JP2013042251A - Image reader and image forming apparatus including the image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of reading a correct image when an image is read from any kinds of manuscripts, and also to provide an image forming apparatus including the image reader.SOLUTION: An image reader includes a control part 20, an interpolation part 21, a CIS (contact image sensor) unit 50, and a solenoid 231. The control part 20 reads pixel information from a manuscript, while moving the CIS unit 50 placed at a first position in a main scanning direction from a start position to an end position in a sub-scanning direction (S12). The control part 20 allows a current to flow in the solenoid 231 and moves the CIS unit 50 to a second position (S14), and reads pixel information from a manuscript, while moving the CIS unit 50 from a start position to an end position (S15). The control part 20 allows the interpolation part 21 to interpolate a missing pixel that has not been read at the first position with the use of pixel information which is extracted from the pixel information read at the second position and is applicable to the missing pixel (S18).

Description

  The present invention relates to a CIS (contact image sensor) type image reading apparatus and an image forming apparatus including the image reading apparatus.

  A CIS image reading apparatus includes a plurality of sensor substrates arranged in a line along the main scanning direction. Each of the plurality of sensor substrates has a predetermined number of image sensors. Each image sensor reads an image from a document as the plurality of sensor substrates move in a sub-scanning direction orthogonal to the main scanning direction. Since there is no image sensor at the joint between the sensor substrates, the pixel information of this portion cannot be read from the document, and there are missing pixels.

  In the image reading device described in Patent Document 1, the missing pixel is interpolated by estimating the missing pixel using pixel information (for example, density, luminance, etc.) of the two image sensors adjacent to the missing pixel. Image data is generated.

JP 2004-356933 A

  However, since the image reading apparatus of Patent Document 1 estimates the missing pixels using the pixel information of the two front and rear imaging elements, when an image image having a fine periodic pattern is read, the location where the missing pixels are interpolated Produces unnatural streaks.

  An object of the present invention is to provide an image reading apparatus or an image forming apparatus capable of accurately interpolating a missing pixel by re-reading a location corresponding to the missing pixel and re-reading a location corresponding to the missing pixel. That is.

  The image reading apparatus according to the present invention includes an image reading unit, a moving unit, a control unit, and an interpolation unit. The image reading unit includes a plurality of imaging elements arranged in a line in the main scanning direction, and the document is moved when the plurality of imaging elements move between the start position and the end position in the sub-scanning direction orthogonal to the main scanning direction. Read image from. The moving unit moves at least a plurality of image sensors to a first position or a second position separated by a predetermined distance in the main scanning direction. The control unit causes the image reading unit to move the plurality of imaging elements between the start position and the end position at each of the first position and the second position. The interpolation unit interpolates missing pixels based on the image read by the image reading unit at each of the first position and the second position.

  In this configuration, the control unit moves the plurality of image pickup elements located at the first position in the main scanning direction from the start position to the end position in the sub-scanning direction orthogonal to the main scanning direction, and each image pickup element moves from the document. Obtain pixel information. The control unit moves the plurality of image sensors to the second position separated from the first position by a predetermined distance along the main scanning direction, and moves the plurality of image sensors from the start position to the end position in the sub-scanning direction. Thus, pixel information is acquired from the document by each image sensor. The interpolation unit acquires pixel information corresponding to missing pixels that could not be acquired by each image sensor at either the first position or the second position from the pixel information acquired by each image sensor at the other. The interpolating unit interpolates the acquired pixel information into the pixel information acquired by each image sensor at either the first position or the second position.

  In this configuration, it is preferable that the predetermined distance is a distance equal to an integer multiple of 1 or more of a pitch for one pixel (missing pixel).

  Thereby, the control part can acquire easily the pixel information of the missing pixel in any one of a 1st position or a 2nd position from the pixel information which each image sensor acquired in the other.

  Further, the control unit moves the plurality of image sensors from the start position to the end position in the image reading unit in a state where the plurality of image sensors are positioned at the first position, and moves the plurality of image sensors to the second position in the moving unit. A configuration is preferable in which the image reading unit is moved from the end position to the start position after being moved.

  In this configuration, the control unit moves the plurality of image sensors located at the first position in the main scanning direction from the start position to the end position in the sub-scanning direction, and acquires pixel information from the document by each image sensor. The control unit moves the plurality of image sensors to a second position separated from the first position by a predetermined distance along the main scanning direction, and moves the plurality of image sensors from the end position to the start position in the sub-scanning direction. Thus, pixel information is acquired from the document by each image sensor. The interpolation unit interpolates the pixel information of the missing pixel at either the first position or the second position with the other pixel information.

  As a result, the control unit can read the image at the first position and then return the plurality of image pickup elements located at the end positions in the sub-scanning direction to the start position and acquire the pixel information. Can be shortened.

  Moreover, it is preferable that a moving part is comprised from the support member which supports a some image pick-up element, and the solenoid which moves a support member to a 1st position and a 2nd position by ON / OFF of electricity supply.

  Thereby, a plurality of image sensors can be moved to the first position and the second position in the main scanning direction with a simple configuration including the solenoid and the support member.

  An image forming apparatus according to the present invention includes the above-described image reading device and an image forming unit that performs image forming processing on a sheet based on an image read by the image reading device.

  As a result, by interpolating the pixel information of the missing pixels that could not be read the first time using the image information read the second time, an accurate image can be read regardless of the type of document read. Therefore, the original can be accurately copied.

  The image reading apparatus according to the present invention reads the image again, and interpolates the pixel information of the missing pixel that could not be read at the first time using the image information read at the second time. Even in this case, an accurate image can be read.

1 is a front view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2A is a cross-sectional view of the CIS unit in the image forming apparatus. FIG. 2B is a plan view of a sensor substrate included in the CIS unit. 2 is a block diagram illustrating some functions of the image forming apparatus. FIG. It is explanatory drawing of the moving mechanism which makes the sensor board | substrate movable in the image forming apparatus freely. FIG. 5A shows a state where the sensor substrate in the image forming apparatus is positioned at the first position. FIG. 5B shows a state where the sensor substrate is positioned at the second position. It is a schematic diagram which shows pixel arrangement | positioning of the image pick-up element arrange | positioned at the sensor board | substrate at the time of the movement from a 1st position to a 2nd position. It is a flowchart which shows the process at the time of image reading. It is a flowchart which shows the process at the time of image reading in another Example.

  As shown in FIG. 1, the image forming apparatus 100 includes a paper feeding unit 80, an image reading unit 90, and an image forming unit 110, and uses image data read from a document on a sheet as a recording medium by an electrophotographic method. A multicolor or single color image forming process is performed. Note that the image forming apparatus 100 may perform an image forming process based on image data input from an external apparatus.

  The image forming unit 110 includes an exposure unit 1, image forming units 10 </ b> A to 10 </ b> D, an intermediate transfer unit 60, a secondary transfer unit 30, and a fixing unit 70.

  The image forming unit 10A includes a developing device 2A, a photosensitive drum 3A, a cleaner unit 4A, and a charger 5A, and forms a black (Bk) image. The charger 5A uniformly charges the surface of the photosensitive drum 3A to a predetermined potential. The developing device 2A visualizes the electrostatic latent image formed on the photosensitive drum 3A by exposure of the exposure unit 1 into a Bk toner image. The cleaner unit 4A collects the toner remaining on the peripheral surface of the photosensitive drum 3A. The image forming units 10B to 10D are configured in the same manner as the image forming unit 10A, and respectively form cyan (C), magenta (M), and yellow (Y) toner images on the surfaces of the photosensitive drums 3B to 3D. .

  The exposure unit 1 is a laser scanning unit including optical system components such as a semiconductor laser, a polygon mirror, an fθ lens, and a reflection mirror. The exposure unit 1 exposes and scans the surfaces of the photosensitive drums 3A to 3D of the image forming units 10A to 10D along the axial direction with laser beams modulated by the image data of Bk, C, M, and Y, respectively. An electrostatic latent image is formed.

  The intermediate transfer unit 60 includes an intermediate transfer belt 61, a driving roller 62, a driven roller 63, primary transfer rollers 64A to 64D, and a cleaning unit 65. The intermediate transfer belt 61 is stretched around the driving roller 62 and the driven roller 63, and moves along a circulation path that passes through the image forming units 10D, 10C, 10B, and 10A in this order. Each of the primary transfer rollers 64A to 64D is disposed to face the photosensitive drums 3A to 3D with the intermediate transfer belt 61 interposed therebetween, and the toner images formed on the peripheral surfaces of the photosensitive drums 3A to 3D are intermediate transferred. Primary transfer is performed on the surface of the belt 61.

  During the color image forming process, the Y, M, C, and Bk toner images are sequentially superimposed and transferred onto the surface of the intermediate transfer belt 61 while the intermediate transfer belt 61 moves along the circulation path. During the monochrome image forming process, only the Bk toner image is transferred to the surface of the intermediate transfer belt 61 while the intermediate transfer belt 61 moves along the circulation path.

  The secondary transfer unit 30 includes a secondary transfer roller 31 and a secondary transfer belt 32. The secondary transfer belt 32 is stretched around a plurality of rollers and moves along a predetermined circulation path. The secondary transfer roller 31 is disposed so as to face the driving roller 62 with the secondary transfer belt 32 and the intermediate transfer belt 61 interposed therebetween. The secondary transfer unit 30 secondarily transfers the toner image on the surface of the intermediate transfer belt 61 to a sheet conveyed to a secondary transfer position between the intermediate transfer belt 61 and the secondary transfer belt 32. The toner remaining on the surface of the intermediate transfer belt 61 after the secondary transfer is collected by the cleaning unit 65.

  The fixing unit 70 heats and pressurizes the paper on which the toner image is transferred after passing through the secondary transfer position. The toner image transferred to the paper is firmly fixed on the surface of the paper. The paper that has passed through the fixing unit 70 is discharged to a paper discharge tray 91 disposed above the image forming unit 110.

  The paper feed unit 80 includes a paper feed cassette 81 and a manual feed tray 82. The paper feed cassette 81 stores a plurality of sheets used for image forming processing, and is provided below the exposure unit 1. The manual feed tray 82 is provided on the side surface of the image forming apparatus 100. The paper feed unit 80 feeds paper one by one from the paper feed cassette 81 or the manual feed tray 82 to the paper transport path 40. The sheet conveyance path 40 is formed between the sheet feeding section 80 and the intermediate transfer belt 61 and the secondary transfer unit 30 and the sheet discharge tray 91 via the fixing unit 70.

  The image reading unit 90 includes document tables 92 and 93 on the upper surface and a CIS unit 50 inside. On the upper surface of the image reading unit 90, an automatic document feeder 120 that transports a document placed on the placement tray 121 is mounted so as to be openable and closable with a rear side end portion as a support shaft. The image reading unit 90 generates an image from a document passing on the document table 93 by the conveyance of the automatic document conveyance device 120 or a document placed on the document table 92 by a manual operation involving opening and closing of the automatic document conveyance device 120 by an operator. Read data.

  As shown in FIGS. 2A and 2B, the CIS unit 50 includes a plurality of light sources 51, a rod lens array 52, a plurality of imaging elements 53, and a plurality of sensor substrates (corresponding to the support member of the present invention). .) 54 and dust-proof glass 55, etc., and read pixel information from the document. The plurality of light sources 51 are, for example, LED arrays in which a plurality of LEDs are arranged, and irradiate a document. The rod lens array 52 condenses the reflected light from the document onto a plurality of image sensors 53. The plurality of imaging elements 53 each read pixel information imaged by the rod lens array 52. The plurality of sensor substrates 54 are arranged in a line along the main scanning direction, and a plurality of image sensors 53 are arranged in a line on the plane side along the main scanning direction.

  As shown in FIG. 3, the image forming apparatus 100 further includes a control unit 20, an interpolation unit 21, a storage unit 22, and a moving mechanism (corresponding to the moving unit of the present invention) 23.

  Since the image sensor 53 does not exist at each joint of the plurality of sensor substrates 54, a missing pixel D (see FIG. 6) corresponding to one pixel occurs at a location corresponding to the joint. The interpolation unit 21 interpolates this missing pixel D.

  The storage unit 22 temporarily stores pixel information read by the plurality of image sensors 53.

  As shown in FIG. 4, the moving mechanism 23 includes a solenoid 231 and a steel bar 232. The solenoid 231 is disposed in the vicinity of the end of the CIS unit 50 in the main scanning direction, and the controller 20 switches on / off of energization. An iron bar 232 is attached to the end of the solenoid 231 on the CIS unit side, and the iron bar 232 is attached to the bottom surface side of the plurality of sensor substrates 54. Hereinafter, although the moving mechanism 23 is described as moving only the plurality of sensor substrates 54 and the plurality of imaging elements 53 in the main scanning direction, the entire CIS unit 50 may be moved in the main scanning direction.

  As shown in FIG. 5A, the plurality of sensor boards 54 are positioned at the first position, which is the home position of the CIS unit 50, in a state where no current flows through the solenoid 231. As shown in FIG. 5B, when a current flows through the solenoid 231, the solenoid 231 pulls the iron bar 232 toward the solenoid 231 and moves the plurality of sensor substrates 54 attached to the iron bar 232 to the second position. The plurality of imaging elements 53 move as the plurality of sensor substrates 54 move. The second position is separated from the first position by a predetermined distance along the main scanning direction.

  As described above, the plurality of sensor boards 54 move a predetermined distance from the first position to the second position along the main scanning direction by switching on / off the energization of the solenoid 231 by the control unit 20. The predetermined distance is an integer multiple of 1 or more of the pitch of the number of missing pixels D. Since the missing pixel D is one pixel, the predetermined distance is an integer multiple of 1 or more of the pitch L1 (see FIG. 6) for one pixel.

  Accordingly, the interpolation unit 21 reads pixel information of the missing pixel D that cannot be read in a state where the plurality of sensor substrates 54 are positioned at the first position, while the plurality of sensor substrates 54 are positioned at the second position. Since it is possible to easily determine which pixel information matches among the pixel information, interpolation of the missing pixel D can be facilitated.

  Specifically, as shown in FIG. 6, each of the plurality of sensor substrates 54 is provided with 16 image sensors 53 and has an effective reading length of 305 mm. That is, the effective reading length of one image sensor 53 is 305/16 = 18.56 mm. Further, since the pitch L1 of one pixel is 42.3 μm, the number of pixels of the image sensor 53 is 18.56 mm / 42.3 μm−1 = about 437. The predetermined distance is 42.3 × (1 to 437) since it is an integer multiple of 1 or more of the pitch L1 of one pixel. For example, when the predetermined distance is one time the pitch L1 of one pixel, the pixel information of the missing pixel D in a state where the plurality of sensor substrates 54 are located at the first position is the plurality of sensor substrates 54 at the second position. This coincides with the top pixel information of the pixel information read in the positioned state.

  In this embodiment, the plurality of sensor boards 54 can be easily moved by the solenoid 231 by setting the predetermined distance to 42.3 × 236 = 9.9828 mm or 42.3 × 237 = 10.251 mm.

  The control unit 20 controls each functional unit. The control unit 20 generates image data based on the pixel information read by the plurality of imaging elements 53 and the pixel information of the missing pixel D interpolated by the interpolation unit 21 during scanning. At the time of copying, an image is formed on paper using image data generated by the same processing as that at the time of scanning.

  As shown in FIG. 7, the control unit 20 receives a scan start instruction with the plurality of sensor substrates 54 positioned at the first position (S11). Upon receiving the scan start instruction, the control unit 20 reads and stores the pixel information from the document by the plurality of image sensors 53 while moving the CIS unit 50 from the start position to the end position in the sub-scanning direction orthogonal to the main scanning direction. It memorize | stores in the part 22 (S12).

  The control unit 20 returns the CIS unit 50 to the start position (S13).

  The control unit 20 causes a current to flow through the solenoid 231 to move the plurality of sensor substrates 54 to the second position (S14). The control unit 20 reads the pixel information from the document with the plurality of imaging elements 53 while moving the CIS unit 50 from the start position to the end position in the sub-scanning direction, and stores the pixel information in the storage unit 22 (S15).

  The control unit 20 returns the CIS unit 50 to the start position (S16), and stops the current flowing through the solenoid 231 to move the plurality of sensor substrates 54 to the first position (S17).

  The control unit 20 refers to the storage unit 22 and causes the interpolation unit 21 to interpolate the missing pixel D (S18). Specifically, the interpolating unit 21 positions pixel information corresponding to the missing pixel D that cannot be read in a state where the plurality of sensor substrates 54 are positioned at the first position, and positions the plurality of sensor substrates 54 at the second position. Extracted from the pixel information read in the state. Then, pixel information corresponding to the extracted missing pixel D is interpolated into the pixel information read with the plurality of sensor substrates 54 positioned at the first position.

  The control unit 20 generates image data based on the pixel information after interpolation (S19).

  Thereby, the control part 20 can interpolate the missing pixel D using accurate pixel information by reading the image again without estimating the missing pixel D. For this reason, an accurate image can be read with any original (image image original having a fine periodic pattern).

  In the above-described embodiment, the moving mechanism 23 is composed of the solenoid 231 and the iron bar 232. However, the moving mechanism 23 applies a rotational force to the pinion and pinion which are a rack having a toothed plate and a small-diameter circular gear. You may comprise from the motor to supply.

  The image forming apparatus 100A according to the second embodiment is different from the image forming apparatus 100 according to the first embodiment in processing at the time of reading an image by the control unit 20A. Only the differences will be described below.

  As shown in FIG. 8, the control unit 20A performs the processes of S11 to S14 in FIG.

  The control unit 20A reads the pixel information from the document by the plurality of imaging elements 53 while moving the CIS unit 50 from the end position to the start position in the sub-scanning direction, and stores the pixel information in the storage unit 22 (S21). 20 A of control parts perform the process of S17-S19 in FIG.

  As described above, when reading the image for the second time, the control unit 20A reads the pixel information by the plurality of imaging elements 53 while moving the CIS unit 50 from the end position to the start position without returning the CIS unit 50 to the start position. Reading time can be shortened.

  In the above-described embodiment, the image forming apparatus has been described as an example. However, an image reading apparatus including the image reading unit 90 may be used.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 100,100A ... Image forming apparatus 20, 20A ... Control part 21 ... Interpolation part 22 ... Storage part 23 ... Solenoid 231 ... Iron bar 50 ... CIS unit 53 ... Image sensor 54 ... Sensor substrate 90 ... Image reading part

Claims (5)

A plurality of image pickup devices arranged in a line in the main scanning direction, and an image from a document when the plurality of image pickup devices move between a start position and an end position in a sub-scanning direction orthogonal to the main scanning direction. An image reading unit to be read;
A moving unit that moves at least the plurality of imaging elements to a first position or a second position separated by a predetermined distance in the main scanning direction;
A control unit that causes the image reading unit to move the plurality of imaging elements from the start position to the end position at each of the first position and the second position;
An image reading apparatus comprising: an interpolation unit that interpolates missing pixels based on an image read by the image reading unit at each of the first position and the second position.   The image reading apparatus according to claim 1, wherein the predetermined distance is a distance equal to an integer multiple of 1 or more of a pitch for one pixel.   The control unit causes the image reading unit to move the plurality of imaging elements from the start position to the end position in a state where the plurality of imaging elements are positioned at the first position, and causes the moving unit to move the plurality of imaging elements to the plurality of imaging elements. 3. The image reading apparatus according to claim 1, wherein the plurality of image pickup elements are moved from the end position to the start position by the image reading unit after the image pickup element is moved to the second position.   The said moving part is comprised from the supporting member which supports these image pick-up elements, and the solenoid which moves the said supporting member to the said 1st position and the said 2nd position by turning on / off electricity. 4. The image reading apparatus according to any one of 3 above. An image reading apparatus according to any one of claims 1 to 4,
An image forming apparatus comprising: an image forming unit that performs an image forming process on a sheet based on an image read by the image reading apparatus.

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