JP5622657B2 - 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 over a contact glass. Here, dirt such as dust and glue may adhere to the contact glass. When dirt is attached, the amount of light received by the light receiving element of the image sensor at a position corresponding to the attached portion decreases. For this reason, in the image data, streaks (black streaks) darker than surrounding pixels occur along the sheet conveyance 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 can provide 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.

  An object of the present invention is to eliminate the occurrence of black streaks from the first document reading without complicated operations and processing in view of the above-described problems of the prior art.

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, Including a monochrome reading line sensor and a color reading line sensor for a plurality of colors , an image sensor for reading a line in the main scanning direction, and irradiating light along the main scanning direction to a document passing through the contact glass; An optical unit that guides reflected light from a document to the image sensor, a moving unit that moves the optical unit in a sub-scanning direction, a generation unit that generates image data based on the output of the image sensor, and an image data A streak detection unit that detects abnormal pixels that generate black streaks, position information of the optical unit in the previous reading, and the previous information corresponding to the position information A storage unit for storing for each color whether information indicating the presence or absence of the abnormal pixel at up saw includes a reading control unit, the previous start reading the document, the reading control unit stored in said storage unit The position information and the presence / absence information in the previous reading are confirmed, and the abnormal pixel is detected in the image data of any color at the position of the optical unit in the previous reading based on the presence / absence information of each color. check whether the said moving unit, based on the presence information, if there is the abnormal pixel in either the color image data of the previous reading is the same position as the previous document reading, the last If the abnormal pixel is present in the image data of any color during reading, the optical unit is moved to a pre-conveyance position that is different from the previous document reading, and the reading control unit reads the document to be executed from now on. Black and white If the reading is not in black and white, the pre-conveyance position is set as the original reading execution position, and the original is read while the optical unit is fixed at the pre-conveyance position. When reading in black and white, the optical unit emits light toward the contact glass at the pre-conveyance position, the image sensor performs reading, and the streak detection unit is image data at the pre-conveyance position. The moving unit detects the presence or absence of the abnormal pixel, and the moving unit does not move the optical unit when starting document reading when the streak detecting unit does not detect the presence of the abnormal pixel. When the presence of the image is detected, the optical unit is moved to a position different from the pre-conveyance position before the document reading is started.

  According to this configuration, based on the presence / absence information, the moving unit is in the same position as the previous document reading if there is no abnormal pixel in the previous reading, and is different from the previous document reading if there is an abnormal pixel in the previous reading. The optical unit is moved to the pre-conveyance position. As a result, the line position (reading line position) at which the image sensor reads in the contact glass can be adjusted to a position where there is a high possibility of no flaws or dirt that cause streaks. Therefore, the black streak occurrence probability in the read image data can be lowered.

  Further, the moving unit does not move the optical unit when starting the document reading when the streak detecting unit does not detect the presence of the abnormal pixel, and the optical unit before starting the document reading when the streak detecting unit detects the presence of the abnormal pixel. Is moved to a position different from the pre-conveyance position. As a result, before starting the reading of the document, the presence of scratches or dirt on the reading line on the contact glass in 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 on the contact glass of the image sensor can be adjusted to a position where no streaking occurs by reading the line once before starting the document reading, and the black streak from the first sheet of the document can be adjusted. Can be eliminated.

  According to a second aspect of the present invention, in the first aspect of the invention, the image sensor includes a monochrome reading line sensor and a color reading line sensor for a plurality of colors. When the streak detecting unit detects the presence of the abnormal pixel in the black and white image data at the pre-conveyance position, the black and white reading line sensor reads the reading line on the contact glass before starting the document reading. The optical unit is moved so that the position of the reading line is the position of the reading line on the contact glass that has been read by the color reading line sensor that has been detected as having no abnormal pixels.

  According to this configuration, when the original is read in black and white, the moving unit detects the presence of abnormal pixels in the black and white image data at the pre-conveyance position and the black and white reading line before starting the original reading. Position the optical unit so that the position of the reading line on the contact glass that the sensor reads is the position of the reading line on the contact glass that was read by the color reading line sensor that has been detected as having no abnormal pixels. Move. As a result, if there are scratches or stains that cause streaks in the reading line on the contact glass read by the black and white line sensor, the line position for scanning in the black contact glass is abnormal pixels (scratches or stains), etc. It is adjusted to the position of the reading line of the color (line sensor) detected as being absent. Therefore, the position of the reading line on the contact glass of the line sensor for black-and-white reading can be adjusted to a position free from dirt and scratches by reading the line once before starting the document reading. It is possible to prevent the generation of streaks when reading a document.

  According to a third aspect of the present invention, in the second aspect of the present invention, when the moving unit detects the presence of the abnormal pixel from the image data of all colors at the pre-conveyance position, the moving unit Before starting the reading, the optical unit is moved so that the position of the reading line on the contact glass, which is read by the monochrome reading line sensor, deviates from the position of the reading line of any color at the pre-conveyance position. It was.

  According to this configuration, the moving unit is a contact that is read by the monochrome reading line sensor before starting the document reading when the streak detecting unit detects the presence of the abnormal pixel in the image data of all colors at the pre-conveyance position. The optical unit is moved so that the position of the reading line on the glass deviates from the position of the reading line of any color at the pre-conveyance position. As a result, when there are dirt or scratches in the reading lines of all color contact glasses, black streaks occur regardless of the position of the reading line of the monochrome reading line sensor to the position of the reading line of any color. In other words, it is possible to intentionally move the optical unit to a position where the possibility of occurrence of a streak is low, thereby reducing the streak occurrence probability in the black reading line.

Further, the interval between each color reading lines in the contact glass where the black and white reading line sensor and a color reading line sensor reads, set to be constant intervals, to the mobile unit, before starting document reading When moving the optical unit from the pre-conveyance position, the optical unit may be moved at the predetermined interval .

  According to this configuration, the moving unit moves the optical unit at a constant interval when moving the optical unit from the pre-conveyance position before starting the document reading. As a result, the position of the reading line on the contact glass of the black-and-white reading line sensor can be shifted to a position where there is no dirt or scratches by moving the optical unit at regular intervals.

Further , it is conceivable to store the position information of the optical unit and the presence / absence information at the completion of reading the last page in the previous reading in the storage unit .

  According to this configuration, the position information and presence / absence information of the optical unit when the reading of the last page in the previous reading is completed are stored. Accordingly, it is possible to set a pre-conveyance position that is highly likely to cause no streak in the reading line while narrowing down data to be stored in the storage unit.

Further, in the storage unit, the abnormal pixel is allowed to store the abnormality position information indicating the position of the optical unit upon being detected, the mobile unit, on the basis of the abnormality position information, not detected the abnormal pixel It is conceivable to move the optical unit so that the position becomes the pre-conveyance position .

  According to this configuration, the moving unit moves the optical unit based on the abnormal position information so that the position where no abnormal pixel is detected becomes the pre-conveyance position. Accordingly, it is possible to set a pre-conveyance position where there is a high possibility that no streak appears on the reading line.

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, it is possible to perform printing based on image data in which the generation of streaks is extremely suppressed from the first document by only reading the line once before starting the document reading. Therefore, it is possible to provide a high-quality image forming apparatus in which the generation of streaks is suppressed.

  According to the present invention, an image reading apparatus that greatly reduces the probability of occurrence of streaks when reading the first document without complicated operations and processing and outputs image data without black streaks from the first document. In addition, it is possible to provide an image forming apparatus having no streaks on 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 line for reading with the contact reading glass for conveyance reading of each line sensor. 10 is a flowchart illustrating an example of a control flow for storing presence / absence of abnormal pixels during document reading. 6 is a flowchart showing an example of a flow of black stripe generation avoidance control at the time of starting document reading.

  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 schematic front sectional view showing a schematic configuration of the multifunction machine 200.

  As illustrated in FIG. 1, the multifunction peripheral 200 according to the present embodiment includes 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 or the placement reading contact glass 12 and generates image data by the image sensor 15 based on the reflected light, and the image reading unit. 1 includes a document conveying unit 2 that opens and closes in the vertical direction with respect to the image reading unit 1 and conveys the 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 multifunction device 200, is a touch panel type, and includes a liquid crystal display unit 30 that receives 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. In addition, 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 path 4b, an image forming unit 5a, an intermediate transfer unit 5b, a fixing unit 5c, and the like inside the main body. The plurality of paper feed units 4a in the main body of the multi-function device 200 are each of a size (for example, A type, B type paper such as A4, B4, etc.), various papers (for example, copy paper, recycled paper, cardboard, OHP sheet) Etc.). Each paper feed unit 4a includes a paper feed roller 41 that is rotationally driven. During printing, the paper feed roller 41 of one of the paper feed units 4a rotates and feeds the paper one by one into the transport path 4b.

  The transport path 4b is a path for transporting paper within the apparatus. Then, on the conveyance path 4b, a guide plate for guiding the sheet, a pair of conveyance rollers 42 that are rotationally driven during conveyance of the sheet (in FIG. 1, a total of three of 42a, 42b, and 42c from the top) are conveyed. 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 unit 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 portion 5b receives the primary transfer of the toner image from each image forming unit 50 and performs the secondary transfer on 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 of the photosensitive drums corresponding to the primary transfer rollers 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 drive roller 54, the primary transfer rollers 52Bk to 52M, and the like. 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 applied with a predetermined voltage. The image is transferred to the sheet by the secondary 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 section 2 automatically and continuously conveys the document 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. 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 in 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 for reading 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 out the documents one by one to the document transport path 23.

  The document sent out 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 places the document on the placement reading contact glass 12 with the document transport unit 2 lifted and the reading surface facing downward.

  In addition, as shown in FIG. 2, a first moving frame 61 (corresponding to an optical unit), a second moving frame 62 (corresponding to an optical unit), and a wire 63 (corresponding to a moving unit) are provided in the housing of the image reading unit 1. The take-up drum 64 (corresponding to the moving unit), the lens 14, and the light applied to the original are incident, and an image sensor 15 for reading the original for each line and generating image data is disposed.

  The first moving frame 61 supports a light source 610 that irradiates light on the document along the main scanning direction and a first mirror 611 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 the second mirror 622 on the upper side and the third mirror 623 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 a shape that extends in the main scanning direction (the direction perpendicular to the plane 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 uses a winding motor 65 (corresponding to a moving unit, see FIG. 4) as a drive source. 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 optical path length from the light source 610 to the image sensor 15 due to the position of each moving frame, a plurality of pulleys (not shown) are provided inside the image reading unit 1. 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 strikes 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. The image sensor 15 includes, for example, a line sensor 7 in which a plurality of light receiving elements R (photoelectric conversion elements) are arranged in a line (details will be described later).

  Then, each light receiving element R (each pixel) of the image sensor 15 converts it into an analog electrical signal according to the level of reflected light (the amount of received light). 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, in the case of reading a document conveyed by the document conveying unit 2, the winding motor 65 is driven, and the first moving frame 61 and the second moving frame 62 are fixed at positions below the conveying and 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 8 that controls the entire multifunction device 200. The main control unit 8 is provided with a CPU 81 as a central processing unit. In addition, a storage device 82 composed of nonvolatile and volatile memories such as a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), and a flash ROM is provided in the main control unit 8 (main control unit). 8 may be provided).

  The storage device 82 stores programs, data, and the like for controlling the multifunction device 200. The main control unit 8 uses the program and data stored in the storage unit 16 to control each unit and perform printing. The main control unit 8 is a main control unit that performs overall control, communication control, and image processing, and engine control that controls ON / OFF of a toner image formation control, a motor that rotates various rotating bodies, and the like to control printing. A plurality of types may be provided by dividing each function such as a section.

  The main control unit 8 is provided with an image processing unit 83 that performs image processing based on image data output from the image reading apparatus 100. For example, the image processing unit 83 includes an ASIC, an image memory, and the like, and can perform various image processing such as density conversion processing, enlargement / reduction processing, rotation processing, image data compression / decompression processing, and the like. Note that the image processing unit 83 can perform other image processing (for example, frame erasing processing) and the like, but a description thereof is omitted because it can perform known image processing.

  The main control unit 8 is connected to the sheet feeding unit 4a, the conveyance path 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 8 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 8. The main control unit 8 is also connected to the image reading apparatus 100. For example, when executing copying, the main control unit 8 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) is performed (copy).

  The multifunction device 200 includes a communication unit 84 as an external communication interface. The communication unit 84 communicates with, for example, an external computer 300 (for example, a personal computer or server) or the FAX apparatus 400 via a network, a cable, or a public line. The communication unit 84 includes, for example, a plurality of connectors for connecting to a network, a cable, or a public line, and a communication circuit such as a communication control controller, a chip, and a modem. With this communication unit 84, 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, the image data obtained by reading the document by the image reading unit 1 can be transmitted to the external computer 300 or the FAX apparatus 400 (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 conveyance unit 2 uses a copy function and a transmission function, when reading a document, the document placed on the document tray 21 is directed toward the conveyance reading contact glass 11 one by one continuously and automatically. Transport to. The document transport unit 2 is sometimes 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 8 and the reading control unit 10 described above. The document conveyance control unit 20 is, for example, 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 8 and the like, and receives an instruction to start document conveyance from the main control unit 8 and the like, and controls the operation of the document conveyance unit 2. For example, when a document reading instruction is issued from the main control unit 8, 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 8 and the document conveyance control unit 20 described above. The reading control unit 10 receives an instruction and signal from the main control unit 8 and reads a document. The reading control unit 10 is a substrate including a CPU and an ASIC as a processing device.

  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 an original, an instruction from the main control unit 8 is received, and the reading control unit 10 Operation control of each member in the reading unit 1 and transmission control of image data obtained by reading to the main control unit 8 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.

  For example, the winding motor 65 moves the first moving frame 61 by one pixel per pulse (for example, about 0.0423 mm for 600 dpi). Thereby, the position of the reading line of the image sensor 15 in the conveyance reading contact glass 11 can be shifted in units of one pixel.

  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, and an instruction from the main control unit 8. Accordingly, an instruction to read the document, in other words, an instruction to drive is given.

  The lighting circuit 612 is a circuit that lights 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), the lighting circuit 612 is, for example, an inverter. Then, the reading control unit 10 causes the lighting circuit 612 to light the light source 610 based on the reading start instruction from the main control unit 8.

  The image sensor 15 receives the light irradiated on 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 includes a line sensor 7Bk / W (for black and white), a line sensor 7B (for blue), a line sensor 7G (for green), and a line sensor 7R (for red) in this order. Provided. Note that the arrangement and order of the colors may be interchanged. In the following description, reference numerals indicating the distinction between Bk / W, B, G, and R colors are omitted, and the line sensor 7 may be simply referred to. 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 whether to read a document in black and white (monochrome mode) or to read a document in color (color mode) on the operation panel 3. Therefore, the operation panel 3 functions as an input unit that receives color settings (black and white mode and color mode selection) for document reading.

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

  On the other hand, when reading in color (color mode), the original is read using the line sensor 7B (for blue), the line sensor 7G (for green), and the line sensor 7R (for red). In other words, when reading in black and white, R, G, and B image data are generated based on the outputs of the line sensor 7B (for blue), the line sensor 7G (for green), and the line sensor 7R (for red). The Note that the image processing unit 83 of the main control unit 8 can generate luminance information (information indicating black and white) from the 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 R (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 / W is not provided with a color separation filter.

  5, for example, the distance D1 between the line sensor 7Bk / W and the line sensor 7B, the distance D1 between the line sensor 7B and the line sensor 7G, and the distance D1 between the line sensor 7G and the line sensor 7R are made equal. The

  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, the range of movement from the home position is that the first moving frame 61 is positioned below the conveyance reading contact glass 11 (the reading line of the image sensor 15 is positioned on the conveyance reading contact glass 11). Information indicating the range to be stored) is stored in the storage unit 16. When the original is conveyed and read (when the original passing through the conveyance reading contact glass 11 is read), the reading control unit 10 determines that the reading line of each line sensor 7 in the image sensor 15 is 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 reading the document placed on the placement reading contact glass 12, the reading control unit 10 operates the winding motor 65 to move the first moving frame 61 and the second moving frame 62 from the home position. The placement reading contact glass 12 is moved from the left end toward the right end.

  The A / D converter 17 receives the analog electrical signal of each pixel obtained by the image sensor 15 and performs quantization to convert it into a digital signal to generate 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 this embodiment, an example in which the correction processing unit 18 is provided in the image reading unit 1 and the image processing unit 83 is provided in the main control unit 8 will be described. For example, only one image processing unit 83 is provided on the main body side. Only one image processing unit 83 may be configured to perform the processing of the correction processing unit 18 and the processing of the image processing unit 83 in this description.

  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 19 and then transferred to the main control unit 8. Further, when performing printing, the main control unit 8 transmits the image data after the image processing by the image processing unit 83 to the exposure device 51, and performs printing (toner image formation) based on the image data. Alternatively, when performing the transmission, the main control unit 8 transmits the image data after the image processing by the image processing unit 83 to the communication unit 84 to transmit to the external computer 300 or the like.

  The image reading unit 1 is provided with a streak detecting unit 9. The stripe detection unit 9 generates black stripes 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). An abnormal pixel is detected. For example, the streak detecting unit 9 is used when the image sensor 15 (each line sensor 7) reads the white plate 27 before the original passes through the conveyance reading contact glass 11 or after the original passes through the conveyance reading contact glass 11. It is detected whether or not a streak is generated based on the image data of each color. Details of the detection of the streaks will be described later.

(The position of the reading line on the 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 a line where reading is performed by 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. In the present embodiment, the position of the line (reading line) 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 described above. The black and white reading line LBk, the blue reading line LB, the green reading line LG, and the red reading line LR are sequentially arranged.

  In this embodiment, the original is read at 600 dpi. Therefore, the length of one side of one pixel in the original is 42.3 μm (23.4 mm (1 inch) ÷ 600). This pixel corresponds to each light receiving element R of each line sensor 7. Pixels having a side of 42.3 μm are reduced by the lens 14 and converted to the pitch of the light receiving elements R. The interval D2 between the reading lines for each color is, for example, 12 times one pixel, that is, 42.3 [μm] × 12≈0.5 [mm]. Therefore, the distance D1 between the 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.

(Outline of muscle detection)
Next, an outline of muscle detection in this embodiment will be described with reference to FIGS. 4 and 6.

  As shown in FIG. 4, the image reading unit 1 according to the present embodiment is checked for the presence or absence of scratches or dirt that cause black streaks in the reading lines of the conveyance reading contact glass 11 of each line sensor 7. A muscle detection unit 9 for detection is provided.

  The streak detection unit 9 determines the presence or absence of abnormal pixels that cause black streaks based on the image data of each line sensor 7 when the white plate 27 is read. Originally, since the white plate 27 is read, the pixel value of each pixel in the image data of one main scanning line should be a value indicating white. However, if the conveyance reading contact glass 11 has a flaw, the pixel value of the pixel at the position where the flaw is read in the reading line becomes darker (gray or black) than the portion without the flaw. Further, even if dirt, dust, dust, glue, ink, etc. are adhered to the contact glass 11 for carrying reading, the pixel value of the pixel at the position where the dirt, etc. in the reading line is read is compared with that of the non-attached part. It becomes darker (gray or black).

  Therefore, the streak detecting unit 9 has a darker (darker, blacker) direction than the predetermined threshold in the image data (for example, for one main scanning line) of each line sensor 7 when the white plate 27 is read. It is confirmed whether or not there is a pixel having a pixel value. This predetermined threshold is stored in the storage unit 16 in the image reading unit 1, for example. Then, the streak detection unit 9 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 addition, 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 streak detection unit 9 reads the image data obtained by each 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.

  The streak detection unit 9 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 streak detection unit 9 notifies the reading control unit 10 of a color (line sensor 7) in which scratches and dirt are present on the reading line in the conveyance reading contact glass 11. Upon receiving this notification, as indicated by a broken line in FIG. 5, the reading control unit 10 causes the position of the reading line on the conveyance reading contact glass 11 of each line sensor 7 to be a position free from scratches, dirt, dust, and the like. Further, the winding motor 65 is operated to move each moving frame.

  For example, the reading control unit 10 moves the first moving frame 61 in units of a reading line interval D2 for each color (in this embodiment, 12 pixels). In this case, the reading control unit 10 gives 12 pulses to the winding motor 65, and moves the first moving frame 61 by 12 pixels so as to make the position of the reading line avoid scratches and dirt.

(Flow of black line avoidance control)
Next, an example of a control flow for avoiding black streak generation in the image reading apparatus 100 according to the present embodiment will be described with reference to FIGS. FIG. 7 is a flowchart illustrating an example of a control flow for storing presence / absence of abnormal pixels during document reading. FIG. 8 is a flowchart showing an example of the flow of black stripe generation avoidance control at the start of document reading.

  First, in the image reading apparatus 100 (reading control unit 10) according to the present embodiment, when the position of the first moving frame 61 at the time of the previous document reading, abnormal pixels that generate black streaks are included in the image data of each color. Presence / absence information indicating whether or not is stored in association with the position information of the first moving frame 61. 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.

  Therefore, a flow of storage control of presence / absence information associated with position information of the first moving frame 61 at the time of document reading 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 of FIG. 7 is a point in time when document reading using the document conveyance unit 2 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 # 1). 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 # 1), the reading control unit 10 continues to wait for a notification from the document conveyance control unit 20 (step # 1 loop). 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 # 1), the reading control unit 10 causes the image sensor 15 to read the white plate 27 after the document passes without moving the first moving frame 61. (Step # 2). 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.

  Then, the streak detection unit 9 determines whether or not there is an abnormal pixel that generates a streak in the image data for each color (for example, image data for one main scanning line) generated based on the output of the line sensor 7 for each color. (Step # 3).

  Then, the reading control unit 10 associates each color with 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) based on the detection result of the muscle detection unit 9. Presence / absence information indicating the presence / absence of abnormal pixels is stored in the storage unit 16 (step # 4).

  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. 8, the flow of black stripe generation avoidance control at the start of document reading will be described. The start in FIG. 8 is when the main control unit 8 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 8 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, 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 # 11). Then, based on the presence / absence information, the reading control unit 10 confirms whether or not an abnormal pixel is detected in the image data of any color at the position of the first moving frame 61 in the previous reading (step #). 12).

  If there is no abnormal pixel (No in step # 12), the reading control unit 10 rotates the winding motor 65 based on the position information in the previous reading, and sets the position in the previous reading as the pre-conveyance position. The first moving frame 61 is moved (step # 13).

  On the other hand, if there is an abnormal pixel (Yes in step # 12) and black streak is likely to occur, the reading control unit 10 moves the first moving frame 61 using a position different from the previous reading as a pre-conveyance position ( Step # 14). 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 # 14, 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 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.

  Then, the reading control unit 10 confirms whether or not the original to be executed is to be read in black and white (reading in the black and white mode) (step # 15). If the reading is not in black and white (No in step # 15 if the reading is in color), the reading line should be set so that abnormal pixels do not occur in the three colors of blue, green, and red in a short time. Since it is difficult to find and set the position, the reading control unit 10 sets the pre-conveyance position as the original reading execution position (step # 16). In other words, the reading control unit 10 causes the original to be read while the first moving frame 61 is fixed at the pre-conveyance position in the color mode.

  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, at the time of color reading, in step # 16, the reading control unit 10 does not set the pre-conveyance position as the original reading execution position, and at least the R, G, B line sensors based on the abnormal position information. So that the abnormal pixel is not detected in the read image data (the position of the reading line on the conveyance reading contact glass 11 is the position where there is no scratch or dirt in the three colors R, G, B). The first moving frame 61 may be moved to the position of the first moving frame 61 in the color mode. Then, this control is finished, and the document conveying unit 2 actually starts document conveyance, and the image reading unit 1 starts reading the document (END).

  On the other hand, if the reading is in black and white (Yes in step # 15), the reading control unit 10 turns on the light source 610 in a state where the first moving frame 61 is fixed at the pre-conveyance position, and the entire image sensor 15 is turned on. The line sensor 7 is caused to read the white plate 27 (step # 17). Then, the streak detection unit 9 detects abnormal pixels that generate black streaks on the line in the main scanning direction based on the image data of each color (step # 18).

  The reading control unit 10 receives the detection result of the streak detecting unit 9 and confirms whether or not the abnormal pixel is included in the image data of the monochrome line sensor 7Bk / W (step # 19). In other words, the reading control unit 10 checks whether there are any scratches or dirt on the reading line on the conveyance reading contact glass 11 of the line sensor 7Bk / W (step # 19).

  If the abnormal pixel is not included in the image data of the monochrome line sensor 7Bk / W (No in step # 19), the reading control unit 10 sets the pre-conveyance position as the original reading execution position (step #). 20). In other words, the reading control unit 10 causes the original to be read using the monochrome line sensor 7Bk / W 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 monochrome line sensor 7Bk / W (Yes in step # 19 if black streak occurs), the reading control unit 10 detects the streak detection unit 9. Based on the result, it is confirmed whether or not an abnormal pixel is included in the image data of the color reading line sensor 7 (line sensor 7B, line sensor 7G, line sensor 7R) (step # 21).

  If there is a color that does not include abnormal pixels in the image data (No in step # 21), the reading control unit 10 reads the reading line on the conveyance reading contact glass 11 of a color that does not include abnormal pixels. The winding motor 65 is controlled to move the first moving frame 61 so that the position of is the position of the reading line of the monochrome line sensor 7Bk / W (step # 22).

  On the other hand, if an abnormal pixel is included in the image data for all colors (Yes in step # 21), 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 # 23). For example, the reading control unit 10 determines that the position of the reading line on the transport reading contact glass 11 of each color after movement is the position of the reading line on the transport reading contact glass 11 of any color at the pre-transport position. The first moving frame 61 is moved to a position that does not overlap. 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 # 22 and step # 23, 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 # 24). 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 is provided so as to sandwich 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. White plate 27, image sensor 15 that reads lines in the main scanning direction, and optical that irradiates the original passing through the contact glass along the main scanning direction and guides reflected light from the original to image sensor 15. Output unit (first moving frame 61, second moving frame 62), moving unit (winding motor 65, winding drum 64, wire 63, etc.) that moves the optical unit in the sub-scanning direction, and output of image sensor 15. A generation unit (A / D conversion unit 17) that generates image data, a stripe detection unit 9 that detects abnormal pixels that generate black stripes based on the image data, and a previous reading. And a storage unit 16 for storing presence / absence information indicating the presence / absence of abnormal pixels in the previous reading in correspondence with the position information. Based on the presence / absence information, if there is no abnormal pixel in the previous reading, the optical unit is at the same position as the previous original reading, and if there is an abnormal pixel in the previous reading, the optical unit is at a position before conveyance that is different from the previous original reading. The optical unit emits light toward the contact glass at the pre-conveyance position, the image sensor 15 performs reading, and the streak detection unit 9 detects the presence or absence of abnormal pixels in the image data at the pre-conveyance position. The moving unit does not move the optical unit when starting the document reading when the streak detecting unit 9 does not detect the presence of the abnormal pixel, and before the document reading starts when the streak detecting unit 9 detects the presence of the abnormal pixel. Optics Moving the feeding position before a different position.

  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. Thus, the line position (reading line position) at which the image sensor 15 reads in the contact glass (conveyance reading contact glass 11) is adjusted to a position where there is a high possibility of no flaws or dirt that cause streaks. be able to. Therefore, the black streak occurrence probability in the read image data can be lowered. Also, before starting to read the document, check for any scratches or dirt on the reading line on the contact glass at the pre-conveyance position in advance. If there is no risk of black streaking, start reading the document at the pre-conveyance position. If there is a risk of black streaking, the optical unit is moved. Therefore, the position of the reading line 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 streaks can be eliminated.

  The image sensor 15 includes a black and white reading line sensor 7 and a color reading line sensor 7 for a plurality of colors. When reading an original in black and white, the moving unit (winding motor 65, winding drum 64, wire 63, etc.) ) Is a contact glass (conveying reading contact) that is read by the black and white reading line sensor 7 before reading the original when the streak detecting unit 9 detects the presence of abnormal pixels in the black and white image data at the pre-conveying position. The optical section (first movement) is such that the position of the reading line on the glass 11) is the position of the reading line on the contact glass that has been read by the color reading line sensor 7 of the color detected that there is no abnormal pixel. The frame 61 and the second moving frame 62) are moved.

  As a result, if there are scratches or stains that cause streaks in the reading line on the contact glass (conveyance reading contact glass 11) read by the black and white line sensor 7, the position of the black and white line in the contact glass becomes an abnormal pixel. The color (line sensor 7) detected when there is no (scratch or dirt) is adjusted to the position of the reading line. Accordingly, the position of the reading line on the contact glass of the line sensor 7 for black and white reading can be adjusted to a position free from dirt and scratches by only reading the line once before starting the document reading. It is possible to prevent the generation of streaks when reading originals.

  Further, the moving unit (winding motor 65, winding drum 64, wire 63, etc.) is arranged before the start of document reading when the streak detecting unit 9 detects the presence of abnormal pixels in all color image data at the pre-conveyance position. In addition, the optical unit (the optical unit (so that the position of the reading line on the contact glass (conveying reading contact glass 11) on which the monochrome reading line sensor 7 reads) deviates from the position of the reading line of any color at the pre-conveying position. The first moving frame 61 and the second moving frame 62) are moved. As a result, when there are dirt or scratches in the reading lines of all color contact glasses, black streaks occur regardless of the position of the reading line of the monochrome reading line sensor 7 in any color reading line position. Therefore, the optical unit (the first moving frame 61 and the second moving frame 62) is intentionally moved to a position where the possibility of occurrence of a streak is low, and the streak occurrence probability in the black reading line is lowered. Can do.

  Further, the interval between the reading lines of each color on the contact glass (conveying reading contact glass 11) read by the monochrome reading line sensor 7 and the color reading line sensor 7 is set to be a constant interval, and the moving unit When the optical unit (first moving frame 61, second moving frame 62) is moved from the pre-conveyance position before starting document reading, the take-up motor 65, the take-up drum 64, the wire 63, and the like are moved at regular intervals. Move the optical part. As a result, the position of the reading line on the contact glass of the monochrome reading line sensor 7 can be shifted to a position where there is no dirt or scratches by moving the optical unit at a constant interval.

  Further, the storage unit 16 stores position information and presence / absence information of the optical unit (the first moving frame 61 and the second moving frame 62) when the last page is read in the previous reading. Accordingly, it is possible to set a pre-conveyance position that is highly likely to cause no streak in the reading line while narrowing down data to be stored in the storage unit 16.

  The storage unit 16 stores abnormal position information indicating the position of the optical unit (the first moving frame 61 and the second moving frame 62) when an abnormal pixel is detected, and the moving unit (the winding motor 65, the winding motor 65). The take-up drum 64, the wire 63, and the like) move the optical unit based on the abnormal position information so that the position where no abnormal pixel is detected becomes the pre-conveyance position. Accordingly, it is possible to set a pre-conveyance position where there is a high possibility that no streak appears on the reading line.

  Further, the image forming apparatus (for example, the multifunction device 200) includes the image reading apparatus 100 according to the present embodiment. As a result, printing can be performed based on image data in which the generation of streaks is extremely suppressed from the first document by reading the line once before starting the document reading. Therefore, it is possible to provide a high-quality image forming apparatus in which the generation of streaks is suppressed.

  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.

DESCRIPTION OF SYMBOLS 1 Image reading part 11 Conveyance reading contact glass 15 Image sensor 16 Storage part 17 A / D conversion part (generation part) 2 Document conveying part 27 White plate 61 1st moving frame (optical part)
62 Second moving frame (optical part) 63 Wire (moving part)
64 Winding drum (moving part) 65 Winding motor (moving part)
7 (7Bk / W, 7B, 7G, 7R) Line sensor 7Bk / W Line sensor (Line sensor for monochrome reading)
7B Line sensor (color reading line sensor)
7G line sensor (line sensor for color reading)
7R line sensor (line sensor for color reading)
9 Streak Detection Unit 100 Image Reading Device 200 Multifunction Device (Image Forming Device) D2 Interval (Constant Interval)
LBk reading line (black and white) LB reading line (blue)
LG Reading line (Green) LR Reading line (Red)

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 that includes a monochrome reading line sensor and a color reading line sensor for a plurality of colors , and reads a line in the main scanning direction;
An optical unit that irradiates light along a main scanning direction to a document passing through the contact glass and guides reflected light from the document to the image sensor;
A moving unit that moves the optical unit in the sub-scanning direction;
A generating unit that generates image data based on the output of the image sensor;
A streak detector that detects abnormal pixels that generate black streaks based on image data;
And position information of the optical portion of the previous original reading, a storage unit for the presence information indicating the presence or absence of the abnormal pixel in the previous document reading in correspondence with the positional information stored for each color,
A reading control unit ,
Before starting to scan the document,
The reading control unit confirms the position information and the presence / absence information in the previous reading stored in the storage unit, and based on the presence / absence information of each color, the position of the optical unit in the previous reading Check whether the abnormal pixel is detected in the image data of any color,
Based on the presence / absence information, the moving unit is in the same position as the previous document reading if there is no abnormal pixel in the image data of any color in the previous reading, and the image of any color in the previous reading. If the abnormal pixel is present in the data, move the optical unit to a pre-conveyance position that is different from the previous document reading,
The reading control unit confirms whether or not the original to be executed is to be read in black and white, and when the reading is not in black and white, sets the pre-conveyance position as the original reading execution position, and sets the optical unit to the conveyance Scan the document with the front position fixed,
On the other hand, when reading in black and white, the optical unit irradiates light toward the contact glass at the pre-conveyance position, the image sensor performs reading, and the streak detection unit detects an image at the pre-conveyance position. The presence / absence of the abnormal pixel in the data is detected, and the moving unit does not move the optical unit at the start of document reading when the streak detecting unit does not detect the presence of the abnormal pixel. An image reading apparatus, wherein when the presence of an abnormal pixel is detected, the optical unit is moved to a position different from the pre-conveyance position before starting document reading. If you read a document in black and white,
The moving unit is the contact glass that is read by the black and white reading line sensor before the document reading is started when the streak detecting unit detects the presence of the abnormal pixel in the black and white image data at the pre-conveyance position. The optical unit is moved so that the position of the reading line is the position of the reading line on the contact glass that has been read by the color reading line sensor of the color detected that there is no abnormal pixel. The image reading apparatus according to claim 1.   The moving unit includes the contact glass that is read by a black and white reading line sensor before starting to read a document when the streak detecting unit detects the presence of the abnormal pixel in all color image data at the pre-conveyance position. 3. The image reading apparatus according to claim 2, wherein the optical unit is moved so that the position of the reading line at the position deviates from the position of the reading line of any color at the pre-conveyance position. An image forming apparatus comprising an image reading apparatus according to any one of claims 1 to 3.

Images