JP6805867B2 - Document transfer device and image forming device - Google Patents

Description

The present invention relates to an image forming apparatus for forming an image by an electrophotographic method and a document transporting apparatus used therein. The image forming apparatus includes an electrophotographic apparatus such as a digital copier, a fax machine, and a printer, a recording apparatus, a display apparatus, and the like regardless of color or monochrome.

Japanese Patent Application Laid-Open No. 2012-0853232 (Patent Document 1), Japanese Patent Application Laid-Open No. 2016-0360665 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2015-170927 (Patent Document 3) have inventions relating to image processing devices, respectively. It is disclosed.

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

The scanning device of Patent Document 2 extracts the edge of the document from the image data, acquires the inclination α of the front edge Et of the document and the inclination β of the rear edge Eb of the document based on the extracted edge, and scans the scanner. Determines that when the difference between the inclination α and the inclination β is larger than the rotation skew threshold, the rotation skew in which the inclination of the document changes as the document is conveyed has occurred. After that, a technique is adopted in which the inclination of the front end side is compared with the inclination of the rear end side, and at least one of the determination of the extraction range and the determination of the rotation amount is executed based on the inclination of the smaller inclination angle. ing.

The image reading device of Patent Document 3 has a document type and / or a document discriminating means, and selects an appropriate document tilt detecting method by the discriminated document type and / or the document discriminating means. The original area is determined by selecting a reliable end, which is a predetermined original end, as a target for detecting the position of the original, and detecting the inclination and / or the position of the original with reference to the selected reliable end. The technology to detect is disclosed.

Japanese Unexamined Patent Publication No. 2012-085322 Japanese Unexamined Patent Publication No. 2016-036065 JP-A-2015-170927

In the prior art, the inclination of the scanned image is corrected based on the edge portion of the tip of the document. However, when the user uses the edge on the cut surface side of the original cut by himself as the tip of the document and the cut surface is diagonal (non-parallel original at the front and rear ends), the inclination is corrected based on the diagonal cut surface. The scanned image will be tilted (example of cut manuscript).

As disclosed in Patent Document 1, there is also a method of correcting the inclination based on the character in the image by using the OCR (Optical Character Recognition Reader) function. However, the inclinations of the characters and the original do not always match.

In the technique described in Patent Document 2, the inclination of the edge including the angle and the direction corresponding to the direction orthogonal to the document transport direction is detected. As a premise, standard paper is assumed. For example, when a book is used as a manuscript, the binding direction differs depending on whether the characters are written vertically or horizontally, and the cut surface is set at either the front end or the rear end in the transport direction. It is unknown. Further, when the front end or the rear end is a cutting end, if the inclination in the read image results in a small inclination on the cutting end side, the inclination is corrected based on the cutting end reference.

In the technique described in Patent Document 3, the original type and the original shape are detected from the scanned image, and the 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 number of documents.

An object of the present invention has been made in view of the above problems, and it is determined whether the document set by the user on the tray is tilted due to transportation or the edge of the document (cut surface) is slanted. Based on the results, it is an object of the present invention to provide a document transport device and an image forming device that enable appropriate tilt correction in high-speed scanning of a large number of documents regardless of the direction in which the user sets the documents.

This document transfer device has a reading position for reading an image of the surface of a document on the document transfer path, and is a document transfer device in which a document is transferred along the document transfer path, and is provided on a control unit and the document transfer path. When viewed along the transport direction of the document, the end detection unit that detects the angle of the corner of the front end side on the front side in the transport direction and the tilt amount of the front end side with respect to the transport direction are detected. When it is determined that the control unit has an angled portion at the corner of the front end side based on the information obtained from the end detection unit, the control unit includes the tilt detection unit. the inclination amount of obtained said front edge determines the inclination amount of the document, the front edge line of have the inclination correction of the image read by the reading position with respect to the, the information obtained from the edge detection unit Based on this, when it is determined that the corner portion of the front end side does not have a right angle portion, the end portion detecting portion is viewed along the transport direction of the document, and the rear side of the document in the transport direction. The angle of the corner of the rear end side is detected, the inclination detection unit detects the amount of inclination of the rear end side with respect to the transport direction, and the rear end side is based on the information obtained from the end detection unit. When it is determined that the corner portion has a right angle portion, the tilt amount of the rear end side obtained from the tilt detection unit is determined as the tilt amount of the document, and the reading is performed with reference to the rear end side. When the tilt of the image read at the position is corrected and the end detection unit determines that there is no right angle portion in either the front end side corner portion or the rear end side corner portion of the document. , Stop the transport of the document.

In another form, when the image on the back surface of the original document is read, the image on the back surface is also corrected in the same manner as the tilt correction performed on the front surface.

The image forming apparatus, obtain Preparations and document feeder according to any of the above, reads an image that has been conveyed the document feeder, on the basis of the read image, and an image forming unit for forming an image.

According to this document transport device and the image forming device, it is determined whether the document set by the user in the document tray is tilted due to the transfer or the document edge (cut surface) is slanted, and the document tip is at a right angle. If it is determined, the amount of tilt is immediately determined based on the tip of the document. As a result, the amount of tilt can be determined before the completion of image scanning, the time required for the correction process can be reduced, and appropriate tilt correction can be performed in high-speed scanning of a large number of documents regardless of the direction in which the user sets the document.

It is a perspective view which shows the structure of the image forming apparatus in embodiment. It is a block diagram which shows the structure of the image forming apparatus in embodiment. It is a figure which shows the internal structure of the scanner unit and ADF unit in embodiment. It is a figure which shows the manuscript of the left binding. It is a figure which shows the right-bound manuscript. It is a figure which shows the manuscript which was bound using the staple. It is a figure which shows the case where the cut surface (cutting line) of a document is slanted. It is the schematic which shows the arrangement position of each sensor with respect to the transfer center line CL of the document to be conveyed. It is a figure which shows the arrangement relationship between the transmitted document and each sensor position. It is a schematic diagram which shows the detection method of the conveyed state of the document to be conveyed, and is the figure which shows the case of the original which the cut surface is vertical. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG. It is a schematic diagram which shows the detection method of the transport state of the document to be conveyed, and is the figure which shows the case of the document which the cut surface on the rear side is inclined. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG. It is a schematic diagram which shows the detection method of the transport state of the document to be conveyed, and is the figure which shows the case of the document which the cut surface on the front side is inclined. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG. It is a figure which shows the tilt correction flow of the image using the tilt sensor (R), the tilt sensor (F), and the edge detection sensor shown in FIGS. 12 to 15. It is a schematic diagram which shows the detection method of the conveying state of the conveyed document, and is the figure which shows the case where the conveyed document is inclined, and the cut surface is a vertical document. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG. It is a schematic diagram which shows the detection method of the transport state of the document to be conveyed, and is the figure which shows the case of the document which is inclined, and the cut surface on the rear side is inclined. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG. It is a schematic diagram which shows the detection method of the transport state of the document to be conveyed, and is the figure which shows the case of the document which is inclined, and the cut surface on the front side is inclined. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG. It is a figure which shows the other arrangement form of the end detection sensor. It is a figure which shows the other arrangement form of the end detection sensor. It is a schematic diagram which shows the detection method of the transport state of the document to be conveyed, and is the figure which shows the case of the document which the outermost cross section of the upper end is inclined. It is a figure which shows typically the detection timing by the tilt sensor (R), the tilt sensor (F), and the edge detection sensor in the case of the document shown in FIG.

The image forming apparatus according to this embodiment will be described below with reference to the drawings. When referring to the number, quantity, etc. in the embodiments described below, the scope of the present invention is not necessarily limited to the number, quantity, etc., unless otherwise specified. The same parts and equivalent parts may be given the same reference number and duplicate explanations may not be repeated. In the drawings, some parts are not shown according to the actual dimensional ratio, and some parts are shown by changing the ratio so that the structure becomes clear in order to facilitate understanding of the structure.

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

[Structure of image forming apparatus 1]
The image forming apparatus 1 in the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view showing the configuration of the image forming apparatus 1, FIG. 2 is a block diagram showing the configuration of the image forming apparatus 1, and FIG. 3 is a diagram showing an internal configuration of a scanner unit and an ADF unit.

With reference to FIG. 1, the image forming apparatus 1 is an MFP (MultiFaction 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 transporting device, and an operation panel 60. The control unit 10, the image forming unit 20, and the paper feeding unit 30 are located in the central portion of the image forming apparatus 1. The scanner unit 40 and the ADF unit 50 are located above the image forming apparatus 1. The operation panel 60 is located on the upper front surface of the image forming apparatus.

With reference 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 image data storage. A unit 15 and a document size storage unit 16 are included. The CPU 11 and each of 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 of the CPU 11. The communication I / F 14 transmits and receives various types of information to and from an external device (not shown) via a network or the like. The image data storage unit 15 stores image data and the like read by the scanner unit 40. 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, a fixing device, and the like. The image forming unit 20 forms an image on paper by, for example, an electrophotographic method. The image forming unit 20 is configured to be capable of forming a color image on paper by synthesizing four-color images by a so-called tandem method.

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

The fixing device has a heating roller and a pressure roller. The fixing device conveys the paper on which the toner image is formed between the heating roller and the pressure roller while sandwiching the paper, and heats and pressurizes the paper. 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, a motor for driving them, and the like. The paper feed unit 30 feeds paper from the paper feed cassette and conveys it inside the housing of the image forming apparatus 1. The paper feeding unit 30 ejects the paper on which the image is formed from the image forming apparatus to a paper ejection tray or the like. The scanner unit 40 reads the image of the original and creates the image data of the original.

The ADF unit 50 sends a document (an example of a sheet) one by one to the scanner unit 40. The ADF unit 50 includes a document transfer motor 51, a back surface reading means 52 provided when both sides are simultaneously scanned during document transfer, a document size detection sensor 53, a document reading sensor 54, a tilt sensor (R) 55, and a tilt sensor (F). 56 and an end detection sensor 57 are included. 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 ejection 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 document reading sensor 54, an optical or mechanical sensor is used to determine the presence or absence of a document along the transport 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, an optical or mechanical sensor is used as in the pre-reading sensor 54.

More specifically, the tilt sensor (R) 55 and the tilt 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 light rays. The edge detection sensor 57 detects the shape of the corners of the paper. Specifically, using photoelectric sensors arranged in a matrix, it is determined whether or not the corners of the paper are at right angles 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 read job and a copy job.

With reference to FIG. 3, the ADF unit 50 is located above the scanner unit 40. The scanner unit 40 can read the originals arranged on the platen 141, and can also read the originals sent from the ADF unit 50.

The scanner unit 40 includes a platen 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 on the surface of the document is reflected by each of the mirrors 143a, 143b, and 143c and is incident on the CCD 144. As a result, the scanner unit 40 reads the original.

The ADF unit 50 includes a document tray 151, a paper output tray 152, a pickup roller 153, a paper feed roller 154, a transport roller 155, 156, 157, 158, a paper output roller 159, and a CIS (Contact Image Sensor). Includes 160 and. 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. The original image from which the image has been read is ejected from the ADF unit 50 to the output tray 152.

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

The ADF unit 50 sequentially supplies the documents placed on the document tray 151 to the transport path TR one by one by the pickup roller 153 and the paper feed roller 154. The ADF unit 50 performs resist correction on the original material supplied to the transport path TR by 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 original whose surface has been read to CIS160 along the transport path TR by the transport roller 157. The scanner unit 40 reads the back surface of the conveyed document by CIS160. After that, the ADF unit 50 transports the original document along the transport path TR to the discharge port by the transport roller 158, and discharges the document onto the paper output tray 152 by the paper output roller 159.

(Original tilt detection)
A tilt sensor (R) 55, a tilt sensor (F) 56, and an end detection sensor 57 are arranged on the transport path TR. Hereinafter, refer to the following figure for a method of determining whether the document set by the user in the document tray by the user is tilted due to transportation or the edge of the document (cut surface) is slanted using this arrangement and these sensors. I will explain.

The cutting form of the manuscript will be described with reference to FIGS. 4 to 7. FIG. 4 shows a left-bound manuscript B1, FIG. 5 shows a right-bound manuscript B2, FIG. 6 shows a manuscript bound using staples, and FIG. 7 shows a cut surface (cutting line) of the manuscript. It is a figure which shows the case where) is oblique.

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 a manuscript using staple ST, the staple ST portion is cut so as to be separated. With reference to FIG. 7, a case where the cut surface (cutting line) S1 of the document P11 is oblique is shown.

Each sensor position arranged in the transport path TR will be described with reference to FIGS. 8 and 9. FIG. 8 is a schematic view showing the arrangement position of each sensor with respect to the transfer 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.

With reference to FIG. 8, the arrow in FIG. 8 is the document transport direction F1. The figure which shows the arrangement position of each sensor with respect to the transport center line CL of the transport 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 device back side and the right side is the device front side in FIG.

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

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

Regarding the arrangement of the tilt sensor (R) 55, the tilt sensor (F) 56, and the end detection sensor 57 in the ADF unit 50, as shown in FIG. 3, the tilt sensor (R) 55 and the tilt sensor ( F) 56 is arranged on substantially the same line as the document reading sensor 54 in a direction orthogonal to the document transport direction F1. The edge detection sensor 57 is on the wake side of the tilt sensor (R) 55 and the tilt sensor (F) 56 when viewed along the document transport direction F1, and is on the upstream side of the reading position RP. Is located in.

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

A method of detecting the conveyed state of the conveyed document will be described with reference to FIGS. 10 to 16. FIG. 10 shows the case of the document P10 having a vertical cut surface, and FIG. 11 shows the tilt sensor (R) 55, the tilt sensor (F) 56, and the edge detection sensor in the case of the document P10 shown in FIG. It is a figure which shows typically the detection timing in 57. In the case of this document P10, either a right-binding or left-binding document may be used.

FIG. 12 shows the case of the original P11 having an inclined cut surface on the rear side in the transport direction, and FIG. 13 shows the tilt sensor (R) 55 and the tilt sensor (F) 56 in the case of the original P11 shown in FIG. It is a figure which shows typically the detection timing by the end detection sensor 57. In the case of this document P11, a right-bound document is usually considered.

FIG. 14 shows the case of the original P12 in which the cut surface on the front side in the transport direction is inclined, and FIG. 15 shows the inclination sensor (R) 55, the inclination sensor (F) 56, and the case of the original P12 shown in FIG. , Is a diagram showing the detection timing by the end detection sensor 57. In the case of this document P12, a left-bound document is usually considered.

FIG. 16 is a diagram showing a tilt correction flow of an image using the tilt sensor (R) 55, the tilt sensor (F) 56, and the end detection sensor 57 shown in FIGS. 12 to 15.

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

With reference to FIGS. 12, 13 and 16, the document P11 is conveyed (S10), and the end detection sensor 57 detects that the front corner C1 of the document P11 is at a right angle (S20, S30). .. Next, the front end P11f and the rear end P11r of the document P11 pass through the tilt sensor (R) 55 and the tilt sensor (F) 56 in sequence, so that the lengths of the widths W11 and W12 along the transport direction of the document P11 are long. Is 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 at the same time. As a result, it is detected that the cut surface S1 of the document P10 is vertical, and the amount of inclination of the front end P11f is detected (S40). Next, the tilt correction of the image read with reference to the front side of the document P11 is executed (S50). Specifically, in the case of this document P11, the tilt correction of the image is zero.

With reference to FIGS. 14, 15 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 at a right angle (S20, S30). Next, the front end P12f and the rear end P12r of the document P12 sequentially pass through the tilt sensor (R) 55 and the tilt sensor (F) 56, so that the widths W11 and W12 along the transport direction of the document P12 are long. Is 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 at the same time. Further, the edge detection sensor 57 detects that the rear corner C2 of the document P12 is at a right angle (S60). As a result, although the cut surface S1 of the document P12 is not vertical, it is determined that the rear end P12r is vertical (S70). Next, the tilt correction of the read image is executed with reference to the rear side of the document P12 (S80). Specifically, in the case of this document P12, the tilt correction of the image is zero.

If neither the front corner of the document nor the rear corner of the document is at a right angle, the transfer of the document is stopped (S90).

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

FIG. 17 shows the case of the document P10 having a vertical cut surface, and FIG. 18 shows the tilt sensor (R) 55, the tilt sensor (F) 56, and the edge detection sensor in the case of the document P10 shown in FIG. It is a figure which shows typically the detection timing in 57. In the case of this document P10, either a right-binding or left-binding document may be used.

FIG. 19 shows the case of the original P11 having an inclined cut surface on the rear side in the transport direction, and FIG. 20 shows the inclination sensor (R) 55 and the inclination sensor (F) 56 in the case of the original P11 shown in FIG. It is a figure which shows typically the detection timing by the end detection sensor 57. In the case of this document P11, a right-bound document is usually considered.

FIG. 21 shows the case of the document P12 in which the cut surface on the front side in the transport direction is inclined, and FIG. 22 shows the tilt sensor (R) 55, the tilt sensor (F) 56, and the tilt sensor (F) 56 in the case of the document P12 shown in FIG. , Is a diagram showing the detection timing by the end detection sensor 57. In the case of this document P12, a left-bound document is usually considered.

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

As a result, it is detected that the cut surface S1 of the document P10 is vertical, and the amount of inclination of the front end P11f is detected (S40). Next, the tilt 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 tilt of the image is obtained from the time difference between the tilt sensor (R) 55 and the front end P10f of the tilt sensor (F) 56.

With reference to FIGS. 19, 20 and 16, the document P11 is conveyed (S10), and the end detection sensor 57 detects that the front corner C1 of the document P11 is at a right angle (S20, S30). .. Next, the front end P11f and the rear end P11r of the document P11 pass through the tilt sensor (R) 55 and the tilt sensor (F) 56 in sequence, so that the lengths of the widths W11 and W12 along the transport direction of the document P11 are long. Is detected to be different.

However, since the front corner C1 of the document P11 is at a right angle, it is detected that the cut surface S1 of the document P11 is vertical, and the amount of inclination of the front end P11f is detected (S40). Next, the tilt 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 inclination sensor (R) 55 and the front end P11f of the inclination sensor (F) 56.

With reference 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 at a right angle (S20, S30). Next, it is detected that the corner portion C2 on the rear side 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 tilt sensor (R) 55 and the tilt sensor (F) 56, so that the widths W11 and W12 along the transport direction of the document P12 are long. Is detected to be different. However, the edge detection sensor 57 detects that the rear corner C2 of the document P12 is at a right angle (S60).

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

If neither the front corner of the document nor the rear corner of the document is at a right angle, the transfer of the document is stopped (S90).

In this way, in the image forming apparatus 1 of the present embodiment, it is determined whether the document set by the user on the tray is tilted due to transportation or the document end (cut surface) is slanted, and the document front end side is set. If it is determined to be a right angle, the amount of tilt can be determined immediately before the image reading is completed by immediately determining the amount of tilt based on the tip of the document, reducing the time required for correction processing and related to the user's document setting direction. It enables appropriate tilt correction in high-speed scanning of a large number of documents.

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

Further, in the above embodiment, the case where the documents P10, P11, and P12 have a cut surface on the front side or the rear side in the transport direction has been described, but as shown in FIGS. 25 and 26, the documents are cut on the back side of the device. 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 due to transportation or the edge of the document (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 on the back side is the same as the image correction performed on the front side. It is good to do.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the scope of claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims are included.

1 Image forming device, 10 Control unit, 12 ROM, 13 RAM, 14 Communication I / F unit, 15 Image data storage unit, 16 Original size storage unit, 20 Image forming unit, 30 Paper feeding unit, 40 Scanner unit, 50 units , 51 Document Conveyor Motor, 52 Means, 53 Document Size Detection Sensor, 54 Front Sensor, 57 Edge Detection Sensor, 60 Operation Panel, 61 Start Button, 141 Document Stand, 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 output roller.

Claims (3)

A document transfer device having a reading position for reading an image of a document surface on a document transfer path and transporting a document along the document transfer path.
Control unit and
An end detection unit that is arranged in the document transport path and detects the angle of the corner of the front end side on the front side in the transport direction when viewed along the transport direction of the document.
A tilt detection unit for detecting the tilt amount of the front end side with respect to the transport direction is provided.
The control unit
When it is determined that the corner portion of the front end side has a right-angled portion based on the information obtained from the end detection unit,
The inclined amount of inclination of the front side was obtained from the detection unit determines the inclination amount of the document, to have rows inclination correction of an image read by the reading position relative to the front edge,
When it is determined that the corner portion of the front end side does not have a right-angled portion based on the information obtained from the end detection unit,
When viewed along the transport direction of the document, the edge detection unit detects the angle of the corner of the rear end side of the document in the transport direction.
The tilt detection unit detects the amount of tilt of the rear end edge with respect to the transport direction,
When it is determined that the corner portion of the rear end side has a right-angled portion based on the information obtained from the end detection unit, the amount of inclination of the rear end side obtained from the inclination detection unit is used as the tilt amount of the document. The amount of tilt is determined, and the tilt of the image read at the reading position is corrected with reference to the rear end edge.
When the edge detection unit determines that there is no right-angled portion in either the corner portion of the front end side or the corner portion of the rear end side of the document , the document transfer is stopped. apparatus. The document transporting device according to claim 1, wherein when the image on the back surface of the document is read, the image on the back surface is also subjected to the same image correction as the tilt correction performed on the front surface. The document transporting apparatus according to claim 1 or 2 .
An image forming unit that reads an image conveyed by the document conveying device and forms an image based on the scanned image.
Bei El, the image forming apparatus.