JP4737044B2 - Image reading apparatus, image forming apparatus, and image correction program - Google Patents

Description

  The present invention relates to an image reading apparatus, an image forming apparatus, and an image correction program.

  In Patent Document 1, the same image data is corrected using main data obtained by correcting image data using main shading data obtained for each document and sub-shading data obtained in advance before a job and from which noise components are removed. An image reading apparatus that compares sub-data and interpolates main data with corresponding sub-data for a portion where the difference between both is large is disclosed. Japanese Patent Laid-Open No. 2004-260688 discloses a case where a white reference roller provided at a position facing a document reading surface and spaced apart by a predetermined distance is rotated to guide a conveyed document and read image information. An image reading apparatus that switches between the guide surface of the white guide roller and the white reference surface when the image is corrected by reading the image is disclosed. Further, Patent Document 3 discriminates dirt at a document reading position, calculates an average value of read values of a predetermined area read by a reading unit that reads an image, and calculates the calculated average value and an average value of other predetermined areas. An image reading apparatus that binarizes image data using a value obtained by further averaging the above is disclosed.

JP 2006-13833 A JP 2001-313794 A JP 2004-266725 A

  However, in the conventional example, when the reflected light is imaged by a plurality of lenses arranged in the main scanning direction, the amount of light input to the photoelectric conversion element periodically changes in the main scanning direction. There was a problem that it could not be generated with high accuracy.

  The present invention provides an image reading apparatus, an image forming apparatus, and an image correction program capable of generating shading data with high accuracy even when reflected light is imaged by a plurality of lenses arranged in the main scanning direction. With the goal.

In order to achieve the above object, the present invention according to claim 1 includes a light source unit, a light amount detection member that detects a light amount of reflected light or transmitted light of light emitted by the light source unit as a pixel row in one direction, A plurality of lenses having the same diameter , which are arranged in the one direction and image the reflected light or transmitted light of the light emitted by the light source unit on the light amount detection member, and the white reference reflected light of the light emitted by the light source unit. When each of the lenses forms an image on the light amount detection member, a determination unit that determines for each pixel whether or not the light amount detected by the light amount detection member is effective, and the determination unit determines that the light amount is not effective the amount of pixels, by the light amount detecting member at a same interval as arrangement interval of the lens is replaced with the amount of light pixels detected, and a shading data generating means for generating shading data An image reading device.

  According to a second aspect of the present invention, the light source unit equalizes at least three light emitting diodes that respectively emit light of three colors corresponding to the three primary colors of color light, and light emitted by the light emitting diodes in the one direction. The image reading apparatus according to claim 1, further comprising a light guide member.

  The present invention according to claim 3 is the image reading apparatus according to claim 1 or 2, wherein the lens is an erecting equal-magnification imaging lens.

  According to a fourth aspect of the present invention, there is provided the image reading apparatus according to any one of the first to third aspects, wherein the determination unit determines a light amount that is equal to or greater than a predetermined threshold value as an effective light amount.

The present invention according to claim 5 is arranged in the one direction, a light source unit, a light amount detection member that detects a light amount of reflected light or transmitted light of the light irradiated by the light source unit as a pixel row in one direction, A plurality of lenses having the same diameter for imaging reflected light or transmitted light of light emitted from the light source unit on the light amount detection member, and white reference reflected light of light emitted from the light source unit are detected by the lenses. A determination unit that determines, for each pixel, whether or not the light amount detected by the light amount detection member is effective when the image is formed on the member, and a light amount of a pixel that is determined to be ineffective by the determination unit, by substituting amount of pixels where the light quantity detecting member detects at a same interval as arrangement interval of the lens, the shading data generating means for generating shading data, the shading data generation hands There is an image forming apparatus and an image forming unit for forming an image based on the generated shading data.

  According to a sixth aspect of the present invention, the light source unit equalizes at least three light emitting diodes that respectively emit three colors of light corresponding to the three primary colors of color light, and the light emitted by the light emitting diodes in the one direction. The image forming apparatus according to claim 5, further comprising a light guide member.

  The present invention according to claim 7 is the image forming apparatus according to claim 5 or 6, wherein the lens is an erecting equal-magnification imaging lens.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the fifth to seventh aspects, the determination unit determines that the light amount equal to or greater than a predetermined threshold is an effective light amount.

According to a ninth aspect of the present invention, there is provided a plurality of light beams having the same diameter arranged in the one direction with respect to a light amount detection member that detects the amount of white reference reflected light of the light emitted from the light source unit as a pixel row in one direction. When each lens forms an image, the step of determining for each pixel whether or not the light amount detected by the light amount detection member is effective, and the light amount of the pixel determined that the light amount is not effective are the same as the lens arrangement interval The image correction program causes the computer to execute a step of generating shading data by replacing the light amount of the pixel detected by the light amount detection member at an interval .

  According to the present invention, shading data can be generated with high accuracy even when reflected light is imaged by a plurality of lenses arranged in the main scanning direction.

Next, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, an outline of the image forming apparatus 10 is shown. The image forming apparatus 10 is for color, for example, and includes an image forming unit 12 and a document reading device 14. The image forming unit 12 is of a xerographic type, for example, and has a paper feed tray 16 on which sheets such as paper are stacked, and forms an image on a sheet supplied from the paper feed tray 16 to the sheet conveyance path 20. It is like that.

  That is, the image forming unit 12 includes an image carrier 22 made of a photosensitive member, a charger 24 that uniformly charges the image carrier 22, and an image carrier 22 that is uniformly charged by the charger 24. An exposure device 26 that forms a latent image, a developing device 28 that visualizes the latent image on the image carrier 22 formed by the exposure device 26 with toner, and an intermediate transfer belt that transfers the toner image formed by the developing device 28 The image forming apparatus includes a primary transfer device 32 that transfers to 30 and an image carrier cleaner 34 that cleans toner remaining on the image carrier 22. The exposure device 26 is of, for example, a laser scanning type, and outputs an image of a document read by a first photoelectric conversion element 62 and a second photoelectric conversion element 156 (to be described later) of the document reading device 14 as a laser on / off signal. To do. The developing device 28 is, for example, a rotary type, and has four color developing devices 36a, 36b, 36c, and 36d of Y (yellow), M (magenta), C (cyan), and K (black) arranged around it. It rotates so as to face the image carrier 22 when developing each color. The primary transfer device 32 is composed of, for example, a corotron, and the transfer device 32 transfers four color toner images to the intermediate transfer belt 30. The toner image transferred to the intermediate transfer belt 30 is transferred to a sheet by the secondary transfer device 38, this sheet is sent to the fixing device 40, and the toner image is fixed to the sheet by the fixing device 40. The fixed sheet is discharged to the discharge tray 42. The toner remaining on the intermediate transfer belt 30 is scraped off by the intermediate transfer belt cleaner 44.

  A resist roll 46 is disposed in the sheet conveyance path 20. The registration roll 46 is controlled so as to temporarily stop the supplied sheet and supply the sheet to the secondary transfer device 38 in synchronization with the timing at which the toner image is formed on the intermediate transfer belt 30.

  The image forming unit 12 forms a monochrome (achromatic) or color (chromatic) image of a predetermined gradation on a sheet according to settings input via a user interface (UI) device 120 described later. Have been to.

  The document reader 14 includes, for example, an automatic document feeder 48 and a reduction / reduction optical system 50 that reads an image formed on the surface (first surface) of the document. Further, in the automatic document feeder 48, a contact image sensor (CIS) 52 for reading an image formed on the back surface (second surface) of the document is provided. In other words, the document reading device 14 has a function of flowing and reading the surface of the document sent by the automatic document feeder 48, a function of reading the surface of the document placed on the platen glass 54, and the automatic document feeder 48. And a function of reading both sides (first side and second side) of the fed document.

FIG. 2 is a side view showing an outline of the document reading device 14.
The reduction optical system 50 includes a full rate carriage 56, a half rate carriage 58, a lens 60, a photoelectric conversion element 62, and a processing control unit 64. The full-rate carriage 56 includes a first light source 66 and a first mirror 68, and the document scanning device 14 has the scanning direction (sub-scanning direction) in the sub-scanning direction (left side to right side in FIG. 2). The entire stroke is moved in the scanning direction.

  The first light source 66 is a lamp such as halogen or xenon that extends in the main scanning direction of the document. For example, the energy of the wavelength of about 545 nm is the maximum, and the energy of the wavelengths of about 485 nm, about 585 nm, and about 620 nm is the other. It has the characteristic (spectral distribution) which becomes larger than the energy of the wavelength. The half-rate carriage 58 includes a second mirror 70 and a third mirror 72 and is configured to move a half stroke in the sub-scanning direction within the document reading device 14.

  The lens 60 is used for a document placed on the platen glass 54 provided above the moving range of the full rate carriage 56 and the half rate carriage 58 or a document passing through the transported document reading position 74 via the CVT glass 76. The reflected light of the light emitted from the first light source 66 is received through the first mirror 68, the second mirror 70, and the third mirror 72 to form an image.

  The photoelectric conversion element 62 receives the reflected light at the imaging position of the reflected light by the lens 60 and, for example, R (red) and G (green) for each pixel by a photodiode provided with RGB filters (primary color filters). , B (blue purple), for example, a 3-line color CCD that outputs an analog electrical signal corresponding to each light quantity to the processing control unit 64.

  The processing control unit 64 processes the electrical signal input from the photoelectric conversion element 62 as image data, and controls each unit constituting the document reading device 14. Note that the processing control unit 64 may be arranged in the image forming unit 12 together with a control unit (not shown) that controls each unit constituting the image forming unit 12.

  Further, a reference white plate (not shown) that reflects the light emitted by the first light source 66 is provided in the vicinity of the transported document reading position 74, and the first light source 66 is located with respect to the reference white plate. The photoelectric conversion element 62 can receive the reflected light of the irradiated light via the first mirror 68, the second mirror 70, the third mirror 72 and the lens 60.

  When the original reading device 14 reads an image on the surface of the original placed on the platen glass 54, the full-rate carriage 56 and the half-rate carriage 58 respectively emit light from the first light source 66 toward the original. By moving in the scanning direction, the photoelectric conversion element 62 sequentially receives reflected light corresponding to the entire surface of the document.

  The automatic document feeder 48 includes a document table 80 on which a large number of documents are placed, a document conveyance path 82 that conveys the document, and a discharge table 84 from which the document after the image is read is discharged. The document conveyance path 82 is formed in a U-shape, and includes a nudger roll 86, a feed roll 88, a pre-registration roll 90, a registration roll 92, a platen roll 94, an out roll 96, and a discharge roll 98 that constitute a conveyance device. It has been. The nudger roll 86 descends when the document is fed, and picks up the document placed on the document table 80. The feed roll 88 feeds the original sent from the nudger roll 86 and supplies only the uppermost original. The pre-registration roll 90 temporarily stops the document sent from the feed roll 88 and corrects skew feeding. The registration roll 92 temporarily stops the document sent from the pre-registration roll 90 and takes a reading timing. The platen roll 94 causes the document passing through the document transport path 82 to face the CVT glass 76. When the document is discharged, it is discharged to the discharge table 84 through the out roll 96 and the discharge roll 98.

  Further, a first sensor 100 is disposed upstream of the registration roll 92 in the document conveyance direction, and a second sensor 102 is disposed downstream of the registration roll 92 in the document conveyance direction. The first sensor 100 detects the timing at which the document approaches the registration roll 92 and outputs the detection result to the automatic document feeder controller 110 described later. The second sensor 102 detects the timing at which the document is conveyed from the registration roll 92 toward the platen roll 94 and outputs the detection result to the automatic document feeder control unit 110.

  The contact image sensor 52 described above is disposed between the out roll 96 and the discharge roll 98 so as to read the back side of the document from above. Below the contact image sensor 52, the reference white plate 104 is disposed so as to face the contact image sensor 52 with the document conveyance path 82 interposed therebetween. The reference white plate 104 has a reflecting surface facing upward that is white that serves as a reference for image reading, and the reference reflected light with respect to white that is emitted from a second light source unit 152 (to be described later) of the contact image sensor 52. Is reflected toward the contact image sensor 52. Further, the reference white plate 104 can be moved in the sub-scanning direction with respect to the document by a solenoid or a motor (not shown).

FIG. 3 is a block diagram showing an outline of the configuration of the document reading device 14.
As shown in FIG. 3, the document reading device 14 includes a controller 106, a first image reading control unit 108, an automatic document feeder control unit 110, a roll control unit 112, a scanning control unit 114, an illumination control unit 116, and a second. The image reading control unit 118 is included in the processing control unit 64, for example.

  The controller 106 controls each part of the document reading device 14 via the first image reading control unit 108 according to a setting input via a user interface (UI) device 120 such as a touch panel. The first image reading control unit 108 operates according to the control of the controller 106, acquires an image signal corresponding to the image on the surface of the document by controlling the reduction optical system 50, and an automatic document feeder control unit. 110 and the second image reading control unit 118 perform communication for reading a document image. Here, the first image reading control unit 108 includes a CPU (not shown), operates by reading a program stored in the ROM 122, and performs setting such as setting for the first light source 66 of the reduction optical system 50 to NVM (Non Volatile Memory: (Nonvolatile memory) 124. The first image reading control unit 108 controls the scanning control unit 114 that controls the motor 126 that rotates to move the full rate carriage 56 and the half rate carriage 58, and the first light source 66 of the reduction optical system 50. The illumination control unit 116 to be controlled is controlled.

  The automatic document feeder control unit 110 includes a CPU (not shown) and communicates with the first image reading control unit 108 to feed a feed roll 88, a pre-registration roll 90, a registration roll 92, a platen roll 94, and an out-roll. 96 and a roll control unit 112 that controls motors (not shown) for driving the discharge rolls 98, and the detection results of the first sensor 100 and the second sensor 102 are received, and the area on the surface of the document ( A document front surface area signal indicating a reading period) and a document back surface area signal indicating a back surface area (reading period) of the document are output to the first image reading control unit 108.

  The second image reading control unit 118 includes a RAM 128 and a CPU 130, communicates with the first image reading control unit 108, generates an LS (line synchronization signal) synchronized with a clock (not shown), and By controlling the contact image sensor 52 in accordance with the document back surface area signal received via the image reading control unit 108, an image signal corresponding to the image on the back surface of the document is acquired. The RAM 128 stores image data read from the reflected light from the reference white plate 104 by the contact image sensor 52. Further, the RAM 128 stores image data read from reflected light (black output) from the reference white plate 104 as an offset in a state where a second light source unit 152 to be described later is not lit, for each pixel. Also good.

  The CPU 130 uses the image data read from the reflected light from the reference white plate 104 stored in the RAM 128 to generate shading data by selection described later, determine the effectiveness of the output level (light level) for each pixel, and perform shading by replacement. Data generation and image correction processing are performed (see FIG. 10). The CPU 130 operates by reading a program stored in the ROM 132, controls the contact image sensor 52 in accordance with a predetermined initial value stored in a non-volatile memory (NVM) 134, and generates generated shading data. Etc. are stored in the RAM 128.

Next, the contact image sensor 52 will be described in detail.
4 to 6, the configuration of the contact image sensor 52 is shown.
The contact image sensor 52 includes, for example, an oscillator 136, a sensor control unit 138, a lighting time rate (duty) adjustment unit 140, LED drive units 142-1 to 142-3, and red light emitting diodes (R-LEDs) 144-1 to 144. -4, green light emitting diodes (G-LED) 146-1 to 146-4, blue light emitting diodes (B-LED) 148-1 to 148-4, light guide tubes 150-1 and 150-2, rod lens array 154 And a photoelectric conversion element 156.

  The oscillator 136 generates a clock (CLK) having a predetermined frequency and outputs it to the sensor control unit 138. The sensor control unit 138 receives the clock input from the oscillator 136 and the line synchronization signal (LS) input from the second image reading control unit 118, and responds to the control of the second image reading control unit 118. The lighting time rate adjusting unit 140 and the photoelectric conversion element 156 are controlled. Here, the sensor control unit 138 outputs a clock and a line synchronization signal to the lighting time rate adjustment unit 140. In addition, the sensor control unit 138 includes a function of A / D converting an analog color image signal (RGB) input from the photoelectric conversion element 156, and has a predetermined function according to the control of the second image reading control unit 118. A color image signal having a gradation value or a monochrome image signal having a predetermined gradation value is output to the second image reading control unit 118.

  The lighting time rate adjustment unit 140 receives the clock and line synchronization signal from the sensor control unit 138, and lights the red light emitting diodes 144-1 to 144-4 only for a predetermined number of clocks according to the control of the sensor control unit 138. An R color lighting control signal for turning on the green light emitting diodes 146-1 to 146-4 is output to the LED drive unit 142-1, and the green light emitting diodes 146-1 to 146-4 are turned on only during a predetermined number of clocks. Output to the drive unit 142-2, and output a B color lighting control signal to the LED drive unit 142-3 for lighting the blue light emitting diodes 148-1 to 148-4 only for a predetermined number of clocks. .

  The LED driving unit 142-1 (FIG. 4) supplies a predetermined driving current to the red light emitting diodes 144-1 to 144-4 according to the R color lighting control signal input from the lighting time rate adjusting unit 140, and The light emitting diodes 144-1 to 144-4 are turned on for a predetermined time. The LED driving unit 142-2 supplies a predetermined driving current to the green light emitting diodes 144-1 to 144-4 according to the G color lighting control signal input from the lighting time rate adjusting unit 140, and the green light emitting diode 144- 1 to 144-4 are lit for a predetermined time. The LED driving unit 142-3 supplies a predetermined driving current to the blue light emitting diodes 144-1 to 144-4 according to the B color lighting control signal input from the lighting time rate adjusting unit 140, and the blue light emitting diode 144- 1 to 144-4 are lit for a predetermined time.

The red light emitting diodes 144-1 to 144-4 are light emitting diodes that emit light corresponding to red in the three primary colors. The green light emitting diodes 146-1 to 146-4 are light emitting diodes that emit light corresponding to green in the three primary colors. The blue light emitting diodes 148-1 to 148-4 are light emitting diodes that emit light corresponding to blue-violet in the three primary colors.
As shown in FIG. 5, the red light emitting diodes 144-1 and 144-2 are disposed at both ends of the light guide tube 150-1, and the green light emitting diodes 146-1 and 146-2 are disposed at both ends of the light guide tube 150-1. The blue light emitting diodes 148-1 and 148-2 are respectively disposed at both ends of the light guide tube 150-1. The red light emitting diodes 144-3 and 144-4 are respectively disposed at both ends of the light guide tube 150-2, and the green light emitting diodes 146-3 and 146-4 are respectively disposed at both ends of the light guide tube 150-2. The blue light emitting diodes 148-3 and 148-4 are disposed at both ends of the light guide tube 150-2.

The light guide tubes 150-1 and 150-2 are arranged in parallel to the rod lens array 154, respectively, and the red light emitting diodes 144-1 to 144-4, the green light emitting diodes 146-1 to 146-4, and the blue color The lights emitted from the light emitting diodes 148-1 to 148-4 are made uniform, and the uniformed light is irradiated toward the document conveyance path 82 side.
That is, the red light emitting diodes 144-1 to 144-4, the green light emitting diodes 146-1 to 146-4, the blue light emitting diodes 148-1 to 148-4, and the light guide tubes 150-1 and 150-2 are the second ones. A light source unit 152 is configured.

  The rod lens array 154 is an erecting equal-magnification imaging lens (rod lens) array having a short optical path length in which fiber strands having substantially the same diameter, such as a SELFOC (registered trademark) lens array, are arranged in the main scanning direction with respect to a document. The reflected light of the light emitted by the second light source unit 152 is imaged. For example, the rod lens array 154 may include rod lenses arranged in a line in the main scanning direction, or rod lenses arranged in a staggered manner in the main scanning direction, and adjacent rod lenses. The reflected light corresponding to the document image may be transmitted by superimposing a part of the reflected light transmitted by the. The rod lens array 154 transmits reflected light corresponding to, for example, 14 pixels by a single rod lens.

  The photoelectric conversion element 156 receives the reflected light imaged by the rod lens array 154 through the cover glass 160 provided under the image sensor main body 158 shown in FIG. ) Are output to the sensor control unit 138 by analog electric signals (image signals) corresponding to respective light amounts of R (red), G (green), and B (blue-violet) in pixel units. For example, a linear CCD (color). That is, the photoelectric conversion element 156 detects the amount of reflected light from the document as a pixel row in the main scanning direction.

Next, shading data generation processing and image correction processing performed by the CPU 130 will be described in detail.
FIG. 7 is a graph showing data stored in the RAM 128 for the CPU 130 to correct an image read by the contact image sensor 52, and FIG. 7A is a graph showing an example of shading data in the main scanning direction generated by the CPU 130. (B) is a graph showing an example of image data in the main scanning direction before shading correction read by the contact image sensor 52, and (C) shows an example of image data in the main scanning direction after shading correction by the CPU. It is a graph.
When the reference white plate 104 is free from dirt and foreign matter, as shown in FIG. 7A, the amount of reflected light from the reference white plate 104 decreases on both sides in the main scanning direction and the arrangement of rod lenses. It changes at substantially the same period as the interval. Therefore, as shown in FIG. 7B, the image data read by the contact image sensor 52 has uneven brightness in the main scanning direction. Therefore, the CPU 130 performs shading correction to generate the image data shown in FIG. 7C by dividing the image read by the contact image sensor 52 by the shading data.

8A and 8B are diagrams showing the positions of foreign matters attached on the reference white plate 104, wherein FIG. 8A is a top view showing a state where round foreign matters are attached, and FIG. It is a top view which shows the state which the long foreign material adhered to the subscanning direction.
As described above, the reference white plate 104 is moved in the sub-scanning direction. The second image reading control unit 118 (FIG. 3) acquires shading data in the main scanning direction on the A line on the reference white plate 104, moves the reference white plate 104, and then moves in the main scanning direction. Shading data is acquired on the B line on the reference white plate 104. Here, the second image reading control unit 118 compares the shading data acquired on the A line and the B line, and selects the value of the white one (the one with the higher lightness) for each pixel. One shading data is generated (shading data generation by selection).

Therefore, as shown in FIG. 8A, even if a round foreign matter is attached on the A line, the second image reading control unit 118 does not have the foreign matter on the B line. By acquiring, it is possible to prevent erroneous shading data from being generated by a round foreign object.
On the other hand, as shown in FIG. 8B, the second image reading control unit 118 operates on the A line and the B line with respect to the foreign matter extending over the same position in the main scanning direction on the A line and the B line. Generation of shading data by the above selection cannot prevent generation of erroneous shading data.
Therefore, the CPU 130 further determines for each pixel whether or not the output level detected by the photoelectric conversion element 156 is valid in generating shading data by selection on the A line and the B line. .

FIG. 9 is a graph showing a state in which an invalid output level is included in the shading data by selection. FIG. 9A is a graph showing an example of shading data for all pixels in the main scanning direction, and FIG. It is a correspondence diagram showing the relationship between the graph in which the broken line part shown in (A) is enlarged and the arrangement of rod lenses of the rod lens array 154.
As described above, the amount of reflected light from the reference white plate 104 changes at substantially the same period as the arrangement interval of the rod lenses 154a in the main scanning direction.

The CPU 130 is configured to determine, for each pixel, an effective light amount and a light amount equal to or greater than a predetermined threshold S with respect to the light amount reflected by the reference white plate 104.
The CPU 130 recognizes a range in which pixels determined by the CPU 130 that the amount of reflected light from the reference white plate 104 is not an effective amount as a range in which foreign matter is attached (foreign matter range). Then, the CPU 130 replaces the light amount of each pixel included in the foreign substance range with the light amount of the pixel detected by the photoelectric conversion element 156 at an interval of, for example, 14 pixels corresponding to the number of pixels transmitted by one rod lens 154a. Thus, shading data is generated (generation of shading data by replacement). In other words, the CPU 130 sets the foreign substance range as a light-amount replacement range, and includes a range including pixels before 14 pixels in the main scanning direction of each pixel in the replacement range, or 14 in the main scanning direction of each pixel in the replacement range. The range including the pixel after the pixel is used as the replacement range, and the light amount of the pixel detected in the replacement range is corrected to be the light amount of the corresponding pixel in the replacement range.

FIG. 10 is a flowchart showing a process (S10) performed by the document reading apparatus 14 to generate shading data for the contact image sensor 52.
As shown in FIG. 10, in step 100 (S100), the second image reading control unit 118 passes red sensor 144-1 to 144-4 through the sensor control unit 138 and the lighting time rate adjustment unit 140. The green light emitting diodes 146-1 to 146-4 and the blue light emitting diodes 148-1 to 148-4 are turned on, and the superimposed light is irradiated toward the reference white plate 104.

  In step 102 (S102), the photoelectric conversion element 156 detects the amount of reflected light in the main scanning direction by the line A of the reference white plate 104 for each pixel.

  In step 104 (S104), the photoelectric conversion element 156 detects the amount of reflected light in the main scanning direction by the line B of the reference white plate 104 for each pixel.

  In step 106 (S106), the second image reading control unit 118 generates shading data by selection.

  In step 108 (S108), the second image reading control unit 118 determines the validity of the output level for each pixel with respect to the shading data generated in the process of S106.

  In step 110 (S110), the second image reading control unit 118 generates shading data by replacement according to the determination result in the processing of S108.

1 is a side view illustrating an outline of an image forming apparatus according to an embodiment of the present invention. 1 is a side view showing an outline of a document reading apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating an outline of a configuration of a document reading apparatus. It is a block diagram which shows the outline | summary of a structure of a contact | adherence image sensor. It is the top view which looked at the light guide tube and the rod lens array from the lower part. It is sectional drawing which looked at the contact type image sensor from the side. FIG. 7A is a graph showing data stored in a RAM for correcting the image read by the contact image sensor, and FIG. 5A is a graph showing an example of shading data in the main scanning direction generated by the CPU; () Is a graph showing an example of image data in the main scanning direction before shading correction read by the contact image sensor, and (C) is a graph showing an example of image data in the main scanning direction after shading correction by the CPU. It is a figure which shows the position of the foreign material adhering on a reference | standard white board, Comprising: (A) is a top view which shows the state in which the round foreign material adhered, (B) is long in a subscanning direction with a round foreign material. It is a top view which shows the state to which the foreign material adhered. It is a graph which shows the state where the light quantity which is not effective is contained in the shading data by selection, Comprising: (A) is a graph which shows the shading data example with respect to all the pixels of a main scanning direction, (B) is shown to (A). It is a corresponding figure which shows the relationship between the graph which expanded the broken-line part, and the arrangement | sequence of the rod lens of a rod lens array. 6 is a flowchart illustrating processing (S10) performed by the document reading device 14 to generate shading data for the contact image sensor 52.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming part 14 Document reading apparatus 22 Image holding body 28 Developing apparatus 36a, 36b, 36c, 36d Developer 48 Automatic document feeder 50 Reduction optical system 52 Contact type image sensor 54 Platen glass 56 Full-rate carriage 58 Half Rate carriage 60 Lens 62 Photoelectric conversion element 64 Processing control unit 66 First light source 104 Reference white plate 106 Controller 108 First image reading control unit 110 Automatic document feeder control unit 118 Second image reading control unit 120 UI device 128 RAM
130 CPU
134 NVM
136 Oscillator 138 Sensor control unit 140 Lighting time rate adjustment unit 142-1 to 142-3 LED driving unit 144-1 to 144-4 Red light emitting diodes 146-1 to 146-4 Green light emitting diodes 148-1 to 148-4 Blue Light-emitting diodes 150-1 and 150-2 Light guide tube 152 Second light source unit 154 Rod lens array 154a Rod lens 156 Photoelectric conversion element

Claims (9)

A light source unit, a light amount detection member that detects the amount of reflected light or transmitted light emitted from the light source unit as a pixel row in one direction, and a reflection of light that is arranged in the one direction and is emitted from the light source unit A plurality of lenses having the same diameter for imaging light or transmitted light on the light quantity detection member, and white reference reflected light of light emitted by the light source unit, when each of the lenses forms an image on the light quantity detection member, A determination unit that determines whether or not the light amount detected by the light amount detection member is effective for each pixel, and the light amount of the pixel determined by the determination unit that the light amount is not effective is the same as the array interval of the lenses. An image reading apparatus comprising: a shading data generation unit configured to generate shading data by opening and replacing the light amount of the pixel detected by the light amount detection member.   The light source unit includes at least three light emitting diodes that respectively emit light of three colors corresponding to the three primary colors of color light, and a light guide member that equalizes light emitted from the light emitting diodes in the one direction. The image reading apparatus described.   The image reading apparatus according to claim 1, wherein the lens is an erecting equal-magnification imaging lens.   The image reading apparatus according to claim 1, wherein the determination unit determines that a light amount equal to or greater than a predetermined threshold is an effective light amount. A light source unit, a light amount detection member that detects the amount of reflected light or transmitted light emitted from the light source unit as a pixel row in one direction, and a reflection of light that is arranged in the one direction and is emitted from the light source unit A plurality of lenses having the same diameter for imaging light or transmitted light on the light quantity detection member, and white reference reflected light of light emitted by the light source unit, when each of the lenses forms an image on the light quantity detection member, A determination unit that determines whether or not the light amount detected by the light amount detection member is effective for each pixel, and the light amount of the pixel determined by the determination unit that the light amount is not effective is the same as the array interval of the lenses. A shading data generating unit that generates shading data by replacing the light amount of the pixel detected by the light amount detecting member and the shading data generated by the shading data generating unit Image forming apparatus and an image forming unit for forming an image based on the data.   The light source unit includes at least three light emitting diodes that respectively emit three colors of light corresponding to the three primary colors of color light, and a light guide member that equalizes the light emitted by the light emitting diodes in the one direction. The image forming apparatus described.   The image forming apparatus according to claim 5, wherein the lens is an erecting equal-magnification imaging lens.   The image forming apparatus according to claim 5, wherein the determination unit determines that a light amount equal to or greater than a predetermined threshold is an effective light amount. When each of a plurality of lenses having the same diameter arranged in one direction forms an image with respect to a light amount detection member that detects the amount of white reference reflected light of the light emitted from the light source unit as a pixel row in one direction, The light amount detection member detects whether the light amount detected by the light amount detection member is valid for each pixel, and the light amount detection member detects the light amount of the pixel determined that the light amount is not valid at the same interval as the lens array interval. An image correction program for causing a computer to execute a step of generating shading data by substituting the light amount of the selected pixel.

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