JP2007235441A - Image reading device and image formation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform such selection when a reading operation is made possible without the influence of failure by changing a reading mode even when the abnormality of a light emitting element is generated. <P>SOLUTION: This image reading device where light emitting elements in a plurality of colors are used as a light source, and a color reading mode and a monochromatic reading mode are set is configured to control the switching of the color reading mode to the monochromatic reading mode before performing a reading operation in the color reading mode when it is detected that any of the plurality of light emitting elements is abnormal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image reading apparatus using light emitting elements of a plurality of colors as a light source and an image forming apparatus including the image reading apparatus.

  A light source for reading a document is used in the image reading apparatus. An image reading apparatus using a light emitting element such as a light emitting diode (LED) as the light source is compatible with both color and monochrome. What can be done has been proposed. In the case of color reading, the color image signal is obtained by controlling lighting of each color using light emitting elements of three colors of R (red), G (green), and B (blue), and obtaining a signal corresponding to each color. The document is read as follows.

  Also, during color reading, the amount of light at the time of reading the LED needs to be controlled because there is variation in the amount of light of the LED itself, and the amount of light at the time of reading is controlled to be constant. Yes.

  On the other hand, in the case of monochrome reading, a document is read as a monochrome image signal by detecting a signal corresponding to green by light emission of a single color, for example, one green color.

  In addition, in order to cope with an increase in reading speed, there arises a problem that the amount of light is insufficient in single color lighting. In response to this problem, when reading is performed by simultaneously lighting a plurality of color light emitting elements, the amount of light of only a specific color increases or the color balance between the light emitting elements is lost. There may be a problem that an image of a specific color cannot be read, and in order to adjust the color balance, the lighting time is controlled to make the light quantity of each RGB color constant.

  However, in the image reading apparatus using the LED light source as described above, there is a problem that a defective image is output when the LED is deteriorated or failed.

  Therefore, a method for detecting deterioration or failure of the LED has been proposed. For example, when an insufficient light amount due to deterioration or failure of an LED is detected, control is performed such that the light emission amount of the LED is adjusted by the adjusting means, control to compensate for the insufficient light amount is performed by another LED, or the reading operation is stopped as an error. Has been proposed (see Patent Documents 1 and 2).

Further, in an image reading apparatus using an LED array light source in which a large number of LEDs are arranged, a document reading operation is performed if the position of the abnormal LED is outside the range of the original, and if the position of the abnormal LED is within the range of the original, the LED is read. Has been proposed (see Patent Document 2).
JP-A-9-93432 JP 2004-64406 A

  However, in the image reading apparatus as described above, the reading operation is interrupted or stopped when the adjustment range of the light emission amount of the LED is exceeded or a failure is detected. The interruption / stop time increases, which is very inconvenient for the user.

  In the prior art described in Patent Document 2, it is described that the document reading operation can be continued even if there is an abnormal LED, but the color and monochrome reading modes are not considered. That is, although there is a case where the reading operation may be possible without being affected by a failure depending on the reading mode, the change of the reading mode is not described.

  The present invention has been made in such a background, and an object of the present invention is to perform such selection when a reading operation can be performed without being affected by a failure by changing the reading mode even if an abnormality of the light emitting element occurs. Another object of the present invention is to provide an image reading apparatus and an image forming apparatus.

  An image reading apparatus according to the present invention is an image reading apparatus having a color reading mode and a monochrome reading mode, an irradiating unit that irradiates a subject with a plurality of light emitting elements having different wavelength distributions, and light emitted from the subject by the irradiating unit. In the color reading mode, when the photoelectric conversion means for converting into electric charge, the abnormality detection means for detecting abnormality of the plurality of light emitting elements, and the abnormality detection means detect that any of the plurality of light emitting elements is abnormal Has a control means for performing control to switch to the monochrome reading mode before the reading operation is performed.

  When reading a monochrome original in the color reading mode, even if an abnormality occurs in one of the light emitting elements, reading in the monochrome reading mode may prevent reading failure. Even in the case of a color original, if reading is performed in the monochrome reading mode, reading defects may be reduced as compared with reading in the color reading mode.

  The control unit may automatically change the reading mode, or may switch from the color reading mode to the monochrome reading mode or not according to the operator's instruction received by the operating unit. It may be.

  In the monochrome reading mode, the control unit may perform the reading operation without switching the reading mode when the abnormality detecting unit detects that any of the plurality of light emitting elements is abnormal. Good. This is because the interruption / stop time of the apparatus is reduced by executing the reading operation even if an image defect occurs.

  By having an adjusting means for adjusting different irradiation times for the plurality of light emitting elements having different wavelength distributions, the light amount level by the plurality of light emitting elements is adjusted, the variation in the light quantity between them is prevented, and the balance is achieved. Can take. Accordingly, when the adjustment unit adjusts the irradiation time, any abnormality of the plurality of light emitting elements can be detected by the abnormality detection unit.

  An image forming apparatus according to the present invention includes the image reading apparatus according to the present invention and an image forming unit that records an image read by the image reading apparatus on a recording sheet.

  The present invention includes a plurality of light emitting elements having different wavelength distributions, and an image reading apparatus having a color reading mode and a monochrome reading mode changes the color reading mode to the monochrome reading mode when an abnormality of the light emitting element is detected. By changing, it is possible to prevent defective images as much as possible and reduce the interruption / stop time of the apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a facsimile machine. However, the present invention is not limited to the facsimile apparatus, and can be applied to an image reading apparatus and an image forming apparatus such as a printer or a digital copying machine using the image reading apparatus.

  FIG. 1 is a perspective view of the facsimile apparatus according to the present embodiment as viewed from the front, FIG. 2 is a perspective view thereof, and FIG. 3 is an enlarged perspective view of an image reading unit.

  First, an outline of the entire facsimile apparatus will be described. 1, 2, and 3, 101 is an apparatus main body, 102 is an ADF (auto document feeder) pressure plate that stacks a plurality of sheet originals D, separates and conveys them one by one, and 103 is the surface of the sheet original D and the originals. An image reading unit for reading image information of a book document on a table glass, 104 is a recording apparatus main body composed of an electrophotographic printer, 105 is an operation unit including a display unit and input keys, 106 is a document placement table, and 107 is a document. A table glass, 108 is a movable image sensor unit, and 109 is a flow-reading glass.

  In addition, 110 is an LED head unit, 111 is an image forming unit, 112 is a cassette paper feeding unit, and 113 is a recording sheet discharge unit configured to be capable of stacking a plurality of sheet materials P on the upper portion of the recording apparatus main body 104. , 114 is a cartridge cover unit, 115 is an ADF separation unit, 116 is a paper discharge conveyance unit, 117 is a document discharge unit, 118 is a document pressing plate for pressing a book document, 119 is an image reading unit 103 and a recording apparatus main body 104. , 120 is a control unit of the facsimile machine, 121 is a sheet document conveyance unit, 122 is a double-sided conveyance unit cover, 123 is a conveyance direction switching unit, 124 is a registration conveyance unit, and 125 is disposed inside the recording apparatus main body 104. MP (multi-paper) feeding unit 150 is a double-sided conveyance unit.

  First, reading of a book document will be described. The ADF pressure plate 102 is rotatably attached to the image reading unit 103 via a hinge unit 102a (FIG. 2). One hinge portion 102a is provided on each of the left and right sides of the back side of the apparatus (the left side is not shown), and can be opened and closed by lifting the front side of the ADF pressure plate 102 (see double arrows in FIG. 2). The hinge portion 102a can make the ADF pressure plate 102 stand still in an open state up to a predetermined angle (for example, 70 °) by a combination of a damper, a cam, and a spring member. When the ADF pressure plate 102 is opened, it is possible to set a document on the platen glass 107.

  The movable image sensor unit 108 of the image reading unit 103 irradiates light on an image information surface of a document from a light source including an LED and a resin light guide, and reflects light reflected on the image information surface with a SELFOC (trademark) lens. Image information is read by forming an image on a one-dimensional sensor element array. A specific configuration example will be described later with reference to FIG.

  As shown in FIG. 4, the movable image sensor unit 108 is movable in the left-right direction of the apparatus along the guide shaft 103c, and is moved to a desired position by a timing belt 103a, a drive pulley 103b, a drive motor (not shown), and the like. It is movable. In this case, it is supported by the guide shaft 103c via the carriage 103d and urged upward by the spring 103e. A spacer 108 a is interposed between the image sensor unit 108 and the document table glass 107. The image sensor unit 108 reads an image of an original placed on the original platen glass 107 within a predetermined range from the book reading range start position 107a (FIG. 1) to the book reading range end position 107b by moving at a constant speed. It has become.

  As clearly shown in FIG. 3, a white sheet (reference white plate) 109c is disposed on the lower surface of the jump table 109b that protrudes above the document table glass 107, and when the reading position of the image sensor unit 108 is below the white sheet 109c. Shading correction of the image sensor unit 108 is performed. When performing a so-called book scan in which the book is opened, the image sensor unit 108 passes through the lower part of the jump table 109b for each scan, so that shading correction can be performed for each scan. This is effective for reducing the influence of the light source of the movable image sensor 108 whose light amount changes according to the temporal change of the light source.

  The document pressing plate 118 is configured by stacking white sheets, sponges, and the like, and prevents the document placed on the document table glass 107 from floating. The document pressing plate 118 has a left end 118a extending to the left side of the book reading range start position 107a and a right end 118b extending to the right side of the book reading range end position 107b.

  Next, reading of the sheet document D will be described. The ADF separation unit 115 includes a pickup roller 115a disposed so as to be vertically movable by an actuator (not shown), a retard roller 115c that is pressed against the separation roller 115b and rotates in the reverse direction.

  First, the sheet document D stacked on the document table 106 with the front surface facing upward is pressed by lowering the pickup roller 115a, and sent between the separation roller 115b and the retard roller 115c, and the retard roller. The sheets are separated one by one by a separation roller 115b in pressure contact with 115c. Next, the U-turn paper path is conveyed along the document guide 121d by the reading and conveying roller 121c in pressure contact with the separation conveying rollers 121a and 121b pressed by a pressing spring (not shown).

  Next, the sheet original D is conveyed to the flow reading glass 109 and pressed against the flow reading glass 109 by a sheet original pressing plate 121e pressed by a biasing spring (not shown), and is brought into close contact with the sheet original reading position 109a. The image information on the front surface of the sheet document D is read. At this time, the image sensor unit 108 moves to the sheet document reading position 109a. Next, the sheet document D is returned to the ADF pressure plate 102 side by the jump table 109b and conveyed by the reading conveyance roller 121c in pressure contact with the reading conveyance roller 121f pressed by the pressing spring.

  Further, the paper is discharged onto the original paper discharge tray 117c by a paper discharge roller 117b in pressure contact with the paper discharge roller 117a pressed by the pressing spring. A read stamp 121g is arranged on the upstream side of the paper discharge roller 117b, and can be stamped on the surface of the sheet original D.

  As clearly shown in FIG. 2, the document placing table 106 is fixedly disposed on the ADF pressure plate 102, and the document placing table 106 is arranged in a direction perpendicular to the conveying direction of the sheet document D (in the width direction of the sheet document D). A slidable slider 106a is provided. Both sides of the sheet original D stacked on the original placing table 106 can be aligned by the slider 106a. A document length sensor 106b is provided on the document table 106, and the length of the set sheet document D can be detected. Further, the presence / absence and width of the sheet document D can be detected by a plurality of document width sensors 115d arranged in the width direction of the sheet document D in the ADF separation unit 115. A document size and a set direction can be detected by a combination of detection outputs of the document width sensor 115d and the document length sensor 106b.

  Further, as clearly shown in FIG. 3, the document feeder 121 is provided with a document feeding sensor 121 h and a document edge sensor 121 i. The document feeding sensor 121h detects that the sheet document D has been fed out from the ADF separation unit 115 and that the rear end of the sheet document D has passed. The document edge sensor 121i detects the passage of the leading and trailing edges of the sheet document D, and its output is used for reading timing control.

  As described above, in the image sensor unit 108 of the present embodiment, the original image is read by irradiating the original with the light source and causing the reflected light from the original to enter the sensor via the imaging optical system. Yes.

  FIG. 5 shows a specific configuration example of the image sensor unit 108 according to the present embodiment. The image sensor unit 108 includes an LED 10 that is a light emitting element, and a light guide 11 that extends in the width direction of the document and guides light emitted from the LED 10 to the document. In this configuration example, a pair of light guides 11 are provided along both sides of the SELFOC ™ lens array 12 that forms the imaging optical system. A sensor 13 is disposed immediately below the lens array 12, and image sensor constituent members are arranged and configured in the frame body 14.

  The LED 10 is fixed to one end in the longitudinal direction of the light guide 11, but one LED is provided at each of one end of one light guide 11 and the other end of the other light guide 11 in the illustrated example. Thus, it is provided on the opposite side between the two light guides 11 and has a point-symmetric arrangement with respect to the central axis C.

  The light emitted from each LED 10 travels while being repeatedly reflected in each light guide 11, and is emitted from the entire length of the light guide 4. The light emitted from the light guide 11 is applied to the book document on the document table glass 107 as shown in FIG. 6, and each reflected light enters the sensor 13 through the lens array 12.

  FIG. 7 shows the light amount distribution by the light guide / light source in the image sensor unit 108 in the present embodiment. In the figure, the light quantity distribution is indicated by a solid line with reference to the distance from the LED 10 on the one light guide 11 side, and the light quantity distribution on the other light guide 11 side is indicated by a dotted line. The light amount distribution of the image sensor unit 108 as a whole is obtained by adding the light amounts of the respective LEDs 10 as indicated by a one-dot chain line. That is, as shown in the figure, the amount of light from each LED increases and is averaged in the distance direction.

  According to the image sensor unit 108 of this embodiment, with respect to the two light guides 11 arranged in parallel as described above, the LED 10 is provided at the end on the opposite side of each light guide 11 to guide the light. A light intensity distribution in which the body and light source complement each other is obtained. Thereby, a good read image without unevenness can be obtained.

  The light source is composed of LEDs that emit light of a plurality of colors. The LED light source 10 includes R, G, and B3 LEDs when performing color reading.

  FIG. 8 shows a configuration example of a conventional image sensor unit. That is, a single light guide 4 and a single LED light source 3 disposed at one end of the light guide 4 are provided in the frame body 7, and a lens array 5 and a sensor 6 are provided. The image sensor unit in the present embodiment shown in FIG. 5 has a light guide and an LED light source that are duplexed compared to the configuration of FIG. Can be increased.

  Next, an image signal processing unit that processes an image signal output from the image sensor unit 108 will be described with reference to FIG. FIG. 9 is a block diagram of the image signal processing unit.

  The CPU (& memory) 24 controls the lighting time of the LED drive circuit. An analog signal output from the image sensor unit 108 is amplified by an AMP (& A / D) 23, converted from an analog signal to a digital signal, and stored in the memory 24. The digital data obtained in this way is rearranged into a signal of one line in the rearrangement circuit 40, and shading correction is performed in the shading correction circuit 41. Thereafter, the image is printed out by a printer via the I / F circuit 42 or is reproduced by a host computer or the like. Further, the CPU 24 is a CPU for calculating shading data and the like and controlling the image reading unit 103, and 26 is an LED common power supply circuit for lighting the LED 22. The operation unit 43 of the image reading apparatus displays the status of the image reading apparatus or accepts a reading command from the user. The LED drive circuit 25 receives power from the LED common power supply 26 and drives each LED of the image sensor unit 108 under the control of the CPU 24.

  Further, the CPU 24 calculates an optimum LED lighting time from the stored image data. Based on the image data at this time, a failure or abnormality of the LED is detected.

  FIG. 10 shows a configuration example of the LED drive circuit 25 in the present embodiment. A driver 30 including a constant current circuit 31 and a switch circuit 33 is connected to each of the LED R1, LED G1, LED B1, LED R2, LED G2, and LED B2 connected to the LED common power source 26, and the CPU ( & Memory) 24, each switch circuit 33 is controlled to adjust the light quantity of each LED.

The light quantity characteristics of the light source in the present embodiment will be described with reference to FIG. FIG. 11A shows a schematic configuration of the image sensor unit 108, and FIGS. 11B, 11C, and 11D show left and right R, G, and R when the left and right LEDs are turned on separately. The LED light quantity characteristic of B is shown. In the drawing, the solid line graph indicates the characteristics of the left light emitting element, and the broken line graph indicates the characteristics of the right light emitting element. In this embodiment, there are two sets of RGB LEDs as light-emitting elements, and the number of LEDs is six in total: three on the left side and three on the right side. Therefore, it is assumed that the color balance is adjusted by adjusting the light quantity with the adjustment points as two points A and B in the vicinity of both ends of the image sensor unit 108. The positions A and B are at equidistant positions from the LED light source 10, respectively. Here, an adjustment method when the RGB color balance is 1: 1: 1 is shown.
(1) Pay attention to the image data level at the adjustment point A, and adjust the left RGB.
(2) Pay attention to the image data level of the adjustment point B, and adjust the right RGB.
(3) The lighting time of all LEDs is set to a predetermined time (for example, maximum), and the image data levels at the adjustment points A and B are checked.
For example, at adjustment point A,
Left R: 205/255 Level Left G: 230/255 Level Left B: 215/255 Level At adjustment point B,
Right R: 235/255 level Right G: 225/255 level Right B: 210/255 When the level becomes the left R level 205, this LED remains at the maximum lighting time. The other LEDs are adjusted by shortening the lighting time so that the level is 205 at each adjustment point.

  In the case of the left R, since 205/230 = 0.891, adjustment is made so that the light is lit for 89.1% of the maximum lighting time.

  In addition, even if one LED at each point has a light amount level of 255/255, when the output exceeds the dynamic range of the sensor, accurate light amount adjustment between RGB cannot be performed. Therefore, once the lighting time for such over-powered LEDs is reduced by a predetermined ratio (for example, 1/2, 1/4, etc.) so that all the LEDs are within the dynamic range, Again, the lighting time is adjusted so that the light intensity levels of all the LEDs coincide at the lowest level.

  When the light quantity level of all the LEDs is over output, the lighting time of all the LEDs is adjusted so as to be, for example, 250/255 level. The numerical value “250” is a numerical value that is lower than 255 and close to 255, and does not necessarily need to be 250. When the light level of all LEDs exceeds the dynamic range after saturation, there is a method of reducing the lighting time of all LEDs in common and then adjusting to the lowest output level. However, the dynamic range is within the dynamic range of the sensor. In order to effectively use the range, a method of adjusting to a level close to 255 is preferable.

  FIG. 12 shows the light quantity characteristics when the LED light source 10 of the present embodiment is deteriorated or fails. It shows the light quantity characteristics when the image sensor unit is degraded or broken down in the longitudinal direction (main scanning direction).

  Similarly to the above, when acquiring the image level in each RGB at the adjustment point, the abnormality detection of the LEDs (check which of the total of six LEDs of the left RGB and the right RGB is abnormal) is performed. At the time of acquiring the image level in each RGB at the adjustment point, the image of the white sheet 109c is sampled. If the LED 10 is abnormal, the distribution of sample data is as shown in the figure. Since the amount of light is insufficient due to the abnormality of the LED 10, the luminance data of that portion is reduced.

  Then, the sample data is compared with a predetermined threshold Th, and if the sample data is smaller than the threshold Th, it is determined that the LED is abnormal (deterioration or failure).

  Here, the predetermined threshold Th is a value that guarantees sufficient luminance so that the output image does not become a dropout color or density abnormality. The LED is considered to be abnormal with respect to the adjustment point of the luminance data, and the position and image data are detected and stored in the memory 24. At this time, an alarm is displayed on the operation unit 43 (105) that the LED is abnormal.

  Depending on the color of the LED as shown in FIG. 12, the threshold value Th may be different like the threshold values Th1, Th2, and Th3. When the LED light amount is lower than the threshold value, a defective image such as a dropout color or a density abnormality may occur in the read image when reading the image. Therefore, when the reading mode is the color mode, an alarm is displayed on the operation unit as shown in FIG. Thereby, the image reading operation is interrupted, and the user is allowed to select whether or not to continue the image reading operation in the monochrome mode.

  At this time, if the user is aware of the occurrence of a defective image and selects to continue the image reading operation, the image reading operation in the monochrome mode is performed when the image reading operation is continued. On the other hand, if the user selects to cancel the reading operation and the image reading cannot be continued, the processing is terminated without performing the image reading operation.

  If an abnormality of the LED is detected, the alarm display on the operation unit as shown in FIG. 17A is displayed until the LED is replaced even after the image reading is completed.

  Next, when the reading mode is the monochrome mode, an alarm is displayed on the operation unit as shown in FIG. Thereby, the image reading operation is interrupted, and the user is allowed to select whether or not to continue the image reading operation in the monochrome mode.

  At this time, if the user is aware of the occurrence of a defective image and selects to continue the image reading operation, the image reading operation in the monochrome mode is performed when the image reading operation is continued. On the other hand, if the user selects to cancel the reading operation and the image reading cannot be continued, the processing is terminated without performing the image reading operation.

  If an abnormality of the LED is detected, the alarm display on the operation unit as shown in FIG. 17A is displayed until the LED is replaced even after the image reading is completed.

  Hereinafter, the processing example in this Embodiment is demonstrated in detail with the flowchart of FIGS. These processes are realized by the CPU 24 reading and executing a program stored in the internal memory, and are executed automatically when the apparatus power is turned on, when necessary, or in response to a user instruction.

  The flowchart shown in FIG. 13 will be described. This figure shows a control sequence of processing at the time of turning on power or returning from sleep in the present embodiment.

  When the image reading apparatus is powered on or returned from sleep, offset adjustment is performed, and black data is shifted to the black side to a predetermined black level (S11).

  Next, the light quantity of each LED is adjusted (S12). The procedure for adjusting the light amount will be described later. After this light amount adjustment, the light amount (sensor level) of each LED is confirmed and stored in the memory. Next, the lamp is turned on under the white sheet (S13), and gain adjustment is performed (S14). That is, the AMP 23 amplifies the white sheet so that the white data matches the predetermined white data. Then, the lamp is turned off (S15), and offset adjustment is performed again (S16). This is because the offset state can be changed by gain adjustment.

  Next, black data is sampled with the lamp off, and black shading correction data is calculated and set for a predetermined area in the main scanning direction (S17). Next, the lamp is turned on (S18), white data of the white sheet is sampled, white shading correction data is calculated by the CPU 24 and set in the memory (S19). Next, the lamp is turned off (S20), and the light quantity (sensor level) of each LED acquired at the time of light quantity adjustment and stored in the memory is compared with predetermined threshold values Th1 to Th3 (S21). When the light quantity (sensor level) of each LED is larger than the threshold values Th1 to Th3 (N) (S22), it is determined that there is no abnormality in the LED, and this process is terminated.

  When there is an LED whose light amount (sensor level) is smaller than the thresholds Th1 to Th3 (S22, Yes), it is determined that the LED is abnormal, and the display screen in the operation unit as shown in FIG. Alarm a is displayed (S23), and this process is terminated.

  FIG. 14 shows a flowchart of the light amount adjustment processing of each LED of both LED light sources in the present embodiment.

  After the light amount adjustment process is started, first, the light amount level (sensor level) of each LED is sequentially confirmed at the adjustment points A and B (S1). Specifically, as described above, first, at the adjustment point A, the light amount levels of the left three LEDs are sequentially measured. Next, the light amount levels of the right three LEDs are sequentially measured at the adjustment point B. At this time, each LED is individually lit, and the lighting time is maximum (100%).

  Next, it is confirmed whether or not there is a LED light amount level of 255 level or higher (S2). (In fact, the sensor output is saturated even if the level is 255 level or higher, so the light amount level is 255 level.)

  If there are no more than 255 levels, the LED having the lowest light quantity level is found among all the LEDs (S3). Therefore, the lighting time ratio x [%] of each LED is calculated as follows (S4).

  Lighting time ratio x [%] = minimum level / LED light intensity level (1)

  As shown in FIG. 18, the lighting time ratio x [%] indicates the time ratio (c) with respect to the full lighting period (b) of the LEDs within the horizontal period of the horizontal synchronization signal (a).

  If at least one LED of 255 level or higher exists in step S2 (S2, Yes), the lighting time of the LED is reduced by a predetermined ratio p (1/2 in this example) to reduce the light amount level. Drop (S5). Therefore, it is confirmed whether the levels of all the LEDs are less than 255 (S6). If there is still an LED having a light level of 255 or more, the lighting time of the LED is further reduced by a predetermined ratio p (S7). In this example, if the same LED is reduced twice, the lighting time becomes 1/4 of the original. When the light quantity levels of all the LEDs are less than 255, the process proceeds to step S8.

  In step S8, it is checked whether or not all LEDs at the maximum lighting time obtained in step S2 are at the 255 level or higher. If it is determined that all the LEDs are not above the 255 level, the process proceeds to step S3. As in this case, the “LED light amount level” in the denominator of the above formula (1) when the process proceeds from step S8 to step S3 is the light amount level measured with the reduced lighting time. Further, the lighting ratio obtained for the LED whose lighting time is reduced and which is not the lowest level is a ratio of further reduction with respect to the reduced lighting time. For example, when the light quantity level of the LED whose lighting time is reduced to ½ is 200 levels and there is an LED with a light quantity level 190 lower than this, the former lighting ratio is (½) × (190/200). Calculated.

  If it is determined in step S8 that all LEDs are at the 255 level or higher, the lighting time is set with a predetermined light amount level (250 levels in this example) as a target (S9). That is, the lighting time of each LED is calculated as follows.

  Lighting time ratio = 250 / each LED light level (2)

  Each LED light amount level in the denominator of the expression (2) is not a measured light amount level but a light amount level of 255 levels or more obtained by calculation. In the calculation for obtaining the light quantity level, the measured light quantity level is multiplied by a coefficient (in the case of the number n, the reciprocal of p to the nth power) determined by the number of times of reduction in steps S5 and S7. For example, if the measurement result is 150 levels when 1/2 reduction is performed once, the actual light quantity level is 150 × 2 = 300 levels. In this case, the lighting time ratio is 250/300.

  Next, FIG. 15 shows a flowchart showing a processing example of the reading operation.

  When the start button of the reading operation is pressed by the user, the reading operation is started. In the image sensor unit that is previously positioned under the white sheet, a black sample is performed with the lamp turned off as black shading correction. The offset correction data is calculated and set (S31). Next, the lamp is turned on under the white sheet (S32), and the white sheet image is sampled as white shading correction, and the shading correction data is calculated from the sample data of the white sheet in the CPU 24 and set in the memory ( S33). If no abnormal LED is detected among the LEDs, it is determined that there is no abnormality in the LED (No in S34), a normal document reading operation is performed (S39), and this process is terminated.

  When the abnormal LED is detected (S34, Yes), in the color mode (S35, Yes), the alarm b display is performed on the screen display in the operation unit as shown in FIG. 17B (S36). In this case, a display indicating that an abnormality of the LED has occurred, confirmation of the change to the monochrome mode, and the possibility of occurrence of dropout color or density abnormality by the abnormal LED is performed. At this time, a display may be made to inform the original of what color the dropout color is red, green, blue or the like.

  Thereafter, it is checked whether or not the user has selected to continue or cancel the document reading (S37). If continuation is selected by the user pressing the “Yes” button or the like (S38, Yes), processing A (S43) is performed. Details of the processing A will be described later with reference to FIG.

  When the continuation is stopped by pressing the “No” button or the like (S38, No), the alarm a is displayed on the display screen in the operation unit as shown in FIG. S45), the process ends.

  If an abnormal LED has been detected in step S34, if it is not in the color mode (in the case of the monochrome mode) (S35, No), the occurrence of LED abnormality as shown in FIG. Then, an alarm display (alarm c display) for notifying the possibility of occurrence of dropout color or density abnormality by the abnormal LED is performed (S40). At this time, a display may be made to inform the original of what color the dropout color is red, green, blue or the like.

  Thereafter, it is checked whether or not the user has selected to continue or cancel the document reading (S41). When continuation is selected by pressing the “Yes” button by the user (S42, Yes), processing A (S43) is performed. Next, an original reading operation is performed (S44), an alarm a is displayed on the display screen in the operation unit as shown in FIG. 17A (S45), and this process is terminated.

  If cancellation is selected by pressing the “No” button in step S42, an alarm a is displayed on the display screen in the operation unit as shown in FIG. 17A without reading the document. (S45), this process ends.

  FIG. 16 is a flowchart showing details of the “process A” in step S44 of FIG.

  First, the lamp is turned off (S51), offset adjustment is performed (S52), then the lamp is turned on (S53), gain adjustment is performed (S54), the lamp is turned off (S55), and offset adjustment is performed again (S55). S56). Then, black shading correction is performed (S57), the lamp is turned on (S58), and white shading correction is performed (S59).

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made.

1 is a perspective view of a facsimile apparatus according to an embodiment of the present invention as viewed from the front. 1 is a perspective view of a facsimile according to an embodiment of the present invention. FIG. 3 is an enlarged perspective view of an image reading unit in the embodiment of the present invention. It is a figure which shows the internal structure of the image reading part in embodiment of this invention. It is a perspective view which shows the structural example of the image sensor unit in embodiment of this invention. It is sectional drawing which shows the structural example of the image sensor unit in embodiment of this invention. It is a figure which shows light quantity distribution by the image sensor unit in embodiment of this invention. It is a figure which shows the structural example of the conventional image sensor unit. It is a block diagram of the image signal processing unit in the embodiment of the present invention. It is the figure which showed the structural example of the LED drive circuit in embodiment of this invention. It is a figure which shows the light quantity characteristic in embodiment of this invention. It is a figure which shows the light quantity characteristic at the time of deterioration or failure of LED in embodiment of this invention. It is a figure which shows the flowchart of the control sequence at the time of power activation in the embodiment of this invention, and sleep return. It is a flowchart of the light quantity adjustment process of each LED of both LED light sources in embodiment of this invention. It is a flowchart showing the example of a process of the reading operation in embodiment of this invention. It is a flowchart showing the detail of "process A" of step S44 of FIG. It is a figure which shows the screen display in the operation part in embodiment of this invention. It is explanatory drawing of the lighting time ratio x [%] in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... LED light source 11 ... Light guide 12 ... Lens array 13 ... Sensor 14 ... Frame 24 ... Memory 25 ... Drive circuit 26 ... Common power supply 30 ... Driver 31 ... Constant current circuit 33 ... Switch circuit 40 Rearrangement circuit 41 ... Shading Correction circuit 42 ... I / F circuit 43 ... Operating unit 102 ... Pressure plate 102a ... Hinge unit 103 ... Image reading unit 103a ... Timing belt 103b ... Drive pulley 103c ... Guide shaft 103d ... Carriage 103e ... Spring 104 ... Recording device body 106 ... Original Place table 106a ... Slider 106b ... Sensor 107 ... Document table glass 107a ... Book reading range start position 107b ... Book reading range end position 108 ... Image sensor unit 108a ... Spacer 109 ... Sink reading glass 109a ... Sheet document reading position 109b ... Jump table 109c ... white Sheet 115 ... Separation part 115a ... Pickup roller 115b ... Separation roller 115c ... Retard roller 115d ... Document width sensor 117a ... Paper discharge roller 117b ... Paper discharge roller 117c ... Document discharge tray 118 ... Document holding plate 118a ... Left end 118b ... Right end 121 ... sheet document conveying sections 121a, 121b ... separation conveying roller 121c ... reading conveyance roller 121d ... document guide 121e ... sheet document pressing plate 121f ... reading conveyance roller 121g ... stamp 121h ... document feeding sensor 121i ... document edge sensor

Claims (11)

In an image reading apparatus having a color reading mode and a monochrome reading mode,
Irradiating means for irradiating a subject with a plurality of light emitting elements having different wavelength distributions;
Photoelectric conversion means for converting light from the subject by the irradiation means into charges;
An abnormality detecting means for detecting an abnormality of the plurality of light emitting elements;
In the color reading mode, when the abnormality detecting unit detects that any of the plurality of light emitting elements is abnormal, a control unit that performs control to switch to the monochrome reading mode before performing the reading operation;
An image reading apparatus comprising:   The irradiating means has a light guide extending in the width direction of the document, and the plurality of light emitting elements are disposed once in the longitudinal direction of the light guide, and light from the light emitting elements passes through the light guide. The image reading apparatus according to claim 1, wherein the object is irradiated with light.   The control unit causes the reading operation to be performed without switching the reading mode in the monochrome reading mode when the abnormality detecting unit detects that any of the plurality of light emitting elements is abnormal. The image reading apparatus according to claim 1. Adjusting means for adjusting different irradiation times for the plurality of light emitting elements having different wavelength distributions;
The image reading apparatus according to claim 1, wherein when the adjusting unit adjusts the irradiation time, the abnormality detecting unit detects an abnormality of any of the plurality of light emitting elements.   The image reading apparatus according to claim 1, further comprising: a warning unit that issues a warning when any abnormality of the plurality of light emitting elements is detected by the abnormality detection unit.   The image reading apparatus according to claim 1, further comprising a display unit that performs display for identifying the light emitting element when the abnormality is detected by the abnormality detection unit.   7. The apparatus according to claim 1, further comprising an operation unit configured to receive an operation from an operator, wherein the control unit receives a document reading start or stop selection operation by the operation unit. Image reading apparatus.   8. The image reading apparatus according to claim 7, wherein the control unit switches whether to switch from the color reading mode to the monochrome reading mode or not according to an operator instruction received by the operation unit. .   The image reading apparatus according to claim 1, wherein the abnormality detection unit detects an abnormality of the light emitting element based on image data obtained by reading a reference white plate by the photoelectric conversion unit.   The image reading apparatus according to claim 1, wherein the irradiation unit is an LED that emits a plurality of lights having different wavelength distributions.   An image forming apparatus comprising: the image reading apparatus according to claim 1; and an image forming unit that records an image read by the image reading apparatus on a recording sheet.