JP5775828B2 - Image reading apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an image reading apparatus that reads a document. The present invention also relates to an image forming apparatus provided with the image reading apparatus.

  The image reading apparatus includes a light source that irradiates light on a document, an image sensor that receives reflected light from the document and performs photoelectric conversion, and outputs image data of the document. Some image reading apparatuses read a document passing (conveyed) on a contact glass. Here, dirt such as dust, glue, and ink may adhere to the contact glass. In addition, the contact glass may have scratches. If there is dirt or a flaw, the amount of light received by the light receiving element of the image sensor at the position corresponding to the dirt or flaw will decrease (the amount of light received will be smaller than normal when there is no dirt or flaw). As a result, dark streaks (black streaks) appear in the image data that are darker than surrounding pixels along the document transport direction (sub-scanning direction). A technique relating to such black stripe generation is described in Patent Document 1.

  Specifically, in Patent Document 1, in a document reading method that reads a document by feeding the document while the document reading unit is stopped at a specified document reading position, a predetermined sheet-through document is read at a timing before the document is read. A first step of stopping to read a document at a reading position, a second step of detecting an abnormal value of a read data value by performing reading main scanning, and an abnormal value not being detected in the second step If the abnormal value is detected in the third step of reading the document while the document reading unit is stopped and the second step, the stop position of the document reading unit is changed by a predetermined distance and image reading is started. And a fourth step of changing the timing by a predetermined count and returning to the second step. With this configuration, a sheet-through document reading apparatus and a document reading method that do not cause black streaks or the like on an image are provided (see Patent Document 1: Claim 1, paragraph [0008], etc.).

Japanese Patent No. 3577477

  The technique described in Patent Document 1 provides a sheet-through document reading apparatus and a document reading method that do not cause black streaks or the like on an image. However, the invention described in Patent Document 1 changes the stop position of the document reading means by a predetermined distance if there is an abnormality after reading the document (if a streak has occurred). Therefore, in some cases, a streak may occur on the first page from the start of document reading.

  Some image sensors include line sensors for a plurality of colors for color reading (for example, R, G, B). And since a fixed space | interval is provided between the line sensors of each color, the position of the line on the contact glass which each line sensor actually reads differs, respectively (a position has a difference in a subscanning direction). If even one of the colors is dirty or scratched on the reading line, the image data obtained by combining a plurality of colors and the printed material using the obtained image data are used in the document transport direction (sub-scanning direction). ) Along the lines. Therefore, particularly in the image sensor for color reading, there is a problem that black streaks may occur unless dirt or scratches are made on the reading lines of all color line sensors.

  In view of the above-described problems of the prior art, the present invention, when reading an original using an image sensor including line sensors for a plurality of colors, does not involve complicated operations or processing, and does not cause black streak from reading the first original. The problem is to eliminate the occurrence of

  In order to achieve the above object, an image reading apparatus according to claim 1 includes a document transport unit that transports a document toward a contact glass, a white plate provided so as to sandwich the contact glass and the document transported, An image sensor including a line sensor for at least three colors for color reading; and an optical unit that irradiates light along a main scanning direction toward the contact glass and the white plate, and guides reflected light to the image sensor; A moving unit that moves the optical unit in the sub-scanning direction, a generating unit that generates image data of each color based on the output of the image sensor, and an abnormal pixel that generates black streaks based on the image data A reference line that is a reference position of a reading line on the contact glass of each of the line sensors. Until the reading unit detects that the abnormal pixel is not present in the image data of each color based on the output of each line sensor for color reading. The optical unit is moved in order from the color close to the reference color so that the position of the reading line of the line sensor of the reference color which is the end color in the sub-scanning direction becomes the reference line position of the other color Each time the position of the reading line of the line sensor of the reference color is moved to the reference line position of another color by the moving process, the reading unit performs reading, and the detection unit It is detected whether or not the abnormal pixel is present in the image data of each color, and the position of the reading line of the line sensor of the reference color is determined in addition to the absence of the abnormal pixel in the image data of each color. In a state of being moved to the reference line position of the color, the document conveying unit conveys the document, the reading unit was set to be read of the original.

  According to this configuration, the moving unit is a reference that is an end color in the sub-scanning direction until the detecting unit detects that there is no abnormal pixel in the image data of each color based on the output of each line sensor for color reading. The position of the reading line of the color line sensor is moved in order from the color close to the reference color so that it becomes the reference line position of the other color. Each time the position of the reading line is moved to the reference line position of another color, the reading unit performs reading, and the detection unit includes all colors obtained by reading the line sensor that performs color reading in the image data of each color. The image data for each color is detected by detecting whether there is an abnormal pixel (in the image data for the minute) (whether there is an abnormal pixel in the image data of any color) In a state of being moved to the reference line positions of the other color abnormal pixel is not within over data, document conveying unit conveys the document, the reading unit reads the original. As a result, the document reading is executed after the line sensors for color reading are all free of dirt and scratches on the respective reading lines. Accordingly, it is possible to reduce the black stripe occurrence probability in the read image data of the document. Further, the moving process is performed before the document reading is started, and the position of the reading line of each color line sensor is shifted to a position free from dirt and scratches before the document reading is started. Can be eliminated. Also, by design, the reference line position is set so that the reading result is best (for example, less blur) in relation to accuracy and depth of field, and at least the reading line of the line sensor of the reference color Therefore, the original can be read in such a manner as to avoid deterioration in image quality of the original image data obtained by reading.

Further, in the invention of 請 Motomeko 1, so that the reader becomes the reference line position of the color adjacent to the reference color location of the reference color reading lines from the reference line position of the reference color moving The detection unit performs reading while the abnormal pixel is included in the image data of each color between the reference line position of the reference color and the reference line position of the color adjacent to the reference color. It is confirmed whether or not there is a non-detection reading line that is a non-existing line, and the abnormal pixel is included in the image data of each color even if the position of the reference color reading line is moved to the reference line position of any color. When there is, the moving unit moves the optical unit so that the position of the reference color reading line becomes the position of the non-detection reading line, and then the document conveying unit conveys the document, and the reading unit Scanning documents It was decided to carry out.

  According to this configuration, when there is an abnormal pixel in the image data of each color even if the position of the reference color reading line is moved to the reference line position of any color, the moving unit eliminates the position of the reference color reading line. After the optical unit is moved to the position of the detection reading line, the document conveying unit conveys the document, and the reading unit reads the document. As a result, although the positions of the reading lines for the respective colors deviate from the reference line position, the positions of the reading lines for all the colors can be adjusted to positions where there are no stains or scratches that cause black streaks in the image data. Therefore, it is possible to eliminate the occurrence of black streaks in the image data obtained by reading the original from the first original and the printed matter based on the image data.

According to a second aspect of the present invention, in the first aspect of the invention, the moving process is performed so that the position of the reference color reading line becomes the reference line position of a color that is not adjacent to the reference color. The reading unit performs reading, and the detection unit checks whether or not the non-detection reading line exists between the reference line position of the color before movement and the reference line position of the color after movement. Even if the position of the color reading line is moved to the reference line position of any color, the abnormal pixel exists in the image data of each color, and is adjacent to the reference color from the reference line position of the reference color When there is no non-detection reading line before the reference line position of a color, the moving unit becomes the position of the non-detection reading line confirmed between the reference line positions of colors other than the reference color. As the optical part After moved, the document conveying unit conveys the document, the reading unit was set to be read of the original.

  According to this configuration, even if the position of the reference color reading line is moved to the reference line position of any color, there is an abnormal pixel in the image data of each color, and the reference color is adjacent to the reference color from the reference line position of the reference color. When there is no non-detection reading line before the reference line position of the color to be changed, the optical unit is set so that the moving unit becomes the position of the non-detection reading line confirmed between the reference line positions of colors other than the reference color. After the movement, the document conveying unit conveys the document, and the reading unit reads the document. Thereby, although the moving distance of the reference color from the reference line position becomes relatively long, the position of the reading line for all colors can be adjusted to a position where there is no stain or flaw that causes black streaks in the image data. Therefore, it is possible to eliminate the occurrence of black streaks in the image data obtained by reading the original from the first original and the printed matter based on the image data.

In addition, the image sensor may be Mase including a line sensor for reading black-and-white. Further, even if the position of the reference color reading line is moved to the reference line position of any color, the abnormal pixel is present in the image data of each color, and the non-existence pixel is present between any of the reference line positions. When there is no detection reading line, the moving unit moves the optical unit so that the position of the reading line for the reference color becomes a predetermined reference line position for a line sensor for black and white reading, and then the original conveying unit conveys the document, the reading unit to read the original may be line Align.

  According to this configuration, the moving unit moves the optical unit so that the position of the reference color reading line becomes a predetermined reference line position for the black and white reading line sensor, and then the document conveying unit scans the document. The document is conveyed, and the reading unit reads the document. As a result, when the contact glass is stained or scratched in a fairly wide range, the position of the reading line of each image sensor can be set to a position where there is a low possibility that the stain or scratch is attached. In addition, as described above, the reference line position is set so that the reading result is the best by design, and the position of the reading line of the reference color line sensor is changed to the reference line position of the line sensor for black and white reading. Therefore, it is possible to read the document while avoiding deterioration in image quality of the image data of the document obtained by reading.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the moving unit sets the position of the reading line of each line sensor to the reference reading position where the reference line position becomes the reference line position before starting the reading of the document. The optical unit is moved, and the detection unit detects whether or not the abnormal pixel exists in the image data of each color obtained by the reading unit reading at the reference reading position, and When the abnormal pixel is present in the image data, the moving unit performs the moving process. When the abnormal pixel is not present in the image data of each color, the original conveying unit conveys the original in the state of the reference reading position. The reading unit reads a document.

  According to this configuration, the detection unit detects whether there is an abnormal pixel in the image data of each color obtained by the reading unit reading at the reference reading position, and the abnormal pixel is included in the image data of each color. If there is, the moving unit performs a moving process, and when there is no abnormal pixel in the image data of each color, the document conveying unit conveys the document in the state of the reference reading position, and the reading unit reads the document. As a result, the position of the reading line of each line sensor is set as the reference line position, and if no abnormal pixel is detected and black streak does not occur, the reading line position of each color is set to the ideal position. Reading can be done.

An image forming apparatus according to a fourth aspect includes the image reading apparatus according to any one of the first to third aspects.

  According to this configuration, since the original reading is performed after the reading lines of all the line sensors are free from dirt and scratches, printing can be performed based on the image data of the original without black streaks. In addition, black streaks are prevented from occurring on the first sheet of the document. Accordingly, it is possible to provide a high-quality image forming apparatus in which black streak does not occur in color reading.

  According to the present invention, even when an original is read in color by using an image sensor including line sensors for a plurality of colors, black streak is generated when the first original is read without complicated operations and processing. It is possible to provide an image reading apparatus that outputs image data having no black streak from the first document and an image forming apparatus that has no streak on the printed matter.

FIG. 2 is a front sectional view schematically showing a configuration of the multifunction machine. 1 is a schematic cross-sectional view illustrating an example of an image reading apparatus. 2 is a block diagram illustrating an example of a hardware configuration of a multifunction peripheral. FIG. It is a block diagram which shows an example of a structure of an image reading apparatus. It is explanatory drawing which shows an example of a structure of an image sensor. It is an enlarged explanatory view showing an example of the position of the reading line on the conveyance reading contact glass of each line sensor. 6 is a flowchart illustrating an example of a flow of black streak generation avoidance control before starting to read an original in color. 6 is a flowchart illustrating an example of a flow of black streak generation avoidance control before starting to read an original in color. It is an enlarged explanatory view showing an example of a state in which the position of the reading line of each line sensor is a reference line position. FIG. 6 is an enlarged explanatory diagram illustrating an example of a state in which a position of a reading line of a reference color line sensor is set to a reference line position of an adjacent color. FIG. 5 is an enlarged explanatory diagram illustrating an example of a state in which a position of a reading line of a reference color line sensor is set to a reference line position R of a color that is not adjacent. FIG. 6 is an enlarged explanatory diagram illustrating an example of a state in which a position of a reading line of a reference color line sensor is a reference line position of a line sensor for black and white reading. 6 is a flowchart illustrating an example of a control flow for storing presence / absence of abnormal pixels when reading a document in the monochrome mode. 6 is a flowchart illustrating an example of a flow of black stripe generation avoidance control at the time of starting document reading in the monochrome mode.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. However, each element such as configuration and arrangement described in this embodiment does not limit the scope of the invention and is merely an illustrative example.

(Outline of image forming apparatus)
First, an outline of an electrophotographic multifunction peripheral 200 (corresponding to an image forming apparatus) including the image reading apparatus 100 according to the embodiment will be described with reference to FIG. FIG. 1 is a front sectional view schematically showing the configuration of the multifunction machine 200.

  As shown in FIG. 1, the multifunction peripheral 200 according to the present embodiment has an image reading device 100 on the upper side. The image reading apparatus 100 irradiates light on the upper surface of the transport reading contact glass 11 (corresponding to the contact glass) or the placement reading contact glass 12, and reads the original by the image sensor 15 based on the reflected light to generate image data. An image reading unit 1 and a document conveying unit 2 that is provided above the image reading unit 1, opens and closes in the vertical direction with respect to the image reading unit 1, and conveys a document toward the conveyance reading contact glass 11. Details of the image reading apparatus 100 will be described later.

  Further, as indicated by a broken line in FIG. 1, an operation panel 3 is provided on the front side of the image reading unit 1. The operation panel 3 displays keys for setting the MFP 200, is a touch panel type, and includes a liquid crystal display unit 30 that accepts user input. Further, the liquid crystal display unit 30 can display the state of the multifunction device 200 such as an error such as a jam or out of paper. A numeric keypad 31 for inputting numbers such as the number of copies, a start key 32 for instructing copy execution, and the like are arranged on the operation panel 3.

  As shown in FIG. 1, the MFP 200 of the present embodiment includes a sheet feeding unit 4a, a conveyance unit 4b, an image forming unit 5a, an intermediate transfer unit 5b, a fixing unit 5c, and the like inside the main body. Each of the plurality of paper feeding units 4a accommodates a plurality of sheets of various sizes (for example, A-type and B-type paper such as A4 and B4) and various types of paper (for example, copy paper, recycled paper, cardboard, and OHP sheets). . Each paper feed unit 4a includes a paper feed roller 41 that is driven to rotate. At the time of printing, the paper feed roller 41 of one of the paper feed units 4a rotates to feed the paper to the transport unit 4b one by one.

  The transport unit 4b is a path for transporting paper within the apparatus. The transport unit 4b transports a guide plate for guiding the paper, a pair of transport rollers 42 that are rotationally driven when transporting the paper (a total of three from 42a, 42b, and 42c from the top in FIG. 1). A registration roller pair 43 or the like is provided that waits for the sheet to be printed in front of the image forming unit 5a and feeds the sheet in accordance with the transfer timing of the formed toner image. In addition, a pair of discharge rollers 45 for discharging the sheet after completion of fixing to the discharge tray 44 is also provided.

  The image forming section 5a includes a plurality of image forming units 50 (50Bk for black, 50Y for yellow, 50C for cyan, 50M for magenta) and an exposure device 51. The exposure device 51 outputs laser light while turning it on and off based on the image data read by the image reading unit 1, and scans and exposes each photosensitive drum. Each image forming unit 50 includes a photosensitive drum that is rotatably supported, and a charging device, a developing device, a cleaning device, and the like disposed around the photosensitive drum. Then, a toner image is formed on the peripheral surface of the photosensitive drum by each image forming unit 50 and the exposure device 51.

  The intermediate transfer unit 5b receives the primary transfer of the toner image from each image forming unit 50 and performs the secondary transfer onto the paper. The intermediate transfer unit 5b includes primary transfer rollers 52Bk to 52M, an intermediate transfer belt 53, a driving roller 54, a plurality of driven rollers 55a and 55b, a secondary transfer roller 56, a belt cleaning device 57, and the like. Each photosensitive drum corresponding to each primary transfer roller 52Bk to 52M sandwiches an endless intermediate transfer belt 53. A transfer voltage is applied to each of the primary transfer rollers 52 </ b> Bk to 52 </ b> M, and the toner image is transferred to the intermediate transfer belt 53.

  The intermediate transfer belt 53 is stretched around the driving roller 54 and the primary transfer rollers 52Bk to 52M. The intermediate transfer belt 53 circulates by rotation of a driving roller 54 connected to a driving mechanism (not shown) such as a motor. Further, the driving roller 54 and the secondary transfer roller 56 sandwich the intermediate transfer belt 53. The toner images (black, yellow, cyan, and magenta colors) formed by each image forming unit 50 are sequentially transferred to the intermediate transfer belt 53 in a superimposed manner without deviation, and then a predetermined voltage is applied 2 The image is transferred onto the sheet by the next transfer roller 56.

  The fixing unit 5c fixes the toner image transferred to the paper. The fixing unit 5c mainly includes a heating roller 58 containing a heating element and a pressure roller 59 in pressure contact therewith. When the paper passes through the nip between the heating roller 58 and the pressure roller 59, the toner is melted and heated, and the toner image is fixed on the paper. The sheet discharged from the fixing unit 5 c is sent to the discharge tray 44.

(Configuration of Image Reading Apparatus 100)
Next, an example of the image reading apparatus 100 according to the embodiment will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view showing an example of the image reading apparatus 100.

  First, the document conveying unit 2 automatically and continuously conveys documents to be read one by one to the conveyance reading contact glass 11. The document transport unit 2 includes, in order from the upstream side in the document transport direction, a document tray 21, a document supply roller 22, a document transport path 23, a plurality of document transport roller pairs 24, a document discharge roller pair 25, a document discharge tray 26, and the like. Further, the document conveying unit 2 is attached to the image reading unit 1 so as to be able to be opened and closed in the vertical direction with the back side of the sheet of FIG. 2 as a fulcrum, and functions as a cover for pressing each contact glass of the image reading unit 1 from above.

  A white plate 27 is provided on the upper surface of the conveyance reading contact glass 11. The document is conveyed while passing between the conveyance reading contact glass 11 and the white plate 27. In other words, the white plate 27 functions as a guide for document conveyance. When reading is performed when the document is not conveyed, the image sensor 15 reads the white plate 27.

  A plurality of documents to be read are placed on the document tray 21. Then, the document supply roller 22 contacts the uppermost document among the documents placed on the document tray 21. For example, when an input to read a document is input to the multi-function device 200, such as when the start key 32 is pressed, the document supply roller 22 sends the document to the document transport path 23 one by one.

  The document fed from the document tray 21 is guided to a plurality of document transport roller pairs 24 and guides, and passes through the upper surface of the transport reading contact glass 11 provided on the upper surface of the image reading unit 1. During this passage, the image reading unit 1 performs reading. Then, the document that has been read is discharged from the document discharge roller pair 25 to the document discharge tray 26 (the document transport path is indicated by a two-dot chain line). Each of the rotating bodies (the document supply roller 22, the document transport roller pair 24, and the document discharge roller pair 25) rotates using the document transport motor 28 (see FIG. 4) as a drive source.

  Next, the image reading unit 1 in the present embodiment will be described. As shown in FIGS. 1 and 2, the image reading unit 1 has a box-shaped housing. Then, on the left side of the upper surface of the image reading unit 1, a transparent plate-shaped conveyance reading contact glass 11 is arranged with the main scanning direction (direction perpendicular to the paper surface of FIG. 2) as the longitudinal direction. A transparent plate-like placement reading contact glass 12 is arranged on the upper surface of the image reading unit 1 on the right side of the conveyance reading contact glass 11. When reading a document such as a book one by one, the user lifts the document transport unit 2 and places the document on the placement reading contact glass 12 with the reading surface facing downward.

  Further, as shown in FIG. 2, a first moving frame 61 (equivalent to an optical unit and a reading unit), a second moving frame 62 (equivalent to an optical unit and a reading unit), and a wire 63 are provided in the housing of the image reading unit 1. (Corresponding to the moving part), the winding drum 64 (corresponding to the moving part), the lens 14 (corresponding to the reading part), and the light irradiated to the original are incident, and the original is read line by line to generate image data. For example, an image sensor 15 (corresponding to a reading unit) is arranged. The first moving frame 61, the second moving frame 62, the lens 14, the image sensor 15 and the like serve as a reading unit that reads a document.

  The first moving frame 61 supports a light source 610 (corresponding to an optical unit and a reading unit) that irradiates light on a document along the main scanning direction and a first mirror 611 (corresponding to an optical unit and a reading unit) below. As the light source 610, an LED lamp or a lamp using a fluorescent tube (for example, a cold cathode tube) can be used, and the type of the lamp is not particularly limited. The second moving frame 62 supports a second mirror 622 (corresponding to an optical unit and a reading unit) on the upper side and a third mirror 623 (corresponding to an optical unit and a reading unit) on the lower side. Further, the first moving frame 61 is disposed above the second moving frame 62. The light source 610, the first mirror 611, the second mirror 622, and the third mirror 623 have shapes extending in the main scanning direction (the direction perpendicular to the paper surface of FIG. 2).

  A plurality of wires 63 are attached to the first moving frame 61 and the second moving frame 62 (in FIG. 2, only one wire 63 is shown for convenience). The other end of the wire 63 is connected to the winding drum 64. The winding drum 64 is driven by a winding motor 65 (corresponding to a moving unit, see FIG. 4). By the forward / reverse rotation of the winding motor 65, the winding drum 64 rotates forward / reversely. Thereby, the 1st moving frame 61 and the 2nd moving frame 62 can be freely moved to a horizontal direction. In order to reduce the difference in the optical path length from the light source 610 to the image sensor 15 due to the position of each moving frame (the first moving frame 61 and the second moving frame 62), a plurality of pulleys (not shown) are provided inside the image reading unit 1. ) Is provided. And the tension of the wire 63 and the wiring of the wire 63 with respect to the pulley are different between the first moving frame 61 and the second moving frame 62. For example, if the moving distance of the first moving frame 61 is 1, the second movement The moving distance of the frame 62 is 0.5 (the first moving frame 61 is moved faster).

  The light emitted from the light source 610 hits the document on the conveyance reading contact glass 11 and is reflected. The first mirror 611, the second mirror 622, and the third mirror 623 guide the reflected light to the lens 14 while reflecting. The lens 14 collects the reflected light and enters the image sensor 15. For example, the image sensor 15 includes a line sensor 7 in which a plurality of light receiving elements 70 (photoelectric conversion elements) are arranged in a line (details will be described later).

  Then, each light receiving element 70 (each pixel) of the image sensor 15 converts it into an analog electric signal according to the level of reflected light (light reception amount). Reading is performed line by line in the main scanning direction (direction perpendicular to the document conveying direction) of the document, and reading of each line is continuously repeated in the sub-scanning direction (document conveying direction) to read one document. It is done.

  Here, an example of a specific document reading operation will be described. First, when reading a document conveyed by the document conveying unit 2, the take-up motor 65 is driven, and the first moving frame 61 and the second moving frame 62 are fixed at positions below the conveying / reading contact glass 11. Then, the light source 610 emits light to the passing document. On the other hand, when reading a document placed on the placement reading contact glass 12, the first moving frame 61 and the second moving frame 62 are moved to the home position by the winding drum 64, the wire 63, or the like while the light source 610 is turned on. To the right in FIG. Then, the scanning operation by the image sensor 15 is sequentially performed sequentially from the beginning to the rear end of the document, whereby the entire document is read and the document image is converted into an electrical signal.

(Hardware configuration of MFP 200)
Next, an example of the hardware configuration of the multifunction machine 200 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram illustrating an example of a hardware configuration of the multifunction device 200.

  First, the multifunction device 200 is provided with a main control unit 201 that controls the entire multifunction device 200. The main control unit 201 is provided with a CPU 202 as a central processing unit. In addition, a storage device 203 composed of nonvolatile and volatile memories such as RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), and Flash ROM is provided in the main control unit 201 (main control unit). 201 may be provided outside.

  The storage device 203 stores a program, data, and the like for controlling the multifunction device 200. The main control unit 201 uses the program and data stored in the storage device 203 to control each unit and perform printing. The main control unit 201 is a main control unit that performs overall control, communication control, and image processing, and an engine control unit that controls ON / OFF of a toner image formation control, a motor that rotates various rotating bodies, and the like to control printing. For example, a plurality of types may be provided for each function.

  The main control unit 201 is provided with an image processing unit 204 that performs image processing based on the image data output from the image reading apparatus 100. For example, the image processing unit 204 includes an ASIC, an image memory, and the like, and can perform various types of image processing such as density conversion processing, enlargement / reduction processing, rotation processing, and image data compression / expansion processing. Note that the image processing unit 204 can perform other image processing (for example, frame removal processing) and the like, but will not be described as being able to perform known image processing.

  The main control unit 201 is connected to the sheet feeding unit 4a, the conveyance unit 4b, the image forming unit 5a, the intermediate transfer unit 5b, the fixing unit 5c, the operation panel 3, and the like. The main control unit 201 controls the operation of each unit such as paper conveyance and toner image formation. Also, settings on the operation panel 3 and copy execution instructions are transmitted to the main control unit 201. The main control unit 201 is also connected to the image reading apparatus 100. For example, when executing copying, the main control unit 201 gives an operation instruction to the image reading apparatus 100, receives image data of a document from the image reading unit 1, and forms a toner image on the image forming unit 5a based on the image data ( (Print).

  The multifunction device 200 includes a communication unit 205 as a communication interface with the outside. For example, the communication unit 205 communicates with an external computer 300 (for example, a personal computer or a server) or the FAX apparatus 400 via a network, a cable, or a public line. For example, the communication unit 205 includes a plurality of connectors for connecting to a network, a cable, and a public line, and communication circuits such as a communication control controller, a chip, and a modem. With this communication unit 205, the multi-function device 200 can receive print data including image data and print setting data from the computer 300 or the like and perform printing (printer function). Further, image data obtained by reading an original with the image reading unit 1 can be transmitted to an external computer 300 or a FAX apparatus 400 (scanning and transmission function).

(Hardware configuration of image reading apparatus 100)
Next, an example of the hardware configuration of the image reading apparatus 100 according to the embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram illustrating an example of the configuration of the image reading apparatus 100. FIG. 5 is an explanatory diagram showing an example of the configuration of the image sensor 15.

  As described above, the image reading apparatus 100 according to the present embodiment includes the document conveying unit 2 and the image reading unit 1. First, the document conveying unit 2 will be described.

  Since the document transport unit 2 uses a copy function and a transmission function, when reading a document, the document placed on the document tray 21 is directed to the transport reading contact glass 11 one by one continuously and automatically. Transport. The document feeder 2 may be called an ADF (Auto Document Feeder).

  The document transport unit 2 is provided with a document transport control unit 20 that controls the operation of the document transport unit 2. The document conveyance control unit 20 is communicably connected to the main control unit 201 and the reading control unit 10 described above. For example, the document conveyance control unit 20 is a substrate including a CPU as a central processing unit, a ROM and a RAM for storing control programs and data. The document conveyance control unit 20 communicates with the main control unit 201 and the like, and receives an instruction to start document conveyance from the main control unit 201 and the reading control unit 10 and controls the operation of the document conveyance unit 2. For example, when a document reading instruction is issued from the main control unit 201, the document transport motor 28 is driven to rotate the document supply roller 22, the document transport roller pair 24, and the like.

  Next, the image reading unit 1 will be described. First, the image reading unit 1 is provided with a reading control unit 10 that controls the operation of the image reading unit 1. The reading control unit 10 is communicably connected to the main control unit 201 and the document conveyance control unit 20 described above. The reading control unit 10 receives an instruction and signal from the main control unit 201 and reads the document. The reading control unit 10 is a substrate including a CPU and an ASIC as a processing apparatus.

  The reading control unit 10 is communicably connected to a storage unit 16 including a ROM and a RAM that store programs and data necessary for controlling the image reading apparatus 100. The storage unit 16 may be mounted on the reading control unit 10.

  For example, when the start key 32 of the operation panel 3 is pressed, the copy function and the transmission function are used. Therefore, when reading a document, the reading control unit 10 receives an instruction from the main control unit 201 and reads the image. Operation control of each member in the unit 1 and transmission control of image data obtained by reading to the main control unit 201 are performed.

  The reading control unit 10 is connected to a winding motor 65. Thereby, the rotation of the winding motor 65 is controlled, the winding drum 64 is rotated, and the respective moving frames (the first moving frame 61 and the second moving frame 62) are moved in the horizontal direction. For example, the winding motor 65 is a pulse motor.

  Then, the reading control unit 10 inputs a pulse for moving each moving frame to the winding motor 65. As a result, the take-up motor 65 rotates by the number of pulses received from the reading control unit 10, and each moving frame moves. In other words, the reading control unit 10 controls the rotation of the take-up motor 65 to control the movement of each moving frame in the sub-scanning direction.

  The reading control unit 10 can move each moving frame in units of the width of one line in the sub-scanning direction when reading by the image sensor 15 (for example, in the case of 600 dpi, the unit is 42.3 μm). In other words, the distance (resolution) by which each moving frame moves by one pulse is at least 1 / integer of the reading width of the image sensor 15 in the sub-scanning direction. As a result, the position of the reading line 8 of the image sensor 15 in the conveyance reading contact glass 11 can be shifted by one pixel unit (one line unit).

  The reading control unit 10 is connected to a lighting circuit 612 that turns on the light source 610, the image sensor 15, the A / D conversion unit 17 (corresponding to the generation unit), the correction processing unit 18, and the like. In response, an instruction to read the document, in other words, an instruction to drive is given.

  The lighting circuit 612 is a circuit for lighting the light source 610. For example, when the light source 610 is an LED, the lighting circuit 612 is a circuit that causes a direct current to flow through the LED. When the light source 610 is a fluorescent tube (for example, a cold cathode tube), for example, the lighting circuit 612 is an inverter. Then, the reading control unit 10 causes the lighting circuit 612 to light the light source 610 based on an instruction to start reading from the main control unit 201.

  The image sensor 15 receives the light applied to the document and outputs four types of analog electrical signals of R (Red), G (Green), B (Blue), and Bk (Black / White) for each pixel. The magnitude of the electrical signal of each pixel varies depending on the amount of received light.

  Here, the configuration of the image sensor 15 according to the present embodiment will be described with reference to FIG. For example, the image sensor 15 of the present embodiment can read at 600 dpi. As shown in FIG. 5, the image sensor 15 is provided with four line sensors 7 extending in the main scanning direction (the front-rear direction of the multifunction device 200 and the direction perpendicular to the document conveyance direction).

  For example, as shown in FIG. 4, each line sensor 7 is provided in the order of a line sensor 7Bk (for monochrome reading), a line sensor 7B (blue), a line sensor 7G (green), and a line sensor 7R (red). The arrangement and order of the colors may be changed. In the following description, symbols indicating the distinction between Bk, B, G, and R are omitted, and may be simply referred to as a line sensor 7. The four line sensors 7 can be operated simultaneously.

  In the image reading apparatus 100 and the multifunction device 200 according to the present embodiment, it is possible to set on the operation panel 3 whether to read a document in black and white (monochrome mode) or to read a document in color (color mode). Therefore, the operation panel 3 functions as an input unit that receives color settings (selection between the black and white mode and the color mode) during document reading.

  When reading in black and white (monochrome mode), the original is read using the line sensor 7Bk. In other words, when reading in black and white, image data is generated based on the output of the line sensor 7Bk.

  On the other hand, when reading in color (color mode), the original is read using the blue line sensor 7B, the green line sensor 7G, and the red line sensor 7R. In other words, when performing color reading, R, G, and B image data are generated based on the outputs of the line sensor 7B, the line sensor 7G, and the line sensor 7R. The image processing unit 204 of the main control unit 201 can generate luminance information (information indicating black and white) from R, G, and B image data.

  As shown in FIG. 5, the four line sensors 7 are arranged in parallel to each other. In each line sensor 7, light receiving elements 70 (photoelectric conversion elements) are arranged in a line. For example, the line sensor 7B, the line sensor 7G, and the line sensor 7R are provided with a color separation filter for each color. On the other hand, the line sensor 7Bk is not provided with a color separation filter.

  Further, as shown in FIG. 5, for example, the interval between the color reading line sensor 7B and the line sensor 7G and the interval between the line sensor 7G and the line sensor 7R are made equal (interval D1). In the image sensor 15 of the present embodiment, the distance D2 between the black and white line sensor 7Bk and the blue line sensor 7B is twice the distance D1.

  The reading control unit 10 is connected to the home position sensor HS. The home position sensor HS is a sensor that detects that the first moving frame 61 has reached the home position. The first moving frame 61 returns to the home position when the job is completed. The home position can be arbitrarily determined. For example, the home position is set between the placement reading contact glass 12 and the transport reading contact glass 11. In addition, since the position of the 2nd movement frame 62 is decided beforehand according to the position of the 1st movement frame 61, when the 2nd movement frame 62 also returns to a home position by adjusting the 1st movement frame 61 to a home position. I can say that.

  Further, for example, how much the range moved from the home position is that the first moving frame 61 is positioned below the conveyance reading contact glass 11 (the reading line 8 of the image sensor 15 is on the conveyance reading contact glass 11). Information indicating the range of the position is stored in the storage unit 16. When a document is conveyed and read (when a document passing through the conveyance reading contact glass 11 is read), the reading control unit 10 uses the reading line 8 of each line sensor 7 in the image sensor 15 as the conveyance reading contact glass 11. The first moving frame 61 is moved within a range that fits within, and the first moving frame 61 and the second moving frame 62 are fixed below the contact glass 11 for conveyance reading.

  Further, when the reading control unit 10 reads a document placed on the placement reading contact glass 12, the winding motor 65 is operated to place the first moving frame 61 and the second moving frame 62 from the home position. The reading glass 12 is moved from the left end to the right end.

  The A / D converter 17 receives the analog electrical signal of each pixel obtained by the image sensor 15, performs quantization and converts it into a digital signal, and generates image data. Thereby, a pixel value indicating the density is given to each pixel. For example, the A / D conversion unit 17 quantizes R, G, B, and Bk to 8 to 10 bits, for example.

  The correction processing unit 18 receives the image data output from the A / D conversion unit 17 and performs image processing. In the present embodiment, an example in which the correction processing unit 18 is provided in the image reading unit 1 and the image processing unit 204 is provided in the main control unit 201 will be described. However, for example, only one image processing unit 204 is provided on the main body side, and the image processing unit 204 provided with only one image processing unit performs the processing of the correction processing unit 18 and the processing of the image processing unit 204 in this description. May be.

  The correction processing unit 18 includes a work memory that is a work area for processing image data and a circuit for image processing. The correction processing unit 18 corrects distortion derived from characteristics of the light source 610, the image sensor 15, and the like, such as gamma correction and shading correction, on the image data. The image data processed by the correction processing unit 18 is stored in the image memory 10m and then transferred to the main control unit 201. Further, when performing printing, the main control unit 201 transmits the image data after the image processing by the image processing unit 204 to the exposure device 51, and performs printing (toner image formation) based on the image data. Alternatively, when performing transmission, the main control unit 201 transmits the image data after the image processing by the image processing unit 204 to the communication unit 205, and transmits the image data to an external computer 300 or the like.

  Further, the image reading unit 1 is provided with an abnormal pixel detection unit 19 (corresponding to a detection unit). The abnormal pixel detection unit 19 generates black streaks in the image data read by each line sensor 7 based on the output of the image sensor 15 (image data generated by the A / D conversion unit 17 and processed by the correction processing unit 18). Abnormal pixels (pixels that are darker than normal) are detected. For example, the abnormal pixel detection unit 19 generates a streak based on image data of each color when the image sensor 15 (each line sensor 7) reads the white plate 27 before reading the document or between the documents being read. Detect whether or not. Details of the detection of the streaks will be described later.

(Position of reading line 8 on contact glass 11 for conveyance reading)
Next, with reference to FIG. 6, the position of a line for reading with the conveyance reading contact glass 11 of each line sensor 7 of the present embodiment will be described. FIG. 6 is an enlarged explanatory view showing an example of the position of the reading line 8 on the conveyance reading contact glass 11 of each line sensor 7.

  FIG. 6 is a schematic view of the conveyance reading contact glass 11 and the first mirror 611 as viewed from the front side (front side) of the multifunction device 200. For convenience, illustration of the light source 610, the second moving frame 62, and the like is omitted.

  When reading a document conveyed by the document conveying unit 2, the first moving frame 61 is positioned below the conveyance reading contact glass 11. The position of the line (reading line 8) that each line sensor 7 reads in the conveyance reading contact glass 11 depends on the arrangement of each line sensor 7 in the image sensor 15 in the present embodiment. The black and white reading line 8Bk, the blue reading line 8B, the green reading line 8G, and the red reading line 8R are sequentially arranged.

  In this embodiment, the original is read at 600 dpi. Therefore, the reading width of each line sensor 7 (the width of one line in the original, the length of one side of one pixel) is about 42.3 μm (23.4 mm (1 inch) ÷ 600). One pixel corresponds to each light receiving element 70 of each line sensor 7. The range of 42.3 μm on one side of the contact glass or the original is reduced by the lens 14 and converted into the pitch of the light receiving elements 70.

  Further, for example, the distance D3 (between RG and GB) of the color reading line 8 is 12 times one pixel (one line), that is, 42.3 [μm] × 12≈0.5 [mm]. (12 lines). Therefore, the distance D1 between the color line sensors 7 of the image sensor 15 is also a length obtained by dividing about 0.5 mm by the reduction ratio of the lens 14. The interval D4 between the black and white reading line 8Bk and the blue reading line 8B is, for example, 24 times one pixel, that is, 42.3 [μm] × 24≈1.0 [mm] (for 24 lines). .

(Outline of black stripe detection)
Next, an outline of black streak detection (abnormal pixel detection) in this embodiment will be described with reference to FIGS. 4 and 6.

  In the image reading unit 1 of the present embodiment, abnormal pixel detection for detecting whether or not there is a flaw or a stain that causes black streaks in the reading lines 8 of each color on the contact glass 11 for conveyance reading. A portion 19 is provided (see FIG. 4).

  The abnormal pixel detection unit 19 determines the presence / absence of an abnormal pixel that causes black streaks based on image data based on the output of each line sensor 7 when the white plate 27 is read. Originally, since the white plate 27 is read, the pixel values of each pixel in the image data of one main scanning line should be values indicating white. However, if the transport reading contact glass 11 has dirt (for example, dust, dust, glue, ink, etc.) or scratches, the pixel values of the pixels in the position corresponding to the dirt or scratches in the reading line 8 are dirty or scratched. It becomes darker than gray (black or gray). When the original is read, black streaks (dark lines) appear in the sub-scanning direction in the image data, which causes a reduction in image quality.

  Therefore, the abnormal pixel detection unit 19 includes pixels in a direction darker (darker or blacker) than a predetermined threshold in each image data (for example, for one main scanning line) of each color when the white plate 27 is read. It is confirmed whether or not there is a pixel having a value. For example, the predetermined threshold value is stored in the storage unit 16 in the image reading unit 1. Then, the abnormal pixel detection unit 19 reads the threshold value stored in the storage unit 16 and, for each color, whether or not an abnormal pixel having an abnormal pixel value that generates a black streak is included in the image data (whether or not exists). ) Is detected.

  In order to improve the accuracy of detection of abnormal pixels, the white plate 27 is read several times to several tens of times (for example, 10 times) at the same position, and the abnormal pixel detection unit 19 reads each image data obtained by reading. The presence / absence of abnormal pixels in the image data for one line of each line sensor 7 is determined, and if there is an abnormal pixel at the same position more than a predetermined number of times (for example, 5 times or more), You may judge. Alternatively, the abnormal pixel detection unit 19 calculates an average value of the pixel values of each pixel for each image data obtained by reading, and compares the average value with a threshold value to determine whether or not there are abnormal pixels in the line image data. May be detected. If abnormal pixels can be detected, the processing procedure of abnormal pixel detection is not limited to the above.

  The abnormal pixel detection unit 19 notifies the reading control unit 10 of information indicating colors that include abnormal pixels and colors that do not include abnormal pixels. In other words, the abnormal pixel detection unit 19 informs the reading control unit 10 of the color (line sensor 7) in which scratches and dirt are present on the reading line 8 on the conveyance reading contact glass 11 and the position of the pixel corresponding to the scratches and dirt. Notice.

  If the abnormal pixel detection unit 19 detects the presence of abnormal pixels in the image data of each color (each line sensor 7) obtained by reading the white plate 27, the reading control unit 10 conveys each line sensor 7. Each winding frame can be moved by operating the take-up motor 65 so that the position of the reading line 8 on the reading contact glass 11 becomes a position free from scratches, dirt, dust, and the like. For example, the reading control unit 10 moves the first moving frame 61 in units of the interval D3 between the reading lines 8 for each color (in this embodiment, 12 pixels). In this case, in order to set the position of the reading line 8 to a position to avoid scratches and dirt, the reading control unit 10 gives a pulse that is an integral multiple of 12 to the winding motor 65, and the first line 12 (12 pixels) is the first. The moving frame 61 is moved (details will be described later).

(Flow of black line avoidance control)
Next, an example of a control flow for avoiding black streak generation in color reading according to the present embodiment will be described with reference to FIGS. 7 and 8 are flowcharts showing an example of the flow of black stripe generation avoidance control before the start of document reading in color reading (color mode). FIG. 9 is an enlarged explanatory view showing an example of a state in which the position of the reading line 8 of each line sensor 7 is set to the reference line position 9. FIG. 10 is an enlarged explanatory diagram showing an example of a state where the position of the reading line 8B of the line sensor 7B for the reference color is set to the reference line position 9G for the adjacent color. FIG. 11 is an enlarged explanatory view showing an example of a state in which the position of the reading line 8B of the reference color line sensor 7B is set to a reference line position 9R of a color that is not adjacent. FIG. 12 is an enlarged explanatory diagram showing an example of a state in which the position of the reading line 8B of the reference color line sensor 7B is set to the reference line position 9Bk of the line sensor 7Bk for monochrome reading. A series of processing is divided into FIGS. 7 and 8.

  First, in the image reading apparatus 100 of the present embodiment, when reading an original in color, a blue line sensor 7B, a green line sensor 7G, and a red line sensor 7R are used. In other words, the reading control unit 10 operates the line sensor 7B, the line sensor 7, and the line sensor 7R during color reading, and generates image data based on the output results of the line sensor 7B, the line sensor 7, and the line sensor 7R. Then, the image processing unit 204 also generates monochrome (luminance) image data from the image data of each color. Note that the reading control unit 10 operates the monochrome reading line sensor 7Bk during monochrome reading, and generates image data based on the output result of the line sensor 7Bk.

  Note that the operation panel 3 accepts the setting for whether the original is read in color or black and white. In accordance with the setting made on the operation panel 3, the reading control unit 10 drives the line sensor 7 necessary for reading.

  Hereinafter, the flow of avoiding black streaks when the original is conveyed from the original conveying unit 2 and the original is read in color will be described with reference to FIGS. First, the start of FIG. 7 is the time when the start key 32 is pressed on the operation panel 3 and the document is transported from the document transport unit 2 to start reading the document in color for copying or transmission.

  When the original is conveyed from the original conveying unit 2 and the original reading is started in color, the reading control unit 10 first determines the position of the reading line 8 on the conveyance reading contact glass 11 of the line sensor 7 of each color. Each moving frame is moved so as to be the reference line position 9 (step # 1). In other words, the reading control unit 10 moves each moving frame from the home position to the reference reading position. For example, information indicating how much each moving frame is moved from the home position is the reference reading position is stored in the storage unit 16. The reading control unit 10 reads the information in the storage unit 16 and controls the winding motor 65 to move each moving frame so that it becomes the reference reading position.

  Here, the reference line position 9 and the reference reading position will be described with reference to FIG. In the image reading apparatus 100 according to the present embodiment, as shown by black circles in FIG. 9, the position (reference line position 9) serving as a reference for the reading line 8 on the conveyance reading contact glass 11 for the line sensor 7 of each color. Is predetermined. In FIG. 9, the reference position of the reading line 8R of the red line sensor 7R is shown as a reference line position 9R, the reference position of the reading line 8G of the green line sensor 7G is shown as a reference line position 9G, and A reference position of the reading line 8B of the line sensor 7B is indicated as a reference line position 9B, and a reference position of the reading line 8Bk of the line sensor 7Bk for black and white reading is indicated as a reference line position 9Bk.

  The distance between the red reference line position 9R and the green reference line position 9G and the distance between the green reference line position 9G and the blue reference line position 9B according to the distance between the reading lines 8 are the distance D3 described above. (12 lines). Further, the distance between the blue reference line position 9B and the black and white reading reference line position 9Bk is equal to the distance D4 (24 lines).

  For example, the reference line position 9 of each color is set to a position where the original passing through the transport reading contact glass 11 can be read most appropriately in terms of design, specifications, accuracy and depth of field ( Predetermined). In other words, for example, when the position of each color reading line 8 is aligned with the reference line position 9, the reference line position 9 is set so that the image quality is the best. The reference reading position is a (state) in which the position of the reading line 8 of the line sensor 7 of each color is combined with the corresponding reference line position 9. FIG. 9 shows a state in which each moving frame is moved so that the reading control unit 10 controls the winding motor 65 to reach the reference reading position.

  When the original is conveyed to the original conveying unit 2 and color reading is performed, the reading control unit 10 controls the winding motor 65 so that the position of the reading line 8 of the line sensor 7 of each color becomes the reference reading position. Each moving frame is moved (step # 1). Then, the reading control unit 10 turns on the light source 610 and drives the image sensor 15 to operate the optical unit including each moving frame and the reading unit including the image sensor 15 to read the white plate 27. (Step # 2).

  Subsequently, the reading control unit 10 detects whether there is an abnormal pixel in any of the image data of each color obtained by reading the white plate 27 (of the image sensor 15 of each color). Whether any one has read a flaw or dirt) is caused to be performed by the abnormal pixel detection unit 19 (step # 3). In other words, the abnormal pixel detection unit 19 checks whether or not there is an abnormal pixel in any of the image data of each color (step # 3).

  If there are abnormal pixels (Yes in step # 3), black streaks will occur even if reading is performed in the current state, so the reading control unit 10 controls the winding motor 65 to control the reference color. The movement of each moving frame is started so that the position of the reading line 8 becomes the reference line position 9 of the color adjacent to the reference color (step # 4).

  Here, the movement of the position of the reference color reading line 8 to the reference line position 9 of the color adjacent to the reference color will be described with reference to FIG.

  First, the reference color is a color in which the position of the reading line 8 is at the end in the sub-scanning direction among the multi-color line sensors 7B, 7G, and 7R used for color reading. In the present embodiment, a description will be given using blue as a reference color. Note that red may be used as a reference color.

  Then, the reading control unit 10 controls the winding motor 65 so that the position of the reference color (blue) reading line 8B becomes the reference line position 9G of the color (green) adjacent to the reference color. Move. FIG. 10 shows an example of a state in which the position of the reference color (blue) reading line 8B is set to the green reference line position 9G. In other words, the reading control unit 10 controls the winding motor 65 to change the position of the blue reading line 8B from the reference line position 9B of the reference color (blue) to the green color that is the closest to the reference color (blue). The movement toward the reference line position 9G is started (step # 4).

  The reading control unit 10 causes the reading unit to read the white plate 27 while moving each moving frame so that the reference color (blue) reading line 8B is positioned at the green reference line position 9G. The control unit 10 is a line in which abnormal pixels are not detected (no abnormal pixels) among lines in the main scanning direction (for example, 12 lines) within the interval between the blue reference line position 9B and the green reference line position 9G. It is confirmed whether there is any undetected reading line (step # 5).

  Then, the movement of each moving frame to the position where the position of the reading line 8B for the reference color (blue) becomes the reference line position 9G for the color (green) adjacent to the reference color is completed (step # 6). Then, the reading control unit 10 operates reading units such as the optical unit and the image sensor 15, and causes the reading unit to read the white plate 27 (step # 7).

  Subsequently, the reading control unit 10 selects one of the color image data obtained by reading the white plate 27 with the reference color (blue) reading line 8B at the green reference line position 9G. The abnormal pixel detector 19 is made to detect whether or not there is an abnormal pixel in the image data (step # 8).

  If there is an abnormal pixel (Yes in step # 8), black streaks will occur even if reading is performed in the current state, so the reading control unit 10 controls the winding motor 65 to control the reference color. The movement of each moving frame is started so that the position of the (blue) reading line 8 becomes the reference line position 9 of the color (red) for color reading not adjacent to the reference color (step # 9).

  Here, the movement of the position of the reference color reading line 8B to the reference line position 9R of the color reading color (red) not adjacent to the reference color (blue) will be described with reference to FIG.

  The reading control unit 10 controls the winding motor 65 so that the position of the reference color (blue) reading line 8B becomes the reference line position 9R of the color (red) for color reading and not adjacent to the reference color. Move the moving frame. As a result, the movement of the position of the reference color reading line 8B from the green reference line position 9G toward the red reference line position 9R is started.

  FIG. 11 shows an example of a state in which the position of the reference color (blue) reading line 8B is set to the red reference line position 9R. In other words, the reading control unit 10 controls the winding motor 65 toward the reference line position 9R that is not adjacent to the reference color (blue), and starts moving the position (each moving frame) of the blue reading line 8B. (Step # 9).

  As described above, the reading control unit 10 moves each moving frame (the light source 610 and the lamp) by the winding motor 65 or the like until it is detected that there is no abnormal pixel in any color image data in the color mode. Thus, a movement process for sequentially moving the position of the reference color reading line 8B to the reference line positions 9G and R of other colors is performed.

  The reading control unit 10 causes the reading unit to read the white plate 27 while moving each moving frame so that the reference color (blue) reading line 8B is positioned at the red reference line position 9R. The control unit 10 is a line in which no abnormal pixel is detected (no abnormal pixel) among lines in the main scanning direction (for example, 12 lines) within the interval between the green reference line position 9G and the red reference line position 9R. It is confirmed whether there is any undetected reading line (step # 10).

  Then, the movement of each moving frame to the position where the position of the reference color (blue) reading line 8B becomes the reference line position 9R of the color for reading color (red) that is not adjacent to the reference color is completed (step # 11). (Flow is from FIG. 7 to FIG. 8). Then, the reading control unit 10 operates reading units such as the optical unit and the image sensor 15, and causes the reading unit to read the white plate 27 (step # 12).

  Subsequently, the reading control unit 10 selects one of the image data of each color obtained by reading the white plate 27 in a state where the reference color (blue) reading line 8B is at the red reference line position 9R. The abnormal pixel detector 19 is made to detect whether or not there is an abnormal pixel in the image data (step # 13).

  If there is an abnormal pixel (Yes in Step # 13), black streaks occur even if the position of the reference line (B) for the reference color (blue) is set as the reference line position 9 for any line sensor 7 for color reading.

  Therefore, when there is an abnormal pixel (Yes in Step # 13), the reading control unit 10 checks whether or not there is an undetected reading line between the blue reference line position 9B and the green reference line position 9G. (Step # 14). Whether each line between the reference line position 9B and the reference line position 9G is a non-detection reading line (whether an abnormal pixel is included in each line between the reference line position 9B and the reference line position 9G). ) Has already been recognized in step # 5.

  If there is an undetected reading line between B and G (Yes in Step # 14), the reading control unit 10 controls the take-up motor 65 so that the position of the blue reading line 8B is the reference line position 9B and the reference line position 9B. Each moving frame is moved so as to be the position of the non-detection reading line between the line positions 9G (the position where the abnormal pixel is not detected) (step # 15). As a result, the control for avoiding black streaking before reading the document ends, the document conveyance control unit 20 operates the document conveyance motor 28, and the reading control unit 10 turns on the light source 610 and operates the image sensor 15. The document is read by the reading unit (end).

  On the other hand, if there is no non-detected reading line between the reference line position 9B and the reference line position 9G (No in step # 14), the reading control unit 10 does not detect the difference between the green reference line position 9G and the red reference line position 9R. It is confirmed whether or not there is a detection reading line (step # 16). Whether each line between the reference line position 9G and the reference line position 9R is an undetected reading line (whether an abnormal pixel is included in each line between the reference line position 9G and the reference line position 9R). ) Has already been recognized in step # 10.

  If there is an undetected reading line between G and R (Yes in Step # 16), the reading control unit 10 controls the take-up motor 65 so that the position of the blue reading line 8B is the reference line position 9G and the reference line position 9G. Each moving frame is moved so as to be the position of the non-detection reading line between the line positions 9R (the position where no abnormal pixel is detected) (step # 17). As a result, the control for avoiding black streaking before reading the document is finished, the document conveyance control unit 20 operates the document conveyance motor 28, and the reading control unit 10 causes the reading unit to read the document (end).

  On the other hand, if there is no undetected read line between the reference line position 9G and the reference line position 9R (No in step # 16), it is considered that there is dirt or a scratch from the blue reference line position 9B to the red reference line position 9R. . Therefore, the reading control unit 10 sets the position of the reference color (blue) reading line 8B to the black reference line position 9Bk located on the opposite side of the red reference line position 9R from the blue reference line position 9B. Each moving frame is moved (step # 18). The reading control unit 10 may move each moving frame so that the position of the reference color reading line 8B is further away from the black reference line position 9Bk when viewed from the reference color reference line position 9B. . Thereby, the black stripe occurrence probability can be reduced even a little.

  Here, the movement of the position of the reading line 8B for the reference color (blue) to the reference line position 9Bk for monochrome reading will be described with reference to FIG. Reference line positions 9B, 9G, and 9R for color reading when there is an abnormal pixel even if moved to the reference color reading line 8Bk and between the reference line position 9B and the reference line position 9G When there is no non-detection reading line between 9G and the reference line position 9R, the reading control unit 10 controls the take-up motor 65, and finally the position of the reference color (blue) reading line 8B is for monochrome reading. Each moving frame is moved so as to be the reference line position 9Bk. Therefore, the movement of the position of the reference color reading line 8B from the red reference line position 9R toward the black and white reading reference line position 9Bk is started.

  Then, as shown in FIG. 12, the reading control unit 10 sets the position of the reading line 8B for the reference color (blue) to the reference line position Bk for black and white reading. Then, the control for avoiding black streaking before the document reading is finished, the document conveyance control unit 20 operates the document conveyance motor 28, and the reading control unit 10 causes the reading unit to read the document (END).

  In step # 3, step # 8, and step # 13, when the abnormal pixel detection unit 19 does not detect an abnormal pixel in any color image data (when no abnormal pixel exists in all color image data, No in step # 3, No in step # 8, No in step # 13) If the original is read at the current position of each moving frame, it is considered that no black streak occurs. Therefore, in step # 3, step # 8, and step # 13, when the abnormal pixel detection unit 19 does not detect an abnormal pixel in any color image data, the reading control unit 10 determines the current position of each moving frame (for each color). It is set to read the original at the position of the reading line 8) (step # 19). Then, the control for avoiding black streaking before the document reading is finished, the document conveyance control unit 20 operates the document conveyance motor 28, and the reading control unit 10 causes the reading unit to read the document (END).

(Flow of black line avoidance control)
Next, an example of a control flow for avoiding black streaks during black and white reading in the image reading apparatus 100 according to the present embodiment will be described with reference to FIGS. 13 and 14. FIG. 13 is a flowchart illustrating an example of a control flow for storing presence / absence of abnormal pixels during document reading. FIG. 14 is a flowchart illustrating an example of the flow of black streak generation avoidance control at the start of document reading.

  First, the image reading apparatus 100 (reading control unit 10) of the present embodiment performs black and white stripes on the image data of each color at the time of black and white reading or at the position of each moving frame (first moving frame 61) at the time of the previous document reading. Presence / absence information indicating whether or not an abnormal pixel that generates the error is included is stored in association with the position information of the first moving frame 61 (for example, stored in the storage unit 16). The storage of the presence / absence information associated with the position information is used to avoid the occurrence of black streak from the first original reading at the time of the next original reading.

  In addition, since the position of the 2nd moving frame 62 with respect to the position of the 1st moving frame 61 is decided beforehand by the wiring 63, the position of the 2nd moving frame 62 can also be handled as position information. In the embodiment, description will be made assuming that position information based on the position of the first moving frame 61 is handled.

  Accordingly, a flow of storage control of presence / absence information associated with position information of the first moving frame 61 at the time of reading a document in black and white will be described. The presence / absence information associated with the position information of the first moving frame 61 can also be stored while a plurality of documents are being conveyed from the document conveying unit 2 (for example, between documents). However, for example, it is also conceivable that the cause of contamination such as ink, glue or correction liquid adhering to the document adheres to the contact glass 11 for transport reading during document transport. Therefore, in this description, an example in which presence / absence information is stored in association with the position information of the first moving frame 61 when the reading of the last page among the documents placed on the document tray 21 is completed will be described.

  First, the start in FIG. 13 is a point in time when document reading in black and white using the document transport unit 2 (document reading by the line sensor 7Bk for monochrome reading) is started. Then, the reading control unit 10 checks whether or not the last page of the documents placed on the document tray 21 is read (step # 21). Whether or not the document of the last page is read is determined based on the output of the document detection sensor 29 (see FIG. 4). For example, the document detection sensor 29 is a reflective or transmissive optical sensor provided on the upper surface of the document tray 21. The output of the document detection sensor 29 changes depending on whether the document on the document tray 21 is detected or not. The document detection sensor 29 is not limited to an optical sensor, and may be any sensor that can detect the presence or absence of a document.

  The document conveyance control unit 20 confirms the output of the document detection sensor 29 during document conveyance, and detects that there is no document from the document tray 21. The document conveyance control unit 20 notifies the reading control unit 10 that there are no more documents from the document tray 21. When this notification is received, the reading control unit 10 recognizes that the document of the last page has been read.

  If it is not the last page (No in step # 21), the reading control unit 10 continues to wait for a notification from the document conveyance control unit 20 (loop in step # 21). During this loop, the reading control unit 10 and the document conveyance control unit 20 control reading of the document, and each page of the document is read.

  On the other hand, if it is the last page (Yes in step # 21), the reading control unit 10 does not move each moving frame (the first moving frame 61 and the like) and reads the white plate 27 after the document passes. The image sensor 15 is made to perform (step # 22). At this time, the line sensors 7 for all colors read. During reading of the white plate 27, the reading control unit 10 turns on the light source 610.

  The abnormal pixel detection unit 19 includes abnormal pixels that generate black streaks in the image data of each color (for example, image data for one main scanning line) generated based on the output of the line sensor 7 of each color. (Step # 23).

  Then, based on the detection result of the abnormal pixel detection unit 19, the reading control unit 10 relates to the current position information of the first moving frame 61 (the amount of movement from the home position, for example, the number of pulses from the home position), Presence / absence information indicating the presence / absence of abnormal pixels for each color is stored in the storage unit 16 (step # 24).

  For example, if no abnormal pixels are included in the image data for all colors, the reading control unit 10 stores presence / absence information indicating that abnormal pixels are not included for all colors in association with the position information of the first moving frame 61. 16 to memorize. Further, for example, if an abnormal pixel exists only in red image data, the reading control unit 10 associates the positional information of the first moving frame 61 with the abnormal pixel in red, and colors other than red (monochrome, Presence / absence information indicating that abnormal pixels are not included in blue and green) is stored in the storage unit 16. Thereby, the storage control of the position information and the presence / absence information ends (end).

  Next, based on FIG. 14, the flow of black stripe generation avoidance control when the original is conveyed to the original conveying unit 2 and the original is read in black and white will be described. The start in FIG. 14 is when the main control unit 201 notifies the image reading apparatus 100 (the reading control unit 10 and the document conveyance control unit 20) that the document reading start request has been met. For example, when the start key 32 of the operation panel 3 is pressed for copying or transmitting image data, a document reading start request is made. At this time, the main control unit 201 notifies the reading control unit 10 together with information indicating the color setting for reading on the operation panel 3 (whether reading in the monochrome mode or reading in the color mode).

  Upon receiving this notification, at the time of monochrome reading, the reading control unit 10 confirms the position information and presence / absence information of the first moving frame 61 in the previous reading stored in the storage unit 16 (step # 31). Based on the presence / absence information, the reading control unit 10 checks whether or not an abnormal pixel has been detected in the image data of any color at the position of the first moving frame 61 in the previous reading (step # 32). ).

  If there is no abnormal pixel (No in step # 32), the reading control unit 10 rotates the winding motor 65 based on the position information in the previous reading so that the previous reading position becomes the pre-conveyance position. The first moving frame 61 is moved to (# 33).

  On the other hand, if there is an abnormal pixel (Yes in step # 32) and black streak is likely to occur, the reading control unit 10 moves the first moving frame 61 with a position different from the previous reading as a pre-conveyance position ( Step # 34). As will be described later, abnormal position information indicating the position of the first moving frame 61 when abnormal pixels are detected in image data of any color, and abnormal color information indicating the color at which the abnormal pixels are detected. It can be accumulated and stored in the storage unit 16. Therefore, when the first moving frame 61 is moved to the pre-conveyance position in step # 34, the reading control unit 10 sets, based on the abnormal position information, a position where no abnormal pixel is detected in any color as the pre-conveyance position. The first moving frame 61 is moved.

  In any case, the reading line 8 of each line sensor 7 on the conveyance reading contact glass 11 of each color is set at a position where there is a high possibility that there is no scratch or dirt in the conveyance reading contact glass 11.

  The reading controller 10 turns on the light source 610 with the first moving frame 61 fixed at the pre-conveyance position, and causes all the line sensors 7 of the image sensor 15 to read the white plate 27 (step #). 35). Then, the abnormal pixel detector 19 detects an abnormal pixel that generates black streaks on the line in the main scanning direction based on the image data of each color (step # 36).

  The reading control unit 10 receives the detection result of the abnormal pixel detection unit 19 and confirms whether or not the abnormal pixel is included in the image data of the monochrome line sensor 7Bk (step # 37). In other words, the reading control unit 10 checks whether there are any scratches, dirt, or the like on the reading line 8 on the conveyance reading contact glass 11 of the line sensor 7Bk (step # 37).

  If the abnormal pixel is not included in the image data of the monochrome line sensor 7Bk (No in step # 37), the reading control unit 10 sets the pre-conveyance position as the original reading execution position (step # 38). . In other words, the reading control unit 10 causes the original to be read using the monochrome line sensor 7Bk while the first moving frame 61 is fixed at the pre-conveyance position.

  On the other hand, if the abnormal pixel is included in the image data of the black and white line sensor 7Bk (if black streak occurs, Yes in step # 37), the reading control unit 10 detects the detection result of the abnormal pixel detection unit 19. Based on the above, it is confirmed whether the image data of the color reading line sensor 7 (line sensor 7B, line sensor 7G, line sensor 7R) includes an abnormal pixel (step # 39).

  If there is a color that does not include an abnormal pixel in the image data (No in step # 39), the reading control unit 10 reads the reading line on the conveyance reading contact glass 11 that does not include the abnormal pixel. Each winding frame (first moving frame 61) is moved by controlling the winding motor 65 so that the position 8 becomes the position of the reading line 8Bk of the line sensor 7Bk for black and white (step # 40).

  On the other hand, if there is an abnormal pixel in the image data for all colors (Yes in step # 39), the reading control unit 10 moves the first moving frame 61 and moves the position shifted from the pre-conveyance position to read the document. The execution position is set (step # 41). For example, the reading control unit 10 determines that the position of the reading line 8 on the conveyance reading contact glass 11 of each color after movement is the reading line 8 on the conveyance reading contact glass 11 of any color at the pre-conveyance position. The first moving frame 61 is moved to a position that does not overlap with the first position. Alternatively, the reading control unit 10 may move the first moving frame 61 to a position where no abnormal pixel has been detected.

  After step # 40 and step # 41, the reading control unit 10 detects abnormal position information indicating the position of the first moving frame 61 when the abnormal pixel is detected, and abnormal information indicating the color where the abnormal pixel is detected. The color information is stored in the storage unit 16 (step # 42). Then, after step # 24, this control is finished, and the document conveying section 2 actually starts document conveyance, and the image reading section 1 starts reading the document (END).

  As described above, the image reading apparatus 100 according to the present embodiment sandwiches the document transport unit 2 that transports the document toward the contact glass (conveyance reading contact glass 11) and the document transported with the contact glass. A white plate 27 provided, an image sensor 15 including line sensors 7 (for example, line sensors 7B, 7G, and 7R) for at least three colors for color reading, and contact glass and the white plate 27 in the main scanning direction. An optical unit (a first moving frame 61, a second moving frame 62, a light source 610, a first mirror 611, a second mirror 622, a third mirror 623, etc.) that irradiates light along and guides the reflected light to the image sensor 15. , A moving unit (winding motor 65, winding drum 64, wire 63, etc.) that moves the optical unit in the sub-scanning direction, and an image sensor Based on the output of 15, a generation unit (A / D conversion unit 17) that generates image data of each color, and a detection unit (abnormal pixel detection unit 19) that detects the presence or absence of abnormal pixels that generate black streaks based on the image data The reference line position 9 (reference line positions 9B, 9G, 9R) that is the reference position of the reading line 8 (for example, 8B, 8G, 8R) on the contact glass of each line sensor 7 is previously Before the reading of the document is started, the moving unit detects that there is no abnormal pixel in the image data of each color based on the output of each line sensor 7 for color reading. The position of the reading line 8 (for example, 8B) of the line sensor 7 (for example, line sensor 7B) of the reference color (for example, blue) which is the edge color is set to the reference line position 9 (for example, other color). The optical unit is moved in order from colors close to the reference color so as to be the reference line position 9G and the reference line position 9R), and the position of the reading line 8 of the reference color line sensor 7 is determined by the movement process. Each time the image is moved to the reference line position 9 of another color, the reading unit performs reading, and the detection unit detects whether there is an abnormal pixel in the image data of each color, and reads the reference color line sensor 7. In a state where the position of the line 8 is moved to the reference line position 9 of another color in which there is no abnormal pixel in the image data of each color, the document transport unit 2 transports the document, and the reading unit reads the document.

  As a result, the document reading is performed after all of the color reading line sensors 7 (for example, 7B, 7G, and 7R) have no stains or scratches on the respective reading lines 8 (for example, 8B, 8G, and 8R). Is executed. Accordingly, it is possible to reduce the black stripe occurrence probability in the read image data of the document. Further, the movement process is performed before the document reading is started, and the position of the reading line 8 of the line sensor 7 of each color is shifted to a position free from dirt and scratches before the document reading is started. Can be eliminated. Also, by design, the reference line position 9 (reference line positions 9B, 9G, 9R) is set so that the reading result is the best (for example, less blur) in relation to accuracy and depth of field. However, the position of the reading line 8 (for example, the reading line 8B) of the line sensor 7 (for example, the line sensor 7B) of at least the reference color (for example, blue) is changed to the reference line position 9 (for example, the reference line position 9G) of another color. Therefore, it is possible to read the document while avoiding deterioration in image quality of the image data of the document obtained by reading.

  Further, the reading unit moves the position of the reading line 8 (for example, reading line 8B) of the reference color (for example, blue) from the reference line position 9 (for example, reference line position 9B) of the reference color to the color adjacent to the reference color. While moving to a reference line position 9 (for example, the reference line position 9G), reading is performed, and the detection unit (abnormal pixel detection unit 19) is a color adjacent to the reference color from the reference line position 9 of the reference color. Before the reference line position 9, it is confirmed whether or not there is a non-detection reading line that is a line having no abnormal pixels in the image data of each color, and the position of the reference color reading line 8 is set to any reference color. If there is an abnormal pixel in the image data of each color even if it is moved to the line position 9, the moving unit (winding motor 65, winding drum 64, wire 63, etc.) reads the position of the reference color reading line 8 without detection. The position of the line After moving the optical unit (the first moving frame 61, the second moving frame 62, the light source 610, the first mirror 611, the second mirror 622, the third mirror 623, etc.) as described above, the document conveying unit 2 reads the document. The document is conveyed, and the reading unit reads the document. As a result, the positions of the reading lines 8 for each color (for example, 8B, 8G, 8R) deviate from the reference line position 9 (reference line positions 9B, 9G, 9R), but the positions of the reading lines 8 for all colors are changed to image data. It can be adjusted to a position where there are no dirt or scratches that cause black streaks. Therefore, it is possible to eliminate the occurrence of black streaks in the image data obtained by reading the original from the first original and the printed matter based on the image data.

  Further, the moving process is performed so that the position of the reading line 8 (for example, reading line 8B) of the reference color (for example, blue) becomes the reference line position 9 (for example, the reference line position 9R) of the color not adjacent to the reference color. The reading unit performs reading, and the detection unit (abnormal pixel detection unit 19) moves the reference line position 9 (for example, the reference line position 9G) of the color after the movement from the reference line position 9 (for example, the reference line position 9G) of the color before the movement. , Whether or not there is a non-detected reading line between the reference line position 9R), and the position of the reference color reading line 8 is moved to the reference line position 9 of any color, the image data in each color When there is an abnormal pixel and there is no undetected reading line from the reference line position 9 of the reference color to the reference line position 9 of the color adjacent to the reference color, the moving unit (winding motor 65, winding drum) 64, wire 63, etc.) The optical unit (the first moving frame 61, the second moving frame 62, the light source 610, the first mirror 611, the first moving frame 61, the second moving frame 62, and the position of the non-detection reading line confirmed between the reference line positions 9 of colors other than the reference color. After the second mirror 622, the third mirror 623, and the like are moved, the document conveying unit 2 conveys the document, and the reading unit reads the document. As a result, the moving distance of the reference color from the reference line position 9 becomes relatively long, but the positions of all the color reading lines 8 (for example, 8B, 8G, 8R) It can be adjusted to a position where there is no scratch. Therefore, it is possible to eliminate the occurrence of black streaks in the image data obtained by reading the original from the first original and the printed matter based on the image data.

  The image sensor 15 includes a line sensor 7 (line sensor 7Bk) for black and white reading, and the position of the reference line (for example, blue) of the reading line 8 (for example, the reading line 8B) is set to the reference line position 9 of any color. If there is an abnormal pixel in the image data of each color even if it is moved to (reference line positions 9B, 9G, 9R), and there is no undetected read line between any reference line positions 9, the moving part (winding The motor 65, the winding drum 64, the wire 63, etc.) are optically arranged so that the position of the reference color reading line 8 becomes a predetermined reference line position 9 (reference line position 9Bk) for the line sensor 7 for black and white reading. Parts (the first moving frame 61, the second moving frame 62, the light source 610, the first mirror 611, the second mirror 622, the third mirror 623, etc.) are moved, and then the document conveying unit 2 conveys the document. , The reading section reads the document. As a result, when the contact glass (conveying / reading contact glass 11) is soiled or scratched in a considerably wide range, the position of the reading line 8 (for example, 8B, 8G, 8R) of each image sensor 15 is stained or scratched. It can be set as the position where possibility that it has adhered is low. Further, as described above, the reference line position 9 is set so as to obtain the best reading result by design. The position of the reading line 8 of the reference color line sensor 7 is set to the position of the line sensor 7 for monochrome reading. Since the reference line position 9 is set, it is possible to read the document while avoiding deterioration in image quality of the image data of the document obtained by reading.

  Further, the moving unit (winding motor 65, winding drum 64, wire 63, etc.) reads the reading lines 8 (for example, 8B, 8G) of the respective line sensors 7 (for example, 7B, 7G, 7R) before starting the reading of the document. , 8R) at the reference reading position where the position of the reference line position 9 (reference line positions 9B, 9G, 9R) is at the optical unit (first moving frame 61, second moving frame 62, light source 610, first mirror 611, first mirror 611, 2 mirror 622, third mirror 623, etc.), and whether the detection unit (abnormal pixel detection unit 19) has abnormal pixels in the image data of each color obtained by the reading unit reading at the reference reading position If there is an abnormal pixel in the image data of each color, the moving unit performs a moving process. If there is no abnormal pixel in the image data of each color, the document conveying unit 2 is in the state of the reference reading position. The reading unit Carry out the reading of the document. As a result, the position of the reading line 8 of each line sensor 7 is set as the reference line position 9, and if no abnormal pixel is detected and black streak does not occur, the position of the reading line 8 of each color is set as an ideal position. The original can be read in the state.

  Further, the image forming apparatus (for example, the multifunction device 200) includes the image reading apparatus 100 described above. As a result, document reading is performed after the color line sensors 7 (for example, 7B, 7G, and 7R) have no dirt or scratches on the reading lines 8 (for example, 8B, 8G, and 8R). Therefore, printing can be performed based on the image data of the original without black streaks. In addition, black streaks are prevented from occurring on the first sheet of the document. Accordingly, it is possible to provide a high-quality image forming apparatus in which black streak does not occur in color reading.

  As for reading in the monochrome mode, the image reading apparatus 100 according to the present embodiment includes a document transport unit 2 that transports a document toward the contact glass (conveyance reading contact glass 11), and a document transported with the contact glass. A white plate 27 provided so as to sandwich the image, an image sensor 15 that reads a line in the main scanning direction, and an original that passes through the contact glass is irradiated with light along the main scanning direction, and reflected light from the original is imaged. An optical unit (first moving frame 61, second moving frame 62) that leads to the sensor 15, a moving unit (winding motor 65, winding drum 64, wire 63, etc.) that moves the optical unit in the sub-scanning direction, and image Based on the output of the sensor 15, a generation unit (A / D conversion unit 17) that generates image data, and abnormal pixels that generate black streaks are detected based on the image data. An intelligent unit (abnormal pixel detection unit 19), a storage unit 16 for storing position information of the optical unit in the previous reading, and presence / absence information indicating the presence / absence of abnormal pixels in the previous reading corresponding to the position information; Before starting the reading of the document, the moving unit is based on the presence / absence information, and if there is no abnormal pixel in the previous reading, it is in the same position as the previous document reading, and if there is an abnormal pixel in the previous reading, the moving unit The optical unit is moved to a pre-conveyance position that is different from the original reading position, the optical unit emits light toward the contact glass at the pre-conveyance position, the image sensor 15 performs reading, and the abnormal pixel detection unit 19 performs conveyance. The moving unit detects the presence or absence of abnormal pixels in the image data at the previous position, and when the abnormal pixel detection unit 19 does not detect the presence of abnormal pixels, the moving unit does not move the optical unit when starting document reading and detects abnormal pixels. When the section 19 detects the presence of abnormal pixel, moving the optical unit at a position different from the position before the transport before the start document reading.

  The moving parts (winding motor 65, winding drum 64, wire 63, etc.) move the optical parts (first moving frame 61, second moving frame 62) to the pre-conveyance position. As a result, the line position where the image sensor 15 reads in the contact glass (conveyance reading contact glass 11) (position of the reading line 8) is set to a position where there is a high possibility that there will be no scratches or dirt that cause streaks. Can be matched. Therefore, the black streak occurrence probability in the read image data can be lowered. In addition, before starting the reading of the document, the presence or absence of scratches or dirt on the reading line 8 on the contact glass at the pre-conveyance position is checked in advance. The optical unit is moved if there is a risk of black stripes being generated. Therefore, the position of the reading line 8 on the contact glass of the image sensor 15 can be adjusted to a position where no streaking occurs by reading the line once before starting the document reading. Generation of black streaks can be eliminated.

  The embodiment of the present invention has been described above, but the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used for an image reading apparatus and an image forming apparatus including the image reading apparatus.

11 Contact glass for transport reading (contact glass)
DESCRIPTION OF SYMBOLS 1 Image reading part 15 Image sensor 17 A / D conversion part (generation part) 19 Abnormal pixel detection part (detection part)
2 Document Conveying Section 27 White Plate 61 First Moving Frame (Optical Section) 610 Light Source (Optical Section)
611 First mirror (optical unit) 62 Second moving frame (optical unit)
622 2nd mirror (optical part) 623 3rd mirror (optical part)
63 Wire (moving part) 64 Winding drum (moving part)
65 Winding motor (moving part) 7 Line sensor 7B Line sensor (blue) 7G Line sensor (green)
7R line sensor (red) 7Bk line sensor (for monochrome reading)
8B Reading line (Blue) 8G Reading line (Green)
8R reading line (red) 8Bk reading line (for monochrome reading)
9B Reference line position (blue) 9G Reference line position (green)
9R Reference line position (red) 9Bk Reference line position (for black and white reading)
200 MFP (image forming device)

Claims (4)

A document transport section that transports the document toward the contact glass;
A white plate provided so as to sandwich the contact glass and the document to be conveyed;
An image sensor including a line sensor for at least three colors for color reading; and an optical unit that irradiates light along a main scanning direction toward the contact glass and the white plate, and guides reflected light to the image sensor; A reading unit including:
A moving unit that moves the optical unit in the sub-scanning direction;
A generating unit that generates image data of each color based on the output of the image sensor;
A detection unit that detects the presence or absence of abnormal pixels that generate black stripes based on image data,
A reference line position that is a reference position of a reading line on the contact glass of each of the line sensors is predetermined,
Before starting to scan the document,
The moving unit detects a reference color that is an end color in the sub-scanning direction until the detecting unit detects that the abnormal pixel is not present in the image data of each color based on the output of each line sensor for color reading. A movement process is performed in which the position of the reading line of the line sensor is moved in order from the color close to the reference color so as to be the reference line position of another color,
Each time the position of the reading line of the line sensor of the reference color is moved to the reference line position of another color by the moving process, the reading unit performs reading, and the detection unit includes in the image data of each color. Detecting whether or not the abnormal pixel is present,
In a state where the position of the reading line of the line sensor of the reference color is moved to the reference line position of another color that does not have the abnormal pixel in the image data of each color, the document transport unit transports the document, the reading section have rows reading an original,
The reading unit performs reading while moving the position of the reading line of the reference color from the reference line position of the reference color to the reference line position of the color adjacent to the reference color,
The detection unit includes an undetected read line that is a line in which no abnormal pixel is present in the image data of each color between the reference line position of the reference color and the reference line position of a color adjacent to the reference color. Check if there is,
When there is the abnormal pixel in the image data of each color even if the position of the reference color reading line is moved to the reference line position of any color,
After the moving unit moves the optical unit so that the position of the reference color reading line becomes the position of the non-detection reading line, the document conveying unit conveys the document, and the reading unit reads the document. the image reading apparatus according to claim 1, wherein the performing. While performing the movement process so that the position of the reference color reading line becomes the reference line position of a color that is not adjacent to the reference color, the reading unit performs reading,
The detection unit checks whether or not there is the non-detection reading line between the reference line position of the color before movement and the reference line position of the color after movement,
Even if the position of the reference color reading line is moved to the reference line position of any color, the abnormal pixel exists in the image data of each color, and the reference line position of the reference color is changed to the reference color. When there is no undetected read line between the adjacent line and the reference line position,
After the moving unit moves the optical unit so that the position of the non-detection reading line confirmed between the reference line positions of colors other than the reference color is reached, the document conveying unit conveys the document. and, wherein the reading unit includes an image reading apparatus according to claim 1, wherein the reading of the manuscript. The moving unit moves the optical unit to a reference reading position where the position of the reading line of each line sensor becomes the reference line position before starting reading of the document,
The detection unit detects whether or not the abnormal pixel is present in the image data of each color obtained by the reading unit reading at the reference reading position;
When the abnormal pixel is present in the image data of each color, the moving unit performs the moving process,
3. The image reading apparatus according to claim 1, wherein when there is no abnormal pixel in the image data of each color, the document conveying unit conveys the document in the state of the reference reading position, and the reading unit reads the document. The image reading apparatus described in 1. An image forming apparatus comprising an image reading apparatus according to any one of claims 1 to 3.

Images