JP7271883B2 - Sheet conveying device and image reading device - Google Patents

Description

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

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

In such a sheet conveying device, generally, there is provided a separation feeding mechanism for sequentially separating and feeding document sheets from a bundle of documents on a document set table, and feeding the separated and fed documents to an image reading position in the main scanning direction. A pair of registration rollers that sequentially convey the sheet at the sub-scanning speed are provided.

In addition, the separation and feeding mechanism causes the leading edge of the document sheet separated and fed by the separation and feeding mechanism to hit the nip portion of the registration roller pair and bend the document between the separation and feeding mechanism and the registration roller pair. It is known to correct (correct) the skew of the document by controlling the feeding of the document.

In a sheet conveying device and an image reading device of this kind, for example, a thin elastic sheet is attached to the document conveying surface of a guide plate facing a pickup roller, and a guide plate is provided so as to define a gap between the elastic sheet and the guide plate. By forming a recess in the plate, it is possible to suppress the impact noise when the pickup roller descends and to prevent the occurrence of lost time until the start of paper feeding due to rebounding of the document feeding means (for example, Patent Document 1). reference).

In addition, by setting a low drop start height when the feeding member such as the pickup roller descends toward the sheet bundle, even if the sheet bundle is thin, the impact when the feeding member falls on the sheet bundle is minimized. There is also a descent limiting operation that reduces noise and the like, or limits the descent of the pickup roller during the descent and reduces the descent speed after the limitation (see, for example, Patent Document 2).

However, in conventional sheet conveying devices and image reading devices in which a thin elastic sheet is attached to the document conveying surface, there is a concern that the thin elastic sheet may be worn, deteriorated, damaged, or otherwise jammed.

In addition, in the latter conventional sheet conveying device and image reading device in which the substantial fall start height of the feeding member is lowered or the descending speed is limited, the time required for descending becomes longer, which reduces production. There was a problem that the performance was lowered.

SUMMARY OF THE INVENTION The present invention has been made to solve such conventional problems. It is an object of the present invention to provide a sheet conveying device and an image reading device using the sheet conveying device that can effectively suppress the problem.

A sheet conveying device according to the present invention is a sheet conveying device for conveying a cut sheet to a predetermined working position in order to achieve the above object, comprising: a sheet feeding section for conveying the sheet in a feeding direction; a pair of upper and lower abutting rollers for correcting the skew of the sheet by abutting the leading edge of the sheet fed from the sheet feeding portion and then abutting the nip portion; and the abutting roller from the sheet feeding portion. an upper conveying guide that limits the bending direction of the upper side of the fed sheet up to the nip portion; a lower conveying guide that forms a conveying surface for the sheet that is separated and fed from the sheet feeding section; a sheet detection means for detecting the leading edge of the sheet fed from the unit at the sheet detection position, the lower conveyance guide inserting the sheet perpendicular to the axial center arrangement surface on the abutment roller side; The sheet is linearly inclined downward from the sheet feeding portion with respect to the reference plane, and the lower roller of the abutment rollers is on an extension of the downward inclination, and the sheet is moved from the sheet feeding portion to the nip portion. When the sheet is fed, the leading edge of the sheet comes into contact with the lower roller, and after the leading edge of the sheet is detected by the sheet detection means at the sheet detection position, the sheet is conveyed to the nip. The contact amount, which is the distance by which the sheet is conveyed until it is pushed against the contact roller and the conveying of the sheet feeding unit is stopped, is defined as the contact amount of the sheet, which is conveyed by contact with the contact roller. The feeding amount is limited to a value smaller than the feeding amount at which the feeding sheet comes into contact with the upper conveying guide when the feeding sheet is flexed.

According to the present invention, by effectively suppressing the amount of deflection of the sheet hit by the hit roller, a collision sound or the like is generated when the hit or the sheet bent by the hit collides with the conveying guide. It is possible to provide a sheet conveying device and an image reading device using the sheet conveying device that can effectively suppress .

1 is a front cross-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; FIG. FIG. 3 is a partially enlarged view of a portion II surrounded by a dotted line in FIG. 2; 3 is a block configuration diagram of a control system in the image forming apparatus according to the first embodiment of the invention; FIG. 5 is a flowchart illustrating processing from document setting to paper feeding before contact in a series of processes from document retrieval to registration stop after contact in the image reading apparatus according to the first embodiment of the present invention; FIG. 6 is a flow chart exemplifying the processing from the detection of abutment to the count of the amount of abutment and the start of conveyance after skew correction following the processing of FIG. 5 ; FIG. FIG. 7 is a flowchart exemplifying processing during transportation until registration stops following the processing in FIG. 6 ; FIG. FIG. 2 is an enlarged partial plan view of a main portion illustrating a case in which a skew of a document sheet can be detected by providing a plurality of abutment detection sensors spaced apart in the sheet passing width direction in the image reading apparatus according to the first embodiment of the present invention; It is a diagram. FIG. 10 is an explanatory diagram of a problem when carrying out transport control of a comparative example; FIG. 10 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;

Preferred embodiments of the present invention are described below with reference to the drawings.

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

The image forming apparatus 1 of the present embodiment shown in FIG. 1 is a digital copier, which is a multifunction machine having both the functions of an electrophotographic type printer for forming images and a scanner for conveying sheets (original documents) and reading images. . The image forming apparatus may further have a facsimile function, and may be of an inkjet type as a printer function.

This image forming apparatus 1 is integrated with an image forming apparatus main body 1A, an image reading device 10 positioned above the image forming apparatus main body 1A, and an open/close type document holding portion on the image reading device 10, and cuts the paper. A document conveying device 20 (sheet conveying device) is provided for automatically conveying document sheets Sc (see FIG. 2) one by one from a sheet bundle SP of sheet-like documents to an image reading position.

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 the image data obtained by digitizing the image document, and converts the image data of the read image to a predetermined value. Images can be recorded (printed) on recording paper, and image data files can be transferred and output to a server via a network.

As shown in FIG. 2, the image reading apparatus 10 includes a placed document image reading section 101 having a flatbed contact glass 101a on its upper side, and a conveyed document image reading section 101 positioned to the side of the placed document image reading section 101. It is provided with a reading unit 102 and a slit glass 107 (DF contact glass) for front surface image reading arranged in parallel to the 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 apparatus 10 so that various input operations and operation instructions can be performed, and a placed document image reading unit 101. and a built-in body control unit 111 for controlling the image reading operation by the conveyed document image reading unit 102 and the like.

As shown in FIG. 1, the image forming apparatus main body 1A includes an image forming section 120 capable of forming a single-color or multi-color image, and a paper feeding section for storing transfer sheets S one by one. 130 and a transfer paper conveying unit 140 for conveying the transfer paper S from the paper feeding unit 130 to the image forming unit 120 .

The image forming apparatus main body 1A further includes a fixing unit 150 for fixing the toner image formed by the image forming unit 120 and transferred to the transfer sheet S by heating and pressurizing it, and a plurality of ejectors for the transfer sheet S after fixing. A paper discharge unit 160 for discharging paper onto one of the paper trays 161, and a post-processing device 170 for performing post-processing such as edge binding while elevating the multistage paper discharge tray 171 for the plurality of discharged transfer sheets S. is attached.

Specifically, the image forming unit 120 includes a rotating drum-shaped photosensitive member 121 , a charging unit 122 that uniformly charges the surface of the photosensitive member 121 , and writing output light generated based on image data from the image reading device 10 . An image exposing device 123 is provided for forming an electrostatic latent image by irradiating the charged photoreceptor 121 while deflecting the light in a specific scanning direction. In addition, the image forming unit 120 includes a developing unit 124 that visualizes an electrostatic latent image with toner, a transfer unit 125 that applies a bias voltage for transferring the toner image onto the transfer paper S, and a residual photoreceptor 121 . A static elimination unit 126 that eliminates electric charges, a residual toner collection unit 127, and the like are provided.

The paper feed unit 130 is provided with paper feed trays 131 and 132 of different sizes in two stages, upper and lower, with a raised bottom plate. It's becoming

The transfer paper conveying unit 140 has a plurality of roller pairs 141a, 141b, and 141c, and transfers the transfer paper S from one of the paper feed trays 31 and 132 to the image forming unit 120, the fixing unit 150, and the paper discharging unit. A first transport path 141 is provided for transporting in the order of 160 . The transfer paper conveying unit 140 has a plurality of roller pairs 142a, 142b, and 142c. 2 conveying path 142 and a switching pawl 143 for switching the conveying path between the paper discharging section 160 side and the second conveying path 142 side.

In the image reading device 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 flatbed contact glass 101a (see FIG. 2). The function of a flatbed scanner is exhibited by exposing and scanning in the scanning direction to read the document image.

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

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

As shown in a schematic front cross-sectional view of FIG. 2, the document conveying device 20 of the present embodiment includes a document setting section A as a plurality of functional sections arranged along the document conveying path (paper passing path). .

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

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

The registration section C performs skew correction and the like by first abutting the document sheets Sc successively fed from the separation feeding section B, thereby aligning the document sheets Sc in a desired conveying posture. It has a function of drawing out and conveying.

The turning section D has a reversing conveying function of reversing and conveying the document sheet Sc pulled out and conveyed by the registration section C in a U-turn manner to reverse the surface downward in FIG.

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

The back side reading/conveying section F is provided between the reading/conveying section E and the paper discharge section G when the function of reading images on both sides of the document is added. The document sheet Sc after reading the CCD image on the front side (lower surface in FIG. 2) in the reading/conveying section E is guided by the conveying guide 46, passes through the pair of discharge rollers 30, and lowers the downstream switching section. , and is conveyed to the reversing roller side. The document sheet Sc conveyed to the reversing roller stops before the rear end passes through the reversing roller and rotates in the reverse direction to switch back the document sheet Sc. The document sheet Sc to be conveyed is conveyed to the side of the registration roller 24 by the pair of upper rollers of the discharge roller 30 and the rollers above it, and the reverse side is read. will be Without providing such a double-sided reversing mechanism, when the document sheet Sc is conveyed downstream from the main scanning position of the front surface image while being guided by the conveying guide 46, the back surface of the document sheet Sc is conveyed at a predetermined speed in the sub-scanning direction. 2 may be scanned obliquely from the upper left side in FIG.

The paper discharge section G discharges the original sheet Sc for which the original image reading in the first pick-up/conveyance section E and the back side reading/conveyance section F is completed to the stack section H side.

The stack unit H sequentially stacks the document sheets Sc discharged from the discharge unit G one by one with their surfaces facing downward. The document sheets Sc or the document bundle SP as a whole are stacked in the same page order as when the document sheets were stacked in such a manner that the direction of the document surface is turned upside down.

More specifically, as shown in FIGS. 2 to 4, the document setting section A includes a document table 11 on which the document sheet Sc is set, and a front side portion of the document table 11 in the document conveying direction. A movable stop pawl 12 provided movably, a set detection filler 15 capable of swinging in contact with the document sheet Sc when the document sheet Sc is set on the document table 11, and the set detection filler 15 on the upper side. and a pawl HP sensor 18 (see FIG. 4) for detecting that the stop pawl 12 has swung to the home position on the lowest side. .

The stop claw 12 swings to the highest position when the document is set on the document table 11, and stacks the leading edge of the document sheet Sc or the document bundle SP (hereinafter, it is assumed that the set document is the document bundle SP). While the sheets are supported at a height corresponding to the number of sheets, when the separating/feeding section B is operated, it can be swung to the lowest position to open the inlet portion of the separating/feeding section B.

Although not shown in detail, the stop pawl 12 is rotatably supported at its proximal end by a frame-supported stop pawl shaft 12a. It is rotatably attached to the stop pawl shaft 12a.

When the document stack SP is set on the document table 11, the set detection filler 15 is rotated upward by the document stack SP, and the document set sensor 16 swings the set detection filler 15 upward. When the document sheet Sc is set on the document table 11, it is indirectly detected by detecting the set detection filler 15 at times.

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 body control section 111 .

Movable guide members (not shown) are provided on both sides of the document table 11 in the width direction perpendicular to the document transport direction. A document width sensor 33 and a pair of document length sensors 35 and 36 are provided near the document placement surface of the document table 11 as means for detecting the document size.

As the sensors 33, 35, and 36 for size detection, a reflective sensor that detects the document without contacting the document by optical means or a contact sensor that can detect even a single document can be used. The size detection sensors 33, 35, and 36 are arranged so as to be able to determine whether the document is arranged vertically (conveyed in the longitudinal direction) or horizontally (conveyed in the lateral direction).

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

Then, as shown in FIGS. 2 and 3, the separating and feeding section B picks up the uppermost document from the stack of documents SP placed on the document table 11 with a plurality of transport guides 41 and 42 in the feeding direction. A pick-up roller 21 that can be transported, and a separating and feeding mechanism 22 (sheet feeding section) that separates the uppermost document sheet Sc from among the uppermost document sheets picked up and transported by the pickup roller 21 from the other document sheets. ) and

The pick-up roller 21 is driven by a pick-up motor 71 shown in FIG. 4, and the separating and feeding mechanism 22 is driven by a feeding motor 72 (separating and feeding drive source).

Although the detailed support structure is not shown, the separating and feeding mechanism 22 is supported by a rotary drive shaft 51a for inputting rotation from the feed motor 72 and by the rotary drive shaft 51a on the base end side so as to be vertically rotatable. a feed belt holder bracket (not shown), a movable belt support shaft 52a supported on the leading end side of the feed belt holder bracket, a driving pulley 51 fixed to a rotary drive shaft 51a, and a movable belt support shaft. A driven-side pulley 52 rotatably supported by 52a, an endless paper feed belt 53 stretched between both pulleys 51 and 52, and a contact angle and contact pressure within a certain range with respect to the paper feed belt 53. It is configured including a reverse roller 54 that contacts with .

The separating paper feeding mechanism 22 has a nip portion 22a in which a paper feeding belt 53 with a predetermined tension is wound around the surface of a reverse roller 54 within a predetermined pressure and a predetermined angle range. When there is a succeeding document sheet in contact with the reverse roller 54 in addition to the document sheet Sc targeted for paper, the document sheet Sc to be fed is fed by the feed belt 53 and the succeeding document sheet in the lower layer is fed by the reverse roller 54 . is separated from the document sheet Sc to be fed.

A nip angle θ at the nip portion 22a of the separating and feeding mechanism 22 can be adjusted by a belt tension adjusting mechanism (not shown).

The registration portion C includes an intermediate portion (no reference numeral) of the plurality of transport guides 41 and 43 in the document transport direction, and the uppermost document sheet Sc separated and fed by the separation feeding mechanism 22 when it approaches the registration roller 24 . A document contact sensor 23 (original detection means) that detects the leading edge of the document sheet Sc at a predetermined position (sheet detection position) in the conveying direction, and the document sheet Sc whose leading edge is detected by the document contact sensor 23 abuts against the registration roller 24 . and a registration roller 24 for conveying the original document sheet Sc in the paper feed direction and a main scanning direction perpendicular to the document conveyance direction on the downstream side of the registration roller 24 on the condition that a predetermined amount of contact, which will be described later, is reached. It includes a plurality of document width sensors 34 spaced apart from each other.

The registration rollers 24 are composed of a pair of rollers 55 and 56 arranged in the middle portion of the transport guides 41 and 43 in the document transport direction, and have a nip portion 24a that brings them into contact with each other with a predetermined nip pressure. The registration rollers 24 can correct the skew of the document sheet Sc by aligning the leading edge position of the document sheet Sc separated and fed from the separation feeding mechanism 22 to the upstream position of the nip portion 24a in the transport direction. Furthermore, the document sheet Sc can be conveyed to the reading entrance roller 26 side.

After the document sheet Sc reaches a predetermined contact amount, the registration rollers 24 reversely drive the one-way forward rotating paper feed motor 72 with respect to the rotary drive shaft 51a of the separation and paper feed mechanism 22, for example. , is driven to rotate in the sheet feeding direction.

The controller 70 detects the leading edge of the document sheet Sc by the document abutment sensor 23 and the transport amount before and after the document sheet Sc hits the registration roller 24 by the forward rotation of the paper feed motor 72 immediately after that. The drive control of the paper feed motor 72 is executed so that the skew of the document sheet Sc can be corrected and the amount of abutment can be suppressed to suppress the offensive noise caused by the abutment.

The controller 70 further changes the contact amount of the document sheet Sc against the registration rollers 24 in accordance with the document feeding speed (sheet feeding speed) from the separation and feeding mechanism 22 to the registration rollers 24. When the feeding speed of the document sheet Sc is decelerated below a predetermined value, the abutting amount is increased, while the feeding speed of the document sheet Sc is set to a high speed exceeding the predetermined value. Since the amount of impact is reduced when the impact is on, it is possible to effectively suppress the generation of impact noise when impacting.

It should be noted that if the transport speed in the paper feeding direction by the separation and feeding mechanism 22 is sufficiently lower than the feeding speed of the separation and feeding mechanism 22 after the leading edge of the document sheet Sc is detected by the document abutment sensor 23, and if the condition is such that a predetermined amount of abutment can be reached, the registration is performed. Rollers 24 may be driven by an independent transport drive motor. Further, in this case, the transport driving of the registration rollers 24 may be started early, and the transport speed of the document sheet Sc by the registration rollers 24 may be changed from low speed to high speed when a predetermined amount of contact is reached. .

The document abutting sensor 23 can read the passage timing of the leading edge and trailing edge of the document sheet Sc. length can be detected.

The turn portion D includes downstream curved portions of the transport guides 41 and 43 and upstream curved portions of the downstream transport guides 44 and 45 for guiding the document sheet Sc from the registration portion C to the reading transport portion E so as to be able to be folded back and transported. is composed of

The reading/conveying section E includes reading inlet rollers 26 arranged near the upstream curved portions of the conveying guides 44 and 45 to convey the document sheet Sc to the reading/conveying section E, and white rollers facing the slit glass 107 for reading the surface image. It includes a reference guide 47 and a reading outlet roller 28 which is arranged in the vicinity of the opposed portions of the conveying guides 45 and 46 and conveys the document sheet Sc out of the reading conveying section E at a speed substantially equal to that of the reading inlet roller 26. there is

Here, the reading inlet roller 26 is composed of a plurality of pairs of rollers for carrying the document sheet Sc conveyed from the registration rollers 24 into the curved portions on the side of the conveying guides 44 and 45. A plurality of pairs of rollers are close to each other so as to abut on both sides, and are spaced apart from each other in the rotation axis direction orthogonal to the document conveying direction. The read exit rollers 28 are similar, and the registration rollers 24 and the paper discharge rollers 30 can also be composed of multiple pairs of rollers.

The paper discharge section G includes a downstream portion of the transport guide 45 and a transport guide 46 facing the transport guide 46, a reading exit sensor 29 for detecting the document sheet Sc passing between the transport guides 45 and 46, and a reading exit sensor 29. It includes a paper discharge roller 30 that is rotationally driven to discharge the document sheet to the stack section H after the leading edge of the document is detected, and a paper discharge tray 31 on which the discharged document is placed. there is

As shown in FIG. 4, the document feeder 20 includes a controller 70 for controlling operations from the document set 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 conveying device 20 also includes at least a call motor 71 , a paper feed motor 72 , a read motor 73 and a paper discharge motor 74 as actuators driven and controlled by an output signal from the controller 70 .

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

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

First, the bundle of originals SP is placed on the original table 11 including the stop pawl 12 with its surface facing upward, and the position of the bundle of originals SP in the width direction, i. When it is positioned by the side guides that do not work, the document is set.

The set state of the document on the document table 11 is detected by the set detection filler 15 and the document set sensor 16 , and the detection signal is input to the controller 70 and also to the main body control section 111 . Further, the document size of the document bundle SP on the document table 11 is detected by the size detection sensors 33, 35, and 36 provided on the surface of the document table 11, and is fetched into the controller 70 and also into the main body control unit 111. be

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

The pickup roller 21 is driven up and down by a pick-up motor 71, and contacts 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 height of the upper surface 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 well.

Next, when either the double-sided mode or the single-sided mode is specified by operating the operation unit 108 and the read key is pressed, the main body control unit 111 outputs a document feed signal to the controller 70 .

At this time, the controller 70 rotates the pickup roller 21 by rotating the paper feed motor 72 forward. The pickup roller 21 that has started rotating picks up the top document on the document table 11 .

Further, the forward rotation of the paper feed motor 72 causes the paper feed belt 53, which is driven clockwise in FIG. not working. Therefore, only the uppermost document sheet Sc picked up by the pickup roller 21 is separated from the following document on the lower layer side and fed in the feeding direction.

Here, when the reverse roller 54 is in direct contact with the paper feed belt 53 or is in pressure contact with the paper feed belt 53 with one document sheet Sc sandwiched therebetween within the contact angle range, the reverse roller 54 is accompanied by the rotation of the paper feed belt 53. Due to the action of a torque limiter (not shown), it rotates in the counterclockwise direction (paper feeding direction), which is different from the original driving direction. However, when the uppermost document sheet Sc and the excess succeeding document below it are overlapped and picked up between the paper feed belt 53 and the reverse roller 54, the reverse roller 54 is the highest within the allowable torque range of the torque limiter. It rotates in the clockwise direction in FIG. 2 while separating an unnecessary succeeding document on the lower side from the document sheet Sc, thereby preventing double feeding of the fed document sheet Sc.

One document sheet Sc separated by the action of the paper feed belt 53 and the reverse roller 54 is sent out in the paper feed direction by the paper feed belt 53, and after the leading edge thereof is detected by the document abutment sensor 23, , but against the registration rollers 24 .

During this abutment, the separated and fed original sheet Sc is conveyed in the feeding direction by a predetermined distance from the position detected by the original abutment sensor 23, so that the separated original sheet Sc is abutted and conveyed by a predetermined amount. It is in a state of being pressed against the registration roller 24 at its leading end side portion, accompanied by bending due to (amount of contact). At the timing when the abutment state is reached, the paper feed motor 72 is stopped, and the drive of the paper feed 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 away from the upper surface of the original sheet Sc by the pickup motor 71 via a cam mechanism and a pickup bracket (not shown). , the document sheet Sc is conveyed only by the conveying force of the paper feed belt 53 . This corrects the skew of the document sheet Sc when the leading edge of the document sheet Sc hits the nip portion of the registration rollers 24 .

Next, the registration rollers 24 are driven by the reverse rotation of the paper feed 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 paper feed belt 53 that are driven when the paper feed motor 72 rotates forward are not driven.

Further, when the original document sheet Sc passes through the installation positions of the plurality of original document width sensors 34 when the original document sheet Sc is conveyed, output of the light shielded by the original document sheet Sc and the unshielded one among a plurality of adjacent ones in the document width direction is output. The controller 70 detects the level difference, determines the size in the width direction of the conveyed document conveyed by the registration rollers 24, and notifies the body control unit 111 of the document size.

In addition, the length of the document sheet Sc in the transport direction can be detected by reading the leading edge and the trailing edge of the document sheet Sc with the document abutment sensor 23 and by counting the driving pulses of the transport motor. It is detected more accurately than the length sensors 35 and 36.

When the document sheet Sc is transported from the registration section C to the turn section D by driving the registration rollers 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, the processing time for sending the document to the reading/conveying section E can be shortened.

In this manner, the document conveying device 20 is a sheet conveying device that conveys a cut sheet document to a predetermined working position, and conveys the document sheet Sc to the document reading position P1 while scanning the image of the document sheet Sc at the document reading position P1. The reading device includes a separation feeding section B (sheet feeding section) that conveys the document sheet Sc in the feeding direction, and a front end portion of the document sheet Sc fed from the separation feeding section B that can abut. A registration roller 24 (impact roller) having a nip portion 24a and capable of correcting the skew of the document sheet Sc is provided.

By the way, in the document conveying device 20, the upper surface of the conveying guide 42 forming the document conveying surface of the document sheet Sc separated and fed from the separation feeding portion B is arranged at the axial center of the registration roller 24 side as shown in FIG. It is inclined downward with respect to the sheet insertion reference plane Hn perpendicular to the plane Vn, and the roller 56 below the registration roller 24 is on the extension of the inclination.

Therefore, the leading end portion of the document sheet Sc fed from the separation feeding portion B to the nip portion 24a of the registration roller 24 contacts the roller 56 on the lower side among the rollers 55 and 56 of the registration roller 24, and then separates and feeds. The leading edge of the original sheet Sc is pushed into the nip portion 24a and bent due to the difference between the feeding speed from the feeding portion B and the conveying speed of the registration rollers 24 (the registration rollers 24 are stopped).

That is, when the leading edge of the document sheet Sc abuts against the nip portion 24a, the deflection direction of the leading edge side portion of the separated document sheet Sc (also referred to as the fed document portion) tends to flex upward. In this manner, the leading edge of the document sheet Sc contacts the roller 56 on the lower side and then hits the nip portion 24a.

As shown in FIG. 3, the contact amount of the document sheet Sc against the nip portion 24a of the registration roller 24 is such that the portion of the sheet to be fed on the side of the separating/feeding portion B comes into contact with the conveying guide 41. It is less than a fixed ratio of the document conveying distance (sheet conveying distance) from the nip portion 22a of the separation feeding mechanism 22 to the nip portion 24a of the resist roller 24.

The amount of contact is controlled by the controller 70 so that the portion of the document to be fed on the side of the separating and feeding section B does not come into contact with the conveying guide 41. The value is 7% or less of the document conveying distance of . If it exceeds 7%, the fed original comes into contact with the conveying guide 41 and a contact noise is generated.

For example, when the document conveying 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 contact sensor 23 to the upstream end of the nip portion 24a is 30 mm, the feed amount is , the distance from the sensor 23 is 30 mm, and 7 mm, which is 7%, is added to 37 mm. At this time, the feed amount is determined by the motor pulse count value. In the separating and 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 motor pulse count value is set to 40 mm by adding about 10% of the feed amount. This correction value varies depending on the material and nip length of the paper feed belt 53 and the reverse roller 54 and the surface roughness and inclination angle of the transport guide 42 . As a result of the inventor's diligent efforts, an appropriate feed amount could be ensured by setting the correction value to a count value obtained by adding 2% to 15%, preferably 5% to 10%. Further, the count value may be changed by a service person, and may be provided with contact amount changing means that can be changed by operation from the operation panel or data input.

The controller 70 further controls the feeding speed of the document sheet Sc by the separation feeding mechanism 22 of the separation feeding section B and the presence or absence of the skew of the document sheet Sc. It may also have a function as a bumping amount changing means for increasing or decreasing the bumping amount of the sheet Sc.

More specifically, as shown in FIG. 8, the document abutment sensor 23 (abutment detection means) is composed of a plurality of document abutment sensors 23a and 23b each functioning as a document detection sensor with higher detection accuracy. obtain. These document abutting sensors 23a and 23b are spaced apart in a direction perpendicular to the width direction of the document transport path 14 (the width direction of the sheet passing) and are positioned at the same position in the transport direction.

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

More specifically, when the orientation of the leading edge of the document sheet Sc is skewed, the controller 70 sets the amount of contact of the document sheet Sc from the sensor 23a for preceding detection to a specific value suitable for skew correction, e.g. The document transport distance from the nip portion 22a of the separating and feeding mechanism 22 of the feeding section B to the nip portion 24a of the registration roller 24 is 4% or less.

On the other hand, when the orientation of the leading edge of the document sheet Sc is not skewed, the amount of contact can be less than 4% of the predetermined value. By using a plurality of document abutment sensors in this way, the amount of abutment can be reduced and the generation of sound can be further suppressed.

Next, operation will be described.

FIGS. 5 to 7 show the processing procedure from calling the document after the document is placed to stopping the registration rollers 24 among the controls executed by the control system of the image reading apparatus 10 and the document conveying apparatus 20 of the present embodiment. ing.

First, a bundle of originals SP to be read is placed on the original table 11 with the surface of the originals facing upward. Positioning in a direction perpendicular 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, by changing the angle of the set detection filler 15 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 body control unit 111 to the controller 70, which is the ADF control unit, on condition that the document is set (step S11). If YES), the call motor 71 is driven forward to retract the stop claw 12 until the retraction operation is detected by the claw home position sensor 18 (steps S12 and S13).

Next, the pickup motor 71 is reversely driven (the pickup roller 21 is lowered (steps S14-S16) until the pickup roller 21 reaches the pickup call position where it presses the document bundle SP from above.

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

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

Next, when the leading edge of the document sheet Sc separated and fed by the separation 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. Based on the start timing, or on the basis of the approach timing in consideration of skew correction, conveyance speed error, etc., the subsequent document conveyance amount is counted by motor pulses of the paper feed motor 72 as the amount of contact (step S22).

At the same time, the pickup motor 71 is reversely driven (steps S23-S24) until the pickup roller 21 rises from the pickup calling position to the pickup retracting position, and when the pickup roller 21 reaches the pickup retracting position. , the call 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 abutting sensor 23 for a certain period of time after the start of feeding, it is determined that the jam detection time has expired (YES in step S20). , a predetermined jam processing when the contact is not reached is executed (step S21).

Next, the count value of the amount of contact (motor pulse) after the detection of contact reaches a predetermined amount, for example, a predetermined number of pulses corresponding to the conveying distance from the contact sensor 23 to the registration roller 24 (YES in step S26), When the document sheet Sc is flexed to a certain extent by the registration rollers 24, the feeding motor 72 is stopped to rotate forward and the document sheet Sc stops (step S27).

At the time of abutment, the pickup roller 21 is retracted from the upper surface of the document by rotating the pick-up motor 71 in reverse, and the document is fed only by the conveying force of the paper feed belt 53, so that the leading edge of the document reaches the nip portion 24a of the registration roller 24. It is in a state in which the skew of the document sheet Sc that has occurred during separation and feeding can be corrected.

That is, the registration rollers 24 have a skew correction function and are rollers for conveying the skew-corrected document sheet Sc to the reading entrance roller 26 after separation, and are driven by the reverse rotation of the paper feed motor 72 . When the paper feed motor 72 is reversed, the registration rollers 24 are driven, but the pick-up roller 21 and the paper feed belt 53 are not driven due to 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). Information on the width of the document perpendicular to is obtained (step S29).

At this time, if the combination of the length information obtained from the detection result of the document length sensors 35 and 36 on the document table 11 and the document width information is not a so-called mixed loading mode (step S30), the main body Size information of the document stack SP stacked 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 driving pulses corresponding to the document transport distance while the document abutment sensor 23 detects the leading edge and the trailing edge of the document sheet Sc. . Further, when the document sheet Sc is conveyed to the reading entrance roller 26 by the driving of the registration rollers 24, the document conveying speed is set to a high speed to shorten the processing time for sending the document sheet Sc to the reading section. In particular, for the second and subsequent originals, this high-speed transport shortens the distance between the originals and the preceding original, thereby improving productivity.

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 decelerating the registration rollers 24 before the leading edge of the document enters the reading entrance roller 26 (step S32). S35).

Here, when the paper feeding motor 72 is stopped so that the conveying distance becomes longer by Y mm than the distance from the reading entrance sensor 25 to the reading entrance roller 26, the leading edge of the document is placed in the nip portion of the stopped reading entrance roller 26. The document comes to a stop in a state where it strikes and forms a certain amount of flexure, and the skew that occurs when the document is conveyed by the registration rollers 24 can be corrected.

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

If a predetermined time or more has passed without the leading edge of the document sheet Sc being detected by the reading entrance sensor 25 after the start of transportation by the registration rollers 24, it is determined that the jam detection time has expired (YES in step S33), and the leading edge detection has not been reached. is executed (step S34).

Further, when the 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 conveying speed corresponding to the reading magnification. be. At the timing when the leading edge of the document reaches the reading section, a gate signal indicating the effective image area in the sub-scanning direction is sent to the body control section 111, and the gate signal is normally sent until the trailing edge of the document passes through the reading section. After passing through the reading unit, the document is discharged to a paper discharge tray 31 by a paper discharge roller 30 .

Although the sheet conveying device that conveys the document has been described in this way, the suppression of collision noise can also be applied to a sheet conveying device serving as a main body cassette feeding device or a manual sheet conveying device in a printer that forms an image.

Next, the action will be described.

In the present embodiment configured as described above, the transport guides 41 and 42 forming transport guide surfaces inclined with respect to the abutment nip portion 24a are provided, and the deflection of the document sheet Sc abutted against the registration roller 24 is prevented. 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 separating and feeding mechanism 22 where the transport path is widened in the direction perpendicular to the paper surface. Therefore, the sound generated by the abutment, the bending of the document sheet Sc due to the abutment, or the sudden change in the bent shape, and the collision sound when the bent original sheet Sc collides with the conveying guides 41 and 42. It is possible to provide a sheet conveying device and an image reading device using the same that can effectively suppress the occurrence of such problems.

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

Further, in the present embodiment, the controller 70 that controls document transport changes the amount of contact of the document sheet Sc against the registration rollers 24 according to the document feeding speed from the separation feeding mechanism 22 of the separation feeding section B. Since it also has a function of abutting amount changing means, it is possible to finely adjust the abutting amount to set a more optimum abutting amount and to effectively reduce harsh noise when the document is abutted. can.

In addition, in the present embodiment, the distance from the nip portion 24a of the registration rollers 24 to the predetermined document detection position P2 at which the document abutment sensor 23 detects the leading edge of the document sheet Sc from the separation feeding mechanism 22 is the separation Since it is set to 30% or less of the conveying distance from the nip portion 22a of the paper feeding mechanism 22 to the nip portion 24a of the registration roller 24, the contact timing of the document sheet Sc can be accurately detected by the document contact sensor 23. There are few erroneous detections due to bending of the document sheet Sc after being hit. In addition, it is possible to avoid the influence of fluttering of the document sheet Sc due to transport slippage or the like at the nip portion 22a of the separating and feeding mechanism 22, and it is possible to reliably control the amount of abutment while suppressing variations.

A document abutment sensor 23, which is a document detection means, is composed of a plurality of document abutment sensors 23a and 23b spaced apart in a direction perpendicular to the feeding direction between the separation feeding mechanism 22 and the registration roller 24. Therefore, the controller 70, which is control means, can optimally vary the abutment amount based on the document leading edge detection information from the plurality of document abutment sensors 23a and 23b, taking into consideration the skew of the document sheet Sc. can be controlled.

As described above, in the present embodiment, by effectively suppressing the amount of deflection of the document sheet Sc hit against the registration rollers 24, the contact and the document sheet Sc can be bent or the bent shape can be abruptly changed. A sheet conveying device and an image reading device using the sheet conveying device capable of effectively suppressing the sound generated when the document sheet Sc collides with any one of the conveying guides 41 to 43. can be provided.

(Comparative example)
Incidentally, in FIG. 9, in the document conveying device 20, when the portion of the document to be fed that abuts against the registration roller 24 is bent in a predetermined bending direction during the control of the conveyance of the document sheet Sc', slipping during conveyance and the like are taken into consideration. Even if there is a high probability that the portion of the document to be fed on the side of the separating and feeding section B will come into contact with the conveying guide 41, the predetermined feeding amount, for example, the document conveying distance from the nip portion 22a of the separating and feeding mechanism 22 to the nip portion 24a of the registration roller 24 20% of the comparative example.

In this comparative example, the original sheet bent due to the abutment hit one of the conveying guides 41 to 43, generating an offensive collision sound.

(Second embodiment)
FIG. 10 is a front cross-sectional configuration diagram of a main part of an image forming apparatus using a sheet conveying device according to the second embodiment of the present invention. Since each embodiment described below is similar to the first embodiment, the same reference numerals as in the first embodiment are used for points similar to the first embodiment. Similar points will be explained.

As shown in FIG. 10, in the present embodiment, of the transport guides 41 and 42 forming the guide surfaces on both sides of the document sheet Sc, the upper transport guide 41 is aligned with the direction in which the cross section of the document transport path 14 is enlarged. A recessed recessed portion 48 that is recessed upward in the figure and opens downward is formed.

This recessed portion 48 is within a wide range from near the downstream end of the transport guide 42 to the separation and feeding mechanism 22 side of the document transport distance from the nip portion 22a of the separating and feeding mechanism 22 to the nip portion 24a of the registration roller 24. In addition, the cross section of the document transport path 14 is expanded in the direction perpendicular to the paper surface of the document sheet Sc. Collision with the guide 41 can be effectively suppressed.

Further, the conveying distance from the nip portion 24a of the registration roller 24 (impact roller) to the document abutment sensor 23, which is the document detection means, is set so that the document abutment 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 transport distance from the paper feed belt 53 to the registration roller 24 .

In the present embodiment as well, by effectively suppressing the amount of deflection of the document sheet Sc abutted against the registration rollers 24, the sound generated when the document sheet Sc is deflected or the shape of the deflection is suddenly changed, It is possible to provide a sheet conveying device and an image reading device using the sheet conveying device that can effectively suppress the generation of collision noise when the bent document sheet Sc collides with any of the conveying guides 41 to 43. .

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

As shown in FIG. 11, in the present embodiment, in the conveyance guide 41 forming the guide surface on the main document surface side of the document sheet Sc, the lower surface of the low inclination angle portion on the side of the registration roller 24 is provided with the deflection of the document sheet Sc. A cushioning material 61 is provided to reduce impact noise when the document sheet Sc strikes the conveying guide 41 due to shape change or the like.

In addition, the distance from the registration roller 24 (impact roller) to the document contact sensor 23 is 30% or less of the document transport distance from the paper feed belt 53 to the registration roller 24. positioned.

The material of the cushioning material 61 is, for example, urethane with a PET (polyethylene terephthalate) material sheet attached to the surface. It is pasted along the side guide surface.

In the present embodiment as well, by effectively suppressing the amount of deflection of the document sheet Sc abutted against the registration rollers 24, the sound generated when the document sheet Sc is deflected or the shape of the deflection is suddenly changed, It is possible to provide a sheet conveying device and an image reading device using the sheet conveying device that can effectively suppress the generation of collision noise when the bent document sheet Sc collides with any of the conveying guides 41 to 43. .

As described above, the present invention effectively suppresses the amount of deflection of the sheet that has been hit by the hitting roller, thereby reducing the collision noise and the like when the sheet that has been bent due to the hitting collides with the conveying guide. It is possible to provide a sheet conveying device and an image reading apparatus using the sheet conveying apparatus that can effectively suppress the generation of the document sheet. It is useful for a sheet conveying device suitable for , and an image reading device using the same in general.

1 image forming apparatus 1A image forming apparatus main body 10 image reading device 11 document table 12 stop pawl 12a stop pawl shaft 14 document conveying path 15 set detection filler 16 document set sensor 18 nail HP sensor 20 document conveying device 21 pickup roller 22 separate paper feeding Mechanism (sheet feeding section)
22a nip portion 23, 23a, 23b document abutment sensor (document detection means, document detection sensor)
24 registration roller (impact roller)
24a Nip portion 25 Read entrance sensor 26 Read entrance roller 28 Read exit roller 29 Exit sensor 30 Paper discharge roller 31 Paper discharge tray 32 Registration roller 33 Document width sensor 35, 36 Document length sensor 41 Conveyance guide (Conveyance guide)
42 transport guide (transport guide on deflection limit side)
43 Conveyance guide (conveyance guide forming the introduction guide surface)
44, 45, 46 Conveyance guide 47 White reference guide 48 Recessed portion 51, 52 Pulley 51a Rotation drive shaft 52a Movable side belt support shaft 53 Paper feed belt 54 Reverse roller 55, 56 Roller pair 61 Cushion material 70 Controller 71 Call motor 72 Paper feeding motor 73 Reading motor 74 Paper ejection motor 101 Placed original image reading section (original image reading section)
101a flatbed contact glass 102 conveyed original image reading unit (original image reading unit)
108 operation unit 111 main body control unit 120 image forming unit 130 paper feeding unit 140 transfer paper transport unit 141 first transport path 142 second transport path 143 switching claw 150 fixing unit 160 paper ejection unit 161 paper ejection tray 170 post-processing device 171 Ejection tray A Document setting section B Separate feeding section (sheet feeding section)
C Registration Section D Turn Section E Scanning Conveyance Section F Back Side Scanning Conveyance Section G Paper Ejection Section H Stack Section Sc Original Sheet (Sheet)
SP Bundle of documents (sheet bundle)
P1 reading position (predetermined working position)
P2 Document detection position θ Nip angle

JP-A-2002-240963 Japanese Patent Application Laid-Open No. 2001-220026

Claims (9)

A sheet conveying device for conveying a cut sheet to a predetermined work position,
a sheet feeding unit that conveys the sheet in a feeding direction;
a pair of upper and lower abutting rollers for correcting skew of the sheet by abutting against a nip portion after the tip portion of the sheet fed from the sheet feeding portion abuts;
an upper conveying guide that limits an upper bending direction of the fed sheet from the sheet feeding portion to the nip portion of the impinging roller;
a lower conveying guide forming a conveying surface for the sheet separated and fed from the sheet feeding unit;
sheet detection means for detecting, at a sheet detection position, the leading edge of the sheet fed from the sheet feeding unit;
The lower conveying guide is linearly downwardly inclined from the sheet feeding portion with respect to the sheet insertion reference plane orthogonal to the axial center arrangement plane of the abutting roller, and is projected on an extension of the downwardly inclined line. There is a lower roller among the contact rollers,
When the sheet is fed from the sheet feeding portion to the nip portion, the leading end portion of the sheet contacts the lower roller,
After the leading edge of the sheet is detected by the sheet detection means at the sheet detection position, the sheet is transported, pressed against the nip portion, and transported by the sheet feeding portion is abutted and transported. The butt amount, which is the distance to be
A sheet characterized by being limited to a value smaller than a feed amount at which the feed sheet abuts against the upper conveying guide when the feed sheet abutted against the abutting roller bends in the warping direction. Conveyor. 2. The sheet according to claim 1, wherein the amount of contact with the contact roller is 7% or less of the sheet conveying distance from the nip portion of the sheet feeding portion to the nip portion of the contact roller. Conveyor. 3. The sheet conveying apparatus according to claim 1, further comprising abutting amount changing means for changing said abutting amount in accordance with the sheet feeding speed of said sheet feeding portion. The distance from the nip portion of the impingement roller to the sheet detection position is 30% or less of the conveying distance from the nip portion of the sheet feeding portion to the nip portion of the impingement roller. The sheet conveying device according to any one of claims 1 to 3. 5. The sheet conveying apparatus according to claim 1, wherein the guide surface of the upper conveying guide is provided with a recessed portion recessed in the bending direction. 6. A cushioning material is provided along the guide surface between the sheet feeding section and the abutment roller and on the guide surface of the upper conveying guide. 1. The sheet conveying device according to claim 1. the sheet detection means includes a plurality of sheet detection sensors spaced apart in a direction orthogonal to the feeding direction between the sheet feeding portion and the abutment roller;
7. The sheet conveying apparatus according to claim 1, further comprising control means for variably controlling the amount of contact based on sheet leading edge detection information from the plurality of sheet detection sensors. . a sheet conveying device according to any one of claims 1 to 7;
and a document image reading unit that reads an image of the sheet-shaped document conveyed to the predetermined work position. an image reading device according to claim 8;
and an image forming apparatus main body that forms an output image based on the image data of the document read by the image reading device.

Images