JP2002254703A - Exposure system and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure system which can precisely correct an exposure position and to provide an image forming device. SOLUTION: The distance gap between an even number chip and an odd number chip is roughly adjusted within a range of one resolution pitch by adjusting the output timing of an image data located in an odd number chip by one line, and transmission start timing and image data timing are controlled by a transfer clock for microscopic adjustment. More specifically, an output timing of a video signal outputted from a line buffer 50 by a line is adjusted through adjustment of a count value by counting of a line synchronization(L/S) signal inputted at a frequency of sub-scan direction resolution by a counter A48 and a rough adjustment by a line is carried out. The transfer start timing of a transfer thyristor 34 is decided by counting a clock 1 signal by the counter 46 and adjusting the count value, and microscopic adjustment by a transfer clock is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and an image forming apparatus, and more particularly, to a monochrome printer, an n-color printer, a full-color printer, or a film using an xerography technique for visualizing an image by exposure. The present invention relates to an exposure apparatus used for a film printer or the like that prints directly on paper or photographic paper, and an image forming apparatus for these.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus of this type has been proposed which includes an exposure device for performing exposure by using a light emitting array in which a plurality of light emitting diodes are arranged. For example,
In the technology described in Japanese Patent Application Laid-Open No. 8-216448, an exposure apparatus using a self-scanning LED array has been proposed.

According to Japanese Patent Application Laid-Open No. Hei 8-216448, in a self-scanning LED array, by arranging wiring terminal electrodes at the ends in the chip arrangement direction, the chip is made smaller (thinner) and higher resolution. .

In addition, an LED print head having a print width is formed by alternately arranging the chips in a staggered manner.
The arrangement interval of the staggered arrangement is an integral multiple of the emission point interval,
It is disclosed that linearization correction is performed in image data (dot units). The arrangement step is set to be within 0.2 mm.

That is, in Japanese Patent Application Laid-Open No. 8-216448, the resolution of the light emitting element can be realized up to about 1200 dpi. The distance from the light-emitting point to the outer shape of the element must be extremely short, and chipping of the light-emitting point at the end is likely to occur when a chip is cut out from the wafer, thereby lowering the yield. This problem is solved by providing a margin for the distance between the chip and the cutout surface of the chip and arranging the light emitting elements in a staggered manner in the arrangement direction. Also, Japanese Patent Application Laid-Open No.
In the technology described in Japanese Patent Application Publication No. 8 (1999) -1995, a staggered step is mounted at a position of an integral multiple of the resolution pitch in the main scanning direction, and furthermore, the image data output timing is adjusted in units of resolution lines to correct the image shift. ing.

Further, as disclosed in Japanese Patent Application Laid-Open No. 57-10162, adjacent light-emitting elements are alternately and complementarily arranged in n rows, and the distance between the diodes in the first row and the second row and the distance between the photoconductors. Exposure apparatuses and the like that perform exposure by delaying the light emission timing according to the speed have also been proposed.

[0007]

However, it is better that the step of arranging chips is as short as possible.
In the technique described in Japanese Patent Application Laid-Open No. 6448/2000, a step is widened due to the restriction of an integral multiple of the resolution, which may cause deterioration of image quality. For example, when the distance between the chip end and the light emitting point is 15 μm and the nominal value of the distance between adjacent chips is 5 μm, the nominal staggered step is 35 μm.
m, which is 1.7 times the pitch of the resolution of 1200 dpi = 21.17 μm, and it is not possible to correct the step by the correction in line units. Also, the bonding position is temporarily offset so that the distance between the chips is 12.3.
Even if the distance is increased to μm, the optical system using the selfoc lens has a large unevenness in the optical characteristics of the pitch of the rod lens diameter due to an increase in the step distance, which causes deterioration of an image.

In addition, since the positional accuracy error of the chip after bonding is about 2 μm to 5 μm due to mechanical accuracy, shrinkage of the adhesive for bonding the chip or the like at the time of curing, individual differences occur in the step distance. Then, as shown in FIG. 10B, the distance between the center of the lens and the light emitting point varies due to the accuracy of the bonding position of the chip, resulting in a step, so that an error in the accuracy of bonding the chip to the substrate is not allowed. That is, a slight shift occurs for each chip due to various factors such as an error generated in a bonding apparatus when bonding the chips, and an error in a distance between a center of gravity of light emission and a marker indicating the chip position. It is actually difficult to make it an integral multiple of the light emitting point interval.
There is a problem.

In the technique described in Japanese Patent Application Laid-Open No. Sho 59-10162, a delay circuit and a delay buffer are required for each dot, and the circuit configuration becomes very large, which is difficult to realize.

The present invention has been made to solve the above problems, and has as its object to provide an exposure apparatus and an image forming apparatus capable of correcting an exposure position with high accuracy.

[0011]

According to a first aspect of the present invention, there is provided an image processing apparatus, comprising: a plurality of light-emitting portions;
A light-emitting array in which the light-emitting unit sequentially emits light by sequentially transmitting a transfer clock for causing the light-emitting unit to emit light to the plurality of light-emitting units, wherein the light-emitting unit emits light in accordance with exposure data for performing exposure on a medium to be exposed. Light up the array,
An exposure apparatus for generating an exposure image on the medium to be exposed by moving the medium to be exposed in a direction substantially perpendicular to the arrangement direction of the light emitting units, wherein the exposure image is n times (n is 1) the cycle of the transfer clock. It is characterized by comprising a correction means for correcting the transfer start timing of the transfer clock in units of the above integer).

According to the first aspect of the present invention, the plurality of light emitting units of the light emitting array emit light sequentially by the transfer clock, and the medium to be exposed is moved in a direction substantially orthogonal to the arrangement direction of the light emitting units. An exposure image is generated. That is, the main scanning is performed by the light emission of the plurality of light emitting units of the light emitting array, and the sub scanning is performed by moving the medium to be exposed in a direction substantially orthogonal to the arrangement direction of the light emitting units.

Further, since the correction means corrects the transfer start timing of the transfer clock in units of n times the cycle of the transfer clock, the light emission timing of the light emitting unit can be adjusted in units of n times the transfer clock. That is, it is possible to adjust the line pitch in the sub-scanning direction by adjusting the start timing of the transfer clock to be transferred to the light emitting unit when performing main scanning of the subsequent line after one line main scanning is completed. Become.

Accordingly, the correcting means corrects the transfer start timing of the transfer clock in units of n times the cycle of the transfer clock, so that the exposure position can be adjusted with high precision.

According to a second aspect of the present invention, in the first aspect of the present invention, a plurality of the light emitting arrays are alternately arranged in a direction substantially orthogonal to an arrangement direction of the light emitting sections, and the light emitting arrays are arranged between the light emitting arrays. It is characterized in that the correction by the correction means is performed according to the step of the joint.

According to the invention described in claim 2, according to claim 1
In the invention described in (1), a plurality of light emitting arrays are alternately shifted in a direction substantially orthogonal to the arrangement direction of the light emitting units. That is, the light emitting arrays are arranged in a staggered manner as in the prior art. At this time, by arranging the light emitting arrays in a staggered manner, there may be a step at the joint between the adjacent light emitting arrays. However, according to the step at the joint between the light emitting arrays, the correcting means causes the light emitting section to emit light. By correcting the clock transfer start timing, highly accurate step correction can be performed in units of the transfer clock.

According to a third aspect of the present invention, in the first or second aspect, the adjustment is made such that the output timing of the exposure data is adjusted in resolution units in a direction substantially orthogonal to the arrangement direction of the light emitting units. It is characterized by further comprising means.

According to the third aspect of the present invention, the apparatus further comprises an adjusting means for adjusting the output timing of the exposure data in resolution units in a direction substantially orthogonal to the arrangement direction of the light emitting units. The line pitch can be adjusted. Therefore, by performing the coarse adjustment by the adjusting unit and then performing the fine adjustment by the correcting unit, the exposure position can be corrected with high accuracy.

According to a fourth aspect of the present invention, the exposure image is visualized by a visualization means for visualizing the exposure image a plurality of times to superimpose the images, or the visualization means is provided with a plurality of the visualization means and visualized by each visualization means. Image forming apparatus for forming an image by superimposing the images
An exposure apparatus according to claim 1 is provided, wherein the correction unit corrects a shift at the time of superimposing the images.

According to the fourth aspect of the present invention, an image forming apparatus which forms an image by superimposing images by performing visualization of an exposure image by a visualizing means a plurality of times, or visualizing an image by a plurality of visualizing means. An image forming apparatus that forms an image by superimposing images that have been overlapped with each other is provided with the exposure device according to claim 1, and a correction unit corrects a deviation of each color based on a deviation amount when the images of each color are superimposed. As a result, it is possible to superimpose images with high accuracy. For example, by providing the color image forming apparatus with a correction unit, it is possible to correct the color shift with high accuracy by the correction unit.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 is a diagram showing image formation to which the exposure apparatus according to the present embodiment is applied.

The image forming apparatus 12, as shown in FIG.
A charger 16, an exposure device 10, a developing device 18, a transfer device 20, and a static eliminator 22 are provided in this order along the rotation direction of the photoconductor drum 14, and the surface of the photoconductor drum 14 is
The charged photosensitive drum 14 is exposed based on image data charged to the exposure device 10 and is developed by the developing device 18, whereby an image is carried on the photosensitive drum 14. Then, the image carried on the photosensitive drum 14 is transferred onto a transfer medium 24 or a paper provided on the transfer medium 24 by a transfer unit 20 provided in contact with the photosensitive drum 14. Further, the transferred image is heated by a fixing device 26 provided on the downstream side in the transport direction of the transfer medium 24, and the image is fixed on the transfer medium or paper. Further, the charge is removed by the charge remover 22 on the downstream side in the rotation direction of the photosensitive drum 14, and the cleaning is performed by the cleaner 28.

Exposure apparatus 10 according to an embodiment of the present invention
Is used as an optical print head of such an image forming apparatus. FIGS. 1 and 4 are circuit block diagrams of an exposure apparatus 10 according to an embodiment of the present invention. The exposure apparatus 10 according to the present embodiment is disclosed in
Similarly to the technology described in Japanese Patent No. 16448, the light emitting chip 3
0 are alternately arranged (in a staggered pattern) (see FIG. 3).
Each light emitting chip 30 has a plurality of light emitting elements 32 arranged linearly and includes a transfer thyristor 34 (self-scanning LED array). As shown in FIGS. 10A and 10B, Selfoc (registered trademark) manufactured by Nippon Sheet Glass Co., Ltd. is provided above the light emitting chip 30.
A lens is located. Note that the light emitting chip 30 corresponds to the light emitting array of the present invention.

Also, as shown in FIG.
The distance from the end of the light emitting chip 30 to the center of light emission is represented by y1,
The distance y2 in the sub-scanning direction of the light emitting chip 30 is set. The distance y2 of the light emitting chip 30 in the sub-scanning direction is set such that the distance between the end of the light emitting chip 30 and the light emitting point is as short as possible regardless of the resolution. The distance is set to a minimum distance (2 to 10 μm) at which the members 30 do not contact each other. In the present embodiment, y1 = 15 μm and y2 = 5 μm.

Further, as shown in FIG. 3, the light emitting chips 30 in this embodiment are odd-numbered light emitting chips 30.
A and the even-numbered light emitting chips 30B are mounted so as to scan alternately in the opposite direction.

The exposure apparatus 10 according to the present embodiment comprises an odd-numbered light emitting chip 30A and an even-numbered light emitting chip 30b.
, And the even-numbered light emitting chips 30B have the same circuit configuration as the technology described in Japanese Patent Application Laid-Open No. 8-216448. That is, as shown in FIG. 4, a plurality of light emitting elements 32 whose cathode side is grounded are arranged, the anode of each light emitting element 32 is connected to the buffer 36, and the cathode side is grounded to the anode gate of the light emitting element 32. The anode gate of the transfer thyristor 34 and the resistor R are connected. The power supply V is connected to the other end of the resistor R, and the anodes of the transfer thyristor 34 are connected to the phase correction circuit 38, respectively. The transfer thyristor 34 connected to the phase correction circuit 38
Are divided into two series. The anode of the transfer thyristor 34 is connected to the cathode of the diode D, and the anode of the diode D is connected to the anode gate of the adjacent thyristor 34. That is, as shown in FIG. 4, adjacent diodes D are connected in series. Further, the cathode of the diode D at the last end is connected to the counter 40.

The phase correction circuit 38 converts the clock signal output from the video clock generation circuit 42 into two series of different clocks φ 1 and φ 2, and inputs the clocks to the transfer thyristor 34 of the light emitting chip 30 B and sends the clock to each light emitting element 32. To perform the transfer operation.

The counter 40 counts the line synchronizing signal (L / S) inputted at the cycle of the resolution in the sub-scanning direction (the cycle of the horizontal synchronizing signal φs), and outputs the image data from the buffer 36 based on the count value. Adjust the timing.

The buffer 36 holds a plurality of lines of the video signal, and outputs the video signal line by line according to the output signal of the counter 40.

On the other hand, as shown in FIG. 1, the circuit configuration of the odd-numbered light emitting chips 30A includes a plurality of light emitting elements 32 whose cathodes are grounded, and the anode of each light emitting element 32 is a FIFO (First In First Out). ) 44, the anode gate of the light emitting element 32 is connected to the anode gate of the transfer thyristor 34 whose cathode side is grounded and the resistor R. The power supply V is connected to the other end of the resistor R, and the anodes of the transfer thyristor 34 are connected to the phase correction circuit 38, respectively. The anode of the transfer thyristor 34 connected to the phase correction circuit 38 is 2
Are affiliated. The anode of the transfer thyristor 34 is connected to the cathode of the diode D, and the anode of the diode D is connected to the anode gate of the adjacent thyristor 34. That is, as shown in FIG. 1, adjacent diodes D are connected in series.
The cathode of the diode D at the last end is a counter B4
6 is connected.

The phase correction circuit 38, the counter B4
6 and the FIFO 44, the clock 1 signal is inputted, and the counter A and the counter B 46 are inputted with the line synchronization signal (L / S) signal. In the counter A48,
The line buffer 50 is connected, and the line buffer 50 is connected to the FIFO 44. The image data is input to the FIFO 44 via the line buffer 50. Further, a delay instruction (in clock units) is input to the counter B46, and a delay instruction (in line units) is input to the line buffer 50.

The phase correction circuit 38 converts the clock 1 (frequency is n times the transfer clock frequency, n is an integer of 1 or more) signal into two series of clocks φ1 and φ2 having different phases,
The data is input to the transfer thyristor 34 of the light emitting chip 30A to cause each light emitting element 32 to perform a transfer operation.

The counter A48 corresponds to the adjusting means of the present invention, and counts a line synchronizing signal (L / S) input at a period of the sub-scanning direction resolution (a period of the horizontal synchronizing signal φs) and adjusts the count value. By doing so, the video signal output timing is adjusted for each line.

The counter B46 corresponds to the correction means of the present invention, counts the clock 1 signal, adjusts the count value, determines the transfer start timing of the transfer thyristor 34, and provides a high-precision printing position in the sub-scanning direction. Make fine adjustments.

The line buffer 50 holds a plurality of lines of video signals, and adjusts the timing set for each line by the output signal of the counter B46. With this function, the print position in the sub-scanning direction is roughly adjusted efficiently with a small amount of memory even if there is a large step.

The FIFO 44 holds image data for one or two lines, and synchronizes with the clock 1 to generate a counter A4.
The signal is converted into a signal Sin that causes the exposure unit (light emitting element 32) to emit light in accordance with the timing adjustment value set in step 8, ie, the transfer start time of the transfer thyristor 34.

Next, a description will be given of a method of adjusting a step in the sub-scanning direction in the exposure apparatus 10 configured as described above.

FIG. 9 shows that the light emitting points are sequentially emitted from right to left (odd-numbered light emitting chip 30A) or left to right (even-numbered light emitting chip 30B) as described above.
The operation of moving the medium to be scanned in the sub-scanning direction by one resolution (in this case, it is 1200 dpi, 21.17 μm) during the period from the start to the end of the transfer of 56 dots is repeated three times. In the present embodiment, as described above, the distance between the end of the light emitting chip 30 and the light emitting point is set to 15 μm, and the nominal value of the distance between the adjacent light emitting chips 30 is set to 5 μm. 35 μm (15 μm
m × 2 + 5 μm), and the resolution is 1.7 times the pitch of 1200 dpi = pitch 21.17 μm.
If the correction is performed on a line-by-line basis according to the technique described in JP-A-8-216448, the level difference cannot be corrected. In order to eliminate the step, the bonding position is offset and the distance between the light emitting chips 30 is reduced by about one.
Since 2.3 μm (≒ 42.34 μm−15 μm × 2), that is, the line pitch is 21.17 μ, the step is eliminated by adjusting the distance between the light emitting chips 30 to 42.34 μm in two lines. However, the light emitting chip 30
Since the distance between them becomes longer, in an optical system using a selfoc lens, the optical characteristic unevenness of the pitch of the rod lens diameter becomes large, which causes deterioration of an image. In addition, since the positional accuracy error of the light emitting chip 30 after bonding occurs about 2 to 5 μm due to mechanical accuracy, shrinkage of the adhesive for bonding the light emitting chip 30 or the like during curing, individual differences occur in the step distance.

Therefore, in the exposure apparatus 10 according to the embodiment of the present invention, the output timing of the image data located on the odd-numbered light emitting chips 30A is adjusted on a line-by-line basis so that the even-numbered light-emitting chips 30A as shown in FIG. Th light emitting chip 30B
Is roughly adjusted within the range of one resolution pitch, and fine adjustment is performed by controlling the transfer start timing and the image data timing with the accuracy of the transfer clock unit.
That is, the counter A48 counts the line synchronizing signal (L / S) input in the cycle of the sub-scanning direction resolution, and adjusts the count value to thereby change the video signal output from the line buffer 50 line by line. The output timing is adjusted, and coarse adjustment is performed for each line.
Then, by counting the clock 1 signal by the counter B46 and adjusting the count value, the transfer start timing of the transfer thyristor 34 is determined, and fine adjustment is performed in units of the transfer clock. FIG. 6 shows an example of the transfer start timing when the image position is moved in the sub-scanning direction by two clocks, that is, 0.16 μm.

Thus, the steps of the light emitting chips 30 arranged in a staggered manner can be corrected with high accuracy while maintaining the good optical characteristics.
Image unevenness due to the staggered arrangement of 0 is eliminated, and high image quality can be achieved. Further, since the step can be adjusted only by adjusting the output timing of the video signal and the transfer start timing of the transfer thyristor, the step of the light emitting chips 30 arranged in a staggered manner can be corrected by a simple method. Further, by correcting the step of the light emitting chip 30 by combining the coarse adjustment and the fine adjustment, it is possible to perform the correction at high speed with a small amount of memory for the correction value.

In the present embodiment, since the distance between the steps of the light-emitting chips 30 arranged in a staggered manner is 35 μm as described above, the image data input to the odd-numbered light-emitting chips 30A has a timing corresponding to two lines. Set in the direction of delay, and then 7.34 μm (≒ 21.17 (1 resolution)
μm × 2−35 (step distance) μm), that is, (7.
34 / 21.17) × 256 ≒ 88 By leading the data output by the transfer clock, the writing step by the light emitting chips 30 arranged in a staggered manner can be corrected with an accuracy of 0.1 μm or less. More specifically, when the resolution in the sub-scanning direction is 1200 dpi (the moving amount of the medium to be exposed in one resolution unit is 21.17 μm), and the number of light emitting points (the number of LEDs) in one light emitting chip 30 is 256. , By controlling in units of transfer clocks,
Fine adjustment can be performed in increments of 1.17 / 256 ≒ 0.08 μm, and image streak defects at element joints can be eliminated.

At this time, the step of the light emitting chip 30 can be minimized irrespective of the resolution in the sub-scanning direction, so that light is emitted by using an area near the center of the optical system such as a lens (such as a selfoc lens). Can be transmitted, and variations in the amount of light and irregularities in the beam shape can be minimized, and image unevenness does not occur.

Further, the exposure apparatus 10 according to the present embodiment
Then, even if there is an error in bonding accuracy, a step distance caused by a manufacturing error of the light emitting chip 30, or an individual difference for each light emitting chip 30, the output timing of the video signal and the transfer thyristor according to the difference. By adjusting the transfer start timing, each error as described above can be corrected. For example, the position error of the light emitting element 32 in the sub-scanning direction may be 1 to 5 times smaller than the target value between the light emitting chips 30 close to each other due to the limit of the bonding accuracy of the light emitting chip 30.
It shifts by about μm. In addition, when the optical width and the mechanical error are included, even when the exposure width is about 350 μm or less, 10 to 1
Although about 00 μm is generated, in the present embodiment, the exposure position can be adjusted without increasing the accuracy of the bonding apparatus or the mechanism.

Although the light transfer direction can be adjusted in the sub-scanning direction by mounting the odd-numbered light-emitting chips 30A and the even-numbered light-emitting chips 30B in the same direction, the position adjustment in the sub-scanning direction is possible. Even if the timing is adjusted in this manner, as shown in FIG. 7, discontinuity occurs at the joint of the light emitting chips 30 at the resolution pitch in the sub-scanning direction. However, in the present embodiment, since the light emitting chips 30 are mounted so that the odd-numbered light emitting chips 30 and the even-numbered light emitting chips 30 alternately scan in the opposite directions, a continuous image can be obtained, and image defects can be obtained. Can be made inconspicuous.

As a method of measuring the step error and holding the adjustment amount, the step of measuring and inspecting the exposure apparatus 10 measures the exposure position step using a CCD or the like, and the correction amount is stored in the RAM on the drive circuit. May be written on the image forming apparatus, or after a visible image is actually formed on the image forming apparatus (in the case of xerography, a toner image formed on a photoreceptor or a fixed image formed on paper), a step in an image position is formed. May be measured and the correction amount may be stored. In the former case, the position can be measured with very high accuracy. On the other hand, in the latter case, if there is a mechanical angle error when mounting the image on the image forming apparatus, the correction is made including the deviation of the staggered step on the exposure surface when the photoconductor is cylindrical. This is particularly effective when the diameter of the photoconductor is reduced as a means for reducing the size and cost of the machine. Furthermore, in the latter case,
It is also possible to prepare an image position detection sensor in the image forming apparatus or a scanner for reading an output image, measure the level difference just before the machine enters the image forming operation, and read the measured level into the memory.

As a method of actually detecting the light emitting point position, all the dots or a plurality of light are emitted at a constant interval, and the average value of the positions in the sub-scanning direction is calculated.
The step distance is obtained after obtaining the position of 0, or the representative value of the position of each light emitting chip 30 is measured by selecting and measuring one representative point for each light emitting chip 30, and the step distance is obtained.
A two-dimensional CCD camera is installed at the joint between the light-emitting chips 30, and the light-emitting point at the transfer start and the light-emitting point at the transfer end are simultaneously incident to directly measure the level difference between adjacent light-emitting points. This can be realized by the following method.

In the above embodiment, the coarse adjustment and the fine adjustment are performed for the odd-numbered light-emitting chips 30A. However, not only the odd-numbered light-emitting chips 30A but also the even-numbered light-emitting chips 30B are used. You may make it the structure which performs a coarse adjustment and a fine adjustment. By doing so, exposure caused by mechanical distortion of components shared by the even-numbered light-emitting chip and the odd-numbered light-emitting chip 30, such as the optical system (lens), the substrate on which the light-emitting chip is mounted, and the holding member. The distortion of the exposure line over the entire width is obtained by adding the distortion correction amount in the sub-scanning direction at each scanning position to the odd-numbered light emitting chips 30A and the above-described step correction amount for the odd-numbered light emitting chips 30A. In addition, by correcting the amount of distortion at each position in the main scanning direction, the correction can be performed with high accuracy.

In the above-described embodiment, the example in which the present invention is applied to the image forming apparatus using one photosensitive drum 14 has been described. However, as shown in FIG. The present invention may be applied to an existing color image forming apparatus. That is, a plurality of photosensitive drums 14 (two shown in FIG. 8, but four photosensitive drums 14 for C (cyan), M (magenta), Y (yellow), and K (black) are provided. The charger 16, the exposure device 10, the developing device 18, the transfer device 20, the static eliminator 22, and the cleaner 28 are provided in this order along the rotation direction of each photosensitive drum 14. Drum 14
Is charged by the charger 16, and the charged photosensitive drum 14 is exposed and developed by the developing device 18 based on the image data input to the exposure device 10.
At this time, C, M, Y,
K toner images are formed on the photosensitive drum 14. Then, the toner images formed on the surfaces of the respective photoconductor drums 14 are sequentially transferred to a transfer medium or paper provided on the transfer medium by a transfer unit 20 provided in contact with the respective photoconductor drums 14. And a color image is formed by superimposing the four toner images. In such an image forming apparatus, even if the amount, position, direction, and the like of the distortion of each exposure device are different for each color, the correction value for the color shift amount is used instead of the correction value for the distortion amount described above. 8
As shown in (1), color shift can be corrected with high accuracy. For example, a color shift is detected by the color shift detection sensor 52, and based on the detection result, the exposure position is corrected in line units as described above, and the exposure position is corrected in transfer clock units transferred to the light emitting chip 30. This makes it possible to correct color misregistration with high accuracy.

Further, another type of color image forming apparatus,
For example, one photoconductor drum is developed with the first color during the first rotation and is transferred to a transfer medium (paper or an intermediate transfer body), and is developed with the second color during the second rotation, and is transferred to the transfer medium. (For example, in this case, Y
Even in a color image forming apparatus that forms a color image on a transfer medium by performing MCK four times), it is possible to eliminate a color shift in the sub-scanning direction between processes of each color by offsetting a correction value for each process. it can. further,
In the same manner, even in a color image forming apparatus that has an exposure and development process of a plurality of colors for one photosensitive member and reproduces a plurality of colors in one cycle, the color shift in the sub-scanning direction is similarly performed. Can be corrected.

Although the above embodiment has been described using the self-scanning LED array, it is possible to correct the steps of the light emitting chips 30 arranged in a staggered manner even if the transfer section and the light emitting section are separated. Can be.

[0051]

As described above, according to the present invention, the line pitch in the sub-scanning direction is adjusted in units of the transfer clock by correcting the transfer start timing of the transfer clock in units of n times the period of the transfer clock. Therefore, there is an effect that the exposure position can be adjusted with high accuracy.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of an odd-numbered light emitting chip in an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration and an arrangement of a light emitting chip in the exposure apparatus according to the embodiment of the present invention.

FIG. 4 is a circuit block diagram of an even-numbered light emitting chip in the exposure apparatus according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating adjustment of a line pitch.

FIG. 6 is a timing chart illustrating an example of adjustment of transfer start timing.

FIG. 7 is a diagram illustrating a step according to a light emitting chip arrangement direction.

FIG. 8 is a diagram illustrating color misregistration correction when the present invention is applied to a color image forming apparatus.

FIG. 9 is a diagram for explaining a step at a joint of light emitting chips.

FIG. 10 is a diagram showing a variation in distance between a lens center and a light emitting point due to bonding position accuracy of a conventional light emitting chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Exposure apparatus 12 Image forming apparatus 30 Light emitting chip 32 Light emitting element 34 Transfer thyristor 46 Counter A 48 Counter B

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 1/23 103 (72) Inventor Ken Tsuchiya 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. Ebina Works F term (reference) 2C162 AE12 AE28 AF07 AF53 AF60 AF92 FA04 FA17 2H106 AA44 AB02 BA00 5C051 AA02 CA08 DA04 DB29 DE02 EA00 FA06 5C074 AA10 BB04 BB26 CC26 DD11 EE06 FF15 GG09 HH04

Claims (4)

[Claims] 1. A medium to be exposed, comprising: a light emitting array in which a plurality of light emitting units are arranged, and the light emitting units sequentially emit light by sequentially transmitting a transfer clock for causing the light emitting units to emit light to the plurality of light emitting units. The light-emitting array emits light in accordance with exposure data for performing exposure, and an exposure image is generated on the exposure target medium by moving the exposure target medium in a direction substantially orthogonal to the arrangement direction of the light-emitting units. An exposure apparatus, comprising: a correction unit that corrects a transfer start timing of the transfer clock in units of n times (n is an integer of 1 or more) a period of the transfer clock. 2. The light emitting array according to claim 1, wherein a plurality of the light emitting arrays are alternately shifted in a direction substantially orthogonal to an arrangement direction of the light emitting units, and correction is performed by the correction means according to a step between seams between the light emitting arrays. The exposure apparatus according to claim 1, wherein 3. The exposure apparatus according to claim 1, further comprising an adjustment unit configured to adjust an output timing of the exposure data in a resolution unit in a direction substantially orthogonal to an arrangement direction of the light emitting units. apparatus. 4. A method of visualizing the exposure image a plurality of times by a visualization means for visualizing the exposure image and superimposing the images, or a method including a plurality of the visualization means and superimposing the images visualized by the respective visualization means. An image forming apparatus for forming an image, comprising: the exposure device according to claim 1, wherein the correction unit corrects a shift when the images are superimposed.