. 10, in the present embodiment, among the transport guides 41 and 42 that form the guide surfaces on both sides of the document sheet Sc, the upper transport guide 41 is provided with a section enlarging direction of the document transport path 14. A concave-shaped recessed portion 48 is formed which is recessed upward in the figure and opened downward.

  The recessed portion 48 has a wide range from the vicinity of the downstream end portion of the conveyance guide 42 to the separation sheet feeding mechanism 22 side in the document conveyance distance from the nip portion 22a of the separation sheet feeding mechanism 22 to the nip portion 24a of the registration roller 24. In addition, the cross section of the document conveying path 14 is a passage expanding space in which the cross section of the document sheet Sc is enlarged in a direction orthogonal to the sheet surface. The contact with the guide 41 can be effectively suppressed.

  The conveyance distance from the nip portion 24a of the registration roller 24 (abutting roller) to the original abutting sensor 23 serving as the original detecting means is set such that the original abutting sensor 23 is located near the downstream end of the concave portion 48. It is narrowed, and is 30% or less (more preferably, 15% or less) of the document conveyance distance from the paper feeding belt 53 to the registration roller 24.

  Also in the present embodiment, by effectively suppressing the amount of bending of the original sheet Sc abutted against the registration roller 24, a sound generated when the original sheet Sc bends or its bent shape suddenly changes, It is possible to provide a sheet conveying apparatus capable of effectively suppressing the generation of a collision sound or the like when the bent original sheet Sc collides with any of the conveying guides 41 to 43, and an image reading apparatus using the same. .

(Third embodiment)
FIG. 11 is a front cross-sectional configuration diagram of a main part of an image forming apparatus using the sheet conveying device according to the second embodiment of the present invention.

  As shown in FIG. 11, in the present embodiment, the bending of the original sheet Sc is performed on the lower surface of the low inclination angle portion on the side of the registration roller 24 in the transport guide 41 forming the guide surface on the main original surface side of the original sheet Sc. A cushioning member 61 is provided to reduce a collision sound when the document sheet Sc hits the transport guide 41 due to a change in shape or the like.

  Further, the distance from the registration roller 24 (abutting roller) to the document abutting sensor 23 is 30% or less of the document transport distance from the paper feeding belt 53 to the registration roller 24, and is within the area where the cushioning material 61 is attached. positioned.

  The material of the cushioning material 61 is, for example, urethane having a PET (polyethylene terephthalate) material sheet adhered to the surface, and the cushioning material 61 is between the separation feeding section B and the registration roller 32 and the lower surface of the transport guide 41 It is stuck along the guide surface on the side.

  Also in the present embodiment, by effectively suppressing the amount of bending of the original sheet Sc abutted against the registration roller 24, a sound generated when the original sheet Sc bends or its bent shape suddenly changes, It is possible to provide a sheet conveying apparatus capable of effectively suppressing the generation of a collision sound or the like when the bent original sheet Sc collides with any of the conveying guides 41 to 43, and an image reading apparatus using the same. .

  As described above, the present invention effectively suppresses the amount of bending of the sheet abutted against the abutting roller, thereby reducing the noise generated when the abutted sheet collides with the conveyance guide. It is possible to provide a sheet conveying device capable of effectively suppressing generation and an image reading device using the same, and convey a document sheet to an image reading position of the image reading device at a predetermined speed. The present invention is useful for a sheet conveying apparatus suitable for the above and an image reading apparatus using the same.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Image forming apparatus main body 10 Image reading apparatus 11 Document table 12 Stop claw 12a Stop claw shaft 14 Document conveyance path 15 Set detection filler 16 Document set sensor 18 Claw HP sensor 20 Document conveyance apparatus 21 Pickup roller 22 Separate paper feed Mechanism (Seat feeding unit)
22a Nip portion 23, 23a, 23b Document abutment sensor (document detection means, document detection sensor)
24 Registration roller (butting roller)
24a Nip part 25 Reading entrance sensor 26 Reading entrance roller 28 Reading exit roller 29 Exit sensor 30 Discharge roller 31 Discharge tray 32 Registration roller 33 Document width sensor 35, 36 Document length sensor 41 Transport guide (conveyance in predetermined bending direction side) guide)
42 Transport Guide (Transport Guide on Deflection Limit Side)
43 Transport Guide (Transport Guide Forming Introduction Guide Surface)
44, 45, 46 Transport guide 47 White reference guide 48 Depressed portion 51, 52 Pulley 51a Rotary drive shaft 52a Movable belt support shaft 53 Feed belt 54 Reverse roller 55, 56 Roller pair 61 Buffer material 70 Controller 71 Recall motor 72 Paper feed motor 73 Reading motor 74 Discharge motor 101 Placed document image reading unit (document image reading unit)
101a Flatbed contact glass 102 Conveyed document image reading unit (document image reading unit)
108 Operation unit 111 Main unit control unit 120 Image forming unit 130 Paper feed unit 140 Transfer paper transport unit 141 First transport path 142 Second transport path 143 Switching claw 150 Fixing unit 160 Paper discharge unit 161 Paper discharge tray 170 Post-processing device 171 Output tray A Document setting section B Separation feeding section (Sheet feeding section)
C Registration section D Turn section E Reading / conveying section F Back side reading / conveying section G Paper discharge section H Stack section Sc Document sheet (sheet)
SP Document bundle (sheet bundle)
P1 reading position (predetermined work position)
P2 Document detection position θ Nip angle

JP-A-2002-240963 JP 2001-220026 A

Claims (9)

A sheet transport device that transports the cut sheet to a predetermined work position,
A sheet feeding unit that conveys the sheet in a feeding direction,
An abutment roller for correcting the skew of the sheet by abutting against a nip portion after a leading end portion of the sheet fed from the sheet feeding unit abuts,
A conveyance guide that restricts a bending direction of a sheet fed from the sheet feeding unit to the nip portion of the abutment roller,
With
The abutting amount when the sheet is abutted against the nip portion of the abutting roller,
When the feed sheet abutted against the abutment roller is bent in the bending direction, the feed sheet is limited to a value smaller than a feed amount abutting on the transfer guide. apparatus.   2. The sheet according to claim 1, wherein an amount of abutting on the abutting roller is equal to or less than 7% of a sheet conveyance distance from a nip portion of the sheet feeding unit to a nip portion of the abutting roller. 3. Transport device.   The sheet conveying device according to claim 1, further comprising a contact amount changing unit configured to change the contact amount according to a sheet feeding speed of the sheet feeding unit. The apparatus further includes a sheet detection unit configured to detect a leading end portion of the sheet fed from the sheet feeding unit at a predetermined sheet detection position,
The distance from the nip portion of the abutment roller to the predetermined sheet detection position is 30% or less of the transport distance from the nip portion of the sheet feeding unit to the nip portion of the abutment roller. The sheet conveying device according to claim 1.   The sheet conveyance according to any one of claims 1 to 4, wherein the conveyance guide is provided with concave portions depressed toward the predetermined bending direction on guide surfaces on both sides of the sheet. apparatus.   A cushioning material is provided along the guide surface between the sheet feeding unit and the abutment roller, and on the guide surface on the predetermined bending direction side of both sides of the conveyance guide. The sheet conveying device according to any one of claims 1 to 5, wherein The sheet detection unit is configured to include a plurality of sheet detection sensors separated between the sheet feeding unit and the abutment roller and in a direction orthogonal to the feeding direction,
The sheet conveying apparatus according to any one of claims 1 to 6, further comprising control means for variably controlling the abutting amount based on sheet leading edge detection information of the plurality of sheet detecting sensors. . A sheet conveyance device according to any one of claims 1 to 7,
A document image reading unit configured to read an image of the sheet-shaped document conveyed to the predetermined work position. An image reading device according to claim 8,
An image forming apparatus main body that forms an output image based on image data of the document read by the image reading apparatus.

Images