JP4986870B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus having an illumination light source in which a plurality of point light sources such as LEDs are arranged.

  Conventionally, as a light source for illuminating a document used in an image reading apparatus, a light source typified by a Xe fluorescent tube filled with Xe (xenon) gas has been used in many cases. However, since fluorescent tubes such as Xe fluorescent tubes are lit and driven by high-frequency AC driving, it is necessary to secure a space for placing an inverter that converts a DC voltage into an AC voltage in the image reading apparatus. In addition, since the luminous efficiency of the fluorescent tube is poor, a large amount of heat is generated from the inverter and the fluorescent tube, and a countermeasure against heat is required and appropriate power is required. Furthermore, the life of the fluorescent tube is relatively short, and the fluorescent tube viewed from the product is positioned as a replacement part.

  Therefore, due to recent technological innovations, LEDs having a light emission amount suitable for use as an image reading system have appeared, and it has become possible to realize an image reading apparatus having an illumination light source in which a plurality of LEDs are arranged (for example, , See Patent Document 1). For example, as shown in FIG. 15, an example in which 48 LEDs 801 are linearly arranged on a substrate 800 and are turned on to form an illumination light source is common.

In this case, all 48 LEDs 801 may be connected in series to a constant current circuit, but if the forward voltage of one LED is 3.3 V, a voltage of 3.3 × 48 = 158.4 V or more is applied. Needed and not realistic. Therefore, as shown in FIG. 16, the 48 LEDs 801 are divided into 6 LED blocks 901, and a drive circuit 902 for lighting the LED 801 of the LED block 901 is connected to each LED block 901. The drive circuit 902 includes a constant current circuit and supplies a desired current to the block 901. For example, when the forward voltage per LED 801 is 3.3V, the drive circuit 902 applies a voltage of 3.3 × 6 = 19.8V or more.
JP 2002-247296 A

  However, in the conventional image reading apparatus, when the drive circuit 902 fails, the LED 801 of the LED block 901 cannot be turned on, and therefore the LED block 901 cannot be used as an illumination light source. Therefore, if even one drive circuit 902 fails, a normal read image cannot be obtained until the failed part is repaired or replaced.

  An object of the present invention is to provide an image reading apparatus capable of obtaining a normal read image even if a failure occurs in a driving circuit of an illumination light source.

To achieve the above object, an image reading apparatus comprising, have a plurality of illumination light sources are arranged linearly in the main scanning direction, illuminating means for illuminating an original, said plurality of illumination sources are one by one connected to each of the image reading apparatus comprising: a plurality of driving circuit for lighting the connected lighting source, and a reading means for reading an image of the document from the illuminated document by said illuminating means Detecting means for detecting a malfunctioning drive circuit among the plurality of drive circuits; and an illumination light source connected to the malfunctioning drive circuit detected by the detection means among the plurality of illumination light sources , And switching means for connecting to a non-failed drive circuit among the plurality of drive circuits .

According to the present invention, the illumination source is connected to a drive circuit which has failed, is switched to connect to the drive circuit has not failed, even the failure to the drive circuit of the illumination light source is generated, the normal read An image can be obtained.

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

[First Embodiment]
FIG. 1 is a cross-sectional view showing an internal configuration of an image copying apparatus equipped with an image reading apparatus according to a first embodiment of the present invention.

  In FIG. 1, an image copying apparatus 1 is an electrophotographic system, and includes an image reading apparatus 2 and a printer 3. The image reading device 2 reads an image of a document and acquires image information. The printer 3 forms an image on the transfer material P based on the image information acquired by the image reading device 2.

  The printer 3 employs an intermediate transfer method, and includes an image forming unit 10, a paper feed unit 20, an intermediate transfer unit 30, a fixing unit 40, and a control unit (not shown). The image forming unit 10 includes four stations 10a, 10b, 10c, and 10d. Since the stations 10a, 10b, 10c, and 10d have the same configuration, the configuration of the station 10a will be described here.

  The station 10a includes a photosensitive drum 11a, a primary charger 12a, an exposure unit 13a, a developing device 14a, a cleaning device 15a, and a folding mirror 16a. A photosensitive drum 11a as an image carrier is pivotally supported at its center and is driven to rotate in the direction of an arrow. Opposing the outer peripheral surface of the photosensitive drum 11a, a primary charger 12a, an exposure unit 13a of an optical system as an exposure unit, a folding mirror 16a, and a developing device 14a are arranged in the rotation direction.

  The primary charger 12a applies a uniform charge amount to the surface of the photosensitive drum 11a. Next, the exposure unit 13a exposes the photosensitive drum 11a through a folding mirror 16a with a light beam such as a laser beam modulated according to the recording image signal, thereby forming an electrostatic latent image there.

  Further, the electrostatic latent image is visualized by a developing device 14a containing a developer (hereinafter referred to as “toner”). The developing devices 14a to 14d respectively store toners of four colors, yellow, cyan, magenta, and black.

  A visible image (developed image) visualized by the developing device 14a is transferred to an image transfer area Ta of an intermediate transfer belt 31 described later, which is an intermediate transfer member.

  The cleaning device 15a cleans the drum surface by scraping off toner remaining on the photosensitive drum 11a without being transferred to the intermediate transfer belt 31 downstream of the photosensitive drum 11a rotating and passing through the image transfer area Ta. . Through the above process, image formation with each toner is sequentially performed by the stations 10a to 10d.

  The paper feed unit 20 includes cassettes 21a and 21b, a manual feed tray 27, pickup rollers 22a, 22b and 26, a paper feed roller pair 23, a paper feed guide 24, and registration rollers 25a and 25b.

  The cassettes 21 a and 21 b and the manual feed tray 27 store the transfer material P. The pickup rollers 22a, 22b, and 26 feed the transfer material P one by one from the cassettes 21a and 21b and the manual feed tray 27. The paper feed roller pair 23 and the paper feed guide 24 convey the transfer material P fed from the pickup rollers 22a, 22b, and 26 to the registration rollers 25a and 25b. The registration rollers 25 a and 25 b send the transfer material P to the secondary transfer region Te in accordance with the image formation timing of the image forming unit 10.

  The intermediate transfer unit 30 includes an intermediate transfer belt 31, a drive roller 32, a driven roller 33, a secondary transfer counter roller 34, primary transfer chargers 35a to 35d, a secondary transfer roller 36, a cleaning blade 51, a waste toner box 52, And a registration sensor 60.

  The intermediate transfer belt 31 is opposed to the secondary transfer region Te across the belt 31 as a winding roller, a driving roller 32 that transmits driving to the intermediate transfer belt 31, a driven roller 33 that follows the rotation of the intermediate transfer belt 31, and the belt 31. The secondary transfer counter roller 34 is wound around. Among these, a primary transfer surface A is formed between the driving roller 32 and the driven roller 33. The driving roller 32 is coated with rubber (urethane or chloroprene) on the surface of the metal roller to prevent slippage with the belt 31. The drive roller 32 is rotationally driven in the direction of arrow B by a pulse motor (not shown).

  The primary transfer surface A is opposed to the stations 10a to 10d, and the photosensitive drums 11a to 11d are opposed to the primary transfer surface A of the intermediate transfer belt 31. Accordingly, the primary transfer areas Ta to Td are positioned on the primary transfer surface A. Primary transfer chargers 35 a to 35 d are arranged behind the intermediate transfer belt 31 in the primary transfer regions Ta to Td where the photosensitive drums 11 a to 11 d and the intermediate transfer belt 31 face each other.

  A secondary transfer roller 36 is disposed to face the secondary transfer counter roller 34, and a secondary transfer region Te is formed by a nip with the intermediate transfer belt 31. The secondary transfer roller 36 is pressed against the intermediate transfer belt 31 with an appropriate pressure. Further, downstream of the secondary transfer region Te on the intermediate transfer belt 31, a cleaning blade 51 for cleaning the image forming surface of the intermediate transfer belt 31 and a waste toner box 52 for storing waste toner are provided. .

  The fixing unit 40 includes a roller pair 41, a guide 43, an inner discharge roller 44, an outer discharge roller 45, and a discharge tray 48.

  The roller pair 41 includes a fixing roller 41a having a heat source such as a halogen heater inside, and a pressure roller 41b that is pressed against the fixing roller 41a. A heat source may also be provided inside the pressure roller 41b.

  The guide 43 guides the transfer material P to the nip portion of the roller pair 41. The inner discharge roller 44 and the outer discharge roller 45 guide the transfer material P discharged from the roller pair 41 to the outside of the apparatus. When an image forming operation start signal is issued from a control unit (not shown), feeding of the transfer material P is started from the paper feed stage selected according to the selected paper size or the like.

  Next, a description will be added in accordance with the operation of the image copying apparatus 1.

  When an image forming operation start signal is issued from a control unit (not shown), first, the transfer material P is sent out one by one from the cassette 21a by the pickup roller 22a. The transfer material P is guided between the paper feed guides 24 by the paper feed roller pair 23 and conveyed to the registration rollers 25a and 25b. At that time, the registration rollers 25a and 25b are stopped, and the leading edge of the paper hits the nip portion. Thereafter, the registration rollers 25a and 25b start rotating in accordance with the timing at which the image forming unit 10 starts image formation. The rotation of the registration rollers 25a and 25b is set so that the transfer material P and the toner image primarily transferred from the image forming unit 10 onto the intermediate transfer belt 31 exactly coincide with each other in the secondary transfer region Te. ing.

  On the other hand, in the image forming unit 10, the toner image formed on the photosensitive drum 11 d that is the most upstream in the rotation direction of the arrow B of the intermediate transfer belt 31 is primary-transferred by the primary transfer charger 35 d to which a high voltage is applied. Primary transfer is performed on the intermediate transfer belt 31 in the transfer region Td. The primarily transferred toner image is conveyed to the next primary transfer region Tc. Image formation is performed by delaying the time during which the toner images are conveyed between the image forming units 10, and the next toner image is transferred with registration (image position) aligned on the previous image. The same process is repeated for the primary transfer areas Ta and Tb of other colors, and the four-color toner images are primarily transferred onto the intermediate transfer belt 31.

  Thereafter, when the transfer material P enters the secondary transfer region Te and contacts the intermediate transfer belt 31, a high voltage is applied to the secondary transfer roller 36 in accordance with the passing timing of the transfer material P. Then, the four color toner images formed on the intermediate transfer belt 31 by the above-described process are collectively transferred onto the surface of the transfer material P. Thereafter, the transfer material P is accurately guided to the nip portion of the fixing roller pair 41 by the conveyance guide 43. The toner image is fixed on the paper surface by the heat of the fixing roller pair 41 and the pressure of the nip. The transfer material P is conveyed by the inner and outer paper discharge rollers 44 and 45 and discharged to a paper discharge tray 48 outside the apparatus.

  In this type of image copying apparatus, a mechanical attachment error between the photosensitive drums 11a to 11d and an optical path length error of the laser beam generated by the exposure units 13a to 13d are generated. Also, due to reasons such as optical path changes and warpage due to the ambient temperature of the LED, registration shifts of the color images formed on the photosensitive drums 11a to 11d, that is, color shifts (registration shifts) occur. In order to correct these errors and deviations, a registration sensor that detects registration deviation at a position downstream of all the image forming units 10 on the primary transfer surface A and before the belt 31 is folded back by the driving roller 32. 60 is provided.

  FIG. 2 is a cross-sectional view showing a schematic configuration of the image reading apparatus 2 in FIG.

  In FIG. 2, the image reading apparatus 2 includes a reading unit 510, an original table glass 503, a second mirror 506, a third mirror 507, a lens 508, an image sensor 509, a shading correction plate 511, a member 512, and a pressure plate 513. The reading unit 510 includes a document illumination lamp 501 and a first mirror 505.

  The image of the original 504 placed on the original platen glass 503 is illuminated by the original illumination lamp 501 and is connected to the image sensor 509 via the first mirror 505, the second mirror 506, the third mirror 507, and the lens 508. Image. As a result, the image sensor 509 reads the line image of the document 504.

  A reading unit 510 including the document illumination lamp 501 and the first mirror 505 moves in the direction of arrow C and sequentially reads line images. At this time, the second mirror 506 and the third mirror 507 are also moved in the direction of arrow C, and are driven by a drive system (not shown) so that the distance (optical path length) from the document surface to the image sensor 509 is constant.

  A sequence in which the document image of the document 504 is actually read with the above configuration will be described.

  When an original reading command is input by an operator (specifically, a copy button is pressed, etc.), the image reading apparatus 2 cannot read the reading unit 510 from the arrangement shown in FIG. It is moved in the direction of arrow D by the illustrated drive system. As a result, the reading position of the reading unit 510 is arranged directly below the shading correction plate 511.

  Next, the image reading apparatus 2 turns on the document illumination lamp 501 to illuminate the shading correction plate 511. The reflected light of the shading correction plate 511 is guided to the image sensor 509 via the first mirror 505, the second mirror 506, the third mirror 507, and the lens 508 as a line image of the shading correction plate 511.

The output signal for each pixel of the line image of the shading correction plate 511 read by the image sensor 509 is corrected so that the output level of all the pixels becomes a predetermined level by an image processing circuit (not shown). By this image processing, uneven illuminance of the document illumination lamp 501, a decrease in peripheral light amount of the lens 508, and uneven sensitivity of each pixel of the image sensor 509 are corrected, and uneven reading of the document image is corrected. When the shading correction process is completed, the reading unit 510 is further moved in the direction of arrow D by a drive system (not shown), and is disposed immediately below the member 512.

  Directly below the member 512 is a document image reading start position, and from this position, a driving system (not shown) accelerates the reading unit 510 in the direction of arrow C. The reading unit 510 is controlled so as to be driven at a constant speed at a predetermined speed until the reading position reaches the leading end of the original 504 that is pressed by the pressure plate 513 and maintains flatness.

  When the reading position of the reading unit 510 reaches the leading end of the document 504, the image sensor 509 starts reading the line images of the document 504 sequentially.

  A drive system (not shown) moves the reading unit 510 in the direction of arrow C while maintaining a constant speed, and stops reading after the reading to the end of the original 504 is completed. Thereafter, the drive system moves the reading unit 510 in the direction of arrow D to return to the home position shown in FIG. 2, ends a series of image reading, and waits for the next reading.

  This is the end of the description of the basic image reading operation of the image reading apparatus 2.

  By the way, the document illumination lamp 501 is composed of an LED substrate on which 48 white LEDs are linearly arranged. Next, the LED substrate constituting the document illumination lamp 501 will be described.

  FIG. 3 is a diagram showing a part of the configuration of the LED substrate included in the document illumination lamp 501 in FIG.

  In FIG. 3, the LED substrate 200 includes eight LED blocks. FIG. 3 shows only two of the LED blocks 101a and 101b. Each LED block includes six LEDs 201 connected in series. Therefore, the LED substrate 200 includes 48 LEDs 201.

  The LED blocks 101a and 101b are connected to drive circuits 104a and 104b via changeover switches 102a, 102b, 103a, and 103b, respectively.

  The drive circuits 104a and 104b are composed of constant current circuits. When the forward voltage per LED 201 is 3.3V, a voltage of 3.3 × 6 = 19.8V or more is applied to obtain a desired current. Is supplied to the LED blocks 101a and 101b. Accordingly, the drive circuits 104a and 104b turn on the LEDs 201 mounted on the LED blocks 101a and 101b.

  The drive circuits 104a and 104b connected to the LED blocks 101a and 101b can drive a maximum current of 40 mA, but a constant current drive of 20 mA is set as a standard for driving one LED block. It also has a current control function for finely adjusting the amount of light for each LED block.

  FIG. 4 is a diagram illustrating an example of a control circuit of the image reading apparatus 2 of FIG.

  In FIG. 4, the image reading apparatus 2 includes an LED substrate 200, a control circuit substrate 701, an LED drive circuit control unit 707, an image sensor 509, and an I / F circuit 708.

  The control circuit board 701 includes a CPU 702, an ASIC 703, a ROM 704, and a RAM 705, which are connected to each other via a system bus 706.

  The ASIC 703 is a large-scale integrated circuit that transmits / receives image processing such as shading correction and control signals to the main unit of the image reading apparatus 2 according to a command from the CPU 702. The ROM 704 stores a control program for the CPU 702. The RAM 705 is used as a calculation area by the CPU 702.

  The ASIC 703 is connected to an LED drive circuit control unit 707, an image sensor 509, and an I / F circuit 708. A line image of the document image sent from the image sensor 509 is input to the ASIC 703.

  The ASIC 703 is connected to an external device such as a printer (not shown) connected to the I / F circuit 708, performs image processing on the read document image, and sends an image signal to the external device.

  The LED drive circuit control unit 707 includes a total of eight circuits including, for example, the changeover switches 102a and 103a and the drive circuit 104a shown in FIG. The changeover switch constituted may be a mechanical changeover switch such as a micro relay, or a semiconductor switch constituted by a switching transistor or the like.

  Each drive circuit and each changeover switch are configured to receive control from the CPU 702 via the ASIC 703. The LED board 200 is connected to the LED drive circuit controller 707. As described above, the LED board 200 is composed of 8 circuits each having 6 LEDs as one block, and the LED board 200 and the LED drive circuit control unit 707 are connected with the structure shown in FIG. Yes.

  When all the LED blocks mounted on the LED substrate 200 are normally lit, the changeover switches 102a, 102b, 103a, and 103b have the changeover switches at the positions shown in FIG. Therefore, one LED block corresponds to one drive circuit on a one-to-one basis. At this time, if unevenness in the light quantity of each LED block can be confirmed during the shading correction process, the CPU 702 controls the LED drive circuit control unit 707 via the ASIC 703 to finely adjust the drive current set for each drive circuit. .

Here, the failure of the drive circuit 104 b, will be described a case where LED block 101b is no longer illuminated. In this case, in the LED block 101b, all six LEDs 201 are not turned on, and the original function as an image reading apparatus cannot be exhibited.

  5A and 5B are diagrams showing the relative relationship between the read levels of the LED blocks 101a and 101b and the shading correction plate 511 in FIG. 3, where FIG. 5A shows a normal time, and FIG. 5B shows a time when the drive circuit 104b has failed. .

  In FIG. 5A, after fine adjustment of the drive current, the reading level 601 of the shading correction plate 511 is a uniform reading level in the illumination range by the LED block group 101 including the LED blocks 101a and 101b.

In FIG. 5B, when the drive circuit 104b is faulty, the reading level 602 of the shading correction plate having a uniform white density becomes a low reading level at a location facing the LED block 101b. Thus, the image reading apparatus 2 detects a failure of the drive circuit 104b in the process of executing the shading correction process. When a failure of the drive circuit 104b is detected, a normal read image is not obtained even if the reading operation is performed as it is, and therefore the CPU 702 controls the image sensor 509 so as not to perform the reading operation. Further, the CPU 702 switches the changeover switches 102b and 103b in the LED drive circuit control unit 707 as illustrated in FIG. 6 via the ASIC 703.

  FIG. 6 is a diagram illustrating a configuration of the LED substrate 200 when the drive circuit 104b in FIG. 3 is faulty.

9, by switching the switch 1 02b, 1 03b, LED block 101b is connected to a drive circuit 104a which is operating normally. The drive circuit 104a drives and drives the LED blocks 101a and 101b. At the same time, the CPU 702 adjusts the drive current of the drive circuit 104 a in the LED drive circuit control unit 707 to 40 mA via the ASIC 703.

When the image reading apparatus 2 performs the shading correction again by the control of the control circuit board 701 as described above, the reading level of the shading correction plate 1211 is substantially as shown in FIG. Can continue.

  Also at this time, during the shading correction, each drive circuit performs fine adjustment of the drive current according to the amount of light emitted from each LED block, but the LED blocks 101a and 101b cannot be finely adjusted individually. Therefore, a slight amount of light amount unevenness may occur at the illumination locations of the LED blocks 101a and 101b. Although this unevenness in the amount of light is corrected by shading correction processing, there is a possibility that the image will be slightly deteriorated compared to the normal operation, but there is little difference in image quality in a high-contrast original such as a normal text original or illustration. I can say no.

  On the other hand, although the image reading operation can be continued, the fact that it is out of order does not change. Therefore, the user is made aware that there is a failure via the image reading apparatus 2, the connected printer, or an external device, and the user It is desirable to encourage the response. For example, control may be performed so that a message prompting the user to replace the failed LED board 200 is displayed on the display unit or the like.

  By the way, the drive circuits 104a and 104b need only have a drive capacity of 20 mA during normal operation, but the present invention has a drive capacity of 40 mA in consideration of failure. Although this seems to be over-specification as a constant current drive circuit, since it has a constant current circuit configuration of about 40 mA at most, there is almost no difference in circuit scale and cost between the 20 mA constant current drive circuit and the 40 mA drive circuit. . The power consumption of the LED substrate 200 as a whole is naturally equal between the normal state and the failure state, and has little influence on the power supply design of the constant current drive circuit.

  In addition, in the circuit configuration described in the first embodiment, it is not possible to turn on three or more LED blocks with a single drive circuit, but it is possible to cope with the failure of half of the LED blocks, which is a big problem in practice. It will not be. In addition, since the configuration of one drive circuit can be configured on a small scale, it can be configured at a reduced cost as a whole.

  As described above, the line image data of the original read by the configuration of FIG. 2 is sequentially sent to the printer 3, and the read image is formed by the printer 3.

According to the first embodiment, since the connection to the drive circuit 104 a of the LED block 101b is operating normally, when the drive circuit of the LED block has failed, it is possible to obtain a normal read image .

[Second Embodiment]
In the first embodiment, it is assumed that the driving circuit for driving one LED block has a standard of 20 mA, and that the specification has a maximum of 40 mA that can drive up to two LED blocks. did.

  However, a high-speed image reading apparatus using LEDs as illumination light sources requires a larger amount of light, and a constant current value that can drive up to two LED blocks may be increased. In this case, it is conceivable that the cost of the drive circuit is significantly increased. In the second embodiment, an example in which only one circuit among a plurality of drive circuits is configured as a drive circuit capable of driving a large current and the other drive circuits are configured with small-scale drive circuits will be described.

  FIG. 7 is a diagram showing a configuration of the LED substrate 200 according to the second embodiment of the present invention.

In FIG. 7, the LED substrate 200 includes an LED block group including LED blocks 101a, 101b, and 101c. LED blocks 101a, 101b, 101c, via select switch 1 02b, 102 c, 103b, the 103c, driving circuits 104a, 104b, are connected respectively to 104c.

  The drive circuit 104b connected to the LED block 101b and the drive circuit 104c connected to the LED block 101c are set with a constant drive current of 40 mA as a standard to drive one LED block. The same applies to five circuits (not shown).

  The topmost drive circuit 104a is a constant current drive circuit having a drive capability of a maximum of 320 mA so that eight LED blocks can be driven.

  In the above configuration, when the drive circuit 104b fails, the control circuit board 701 detects that the drive circuit 104b has failed as in the first embodiment. The control circuit board 701 switches the changeover switches 102b and 103b as shown in FIG. Thus, the drive circuit 104a is connected to the LED block 101a and the LED block 101b. At the same time, the control circuit board 701 switches the drive current of the drive circuit 104 to 80 mA.

  By the above control, the LED block 101b can be turned on, and the reading operation of the image reading apparatus 2 can be executed.

  Here, when the drive circuit 104c also fails, the control circuit board 701 detects that the drive circuit 104c has failed as in the first embodiment. The control circuit board 701 switches the selector switches 102b, 103b, 102c, and 103c as shown in FIG. Accordingly, the drive circuit 104a is connected to the LED block 101a, the LED block 101b, and the LED block 101c. At the same time, the control circuit board 701 switches the drive current of the drive circuit 104 to 120 mA.

  With the above control, the LED blocks 101b and 101c can be turned on, and the reading operation of the image reading apparatus 2 can be executed.

  According to the second embodiment, a normal read image can be obtained even if a failure occurs in the drive circuit of the illumination light source. Further, as long as the drive circuit 104 does not fail, the image reading operation can be continued no matter how many other drive circuits fail.

  In addition, by selecting one of the methods of the first embodiment or the second embodiment according to the balance between necessary specifications and costs, a circuit that meets the specifications and costs can be designed.

[Third Embodiment]
The technique described in the first embodiment or the second embodiment is a technique that guarantees the maximum reading range of the image reading apparatus at the time of failure, and sacrifices image quality for that purpose.

  In the third embodiment, an image reading apparatus provided with a degeneration mode that cannot cover the maximum reading range but can guarantee image quality even with a small size will be described.

  In the third embodiment, the image reading apparatus 2 does not include the changeover switch as described in the first or second embodiment, and the drive circuit is simply connected to the LED block in a one-to-one relationship. 8 circuits are provided.

  10A and 10B are diagrams for explaining timing signals transmitted by the image reading apparatus according to the third embodiment of the present invention. FIG. 10A shows a normal time, and FIG. 10B shows a time when the drive circuit 104b has failed. .

  In FIG. 10 (a), the LED block group 101 is composed of eight blocks including blocks 101a to 101c in which six white LEDs are connected in series, as in the first embodiment, and a total of 48 blocks. Has an LED.

  When all eight blocks emit light normally, the reading level 1101a of the shading correction plate 511 is a uniform reading level in the illumination range by the LED block group 101.

  A timing signal φSH1102 is input to the CCD sensor 509 of the image reading apparatus 2. φSH1102 is a line reset signal of the CCD sensor 509, and image signals are sequentially output from the first pixel at the timing of φSH1102.

  The timing signal ITOP1103a is an image destination signal sent to the printer. In the printer, the first pixel of the image signal of the CCD sensor 509 is recognized according to the timing of ITOP 1103a. Therefore, usually φSH1102 and ITOP1103a are synchronized, and the generation timing is almost the same. The printer recognizes the image range 1104a for one line and the effective image range 1105a, and sequentially processes the line-shaped effective image range 1104a to form one image.

In FIG. 10B, when the LED block 101b does not light up, the reading level 1101b of the shading correction plate having a uniform white density becomes a low reading level at a location facing the LED block 101b. As in the first embodiment, the control circuit board 701 detects a failure in the LED block 101b.

  At this time, the control circuit board 701 generates the timing signal ITOP1103b in accordance with the timing when the CCD sensor 509 recognizes the LED block 101c. At the same time, the effective image range 1105b corresponding to the LED blocks after the LED block 101c is notified to the printer, and the printer optimizes each control according to the notified effective image range 1105b.

  11A and 11B are diagrams showing an image sent from the image reading apparatus to the printer according to the third embodiment of the present invention, where FIG. 11A shows a normal time, FIG. 11B shows a timing signal after change, (C) shows after mask processing execution.

  FIG. 11A shows an image received by the printer when all the LED blocks 101 are lit, and shows a state in which a document image is normally reproduced.

  FIG. 11B shows an image received on the printer side when the LED block 101b is not lit, the above-described control is performed, and the output timing of the timing signal ITOP is changed. The effective image range is reproduced from the document area illuminated by the LED block 101c, and the image in the invalid image range is also sent to the printer. If the LED block 101a and the LED block on the left are also controlled to light, the area illuminated by those LED blocks is also formed as an image. The area of the LED block 101b that is turned off is a black image.

  An effective image area is notified from the image reading apparatus, and of course, it is possible to control the printer so that the invalid image area is not reproduced. However, since image processing such as the size of the copy paper selected on the printer side and enlargement / reduction by the printer is included, complicated calculation is required for information processing of the image data actually formed from the notified effective image area information. Cost. On the other hand, on the image reading apparatus side, it is only necessary to determine which block's illuminated image information is effective for one line of image information divided into eight blocks. Therefore, it is appropriate to mask unnecessary image information on the image reading apparatus 2 side.

  FIG. 12 is a diagram illustrating an example of a mask circuit of the image reading apparatus 2 according to the third embodiment of the present invention.

  In FIG. 12, 8-bit digital image signals finally subjected to the image processing such as shading correction from the image reading device 2 are denoted as VD0 to VD7. Digital image signals PVD0 to PVD7 to be sent to the printer are generated from the image signals VD0 to VD7 via an 8-stage AND gate 1301. A mask signal MSK is connected to the other input terminal of the AND gate 1301, and the control circuit board 701 controls to input 1 while sending an effective image signal and to input 0 while sending an invalid image signal. .

Scale of the mask circuit shown in FIG. 12, an A ND gate 8 and one register (not shown) about, which is configured to ASIC702, also cost adding circuit of the order of magnitude Does not affect much.

  FIG. 11C shows an image received by the printer when the circuit shown in FIG. 12 is controlled.

  Here, the 8-bit digital image signal handles FFh as a black signal and 00h as a white signal. When the 8-bit digital signal is 00h is a black signal and FFh is a white signal, all the AND gates in FIG. 12 are replaced with OR gates. Further, it may be controlled to input 0 to the mask signal MSK while sending the effective image signal and to input 1 to the mask signal MSK while sending the invalid image signal.

  In FIG. 11C, the invalid image range is not reproduced on the printer side, and only the valid image range is reproduced.

  By the way, in this embodiment, since the image reading range is reduced, it is necessary to notify the user who performs image reading of the document reference position where the document is placed.

  FIG. 13 is a view of the platen glass 503 from the top according to the third embodiment of the present invention.

  In FIG. 13, the document table glass 503 includes a main scanning index 401, a sub scanning index 402, and a reference mark 403. The user places the original 504 on the original platen glass 503 with the original size marked on the index and the corner of the original placed on the reference mark 403. FIG. 13 shows a state in which an A4 size document 504 is placed according to an A4 index.

  Here, a case where the LED block 101b of the LED block group 101 stops lighting will be described with reference to FIG.

  FIG. 14 is a diagram showing the main scanning index in FIG.

  In FIG. 14, it is assumed that the main scanning index 401 is made of a member that transmits a certain amount of light. When the user starts reading a document image, the control circuit board 701 of the image reading apparatus 2 controls the reading unit to be disposed directly below the main scanning index 401 as shown in FIG.

  The control circuit board 701 controls the LED block 101c and the LEDs below the LED block 101c to light up. FIG. 14 shows that a broken line area that is not hatched emits light through the main scanning index 401. The LED block 101a and the LED block above it can be turned on, but are controlled to be turned off here.

  The user can recognize that an original can be read by placing the original in the range of the main scanning area 1501 emitting light through the main scanning index 401. Here, for example, the image is read by causing the LED block to emit light for 5 seconds, during which the user re-places the document and inputs the start of the reading operation again (for example, pressing the copy button). . If there is no re-input of the reading operation start within 5 seconds, the image reading apparatus 2 controls to turn off the LED block and interrupt the document reading operation.

  In addition, as in the first embodiment, the fact that a failure is occurring does not change, so that the user can recognize that a failure is occurring via the image reading device 2, a connected printer, an external device, or the like. It is desirable to encourage the user to respond.

  According to the third embodiment, a normal read image can be obtained even if a failure occurs in the drive circuit of the illumination light source. Even with a small size, a read image can be obtained without degrading the image quality.

1 is a cross-sectional view showing an internal configuration of an image copying apparatus equipped with an image reading apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a schematic configuration of an image reading apparatus 2 in FIG. 1. FIG. 3 is a diagram showing a part of the configuration of an LED substrate included in the document illumination lamp 501 in FIG. 2. FIG. 3 is a diagram illustrating an example of a control circuit of the image reading apparatus 2 in FIG. 2. 4A and 4B are diagrams illustrating a relative relationship between reading levels of the LED blocks 101a and 101b and the shading correction plate 511 in FIG. 3, in which FIG. 3A illustrates a normal time, and FIG. It is a figure which shows the structure of the LED board 200 at the time of the failure of the drive circuit 104b in FIG. It is a figure which shows the structure of the LED board 200 in the 2nd Embodiment of this invention. It is a figure which shows the structure of the LED board 200 in the 2nd Embodiment of this invention. It is a figure which shows the structure of the LED board 200 in the 2nd Embodiment of this invention. 6A and 6B are diagrams illustrating timing signals transmitted by an image reading apparatus according to a third embodiment of the present invention, where FIG. 5A illustrates a normal time, and FIG. 5B illustrates a time when a drive circuit 104b fails. FIG. 10 is a diagram illustrating an image sent from the image reading apparatus to the printer according to the third embodiment of the present invention, where (a) illustrates a normal time, (b) illustrates a timing signal after change, and (c) illustrates It shows after execution of mask processing. It is a figure which shows an example of the mask circuit of the image reading apparatus 2 in the 3rd Embodiment of this invention. It is the figure which looked at the platen glass 503 in the 3rd Embodiment of this invention from the upper part. It is a figure which shows the main scanning parameter | index in FIG. It is a figure which shows the structure of the conventional LED board. It is a figure which shows the structure of the conventional LED block.

Explanation of symbols

101a, 101b LED blocks 102a, 102b, 103a, 103b Changeover switches 104a, 104b Drive circuit 200 LED board 201 LED

Claims (5)

Have a plurality of illumination light sources are arranged linearly in the main scanning direction, illuminating means for illuminating an original,
One by one connected to each of the plurality of illumination sources, a plurality of driving circuit for lighting the connected light sources,
An image reading apparatus comprising: reading means for reading an image of the original from the original illuminated by the illumination means;
Detecting means for detecting a faulty driving circuit among the plurality of driving circuits;
Switching means for connecting an illumination light source connected to a malfunctioning drive circuit detected by the detection means among the illumination light sources to a malfunctioning drive circuit of the plurality of drive circuits ; An image reading apparatus comprising: 2. The image reading apparatus according to claim 1, wherein each of the plurality of drive circuits has a capability of supplying a current for turning on at least two of the plurality of illumination light sources. . The image reading apparatus according to claim 1, wherein one of the plurality of drive circuits has a capability of supplying a current for turning on all the plurality of illumination light sources of the illumination unit. And a display unit configured to display a message prompting a user to replace the drive circuit when the detection unit detects a faulty drive circuit from the plurality of drive circuits. Item 4. The image reading apparatus according to any one of Items 1 to 3.   The image reading apparatus according to claim 1, wherein the illumination light source includes a light source in which a plurality of LEDs are connected in series.

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