JP2018133693A - Document feeder and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document feeder and an image forming apparatus that are able to make an appropriate inclination correction in high speed reading of a large quantity of documents regardless of a document direction set by a user by allowing an amount of inclination before completion of image reading and reducing time required by a correction process.SOLUTION: The document feeder in which a reading position where an image of a document surface is read is provided on a document feed path and the document is fed along the document feed path, comprises: a control section; an end detecting section 57 disposed in the document feed path and that, as viewed along a feed direction of the document, detects an angle of a corner of a front end edge in the feed direction; and inclination detecting sections 55, 56 that detect an amount of inclination of the front end edge with respect to the feed direction. In a case where it is determined, on the basis of information obtained from the end detecting section 57, that the corner of the front end edge has a right angle, the control section determines, as an amount of inclination of the document, the amount of inclination of the front end edge obtained from the inclination detecting sections 55, 56, and makes an inclination correction to an image read at the reading position with the front end edge as a reference.SELECTED DRAWING: Figure 12

Description

  The present invention relates to an image forming apparatus for forming an image by an electrophotographic method and a document conveying device used therefor. Regardless of color or monochrome, the image forming apparatus includes a digital copying machine, a FAX, an electrophotographic apparatus such as a printer, a recording apparatus, a display apparatus, and the like.

  Japanese Patent Application Laid-Open No. 2012-085232 (Patent Document 1), Japanese Patent Application Laid-Open No. 2006-036065 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2015-170927 (Patent Document 3) each have an invention related to an image processing apparatus. It is disclosed.

  The image processing apparatus disclosed in Patent Document 1 employs a technique for determining the orientation of a character attribute partial image and rotating the character attribute partial image so that the orientation is correct when the orientation is incorrect.

  The reading device of Patent Document 2 extracts an edge of a document from image data, acquires the inclination α of the leading edge Et of the document and the inclination β of the trailing edge Eb of the document based on the extracted edge, and scans the scanner. If the difference between the inclination α and the inclination β is larger than the rotation skew threshold, it is determined that the rotation skew in which the inclination of the document changes as the document is conveyed occurs. After that, a technique is adopted in which the inclination of the leading edge and the inclination of the trailing edge are compared, and at least one of determination of the extraction range and determination of the rotation amount is executed based on the inclination with the smaller inclination angle. ing.

  The image reading apparatus disclosed in Patent Document 3 includes a document type and / or document determination unit, and selects an appropriate document tilt detection method by the determined document type and / or document determination unit. A document edge is selected by selecting a predetermined document edge as a document edge to be detected, and detecting the document inclination and / or document position with reference to the selected reliability edge. The technology to detect is disclosed.

JP2012-085232A Japanese Patent Laid-Open No. 2006-033605 Japanese Patent Laying-Open No. 2015-170927

  In the prior art, the inclination of the read image is corrected based on the edge portion at the leading edge of the document. However, if the user uses the cut edge of the original cut as the leading edge of the original, and the cut surface is oblique (non-parallel original at the leading and trailing edges), tilt correction is performed based on the oblique cut surface. As a result, the read image is inclined (cut original example).

  As disclosed in Patent Document 1, there is also a method of correcting the inclination with reference to characters in an image using an OCR (Optical Character Recognition Reader) function. However, the characters and the document do not always have the same inclination.

  In the technique described in Patent Document 2, the inclination of the edge including the angle and direction corresponding to the direction orthogonal to the document conveyance direction is detected. Premise paper is assumed as a premise. For example, when a book is used as a manuscript, the binding direction is different between vertical writing / horizontal writing of characters, and the cut surface is set at either the front end or the rear end in the transport direction. It is unknown. Furthermore, when the leading edge or the trailing edge is a cutting edge, if the inclination in the read image is a small inclination on the cutting edge side, the inclination is corrected based on the cutting edge.

  In the technique described in Patent Document 3, a document type and a document shape are detected from a scanned image, and an inclination correction method is selected based on the detection result. However, since the processing is started after all the images have been read once, the processing requires time, which is not suitable for high-speed reading of a large amount of documents.

  An object of the present invention has been made in view of the above problems, and determines whether a document set on a tray by a user is tilted by conveyance or whether an end portion (cut surface) of the document is slanted. An object of the present invention is to provide an original conveying apparatus and an image forming apparatus capable of performing appropriate inclination correction in high-speed reading of a large amount of originals regardless of a user's original setting direction.

  The document conveying device is a document conveying device having a reading position for reading an image on the surface of the document on the document conveying path, and conveying the document along the document conveying path. An edge detection unit that detects the angle of the front edge on the front side in the conveyance direction and the amount of inclination of the front edge with respect to the conveyance direction when viewed along the document conveyance direction. And the control unit obtains from the tilt detection unit when it is determined that the corner of the front end side has a right-angled part based on the information obtained from the end detection unit. The amount of inclination of the front edge is determined as the amount of inclination of the original, and the inclination of the image read at the reading position is corrected with the front edge as a reference.

  In another embodiment, when the control unit determines that the corner portion of the front end side does not have a right angle portion based on the information obtained from the end portion detection portion, the end portion detection portion causes the When viewed along the document conveyance direction, the angle of the rear edge of the rear side of the document in the conveyance direction is detected, and the inclination detection unit tilts the rear edge with respect to the conveyance direction. When the amount is detected and, based on the information obtained from the end detection unit, it is determined that the corner portion of the rear end side has a right angle portion, the inclination of the rear end side obtained from the inclination detection unit The amount is determined as the amount of inclination of the original, and the inclination of the image read at the reading position is corrected based on the trailing edge.

  In another form, when the control unit determines that there is no right-angled part at either the corner of the front edge or the corner of the rear edge of the document by the edge detection unit. Then, the conveyance of the original is stopped.

  In another embodiment, when an image on the back side of the original is read, image correction similar to the tilt correction performed on the front side is performed on the back side image.

  The image forming apparatus includes a document conveying device and an image forming unit that forms an image based on an image read by the document shipping device. The document shipping device is the document shipping device according to any one of the above. is there.

  According to the document conveying device and the image forming apparatus, it is determined whether the document set on the document tray by the user is inclined due to the conveyance or whether the document end (cut surface) is slanted, and is perpendicular to the document leading end. If it is determined, the amount of inclination is immediately determined based on the document leading edge. As a result, the amount of inclination can be determined before the image reading is completed, the time required for the correction process can be reduced, and appropriate inclination correction can be performed in high-speed reading of a large number of originals regardless of the original document setting direction.

1 is a perspective view illustrating a configuration of an image forming apparatus according to an embodiment. 1 is a block diagram illustrating a configuration of an image forming apparatus according to an embodiment. It is a figure which shows the internal structure of the scanner unit and ADF unit in embodiment. FIG. 6 is a diagram illustrating a left-bound document. FIG. 6 is a diagram illustrating a right-bound document. FIG. 4 is a diagram illustrating a document that is bound using staples. It is a figure which shows the case where the cut surface (cutting line) of an original is diagonal. FIG. 6 is a schematic diagram showing the arrangement positions of sensors with respect to a conveyance center line CL of a document to be conveyed. FIG. 5 is a diagram illustrating an arrangement relationship between a document to be conveyed and sensor positions. FIG. 4 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a case of a document having a vertical cut surface. FIG. 11 is a diagram schematically illustrating detection timings of an inclination sensor (R), an inclination sensor (F), and an edge detection sensor in the case of the document illustrated in FIG. 10. FIG. 4 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a document in which a rear cut surface is inclined. It is a figure which shows typically the detection timing in the inclination sensor (R), inclination sensor (F), and edge part detection sensor in the case of the original document shown in FIG. FIG. 6 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a case of a document having a front cut surface inclined. FIG. 15 is a diagram schematically illustrating detection timings of an inclination sensor (R), an inclination sensor (F), and an edge detection sensor in the case of the document illustrated in FIG. 14. FIG. 16 is a diagram illustrating an image inclination correction flow using the inclination sensor (R), the inclination sensor (F), and the edge detection sensor illustrated in FIGS. 12 to 15. FIG. 5 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a case where a document to be conveyed is inclined and a document having a vertical cut surface. FIG. 18 is a diagram schematically illustrating detection timings of an inclination sensor (R), an inclination sensor (F), and an edge detection sensor in the case of the document illustrated in FIG. 17. FIG. 4 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a document in which a document to be conveyed is inclined and a rear cut surface is inclined. FIG. 20 is a diagram schematically illustrating detection timings of an inclination sensor (R), an inclination sensor (F), and an edge detection sensor in the case of the document illustrated in FIG. 19. FIG. 4 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a case where a document to be conveyed is inclined and a document having a front cut surface is inclined. FIG. 22 is a diagram schematically illustrating detection timings of an inclination sensor (R), an inclination sensor (F), and an edge detection sensor in the case of the document illustrated in FIG. 21. It is a figure which shows the other arrangement | positioning form of an edge part detection sensor. It is a figure which shows other arrangement | positioning form of an edge part detection sensor. FIG. 5 is a schematic diagram illustrating a method for detecting a conveyance state of a document to be conveyed, and is a diagram illustrating a case of a document in which the uppermost cross section is inclined. FIG. 26 is a diagram schematically illustrating detection timings of an inclination sensor (R), an inclination sensor (F), and an edge detection sensor in the case of the document illustrated in FIG. 25.

  The image forming apparatus according to the present embodiment will be described below with reference to the drawings. In the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated. In the drawings, there are portions that are not illustrated in accordance with the ratios of actual dimensions, but are illustrated with the ratios changed so that the structures are clear in order to facilitate understanding of the structures.

  The image forming apparatus includes an MFP, a facsimile apparatus, or a copier having a scanner function, a copying function, a function as a printer, a facsimile function, a data communication function, and a server function. The document conveying device is an ADF unit provided in the image forming apparatus.

[Configuration of Image Forming Apparatus 1]
With reference to FIGS. 1 to 3, an image forming apparatus 1 in the present embodiment will be described. FIG. 1 is a perspective view illustrating the configuration of the image forming apparatus 1, FIG. 2 is a block diagram illustrating the configuration of the image forming apparatus 1, and FIG. 3 is a diagram illustrating the internal configuration of the scanner unit and the ADF unit.

  Referring to FIG. 1, an image forming apparatus 1 is an MFP (Multi Function Printer). The image forming apparatus 1 includes a control unit 10, an image forming unit 20, a paper feeding unit 30, a scanner unit 40, an ADF (Auto Document Feeder) unit 50 as a document conveying device, and an operation panel 60. The control unit 10, the image forming unit 20, and the paper feeding unit 30 are located at the center of the image forming apparatus 1. The scanner unit 40 and the ADF unit 50 are located on the upper part of the image forming apparatus 1. The operation panel 60 is located on the upper front surface of the image forming apparatus.

  Referring to FIG. 2, the control unit 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a communication I / F unit 14, and an image data storage. A unit 15 and a document size storage unit 16 are included. The CPU 11, the ROM 12, the RAM 13, the communication I / F unit 14, the image data storage unit 15, and the document size storage unit 16 are connected to each other.

  The CPU 11 controls the operation of the entire image forming apparatus 1. The ROM 12 stores a control program executed by the CPU 11. The RAM 13 is a working memory for the CPU 11. The communication I / F 14 transmits / receives various information to / from an external device (not shown) through a network or the like. The image data storage unit 15 stores image data read by the scanner unit 40 and the like. The document size storage unit 16 stores the size of the document measured by the ADF unit 50 and the size of the document set through the operation panel 60.

  The image forming unit 20 is roughly composed of a toner image forming unit and a fixing device. The image forming unit 20 forms an image on a sheet by, for example, electrophotography. The image forming unit 20 is configured to be able to form a color image on a sheet by synthesizing four color images by a so-called tandem method.

  The toner image forming unit includes a photoconductor provided for each color of C (cyan), M (magenta), Y (yellow), and K (black), and an intermediate in which a toner image is transferred (primary transfer) from the photoconductor. The image forming apparatus includes a transfer belt and a transfer unit that transfers an image from the intermediate transfer belt to a sheet (secondary transfer).

  The fixing device has a heating roller and a pressure roller. The fixing device conveys the sheet on which the toner image is formed between the heating roller and the pressure roller, and heats and presses the sheet. As a result, the fixing device melts the toner adhering to the paper and fixes it on the paper to form an image on the paper.

  The paper feed unit 30 includes a paper feed roller, a transport roller, and a motor that drives them. The paper feeding unit 30 feeds paper from a paper feeding cassette and conveys the paper inside the housing of the image forming apparatus 1. The paper feed unit 30 discharges the paper on which the image is formed from the image forming apparatus to a paper discharge tray or the like. The scanner unit 40 reads an image of a document and creates image data of the document.

  The ADF unit 50 sends a document (an example of a sheet) to the scanner unit 40 one by one. The ADF unit 50 includes a document transport motor 51, a back surface reading unit 52 provided in the case of simultaneous duplex scanning during document transport, a document size detection sensor 53, a document pre-read sensor 54, a tilt sensor (R) 55, and a tilt sensor (F). 56 and an end detection sensor 57. The document transport motor 51 operates under the control of the CPU 11.

  The document transport motor 51 includes an upstream roller drive motor and a downstream roller drive motor. The upstream roller drive motor drives the paper feed roller 154 (FIG. 3). The downstream roller drive motor drives the transport rollers 155, 156, 157, 158 and the paper discharge roller 159 (FIG. 3). The document size detection sensor 53 detects the size of the document placed on the document tray 151 (FIG. 3). As the pre-document reading sensor 54, an optical or mechanical sensor is used for the presence or absence of a document along the conveyance path.

  The detailed arrangement of the tilt sensor (R) 55, the tilt sensor (F) 56, and the end detection sensor 57 will be described later. As the tilt sensor (R) 55, the tilt sensor (F) 56, and the edge detection sensor 57, optical or mechanical sensors are used as in the pre-document reading sensor 54.

  More specifically, the inclination sensor (R) 55 and the inclination sensor (F) 56 detect the passage of the edge of the paper. Specifically, for example, one photoelectric sensor is used to detect the passage of the edge of the paper by blocking the light beam. The edge detection sensor 57 detects the shape of the corner of the paper. Specifically, photoelectric sensors arranged in a matrix are used to determine whether or not the corner of the sheet is a right angle based on the light blocking state.

  The operation panel 60 displays various information and accepts various operations. The operation panel 60 includes a start button 61 for starting various jobs such as a reading job and a copy job.

  Referring to FIG. 3, the ADF unit 50 is located above the scanner unit 40. The scanner unit 40 can read a document placed on the document table 141 and can also read a document sent from the ADF unit 50.

  The scanner unit 40 includes a document table 141, a light source 142, mirrors 143a, 143b, and 143c, and a CCD (Charge Coupled Device) 144. The light emitted from the light source 142 and reflected from the surface of the document is reflected by each of the mirrors 143a, 143b, and 143c and enters the CCD 144. As a result, the scanner unit 40 reads the document.

  The ADF unit 50 includes a document tray 151, a paper discharge tray 152, a pickup roller 153, a paper feed roller 154, transport rollers 155, 156, 157, 158, a paper discharge roller 159, and a CIS (Contact Image Sensor). 160. A document to be read is placed on the document tray 151. A document size detection sensor 53 that mechanically detects the document is provided on the upper surface of the document tray 151, and the size of the placed document is measured based on the detection result of the document size detection sensor 53. A document whose image has been read is discharged from the ADF unit 50 to the discharge tray 152.

  In the ADF unit 50, a transport path TR that connects the document tray 151 to the paper discharge tray 152 is provided. The pickup roller 153, the paper feed roller 154, the transport rollers 155, 156, 157, 158, and the paper discharge roller 159 are arranged in this order from the document tray 151 toward the paper discharge tray 152 along the transport path TR. Has been. A reading position RP is provided between the transport roller 156 and the transport roller 157. A CIS 160 is provided between the transport roller 157 and the transport roller 158.

  The ADF unit 50 sequentially supplies the originals placed on the original tray 151 one by one to the transport path TR by the pickup roller 153 and the paper feed roller 154. The ADF unit 50 performs registration correction on the document supplied to the transport path TR using the transport roller 155. The ADF unit 50 transports the document supplied to the transport path TR to the reading position RP along the transport path TR by the transport rollers 155 and 156.

  The scanner unit 40 reads the surface of the conveyed document at the reading position RP. Next, the ADF unit 50 transports the document whose surface has been read to the CIS 160 along the transport path TR by the transport roller 157. The scanner unit 40 reads the back side of the conveyed document by the CIS 160. Thereafter, the ADF unit 50 transports the document along the transport path TR to the discharge port by the transport roller 158 and discharges it onto the paper discharge tray 152 by the paper discharge roller 159.

(Original skew detection)
An inclination sensor (R) 55, an inclination sensor (F) 56, and an end detection sensor 57 are arranged in the transport path TR. Refer to the following figure for how to determine whether the document placed on the document tray by the user is tilted by conveyance or the document edge (cut surface) is slanted using this sensor and these sensors. To explain.

  With reference to FIG. 4 to FIG. 7, a document cutting mode will be described. 4 shows a left-bound document B1, FIG. 5 shows a right-bound document B2, FIG. 6 shows a document bound using staples, and FIG. 7 shows a cut surface (cutting line) of the document. ) Is a diagram showing a diagonal case.

  Normally, in the case of the left-bound document B1 shown in FIG. 4, the document is opened from the right side to the left side. The characters are written horizontally. In the case of the right-bound document B2 shown in FIG. 5, the document is opened from the left side to the right side. The characters are written vertically. As shown in FIG. 6, in the original using the staple ST, the staple ST portion is cut off. Referring to FIG. 7, a case where the cut surface (cutting line) S1 of the document P11 is oblique is shown.

  With reference to FIG. 8 and FIG. 9, each sensor position arranged in the transport path TR will be described. FIG. 8 is a schematic view showing the arrangement position of each sensor with respect to the conveyance center line CL of the conveyed document, and FIG. 9 is a diagram showing the arrangement relationship between the conveyed document and each sensor position.

  Referring to FIG. 8, the arrow in FIG. 8 is the document transport direction F1. FIG. 5 is a diagram showing the arrangement position of each sensor with respect to a conveyance center line CL of a conveyed document. In the case of the image forming apparatus 1 shown in FIG. 1, when viewed in the document transport direction F1 in the ADF unit 50, the left side is the back side of the apparatus and the right side is the front side of the apparatus in FIG.

  As shown in FIG. 8, a pre-document reading sensor 54 is disposed at a position shifted by S1 toward the front side of the apparatus with respect to the conveyance center line CL. The tilt sensor (R) 55 is disposed at a position shifted by S2 toward the back of the apparatus around the transport center line CL, and the tilt sensor (F) 56 is disposed at a position shifted by S3 toward the front of the apparatus.

  In the present embodiment, as an example, the pre-reading sensor 54 is disposed at a position of 6.0 mm as S1, and the tilt sensor (R) 55 and the tilt sensor (F) 56 are positioned at 87.0 mm as S2 and S3. Has been placed. Further, as shown in FIG. 9, an end detection sensor 57 is disposed in the vicinity of the tilt sensor (F) 56 on the front side of the apparatus.

  As for the arrangement of the inclination sensor (R) 55, the inclination sensor (F) 56, and the end detection sensor 57 in the ADF unit 50, as shown in FIG. 3, the inclination sensor (R) 55 and the inclination sensor ( F) 56 is arranged substantially on the same line as the pre-document reading sensor 54 in the direction orthogonal to the document conveyance direction F1. The edge detection sensor 57 is located downstream of the reading position RP on the downstream side of the inclination sensor (R) 55 and the inclination sensor (F) 56 when viewed along the document conveyance direction F1. Is arranged.

  As described above, the inclination sensor (R) 55 and the inclination sensor (F) 56 detect the passage of the edge of the paper. The edge detection sensor 57 detects the shape of the corner of the paper.

  With reference to FIGS. 10 to 16, a method for detecting the conveyance state of a document to be conveyed will be described. FIG. 10 shows the case of the original P10 having a vertical cut surface, and FIG. 11 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the edge detection sensor in the case of the original P10 shown in FIG. 5 is a diagram schematically showing detection timing at 57. FIG. In the case of the original P10, the original may be either right-bound or left-bound.

  FIG. 12 shows the case of the original P11 whose rear cut surface in the conveying direction is inclined. FIG. 13 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the like for the original P11 shown in FIG. And it is a figure which shows typically the detection timing in the edge part detection sensor 57. FIG. In the case of this document P11, a case of a right-bound document is usually considered.

  FIG. 14 shows the case of the original P12 whose front cut surface in the conveying direction is inclined. FIG. 15 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the original P12 shown in FIG. It is a figure which shows the detection timing in the edge part detection sensor 57. FIG. In the case of this document P12, the case of a left-bound document is usually considered.

  FIG. 16 is a diagram showing an image inclination correction flow using the inclination sensor (R) 55, the inclination sensor (F) 56, and the edge detection sensor 57 shown in FIGS.

  Referring to FIG. 10, FIG. 11, and FIG. 16, document P10 is conveyed (S10), and edge detection sensor 57 detects that the front corner C1 of document P11 is a right angle (S20, S30). . Next, the front end P11f and the rear end P11r of the document P11 sequentially pass through the tilt sensor (R) 55 and the tilt sensor (F) 56, so that the lengths of the widths W11 and W12 along the transport direction of the document P11. Are detected to be the same. Thereby, it is detected that the cut surface S1 of the document P10 is vertical, and the inclination amount of the front end P11f is detected (S40). Next, the inclination correction of the image read with reference to the front side of the document P10 is executed (S50). Specifically, in the case of the original P10, the image inclination correction is zero.

  Referring to FIGS. 12, 13 and 16, the document P11 is conveyed (S10), and the edge detection sensor 57 detects that the corner C1 on the front side of the document P11 is a right angle (S20, S30). . Next, the front end P11f and the rear end P11r of the document P11 sequentially pass through the tilt sensor (R) 55 and the tilt sensor (F) 56, so that the lengths of the widths W11 and W12 along the transport direction of the document P11. Are detected to be different.

  However, the front end P11f of the document P11 passes through the tilt sensor (R) 55 and the tilt sensor (F) 56 simultaneously. Thereby, it is detected that the cut surface S1 of the document P10 is vertical, and the inclination amount of the front end P11f is detected (S40). Next, the inclination correction of the image read with reference to the front side of the document P11 is executed (S50). Specifically, in the case of the original P11, the image inclination correction is zero.

  Referring to FIGS. 14, 15 and 16, document P12 is conveyed (S10), and edge detection sensor 57 detects that the front corner C1 of document P12 is not a right angle (S20, S30). Next, the front end P12f and the rear end P12r of the document P12 sequentially pass through the inclination sensor (R) 55 and the inclination sensor (F) 56, so that the lengths of the widths W11 and W12 along the conveyance direction of the document P12 are detected. Are detected to be different.

  However, the rear end P12r of the document P12 passes through the tilt sensor (R) 55 and the tilt sensor (F) 56 simultaneously. Further, the edge detection sensor 57 detects that the corner C2 on the rear side of the document P12 is a right angle (S60). As a result, it is determined that the cut surface S1 of the document P12 is not vertical, but the trailing edge P12r is vertical (S70). Next, the inclination correction of the image read with reference to the rear side of the document P12 is executed (S80). Specifically, in the case of this document P12, the image inclination correction is zero.

  If neither the front corner nor the rear corner of the original is a right angle, the conveyance of the original is stopped (S90).

  10 to 12 described the case where the sides of the documents P10, P11, and P12 on the back side of the apparatus and the side on the front side of the apparatus are parallel to the document transport direction. Next, with reference to FIGS. 17 to 22, a case where the side on the back side of the apparatus and the side on the front side of the apparatus are not parallel to the document conveyance direction will be described.

  FIG. 17 shows the case of the original P10 having a vertical cut surface, and FIG. 18 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the edge detection sensor in the case of the original P10 shown in FIG. 5 is a diagram schematically showing detection timing at 57. FIG. In the case of the original P10, the original may be either right-bound or left-bound.

  FIG. 19 shows the case of the original P11 whose rear cut surface in the conveying direction is inclined, and FIG. 20 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the like for the original P11 shown in FIG. And it is a figure which shows typically the detection timing in the edge part detection sensor 57. FIG. In the case of this document P11, a case of a right-bound document is usually considered.

  FIG. 21 shows the case of the original P12 whose front cut surface in the conveying direction is inclined. FIG. 22 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the original P12 shown in FIG. It is a figure which shows the detection timing in the edge part detection sensor 57. FIG. In the case of this document P12, the case of a left-bound document is usually considered.

  Referring to FIGS. 17, 18 and 16, the document P10 is conveyed (S10), and the edge detection sensor 57 detects that the corner C1 on the front side of the document P11 is a right angle (S20, S30). . Next, the front end P11f and the rear end P11r of the document P11 sequentially pass through the tilt sensor (R) 55 and the tilt sensor (F) 56, so that the lengths of the widths W11 and W12 along the transport direction of the document P11. Are detected to be the same.

  Thereby, it is detected that the cut surface S1 of the document P10 is vertical, and the inclination amount of the front end P11f is detected (S40). Next, the inclination correction of the image read with reference to the front side of the document P10 is executed (S50). Specifically, in the case of the original P10, the inclination of the image is obtained from the time difference between the inclination sensor (R) 55 and the front end P10f of the inclination sensor (F) 56.

  Referring to FIGS. 19, 20 and 16, the document P11 is conveyed (S10), and the edge detection sensor 57 detects that the corner C1 on the front side of the document P11 is a right angle (S20, S30). . Next, the front end P11f and the rear end P11r of the document P11 sequentially pass through the tilt sensor (R) 55 and the tilt sensor (F) 56, so that the lengths of the widths W11 and W12 along the transport direction of the document P11. Are detected to be different.

  However, since the front corner C1 of the document P11 is a right angle, it is detected that the cut surface S1 of the document P11 is vertical, and the inclination amount of the front end P11f is detected (S40). Next, the inclination correction of the image read with reference to the front side of the document P11 is executed (S50). Specifically, in the case of the original P11, the inclination of the image can be obtained from the time difference between the passage of the front end P11f of the inclination sensor (R) 55 and the inclination sensor (F) 56.

  Referring to FIGS. 21, 22 and 16, the document P12 is conveyed (S10), and the end detection sensor 57 detects that the front corner C1 of the document P12 is not a right angle (S20, S30). Next, it is detected that the rear corner C2 of the document P12 is a right angle (S60). Next, the front end P12f and the rear end P12r of the document P12 sequentially pass through the inclination sensor (R) 55 and the inclination sensor (F) 56, so that the lengths of the widths W11 and W12 along the conveyance direction of the document P12 are detected. Are detected to be different. However, the end detection sensor 57 detects that the rear corner C2 of the document P12 is a right angle (S60).

  As a result, it is determined that the cut surface S1 of the document P12 is not vertical, but the trailing edge P12r is vertical (S70). Next, the inclination correction of the image read with reference to the rear side of the document P12 is executed (S80). Specifically, in the case of the original P12, the inclination of the image can be obtained from a time difference between passage of the rear end P12f of the inclination sensor (R) 55 and the inclination sensor (F) 56.

  If neither the front corner nor the rear corner of the original is a right angle, the conveyance of the original is stopped (S90).

  As described above, in the image forming apparatus 1 according to the present embodiment, it is determined whether the document set on the tray by the user is tilted by conveyance or whether the document end (cut surface) is slanted. If the right angle is determined, the amount of inclination can be determined immediately before the image reading is completed by immediately determining the amount of inclination based on the document's leading edge, reducing the time required for correction processing and relating to the user's original setting direction. This makes it possible to correct the tilt properly when reading a large number of documents at high speed.

  In the image forming apparatus 1, the end detection sensor 57 is arranged on the front side of the apparatus. However, as shown in FIG. 23, the end detection sensor 57 is arranged on the back side of the apparatus. May be. Further, as shown in FIG. 24, the end detection sensor 57 may be arranged from the front side of the apparatus to the back side of the apparatus.

  In the above embodiment, the originals P10, P11, and P12 are described as having a cut surface on the front side or the rear side in the transport direction. However, as shown in FIGS. Similarly, even if the document P21 has a surface, it can be determined whether the document set by the user on the tray is tilted by conveyance or whether the document edge (cut surface) is slanted.

  Further, when the image forming apparatus 1 reads not only the image on the front side of the document but also the image on the back side, the image correction similar to the image correction performed on the front side also for the image on the back side. It is good to do.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 10 Control part, 12 ROM, 13 RAM, 14 Communication I / F part, 15 Image data storage part, 16 Original size storage part, 20 Image formation part, 30 Paper feed part, 40 Scanner unit, 50 unit , 51 Document transport motor, 52 means, 53 Document size detection sensor, 54 Front sensor, 57 Edge detection sensor, 60 Operation panel, 61 Start button, 141 Document table, 142 Light source, 143a Mirror, 151 Document tray, 152 Paper discharge Tray, 153 pickup roller, 154 paper feed roller, 155, 156, 157, 158 transport roller, 159 paper discharge roller.

Claims (5)

A document conveying device having a reading position for reading an image on the surface of a document on a document conveying path, and conveying a document along the document conveying path,
A control unit;
An end detection unit that is disposed in the original transport path and detects an angle of a front end side on the front side in the transport direction when viewed along the transport direction of the original;
An inclination detector that detects an amount of inclination of the front end side with respect to the transport direction, and
The controller is
Based on the information obtained from the end detection unit, when it is determined that the front end side has a right-angled portion,
The amount of inclination of the front edge obtained from the inclination detector is determined as the amount of inclination of the document, and the inclination of the image read at the reading position is corrected with respect to the front edge.
Document transport device. The controller is
Based on the information obtained from the end detection unit, when it is determined that there is no right-angle portion in the corner of the front end side,
The edge detection unit detects an angle of a rear edge of the rear side of the document in the conveyance direction when viewed along the document conveyance direction;
The inclination detection unit detects an inclination amount of the rear end side with respect to the conveyance direction,
Based on the information obtained from the edge detection unit, when it is determined that the corner of the rear edge has a right angle part, the amount of inclination of the rear edge obtained from the inclination detection unit is calculated. The document conveying apparatus according to claim 1, wherein the document conveying device is determined as an amount of inclination, and the inclination of an image read at the reading position is corrected with respect to the rear edge. The controller is
The conveyance of the document is stopped when the edge detection unit determines that there is no right-angled portion at either the corner of the front edge or the corner of the rear edge of the document. 2. The document conveying device according to 2.   4. The image correction according to claim 1, wherein when the image on the back side of the document is read, image correction similar to the tilt correction performed on the front side is performed on the image on the back side. Document transport device. A document feeder,
An image forming unit that forms an image based on an image read by the document sending device;
With
5. The image forming apparatus according to claim 1, wherein the document sending apparatus is the document sending apparatus according to claim 1.