JP6766588B2 - Image reader - Google Patents

Description

The present invention relates to an image reader. More specifically, the present invention relates to an image reading device including a background member that provides a background image of the original image when the original image is read by the reading means.

The image reading device irradiates the original with light, receives the light reflected by the image of the original, and reads the image. Some image reading devices are equipped with an automatic document transporting device such as an ADF (Auto Document Feeder). According to an image reading device equipped with an ADF, if a document is first set on the ADF, the image of the document can be automatically read by the image reading device while flowing a plurality of documents one by one.

In recent years, due to the improvement of global environment (eco) awareness, cost saving, or the spread of PCs (Personal Computers) and tablets, the materials to be stored are changed from printed matter to scan data to improve work efficiency. The number of companies is increasing. In this case, the scan data is created by reading the image of the printed matter with an image reading device.

The quality tends to differ between the case where the data is saved as printed matter and the case where the data is saved as scan data. That is, when the data is saved as a printed matter, the image is printed on different papers on each page, so that the tilt of the image on a specific page and the difference in magnification in the main scanning direction or the sub scanning direction between pages are observed. Even if they do occur, they are less noticeable and often acceptable. On the other hand, when the data is saved as scan data, each page of the scan data is displayed in order on the monitor by scrolling. For this reason, if there is a tilt of the image on a specific page or a difference in magnification in the main scanning direction or the sub-scanning direction between pages, they are easily noticeable and unacceptable.

The number of companies that store forms as electronic data is increasing, and there are also industries that handle amorphous paper, so the opportunities for companies to handle scan data are increasing. In addition, an increasing number of companies are improving business efficiency by cutting out images from scan data and performing OCR (Optical Character Recognition) processing.

Therefore, a technique for correcting an image of a document read by an image reader has been proposed. For example, the following Patent Documents 1 and 2 propose a technique for facilitating the detection of the vertices of an image of a document when correcting the image of the document.

Patent Document 1 below discloses a technique of using a background plate in which a portion straddling an edge of the paper is black and a central portion is white when reading a paper on which a patch for calibration is formed. By reading using this background plate, the edge of the paper can be detected on the scanned image from the density difference that occurs at the boundary between the edge of the paper and the black part of the background plate, and the patch part is the white background plate. It can be read against the background of the part.

Patent Document 2 below discloses an image reader and a document double-ended detection device including a black-and-white reference plate that is color-coded into white and black and can switch between a white part and a black part at the focal position of an image sensor. ing. This document both end detection device has a means for scanning the tip of the document with the black part and the white part of the black-and-white reference plate, respectively, and a means for detecting the change points of the first and second scan signals of the tip of the document with the black part. , The left edge of the document is determined by comparing the means for detecting the change points of the third and fourth scan signals in the white portion with the change points of the first scan signal and the change points of the third scan signal. It further includes means and means for comparing the change point of the second scan signal and the change point of the fourth scan signal and determining the right end of the document.

Japanese Unexamined Patent Publication No. 2014-116676 Japanese Unexamined Patent Publication No. 2003-219117

However, in the techniques of Patent Documents 1 and 2, there is no method for automatically removing the foreign matter when the foreign matter adheres to the original glass. When foreign matter adheres to the original glass, streak-like noise (image streak noise) may occur in the image of the portion passing through the portion where the foreign matter exists, which causes deterioration of the quality of the scanned image.

In addition, in the technique of Patent Document 1, when reading an irregularly sized document, it is necessary to rotate the facing plate in which the entire area in the main scanning direction is black in the direction opposite to the paper direction. As a result, the facing plate comes into contact with the conveyed document to increase the conveying resistance, resulting in deterioration of the quality of the scanned image.

Further, in the technique of Patent Document 2, when a thin paper document is read with a white background color, it becomes difficult to detect the vertices, and the accuracy of detecting the vertices is lowered. Further, when a thin paper document is read with the background color black, image fog, which is a phenomenon in which the white portion of the image of the document is transparent and the background color can be seen, occurs over the entire page. As a result, it is not possible to accurately perform magnification correction and keystone correction, resulting in deterioration of the quality of the scanned image.

The present invention is for solving the above problems, and an object of the present invention is to provide an image reading device capable of suppressing deterioration of the quality of a read image.

An image reading device according to one aspect of the present invention is a transporting means for transporting a document and a background of the original image and the document image through the scanning surface at a predetermined reading position along the transporting path of the document by the transporting means. comprising reading means for reading an image, and a background member provided at the reading position, the background member includes a first portion having a first density, and a second portion having a second density, third Each of the first and third densities is higher than the second densities, and the first, second, and third parts constitute the background image, including a third portion having a density of Then, by moving the background member along the transport direction of the document at the scanning position, the moving means for positioning each of the first portion, the second portion, the third portion, and the cleaning portion in order at the scanning position is provided. Further, the moving means positions the first portion, the second portion, and the third portion in order at the reading position at the timing when the document passes through the reading position, and the moving means positions the document in the reading position in order. By positioning the cleaning unit at the reading position at the timing when it is not in contact with the reading surface.

In the image reading device, preferably, the moving means rotates the background member in one direction about the rotation axis to rotate each of the first portion, the second portion, the third portion, and the cleaning portion. They are sequentially positioned at the scanning position, and one direction at the scanning position coincides with the transport direction of the document at the scanning position.

In the image reading device, preferably, the rotation speed of the background member is the same as the speed at which the document is conveyed by the conveying means.

In the above image reading device, preferably, the background member further includes a background portion having a semicircular shape when viewed in a cross section cut by a plane having a normal extending direction of the rotation axis, and the first portion. , The second portion, and the third portion are provided on the curved surface of the background portion, and the cleaning portion extends outward from a portion other than the curved surface of the background portion.

In the above image reading device, preferably, each of the first portion, the second portion, and the third portion rotates when viewed in a cross section cut by a plane having the extending direction of the rotation axis as a normal. It has a length such that the central angle around the axis is 60 degrees.

The image reading device preferably further includes a detecting means for detecting the document on the upstream side of the scanning position along the transport path of the document, and the moving means is first before the detecting means detects the front edge of the document. When the first time elapses after the detection means detects the front edge of the document, the moving means positions the second part at the reading position and the detection means rear of the document. When the second time elapses after detecting the edge, the moving means positions the third part at the reading position, and the second time is longer than the second time after the detecting means detects the rear edge of the document. When the time of 3 elapses, the moving means positions the cleaning unit at the reading position.

In the image reader, preferably, each of the first portion, the second portion, and the third portion has a uniform density along the main scanning direction.

In the image reading device, preferably, an extraction means for extracting an image of a document from an image read by the scanning means and a region in which the first portion or the third portion of the image of the document is a background image are defined as a document. The image is further provided with a correction means for correcting based on a region where the second portion of the image is a background image.

According to the present invention, it is possible to provide an image reading device capable of suppressing deterioration of the quality of the read image.

It is a figure which shows typically the appearance of the MFP 100 in one Embodiment of this invention. It is a block diagram which shows the functional structure of the MFP 100 in one Embodiment of this invention. It is sectional drawing which shows the schematic structure of the scanner part 30 in one Embodiment of this invention. It is sectional drawing which shows the structure of the facing member 50 in one Embodiment of this invention. It is a top view which shows the structure of the facing member 50 in one Embodiment of this invention. FIG. 1 is a first diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 2 is a second diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 3 is a third diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 4 is a fourth diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 5 is a fifth diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 6 is a sixth diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 7 is a seventh diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. FIG. 8 is a diagram schematically showing an operation when the MFP 100 reads an image on paper M in one embodiment of the present invention. It is a figure which shows typically the change of the position of the paper M along the transport path TP with the passage of time in one Embodiment of this invention. It is a figure which shows typically the image IM1 read by the reading part 30B in one Embodiment of this invention. It is a figure which shows typically the image IM2 extracted by the image processing unit 109 in one Embodiment of this invention.

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

In the following embodiment, a case where the image reader is an MFP will be described. The image reading device may be a scanner, a copying machine, or the like, as well as an MFP.

First, the configuration of the MFP 100 according to the present embodiment will be described.

FIG. 1 is a diagram schematically showing the appearance of the MFP 100 according to the embodiment of the present invention.

With reference to FIG. 1, the MFP 100 (an example of an image reading device) in the present embodiment mainly includes an MFP main body 10, an operation panel 20, and a scanner unit 30. The operation panel 20 is provided on the front surface of the MFP main body 10. The operation panel 20 displays various displays on the user and receives various operations from the user. The scanner unit 30 is provided on the upper part of the MFP main body 10.

FIG. 2 is a block diagram showing a functional configuration of the MFP 100 according to an embodiment of the present invention.

With reference to FIG. 2, the MFP 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an image reading unit 104, a network interface 105, and an operation panel. It includes a control unit 106, an auxiliary storage device 107, an image forming unit 108, and an image processing unit 109. The CPU 101, ROM 102, RAM 103, image reading unit 104, network interface 105, operation panel control unit 106, auxiliary storage device 107, image forming unit 108, and image processing unit 109 are each connected to each other by a bus or the like. There is.

The CPU 101 operates according to the control program and controls the entire MFP 100.

The ROM 102 stores the control program.

The RAM 103 is a working memory of the CPU 101, and temporarily stores various data.

The image reading unit 104 reads the image of the original by controlling the scanner unit 30. The image reading unit 104 includes a driving unit 104a (an example of a moving means). The drive unit 104a rotationally drives the opposing member 50, which will be described later. Further, the image reading unit 104 further includes a counter (not shown) for measuring time.

The network interface 105 transmits / receives information to / from an external device connected to the MFP 100 through a network (not shown).

The operation panel control unit 106 displays various information on the operation panel 20 and accepts various operations through the operation panel 20.

The auxiliary storage device 107 is, for example, an HDD (Hard Disk Drive), and stores various data such as image data read by the image reading unit 104.

The image forming unit 108 prints on paper inside the MFP main body 10. The image forming unit 108 is roughly composed of a toner image forming unit, a fixing device, a paper conveying unit, and the like. The image forming unit 108 forms an image on paper by, for example, an electrophotographic method. The toner image forming unit synthesizes four-color images by a so-called tandem method to form a color image on paper. 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 transport unit is composed of a paper feed roller, a transport roller, a motor for driving them, and the like. The paper transport unit feeds paper from the paper feed cassette and transports it inside the MFP main body 10. Further, the paper transport unit discharges the paper printed inside the MFP main body 10 to the outside of the MFP main body 10.

The image processing unit 109 corrects an image or the like read by the scanner unit 30.

FIG. 3 is a cross-sectional view showing the configuration of the scanner unit 30 according to the embodiment of the present invention. In the present specification, the main scanning direction of the reading unit 30B is the x-axis, the sub-scanning direction of the reading unit 30B is the y-axis, and the direction perpendicular to each of the main scanning direction and the sub-scanning direction of the reading unit 30B is z. It is defined as an axis.

With reference to FIG. 3, the scanner unit 30 includes a paper transport unit 30A (an example of a transport means) which is an ADF (Auto Document Sensor), a reading unit 30B (an example of a reading means), and an opposing member 50 (a background member). An example) and a sensor 60 (an example of a detection means) are included. When the user receives an image reading execution instruction from the user through the operation panel 20 with the paper M placed on the document mounting table 35a, the paper transport unit 30A transfers the paper M placed on the document mounting table 35a to the transport path. It is conveyed to the reading position (reading line of sight) RP along the TP, and then discharged to the paper ejection tray 35b. The arrow S indicates the transport direction of the paper M. The transport path TP is a path from the document placing table 35a to the paper output tray 35b inside the housing of the paper transport section 30A. The reading unit 30B reads the image of the paper M and the background image of the image of the paper M through the contact glass (original glass) 32 (an example of the reading surface) at the predetermined reading position RP along the transport path TP.

The paper transport unit 30A includes a document loading table 35a, a paper output tray 35b, a pickup roller 36, a paper feed roller 37a, a transport roller 37b and 37c, an upstream transport roller 37d, a downstream transport roller 37e, and the like. The transport roller 37f and the paper ejection roller 37g are included. Each of the pickup roller 36, the paper feed roller 37a, the transfer rollers 37b and 37c, the upstream transfer roller 37d, the downstream transfer roller 37e, the transfer roller 37f, and the paper discharge roller 37g is from the upstream side to the downstream side of the transfer path TP. The paper M is provided in this order, and the paper M is conveyed along the transfer path TP.

The pickup roller 36 and the paper feed roller 37a feed the paper M of the document mounting table 35a one by one. The transport rollers 37b and 37c and the upstream transport roller 37d immediately before the reading position RP transport the paper M to the reading position RP. Immediately after the reading position RP, the downstream transfer roller 37e and the transfer roller 37f convey the read paper M. The paper ejection roller 37g provided on the most downstream side of the transport path TP ejects the paper M onto the paper ejection tray 35b.

The reading unit 30B includes a contact glass 32, a light source 33a, an image sensor 33b, mirrors 34a, 34b, and 34c, and a lens 34d. The light source 33a emits light. The light emitted along the reading position RP is reflected by the surface of the paper M passing through the reading position RP (the lower surface in FIG. 2) and the facing member 50. The reflected light is further reflected by the mirrors 34a, 34b, and 34c, focused by the lens 34d, and incident on the image sensor 33b. The image sensor 33b reads an image of the surface of the paper M and a background image composed of the facing member 50 as image data. The image sensor 33b is made of, for example, a CCD (Charge-Coupled Device).

The facing member 50 constitutes a background image of the image of the paper M read by the reading unit 30B. The facing member 50 is provided at the reading position RP, and faces the contact glass 32 and the light source 33a with a transport path TP.

The sensor 60 detects the presence or absence of the paper M on the upstream side along the transport path TP from the reading position RP.

FIG. 4 is a cross-sectional view showing the configuration of the opposing member 50 according to the embodiment of the present invention. FIG. 4 shows the configuration of the opposing member 50 when viewed in a cross section cut by a plane having the extending direction of the rotation axis AX of the opposing member 50 as a normal. Note that in FIG. 4, for convenience of explanation, the contact glass 32 is also shown together with the facing member 50.

With reference to FIG. 4, the opposing member 50 is controlled by the drive unit 104a (FIG. 2) to rotate about the rotation axis AX in only one rotation direction indicated by the arrow K (that is, the opposing member 50 is an arrow. Does not rotate in the opposite direction of K). The rotation direction indicated by the arrow K in the reading position RP coincides with the transport direction indicated by the arrow S in the reading position RP. Further, the rotation speed of the facing member 50 is the same as the speed at which the paper transport unit 30A transports the document.

The facing member 50 includes a background portion 51 and a cleaning portion 52. The background portion 51 has a semi-cylindrical shape, which is a shape obtained when a cylinder is cut in half on a plane including the central axis. The background portion 51 has a semicircular shape when viewed in the cross section of FIG. The facing member 50 further includes a high concentration portion 61 (an example of the first portion), a low concentration portion 62 (an example of the second portion), and a high concentration portion 63 (an example of the third portion). There is. The high density unit 61, the low density unit 62, and the high density unit 63 constitute a background image of the image of the paper M read by the reading unit 30B. Each of the concentrations of the high concentration portions 61 and 63 is higher than the concentration of the low concentration portion 62. Each of the high density portion 61, the low density portion 62, and the high density portion 63 has a uniform density along the x-axis direction (main scanning direction). Typically, the high density parts 61 and 63 are black and the low density parts 62 are white.

Each of the high-concentration portion 61, the low-concentration portion 62, and the high-concentration portion 63 is provided in this order on the curved surface of the background portion 51 (the arc-shaped portion in FIG. 4) in the direction opposite to the arrow K. Each of the high-concentration portion 61, the low-concentration portion 62, and the high-concentration portion 63 has a length such that the central angles centered on the rotation axis AX are angles α1, α2, and α3, respectively. It is preferable that each of the angles α1, α2, and α3 is 60 degrees.

The high-density portion 61, the low-concentration portion 62, and the high-density portion 63 may be produced by a method of applying a required color to the background portion 51 made of resin, or a sheet material printed with the required color. , Double-sided tape or the like may be used to attach the background portion 51.

The cleaning unit 52 is a portion that cleans the contact glass 32 by removing foreign matter (paper dust and dirt) from the contact surface of the contact glass 32 with the paper M. The cleaning portion 52 extends outward from a portion of the background portion 51 other than the curved surface (a portion on the opposite side of the low concentration portion 62 with the rotation axis AX interposed therebetween). The cleaning unit 52 is made of a flexible material such as resin.

FIG. 5 is a plan view showing the configuration of the opposing member 50 according to the embodiment of the present invention. FIG. 5 shows the configuration of the opposing member 50 when viewed from the side opposite to the side where the contact glass 32 exists.

With reference to FIGS. 4 and 5, the opposing member 50 extends along the x-axis direction (main scanning direction). The width (length in the x-axis direction) W1 of the facing member 50 is larger than the width (maximum value of the width of the document that can be read by the reading unit 30B) W2 of the paper M. As a result, the facing member 50 constitutes a background image of the image of the paper M read by the reading unit 30B.

Subsequently, in the present embodiment, the operation when the MFP 100 reads the image of the paper M will be described.

The drive unit 104a moves (rotates) the opposing member 50 along the transport direction indicated by the arrow S at the reading position RP, thereby causing the high concentration unit 61, the low concentration unit 62, the high concentration unit 63, and the cleaning unit 52 to move (rotate). Each is sequentially positioned at the reading position RP. The drive unit 104a positions the high density unit 61, the low density unit 62, and the high density unit 63 in order at the reading position RP at the timing when the paper M passes through the reading position RP, and the paper M passes through the reading position RP. By positioning the cleaning unit 52 at the reading position RP at a timing when the cleaning unit 52 is not in contact with the contact glass 32.

6 to 13 are diagrams schematically showing an operation when the MFP 100 reads an image of paper M in one embodiment of the present invention. FIG. 14 is a diagram schematically showing a change in the position of the paper M along the transport path TP with the passage of time in one embodiment of the present invention.

With reference to FIG. 6, at time T = t0 before the sensor 60 detects the front edge of the paper M, the drive unit 104a positions the central position of the high density unit 61 in the circumferential direction at the reading position RP. This state is the initial state of the facing member 50, and the central position of the high concentration portion 61 in the circumferential direction is the initial position of the facing member 50. As a result, the background image near the tip of the paper M is composed of the high density portion 61.

With reference to FIGS. 7 and 14, at time T = t1 after time T = t0, when the front edge of the paper M reaches the detection position SP of the sensor 60 and the sensor 60 detects the front edge of the paper M ( When the sensor 60 is turned on), the drive unit 104a starts measuring (counting) the time at the counter.

With reference to FIGS. 8 and 14, at time T = t2 after time T = t1, the front edge of the paper M advances by a distance LH (mm) to reach the reading position RP, and the reading unit 30B reads the paper. Start reading the image of M. The distance LH (mm) is the distance from the detection position SP of the sensor 60 to the reading position RP.

Even if the reading unit 30B starts reading, the driving unit 104a still positions the central position of the high concentration unit 61 in the circumferential direction at the reading position RP, and the counter continues to measure the time.

With reference to FIGS. 9 and 14, at time T = t3, which is a time after time T = t2 and time TM1 (an example of the first time) has elapsed from time T = t1, the sensor 60 Finish measuring the time. The drive unit 104a rotates the opposing member 50 in the direction indicated by the arrow K to position the central position of the low concentration unit 62 in the circumferential direction at the reading position RP. As a result, the background image of the central portion of the paper M is composed of the low density portion 62.

The central position of the low concentration portion 62 in the circumferential direction is the first displacement position of the opposing member 50. The rotation angle of the opposing member 50 for moving from the initial position to the first displacement position is 60 degrees.

The time TM1 is the time from when the sensor 60 detects the front edge of the paper M until the position on the upstream side in the transport direction passes the reading position RP by a distance X (mm) from the tip of the paper M, and is the time from the reading unit 30B. Is calculated using the following equation (1), where the reading speed of is V (mm / s).

Time TM1 (s) = {distance LH (mm) + distance X (mm)} / reading speed V (mm / s) ... (1)

With reference to FIGS. 10 and 14, at time T = t4 after time T = t3, the rear end of the paper M reaches the detection position SP of the sensor 60, and the sensor 60 detects the rear end of the paper M. Then (when the sensor 60 is turned off), the drive unit 104a starts measuring the time at the counter.

With reference to FIGS. 11 and 14, at time T = t5 when time TM2 (an example of a second time) elapses from time T = t4, the drive unit 104a rotates the opposing member 50 in the direction indicated by the arrow K. The central position of the high-concentration portion 63 in the circumferential direction is positioned at the reading position RP. As a result, the background image near the rear edge of the paper M is composed of the high density portion 63. Even if the time TM2 elapses, the counter continues to measure the time.

The central position of the high concentration portion 63 in the circumferential direction is the second displacement position of the opposing member 50. The rotation angle of the opposing member 50 for moving from the first displacement position to the second displacement position is 60 degrees.

The time TM2 is the time from when the sensor 60 detects the rear end of the paper M until the position downstream of the rear end of the paper M by a distance Y (mm) passes through the reading position RP. When the reading speed of the unit 30B is the reading speed V (mm / s), the calculation is performed using the following formula (2). Typically, Y (mm) = X (mm).

Time TM2 (s) = {distance LH (mm) -distance Y (mm)} / reading speed V (mm / s) ... (2)

With reference to FIGS. 12 and 14, at time T = t6, which is a time after time T = t5 and time TM3 (an example of a third time, TM2 <TM3) has elapsed from time T = t4. , The sensor 60 finishes measuring the time. The drive unit 104a rotates the opposing member 50 by 240 degrees in the direction indicated by the arrow K, and positions the central position (initial position) of the high concentration unit 61 in the circumferential direction at the reading position RP.

With reference to FIGS. 13 and 14, at time T = t7 during rotation of the opposing member 50, the cleaning unit 52 passes through the reading position RP (the cleaning unit 52 is positioned at the reading position RP). The contact glass 32 comes into contact with the contact surface with the paper M. As a result, the contact surface of the contact glass 32 with the paper M is cleaned by the cleaning unit 52, and image streak noise caused by foreign matter can be suppressed.

The time TM3 is the time from when the sensor 60 detects the rear end of the paper M until the rear end of the paper M passes through the reading position RP, and the reading speed of the reading unit 30B is the reading speed V (mm / s). ), It is calculated using the following formula (3).

Time TM3 (s) = Distance LH (mm / reading speed V (mm / s) ... (3)

The image processing unit 109 (FIG. 2) performs the following processing on the image read by the reading unit 30B.

FIG. 15 is a diagram schematically showing an image IM1 read by the reading unit 30B in one embodiment of the present invention.

With reference to FIG. 15, the image IM1 read by the reading unit 30B includes the image IM2 of the paper M and the background image IM3. The image processing unit 109 extracts the image IM2 of the paper M from the image IM1.

The background image IM3 of the region RG1 on the front end side of the image IM1 is composed of the high density portion 61. Since the paper M has a low density (typically white), the contrast (difference between light and dark) between the background image IM3 and the image IM2 near the front edge is strong, and the vertices C1 and C2 on the front edge side of the paper M are in the image IM1. It appears clearly.

Similarly, the background image IM3 of the rear end side region RG3 in the image IM1 is composed of the high density portion 63. Since the paper M has a low density, the contrast between the background image IM3 and the image IM2 near the rear end is strong, and the vertices C3 and C4 on the rear end side of the paper M clearly appear in the image IM1.

As a result, the image processing unit 109 can extract the image IM2 of the paper M with an accurate boundary line based on the vertices C1, C2, C3, and C4. Further, the image processing unit 109 can perform tilt correction, magnification correction, keystone correction, and the like of the image based on the vertices C1, C2, C3, and C4.

The background image IM3 of the central region RG2 in the image IM1 is composed of the low density portion 62. Since the paper M has a low density, the contrast between the background image IM3 and the image IM2 in the central portion is weak, and when the paper M is thin paper, it is possible to prevent a situation in which image fog occurs in the image IM2 in the central portion. .. In particular, the image IM2 in the central portion is more likely to contain important information such as characters and images as compared with the image IM2 near the front end and the rear end. Is possible. Further, when the image processing unit 109 performs OCR processing on the image IM2 of the original, the density difference between the characters and the background is clear, so that the character discrimination accuracy can be improved.

Further, the image processing unit 109 makes the following corrections to the image IM2 (or the image IM1) as necessary.

FIG. 16 is a diagram schematically showing an image IM2 extracted by the image processing unit 109 in one embodiment of the present invention.

With reference to FIG. 16, the region RG1 in the image IM2 is a region in which the high density portion 61 is a background image, and the region RG3 in the image IM2 is a region in which the high density portion 63 is a background image. Therefore, when the paper M is thin paper, there is a high possibility that image fog ER will occur in the regions RG1 and RG3 in the image IM2. On the other hand, the region RG2 in the image IM2 is a region in which the low density portion 62 is a background image. Therefore, even when the paper M is thin paper, there is a low possibility that an image fog ER will occur in the region RG2 in the image IM2.

Therefore, the image processing unit 109 corrects the regions RG1 and RG3 in the image IM2 based on the region RG2 in the image IM2. As a result, image fog in the regions RG1 and RG3 in the image IM2 can be alleviated, and the quality of the image IM2 can be further improved.

[Effect of Embodiment]

According to the present embodiment, since the cleaning unit 52 removes the foreign matter adhering to the contact glass 32, it is possible to suppress the generation of image streak noise and the deterioration of the quality of the read image.

Further, since the opposing member 50 rotates along the conveying direction of the paper M, it is possible to avoid a situation in which the conveying resistance of the paper M increases due to the rotation of the opposing member 50, and it is possible to prevent deterioration of the quality of the scanned image. Can be done.

Further, since the contrast between the background image IM3 and the image IM2 near the front edge and the rear edge of the paper M is strong, the detection accuracy of the vertices C1, C2, C3, and C4 of the paper M can be improved. Further, since the background image IM3 in the central portion of the image IM2 is the low density portion 62, it is possible to minimize the occurrence of image fog when the paper M is thin paper. As a result, image processing such as image extraction, magnification correction, and keystone correction can be performed accurately, and deterioration of the quality of the scanned image can be suppressed.

Further, since the cleaning unit 52 cleans the contact glass 32 at the timing when the paper M does not pass through the reading position RP, it is possible to suppress a decrease in productivity due to the cleaning time.

[Other]

The facing member may have an arbitrary shape, and in addition to the shape of the above-described embodiment, the surface of the belt that rotates each of the first portion, the second portion, the third portion, and the cleaning portion. It may have the shape provided in.

The processing in the above-described embodiment may be performed by software or by using a hardware circuit. It is also possible to provide a program that executes the processing according to the above-described embodiment, and record the program on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card and provide the program to the user. You may decide to do it. The program is executed by a computer such as a CPU. Further, the program may be downloaded to the device via a communication line such as the Internet.

It should be considered that the above embodiments are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

10 MFP (Multifunction Peripheral) main unit 20 Operation panel 30 Scanner unit 30A Paper transfer unit (an example of transfer means)
30B reading unit (an example of reading means)
32 Contact glass 33a Light source 33b Image sensor 34a, 34b, 34c Mirror 34d Lens 35a Document mounting stand 35b Paper ejection tray 36 Pickup roller 37a Paper feed roller 37b, 37c, 37f Conveying roller 37d Upstream transport roller 37e Downstream transport roller 37g Discharge Paper roller 50 Opposing member 51 Background part 52 Cleaning part 60 Sensor (an example of detection means)
61, 63 High-density part 62 Low-density part 100 MFP (Example of image reader)
101 CPU (Central Processing Unit)
102 ROM (Read Only Memory)
103 RAM (Random Access Memory)
104 Image reading unit 104a Drive unit (example of moving means)
105 Network interface 106 Operation panel control unit 107 Auxiliary storage device 108 Image forming unit 109 Image processing unit AX Rotation axis C1, C2, C3, C4 Peak ER Image fog IM1 Scanned image IM2 Paper M image IM3 Background image LH Detection position SP Distance from to reading position RP M Paper RG1 Front end area in image IM1 RG2 Central area in image IM1 RG3 Rear end area in image IM1 RP Reading position SP Detection position TP Transport path

Claims (8)

Transport means for transporting documents and
A reading means for reading an image of the original and a background image of the image of the original through the reading surface at a predetermined reading position along the conveying path of the original by the conveying means.
And a background member provided at the reading position,
The background member includes a first portion having a first concentration, a second portion having a second concentration, a third portion having a third concentration, and a cleaning portion, and the first portion. And each of the third densities is higher than the second densities , and the first, second, and third portions constitute the background image.
By moving the background member along the transport direction of the document at the scanning position, the first portion, the second portion, the third portion, and the cleaning portion are read in order. With additional means of transportation to position
The moving means positions the first portion, the second portion, and the third portion in order at the reading position at the timing when the document passes the reading position.
The moving means is an image reading device that brings the cleaning unit into contact with the reading surface by positioning the cleaning unit at the reading position at a timing when the document does not pass through the reading position. By rotating the background member in one direction about the rotation axis, the moving means sequentially moves each of the first portion, the second portion, the third portion, and the cleaning portion. The image reading device according to claim 1, wherein the image reading device is positioned at the reading position, and the one direction at the reading position coincides with the transport direction of the document at the reading position. The image reading device according to claim 2, wherein the rotation speed of the background member is the same as the speed at which the document is conveyed by the conveying means. The background member further includes a background portion having a semicircular shape when viewed in a cross section cut by a plane having the extending direction of the rotation axis as a normal.
A claim that the first portion, the second portion, and the third portion are provided on the curved surface of the background portion, and the cleaning portion extends outward from a portion other than the curved surface of the background portion. Item 2. The image reading device according to item 2 or 3. Each of the first portion, the second portion, and the third portion is centered on the rotation axis when viewed in a cross section cut by a plane having the extending direction of the rotation axis as a normal. The image reading device according to claim 4, which has a length such that the central angle is 60 degrees. A detection means for detecting the document on the upstream side of the scanning position along the transport path of the document is further provided.
Before the detection means detects the front edge of the document, the moving means positions the first portion at the reading position.
When the first time elapses after the detection means detects the front edge of the document, the moving means positions the second portion at the reading position.
When the second time elapses after the detection means detects the rear end of the document, the moving means positions the third portion at the reading position.
2. The moving means positions the cleaning unit at the reading position when a third time longer than the second time elapses after the detection means detects the rear end of the document. The image reading device according to any one of. The image reading apparatus according to any one of claims 1 to 6, wherein each of the first portion, the second portion, and the third portion has a uniform density along the main scanning direction. An extraction means for extracting an image of the original from the image read by the reading means, and
The region where the first portion or the third portion of the original image is the background image is corrected based on the region where the second portion of the original image is the background image. The image reading device according to any one of claims 1 to 7, further comprising a correction means.

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