JPH09265222A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce man-hours needed for adjustment by forming predetermined specific adjustment images onto corresponding photoreceptors, transferring the adjustment images formed on the photoreceptors to paper, reading the adjustment images transferred to the paper, and adjusting the timing of exposure to each photoreceptor based on the corresponding read adjustment image. SOLUTION: An adjustment-image writing control means 91 forms the predetermined adjustment images in an adjustment-image data storage part 82 onto the corresponding photoreceptors via a writing part 3. The photoreceptors transfer the adjustment images to paper. A scanner 1 reads the adjustment images transferred to the paper. An exposure-timing control means 9 adjusts the timing of exposure to each photoreceptor based on the corresponding adjustment image read by the scanner 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device for exposing a plurality of photoconductors to form monochromatic images of different colors on the photoconductors and transferring the monochromatic images formed on the photoconductors to a sheet in sequence. The present invention relates to a photographic device, particularly to prevention of color misregistration.

[0002]

2. Description of the Related Art Today, color copying has become popular in various industries such as the printing industry and the construction industry. In the case of color copying, since a plurality of single color images are superimposed to form one color image, it is necessary to accurately adjust the formation timing of each single color image.

As a method of adjusting the formation timing of each single color image, for example, a grid pattern in which each color forming the image is shifted by 40 mm is printed on the paper, and the interval between the lines is within a certain range based on the black line. Was manually adjusted so that

[0004]

However, the above-mentioned adjustment is a precise work, and requires skill and time.

The present invention has been made in order to eliminate such disadvantages, and an object thereof is to automatically adjust the image forming timing to reduce the adjustment man-hours.

[0006]

The electrophotographic apparatus according to the present invention forms a predetermined specific image on each photoconductor,
The image formed on each photoconductor is transferred to a paper, the image transferred to the paper is read, the exposure timing of each photoconductor is adjusted based on the read image, and the adjustment man-hour is reduced.

Further, in the vicinity of the exposure start position on the exposure start line and the vicinity of the exposure end position on the exposure end line of the first photoconductor located on the most upstream side when the sheet is conveyed, Near the exposure end position on the exposure start line,
Near the exposure start position on the exposure start line of the first photoconductor, near the start position on the exposure end line and near the exposure end position,
Alternatively, a reference image is formed on the exposure start line, near the exposure start position, near the exposure end position, near the exposure start position and near the exposure end position on the exposure end line of the first photoconductor, and then on the second and subsequent photoconductors. A reference image formed on the first photoconductor is used as a reference to form a comparative image having a positional relationship according to the arrangement of the photoconductors, and the image formed on each photoconductor is transferred to a sheet of paper. Read the transferred reference image and comparison image,
The exposure timing of the second and subsequent photoconductors is adjusted based on the difference between the read relative position of the reference image and the comparative image and the preset relative position of the reference image and the comparative image.

Further, as the adjustment value of the exposure timing of the photoconductor, a statistical value of the difference between the relative position between the actual reference image and the comparison image and the preset relative position between the reference image and the comparison image is obtained, Make the adjustment value of the exposure timing of the photosensitive member stable.

Further, when the obtained adjustment value exceeds a preset limit value, the user is notified of that fact, and the exposure of the photosensitive member in the poor adjustment state is prevented.

Further, the exposure timing is adjusted by changing the time from the input of the sync mark detection signal indicating the exposure start reference position to the exposure of the photoconductor and the exposure speed in the main operation direction of the image.

Further, after exposing the first photoconductor to the second photoconductor,
The exposure timing is adjusted by changing the time until the subsequent exposure of the photoconductor.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrophotographic apparatus of the present invention includes, for example, a digital electrophotographic copying machine, which exposes a plurality of photoconductors to form monochromatic images of different colors on each photoconductor. , A device for sequentially transferring a monochromatic image formed on each photoconductor to a sheet.

The electrophotographic apparatus has, for example, a scanner, an image processing section, a writing section, four transfer devices, a transfer belt, a fixing device, a belt cleaning device, an image memory and an adjusting section. The scanner irradiates a color document with light, and the reflected light is separated into three primary colors of light (green, blue, red) by a color CCD, and the image on the document is read. The image processing unit is based on image data of green (hereinafter referred to as “G”), blue (hereinafter referred to as “B”), and red (hereinafter referred to as “R”) read by the scanner, and is black (hereinafter referred to as “B”).
k ”. ), Magenta (hereinafter referred to as “M”), yellow (hereinafter referred to as “Y”), and cyan (hereinafter referred to as “C”) image signals. The image processing unit sends the Bk image signal to the writing unit as it is, stores the M, Y, and C image signals in the memory for a time corresponding to the distance from the photoconductor of Bk, and then sends them to the writing unit.

The writing unit includes a laser light source unit, a polygon motor, and a polygon mirror, and irradiates each transfer device with laser light based on the image signal received from the image processing unit.
The transfer device includes a photoconductor, a charging device, a developing device, a P sensor, a transfer device, a cleaning device, and a neutralizer. The charger uniformly charges the photoconductor by corona discharge. The uniformly charged photoconductor forms a latent image by the writing laser beam from the writing section. The developing device develops the latent image on the photoconductor to form a toner image. The P sensor detects the pattern of the toner image developed on the photoconductor. The toner image pattern determines process conditions such as charging potential and developing bias. The transfer device transfers the toner image on the photoconductor to the paper by applying an electric charge from the back side of the transfer belt with the photoconductor and the transfer belt in close contact with the paper. The cleaning device includes a cleaning blade and a cleaning brush, and scrapes off the toner remaining on the photoconductor after transferring the toner image. The static eliminator exposes the photoconductor in order to erase the residual charge on the photoconductor after being cleaned by the cleaning device.

The image memory stores the predetermined specific image data for adjustment and the preset relative positions of the reference image and the comparison image. Here, the image data for adjustment includes, for example, the vicinity of the exposure start position on the exposure start line and the vicinity of the exposure end position on the exposure end line of the first photoconductor located at the most upstream position when the sheet is conveyed. Near the exposure start position on the exposure start line of the first photoconductor, near the exposure end position on the exposure start line, near the exposure end position on the exposure end line, near the exposure start position on the exposure start line of the first photoconductor And near the start position and near the exposure end position on the exposure end line, or near the exposure start position on the exposure start line of the first photoconductor, near the exposure end position on the exposure start line and at the exposure start position on the exposure end line Image data of the reference image of Bk formed in the vicinity and the exposure end position on the exposure end line, and the reference image formed on the first photoconductor on the second to fourth photoconductors as a reference. Distribution of body The position M with relation, Y, comparison image data C in accordance with the.

After the adjustment mode has been set, the adjusting section controls the transfer device so as to set a reference near the exposure start position and the exposure end position of the first photoconductor on the basis of the Bk reference image data stored in the image memory. An image is formed, and comparison images of M, Y, and C are formed on the second to fourth photoconductors so as to have a specific positional relationship with the reference image formed on the first photoconductor. The image formed on the body is transferred to paper. The scanner reads the reference image and the comparison image transferred onto the sheet. The adjustment unit obtains a statistical value of the difference between the actual positional relationship between the reference image and the comparison image read by the scanner and the preset positional relationship as the adjustment value of the exposure timing of the photoconductor, and the obtained adjustment value is set in advance. When the set limit value is exceeded, the user is notified to that effect.

The adjusting unit adjusts the exposure timing by changing the time from the input of the sync mark detection signal indicating the exposure start reference position to the exposure of the photosensitive member and the exposure speed in the main operation direction of the image. , The exposure timing is adjusted by changing the time from the exposure of the first photoconductor to the exposure of the second and subsequent photoconductors.

[0018]

1 and 2 are block diagrams of an electrophotographic apparatus according to an embodiment of the present invention. As shown in the figure, the electrophotographic apparatus includes, for example, a scanner 1, an image processing unit 2, a writing unit 3,
Four transfer devices 4a-4d, transfer belt 5, fixing device 6,
Belt cleaning device 7, image memory 8 and adjusting unit 9
Having. The scanner 1 is a fluorescent lamp 101 and a color CCD 1.
02 is provided. The fluorescent lamp 101 irradiates a color document with light. The reflected light from the color CCD 102 color original is separated into three primary colors of light (green, blue, and red), and a color image on the original is read. The image processing unit 2 reads black (hereinafter “G”), blue (hereinafter “B”) and red (hereinafter “R”) image data read by the scanner, and then black (hereinafter “Bk”). Image signals of magenta (hereinafter referred to as “M”), yellow (hereinafter referred to as “Y”), and cyan (hereinafter referred to as “C”). The image processing unit 2 sends the Bk image signal as it is to the writing unit 3, stores the M, Y, and C image signals in the image memory 8 for a time corresponding to the distance from the photoconductor of Bk, and then sends them to the writing unit 3. .

The writing unit 3 is a laser light source unit (not shown),
A polygon motor 302 and an upper polygon mirror 303, a lower polygon mirror 304, an fθ lens 305, a first mirror 306, a second mirror 307 and a third mirror 308 are provided. The laser light source unit 301 uses Bk from the image processing unit 2,
Laser light for exposing the transfer devices 4a to 4d for Bk, M, Y, and C colors is generated based on the M, Y, and C image signals. Upper polygon mirror 303 and lower polygon mirror 30
4 is rotated by the driving force from the polygon motor 302. The upper polygon mirror 303 reflects the laser light from the laser light source unit and exposes the transfer device 4b for M and the transfer device 4c for Y. The lower polygon mirror 304 reflects the laser light from the laser light source unit 301, and exposes the Bk transfer device 4a and the C transfer device 4d.

Transfer device 4a for each color of Bk, M, Y and C
4d are the photoconductor 41, the charging device 42, and the developing device 4, respectively.
3, a P sensor (not shown), a transfer device 44, a cleaning device 45, and a static eliminator 46. The photoconductor 41 of each of the transfer devices 4a to 4d transfers an image of each color of Bk, M, Y, and C onto the paper. The charger 42 uniformly charges the photoconductor 41 by corona discharge. The uniformly charged photoconductor 4 forms a latent image by the writing laser light from the writing unit 2. The developing device 4 develops the latent image on the photoconductor 41 to form a toner image. The P sensor detects the pattern of the toner image developed on the photoconductor 41. The pattern of the detected toner image determines process conditions such as charging potential and developing bias. The transfer device 44 includes the photoconductor 41 and the transfer belt 5.
By applying an electric charge from the back side of the transfer belt 5 in a state of being in close contact with the paper, the toner image on the photoconductor 41 is transferred to the paper. The cleaning device 45 includes a cleaning blade and a cleaning brush, and scrapes off the toner remaining on the photoconductor 41 after transferring the toner image. The static eliminator 46 exposes the photoconductor 41 in order to erase the residual charges on the photoconductor 41 after being cleaned by the cleaning device 45.

The image memory 8 includes an image data storage section 81, an adjustment image data storage section 82, and a position reference data storage section 8.
3 is provided. The image data storage unit 81 stores the image data transferred by the scanner 1 onto the reading paper. The adjustment image data storage unit 82 stores predetermined specific image data for adjustment. The position reference data storage unit 83 stores the set relative positions of the reference image and the comparison image. Here, the image data for adjustment is, for example, reference image data of Bk formed near the exposure start position and the exposure end position of the Bk photoconductor 41a located at the most upstream when the sheet is conveyed, and The image data for comparison of M, Y, and C formed on the other photoconductors 41b to 41d so as to have a specific positional relationship with the reference image formed on the photoconductor 41a for Bk.

The adjusting section 9 includes an adjusting image writing control means 91,
The comparison means 92 and the exposure timing control means 93 are provided.
After the adjustment mode is set, the adjustment image writing control unit 91 controls the writing unit 3 and the transfer devices 4a to 4d, and stores B in the adjustment image data storage unit 82 of the image memory 8.
Based on the reference image data of k, a reference image is formed in the vicinity of the exposure start position and the exposure end position of the photoconductor 41 of the Bk transfer device 4a, and the photoconductors 4 of the other transfer devices 4b to 4d are formed.
1. A comparative image of M, Y, C is formed on the photosensitive member 41 of the transfer device 4a for Bk so as to have a specific positional relationship with the reference image, and the photosensitive member of each of the transfer devices 4a to 4d is formed. 41
The image formed above is transferred to a sheet. After reading the reference image and the comparison image formed on this sheet with the scanner 1,
The comparison unit 92 adjusts the exposure timing of the photoconductor 41 of each of the transfer devices 4a to 4d using the statistical value of the difference between the actual positional relationship between the reference image read by the scanner 1 and the comparative image and the preset positional relationship. If the calculated adjustment value exceeds a specific limit value, the user is notified of that fact through, for example, an operation display unit (not shown). The exposure timing control unit 93 adjusts the exposure timing based on the adjustment value obtained by the comparison unit 92.

The exposure timing adjusting operation in the electrophotographic apparatus having the above structure will be described with reference to the flowchart of FIG.

For example, when the user specifies an adjustment mode on the operation display unit and gives an instruction for exposure timing adjustment, the writing unit 3 controls the adjustment image writing control means 91 to control the adjustment image data from the image memory 8. Read out (step S1). The writing unit 3 is based on the read image data for adjustment and, for example, as shown in FIG.
A latent image is formed on the photoconductor 41 of a by the reference image data, the photoconductor 41 of the transfer device 4b for M, the photoconductor 41 of the transfer device 4c for Y, and the photoconductor 41 of the transfer device 4d for C.
A latent image is formed on the image data for comparison (step S
2). Here, the images based on the reference image data and the comparison image data are formed on the paper by the photoconductor 4 of each of the transfer devices 4a to 4d.
An image is alternately formed in the main scanning direction and the sub scanning direction according to the position of one photoconductor, but the pattern may be adjusted using other patterns.

Transfer device 4a for each color of Bk, M, Y and C
4d to 4d respectively transfer the image formed on the photoconductor 41 to a sheet and fix it by the fixing device 6. The user sets the paper on which the reference image and the comparison image are written in the scanner 1,
The reference image and the comparison image are read from the scanner 1 (step S3). The comparing means 92 of the adjusting unit 9 is, for example, as shown in FIG.
As shown in, the positional relationship between the reference image read by the scanner 1 and the comparison image is detected (step S4). here,
In the figure, a indicates a shift in the main scanning direction between the reference image and the M comparison image, b indicates a shift in the sub scanning direction between the reference image and the M comparison image, and c indicates the first reference image and the next reference image. The distance in the main scanning direction of the image is shown, and d is the distance in the sub scanning direction between the first reference image and the next reference image. The deviation between the first reference image and the next reference image is obtained by subtracting the reference distance stored in the position reference data storage unit 83 from the above c and d. Comparison means 92
Is a statistical value of the difference between the detected positional relationship between the reference image and the comparative image and the preset positional relationship between the reference image and the comparative image, and adjusts the exposure timing of the photoconductor 41 of the transfer devices 4a to 4d. The value is obtained (step S5). When the calculated adjustment value exceeds a specific limit value (step S6), the comparison means 92 notifies the user of that fact via the operation display unit 10 (step S7). Comparison means 9
If the adjustment value obtained by No. 2 does not exceed the specific limit value (step S6), the exposure timing control means 93 uses the adjustment value obtained by the comparison means 92 to detect the photoconductor 41 of each of the transfer devices 4a to 4d. Adjust the exposure timing (step S
8). As described above, the exposure timing of the photoconductors 41a to 51d is automatically adjusted using the result of printing the reference image and the comparison image, so that the adjustment process can be simplified and the adjustment result is always uniform. Can be kept at

Here, in order to adjust the exposure timing of the photoconductors 41 of the transfer devices 4a to 4d to be written based on the adjustment value obtained by the comparison means 92, the writing section 3 is constructed as shown in FIG. Adjusting the exposure timing by controlling the timing control clock by changing the time from the input of the sync mark detection signal indicating the exposure start reference position to the exposure of the photoconductor and the exposure speed in the main operation direction of the image. It may be done.

Further, the writing unit 3 is configured as shown in FIG. 7, for example, from the exposure of the photoconductor 41 of the Bk transfer device 4a to the exposure of the photoconductor 41 of the other transfer devices 4b to 4d. The exposure timing may be adjusted by changing the time.

[0028]

As described above, the present invention forms a predetermined specific adjustment image on each photoconductor, transfers the adjustment image formed on each photoconductor to a sheet, and transfers it to the sheet. Since the adjusted image is read and the exposure timing of each photoconductor is adjusted based on the read adjusted image, the number of adjustment steps can be reduced.

Further, a reference image is formed on the first photoconductor located on the most upstream side when the sheet is conveyed, and a comparative image is formed on the second and subsequent photoconductors according to the arrangement of the photoconductors. ,
The image formed on each photoconductor is transferred to a sheet, the reference image and the comparison image transferred to the sheet are read, and the relative positions of the read reference image and the comparison image and the preset reference image and comparison image Since the exposure timings of the second and subsequent photoconductors are adjusted based on the difference from the relative position of, the adjustment can be performed easily and accurately.

Further, as the adjustment value of the exposure timing of the photoconductor, the statistical value of the difference between the relative position between the actual reference image and the comparison image and the preset relative position between the reference image and the comparison image is obtained. It is possible to stabilize the adjustment value of the exposure timing of the photoconductor.

Further, when the calculated adjustment value exceeds a preset limit value, the user is notified of that fact, so that it is possible to prevent the photosensitive member from being exposed in the state of poor adjustment.

Further, the exposure timing is adjusted by changing the time from the input of the sync mark detection signal indicating the exposure start reference position to the exposure of the photoconductor and the exposure speed in the main operation direction of the image, so that the main scanning is performed. The exposure timing in the direction can be made precise.

Further, after exposing the first photoconductor to the second photoconductor,
Since the exposure timing is adjusted by changing the time until the subsequent exposure of the photosensitive member, the exposure timing in the sub-scanning direction can be made accurate.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of an adjustment unit and an image memory.

FIG. 3 is a flowchart showing an operation of exposure timing adjustment.

FIG. 4 is a layout view of an adjustment image printed on a sheet.

FIG. 5 is an explanatory diagram showing a shift of an adjustment image.

FIG. 6 is a configuration diagram of a writing unit.

FIG. 7 is a configuration diagram of another writing unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scanner 2 Image processing unit 3 Writing unit 4 Transfer device 41 Photoconductor 8 Image memory 81 Image data storage unit 82 Image data storage unit for adjustment 83 Position reference data storage unit 9 Adjustment unit 91 Adjusted image writing control unit 92 Comparison unit 93 Exposure timing control means

Claims (5)

[Claims] 1. An electrophotographic apparatus for exposing a plurality of photoconductors respectively to form monochromatic images of different colors on the photoconductors and sequentially transferring the monochromatic images formed on the photoconductors to a sheet. Form a specific adjustment image on each photoconductor, transfer the adjustment image formed on each photoconductor to paper,
An electrophotographic apparatus, which reads an adjustment image transferred onto a sheet, and adjusts the exposure timing of each photoconductor based on the read adjustment image. 2. The first photoconductor is exposed near the exposure start position on the exposure start line and the exposure end line is near the exposure end line of the first photoconductor located at the most upstream side when the sheet is conveyed. Near the exposure start position on the line, near the exposure end position on the exposure start line, near the exposure end position on the exposure end line, near the exposure start position on the exposure start line of the first photoconductor, and on the exposure end line Near the position and near the exposure end position on the exposure end line, or near the exposure start position on the exposure start line of the first photoconductor, near the exposure end position on the exposure start line, and near the exposure start position on the exposure end line. A reference image is formed in the vicinity of the exposure end position on the exposure end line, and has a positional relationship corresponding to the arrangement of each photoconductor on the second and subsequent photoconductors with the reference image formed on the first photoconductor as a reference. Image for comparison Formed and transferred the image formed on each photoconductor to paper, read the reference image and the comparison image transferred to the paper, and compare the relative position of the read reference image and the comparison image with the preset reference image The electrophotographic apparatus according to claim 1, wherein the exposure timing of the second and subsequent photoconductors is adjusted based on the difference from the relative position of the image. 3. A statistical value of the difference between the relative position between the actual reference image and the comparison image and the preset relative position between the reference image and the comparison image as the adjustment value of the exposure timing of the photoconductor, The electrophotographic apparatus according to claim 2, wherein when the calculated adjustment value exceeds a preset limit value, the user is notified of that fact. 4. The exposure timing is adjusted by changing the time from the input of the sync mark detection signal indicating the exposure start reference position to the exposure of the photoconductor and the exposure speed in the main operation direction of the image. 2. The electrophotographic apparatus according to 2. 5. The electrophotographic apparatus according to claim 2, wherein the exposure timing is adjusted by changing the time from the exposure of the first photoconductor to the exposure of the second and subsequent photoconductors.