JP2014237497A - Sheet transport device, image reading device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet transport device, an image reading device, and an image forming apparatus, which are capable of correcting a skew reliably even for a sheet having a large length in a transport direction.SOLUTION: A sheet transport device includes: a set of alignment plates 505a, 505b for regulating and aligning both ends, in a width direction, of a document pile DG stacked on a tray; a slide mechanism for sliding the set of alignment plates 505a, 505b in a direction approaching, or separating from, each other; and a control part for controlling the slide mechanism. Further, the control part executes so that: the document pile DG is aligned by the set of alignment plates 505a, 505b (Fig. 7 (a)); an upper-most document D is extracted (Fig. 7 (b)); then the set of alignment plates 505a, 505b are moved in a separating direction E1; and the document pile DG is released from the regulation by the set of alignment plates 505a, 505b.

Description

  The present invention relates to a sheet conveying apparatus, an image reading apparatus and an image forming apparatus provided with the sheet conveying apparatus, and more particularly to a technique for correcting sheet skew.

An image forming apparatus such as a copying machine includes a document transport device that feeds out documents placed on a tray one by one and transports them to an image reading position (for example, Patent Document 1).
In general, such a document conveying device has a pair of documents that are placed on the tray so as not to be conveyed to the image reading position in a tilted state by abutting and aligning with both ends in the width direction perpendicular to the conveying direction. An alignment plate is provided, and a registration roller pair for correcting skew of the conveyed document is provided at a position upstream of the image reading position on the conveyance path. Document skew correction is performed by correcting the posture by bringing the leading edge of the document into contact with the nip portion of the registration roller pair in a rotation stopped state to form a loop and rotating the back of the document by the restoring force of the document. After the skew correction, the document roller is transported toward the image reading position by rotating the registration roller pair.

JP 2011-79593 A

However, in the conventional document feeder, document skew correction by the registration roller pair may not be sufficiently performed.
In other words, depending on the size of the original, the rear part of the original may remain between the pair of alignment plates at the time of loop formation. In this case, the movement of the rear part of the original is regulated by the pair of alignment plates. Even if the restoring force acts, it is difficult to correct the posture by rotating the rear part of the document, and there is a possibility that the skew correction is not sufficiently performed. As a result, the read image may be skewed and image quality may be degraded.

Such a problem becomes more prominent as the apparatus becomes smaller and the distance between the tray and the registration roller pair becomes shorter. Further, this is a problem that may occur not only in the document conveying device but also in general sheet conveying devices including a sheet feeding conveying device that conveys a recording sheet for printing an image.
The present invention has been made in view of the above problems, and provides a sheet conveying apparatus, an image reading apparatus, and an image forming apparatus that can reliably perform skew correction even when the length of the sheet in the conveying direction is long. The purpose is to do.

  In order to achieve the above object, the sheet conveying apparatus according to the present invention feeds the sheets one by one from the sheet bundle placed on the tray, and the leading edge of the sheet contacts the nip portion of the registration roller pair in the rotation stopped state. After making contact and forming a loop to correct the skew, the pair of registration rollers is rotated to convey the sheet, and the sheet bundle placed on the tray is in the sheet width direction orthogonal to the conveyance direction. A pair of alignment members that align and regulate both ends, a restriction release unit that releases the restriction of the sheet bundle by the pair of alignment members, and the sheet bundle after the sheet bundle is aligned by the pair of alignment members The regulation release means is configured to release the regulation of the sheet bundle by the pair of alignment members until the sheet fed out from the pair is started to be conveyed by the registration roller pair. Characterized in that it comprises a Gosuru control means.

  A sheet size acquisition unit configured to acquire a sheet size of the sheet bundle placed on the tray, and the control unit stops the leading edge of the sheet when the length of the acquired sheet size in the sheet conveyance direction is The restriction release means is controlled only when the trailing edge of the sheet is positioned between the pair of alignment members when being brought into contact with the nip portion of the registration roller pair in the state. It is desirable that the regulation of the sheet bundle is cancelled.

Furthermore, a paper type information acquisition unit that acquires information about the paper type of the sheets constituting the sheet bundle is provided, and the control unit acquires the paper type information in addition to the length condition of the sheet size in the sheet conveyance direction. When the thickness of the sheet is determined to be greater than or equal to a predetermined value based on the information acquired by the means, it is desirable to release the restriction on the sheet bundle by controlling the restriction release means.
The pair of alignment members in a state in which the restriction on the sheet bundle is released is provided with a returning unit that returns the sheet bundle to a state in which the sheet bundle is regulated and aligned, and the control unit removes the sheet bundle from the sheet bundle. Each time the predetermined number of sheets are fed out, the return means is controlled after the entire predetermined number of sheets are pulled out from between the pair of alignment members until the next sheet feeding is started. The pair of alignment members regulates and returns the sheet bundle to a state of alignment, and then the regulation release means is released until the next sheet is fed out and started to be conveyed by the registration roller pair. It is desirable to control and release the regulation of the sheet bundle by the pair of alignment members.

Here, it is desirable that the predetermined number of sheets is set according to the paper type of the sheets constituting the sheet bundle.
Further, it is desirable that the predetermined number be changed according to the remaining sheet amount of the sheet bundle.
Here, there is provided a start instruction receiving means for receiving from a user a start instruction of a sheet conveying operation for feeding and conveying sheets one by one from the sheet bundle, and the timing for releasing the regulation of the sheet bundle by the pair of alignment members is The configuration may be such that it is after the start instruction of the sheet conveying operation is received via the start instruction receiving means.

In addition, the timing of releasing the regulation of the sheet bundle may be a timing after the start instruction of the sheet conveying operation is received via the start instruction receiving unit and the operation of feeding out the sheet from the sheet bundle is started. .
Furthermore, the apparatus includes a mixed sheet receiving unit that receives from the user an instruction that a sheet bundle to be conveyed is mixed with sheets having different sheet widths, and the control unit receives sheets having different sheet widths via the mixed sheet receiving unit. When it is accepted that the sheets are mixed, the timing of releasing the regulation of the sheet bundle by the pair of alignment members is after the leading edge of the fed sheet comes into contact with the nip portion of the registration roller pair in the rotation stopped state. In addition, the restriction release unit may be controlled.

  Sheet size acquisition means for acquiring the sheet size of the sheet bundle placed on the tray, and start instruction reception means for receiving from the user an instruction to start a sheet conveyance operation for feeding and conveying sheets one by one from the sheet bundle And the timing for releasing the regulation of the sheet bundle by the pair of alignment plates is before the start instruction of the sheet conveying operation is received via the start instruction receiving unit, and the sheet size is acquired by the sheet size acquiring unit. It is also possible to have a configuration after acquiring

The present invention may be an image reading apparatus provided with the sheet conveying apparatus having the above-described configuration.
Further, the present invention may be an image forming apparatus including the sheet conveying device having the above-described configuration.

According to the sheet conveying apparatus configured as described above, even when the length of the sheet in the conveying direction is long and the rear portion of the sheet remains between the pair of alignment members at the time of loop formation, conveyance of the sheet is started by the pair of registration rollers. In the meantime, the regulation of the sheet bundle by the pair of alignment members is released, so that the posture can be corrected by rotating the rear portion of the sheet by the restoring force of the sheet.
As a result, the skew correction can be reliably performed, and the image quality can be prevented from being deteriorated due to insufficient skew correction.

1 is a schematic cross-sectional view for illustrating an overall configuration of a copier according to a first embodiment of the present invention. FIG. 2 is an enlarged view showing a configuration of an ADF unit included in the copying machine. It is the schematic plan view which looked at the ADF unit from the upper part. (A) is a top view which shows the structure of a slide mechanism of a pair of alignment board, (b) is the figure which looked at the slide mechanism of (a) from the arrow F direction. It is a block diagram which shows the relationship between the structure of a control part, and the main component used as the control object by a control part. 4 is a flowchart showing a part of control contents of a document conveying process executed by a control unit. (A)-(e) is an operation | movement diagram which shows operation | movement of a pair of alignment board in a document conveyance process. 10 is a flowchart illustrating a part of control content of a document conveyance process executed by a control unit according to a second embodiment. 10 is a flowchart illustrating a part of control content of document conveyance processing by a control unit according to a third embodiment. (A)-(d) is an operation | movement diagram which shows operation | movement of a pair of alignment board in the document conveyance process in 3rd Embodiment. It is a figure for demonstrating the determination criteria of whether the control cancellation | release by a pair of alignment board is performed in the control part which concerns on 4th Embodiment. 14 is a flowchart illustrating a part of control contents of document conveyance processing in the fourth embodiment. (A)-(c) is a figure which shows the structure of cancellation | release of the restriction | limiting of the document bundle | flux by a pair of alignment plate which concerns on a modification. It is a figure which shows the structure of cancellation | release of restriction | limiting of the document bundle | flux by a pair of alignment plate which concerns on a modification. 10 is a flowchart illustrating a part of control content of document conveyance processing by a control unit according to a modification. 10 is a flowchart illustrating a part of control content of document conveyance processing by a control unit according to a modification. FIG. 10 is an operation diagram showing an operation of a pair of alignment plates during document conveyance processing in a modified example.

<First Embodiment>
Hereinafter, a case where the first embodiment of the sheet conveying apparatus according to the present invention is applied to an original conveying apparatus in an image reading apparatus of a tandem type color copying machine (hereinafter simply referred to as “copier”) will be described with reference to the drawings. I will explain.
(1) Overall Configuration of Copying Machine FIG. 1 is a schematic cross-sectional view for illustrating the overall configuration of a copying machine according to the present embodiment.

The copying machine 1 shown in FIG. 1 includes a printer unit 2 and an image reading unit 3 (image reading device) provided on the printer unit 2. The copying machine 1 is connected to a network (for example, a LAN), and is configured to be able to transmit and receive data with an external terminal device.
(1-1) Configuration of Printer Unit The printer unit 2 includes an image forming unit 10, a paper feeding unit 20, and a control unit 30. The printer unit 2 transmits image data generated by the image reading unit 3 or an external terminal device. Based on the received image data, a toner image is printed on the recording sheet S by a known electrophotographic method.

The image forming unit 10 includes image forming units 11Y, 11M, 11C, and 11K corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer belt 12, two A next transfer roller pair 13, a fixing unit 14, a paper discharge tray 15 and the like are provided.
The image forming units 11Y, 11M, 11C, and 11K form toner images of corresponding colors under the control of the control unit 30, and electrostatic transfer (primary transfer) to the intermediate transfer belt 12 so that the toner images of the respective colors overlap each other. ) The intermediate transfer belt 12 is an endless belt, rotates in the direction of arrow A, and conveys the toner image to the secondary transfer position 16.

The paper feeding unit 20 includes a plurality of paper feeding cassettes 21 that store the recording sheets S, feeds the recording sheets S from one of the paper feeding cassettes 21 one by one, and matches the timing of the toner image on the intermediate transfer belt 12. To the secondary transfer position 16.
The recording sheet S on which the toner image (unfixed image) is formed by the secondary transfer is conveyed to the fixing unit 14, and the toner image is heated and pressurized in the fixing unit 14 and thermally fixed on the recording sheet S. The The thermally fixed recording sheet S is discharged onto the paper discharge tray 15.

The control unit 30 controls the image forming unit 10, the paper feeding unit 20, and the image reading unit 3 described below. Details will be described later.
(1-2) Configuration of Image Reading Unit The image reading unit 3 includes a scanner unit 40 that reads a document image, and an ADF unit (automatic document transport device) 50 that transports the document to the document reading position of the scanner unit 40.

The scanner unit 40 includes a light source unit 41, a mirror unit 42, a lens 43, a line sensor 44, and the like in a housing 400 in which first and second platen glasses 45 and 46 are fitted on the upper surface.
The light source unit 41 includes a lamp 411 serving as a light source, a mirror 412 and the like, and the mirror unit 42 includes folding mirrors 421 and 422 and the like. The line sensor 44 is composed of a CCD (Charge Coupled Device) having a plurality of photoelectric conversion elements.

  The scanner unit 40 includes a mirror scan mode for reading an image of a document placed on the first platen glass 45 by moving the light source unit 41 and the mirror unit 42 in the direction of arrow B by a slide mechanism (not shown), and ADF. When the document placed on the document feed tray 502 of the unit 50 is transported and passes over the second platen glass 46, the document image is read by selectively executing the sheet-through mode for reading the image.

(1-3) Configuration of ADF Unit The ADF unit 50 is attached to the scanner unit 40 by a hinge mechanism (not shown) so that the front side (the front side of the paper) can be opened and closed. Thus, when reading the document in the mirror scan mode, the ADF unit 50 can be opened upward and the document can be placed on the first platen glass 45.

The configuration of the ADF unit 50 will be described with reference to the enlarged view of FIG.
In the document feed tray 502, a stack of documents (not shown) placed thereon is lifted, and a lift plate 502a for placing the uppermost document at a position where it can be fed by the pickup roller 51, and a lift plate 502a. And an upper surface detection sensor S20 (see FIG. 5) for detecting the upper surface position of the document bundle.

  The elevating plate 502a is rotated (lifted / lowered) about the rotating shaft 502b by, for example, a stepping motor M5 (hereinafter referred to as “elevating motor M5”). The upper surface detection sensor S20 includes, for example, a known distance measurement sensor, and outputs the distance to the upper surface of the document bundle to the control unit 30. The control unit 30 acquires the position of the upper surface of the document bundle from the output result from the upper surface detection sensor S20, and controls the rotational drive of the lifting motor M5 so that the position of the upper surface becomes a preset height position. Then, the elevating plate 502 a is raised, so that the uppermost document is placed at a position where it can be fed out by the pickup roller 51.

Here, “original bundle” means one or more originals.
The ADF unit main body 501 includes a pickup roller 51, a separating unit 52, a registration roller pair 53, first to third transport roller pairs 54 to 56, a discharge roller pair 57, a CCD line sensor 58 for reading a back surface, and the like. When reading the original in the sheet through mode of the unit 40, the original is conveyed as follows.

First, a bundle of documents (not shown) placed on the document feed tray 502 is unwound by the pickup roller 51 in order from the topmost document, and is rolled when passing through the separation nip N1 of the separation section 52. Each sheet is fed toward the registration roller pair 53, where skew correction is performed.
Here, “skew correction” refers to forming a loop by bringing the edge on the leading end side of the document into contact with the registration nip N2 of the stopped registration roller pair 53, and conveying the original sheet by the waist of the document in the loop portion. This refers to correcting the inclination in the direction.

  The separating unit 52 includes a sheet feeding roller 521 (with a one-way clutch) and a sheeting roller 522 that is pressed against the sheet feeding roller 521. A torque limiter (not shown) that restricts the rotation is attached to the rotating shaft of the rolling roller 522. Thereby, when two or more originals are conveyed to the separation nip N1, the conveyance of the original on the side of the separation roller 522 is prevented by the separation roller 522 whose rotation is limited (stopped) by the torque limiter. It is burned.

  The original after skew correction is conveyed further downstream by the registration roller pair 53 and the first to third conveyance roller pairs 54 to 56, and passes through the original reading position P on the second platen glass 46 in the middle thereof. The image on the first surface (the second platen glass 46 side) is read by the line sensor 44 of the scanner unit 40. When performing double-sided copying or double-sided scanning, an image on the second side (side opposite to the first side) of the document is read by the CCD line sensor 58 for reading the back side. The document from which the image has been read is discharged from the discharge roller pair 57 onto the document discharge tray 503.

  The pickup roller 51 and the paper feed roller 521 of the separating unit 52 are rotationally driven by a transport drive motor M1 (hereinafter also referred to as “paper feed motor M1”). Among these, a paper feed clutch CL made up of an electromagnetic clutch is inserted in the power transmission path between the pickup roller 51 and the paper feed motor M1, thereby performing transmission control of the rotational driving force. The registration roller pair 53 is rotationally driven by a conveyance drive motor M2 (hereinafter also referred to as “registration motor M2”), and the first to third conveyance roller pairs 54 to 56 are connected to the conveyance drive motor M3 and the discharge roller pair. 57 are each driven to rotate by a conveyance drive motor M4.

Document transport sensors S1 to S3 for detecting a document to be transported are provided on a transport path 510 from the separating unit 52 to the document reading position P. The document transport sensor S1 is disposed at a downstream position in the transport direction of the separation unit 52, the document transport sensor S2 is disposed at an upstream position of the registration roller pair 53, and the document transport sensor S3 is disposed at an upstream position of the document reading position P. Yes.
The document transport sensors S1 to S3 are formed of, for example, a reflection type photoelectric sensor. Output. The control unit 30 detects the leading edge and the trailing edge of the document from the rising edge (change point from Low to Hi level) and the falling edge (change point from Hi to Low level) of the output of the document transport sensors S1 to S3, respectively. It is possible to detect that each of the document transport sensors S1 to S3 has passed, and based on the detection result, the rotation drive of each of the transport drive motors M1 to M4 is controlled to perform document transport and document skew correction. Control the behavior.

FIG. 3 is a schematic plan view of the document feed tray 502 and the ADF unit main body 501 as viewed from above.
As shown in the figure, the document feed tray 502 has a pair of alignment plates 505a and 505b. The pair of alignment plates 505a and 505b are slidable in the direction of approaching and separating from each other, and abut against both edges of the document D placed on the document feed tray 502 in the width direction (direction H perpendicular to the conveyance direction C). The original D is aligned so as to be parallel to the transport direction C. As will be described later, the document feed tray 502 is configured such that a pair of alignment plates 505a and 505b move symmetrically with respect to the center line L1, and is a so-called center reference method.

A reference wall 504 for positioning the leading edge of the document D is provided on the downstream side in the transport direction C of the document feed tray 502 (see also FIG. 2).
Further, the document feed tray 502 is provided with three document placement sensors S11 to S13 at a predetermined interval in the transport direction C. The document placement sensor S11 is a position that can be detected even when a document of a minimum size (here, A5 horizontal) in the transport direction C that can be transported by the ADF unit 50 is placed (all sizes of documents that can be transported). Is located at a position where it can be detected. The document placement sensor S12 is disposed at a position where a document having a size larger than B5 longitudinal can be detected, and the document placement sensor S13 is disposed at a position where a document having a size larger than B4 longitudinal can be detected. Here, the maximum size that can be transported is A3 vertical.

  Each document placement sensor S11 to S13 includes, for example, a known actuator switch, and outputs an ON signal to the control unit 30 when the document D is placed and the actuator is pressed. The control unit 30 determines the document size of the document D placed on the document feed tray 502 based on the output results from the document placement sensors S11 to S13 and the width dimension of the document D acquired as described later. (For example, A5 landscape, B6 portrait, etc.) are determined and acquired.

  Specifically, when the document placement sensor S11 is on and the other document placement sensors S12, S13 are off, the document sizes are A5 landscape, B6 portrait, A5 portrait, B5 landscape, A4 landscape. Limited to 5 types. Therefore, for example, if the width of the original D at this time is equal to the B6 vertical width (128 mm), the original size is determined to be B6 vertical width, and the width of the original D is A5 horizontal width (210 mm). ), It can be determined that the document size is A5 horizontal. When the document placement sensors S11 and S12 are on and the document placement sensor S13 is off, the document size is either B5 portrait or A4 portrait (B4 landscape and A3 landscape are not transportable). ) When all the document placement sensors S11 to S13 are on, the document size is either B4 portrait or A3 portrait. Therefore, also in these cases, the document size can be determined based on the width of the document D.

Further, the control unit 30 can determine whether or not a document bundle is placed on the document feed tray 502 by referring to the output of the document placement sensor S11.
As the document placement sensors S11 to S13, a reflective photoelectric sensor may be used instead of the actuator switch. In addition, for the document transport sensors S1 to S3, a contact type limit switch may be used instead of the reflective photoelectric sensor. Each sensor can be appropriately selected according to the specification of the ADF unit 50 and the like.

  The pickup roller 51 has a roller 51b attached to the rotation shaft 51a, and is arranged so that the center of the roller 51b in the axial direction is positioned on the center line L1 in the width direction H of the transport path 510. Further, the paper feed roller 521 of the winding unit 52 is disposed so that the center of the roller 521b attached to the rotation shaft 521a is located on the center line L1. The rolling roller 522 also has one roller attached to the rotation shaft, and is arranged so that the center of the roller in the axial direction is located on the center line L1 of the transport path 510.

  Since the lower roller in FIG. 3 is hidden in the registration roller pair 53, when viewed from the upper roller, the upper roller 531 has seven rollers 531b to 531h attached to the rotation shaft 531a. The center of the middle roller 531e in the axial direction is located on the center line L1, and the rollers 531b to 531d and the rollers 531f to 531h are arranged at symmetrical positions with respect to the center line L1 on both sides thereof. The rollers 531d and 531f immediately on both sides of the middle roller 531e are arranged corresponding to the document widths of B6 longitudinal and A5 longitudinal. The outer rollers 531c and 531g correspond to the B5 vertical and A4 vertical document widths, and the outer rollers 531b and 531h correspond to the B3 and A3 vertical document widths, respectively. Has been. The configuration of the lower roller is the same.

As described above, the rollers 531b to 531h are arranged corresponding to the originals of the respective widths, thereby ensuring the stability during conveyance irrespective of the original width.
Further, the roller pairs 54 to 57 (see FIG. 2) on the downstream side of the registration roller pair 53 are also similar to the registration roller pair 53. Each of the upper and lower rollers has seven rollers, respectively, with respect to the center line L1. Are configured to be symmetrical.

The number of rollers in each roller is not limited to seven. For example, the number of rollers may be six or less, or eight or more. The number and arrangement of rollers in each roller can be appropriately selected according to the specifications of the ADF unit 50.
(1-4) Configuration of Slide Mechanism of Pair of Alignment Plates FIG. 4A is a plan view showing the configuration of a slide mechanism 70 that slides the pair of alignment plates 505a and 505b in the proximity or separation direction.

As shown in the figure, in the present embodiment, a rack and pinion mechanism is adopted as the slide mechanism 70, and two rack rods 72a provided with a pinion 71 and a tooth row meshing with the pinion 71 are provided. , 72b, and a pinion drive motor M6 for rotating the pinion 71 via the timing belt 73, and the like.
The rack rods 72a and 72b are arranged in parallel to the width direction H with the pinion 71 interposed therebetween, and are slidably held in the width direction H by a support frame (not shown). The alignment plate 505a is connected to the connecting portion 721a of the rack rod 72a, and the alignment plate 505b is connected to the connecting portion 721b of the rack rod 72b (see also FIG. 4B).

As a result, the rack rods 72a and 72b move in the width direction H in opposite directions by the rotation of the pinion 71, so that the pair of alignment plates 505a and 505b maintain symmetry with respect to the center line L1 (FIG. 3). However, it is configured to be close to or away from each other.
The pinion drive motor M6 is formed of a stepping motor, for example, and rotates the pinion 71 by rotating in a specified direction by a predetermined angle based on a control signal (including a drive pulse signal, a rotation direction signal, etc.) from the control unit 30. It has become. As a result, the pair of alignment plates 505a and 505b can be slid by a predetermined amount in the direction of approaching or separating.

Here, the pair of alignment plates 505a and 505b are slid in a direction away from each other by forward rotation of the pinion drive motor M6, and are slid in directions close to each other by reverse rotation. When the pinion drive motor M6 is not energized, the user can manually move the pair of alignment plates 505a and 505b close to and away from each other.
FIG. 4B is a view of the slide mechanism 70 as seen from the direction of arrow F in FIG.

As shown in the figure, a pulley 74 on which a timing belt 73 is stretched and a volume sensor S14 are connected to a rotation shaft 71a of the pinion 71, respectively.
The volume sensor S14 includes a known rotary variable resistor, and outputs a detection resistance value corresponding to the distance K1 between the pair of matching plates 505a and 505b to the control unit 30.
The control unit 30 can calculate and obtain the distance K1 from the output result of the volume sensor S14. The distance K1 corresponds to the width dimension of the document D aligned by the pair of alignment plates 505a and 505b.

The slide mechanism 70 is accommodated in a case 506 (FIG. 2) attached below the lifting plate 502a. The elevating plate 502a is formed with slide holes 507a and 507b (FIG. 3) through which the connecting portions 721a and 721b of the slide mechanism 70 are inserted, which are connected to a pair of alignment plates 505a and 505b arranged on the upper surface side. .
In this embodiment, a rack and pinion mechanism is used as a mechanism for moving the pair of alignment plates 505a and 505b close to and away from each other. However, the present invention is not limited to this. For example, a belt drive mechanism may be used.

(2) Configuration of Control Unit FIG. 5 is a block diagram illustrating a relationship between the configuration of the control unit 30 and main components that are controlled by the control unit 30.
As shown in the figure, the control unit 30 includes a CPU (Central Processing Unit) 31, a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a communication interface (I / F) unit 34, and an image data storage. A unit 35, a document size storage unit 36, and the like.

  The CPU 31 executes a program for controlling the image forming unit 10, the paper feeding unit 20, the scanner unit 40, the ADF unit 50, the operation panel 60, and the like. The ROM 32 is a storage that stores various programs executed by the CPU 31. The RAM 33 is a work area when the CPU 31 executes a program. The communication I / F unit 34 is an interface for connecting to a LAN such as a LAN card or a LAN board.

The image data storage unit 35 stores image data for printing input via the communication I / F unit 34 or the scanner unit 40.
The document size storage unit 36 stores document sizes (length and width dimensions) obtained from the output results of the document placement sensors S11 to S13 and the volume sensor S14.
The operation panel 60 is disposed at an easy-to-operate position on the upper side of the copier 1, and is a touch panel type liquid crystal display for displaying various information such as an operation screen such as a print setting screen and a print result, and for inputting various instructions. It consists of operation buttons and the like, and receives various instruction inputs from the user through operations such as a touch panel and operation buttons. Examples of the operation buttons include a start button 61 (start instruction receiving unit) that receives a start instruction for a copy job or a scan job.

Further, in the sheet through mode, the CPU 31 performs a “document transport process” in which the user sequentially feeds the topmost document from the document stack placed on the document feed tray 502 to the document reading position P.
During the document conveying process, after the document is fed out from the document bundle, the CPU 31 drives and controls the pinion drive motor M6, and executes control for repeatedly aligning the document bundle and releasing the restriction by the pair of alignment plates 505a and 505b. To do.

(3) Document Conveying Process FIG. 6 is a flowchart showing a part of the control content of the “document conveying process” executed by the control unit 30.
This control is carried out as a subroutine of a main flowchart (not shown) for controlling the entire copying machine 1, and here, mainly a pair of alignment plates 505a and 505b is used to align the document bundle and release the regulation. Control for is shown.
(3-1) Pre-Feeding Process As shown in FIG. 6, first, when the control unit 30 receives a copy or scan job via the operation panel 60 (step S101), a bundle of originals is placed on the original feed tray 502. Is checked (step S102). The control unit 30 refers to the output of the document placement sensor S11 and determines that the document bundle is placed if the ON signal is received.

  When the document bundle is placed (step S102: Yes) and the pair of alignment plates 505a and 505b are arranged at the alignment position of the document bundle (step S103: Yes), the control unit 30 causes the document placement sensors S11 to S13. And the document width obtained from the output result of the volume sensor S14, the size of the document bundle is determined and acquired, and stored in the document size storage unit 36 (step S104).

The determination as to whether or not the pair of alignment plates 505a and 505b are arranged at the alignment position of the document bundle can be performed as follows with reference to the output of the volume sensor S14, for example.
The output of the volume sensor S14 fluctuates corresponding to the distance K1 between the pair of alignment plates 505a and 505b while the pair of alignment plates 505a and 505b is moving in the direction of approaching or separating, and stops the movement. And stable (fixed). Accordingly, if the period during which the output of the volume sensor S14 is stable continues for a predetermined time (for example, between about 0.5 to 1.0 seconds), the control unit 30 can detect a pair of alignment plates. It can be determined that 505a and 505b are arranged at positions where the original bundle is aligned.
(3-2) Paper Feed Processing After the document size is acquired in step S104, when the user presses the start button 61 on the operation panel 60 and receives a copy job or scan job start instruction (step S105: Yes), The document feed is started (step S106).

  First, the control unit 30 raises the lifting plate 502a by controlling the rotational drive of the lifting motor M5 while monitoring the output result from the upper surface detection sensor S20 that detects the upper surface position of the document bundle, so that the uppermost position of the document bundle is reached. The upper document is arranged at a position where it can be fed by the pickup roller 51. Next, the control unit 30 rotationally drives the paper feed motor M1 and connects the paper feed clutch CL. As a result, the pickup roller 51 and the paper feed roller 521 are rotated to feed out the document placed on the document feed tray 502 and send it to the transport path 510.

If the time Ta required for raising the lifting plate 502a and starting the feeding of the document by the pick-up roller 51 has elapsed after the start of document feeding in step S106 (step S107: Yes), the control unit 30 sets a pair. The restriction of the original bundle by the alignment plates 505a and 505b is released (step S108).
Here, the restriction on the document bundle is released by sliding the pair of alignment plates 505a and 505b by a predetermined amount Sr (for example, about 5 mm) by controlling the pinion drive motor M6 to rotate forward at a predetermined angle. The alignment plates 505a and 505b are separated from the original bundle (see FIG. 7B). The value of the time Ta is obtained in advance at the design stage.

FIGS. 7A to 7E are operation diagrams showing the operation of the pair of alignment plates 505a and 505b during the document conveying process.
FIG. 7A shows a pair of alignment plates 505a and 505b arranged at positions where the document bundle DG is aligned before the start of document feeding. When feeding is started and the uppermost document D of the document bundle DG is fed out by the pickup roller 51, as shown in FIG. 7B, the pair of alignment plates 505a and 505b slide in the separating direction E1. Then, the restriction on the document bundle DG is released.

If the leading edge of the fed document D passes through the position of the document conveyance sensor S1 on the downstream side of the separation unit 52, the control unit 30 releases the sheet feeding clutch CL and causes the sheet feeding motor M1 to rotate the pickup roller 51. Stop. Thereafter, the document D is conveyed by the paper feed roller 521. Further, the control unit 30 controls the rotational drive of the lift motor M5 at the timing of releasing the paper feed clutch CL to lower the lift plate 502a to prepare for the next document feed.
(3-3) Skew Correction Processing If the leading edge of the document D transported by the paper feed roller 521 passes the position of the document transport sensor S2 upstream of the registration roller pair 53 and further passes the time Tb, the registration motor M2 is turned on. The forward rotation is driven, and the conveyance of the original by the registration roller pair 53 is started.

  The time Tb here is the time Tb1 until the leading edge of the document that has passed the position of the document transport sensor S2 reaches the registration nip N2 of the registration roller pair 53, and the leading edge of the document has reached the registration nip N2. Thereafter, the time Tb2 required for conveying the trailing edge of the original document by about 3 mm, for example, is added. The time Tb1 is calculated from the transport distance from the position of the document transport sensor S2 to the registration nip N2 and the document transport speed. The time Tb2 is calculated from the transport distance of 3 mm and the document transport speed. During this time Tb2, the leading edge of the document is abutted against the registration nip N2 to form a loop, and skew correction is performed (see FIGS. 7C and 7D, step S109 in FIG. 6).

  At the time of this skew correction, the restriction of the document bundle by the pair of alignment plates 505a and 505b is released. Therefore, as shown in FIG. 7C, the movement in the width direction of the rear portion Dc of the document D is a pair of alignment plates. It is not restricted by 505a and 505b, and it becomes easy to correct the posture of the document D. As a result, the skew of the document can be reduced as compared with the conventional configuration in which the movement of the rear portion of the document is restricted by the pair of alignment plates.

  More specifically, in the case of the document D shown in FIG. 7C, the document is tilted to the left in the conveyance direction C. Therefore, the loop amount of the loop R is different between the left R1 and the right R2 (R2> R1). The restoring force is greater on the right side F2 than on the left side F1 (F2> F1). Accordingly, the posture of the original D is corrected by the action of F2 having a large restoring force so as to turn in the direction of the arrow T around the portion Q sandwiched by the separation nip N1 of the separation portion 52, and the skew is reduced. (FIG. 7D).

For example, as in the conventional configuration, when the pair of alignment plates 505a and 505b are at the alignment position of the document bundle DG (the position indicated by the broken line in FIG. 7C), the rear portion Dc of the document D is moved in the width direction. Since it is regulated by the pair of alignment plates 505a and 505b, the posture of the document D is hardly changed and the skew cannot be reduced sufficiently.
In step S108, the predetermined amount Sr for moving the pair of alignment plates 505a and 505b away from each other is measured in advance by measuring the range of skew amounts generated when a document is fed by an experiment, and based on the measurement results, skew correction is performed. At this time, the movement in the width direction of the rear portion Dc of the document D is set to a size that is not restricted by the pair of alignment plates 505a and 505b.

Returning to FIG. 6, after the skew correction in step S109, if the trailing edge of the document D passes through the separation nip N1 of the separation unit 52 (step S110: Yes), the paper feed motor M1 is stopped, and the next document is detected. It is confirmed whether there is any (step S111).
Here, whether or not the trailing edge of the document D has passed through the separation nip N1 is determined by referring to the output of the document conveyance sensor S1 on the downstream side of the separation unit 52 and setting the position of the document conveyance sensor S1 behind the document D. The configuration is performed depending on whether or not the end has passed. Further, whether or not there is a next document is determined by referring to the output of the document placement sensor S11.

If there is a next document (step S111: Yes), the control unit 30 returns the pair of alignment plates 505a and 505b to the alignment position for aligning the document bundle DG (step S112) (see FIG. 7E).
As a result, even when the uppermost document is fed out from the bundle of documents, even if the lower document is fed and skew occurs, it is possible to align and remove the skew before feeding the lower document. As compared with the case where the original is fed out with the skew remaining, it is possible to suppress the occurrence of a large skew in the supplied original.

Here, the movement of the pair of alignment plates 505a and 505b to the alignment position is performed when the alignment plates 505a and 505b are separated from each other in the direction E2 close to each other by controlling the pinion drive motor M6 to reversely drive by a predetermined angle. Is performed by sliding the same predetermined amount Sr.
The control unit 30 stops the registration motor M2 when the trailing end of the document D further passes through the registration nip N2 of the registration roller pair 53.

After step S112, the process returns to step S106, and the processes of steps S106 to S112 are repeated while there is a next original (step S111: Yes).
If there is no next original (step S111: No), the process returns to the main flowchart (not shown).
This completes the document conveyance process.

  According to the copying machine 1 configured as described above, even if the length of the document D in the conveyance direction is long and the rear portion of the document D remains between the pair of alignment plates 505a and 505b at the time of loop formation, the pair of alignment plates Since the restriction of the document bundle DG by 505a and 505b is released, the posture of the document D can be corrected by rotating the rear part of the document D by the restoring force of the document D, and skew correction can be more reliably performed.

In the present embodiment, when the slide mechanism 70 that moves the pair of alignment plates 505a and 505b closer to or away from each other moves the pair of alignment plates 505a and 505b arranged at positions for aligning the bundle of documents, It functions as a restriction release means for releasing the bundle restriction.
Further, when the slide mechanism 70 brings the pair of alignment plates 505a and 505b close to each other and returns them to the alignment position, the slide mechanism 70 functions as a return unit that regulates and returns the original bundle to the alignment state.

The control unit 30 functions as a control unit that controls the slide mechanism 70 that functions as a restriction release unit and a return unit.
The volume sensor S14 that acquires the distance K1 between the pair of alignment plates 505a and 505b corresponding to the width of the document, the document placement sensors S11 to S13, and the control unit 30 serve as document size acquisition means for acquiring the document size. Function.

<Second Embodiment>
The second embodiment is configured such that alignment by a pair of alignment plates 505a and 505b and release of regulation are performed each time a predetermined number of documents are fed, and alignment and regulation are performed each time one sheet is fed. This is different from the first embodiment in which the release is performed.
As a result, the frequency of alignment and release of regulation by the pair of alignment plates 505a and 505b can be reduced as compared with the first embodiment. Generation of motor driving noise can be reduced.

  Here, the “predetermined number of sheets” means that the alignment frequency of the document bundle is reduced as compared with the case where the alignment and the release of the regulation are repeated every time one sheet is fed, so that the original document is In order to prevent such a situation from occurring, there is a risk that the skew becomes large and the corner of the document tip may be crushed or the skew exceeding the allowable range may remain when the skew correction is performed by the registration roller pair 53. Desired. In the present embodiment, five sheets are set as the predetermined number.

Here, the “allowable range” of the skew specifically means that the skew angle (the inclination of the document with respect to the direction orthogonal to the conveyance direction C) is about −0.3 ° to + 0.3 °, and the ADF unit 50. These are revised according to the specifications of the scanner unit 40.
Since the other configuration is basically the same as that of the copying machine 1 of the first embodiment, the following description will mainly focus on the different parts of the “document conveying process”.

FIG. 8 is a flowchart showing a part of the control content of the “document conveying process” executed by the control unit 30 in the present embodiment. For convenience of explanation, a process different from the flowchart of FIG. 6 is included, step S105. The subsequent processing is shown. In addition, the same step number is attached | subjected about the same process as FIG.
As shown in FIG. 8, after step S105 (after pressing the start button), first, “1” is set to a counter CNT that counts the number of fed sheets (step S121).

Thereafter, as in FIG. 6, in steps S106 to S111, the feeding of the document is started, and after the time Ta has elapsed, the restriction of the document bundle by the pair of alignment plates 505a and 505b is released, and the document subjected to the skew correction. If the rear end of D passes through the separation nip N1 of the separation section 52, the presence or absence of the next document is confirmed.
If there is a next original (step S111: Yes), it is checked whether the counter CNT is 5 or more (step S122).

  If the counter CNT is not 5 or more (step S122: No), the value of the counter CNT is incremented (step S123), and feeding of the next document is started (step S124). Thereafter, returning to step S106, the processes of steps S106 to S111 and S122, S123 are repeated while the next original is present (step S111: Yes) and until the counter CNT becomes 5 or more (step S122: No). .

In step S122, when the counter CNT is 5 or more (Yes), the pair of alignment plates 505a and 505b is returned to the alignment position for aligning the original bundle (step S112), and the process returns to step S121 to set the counter CNT to “1”. And the processes of steps S106 to S111 and S122 to S124 are repeated.
Also in this embodiment, even when the rear portion of the document D remains between the pair of alignment plates 505a and 505b at the time of forming the loop of the document D, the restriction of the document bundle DG by the pair of alignment plates 505a and 505b is released. Therefore, the same effect as the first embodiment can be obtained.

<Third Embodiment>
In the third embodiment, during the document conveyance process, the alignment and the restriction release by the pair of alignment plates 505a and 505b are not repeated, and after the restriction of the document bundle by the pair of alignment plates 505a and 505b is released, This is different from the first embodiment in which the restriction is released and the restriction is released until the document feeding is completed.

As a result, it is possible to limit the generation of noises such as operation sounds and motor drive sounds due to the movement of the alignment plates 505a and 505b to one time during the document transport process, so that the generation of noises can be greatly suppressed. it can.
In this case, the remaining document bundle may be tilted and skew may be increased due to the document feed, etc. In this embodiment, the document transport speed by the paper feed roller 521 is decreased, The corner of the leading edge of the document is prevented from being crushed by the collision with the registration roller pair 53, and the time Tb2 for skew correction is the time required to transport the trailing edge of the document by about 3 mm (first embodiment). Thus, for example, by changing the time required for conveying about 5 mm, the amount of the original loop is increased, and the restoring force is increased to further reduce the original skew. These points are also different from the first embodiment.

Since the other configuration is basically the same as that of the copying machine 1 of the first embodiment, the following description will mainly focus on the different parts of the “document conveying process”.
FIG. 9 is a flowchart showing a part of the control content of the “document conveying process” executed by the control unit 30 in the present embodiment. For convenience of explanation, the steps after step S105 (pressing the start button) in FIG. Processing is shown. The same processes as those in FIG. 6 are given the same step numbers.

FIGS. 10A to 10D are operation diagrams showing the operation of the pair of alignment plates 505a and 505b during this processing.
As shown in FIG. 9, first, similarly to FIG. 6, in steps S106 to S111, the feeding of the first sheet from the bundle of documents is started, and after the time Ta has elapsed, the bundle of documents by the pair of alignment plates 505a and 505b. After the restriction is released (FIG. 10A) and the skew correction is performed (FIGS. 10B and 10C), if the trailing edge of the document D passes through the separation nip N1 of the separation portion 52, The presence or absence of the next document is confirmed (FIG. 10D).

When there is a next original (step S111: Yes), the control unit 30 starts feeding the next original without returning the pair of alignment plates 505a and 505b to the alignment position where the original bundle is aligned. (Step S131).
Thereafter, the process returns to step S109, and the processes of steps S109 to S111 and step S131 are repeated while there is a next original (step S111: Yes).

Also in this embodiment, even when the rear portion of the document D remains between the pair of alignment plates 505a and 505b at the time of forming the loop of the document D, the restriction of the document bundle DG by the pair of alignment plates 505a and 505b is released. Therefore, the same effect as the first embodiment can be obtained.
<Fourth embodiment>
The fourth embodiment is configured so as to determine whether or not to release the restriction by the pair of alignment plates 505a and 505b based on the length of the document in the conveyance direction. Is different.

  Specifically, the distance K2 (see FIG. 11) on the conveyance path 510 between the pair of alignment plates 505a and 505b and the registration nip N2 of the registration roller pair 53 is compared with the length in the document conveyance direction. In the case where the length of the document in the conveyance direction is longer than the distance K2, the restriction is released. In other cases, the restriction is not released. This is because if the length of the document in the conveyance direction is equal to or less than the distance K2, the rear portion Dc of the document D is not regulated by the pair of alignment plates 505a and 505b during skew correction, so that it is not necessary to release the regulation. As a result, unnecessary control can be eliminated, and the generation of operating noise and motor driving noise due to movement of the alignment plates 505a and 505b can be reduced.

In the present embodiment, the distance K2 is not less than the length of the A5 longitudinal document in the conveyance direction and less than the length of the A4 portrait document in the conveyance direction. Therefore, in the case of an A5 longitudinal document, No is determined in step S142, and the restriction is not released by the pair of alignment plates 505a and 505b.
Since the other configuration is basically the same as that of the copying machine 1 of the first embodiment, the following description will mainly focus on the different parts of the “document conveying process”.

FIG. 12 is a flowchart showing a part of the control content of the “document conveying process” executed by the control unit 30 in the present embodiment. For convenience of explanation, the processing after step S105 (pressing the start button) in FIG. 6 is performed. Processing is shown. The same processes as those in FIG. 6 are given the same step numbers.
In the present embodiment, the length of the distance K2 described above is stored in the ROM 32 in advance.

As shown in FIG. 12, the control unit 30 first reads and acquires the distance K2 from the ROM 32 (step S141).
Next, when the length of the document in the conveyance direction (obtained from the document size acquired in step S104 in FIG. 6) is longer than the distance K2 (step S142: Yes), as in FIG. The process of S112 is performed. Thereby, the alignment by the pair of alignment plates 505a and 505b and the release of the regulation are repeated.

  On the other hand, when the length of the document in the conveyance direction is equal to or shorter than the distance K2 (step S142: No), after the document feeding is started (step S143), the restriction by the pair of alignment plates 505a and 505b is not released. Then, skew correction is performed (step S144). Thereafter, if the trailing edge of the document D passes through the separation nip N1 of the separation unit 52 (step S144), the presence / absence of the next document is confirmed (step S146: Yes), and the process returns to step S143. The processes of S143 to S145 are repeated while the next original is present (step S146: Yes).

Also in the present embodiment, when the length of the document D in the conveyance direction is long and the rear portion of the document D remains between the pair of alignment plates 505a and 505b at the time of loop formation, the pair of alignment plates 505a. , 505b, the restriction on the original bundle DG is released, so that the same effect as in the first embodiment can be obtained.
[Modification]
As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described embodiment, and the following modifications can be implemented.

(1) Although not particularly mentioned in the above embodiment, the moving speed when moving the pair of alignment plates 505a and 505b may be different depending on whether they are close or separated.
In this case, when the pair of alignment plates 505a and 505b are returned to the alignment position by slowing the moving speed when they are brought close to each other, the original is prevented from buckling when it is brought into contact with the pair of alignment plates 505a and 505b. can do.

The controller 30 can switch the moving speed of the pair of alignment plates 505a and 505b by changing the input interval of the drive pulse signal to the pinion drive motor M6.
(2) In the above embodiment, the restriction of the document bundle by the pair of alignment plates 505a and 505b is released at the timing when the time Ta has elapsed after the document feeding starts and the document feeding by the pickup roller 51 is started. Although the structure to perform is shown, it is not limited to this.

For example, the restriction release by the pair of alignment plates 505a and 505b is performed after the leading edge of the document fed out by the pickup roller 51 passes through the separation nip N1 of the separation portion 52 or the registration roller pair 53 in the rotation stopped state. It may be performed at the timing of contact.
Further, even when the front end of the document is in contact with the registration roller pair 53 in the rotation stopped state and a loop is formed, the restoring force of the document is released by releasing the restriction by the pair of alignment plates 505a and 505b. This makes it easier to correct the posture by rotating the document, so that the skew correction effect can be enhanced as compared with the prior art.

If the restriction is released by the pair of alignment plates 505a and 505b before the registration roller pair 53 is rotated and the original is started to be conveyed by the registration roller pair 53, the original is rotated by the restoring force of the original to correct the posture. Therefore, the skew correction effect can be enhanced as compared with the prior art.
(3) In the second embodiment, the frequency of repeating alignment and deregulation by the pair of alignment plates 505a and 505b has been described using a configuration for feeding five originals, but the present invention is limited to this. It is not a thing.

For example, the frequency of repeating alignment and deregulation may be changed depending on the type of paper such as thick paper, plain paper, and thin paper.
Since paper is more likely to be fed with thin paper than thick paper or plain paper, alignment and deregulation are repeated more frequently when the original is thin, and alignment with the thick paper It is desirable to reduce the frequency of repeating deregulation. For example, it is configured to repeat alignment and deregulation by a pair of alignment plates 505a and 505b every two sheets for thin paper, every five sheets for plain paper, and every ten sheets for thick paper. Also good. Note that the number of sheets here is merely an example, and in reality, the skew caused by the carry of the document becomes too large for each paper type of the document. It is desirable to set based on an appropriate frequency of matching and deregulation that have been obtained in advance through experiments so as not to be crushed by an impact abutting on the surface or to leave a skew exceeding the allowable range.

  Also, according to experiments, in the case of a specific paper type (for example, thick paper), the document is hardly fed or even if it is caused, the corner of the document tip is crushed or a skew exceeding the allowable range remains. If it is confirmed that a large skew is not generated, the alignment and the deregulation by the pair of alignment plates 505a and 505b are not repeated only in the case of the specific paper type. The release state can also be maintained.

  The paper type information of the original is obtained when the user inputs paper type information (thin paper, plain paper, thick paper, etc.) from the operation panel 60 when setting the original on the original feed tray 502, or the original transport path Can be obtained by providing a sensor for detecting the thickness of the document in the middle of the document (for example, at a position downstream of the curling unit 52). In this case, the operation panel 60 or a sensor that detects the thickness of the document functions as a paper type information acquisition unit.

(4) Further, the frequency of repeating the alignment and deregulation may be switched according to the remaining document amount (number of sheets) placed on the document feed tray 502.
As the number of originals increases and the height of the original bundle increases, the skew of the sent originals tends to increase. Therefore, the higher the remaining number of originals, the more frequently the alignment and deregulation are repeated, and the remaining originals. As the number of sheets decreases, it is desirable to set the number of documents to be repeated so that the frequency with which alignment and deregulation are repeated is reduced. For example, in the case of plain paper, if the remaining number of documents is 20 or more, the frequency of repeating alignment and deregulation is set to every two sheets, and if the remaining number of documents is less than 20, alignment and deregulation are performed. It can be configured to switch the frequency of repeating every 5 sheets. The number here is merely an example, and is actually determined and set in advance by experiments.

The remaining number of originals (α) can be obtained from the thickness (β) of one original obtained from the paper type information of the original and the height (γ) of the original bundle (α = β / γ).
The height (γ) of the original bundle is, for example, a distance measurement different from that of the upper surface detection sensor S20 above an area outside the area on which the original of the maximum size (A3 longitudinal) is placed on the upper surface of the original paper feed tray 502. Obtained by arranging the sensor (A), detecting the upper surface position of the document bundle by the upper surface detection sensor S20, detecting the upper surface position of the document feed tray 502 by the distance measuring sensor (A), and obtaining the difference. It is done. Further, for example, the height (γ) of the document bundle may be obtained from the rotation angle of the lifting motor M5 that rotates the lifting plate 502a that arranges the uppermost document at a position where it can be fed by the pickup roller 51. it can.

(5) In the above embodiment, the configuration in which the restriction of the document bundle by the pair of alignment plates 505a and 505b is released by sliding the pair of alignment plates 505a and 505b apart in the document width direction. Although shown, it is not limited to this.
For example, as shown in FIG. 13A, the pair of alignment plates 205 a and 205 b are made to protrude to a position protruding from the document feed tray 502 (a position indicated by a solid line) and below the document feed tray 502. In order to release the restriction of the document bundle DG, the pair of alignment plates 205a and 205b are moved to the original feeding position (position indicated by a broken line) in the up-down direction J as shown in FIG. The restriction may be canceled by moving the paper tray 502 to the lower side.

  In this case, the alignment plates 205a and 205b are retracted to the lower side of the document feed tray 502, and the alignment plates 205a and 205b are arranged so that the width of the slide hole for sliding in the document width direction does not become too large. 205b has a comb shape. This is because if the width of the slide hole becomes too large, the original document slightly falls at the slide hole, resulting in unevenness on the surface of the original, and skew tends to occur when the original is fed out.

  Further, as shown in FIG. 13 (c), the upper ends of the alignment plates 205a and 205b are tapered to widen the frontage. As a result, when the alignment plates 205a and 205b are projected onto the document feed tray 502 and returned to the alignment position, the skewed document is prevented from running on the alignment plates 205a and 205b, and the document Both ends in the width direction are slid on the tapered surface so that they can be aligned.

The vertical movement of the pair of alignment plates 205a and 205b can be performed by, for example, a cam mechanism that vertically moves a support frame (not shown) that supports a slide mechanism attached to the pair of alignment plates 205a and 205b.
(6) Further, as shown in FIG. 14, the pair of alignment plates 305a and 305b may be tilted (turned) so as to fall outward, thereby releasing the restriction of the document bundle DG. The alignment plates 305a and 305b can be tilted (rotated) using, for example, motors M7 and M8. In place of the motors M7 and M8, a solenoid may be used.

(7) In the third embodiment, the document bundle restriction may be canceled by the pair of alignment plates 505a and 505b before the start of paper feeding.
For example, as shown in the flowchart of FIG. 15, after the start button is pressed by the user (step S105: Yes), the document bundle restriction by the pair of alignment plates 505a and 505b is released before the feeding is started (step S105: Yes). Step S151) A configuration may be adopted.

Further, as shown in the flowchart of FIG. 16, after the document size is acquired (step S104) and before the start button is pressed by the user (step S105: Yes), the pair of alignment plates 505a and 505b are used. A configuration may be adopted in which the restriction of the original bundle is canceled (step S161).
In FIG. 15 and FIG. 16, the same processes as those in FIG. 6 are denoted by the same step numbers.

(8) In the above embodiment, the center reference type document feed tray 502 has been described. However, the scope of application of the present invention is not limited to this. For example, the present invention is also applicable to a one side reference type document feed tray. can do.
FIGS. 17A to 17E are operation diagrams showing the operation of the pair of alignment plates 405a and 405b when the one-side reference type document feed tray 402 is used.

First, as shown in FIG. 17A, the pair of alignment plates 405 a and 405 b are arranged at positions close to the right side in the conveyance direction C of the document feed tray 402. The position of the alignment plate 405b here is the reference position, and the document bundle DG is aligned by moving the alignment plate 405a according to the width of the document bundle DG.
When feeding is started and the uppermost document D of the document bundle DG is fed out by the pickup roller 451, as shown in FIG. 10B, the pair of alignment plates 405a and 405b are respectively slid in the separating direction E1. Then, the restriction on the document bundle DG is released. Here, since the fed document D may be inclined to the right in the transport direction C, the alignment plate 405b at the reference position is also moved.

Thereafter, as shown in FIGS. 10C and 10D, the leading edge of the fed document D is abutted against the registration nip N2 of the registration roller pair 453 to form a loop, and skew correction is performed. .
After skew correction, if the document D is conveyed downstream by the rotation of the registration roller pair 453, and the trailing end of the document D passes through the separation nip N1 of the separation portion 452, a pair of pairs is obtained as shown in FIG. The alignment plates 405a and 405b are moved in the approaching direction E2 and returned to the alignment position for aligning the document bundle DG.

Thus, in the case of the one-side reference method, when the user places the document bundle DG on the document feed tray 402, the center reference method is different in that only one alignment plate 405a is moved and aligned. Although different, the subsequent operations (registration release and alignment operation) of the pair of alignment plates 405a and 405b have basically the same configuration as the center reference method.
Also, due to the above differences, the slide mechanism for sliding the pair of alignment plates 405a and 405b in the case of the one-side reference method is different from the center reference method, for example, a solenoid is attached to each of the alignment plates 405a and 405b, Each is configured to be independently slidable. A cam mechanism or a linear motor may be used instead of the solenoid.

If the direction in which the document D tilts is limited to the left side in the conveyance direction C opposite to the reference position side according to the specifications of the apparatus, the alignment plate 405b may be configured not to move.
For example, there is a case where the original is inclined to the left in the conveyance direction C from the beginning. In this case, if the adjustment is made so that the inclination to the left does not become too large, the posture of the document can be corrected by skew correction, so that it is possible to prevent the image quality from being lowered and to fix one alignment plate. Therefore, there is an advantage that the cost can be reduced because the sliding mechanism of the alignment plate is simplified accordingly.

(9) In the above embodiment, a description has been given using a configuration in which a document bundle made up of documents of the same size is placed on the document feed tray 502. However, the scope of application of the present invention is not limited to this, For example, the present invention can also be applied to a case where a so-called mixed-width document bundle having different widths mixed is placed.
Normally, in the case of a mixed document bundle of different widths, the user aligns one end in the width direction of the mixed document bundle (one side reference), and then places the pair on the document feed tray 502 and sets a pair according to the width of the largest document. The alignment plates 505a and 505b are moved. In this case, since the small-size document is not in contact with the alignment plate at the other end in the width direction, there is a possibility that the skew may increase due to feeding or the like before feeding out.

  For this reason, if the restriction by the pair of alignment plates 505a and 505b is released immediately after the original is fed out, the skew of the small-size original is larger than when the restriction by the pair of alignment plates 505a and 505b is maintained. Therefore, until the leading edge of the document comes into contact with the registration nip N2 of the registration roller pair 53, the pair of alignment plates 505a and 505b are arranged at the alignment position, and the leading edge of the document contacts the registration nip N2. After the contact, it is desirable that the restriction by the pair of alignment plates 505a and 505b is released.

For example, the operation panel 60 is provided with a different-width mixed mode setting button (mixed-document receiving unit) that accepts mixed-width originals, so that the user can change the mixed-width mode. This can be done depending on whether it is set.
(10) In the above embodiment, a configuration using the volume sensor S14 provided in the slide mechanism 70 is used to obtain the distance K1 between the pair of alignment plates 505a and 505b corresponding to the width dimension of the document D. Although shown, it is not limited to this.

For example, a distance measuring sensor may be attached to one of the facing surfaces of the pair of matching plates 505a and 505b, and the distance K1 to the other facing surface may be detected using the distance measuring sensor.
Further, without using such a sensor, the user can input the document size (A4 portrait, A4 landscape, etc.) from the operation panel 60 when placing the document on the document feed tray 502, so that the document size can be reduced. The obtained structure may be used.

(11) In the above-described embodiment, the configuration has been described in which the scooping member that scoops the document fed out by the pickup roller 51 is composed of the scooping roller 522, but is not limited thereto. For example, instead of a rolling roller, a rolling pad can be used as a rolling member.
(12) In the above-described embodiment, the configuration in which the ADF unit 50 is controlled using the control unit 30 provided (arranged) in the printer unit 2 has been described. However, the present invention is not limited to this. For example, the ADF unit 50 may have a dedicated control unit. In this case, the controller dedicated to the ADF unit 50 is configured to execute the document conveying process in cooperation with the controller 30 of the printer unit 2.

(13) In the above embodiment, the ADF unit in the image forming apparatus which is a copying machine has been described. However, the scope of application of the present invention is not limited to this. For example, the present invention can be applied to a paper feed cassette of a printer. Can do.
Even in the process of feeding out and transporting the recording sheet stored in the paper cassette, skew correction is performed by abutting the leading edge of the recording sheet against the registration roller pair, and at that time, a pair of alignments provided in the paper cassette are performed. By releasing the restriction of the recording sheet by the member, the recording sheet is rotated by the restoring force of the recording sheet, and the posture can be easily corrected. Therefore, the skew correction effect can be enhanced as compared with the related art.

(14) In the above embodiment, the tandem type color copying machine has been described as the image forming apparatus. However, the scope of application of the present invention is not limited to this, and other copying machines, printers, facsimile machines, and the like are used. Can be applied.
Further, the contents of the above-described embodiment and modification examples may be combined as much as possible.

  The present invention is useful as a technique for correcting sheet skew.

DESCRIPTION OF SYMBOLS 1 Copy machine 2 Printer part 3 Image reading part 30 Control part 40 Scanner unit 50 ADF unit 51 Pickup roller 52 Rolling part 53 Registration roller pair 54-56 Conveyance roller pair 61 Start button 70 Slide mechanism 71 Pinion 71a Rotating shaft 72a, 72b Rack Rod 73 Timing belt 502 Document feed tray 505a, 505b Alignment plate 521 Feed roller 522 Rolling roller N1 Rolling nip N2 Registration nip S14 Volume sensor

Claims (12)

After feeding the sheets one by one from the sheet bundle placed on the tray, the front end of the sheet is brought into contact with the nip portion of the registration roller pair in the rotation stopped state to form a loop, and skew correction is performed. A sheet conveying device that conveys a sheet by rotating
A pair of alignment members that regulate and align both ends of the sheet bundle placed on the tray in the sheet width direction orthogonal to the conveying direction;
Restriction release means for releasing restriction of the sheet bundle by the pair of alignment members;
After the sheet bundle is aligned by the pair of alignment members, the regulation of the sheet bundle by the pair of alignment members is released until the sheet fed from the sheet bundle is started to be conveyed by the pair of registration rollers. Control means for controlling the restriction release means as described above. Sheet size acquisition means for acquiring the sheet size of a sheet bundle placed on the tray,
The control means includes
When the length of the acquired sheet size in the sheet conveyance direction causes the leading edge of the sheet to abut the nip portion of the registration roller pair in the rotation stopped state, the trailing edge of the sheet is between the pair of alignment members. 2. The sheet conveying apparatus according to claim 1, wherein the restriction of the sheet bundle is released by controlling the restriction release unit only when the length is such that the sheet is positioned. Paper type information acquisition means for acquiring information on the paper type of the sheets constituting the sheet bundle,
The control means cancels the restriction when the thickness of the sheet is determined to be a predetermined value or more based on the information acquired by the paper type information acquisition means in addition to the length condition of the sheet size in the sheet conveyance direction. The sheet conveying apparatus according to claim 2, wherein the sheet bundle is deregulated by controlling a unit. Returning means for returning the pair of alignment members in a state in which the restriction to the sheet bundle is released to a state in which the sheet bundle is restricted and aligned is provided,
Each time the control means feeds a predetermined number of sheets from the sheet bundle,
After the predetermined number of sheets have been pulled out from between the pair of alignment members, the pair of alignment members remove the sheet bundle by controlling the return means until the next sheet is fed out. To restore regulation and alignment,
Thereafter, between the time when the next sheet is fed and the conveyance is started by the registration roller pair, the restriction release unit is controlled to release the restriction of the sheet bundle by the pair of alignment members. The sheet conveying apparatus according to any one of claims 1 to 3. The sheet conveying apparatus according to claim 4, wherein the predetermined number of sheets is set according to a sheet type of sheets constituting the sheet bundle. The sheet conveying apparatus according to claim 4, wherein the predetermined number is changed according to a remaining sheet amount of the sheet bundle. A start instruction receiving means for receiving a start instruction of a sheet conveying operation for feeding and conveying sheets one by one from the sheet bundle;
The timing for releasing the restriction of the sheet bundle by the pair of alignment members is after receiving a start instruction of a sheet conveying operation via the start instruction receiving unit. The sheet conveying apparatus according to 1.   The timing of releasing the regulation of the sheet bundle is after an instruction to start a sheet conveying operation is received via the start instruction receiving unit and an operation of feeding out a sheet from the sheet bundle is started. The sheet conveying apparatus according to 7. A mixed sheet receiving means for receiving an instruction from the user that the sheet bundle to be conveyed is mixed with sheets having different sheet widths;
When the control means receives that the sheets having different sheet widths are mixed via the mixed sheet receiving means, the timing for releasing the restriction of the sheet bundle by the pair of alignment members is the leading edge of the fed sheet. The sheet conveying apparatus according to any one of claims 1 to 8, wherein the restriction release unit is controlled so that the restriction release means comes after the roller is brought into contact with a nip portion of the registration roller pair in a rotation stopped state. Sheet size acquisition means for acquiring the sheet size of the sheet bundle placed on the tray;
A start instruction receiving means for receiving from the user a start instruction of a sheet transport operation for feeding and transporting sheets one by one from the sheet bundle;
The timing at which the restriction of the sheet bundle by the pair of alignment plates is released is before the start instruction of the sheet conveying operation is received via the start instruction receiving means and after the sheet size is acquired by the sheet size acquiring means. The sheet conveying apparatus according to claim 1, wherein: An image reading apparatus comprising the sheet conveying device according to claim 1. An image forming apparatus comprising the sheet conveying device according to claim 1.

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