JP2012178790A - Image reader and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue reading of a color original even if one light emitting element is detected to be abnormal.SOLUTION: An image reader 1 includes: a light source 41 having a plurality of LED emitting different luminous color light beams L; and a light source 42 having a plurality of LED with the same structure as the light source 41 and emitting simultaneously luminous color light beams which are the same as those which the light source 41 emits. If a light emission abnormality detecting section 62 detects that one first LED between two LED with the luminous color light beams of the same color is abnormal when power is supplied to the image reader, a light source driving section 53 extends light emission time of normal second LED with the same color as first LED. Shading correction is performed on image data with the color of first LED. Thus, the reading of the original at a color reading mode can be continued without deteriorating a level of image quality of image data on the original when first LED is abnormal.

Description

  The present invention relates to an image reading apparatus that uses a plurality of light emitting elements that emit different colored light as light sources, and an image forming apparatus including the image reading apparatus.

  A conventional image reading apparatus is an image reading apparatus that constitutes a part of, for example, an electrophotographic multi-function printer (hereinafter referred to as “MFP”). Have the function of outputting to various devices.

  In a conventional image reading apparatus, a plurality of light emitting elements that emit light of different emission colors are used as light sources, a color reading mode and a monochrome reading mode are provided, and any one of the plurality of light emitting elements is detected as abnormal. In such a case, control is performed to switch from the color reading mode to the monochrome reading mode before performing the reading operation. Japanese Patent Application Laid-Open No. H10-228688 describes such an image reading device technology.

JP 2007-235441 A

  However, the conventional image reading apparatus has a problem in that color reading of a color original cannot be continued when one of the light emitting elements that emit light of different colors is abnormal. It was.

  An image reading apparatus according to the present invention includes a first light source having a plurality of light emitting elements that emit different emission color lights on a document on which an image is formed, and a plurality of light emitting elements having the same configuration as the first light source. A second light source that simultaneously emits the same emission color light as the emission color light emitted by the first light source, and reflected light or transmitted light from the document, and receives image data of an electrical signal An imaging element that converts and outputs, a light emission abnormality detection unit that detects abnormality of the light emitting element of the first and second light sources, and a first in the first or second light source in which the abnormality is detected A light source driving unit configured to change a light emission time of the second or first normal second light emitting element having the same color as the emitted color light of the light emitting element and drive the light emitting element;

  Furthermore, in the image reading apparatus of the present invention, the first white reference data of the emission color light of the second light emitting element whose light emission time is changed by the light source driving unit, and the light emission of the first light emitting element. A white reference data calculation unit that calculates second white reference data of the emission color light of all the light emitting elements other than color light; the second white reference data calculated by the white reference data calculation unit; A virtual white reference data calculation unit that calculates virtual white reference data of the emission color light of the first light emitting element based on a first correction coefficient; the virtual white reference data; and the first white reference data; A correction coefficient calculation unit that obtains a second correction coefficient for the image data, and a correction unit that corrects the image data based on the second correction coefficient.

  The image forming apparatus of the present invention includes the image reading device, a developing device that forms a visible image from the image data received from the image reading device, a transfer unit that transfers the visible image to a printing medium, and the printing medium. And a fixing unit for fixing the visible image transferred to the printer.

  According to the image reading apparatus and the image forming apparatus of the present invention, when the power is turned on or when returning from the power saving mode, the light emission abnormality detecting unit detects the abnormality of the light emitting element and has the same color as the light emitting element that has detected the abnormality. The color of the original is read by extending the light emission time of the other light emitting elements. Further, predetermined correction is performed on the read image data. Therefore, even if one light emitting element is abnormal, there is an effect that color reading of a color original can be continued without degrading the image quality of image data.

FIG. 1 is a functional block diagram showing an image reading apparatus according to the first embodiment of the present invention. FIG. 2 is a configuration diagram illustrating the image reading apparatus according to the first embodiment of the present invention. FIG. 3 is a schematic configuration diagram showing the reading unit in FIG. FIG. 4 is a block diagram showing the correction coefficient storage unit in FIG. FIG. 5 is a block diagram showing the light emission abnormality detecting unit in FIG. FIG. 6 is a block diagram showing the white reference data calculation unit in FIG. FIG. 7 is a block diagram showing the virtual white reference data calculation unit in FIG. FIG. 8 is a block diagram showing the shading circuit in FIG. FIG. 9 is a flowchart showing an operation of detecting an abnormality in LED light emission in the image reading apparatus of FIG. FIG. 10 is a flowchart showing an operation at the time of reading a color image in the image reading apparatus of FIG. FIG. 11 is a functional block diagram showing an image reading apparatus according to the second embodiment of the present invention. FIG. 12 is a block diagram showing the virtual white reference data calculation unit in FIG. FIG. 13 is a flowchart showing an operation at the time of reading a color image in the image reading apparatus of FIG.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Configuration of Example 1)
FIG. 2 is a configuration diagram illustrating the image reading apparatus 1 according to the first embodiment of the present invention.

  The image reading apparatus 1 includes an automatic document feeder (hereinafter referred to as “ADF”) 10 and a flat bed (hereinafter referred to as “FB”) 30. An ADF 10 is disposed on the top of the FB 30 so as to be openable and closable.

  The ADF 10 measures a document start table 11 for placing a document to be read, a document detection sensor 12 for detecting that a document is placed, a pickup roller 13, conveyance rollers 14 and 15, and a reading start timing. A reading position sensor 16, a document pressing plate 17, discharge rollers 18 and 19 for discharging the read document to a discharge tray 22, a document discharge sensor 20 for detecting that the document has been discharged, and a document are conveyed. And a stepping motor 21 for providing a driving force.

  The FB 30 includes a white reference plate 31, an FB original table 32 on which an original is placed, a contact glass 33 on which the white reference plate 31 and the FB original table 32 are formed, and a home sensor 34 that detects the position of the reading unit 40. A pulley 35, a conveyor belt 36, a stepping motor 37, and a reading unit 40 fixed to the conveyor belt 36.

  The conveyor belt 36 is stretched by a stepping motor 37 and a pulley 35, and is configured to move the reading unit 40 along the contact glass 33 by the rotation of the stepping motor 37. The home sensor 34 has a function of detecting that the reading unit 40 has moved to a predetermined position.

  The reading unit 40 moves to a document reading position (not shown) in the vicinity of the document pressing plate 17 of the ADF 10 by the transport belt 36 that operates in accordance with the rotation of the stepping motor 37, and scans the document transported from the document feed table 11. It has a function of reading and acquiring image data. Further, the reading unit 40 is moved along the FB document table 32 by the conveyance belt 36 that operates in accordance with the rotation of the stepping motor 37, and scans the document P placed on the FB document table 32 to scan the document. It has a function to obtain image data.

  The white reference plate 31 is read when acquiring output data of the reference image sensor at the time of shading correction for smoothing variations in the voltage output by the image sensor in the reading unit 40. It is arranged outside the reading range of the upper FB document table 32.

FIG. 3 is a schematic configuration diagram showing the reading unit 40 in FIG.
The reading unit 40 is a contact image sensor (hereinafter referred to as “CIS”) unit, and includes a first light source 41, a second light source 42, a light guide plate 43 and a rod lens 44 constituting an optical system. And a plurality of image sensors 45. Each imaging element 45 is composed of, for example, a complementary metal oxide semiconductor (hereinafter referred to as “CMOS”) or a charge coupled device (hereinafter referred to as “CCD”).

  The plurality of imaging elements 45 are arranged in the main scanning direction X, which is the longitudinal direction of the reading unit 40. Each of the plurality of imaging elements 45 corresponds to each pixel px in the main scanning direction of the read image data. Pixels corresponding to the plurality of image pickup elements 45a close to the light source 41 are referred to as close plural pixels pxa, and pixels corresponding to the image pickup element 45b close to the light source 42 are referred to as close plural pixels pxb.

  The light source 41 and the light source 42 include light emitting diodes (hereinafter referred to as “LEDs”) that are a plurality of light emitting elements that emit different colored light L, respectively. In the first embodiment, each of the light source 41 and the light source 42 includes three LEDs of red (hereinafter referred to as “R”), green (hereinafter referred to as “G”), and blue (hereinafter referred to as “B”). An example will be described. That is, the light source 41 is composed of an RLED 1 that emits R color, a GLED 1 that emits G color, and a BLED 1 that emits B color. The light source 42 includes an RLED 2 that emits R color, a GLED 2 that emits G color, and a BLED 2 that emits B color.

  When the color original P is read in the color reading mode, LEDs of three colors R, G, and B are sequentially emitted and read. When the image reading apparatus 1 reads a document, the color light L emitted from the six LEDs reaches the document P through the light guide plate 43. The reflected light from the document P is guided to the image sensor 45 through the rod lens 44, and the image sensor 45 receives this optical signal and converts it into an electrical analog signal.

FIG. 1 is a functional block diagram illustrating an image reading apparatus 1 according to the first embodiment of the present invention.
The image forming apparatus of the present invention includes an image reading device 1 and a printer 3. The printer 3 includes a developing device that forms a visible image from the image data received from the image reading device 1, a transfer unit that transfers the visible image to a print medium, and a fixing unit that fixes the visible image transferred to the print medium. It has.

  The image reading apparatus 1 is connected to a printer 3 via a data communication bus 2. The data communication bus 2 is configured by, for example, a USB (Universal Serial Bus) interface (hereinafter referred to as “I / F”).

  The image reading apparatus 1 includes a central processing unit (hereinafter referred to as “CPU”) 51 that controls the entire image reading apparatus 1. The CPU 51 has a function of controlling the entire image forming apparatus 1 based on various control programs stored in a read only memory (hereinafter referred to as “ROM”) 52 which is a nonvolatile storage device.

  The light source driving unit 53 is a driving circuit that drives on / off of the six LEDs in the light source 41 and the light source 42 of the reading unit 40, and includes, for example, a constant current circuit (not shown) and an opening / closing circuit (not shown). More specifically, the CPU 51 is configured to control the open / close circuit by pulse modulation (hereinafter referred to as “PWM”) to adjust the light quantity of the six LEDs. The image reading unit 54 has a function of generating analog image data based on the electrical signal output from the image sensor 45.

  An analog / digital conversion circuit (Analog Front End, hereinafter referred to as “AFE”) 55 has a function of converting analog image data generated by the image reading unit 54 into digital image data. The converted digital image data is stored in, for example, the RAM 59 as image data. The image data is composed of pixels px having color information such as color tone and gradation.

  A shading circuit 56 serving as a correction unit is a circuit that performs shading correction on image data. The shading circuit 56 has a function of performing shading correction on the read image data based on a predetermined formula.

  The image processing unit 57 has a function of performing image processing such as compression processing, gamma correction, and gradation conversion on the image data corrected by the shading circuit 56.

  The alarm unit 58 has a function of generating a notification sound to the user when an abnormal state is detected during the operation of the image reading apparatus 1. For example, when a light emission failure of two LEDs of the same color is detected, the alarm unit 58 has a function of generating a notification sound to the user.

  The RAM 59 is a storage unit used for temporary storage of image data and temporary storage of control data. The operation panel 60 has a function of displaying an operation instruction from the user and a state of the image reading apparatus 1. The conveyance control unit 61 drives the stepping motor 21 and the stepping motor 37 in accordance with instructions from the CPU 51 based on the on / off states of the document detection sensor 12, the reading position sensor 16, the document discharge sensor 20, and the home sensor 34. Is configured to do.

  The light emission abnormality detecting unit 62 has a function of detecting whether or not the six LEDs have abnormal light emission based on the digital output data of each pixel converted by the AFE 55.

  The white reference data calculation unit 63 turns on the LEDs of the light source 41 and the light source 42 before the reading unit 40 reads the document P, reads the white reference plate 31, and outputs a plurality of output data (hereinafter, referred to as a plurality of output data). The white reference data averaged using “bright output data”). This white reference data is obtained for each pixel.

  In the first embodiment, the white reference data is divided into first white reference data and second white reference data according to the state of LED emission of each color.

  The first white reference data is defined as follows. That is, when the light emission abnormality detection unit 62 detects an abnormality of one of the six LEDs, the light emission of the first LED that is the first light emitting element that is abnormal is turned off and the first LED is turned off. The light emission time of the second LED, which is a normal second light emitting element of the same color as the LED, is extended. White reference data calculated using a plurality of bright output data of each pixel acquired by the reading unit 40 reading the white reference plate 31 in a state where the light emission time is extended is referred to as first white reference data.

  The second white reference data refers to each pixel obtained by the reading unit 40 reading the white reference plate 31 when all the two LEDs (for example, GLED1 and GLED2) paired in the same color emit light normally. White reference data calculated using bright output data. The average data of each pixel acquired when the LED is off with respect to the white reference data is referred to as black reference data.

  The white reference data calculation unit 63 has a function of calculating white reference data that is an average value of bright output data sequentially input by color. The correction coefficient storage unit 64 changes the amount of second white reference data between any two colors of R, G, and B determined in advance by test evaluation (hereinafter referred to as “first correction coefficient”). ). This circuit is constituted by, for example, a line buffer.

  When the light emission abnormality detection unit 62 detects that the light emission of the first LED is abnormal, the virtual white reference data calculation unit 65, the second white reference data of a color different from the first LED, Using the first correction coefficient stored in the correction coefficient storage unit 64 corresponding to the color, the white reference data (hereinafter referred to as virtual white reference data) of the abnormal color of the first LED is calculated. It has a function.

  The correction coefficient calculation unit 66 includes the virtual white reference data of the first LED color that is abnormal calculated by the virtual white reference data calculation unit 65 and the first LED color calculated by the white reference data calculation unit 63. The first white reference data is used to calculate a second correction coefficient for correcting the image data.

  The I / F unit 67 has a function of controlling data transmission / reception with the data communication bus 2. The bus 68 is a communication path for transmitting and receiving commands output from the CPU 51 and read data generated by the image reading unit 54.

FIG. 4 is a block diagram showing the correction coefficient storage unit 64 in FIG.
The correction coefficient storage unit 64 includes a first correction coefficient 64a, a first correction coefficient 64b, and a first correction coefficient 64c. Hereinafter, the first correction coefficient 64a will be described as an example.

  The first correction coefficient 64a is data obtained by calculation from the second white reference data of G color and B color. Prior to the original reading operation, the reading unit 40 performs a shading operation, and calculates a first correction coefficient based on the acquired second white reference data for each of the G color and the B color.

For example, the G-color second white reference data of the n-th pixel of the reading unit 40 is X1, and the B-color second white reference data of the n-th pixel is X2. When the second white reference data of G color for the nth pixel is calculated from the second white reference data of B color, the first correction coefficient 64a is
First correction coefficient 64a = (X1-X2) / X1 + 1 (1)
It becomes.

When the second white reference data of B color for the nth pixel is calculated by the second white reference data of G color, the first correction coefficient 64a is
First correction coefficient 64a = (X2-X1) / X21-11 (2)
It becomes.

  The two types of first correction coefficients 64a calculated by Expression (1) and Expression (2) are all stored in the correction coefficient storage unit 64 before the image reading apparatus 1 is shipped. The first correction coefficient 64b and the first correction coefficient 64c obtained in the same manner are also stored in the correction coefficient storage unit 64.

FIG. 5 is a configuration diagram showing the light emission abnormality detection unit 62 in FIG.
The light emission abnormality detection unit 62 includes a portion corresponding to the light source 41 and a portion corresponding to the light source 42. The portion corresponding to the light source 41 has an RLED1 abnormality detection threshold 62a1, a GLED1 abnormality detection threshold 62a2, and a BLED1 abnormality detection threshold 62a3. Furthermore, the part corresponding to the light source 41 has comparison parts 62b1, 62b2, 62b3 and determination parts 62c1, 62c2, 62c3.

  Similarly, the portion corresponding to the light source 42 has an RLED2 abnormality detection threshold 62a4, a GLED2 abnormality detection threshold 62a5, and a BLED2 abnormality detection threshold 62a6. Furthermore, the part corresponding to the light source 42 has comparison parts 62b4, 62b5, 62b6 and determination parts 62c4, 62c5, 62c6.

  The output data of the abnormality detection thresholds 62a1 to 62a6 for the LEDs of the respective colors are input to the corresponding comparison units 62b1 to 62b6, respectively. Further, the comparison units 62b1 to 62b6 are configured to receive the output data S62-1 to 62-6 of the target pixel of each color. The output data of each comparison unit 62b1 to 62b6 is input to the corresponding determination unit 62c1 to 62c6.

The pixel of interest in FIG. 5 will be described using GLED 1 as an example.
At the stage of design evaluation, the white reference plate 31 is read in advance for a plurality of pixels pxa near the light source 41 having the GLED 1, and a pixel having the highest digital output level among the plurality of pixels 45a is set as a target pixel. When dimming is performed for the GLED 1, this target pixel is used as the dimming pixel. That is, if the digital output level of the target pixel satisfies a preset target value (for example, 230 level), the dimming of the GLED 1 is terminated.

  The GLED1 abnormality detection threshold 62a2 is a digital output level (for example, 100 level) for detecting an abnormality of the GLED1 determined in advance. When the dimming of the GLED 1 is performed, the output data S62-2 of the target pixel and the abnormality detection threshold 62a2 are compared by the comparison unit 62b2, and the output data S62-2 of the target pixel is set to the maximum dimming set in advance. Even when the time is used, when the abnormality detection threshold 62a2 (for example, 100 levels) is smaller, the determination unit 62c2 determines that the GLED1 is an output abnormality. Similarly, whether there is an output abnormality is determined for RLED1, BLED1, RLED2, DLED2, and BLED2 other than GLED1.

  The determination units 62c1 to 62c6 have a function of determining whether or not there is a light emission abnormality for the six LEDs and storing the result in a memory (not shown). When the CPU 51 determines that only one LED is abnormal based on the determination results of the determination units 62c1 to 62c6 stored in the memory, the one LED that is abnormal through the light source driving unit 53. The light emission time of the second LED that is not abnormal and the same color as that of the (first LED) is extended.

  When two or more LEDs are abnormal based on the determination results of the determination units 62c1 to 62c6 stored in the memory, the CPU 51 emits a notification sound to the user via the alarm unit 58 and the operation panel. The display unit 60 (for example, LCD; Liquid Cristal Display) displays a light emission abnormality.

FIG. 6 is a block diagram showing the white reference data calculation unit 63 in FIG.
The white reference data calculation unit 63 includes an R color white reference data calculation unit 63a, a G color white reference data calculation unit 63b, and a B color white reference data calculation unit 63c. Since the three white reference data calculation units 63a to 63c have the same configuration, the white reference data calculation unit 63b for G color will be described as an example.

  The white reference data calculation unit 63b for G color includes an adder and a divider circuit (not shown) for calculating the first white reference data or the second white reference data for G color. The white reference data calculation unit 63b is configured such that the bright output data S63b of each pixel of G color is sequentially input. The sequentially inputted bright output data S63b is integrated by an adder, and the integration result is divided by a divider to calculate G white reference data.

FIG. 7 is a block diagram showing the virtual white reference data calculation unit 65 in FIG.
The virtual white reference data calculation unit 65 includes a multiplication unit 65a. The virtual white reference data calculation unit 65 is a calculation unit that acquires virtual white reference data of an abnormal first LED color. A case where the GLED 1 is abnormal will be described as an example.

The virtual white reference data of G color is calculated by the second white reference data S65-1 of B color obtained by calculation by the white reference data calculation unit 63,
G-color virtual white reference data = B-color second white reference data S65-1
X First correction coefficient 64a (3)
It becomes.

  FIG. 8 is a block diagram showing the shading circuit 56 in FIG.

The shading circuit 56 includes a shading calculation unit 56a and a shading calculation unit 56b. The shading calculation unit 56a has a circuit configured based on the shading calculation formula shown in the following formula (4). This shading calculation unit 56a uses the image data of the two LEDs (for example, GLED1 and GLED2) of the same color and not abnormal, the second white reference data, and the black reference data to read based on Expression (4). Shading correction is performed on image data.
PIXn ′ = ((PIXn) − (Dn)) × 255 / ((Wn) − (Dn))
... (4)
However,
PIXn ′: the nth pixel of the reading unit 40 after shading correction
Original image data
PIXn: nth pixel of the reading unit 40 before shading correction
Document image data;
Wn: Second white reference data of the nth pixel of the reading unit
Dn: black reference data of the nth pixel of the reading unit
255: Maximum output level when AFE55 outputs 8 bits
data

The shading calculation unit 56b is a shading correction circuit that is used when the light emission abnormality detection unit 62 detects that one of the two LEDs of the same color is abnormal. This circuit is configured based on the following equation (5). Based on Expression (5), shading correction is performed on the document image data.
PIXn ′ = ((PIXn + Δ1n) − (Dn)) × 255
/ ((Wn ′) − (Dn)) (5)
However,
Wn ′: virtual white reference data of the nth pixel of the reading unit 40
Δ1n: second correction coefficient of the nth pixel of the reading unit 40
Δ1n is calculated by the correction coefficient calculation unit 66 based on the following equation (6).
Calculated.
Δ1n = PIXn × (Wn′−Wn ″) / Wn ′ (6)
Wn ″: first white reference data of the nth pixel of the reading unit 40.

(Operation of Example 1)
FIG. 9 is a flowchart showing an operation of detecting an LED light emission abnormality in the image reading apparatus 1 of FIG.

  In step S1, the user presses a power switch (not shown) of the image reading apparatus 1 or a power saving mode key (not shown). In step S <b> 2, the image reading apparatus 1 performs a calibration operation (for example, register setting of the CPU 51, operation confirmation of the stepping motors 21 and 37 and a series of sensors).

  In step S <b> 3, after the calibration operation is confirmed, the image reading apparatus 1 drives the stepping motor 37, and the reading unit 40 is conveyed under the white reference plate 31 by the rotation of the stepping motor 37. When the reading unit 40 reaches the white reference plate 31, the light source driving unit 53 emits six LEDs, that is, the RLED1, GLED1, and BLED1 of the light source 41 and the RLED2, GLED2, and BLED2 of the light source 42 in advance. Dimming is performed in a fixed order. For example, dimming is performed in the order of G, R, and B.

  In step S4, GLED1 and GLED2 are simultaneously dimmed. That is, when GLED1 and GLED2 emit light, the pixels of the reading unit 40 receive an optical signal that is reflected light from the white reference plate 31, and convert it into an analog signal. Next, the converted analog signal is converted into a digital signal via the AFE 55.

  The light emission abnormality detection unit 62 compares the level of the digital output data S62-2 of the target pixel of the GLED 1 with the stored abnormality detection threshold 62a2, and detects whether the GLED 1 has a light emission abnormality. The abnormality detection threshold 62a2 is a value determined in advance in a state in which GLED1 and GLED2 are turned on simultaneously. Further, the light emission abnormality detection unit 62 compares the level of the digital output data S62-5 of the target pixel of the GLED2 with the stored abnormality detection threshold 62a5, and detects whether or not there is a light emission abnormality in the GLED2. The abnormality detection threshold 62a5 is a value determined in advance in a state in which GLED1 and GLED2 are turned on simultaneously. The light emission abnormality detection unit 62 transmits the detected light emission states (normal or abnormal) of the GLED 1 and GLED 2 to the CPU 51.

  In step S5, the CPU 51 determines whether there is an abnormality in LED emission. When there is an LED emission abnormality (No), the process proceeds to step S7. In step S7, the LED light emission abnormality is stored in a memory (not shown). When there is no LED light emission abnormality (Yes), the process proceeds to step S6. In step S6, the light emission abnormality detection unit 62 performs dimming of the two LEDs via the light source driving unit 53 until dimming of the GLED1 and GLED2 is completed.

  When the dimming of GLED1 and GLED2 is completed, the dimming of RLED1 and RLED2 is performed next. Finally, dimming of BLED1 and BLED2 is performed. When the dimming of all the six LEDs is completed (Yes), the process proceeds to step S8.

  In step S8, the CPU 51 determines the light emission states of the six LEDs by the determination units 62c1 to 62c6 of the light emission abnormality detection unit 62 stored in a memory (not shown). As a result, when it is determined that only one LED (for example, GLED1) is abnormal (Yes), the process proceeds to step S9. In step S <b> 9, the CPU 51 turns off the light emission of the GLED 1 through the light source driving unit 53. In steps S10 and S11, the light emission abnormality detection unit 62 continues the normal dimming of the RLED 2 and extends the dimming time of the RLED 2 until the GLED 2 reaches a predetermined dimming level (for example, 200 level). Dimming like so. When the light control is finished (Yes), this process is finished.

  If it is detected in step S8 that two or more LEDs are abnormal, the process proceeds to step S12. In step S <b> 12, the CPU 51 outputs a notification sound to the user via the alarm unit 58 and displays a light emission abnormality on the LCD (not shown) of the operation panel 60.

  FIG. 10 is a flowchart showing an operation at the time of reading a color image in the image reading apparatus of FIG.

  The description will be made on the assumption that one LED (for example, GLED1) is detected to be abnormal with reference to FIG.

  In step S21, the user places the document P on the FB document table 32 of the image reading unit 40, sets a document pressing plate (not shown), and then presses a color reading start key (not shown). The image reading unit 40 starts color reading of the document P, and the reading unit 40 moves to below the white reference plate 31.

  In step S22, RLED1, RLED2, GLED2, BLED1, and BLED2 that are dimmed by the operation shown in FIG. 9 emit light. The reading unit 40 performs a shading operation for obtaining bright output data of each pixel in order to calculate the first white reference data of G and the second white reference data of B and R.

  In step S23, when the shading operation is finished, the reading unit 40 moves to a reading start position (not shown) of the document P, and performs a color reading operation along the sub-scanning direction Y of the document P.

  In step S24, when the document P is read, the white reference data calculation unit 63 uses the bright output data of each pixel acquired in step S22, and the first white reference data for G and the second white data for B. Reference data and R second white reference data are calculated.

  In step S25, the virtual white reference data calculation unit 65 calculates G virtual white reference data based on Expression (3). In step S <b> 26, the virtual white reference data calculation unit 65 calculates a second G correction coefficient for correcting the G image data, based on Expression (6).

  In step S27, when the reading unit 40 completes the reading operation of the document P, the shading circuit 56 performs shading correction of the B and R image data based on the equation (4), and G based on the equation (5). The shading correction is performed on the image data.

  In step S28, it is determined whether or not shading correction has been completed for all image data. When the shading correction of all the image data is completed (Yes), the image processing unit 57 performs image processing on the image data subjected to the shading correction. When the image processing is completed, the image data is transmitted to the printer 3 via the data communication bus 2 and the color reading operation of the image reading apparatus 1 is ended.

(Effect of Example 1)
According to the image reading apparatus of the first embodiment, when it is detected that one of the two LEDs of the emission color light L of the same color is abnormal, the light source driving unit 53 has detected the abnormality. The color of the original is read by extending the light emission time of the normal second LED having the same color as the first LED, and shading correction is performed on the image data of the abnormal color of the first LED. With this configuration, the image quality of the document image data when the first LED is abnormal can obtain the same level as the image quality when the first LED is normal. For this reason, even if one LED is abnormal, there is an effect that reading of a document in the color reading mode can be continued.

(Configuration of Example 2)
FIG. 11 is a functional block diagram illustrating an image reading apparatus 1A according to the second embodiment of the present invention. Elements common to those in FIG. 1 illustrating the first embodiment are denoted by common reference numerals.

  The configuration of the image reading apparatus 1A in the second embodiment is substantially the same as that in the first embodiment. The difference between the second embodiment and the first embodiment is that the configuration of the virtual white reference data calculation unit 65A is different from the virtual white reference data calculation unit 65 of the first embodiment. Other configurations are the same as those of the first embodiment.

  In the virtual white reference data calculation unit 65 according to the first embodiment, the second white reference data of the arbitrary emission color light L different from the emission color light L of the LED in which the abnormality is detected, and the first correction coefficient are used. By calculating, the virtual white reference data of the emission color light L of the first LED that was abnormal is acquired.

  On the other hand, in the second embodiment, in order to further improve the accuracy of the virtual white reference data, the virtual white reference data calculation unit 65A uses the second color different from the emission color light L of the LED in which the abnormality is detected. The virtual white reference data of the emission color light L of the first LED that is abnormal is obtained using the white reference data of 2. That is, the first calculation result is calculated based on one second white reference data of the two second white reference data and a first correction coefficient related to the one second white reference data. Further, the second calculation is performed based on the other second white reference data of the two second white reference data and the first correction coefficient related to the other second white reference data. A result is calculated, and an average value of the first calculation result and the second calculation result is obtained and used as the virtual white reference data.

FIG. 12 is a block diagram showing the virtual white reference data calculation unit 65A in FIG.
The virtual white reference data calculation unit 65A includes a multiplication unit 65Aa, a multiplication unit 65Ab, and an averaging circuit 65Ac. For convenience of explanation, the role of the multiplication unit 65Aa, the multiplication unit 65Ab, and the averaging circuit 65Ac will be described using an example in which an abnormality of the GLED 1 is detected.

  The virtual white reference data for G color is calculated from the second white reference data for B color and the second white reference data for R color. For example, the multiplication unit 65Aa has a function of obtaining the first calculation result of G color by multiplying the second white reference data of B color and the first correction coefficient between G and B. The multiplication unit 65Ab has a function of multiplying the second white reference data of R color and the first correction coefficient between G and R to obtain the second calculation result of G color. The averaging circuit 65Ac has a function of obtaining the G-color shading correction virtual white reference data by inputting the first calculation result and the second calculation result and calculating the average value.

(Operation of Example 2)
FIG. 13 is a flowchart showing an operation at the time of reading a color image in the image reading apparatus 1A of FIG. 11, and steps common to the steps in FIG.

  The operation of the image reading apparatus 1A in the second embodiment is substantially the same as that in the first embodiment. The second embodiment is different from the first embodiment in that step S25 in the flowchart showing the operation of the first embodiment in FIG. 10 is replaced with step S25A. The other steps S21 to S24 and steps S26 to S29 are the same as in the first embodiment.

Steps S21 to S24 similar to those in the first embodiment are executed.
Assume that the GLED 1 is abnormal in step 25A, which is different from the first embodiment, as in the description of FIG. 10 of the first embodiment. When the reading unit 40 reads the document P on the FB document table 32, for example, the multiplying unit 65Aa multiplies the second white reference data of B color by the first correction coefficient between G and B to obtain the first. Calculate the result of.

  The multiplying unit 65Ab multiplies the second white reference data of R color and the first correction coefficient between G and R to obtain a second calculation result. The first and second calculation results are averaged by the averaging circuit 65Ac, and G-color shading correction virtual white reference data is acquired.

  Subsequently, steps S26 to S29 similar to those in the first embodiment are executed, and the present process ends.

(Effect of Example 2)
According to the image reading apparatus 1A of the second embodiment, the virtual white reference data calculation unit 65A uses the second white reference data of two colors different from the emission color light L of the LED in which the abnormality is detected, respectively. Virtual white reference data is obtained, and the calculation results are averaged to obtain shading correction virtual white reference data. For this reason, in addition to the effect of the first embodiment, there is an effect that the correction accuracy for the image data can be further improved.

(Modification)
The present invention is not limited to the above-described embodiments, and various usage forms and modifications are possible. For example, the following forms (a) and (b) are used as the usage form and the modified examples.

  (A) In the first and second embodiments, the image reading devices 1 and 1A connected to the printer 3 via the data communication bus 2 have been described. However, the image reading devices 1 and 1A and the printer 3 are configured integrally. It can also be applied to a machine or a facsimile machine.

  (B) In the first and second embodiments, the light emitting elements constituting the light sources 41 and 42 have been described as the light emitting elements that emit the three types of light emission color light R, G, and B, but are not limited thereto.

1, 1A Image Reading Device 41 First Light Source 42 Second Light Source 43 Light Guide Plate 45 Image Sensor
53 Light source drive unit 56 Shading circuit 62 Light emission abnormality detection unit 63 White reference data calculation unit 65, 65A Virtual white reference data calculation unit 66 Correction coefficient calculation unit

Claims (8)

A first light source having a plurality of light emitting elements that emit different light emission colors with respect to a document on which an image is formed;
A second light source having a plurality of light-emitting elements having the same configuration as the first light source, and simultaneously emitting the same emission color light as the emission color light emitted by the first light source;
An image sensor that receives reflected light or transmitted light from the original, converts the image data into electrical signal image data, and outputs the image data;
A light emission abnormality detector for detecting abnormality of the light emitting element of the first and second light sources;
Changing the emission time of the second or first normal second light emitting element of the same color as the emitted color light of the first light emitting element in the first or second light source in which the abnormality is detected; A light source driving unit for driving the light emitting element;
The first white reference data of the emitted color light of the second light emitting element, the light emission time of which has been changed by the light source driving unit, and the light emitting elements of all the light emitting elements other than the emitted color light of the first light emitting element. A white reference data calculation unit for calculating second white reference data of the luminescent color light;
A virtual white reference for calculating virtual white reference data of the emission color light of the first light emitting element based on the second white reference data calculated by the white reference data calculation unit and a predetermined first correction coefficient. A data calculator,
A correction coefficient calculator that obtains a second correction coefficient for the image data based on the virtual white reference data and the first white reference data;
A correction unit that corrects the image data based on the second correction coefficient;
An image reading apparatus comprising: The image reading device further includes:
The optical system for guiding the emitted color light emitted from the first and second light sources to the document and guiding the reflected light or transmitted light from the document to the imaging device. The image reading apparatus according to 1. The light emission abnormality detection unit,
The amount of light emitted from the plurality of light emitting elements of the first and second light sources when the image reading apparatus according to claim 1 or 2 is turned on or when the image reading apparatus returns from the power saving mode. 3. The image reading apparatus according to claim 1, wherein the light emitting element is detected to be abnormal when the adjusted light emission amount is less than a reference value. The second correction factor is
4. The virtual white reference data of the emitted color light of the first light emitting element and the first white reference data of the emitted color light of the second light emitting element are obtained. The image reading apparatus according to any one of the above. The correction unit is
The image reading apparatus according to claim 1, comprising a shading circuit. The virtual white reference data calculation unit
Select any one of the plurality of second white reference data acquired by the white reference data calculation unit, and relate to the selected second white reference data and the second white reference data The image reading apparatus according to claim 1, wherein the virtual white reference data of the first light emitting element is calculated based on a first correction coefficient to be calculated. The virtual white reference data calculation unit
Two second white reference data of the light emission color light different from the light emission color light of the light emitting element in which abnormality is detected is selected, and the second one of the selected second second white reference data is selected. A first calculation result is calculated based on the first white reference data and the first correction coefficient related to the one second white reference data, and the selected second second white reference A second calculation result is calculated based on the other second white reference data of the data and a first correction coefficient related to the other second white reference data, and the first calculation result The image reading apparatus according to claim 1, wherein an average value of the first calculation result and the second calculation result is obtained and used as the virtual white reference data. An image reading apparatus according to any one of claims 1 to 7,
A developing device for forming a visible image from the image data received from the image reading device;
A transfer portion for transferring the visible image to a print medium;
A fixing unit for fixing the visible image transferred to the print medium;
An image forming apparatus comprising:

Images