JP2008172327A - Image reader, its control method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader which can correct the light irradiated from a light source to reduce unevenness in chromaticness. <P>SOLUTION: Lighting current value for each LED element of each lamp unit 203, 210 where an LED element of chrominance rank A and an LED element of chrominance rank B are arranged alternately is controlled by a lighting control section 305. The lighting control section 305 generates the lighting signal for each LED element of each lamp unit 203, 210 based on the control signal from a CPU 900 for each chrominance rank and outputs the lighting signal through output terminals P and Q. By this lighting signal, the LED element of chrominance rank A and the LED element of chrominance rank B in each lamp unit 203, 210 are lighted with respective lighting current values. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus, a control method thereof, and an image forming apparatus.

  The image reading apparatus is provided with an illumination device for illuminating a document to be read. In this illumination device, a light source such as a halogen lamp or a xenon lamp is generally used.

In recent years, as a light source having higher efficiency than a halogen lamp, a xenon lamp, or the like, an LED array in which a plurality of LED elements (light emitting diodes) are linearly arranged is known (for example, Patent Document 1).
US Pat. No. 5,767,796

  However, when an LED array in which a plurality of LED elements that emit white light are linearly arranged is used as an illumination device for a color scanner, the arranged LED elements are structurally colored (chromaticity). ) May be different. As a result, in such an LED array, uneven color (variation) occurs.

  For example, as seen in the general spectral characteristics of the LED element shown in FIG. 10, a white LED element is generally coated with a yellow (or red and green) phosphor on a blue light emitting element. It consists of a structure that produces white. Therefore, the color changes greatly depending on the balance between the luminous intensity of the light emitting element itself and the coating amount of the phosphor. Therefore, an LED array using such white LED elements is not optimal as an illumination device for a color scanner.

  Therefore, by selecting and using only white LED elements having the same color, or using only LED elements selected to have the same chromaticity rank, an LED array with less color unevenness can be realized.

  However, since only a part of the manufactured LED elements can be used, the product cost of the LED array increases.

  Even when a light source with uneven color is used, it is possible to output image data from which the influence of uneven color is eliminated by correcting the image data after reading. In this case, the reference color (mainly white) used for correction has an accurate chromaticity, but the intermediate color may have a different color (chromaticity) from the actual original color.

  An object of the present invention is to provide an image reading apparatus, a control method therefor, and an image forming apparatus capable of correcting so as to reduce the color unevenness of light emitted from a light source.

  In order to achieve the above object, the present invention provides at least one linear light source in which a plurality of light emitting elements are arranged in a line, and reflected light from a document irradiated with light from the linear light source as image data. And a correction unit that corrects uneven coloring of the linear light source by controlling lighting current values of the plurality of light emitting elements, and the plurality of light emitting elements of the linear light source include Includes light emitting elements having different chromaticity ranks, and the plurality of light emitting elements are arranged adjacent to light emitting elements having different chromaticity ranks, and the correction means is a lighting current for the plurality of light emitting elements. Provided is an image reading apparatus characterized in that a value is variable for each color rank.

  In order to achieve the above object, according to the present invention, at least one linear light source in which a plurality of light emitting elements are arranged in a line and reflected light from a document irradiated with light from the linear light source are used as image data. A plurality of light emitting elements having different chromaticity ranks, and the plurality of light emitting elements are adjacent to light emitting elements having different chromaticity ranks. A method for controlling an image reading apparatus arranged as described above, characterized in that the color unevenness of the linear light source is corrected by varying a lighting current value for the plurality of light emitting elements for each color rank. Provided is a method for controlling an image reading apparatus.

  In order to achieve the above object, the present invention provides an image forming apparatus including the above image reading apparatus.

  According to the present invention, it is possible to perform correction so as to reduce the color unevenness of the light emitted from the light source.

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

  FIG. 1 is a longitudinal sectional view schematically showing a configuration of an image reading apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the image reading apparatus includes a document conveying device (hereinafter referred to as ADF) 100 and a reader unit 200. The ADF 100 is an optional device that is attached to the reader unit 200 as necessary. In the ADF 100, the uppermost document in the document bundle S set on the document tray 20 with the surface facing up is sent out to the separation unit 2 by the pickup roller 1. The separation unit 2 has a structure in which a separation roller is disposed on the upper side and a separation pad is disposed on the lower side to separate and convey documents one by one.

  When the image on the surface of the document is read, skew correction during separation and conveyance is performed on the separated document by the first registration roller 3. After the skew correction, the original is conveyed from the first registration roller 3 to the paper discharge roller 8 through the second registration roller 4, the first conveyance roller 5, the reading roller 7, and the second conveyance roller 6. During this conveyance, when the document passes the reading position R (the position of the reading roller 7), the image on the surface of the document is read. Then, the document is discharged onto the discharge tray 21 by the discharge roller 8 with the surface of the document facing the discharge tray 21 side.

  When reading images on both the front and back sides of the document, the first registration roller 3 performs skew correction during separation and conveyance on the separated document. After the skew correction, the original is conveyed from the first registration roller 3 to the paper discharge roller 8 through the second registration roller 4, the first conveyance roller 5, the reading roller 7, and the second conveyance roller 6. During the conveyance, when the document passes the reading position R, the image on the surface of the document is read. Then, the document is once transported onto the paper discharge tray 21 by the paper discharge roller 8 until the rear end portion of the document reaches the paper discharge roller 8. When the trailing edge of the original reaches the paper discharge roller 8, the paper discharge roller 8 temporarily stops and then reversely rotates so that the original is switched back. As a result, the document is conveyed toward the second registration roller 4, and the skew correction is performed again on the document by the second registration roller 4.

  After the skew correction, the document is transported from the second registration roller 4 to the paper discharge roller 8 through the first transport roller 5, the reading roller 7 (reading position R), and the second transport roller 6. During the conveyance, when the document passes the reading position R, the image on the back side of the document is read. Then, the document is once transported onto the paper discharge tray 21 by the paper discharge roller 8 until the rear end portion of the document reaches the paper discharge roller 8. When the trailing edge of the original reaches the paper discharge roller 8, the paper discharge roller 8 temporarily stops and then reversely rotates so that the original is switched back. This is because if the original is discharged onto the discharge tray 21 with the discharge roller 8 facing upward, the original is discharged in a surface order different from the surface order set on the document tray 20. This is to prevent it.

  The document transported in the switch bank is discharged with the document surface facing down on the paper discharge tray 21 via the second registration roller 4, the first transport roller 5, the reading roller 7, the second transport roller 6 and the paper discharge roller 8. Is done. However, when the original passes through the reading position R, the original is not read.

  Here, the ADF 100 is provided with a plurality of sensors 10, 11, 12, 13, 14, and 15 for detecting document jam, document presence / absence, document transport position, and the like. Specifically, the sensor 10 is a post-separation sensor, the sensor 11 is a registration roller front sensor, the sensor 12 is a lead sensor, the sensor 13 is a paper discharge sensor, the sensor 14 is a document detection sensor, and the sensor 15 is a document length detection sensor.

  The reader unit 200 optically reads an image on the front side or the back side of a document, photoelectrically converts the read image, and outputs it as image data. The reader unit 200 includes an ADF original platen glass (hereinafter referred to as an ADF platen) 201 and a book original platen glass (hereinafter referred to as a book platen) 202. The reader unit 200 includes a scanner unit 209, a plurality of mirrors 205 and 206, a lens 207, a CCD sensor 208, and a reference white plate 211. In the scanner unit 209, two lamp units (linear light sources) 203 and 210 and a mirror 204 are incorporated.

  In the reader unit 200, when an image of a document is read using the ADF 100 (flow-reading mode), the scanner unit 209 is moved below the ADF platen 201 and stopped. The scanner unit 209 reads an image on the original when the original conveyed by the ADF 100 passes the reading position R.

  Further, it is possible to place a document on the book platen 202 and read an image of the document (fixed reading mode). In this case, the scanner unit 209 is moved from the document setting reference (not shown) in the sub-scanning direction, and the document placed on the book platen 202 is scanned by the movement of the scanner unit 209. By this scanning, the image on the original is read.

  When reading a document, the lamp units 203 and 210 are turned on, and light from the lamp units 203 and 210 is irradiated onto the document. Then, the reflected light from the document is input to the CCD sensor 208 via each mirror 204, 205, 206 and lens 207. The reflected light from the original input to the CCD sensor 208 is converted into an electrical signal by photoelectric conversion and output. The electrical signal output from the CCD sensor 208 is subjected to predetermined processing and output as image data.

  Although the case where the ADF 100 is an optional device has been described in the present embodiment, the image reading device in which the ADF 100 and the reader unit 200 are integrated may be used.

  Next, the control configuration of the ADF 100 will be described with reference to FIG. FIG. 2 is a block diagram showing a control configuration of the ADF 100 of FIG.

  As shown in FIG. 2, the ADF 100 is equipped with a CPU 800 as a central processing unit as a control means for controlling it. The CPU 800 is connected to a ROM (Read Only Memory) 801 and a RAM (Random Access Memory) 802. The ROM 801 stores a program for controlling the operation of the ADF 100 and data used for the control. The RAM 802 provides a work area for performing arithmetic processing when the CPU 800 executes control, a data area for temporarily holding the result of the arithmetic processing, and the like.

  CPU 800 has an input port and an output port. The input port includes various types of post-separation sensor 10, registration sensor 11, lead sensor 12, paper discharge sensor 13, document detection sensor 14, document length detection sensor 15, document width detection sensor 810 (not shown in FIG. 1). Sensor output is input. Various output sources of separation motor M1, paper supply motor M2, paper discharge motor M3, separation solenoid SL, and paper supply clutch CL are connected to the output port, and these drive sources are output via the output port. Driven and controlled based on the control signal.

  The CPU 800 performs serial communication with a CPU of the reader unit 200 described later via the communication path 803, and exchanges control data with the reader unit 200. That is, the CPU 800 controls the operation of the ADF 100 according to a program stored in the ROM 801 while communicating with the CPU of the reader unit 200.

  Next, the functional configuration of the reader unit 200 will be described with reference to FIG. FIG. 3 is a block diagram showing a functional configuration of the reader unit 200 of FIG.

  As shown in FIG. 3, the reader unit 200 includes a CPU 900. CPU 900 is connected to ROM 901, RAM 902 and operation panel 903. The ROM 901 stores a program for controlling the operation of the reader unit 200 and data used for the control. The RAM 902 provides a work area for performing arithmetic processing when the CPU 900 executes control, a data area for temporarily holding the result of the arithmetic processing, and the like. The operation panel 903 includes an operation unit having keys operated by the user, and a display unit that displays the contents of the set mode, the device state, and the like. The operation panel 903 outputs an instruction input by the user via the operation unit to the CPU 900 and displays the content output from the CPU 900 on the display unit.

  The CPU 900 generates and outputs control signals for controlling the operations of the optical system moving unit 302, the image reading unit 303, the image processing unit 304, and the lighting control unit 305. The optical system moving unit 302 includes a motor (not shown) for moving the scanner unit 209 and a circuit that drives the motor. The optical system moving unit 302 drives the motor based on a control signal from the CPU 900. The image reading unit 303 includes a CCD sensor 208 and a circuit for driving the CCD sensor 208, and drives the CCD sensor 208 based on a control signal from the CPU 900. The image processing unit 304 performs image processing including correction processing and A / D conversion on the analog signal from the image reading unit 303 based on a control signal from the CPU 900, and outputs image data. The lighting control unit 305 controls lighting of the lamp units 203 and 210 included in the document illumination unit 301 based on a control signal from the CPU 900.

  The CPU 900 is connected to the CPU 800 of the ADF 100 via the communication path 803. Further, the CPU 900 is connected to an external device (for example, a host computer) via the communication path 904, and control data is transmitted and received between the CPU 900 and the external device.

  In the present embodiment, the CPU 900 of the reader unit 200 and the CPU 800 of the ADF 100 are connected, and the CPU 800 controls the operation of the ADF 100 based on an instruction from the CPU 900. However, the present invention is limited to such a control configuration. Is not to be done. For example, it is possible to configure the CPU 900 to directly control the operation of the ADF 100 without providing the CPU 800 in the ADF 100.

  Next, the configuration of the lamp units 203 and 210 will be described with reference to FIG. FIG. 4 is a perspective view showing the external appearance of each of the lamp units 203 and 210 in FIG.

  In each of the lamp units 203 and 210, a plurality of LED elements 401 and 451 are arranged in a line at regular intervals. In the lamp unit 203, the light emitted from each LED element 401 is reflected and diffused by the reflecting plates 402 and 403, and is irradiated toward the document surface. In the lamp unit 210, the light emitted from each LED element 451 is reflected and diffused by the reflecting plates 452 and 453, and is irradiated toward the document surface.

  Each of the LED elements 401 and 451 is an LED element that emits light having the same wavelength region. In the present embodiment, a chip-type LED element that emits white light is used to enable reading of a color original. Moreover, it is also possible to use a discrete type LED element instead of the chip type LED element.

  Next, a method of arranging the LED elements 401 and 451 of the lamp units 203 and 210 according to chromaticity rank will be described with reference to FIGS. FIG. 5 is an arrangement diagram of the LED elements selected for each of the chromaticity ranks A and B in each of the lamp units 203 and 210. FIG. 6 is a diagram showing regions of the chromaticity ranks A and B on the chromaticity coordinates.

  In the present embodiment, as the LED elements 401 and 451, those selected so as to be suitable for each of the chromaticity ranks A and B are used. Here, in the LED elements suitable for each of the chromaticity ranks A and B, the respective color shading irregularities fall within the region on the chromaticity coordinates as shown in FIG.

  In the lamp unit 203, as shown in FIG. 5, the LED element of chromaticity rank A is arranged at the head position, and the LED element of chromaticity rank B is arranged subsequently. That is, LED elements with chromaticity rank A and LED elements with chromaticity rank B are alternately arranged. In the lamp unit 210, the LED element of chromaticity rank B is arranged at the head position, and subsequently, the LED element of chromaticity rank A is arranged. That is, LED elements with chromaticity rank B and LED elements with chromaticity rank A are alternately arranged.

  In this way, by alternately arranging LED elements having different chromaticity ranks A and B in the lamp units 203 and 210, the colors of the light emitted from the LED elements of the lamp units 203 and 210 are mixed. Further, due to a synergistic effect with the diffusion effect of the reflectors 402, 403, 452, and 453 of the lamp units 203 and 210, the color unevenness of the entire light source when reaching the original surface is reduced.

  Next, a circuit configuration for controlling the lighting current values of the LED elements of the lamp units 203 and 201 by the chromaticity ranks A and B by the lighting control unit 305 will be described with reference to FIG. FIG. 7 is a block diagram showing a circuit configuration for controlling the lighting current values of the LED elements of the lamp units 203 and 201 by the chromaticity ranks A and B by the lighting control unit 305 of FIG.

  As shown in FIG. 7, the lighting control unit 305 has two output terminals P and Q for outputting a lighting signal. Here, the output terminal P is connected to each LED element of chromaticity rank A of each lamp unit 203, 210, and the output terminal Q is connected to each LED element of chromaticity rank B of each lamp unit 203, 210. The Based on the control signal from the CPU 900, the lighting control unit 305 generates a corresponding lighting signal for each LED element of the chromaticity rank A and each LED element of the chromaticity rank B of each lamp unit 203, 210, Output via the corresponding output terminals P and Q. This lighting signal is a signal including a lighting current value for each LED element of chromaticity rank A and each LED element of chromaticity rank B of each lamp unit 203, 210.

  In the present embodiment, the CPU 900 is configured to perform lighting and lighting current control of the lamp units 203 and 210 via the lighting controller 305. Alternatively, the CPU 900 may be configured to directly perform lighting and lighting current control of the lamp units 203 and 210.

  Next, color unevenness correction processing for the lamp units 203 and 210 by the CPU 900 of the reader unit 200 will be described with reference to FIG. FIG. 8 is a flowchart showing the procedure of the unevenness correction process for the lamp units 203 and 210 by the CPU 900 of the reader unit 200 of FIG. The procedure shown in the flowchart of FIG. 8 is executed by the CPU 900 according to a program stored in the ROM 901.

  As shown in FIG. 8, the CPU 900 first drives the optical system moving unit 302 so as to move the scanner unit 209 below the reference white plate 211 (step S801). Subsequently, the CPU 900 controls the lighting control unit 305 so that the LED elements 401 and 451 of the lamp units 203 and 210 are lit at a preset lighting current value (step S802). Then, the CPU 900 controls the image reading unit 303 and the image processing unit 304 so as to capture the light reflected from the reference white plate 211 (light from each of the lamp units 203 and 210) as image data (step S803). The image data is taken into the CPU 900 via the image processing unit 304.

  Next, the CPU 900 analyzes the chromaticity on one line in the main scanning direction based on the image data (step S804). Then, the CPU 900 detects a state of occurrence of uneven coloring in the main scanning direction based on the analysis result. Specifically, when it is detected that uneven coloring occurs periodically in the main scanning direction, the LED of any chromaticity rank among the LED elements of each chromaticity rank of the lamp units 203 and 210. It is detected whether the color component (light quantity) of the element is insufficient. Further, an insufficient amount of the color component (light quantity) is detected.

  Next, the CPU 900 increases the lighting current value for the LED element of the chromaticity rank that is detected as having insufficient color component (light amount) based on the detected short amount of color component (light amount). The lighting control unit 305 is controlled (step S805). That is, the light amount of the LED element having the chromaticity rank that is detected as having insufficient color components (light amount) is increased so that the color unevenness generated in the main scanning direction is reduced.

  Here, there is a case where the lighting current value for the LED element of the chromaticity rank detected as a color component (light quantity) is insufficient reaches a limit value that cannot be increased any more. In this case, based on the shortage amount of the detected color component (light amount), the lighting current value for the LED element having a chromaticity rank different from the chromaticity rank detected when the color component (light amount) is insufficient is calculated. The lighting control unit 305 is controlled so as to be small. That is, the light amount of the LED element having a chromaticity rank different from the chromaticity rank detected when the color component (light amount) is insufficient is reduced so that the color unevenness generated in the main scanning direction is reduced.

  Next, the CPU 900 controls the lighting control unit 305 to turn on the LED elements of the lamp units 203 and 210 again in a state where the lighting current value for the LED elements having the corresponding chromaticity rank is changed. (Step S806). Here, LED elements having chromaticity ranks other than the chromaticity rank whose lighting current value has been changed are lit with a preset lighting current value. Subsequently, the CPU 900 captures again the image data read from the reference white plate 211 by the image reading unit 303 (step S807). Then, the CPU 900 analyzes the chromaticity on one line in the main scanning direction based on the captured image data, and based on the analysis result, the color unevenness in the main scanning direction is corrected to a level within an allowable range. It is determined whether or not (step S808).

  When it is determined in step S808 that the color unevenness is corrected to a level within the allowable range, the CPU 900 stores the chromaticity rank of the LED element whose lighting current value is changed and the lighting current value in the RAM 902 ( Step S809). Then, the CPU 900 ends this process. On the other hand, when it is determined that the color unevenness is not corrected to a level within the allowable range, the CPU 900 determines that there is an abnormality in the lamp units 203 and 210 or the lighting control unit 305 and outputs an alarm. (Step S810). Here, the alarm to be output is, for example, a warning sound output via the operation panel 903 or a warning message displayed on the operation panel 903. Then, the CPU 900 ends this process.

  In the present embodiment, color unevenness correction processing is performed by the CPU 900. Instead, the image data when the reference white plate 211 is read is sent to an external device, and the external device analyzes the color unevenness on one line in the main scanning direction based on the image data, and based on the analysis result. Thus, the state of uneven coloring in the main scanning direction may be detected. In this case, the CPU 900 is notified from the external device whether the color component (light quantity) of the LED element of which chromaticity rank is insufficient and the insufficient amount.

  The CPU 900 changes the lighting current based on the notified content, and sends the image data when the reference white plate 211 is read again to the external device. Then, the external device performs analysis based on the image data, and determines whether or not the color unevenness in the main scanning direction is corrected to a level within the allowable range. This determination result is sent to the CPU 900 from the external device.

  The CPU 900 stores the chromaticity rank of the LED element whose lighting current value is changed and the changed lighting current value in the RAM 902 according to the determination result, or outputs an alarm.

  In the present embodiment, two lamp units 203 and 210 are used as light sources, but one lamp unit can also be used as a light source. The configuration of the lamp unit at this time is as shown in FIG. That is, in this lamp unit, similarly to the lamp unit 203, the LED element of chromaticity rank A is arranged at the head position, and subsequently, the LED element of chromaticity rank B is arranged. Thereafter, similarly, LED elements of chromaticity rank A and LED elements of chromaticity rank B are alternately arranged.

  In the present embodiment, LED elements having different chromaticity ranks are alternately arranged on the same straight line one by one. Instead, for example, a plurality of LED elements of chromaticity rank A are set as a group, a plurality of LED elements of chromaticity rank B are set as b group, and a group and b group are alternately arranged on the same straight line. It may be.

  As described above, by changing the lighting current value for each LED element of the lamp unit according to the chromaticity rank, it is possible to correct the color unevenness of the light emitted from the lamp unit to be reduced. As a result, it is possible to irradiate the original with light with less color unevenness and obtain good read image data.

  In the present embodiment, an example of a single image reading apparatus has been described. However, similarly, good read image data can be obtained also in a copying machine, a multi-function peripheral (MFP), or the like equipped with this image reading apparatus. .

1 is a longitudinal sectional view schematically showing a configuration of an image reading apparatus according to an embodiment of the present invention. It is a block diagram which shows the control structure of ADF100 of FIG. It is a block diagram which shows the function structure of the reader part 200 of FIG. It is a perspective view which shows the external appearance of each lamp unit 203,210 of FIG. FIG. 3 is an arrangement diagram of LED elements selected for each chromaticity rank A and B in each lamp unit 203 and 210. It is a figure which shows the area | region of each chromaticity rank A and B on a chromaticity coordinate. It is a block diagram which shows the circuit structure for controlling each LED element of each lamp unit 203,201 according to chromaticity rank A and B, respectively by the lighting control part 305 of FIG. It is a flowchart which shows the procedure of the correction process of the nonuniformity with respect to each lamp unit 203 and 210 by CPU900 of the reader part 200 of FIG. It is a top view which shows typically arrangement | positioning of the LED element of a different chromaticity rank in the lamp unit applicable to the image reader which concerns on one embodiment of this invention. It is a figure which shows the general spectrum characteristic of an LED element.

Explanation of symbols

200 Reader unit 203, 210 Lamp unit 208 CCD sensor 209 Scanner unit 211 Reference white plate 301 Document illumination unit 302 Optical system moving unit 303 Image reading unit 304 Image processing unit 305 Lighting control unit 401, 451 LED element 402, 403, 452, 453 Reflector 900 CPU
901 ROM

Claims (9)

At least one linear light source in which a plurality of light emitting elements are linearly arranged;
Image reading means for reading reflected light from the original irradiated with light from the linear light source as image data;
Correction means for correcting color shading unevenness of the linear light source by controlling lighting current values of the plurality of light emitting elements,
The plurality of light emitting elements of the linear light source include light emitting elements having different chromaticity ranks, and the plurality of light emitting elements are respectively arranged adjacent to light emitting elements having different chromaticity ranks,
The image reading apparatus according to claim 1, wherein the correction unit varies a lighting current value for the plurality of light emitting elements for each color rank. A reference member,
The correction unit is obtained by reading the reference member irradiated with light of the plurality of light emitting elements with the image reading unit in a state where the plurality of light emitting elements are lit at a preset lighting current value. The color unevenness due to the linear light source is detected based on image data, and a lighting current value of a light emitting element having a corresponding chromaticity rank is changed based on the detection result. Image reading apparatus.   The correction means again turns on the light emitting elements of the corresponding chromaticity rank with the changed lighting current value and lights the light emitting elements of the other chromaticity ranks with the preset lighting current value. The color unevenness due to the linear light source is detected based on the image data obtained by reading the reference member irradiated with the light of the plurality of light emitting elements by the image reading means, and based on the detection result It is determined whether or not the color unevenness due to the linear light source is within an allowable range, and a lighting current value for each chromaticity rank is held or a warning is notified based on the determination result. The image reading apparatus according to claim 2.   The plurality of light emitting elements of the linear light source includes at least one light emitting element belonging to a first chromaticity rank and at least one light emitting element belonging to a second chromaticity rank different from the first chromaticity rank. The image reading apparatus according to claim 1, wherein: The number of the linear light sources is two;
Each of the linear light sources is disposed so as to be opposed to each other and so that the LED elements of one linear light source and the LED elements of the other linear light source opposed to each other have different chromaticity ranks. The image reading apparatus according to claim 1, wherein: A linear light source comprising: at least one linear light source in which a plurality of light emitting elements are arranged in a line; and image reading means for reading reflected light from a document irradiated with light from the linear light source as image data. The plurality of light emitting elements include light emitting elements having different chromaticity ranks, and each of the plurality of light emitting elements is adjacent to light emitting elements having different chromaticity ranks. A method,
A method for controlling an image reading apparatus, wherein the color unevenness of the linear light source is corrected by changing lighting current values for the plurality of light emitting elements for each color rank. The image reading apparatus includes a reference member,
Based on the image data obtained by reading the reference member irradiated by the light of the plurality of light emitting elements in a state in which the plurality of light emitting elements are lit at a predetermined lighting current value, by the image reading unit, 7. The method of controlling an image reading apparatus according to claim 6, further comprising detecting color shading caused by a linear light source and changing a lighting current value of a light emitting element having a corresponding chromaticity rank based on a result of the detection. .   Again, the light emitting elements of the corresponding chromaticity rank are turned on with the changed lighting current value and the light emitting elements of the other chromaticity ranks are turned on with the predetermined lighting current value. Color unevenness due to the linear light source is detected based on image data obtained by reading the reference member irradiated with light by the image reading means, and color tone due to the linear light source is detected based on the detection result. 8. The image according to claim 7, wherein it is determined whether or not the unevenness is within an allowable range, and a lighting current value for each chromaticity rank is held or a warning is notified based on a result of the determination. A method for controlling a reader.   An image forming apparatus comprising the image reading apparatus according to claim 1.

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