JP2005148175A - Image forming apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, by which exposure can be continued even when photometric values of a light source measured before exposure are partially out of a predetermined range but the light source has no abnormality, and an image forming method. <P>SOLUTION: The image forming apparatus is equipped with: a photometric means to measure the light quantity of each channel of a multiple light source when a recording material is exposed and outputted by an exposure section having the multiple light source based on image data; and a means to estimate the cause of abnormality based on at least one factor in the position, number, emission color and photometric value of channels out of the predetermined range when the photometric value measured before exposure is out of a predetermined range. The apparatus selects to stop exposure by judging the abnormality as an error based on the estimated cause or to continue the exposure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image forming method including an exposure unit of a multi-light source.

  As an image forming apparatus that forms an image by exposing a silver salt color photosensitive material with a multi-light source, for example, there is an image forming apparatus that creates a color proof (calibration product) for confirming image data for creating an original printing plate. It is known. Such an image forming apparatus generates a plurality of light beams of a plurality of colors from light emitting elements such as different light emitting diodes and semiconductor lasers, combines them as one light beam, and irradiates the silver salt color photosensitive material. A color image is formed by changing the amount of light beam based on the image data and exposing the silver salt color photosensitive material.

In the image forming apparatus including the multi-light source exposure unit as described above, the light amount of each channel of the multi-light source is measured and the light amount is corrected before exposure. When a channel whose photometric value is outside the specified range exists in a part of the light source, it is determined as an error and the exposure is stopped. However, the cause of the photometric value being out of the specified range is the abnormality of the light source and the abnormality of the photometry system. In the case of the abnormality of the photometry system, there is no problem with the light emission of the light source and exposure is possible. In addition, the image forming apparatus cannot be used, and the production efficiency of the apparatus is reduced.
JP 2000-43314 A

  The present invention has been made in view of the above-described problems of the prior art, and allows exposure to be continued if there is no abnormality in the light source even if a part of the photometric values measured before exposure are out of the specified range. An object is to provide an image forming apparatus and an image forming method.

  In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus that exposes and outputs a recording material by an exposure unit having a multi-light source based on image data, and the amount of light of each channel of the multi-light source. If the photometric value measured before exposure and the photometric value measured before exposure are out of the specified range, an abnormality is caused based on at least one of the position, number, emission color, and photometric value of the channel out of the specified range. And a means for estimating the cause of the above, and switching whether to stop exposure or to allow exposure to continue as an error based on the estimated cause.

  According to this image forming apparatus, even if a photometric value of a part of the light source measured before exposure is out of the specified range due to a photometric failure or a photometric means failure, the exposure is performed if the light source is not abnormal. Can continue. For this reason, since the use of the image forming apparatus can be continued until the photometric means or the like is repaired, the production efficiency of the apparatus is not lowered.

  In the image forming apparatus, the image forming apparatus further includes a warning unit, and when the exposure is switched to continue, the warning unit issues a warning to alert the user and allow the user to check the image. Even if the estimation is wrong, it is possible to prevent accidents due to image defects.

  In addition, when exposure is performed with the exposure being continued, a mark serving as a mark indicating that a photometric value abnormality has occurred, for example, at the end of the output recording material can be used without interrupting the output process. By paying particular attention to the images containing the mark, it is possible to prevent accidents due to image defects even if the cause of the abnormal photometric value is wrongly estimated.

  And a means for storing a table of light source driving values and photometric values for each channel, and a means for correcting the table based on the photometric values measured before exposure of the respective channels by the photometric means. It can be configured as follows.

  Further, when the exposure is continued, the table can be corrected by applying a correction value of a channel in which the photometric value is normal, the same color, and the position is close to a channel having an abnormal photometric value. In the case of continuous exposure, a correction value for a channel having the same color, a close position, and a normal photometric value can be applied to a channel having substantially the same temperature condition.

  Further, when a temperature measurement unit is provided in the optical unit that houses the multi-light source or the head unit of the multi-light source and the exposure is continued, a correction value is determined based on the temperature measurement value by the temperature measurement unit, and the table is stored. It can be corrected. In the case of continuous exposure, by determining the correction value based on the temperature measurement value by the temperature measurement means of the multi-light source, it is possible to correct the light amount fluctuation due to temperature regardless of the photometric value.

  An image forming method according to the present invention is an image forming method in which a recording material is exposed and output with a multi-light source based on image data, the step of measuring the light quantity of each channel of the multi-light source before the exposure, and the measurement If the measured photometric value is out of the specified range, estimating the cause of the abnormality based on at least one of the position, number, emission color, and photometric value of the channel out of the specified range; Switching based on whether the exposure is stopped or the exposure can be continued based on an error.

  According to this image forming method, exposure is performed when it is determined that there is no abnormality in the light source even if the photometric value of a part of the light source measured before exposure is out of the specified range due to a photometric failure or a photometric unit failure. Can continue. For this reason, since the use of the apparatus can be continued until the photometry unit or the like is repaired, the production efficiency of the apparatus does not decrease.

  In the image forming method, when the exposure is switched to allow continuation of exposure, it further includes a step of issuing a warning to alert the user and allow the user to check the image. If the cause estimation of the photometric value abnormality is wrong However, accidents caused by image defects can be prevented.

  In addition, when performing exposure with the exposure continued, a mark serving as a mark is added to the output recording material so that the output process is not interrupted and the image with the mark is checked with particular care. Thus, even if the cause estimation of the photometric value abnormality is wrong, an accident due to an image defect can be prevented.

  It is preferable that the method further includes a step of storing a table of light source driving values and photometric values of each channel, and a step of correcting the table based on photometric values measured before exposure of the respective channels.

  Further, when the exposure is continued, the table can be corrected by applying a correction value of a channel in which the photometric value is normal, the same color, and the position is close to a channel having an abnormal photometric value. In the case of continuous exposure, a correction value for a channel having the same color, a close position, and a normal photometric value can be applied to a channel having substantially the same temperature condition.

  Further, when the temperature of the optical unit accommodating the multi-light source or the head unit of the multi-light source is measured and the exposure is continued, the correction value can be determined based on the temperature measurement value and the table can be corrected. . In the case of continuous exposure, by determining the correction value based on the temperature measurement value by the temperature measurement means of the multi-light source, it is possible to correct the light amount fluctuation due to temperature regardless of the photometric value.

  According to the image forming apparatus and the image forming method of the present invention, the exposure can be continued if there is no abnormality in the light source even if the photometric values of a part of the light source measured before the exposure are out of the specified range. For this reason, the production efficiency of the apparatus does not decrease.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the appearance of the entire image forming apparatus according to the present embodiment. FIG. 2 is a view of the inside of the image forming apparatus of FIG. 1 as viewed from the front side. FIG. 3 is a plan view of the main part of the drum and the optical unit of the image forming apparatus shown in FIG. 2 as viewed from above.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 according to the present embodiment creates a color proof (calibration sample) for confirming a pattern, color tone, sentence, character, etc. to be printed out. An exposure unit 11 that exposes a silver salt color photosensitive material (hereinafter also simply referred to as “photosensitive paper”) to form an image and a developing unit 21 that develops the exposed photosensitive paper are provided.

  The exposure unit 11 includes a front panel 5 that can be opened and closed so that maintenance can be performed from the front side, a display unit 2 that includes various information displays and a touch panel and can be input for operation of the entire apparatus, and a roll-like silver salt color inside. Loading sections 12 and 12 ′ capable of loading a cartridge 13 containing photosensitive paper, which is a photosensitive material, after the paper feed covers 3 and 4 are opened. FIG. 1 shows a state before and after the cartridge 13 is loaded in the loading units 12 and 12 ′.

  The development unit 21 includes an upper panel 6 that can be opened and closed for maintenance, and a replenishment panel 7 that is provided on the front surface so as to be opened and closed for replenishment of a developing solution or the like.

  As shown in FIG. 2, the exposure unit 11 of the image forming apparatus 1 is loaded with loading units 12 and 12 for loading and storing a dedicated cartridge 13 that houses photosensitive paper, which is a sheet-like photosensitive material wound inside a roll. ', A feeding unit 14 including a pair of conveying rollers 40, 41, and 42 for feeding the photosensitive paper from the cartridge 13 loaded in the loading unit 12, 12', and the photosensitive paper fed from the feeding unit 14. A drum 10 that rotates in the rotation direction R for main scanning while vacuum-sucking and holding S on the outer peripheral surface, and an optical unit 16 that exposes a photosensitive paper on the drum 10 to light beams such as LED light and laser light. A sub-scanning unit 17 that transports the optical unit 16 in the sub-scanning direction (vertical direction in FIG. 1) H (FIG. 3) for sub-scanning, and a peeling member that peels off the photosensitive paper on the drum 10 after image recording 15. The exposed photosensitive paper is conveyed to the developing unit 21 through the outlet 19 and the connecting portion 19a.

  The image forming apparatus 1 shown in FIG. 2 further includes a driven roller 31 that is arranged on the downstream side of the conveying roller pair 42 and is driven to rotate following the conveyance of the photosensitive paper fed toward the drum 10, and the photosensitive paper between the drum 10. The driven roller 31 to be conveyed, the accumulating guide member 18 for guiding the photosensitive paper when the photosensitive paper peeled off from the drum 10 by the peeling member 15 is conveyed by the drum 10 and the driven roller 31, and the accumulating guide member 18 A conveying roller pair 32 that further conveys the photosensitive paper that has been conveyed to the outlet 19 and an accumulator formed by opening a part of the accumulating guide member 18 to accumulate the photosensitive paper that has reached the conveying roller pair 32. The rate unit 30 and a detection sensor 33 that detects the leading edge of the photosensitive paper disposed in the vicinity of the downstream side of the conveyance roller pair 32 are provided.

  A relatively narrow driven roller 43 disposed in the vicinity of the downstream side of the conveying roller pair 42 is driven to rotate along with the movement of the recording paper, and a rotary encoder (not shown) is connected coaxially with the driven roller 43. . By rotating the rotary encoder together with the driven roller 43 and measuring the rotation amount, the length of the photosensitive paper wound around the rotary drum 10 through the pair of conveying rollers 42 can be obtained. The downstream conveying roller pair 32 has a one-way clutch structure and can freely rotate in the direction of feeding the photosensitive paper downstream.

  A cut portion 10a for cutting the photosensitive paper is disposed in the vicinity of the downstream side of the pair of conveyance rollers 40 and 41 in FIG. 2, and each cut portion 10a has a rotary cutter that is rotationally driven by a motor (not shown). The photosensitive paper is cut into a predetermined length based on the above-described measurement of the length of the photosensitive paper.

  The developing unit 21 in FIG. 2 performs wet development on the exposed photosensitive paper sent from the exposure unit 11, and includes a developing unit 23 that performs development processing of the photosensitive paper, a fixing unit 24 that performs fixing processing, and a stable unit. A stabilization unit 25 that performs processing, a drying unit 26 that performs drying processing, and a discharge unit 27 that discharges the dried photosensitive paper to the outside by a pair of conveyance rollers 27a and the like.

  As shown in FIG. 3, in the drum 10 of the image forming apparatus 1, the rotation shaft 14a of the rotation shaft portion 14 ′ and the rotation shaft 15a of the rotation shaft portion 18a are rotatable to the support bases 34a and 34b via the bearings 33a and 33b. It is pivotally supported. One rotating shaft 15a of the drum 10 is provided with a driving pulley 35a, which is connected to an output pulley 35b of a drum driving pulse motor M6 by a belt 36 and driven by the drum driving pulse motor M6. 10 rotates. The rotary shaft 15a of the drum 10 is provided with a rotary encoder 37, which outputs a pulse signal for rotation and is used for pixel clock control synchronized with the rotation of the drum.

  The other rotating shaft 14a of the drum 10 is connected to the suction blower P1. A large number of suction holes 31c are formed on the surface of the drum 10 so as to extend linearly in the direction of the rotation axis. The inside of the drum 10 is depressurized by driving the suction blower P1, and the photosensitive paper is sucked onto the surface of the drum 10. .

  The optical unit 16 is configured to be movable in parallel with the drum axis by the sub-scanning unit 17, and performs image writing by exposing the photosensitive paper adsorbed to the drum 10 with a light beam. As shown in FIG. 3, the optical unit 16 includes an LED unit 320, an LED unit 321, and an LED unit 322 as multi-light sources having different three wavelengths.

  Each LED unit 320, 321, 322 includes a light emitting diode (LED) disposed on a substrate for 32 channels, and the light beam from each LED unit 320, 321, 322 passes through mirrors 325, 326, 327. Thus, the image is exposed from the condenser lens 331 onto the photosensitive paper on the drum 10. The exposure shutter 332 is opened / closed by an exposure solenoid 333 to open / close the optical path at the start / end of exposure. A temperature sensor 60 is disposed in the vicinity of each LED unit 320, 321, 322.

  The plurality of LED units 320, 321, and 322 are configured to emit light of, for example, B (blue) having a wavelength of about 450 nm, G (green) having a wavelength of about 540 nm, and R (red) having a wavelength of about 650 nm. When a silver salt color photosensitive material is exposed by each LED unit, Y (yellow) is developed by B, M (magenta) is produced by R, and C (cyan) is produced by G.

  The optical unit 16 is fixed to a moving belt 340 and guided by a pair of guide rails 341 and 342 so as to be movable in the sub-scanning direction H parallel to the drum axis and in the opposite direction H ′. The moving belt 340 is stretched over a pair of pulleys 343 and 344. One pulley 344 is connected to the output shaft 345 of the sub-scanning motor M7, and the optical unit 16 is sub-scanned in parallel with the drum axis by driving the sub-scanning motor M7. Move in the direction H and in the opposite direction H ′.

  Further, as shown in FIG. 3, a photometric unit 57 composed of a light receiving element such as a photodiode is disposed at an extended position parallel to the drum axis of the outer peripheral surface of the rotary drum 10, and the position of the home position in FIG. The optical unit 16 moves slightly in the direction H ′, and the light beams from the LED units 320 to 322 enter the photometry unit 57, whereby the light amount of the light beam of each LED of each channel can be measured.

  As shown in FIG. 3, the suction blower P <b> 1 sucks the inside of the drum 10 through the suction connection pipe 51 by an air suction pump, and sets the inside of the drum 10 to a negative pressure before the exposure unit 11 starts the exposure, thereby adsorbing the photosensitive paper to the outer peripheral surface. .

  Next, the LED units 320 to 322 and the photometry unit 57 will be further described with reference to FIGS. FIG. 4 is a plan view showing a state in which light beams from light sources for 32 channels constituted by the plurality of LED units 320 to 322 in FIG. 3 are arranged. FIG. 5 is a plan view showing a state where spots of light beams from the 32-channel light source in FIG. 4 are arranged on the light receiving surface of the photometry unit.

  When a light beam is emitted from the LED for 32 channels from the condenser lens 331 in FIG. 3, the plurality of LED units 320 to 322 has 32 channels from the left end channel 59a to the right end channel 59e as shown in FIG. The light beam 59 simultaneously irradiates the photosensitive paper on the drum 10, and at this time, a plurality of light beams of B, G, and R having different wavelengths can be emitted from the channels 59a to 59e. As shown in FIG. 4, the light source channels 59 a to 59 e are arranged substantially parallel to the sub-scanning direction H, but may be arranged to be inclined with respect to the sub-scanning direction H.

  When the optical unit 16 in FIG. 4 moves to a position where each light beam from the plurality of LED units 320 to 322 can irradiate the photometry unit 57, light of 32 channels enters the light receiving surface 58 of the photometry unit 57 as shown in FIG. A beam 59 is irradiated. By driving each LED of each LED unit 320 to 322 and emitting light sequentially from, for example, the leftmost channel 59a in FIG. 4, the light amount of the light beam of each channel 59a to 59e is measured, and based on this photometric value Abnormal channels can be detected.

  FIG. 6 shows a block diagram of a flow of image data in the exposure unit 11 of the image forming apparatus 1 of FIGS. 1 to 5 and a control system of the image forming apparatus 1.

  As shown in FIG. 4, the image forming apparatus 1 shown in FIGS. 1 to 3 creates halftone image data from raster data by an RIP (Raster Image Processor) 49, which is an external image processing apparatus, in order to create a color proof. The halftone image data is transferred from the RIP 49 to the exposure unit 11.

  As shown in FIG. 6, the exposure unit 11 temporarily stores the image data I / F unit 52 to which the halftone image data from the external RIP 49 is input and the halftone image data from the image data I / F unit 52. A data buffer 53 comprising a hard disk storage device to be output, a look-up table 54 for associating light source drive values for YMCK halftone dot image data from the data buffer 53 and providing exposure data for exposure on photosensitive paper; A plurality of D / A converters 55a, 55b, 55c corresponding to each of the B, G, R LED units 320 to 322 for converting the digital signal of the exposure data from the up table 54 into an analog signal, and the D / A converter Each LED of each LED unit 320-322 is directly analog-modulated by each analog signal from 55a-55c. Includes a plurality of drivers 56a to live, 56b, and 56c, the.

  6 includes a central processing unit (CPU) and the like, and receives signals from the photometry unit 57 and the temperature sensor 60, and receives an image data I / F unit 52, a data buffer 53, and a lookup table. 54, controlling the display unit 2 and other device parts.

  The light source drive value-photometric value table 61 in FIG. 6 is a table of photometric values for the light source drive values (0 to 4095) of the LEDs of the LED units 320 to 322. The control unit 50 sets the look-up table 54 for each exposure so as to associate the light source drive value with the YMCK binary halftone image data, but the light source drive value-photometric value table 61 determines the light source drive value. Will be described.

  (1) The light source drive value-photometric value table 61 is created at the time of device calibration before exposure, and is stored in the memory by the control unit 50.

  (2) Before each exposure, each LED of the LED units 320 to 322 is turned on with a fixed light source driving value, and a photometric value is obtained for each channel by the photometric unit 57 in FIGS.

  (3) The obtained photometric value is compared with the value in the light source drive value-photometric value table 61 to obtain a correction coefficient. Further, the correction coefficient may be determined based on the temperature sensor value from the temperature sensor 60.

  (4) After applying the correction coefficient to the desired exposure amount (light quantity value) of the CMYK image data, the corresponding light source drive value is obtained from the light source drive value-photometric value table 61 and set in the LUT 54. The above setting operation is performed for each channel.

  Further, before exposure, the control unit 50 determines the abnormality of the photometric value obtained for each channel by receiving the light beams from the respective channels 59a to 59e of FIG. 4 by the photometric unit 57 of FIG. .

  When L1 = light source driving value−photometric value in the photometric value table 61 and L2 = 200 (range fluctuating depending on temperature), the following expression (1) or (2) is satisfied, and the photometric value is out of the specified range. It is judged as abnormal.

Photometric value <(L1-L2) (1)
Photometric value> (L1 + L2) (2)

  Next, when the photometric value of the LED (light source) deviates from the specified range as described above and the channel is determined to be abnormal, it is an abnormality of the photometric system such as the photometric unit 57 or the abnormality of the LED (light source). The controller 50 estimates whether or not

  (1) When the photometric value of the same channel is abnormal in BGR, it is assumed that the photometric system is abnormal and the light source is normal, and the correction coefficient of the normal channel is used.

  (2) When all the B, G, or R channels are abnormal, the photometric system is abnormal and the light source is estimated to be normal, and a correction coefficient is obtained from the measured value of the temperature sensor 60.

  (3) Except for the above, it is determined that the LED (light source) of the channel is in error, and exposure is stopped.

  As described above, when the photometric value is abnormal and it is estimated that the photometric system is abnormal, the control unit 50 in FIG. 6 displays a warning on the display unit 2 and allows the exposure to be continued. Alternatively, when the exposure is continued, exposure is performed so that a mark serving as a mark is added to the edge of the image or the outside of the image.

  Next, the operation of the image forming apparatus 1 of FIGS. 1 to 6 will be described with reference to the flowchart of FIG.

  First, when halftone image data is input from the external RIP 49 (S01), the control unit 50 conveys the photosensitive paper from the loading unit 12 or 12 'toward the drum 10 by the conveyance roller pair 40 to 42 or the like (S02). Then, the photosensitive paper cut to a predetermined length by the cut portion 10a is wound around the drum 10 and the suction blower P1 is operated and held by suction.

  On the other hand, the optical unit 16 at the home position in FIG. 3 moves to the photometry unit 57, and the photometry unit 57 measures the light quantity of each of the channels 59a to 59e in FIG. 4 (S03). It is determined whether or not the photometric value is abnormal according to the above formula (1) or (2) (S04). If the photometric value is out of the specified range of the above formula (1) or (2), it is determined that the photometric value is abnormal. When it is determined that the photometric value is normal, a correction coefficient is obtained from the acquired photometric value and the light source drive value-photometric value table 61.

  If the photometric value of the same channel is abnormal in BGR (S05), the light source (LED) is estimated to be normal, the normal channel correction coefficient is set as the channel correction coefficient (S06), and a warning is displayed on the display unit 2. (S07).

  Next, when all the B, G, or R channels are abnormal (S08), it is estimated that the light source (LED) is normal, a correction coefficient is obtained from the measured value of the temperature sensor 60, and is used as the correction coefficient for those channels (S09). ), A warning is displayed on the display unit 2 (S10).

  Except that the light source (LED) is estimated to be normal in the above steps S05 and S08, the LED (light source) of the channel is abnormal and is determined to be an error, and the exposure is stopped (S11).

  The warning display in steps S07 and S10 alerts the user that the photometric value is abnormal, allows the user to check the image, and even if the cause of the photometric value abnormality is wrong, an accident caused by an image defect Can be prevented. Note that, as such warning means, for example, a blinking lamp or a buzzer that emits a warning sound may be provided.

  Next, after applying the correction coefficient obtained as described above to the desired exposure amount (light quantity value) of the CMYK image data, the corresponding light source drive value is obtained from the light source drive value-photometric value table 61 and stored in the LUT 54. Set (S12).

  Next, the optical unit 16 is sub-scanned in the sub-scanning direction H, and the drum 10 is rotated in the main scanning direction (rotation direction R), thereby exposing the photosensitive paper with the light beam from each LED of the optical unit 16 (S13). ).

  When the above exposure is completed, the photosensitive paper exposed by the exposure is peeled off from the drum 10 by the peeling member 15 and conveyed to the outlet 19 by the conveying roller pair 32 or the like (S14), sent to the developing unit 21 from the connection portion 19a, After developing the photosensitive paper (S15), it is output to the discharge unit 28 (S16).

  In the above-described image forming apparatus according to the present embodiment, the cause of the photometric value of each LED of the LED units 320 to 322 acquired before exposure being out of the specified range is as follows: (a) Abnormal light source, (b) Photometric unit 57, etc. (B) In the case of a photometric system abnormality, there is no problem with the light emission of the light source and exposure is possible, so the cause of the photometric value deviating from the specification is estimated. If it is estimated that the photometry system is abnormal, the exposure can be continued. Thereby, since the use of the image forming apparatus can be continued until the photometry unit or the like is repaired, the production efficiency of the apparatus is not lowered.

  When the photometric value of each LED is out of the specified range as in the above formulas (1) and (2), the cause can be estimated based on the position, number, emission color, and photometric value of the channel out of the specified range. .

  As described above, according to the present embodiment, even if the photometry unit 57 becomes abnormal or fails in photometry, the exposure can be continued if there is no abnormality in the light source. Can also use the device.

  In addition, since the light amount fluctuation of the light source is greatly affected by temperature, in the case of continuous exposure, by applying a correction value for a channel with the same color, close position, and normal photometric value, a channel with almost the same temperature condition The correction value can be applied.

  In the case of continuing exposure, the correction of the correction value based on the temperature sensor value from the temperature sensor 60 can correct the light amount fluctuation due to the temperature without using the photometric value.

  In the case of continuous exposure, instead of taking the warning display / confirmation procedure on the display unit 2, a mark indicating that a photometric abnormality has occurred is added to the image edge of the photosensitive paper, etc. In this case, the output process is not interrupted, and the marked image is checked with particular care, so that even if the cause of the light metering abnormality is wrongly estimated, an accident due to an image defect can be prevented.

  As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the technical idea of the present invention. For example, it is needless to say that the image forming apparatus according to the present invention can be applied to other than the creation of a color proof.

  Further, although the number of light source channels has been described as 32 channels, the present invention is not limited to this, and can be increased or decreased as appropriate, such as 16 channels, 64 channels, or 128 channels.

1 is a perspective view illustrating an appearance of an entire image forming apparatus according to an embodiment. FIG. 2 is a diagram of the inside of the image forming apparatus in FIG. 1 viewed from the front side. FIG. 3 is a plan view of a main part when a drum and an optical unit of the image forming apparatus of FIG. 2 are viewed from above. It is a top view which shows the state in which the light beam from the light source for 32 channels comprised by several LED unit 320-322 of FIG. 3 was located in a line. FIG. 5 is a plan view showing a state in which spots of a light beam from a 32-channel light source in FIG. 4 are arranged on a light receiving surface of a photometry unit. FIG. 4 is a diagram showing a flow of image data and a control system of the image forming apparatus 1 in the exposure unit 11 of the image forming apparatus 1 of FIGS. 7 is a flowchart for explaining an operation in the image forming apparatus 1 of FIGS. 1 to 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Display part (warning means)
10 ... Rotating drum 11 ... Exposure unit (exposure unit)
16 ... Optical unit 21 ... Development unit 50 ... Control unit 54 ... Look-up table (LUT)
57 .. Photometric part (photometric means)
59... 32 light beams 59a to 59e... Channel 60... Temperature sensor 61... Light source drive value-photometric value table 320, 321, 322.
S: photosensitive paper, silver salt color photosensitive material (recording material)

Claims (12)

An image forming apparatus that exposes and outputs a recording material by an exposure unit having a multi-light source based on image data,
Photometric means for measuring the light quantity of each channel of the multi-light source;
Means for estimating the cause of an abnormality based on at least one of the position, number, emission color, and photometric value of a channel outside the specified range when the photometric value measured before exposure is out of the specified range; With
An image forming apparatus that switches whether to stop exposure or to allow exposure to continue as an error based on the estimated cause. The image forming apparatus according to claim 1, further comprising a warning unit, wherein the warning unit issues a warning when the exposure is switched to continue. 3. The image forming apparatus according to claim 1, wherein a mark serving as a mark is added to the output recording material when the exposure is performed while the exposure is continued. 4. Means for storing a table of light source driving values and photometric values of each channel;
4. The image forming apparatus according to claim 1, further comprising means for correcting the table based on a photometric value measured before exposure of each channel by the photometric means. When the exposure is continued, the table is corrected by applying a correction value of a channel in which the photometric value is normal, the same color, and the position is close to a channel in which the photometric value is abnormal. 5. The image forming apparatus according to 4. When a temperature measurement unit is provided in the optical unit that houses the multi-light source or the head unit of the multi-light source and the exposure is continued, a correction value is determined based on the temperature measurement value by the temperature measurement unit, and the table is corrected. The image forming apparatus according to claim 4, wherein the image forming apparatus is an image forming apparatus. An image forming method for exposing and outputting a recording material with a multi-light source based on image data,
Measuring the light quantity of each channel of the multi-light source before the exposure;
When the measured photometric value is out of the specified range, estimating the cause of the abnormality based on at least one of the position, number, emission color, and photometric value of the channel out of the specified range;
Switching between whether to stop exposure or to allow exposure to continue as an error based on the estimated cause. The image forming method according to claim 7, further comprising a step of issuing a warning when the exposure is switched to continue. 9. The image forming method according to claim 7, wherein a mark serving as a mark is added to the output recording material when exposure is performed with the exposure continued. Storing a table of light source driving values and photometric values of each channel;
The image forming method according to claim 7, further comprising a step of correcting the table based on a photometric value measured before exposure of each channel. When the exposure is continued, the table is corrected by applying a correction value of a channel in which the photometric value is normal, the same color, and the position is close to a channel in which the photometric value is abnormal. The image forming method according to 10. When measuring the temperature of the optical unit accommodating the multi-light source or the head unit of the multi-light source and continuing the exposure, a correction value is determined based on the temperature measurement value and the table is corrected. The image forming method according to claim 10 or 11.

Images