JPH0885236A - Color image forming device - Google Patents

Abstract

PURPOSE: To output, by signal processing at high speed, color images whose misregistrations in image stations are corrected. CONSTITUTION: Based on a quantity of misregistration to be decided by formed coordinate information of each pattern generated by a coordinate data generation means for generating formed coordinate information of each pattern transferred to a transfer belt 10 from each test pattern image information which is read by CCD sensors 14A, 14B and predetermined reference position information, a coordinate conversion means automatically converts an output coordinate position of image data at every color into an output coordinate position whose misregistration is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus for forming a color image by arranging a plurality of image carriers side by side and successively transferring images of different colors onto a recording medium to be conveyed.

[0002]

2. Description of the Related Art Conventionally, as a color image forming apparatus using an electrophotographic system, one photoconductor is developed with a plurality of developing devices for each color, and a plurality of exposure-development-transfer steps are performed. A method is generally used in which a color image is formed by superposing it on one sheet of transfer paper by repeating it repeatedly and then fixed to obtain a full-color image.

[0003]

According to this method, 1
In order to obtain one print image, it is necessary to repeat the image forming process 3 to 4 times (when black is used), which has a drawback that it takes time.

As a method for compensating for this drawback, there is a method in which a plurality of photoconductors are used and the visible images obtained for each color are successively superposed on the transfer paper to obtain a full-color print in one pass. According to this method, the throughput can be significantly reduced, but on the other hand, due to the positional accuracy and diameter deviation of each photoconductor, the positional accuracy deviation of the optical system, etc., the color due to the positional deviation on the transfer paper of each color There was a problem of misalignment, and it was difficult to obtain a high-quality full-color image.

As a method for preventing this color misregistration, for example, a test toner image is formed on a transfer paper or a conveyor belt which is a part of the transfer means, and this is detected, and based on this result. A method of correcting the optical path of each optical system or correcting the image writing position of each color (see Japanese Patent Laid-Open No. 64-40956, etc.) can be considered, but this method causes the following problems. .

First, in order to correct the optical path of the optical system, a correction optical system including a light source and an f-θ lens, a mirror in the optical path, etc. are mechanically operated to align the position of the test toner image. Although it is necessary, a highly accurate movable member is required for this purpose, resulting in an increase in cost. Further, since it takes a long time to complete the correction, it is impossible to perform the correction frequently. However, the deviation of the optical path length may change with time due to the temperature rise of the machine. It is difficult to prevent color misregistration by correcting the optical path of the optical system.

Secondly, by correcting the writing position of the image, it is possible to correct the positional deviation of the left end and the upper left part, but it is possible to correct the inclination of the optical system and the magnification deviation due to the deviation of the optical path length. There was a problem that it could not be done.

The present invention has been made to solve the above problems, and an object of the first to third inventions of the present invention is to form a registration mark and a reference for a registration mark formed at each image station. The position shift coordinate position is calculated by comparing with the position, and the output position of each color image input based on the calculated position shift coordinate position is converted into the corrected output position, thereby It is an object of the present invention to provide a color image forming apparatus capable of outputting a color image in which registration deviation of each image station is corrected at high speed by signal processing without mechanically correcting the arrangement of an optical scanning system.

[0009]

According to a first aspect of the present invention, there is provided a photoconductor, and exposure means for irradiating the photoconductor with a light beam modulated by each color signal to form an electrostatic latent image. An image having a developing unit that visualizes the electrostatic latent image formed on the photoconductor by the exposing unit, and a transfer unit that transfers each color image visualized by the developing unit onto a transfer paper. In a color image forming apparatus in which a plurality of stations are juxtaposed and a color image formed by each image station is sequentially transferred to a transfer material conveyed by a conveying unit to form a color image, a predetermined registration deviation is detected. Test pattern generating means for generating test pattern data, storage means for storing the test pattern data of each color generated by the test pattern generating means, and read from the storage means. Reading means for reading the test pattern image formed on each of the image stations and transferred onto the carrying means based on the test pattern data of each color, and the test pattern image information read by the reading means is transferred to the carrying means. The image for each color is generated based on the coordinate data generating means for generating the formation coordinate information of each pattern and the deviation amount determined from the formation coordinate information of each pattern generated by the coordinate data generating means and the predetermined reference position information. Coordinate conversion means for automatically converting the output coordinate position of the data into the output coordinate position in which the registration deviation is corrected, and the image data of each color converted by this coordinate conversion means is expanded in the storage means and the expanded Each exposure means of each image station exposes a light beam modulated based on image data onto each photoreceptor. It is obtained by configured to.

According to a second aspect of the present invention, the reading means is a test pattern formed in each image station based on the test pattern data of each color read from the storage means and transferred to the transfer material on the conveying means. It is configured to read an image.

According to a third aspect of the present invention, a reader unit for optically reading an original image, a photoconductor, and a light beam modulated by each color signal based on each color image information output from the reader unit are exposed. Exposure means for irradiating the body to form an electrostatic latent image, developing means for making the electrostatic latent image formed on the photoconductor by the exposing means visible, and color images made visible by the developing means A plurality of image stations each having a transfer unit for transferring the image onto a transfer sheet, and a printer unit that forms a color image by sequentially transferring the color images formed by the image stations to the transfer material conveyed by the conveying unit. A color image forming apparatus comprising: a printer unit configured to print a registration mark having a predetermined pattern having reference coordinates at each image station of the printer unit on the transfer paper; Test mode processing means, and second test mode processing means for reading the registration mark formed on the transfer material by the first test mode processing means from the reader part to detect the coordinates of the formation position of the registration mark. The registration deviation of the output coordinate position of the image data for each color is corrected based on the deviation amount determined from the registration position forming coordinates of the registration mark detected by the second test mode processing means and the predetermined reference coordinates. Coordinate conversion means for automatically converting to output coordinate positions, image data of each color converted by the coordinate conversion means is expanded in the storage means, and a light beam modulated based on the expanded image data is generated. Each exposure means of each image station is configured to expose on each photoconductor.

[0012]

In the first aspect of the invention, the formation coordinate information of each pattern generated by the coordinate data generating means for generating the formation coordinate information of each pattern transferred to the conveying means from each test pattern image information read by the reading means. The coordinate conversion means automatically converts the output coordinate position of the image data of each color into the output coordinate position in which the registration shift is corrected based on the shift amount determined from the predetermined reference position information and the converted color of each color. The image data is expanded in the storage means, and the light beam modulated based on the expanded image data is exposed on each photoconductor by each exposure means of each image station, whereby the mechanical arrangement of the optical scanning system is shifted. Even if registration misalignment caused by, for example, image registration occurs at each image station, each color image is placed at the position where the registration misalignment is canceled. Because Deployment outputs, making it possible to output a color image without color misregistration at a high speed.

In the second invention, the reading means reads the test pattern image formed in each image station based on the test pattern data of each color read from the storage means and transferred to the transfer material on the conveying means. , It is possible to accurately detect the registration deviation amount of each image station.

In the third aspect of the invention, the registration mark formed of a predetermined pattern having the reference coordinates is printed on the transfer sheet by the first test mode processing means in each image station of the printer section. The registration mark is read from the reader unit and the second
When the test mode processing means of (1) detects the formation position coordinates of the registration mark, the coordinate conversion means for each color is based on the deviation amount determined from the detected formation position coordinates of the registration mark and predetermined reference coordinates. The output coordinate position of the image data is automatically converted into the output coordinate position in which the registration shift is corrected, the converted image data of each color is expanded in the storage means, and the light beam modulated based on the expanded image data Even if the registration deviation due to the mechanical arrangement deviation of the optical scanning system, etc. occurs in each image station by each exposure means of each image station exposing each photoconductor, it is output from the printer section. The registration mark image is read by the reader unit, and each color image is output by each image station at a position that cancels the registration deviation. Since, it makes it possible to output a color image without color misregistration at a high speed.

[0015]

【Example】

[First Embodiment] FIG. 1 is a schematic sectional view for explaining the configuration of a color image forming apparatus showing a first embodiment of the present invention, which corresponds to, for example, a 4-drum type color laser beam printer.

In the figure, 1C is an OPC photosensitive drum for cyan, a drum unit 9C including a cleaner 8C and a charging roller 2C, a developing sleeve 5C, a coating roller 4C,
An integral type process cartridge is constituted by a developing unit 7C including a non-magnetic one-component developer 3C and a coating blade 6C. 11C is a transfer roller, which is a roller 12,
The developed color images are transferred onto the transfer paper P transferred onto the transfer belt 10 conveyed by the transfer belt 13.

The transfer sheet P is housed in a cassette 26, and is raised by a spring 25 so that the transfer sheet P on the upper surface side comes into contact with the pickup roller 19. 20, 2
A transfer roller 1 transfers the transfer paper P separated by the pickup roller 19 in the direction in which the registration rollers 22 are arranged. Reference numeral 16 is a heat fixing roller, which heats and fixes the toner image transferred onto the transfer paper P by the pressure roller 17. 18C
Is a laser scanning device, which emits a scanning beam 28C modulated based on an image signal. Reference numeral 27 denotes a printer main body casing (printer unit). A transport roller 23 transports the transfer paper P, which has undergone the heat fixing process, in the direction in which the paper discharge roller 24 is disposed.

CCD sensor portions 14A and 14B are image information reflected when a registration mark for detecting a registration position deviation amount, which will be described later, transferred to the transfer belt 10 by the exposure lamps 29A and 29B is illuminated. To read. The registration mark (toner image) contained in the read image is cleaned by the cleaner 15 to remove the residual toner.

1M is an OPC photosensitive drum for magenta,
Drum unit 9 including cleaner 8M and charging roller 2M
Developing unit 7 including M and developing sleeve 5M, coating roller 4M, non-magnetic 1-component developer 3M, coating blade 6M
An integrated process cartridge made of M is configured. Reference numeral 11M is a transfer roller, which transfers each color image developed on the transfer paper P transferred onto the transfer belt 10 conveyed by the rollers 12 and 13. A laser scanning device 18M emits a scanning beam 28M modulated based on an image signal.

1Y is an OPC photosensitive drum for yellow,
Drum unit 9 including cleaner 8Y and charging roller 2Y
Developing unit 7 including Y and developing sleeve 5Y, coating roller 4Y, non-magnetic one-component developer 3Y, coating blade 6Y
An integrated process cartridge made of Y is configured. Reference numeral 11Y is a transfer roller, which transfers the developed color image onto the transfer paper P transferred onto the transfer belt 10 conveyed by the rollers 12 and 13. A laser scanning device 18Y emits a scanning beam 28Y modulated based on an image signal.

1K is an OPC photosensitive drum for black,
Drum unit 9 including cleaner 8K and charging roller 2K
K and developing sleeve 5K, coating roller 4K, non-magnetic one-component developer 3K, coating blade 6K
An integral process cartridge made of K is configured. Reference numeral 11K denotes a transfer roller, which transfers each color image developed on the transfer paper P transferred to the transfer belt 10 conveyed by the rollers 12 and 13. A laser scanning device 18K emits a scanning beam 28K which is modulated based on an image signal.

FIG. 2 is a block diagram for explaining the construction of the registration correction circuit of the color image forming apparatus shown in FIG. 1. The same parts as those in FIG. 1 are designated by the same reference numerals.

In the figure, 31 is a reference signal generating means,
Coordinate data generating means 2-33 and line memory 36
A predetermined reference signal is output to C, 36M, 36Y and 36K. 35C, 35M, 35Y, and 35K are bit map memories, and image data DC, DM, DY, and DK output from the coordinate conversion means 2-34 or pattern image data PDC and P output from the test pattern generation means 32.
Store DM, PDY, PDK.

37C, 37M, 37Y and 37K are pulse width modulation circuits, which are line memories 36C, 36M, 36Y,
Laser scanning device 1 based on data stored in 36K
The 8C, 18M, 18Y and 18K semiconductor lasers are driven to emit scanning beams 28C, 28M, 28Y and 28K.

Correspondence between this embodiment and each means of the first and second inventions and their operation will be described below with reference to FIG.

A first aspect of the present invention is a photosensitive member (photosensitive drum 1C,
1M, 1Y, 1K) and exposure means (laser scanning devices 18C, 18M, 18Y, 18K) for irradiating the photoconductor with a light beam modulated by each color signal to form an electrostatic latent image.
And a developing means (developing units 7C, 7M, which develops the electrostatic latent image formed on the photoconductor by the exposing means).
7Y, 7K) and a plurality of image stations ST1 to ST4 each having a transfer means for transferring each color image visualized by the developing means onto a transfer paper, and the color images formed by the respective image stations are displayed. In a color image forming apparatus for forming a color image by transferring to a transfer material sequentially conveyed by a conveying means, a test pattern generating means 32 for generating test pattern data for detecting a predetermined registration deviation, and the test pattern. Generating means 3
Storage means (bit map memories 35C, 35M, 35Y,
35K) and reading means (CCD sensor sections 14A, 14) for reading the test pattern image formed on each image station and transferred onto the conveying means based on the test pattern data of each color read from the storage means.
B), and coordinate data generating means 2-33 for generating formation coordinate information of each pattern transferred to the conveying means from each test pattern image information read by the reading means,
The output coordinate position of the image data for each color is set to the output coordinate position in which the registration shift is corrected based on the shift amount determined from the formation coordinate information of each pattern generated by the coordinate data generating means and the predetermined reference position information. The CCD sensor unit 14 having a coordinate conversion unit 2-34 for automatic conversion.
Forming coordinate information of each pattern generated by the coordinate data generating means 2-33 for generating forming coordinate information of each pattern transferred to the transfer belt 10 from each test pattern image information read by A and 14B and a predetermined reference position. The coordinate conversion means 2-34 automatically converts the output coordinate position of the image data for each color into the output coordinate position corrected for the registration shift based on the shift amount determined from the information, and the converted image data of each color. The bit map memories 35C, 35
M, 35Y, 35K, and a laser beam 18C, 18M, 18Y, 18K of each image station exposes a light beam modulated on the basis of the developed image data onto each photoconductor, Even if registration error due to mechanical displacement of the optical scanning system occurs in each image station, each image station outputs each color image at a position that cancels the registration error, so that there is no color deviation. It is possible to output images at high speed.

According to a second aspect of the invention, the reading means (CCD sensor sections 14A and 14B) is formed at each image station based on the test pattern data of each color read from the storage means and transferred to the transfer material on the conveying means. It is possible to read the prepared test pattern image and accurately detect the registration deviation amount of each image station.

FIG. 3 is a block diagram for explaining a data processing configuration when a color original reading device is connected to the color image forming apparatus shown in FIG. The same reference numerals are attached.

In the figure, reference numeral 41 denotes an original, and the reflected light from an optical scanning means (not shown) is color-separated into three primary colors of R, G and B, and then multivalued color signals are obtained by CCD sensors 42R, 42G and 42B. Is converted to. 43R, 43G, 4
3B is an A / D converter, and CCD sensors 42R, 42G,
The multi-valued color signal output from 42B is converted into a digital signal corresponding to the brightness and output to the shading correction circuits 44R, 44G, and 44B, respectively. 45R, 45
G and 45B are gamma conversion units, which are complementary colors of yellow (Y), magenta (M), and cyan (C) corresponding to R, G, and B of the brightness data subjected to shading correction by the shading correction circuits 44R, 44G, and 44B. Image data C ', M', Y '.

Reference numeral 46 is a black data generating circuit which extracts black image data K'from the image data C ', M', Y '. Reference numeral 47 is a masking processing circuit, which is an image data C ′,
Predetermined masking processing is performed on M ′, Y ′, and K ′. 48C, 48M, 48Y, and 48K are gamma conversion units that perform gradation correction so that the gradation characteristics of the image data C ′, M ′, Y ′, and K ′ match the gradation characteristics of the printer.

First, the color image data generation processing operation in the color image forming apparatus according to the present invention will be described.

As the color image data, a graphic image of a computer device may be taken out as a signal, or a color original may be read by a color reader or the like and printed.

In the former case, if a full-color signal is generated by a computer, it can be used as it is as image data. In the latter case, image data is generated by performing image processing as shown in the reader section in FIG.

That is, in FIG. 3, the original 41 composed of a full-color image is separated into three primary colors of red (R), green (G), and blue (B) by an appropriate optical means (not shown), and then, The CCD sensors 42R, 42G, and 42B respectively convert the multi-valued color signals. Here, in order to obtain a good image, the resolution of the optical system is preferably about 400 to 600 dots / inch.

Next, the CCD sensors 42R, 42G, 42
The analog output of B is the A / D converters 43R and 43R.
It is converted into a digital value according to the brightness by G and 43B. At this time, in order to obtain a good image, it is preferable that the gradation level is 64 to 256 or more. The brightness data obtained in this way passes through the shading correction circuits 44R, 44G and 44B for correcting the variation of each pixel of the optical system and the CCD sensor, and the gamma conversion unit 45R,
The red, green, and blue of the luminance data are converted into corresponding complementary colors of cyan (C '), magenta (M'), and yellow (Y ') by 45G and 45B (that is, inverse logarithmic conversion).

The C ', thus obtained,
From the data of M ′ and Y ′, the black data generation circuit 46
Black (K ') data is extracted. Although various methods are used for this, as an example, a method of setting the minimum value of C ′, M ′, Y ′ as black data can be used. Masking is performed by the masking processing circuit 47 using the image data of C ′, M ′, Y ′, and K ′ thus obtained.
Generally, as a masking method,

[0037]

[Equation 1] A matrix of the following formula 1 is created and, for example, C ″ = a
₁₁ C ′ + a ₁₂ M ′ + a ₁₃ Y ′ + a ₁₄ · fn (K ′), where f (K ′) is a polynomial of degree n with respect to K ′ data. Then, the calculation is performed on C ″, M ″, Y ″, and K ″.

It should be noted that a11 to a44 are constants which are appropriately obtained by experiments, but since they are not a part relating to the essence of the present invention, detailed description thereof will be omitted.

Next, in order to match the image data C ", M", Y ", and K" generated by the masking process with the gradation characteristics of the printer, gamma conversion units 48C, 48M, 48.
Gradation correction is performed with Y and 48K.

The image data C obtained as described above,
A printer unit for printing M, Y, and K will be described with reference to FIG.

First, image signals C, M, Y having gradations,
K is a pulse width modulation circuit 37C to
After modulating the pulse width corresponding to the laser ON time by 37K, the laser scanning devices 18C, 18M, 18Y,
Input to 18K.

FIG. 4 shows the laser scanning device 18 shown in FIG.
It is a schematic diagram explaining the composition of C. The same applies to the laser scanning devices 18M, 18Y, and 18K.

As shown in this figure, the cyan image signal C
Is pulse-width modulated and then input to the laser drive circuit 51C to turn on the semiconductor laser 52C including a collimator lens.
Drive off. Next, the laser beam made parallel by the collimator lens is flattened by the cylindrical lens 53C and incident on the polygon mirror 54C to become a scanning beam.

After that, the scanning beam 2 is transmitted through the correction optical system 55C of the second group having the f-θ characteristic and the beam shaping function.
8C is output. Reference numeral 56C is a beam detector (BD) for detecting a part of the scanning beam and giving a vertical synchronizing signal, and 57C is a reflecting mirror. The scanning beams 28C, 28M, 28Y, 28K output in this way
Respectively enter the corresponding photosensitive drums 1C, 1M, 1Y, 1K.

The operation will be described below by taking the cyan scanning beam 28C as an example.

The OPC photosensitive drum 1C comprises a drum unit 9C including a cleaner 8C and a charging roller 2C, a developing sleeve 5C, a coating roller 4C, a non-magnetic component developer 3C,
The photosensitive drum 1C is first uniformly and negatively charged by the charging roller 2C. The photosensitive drum 1C is provided in the integrated process cartridge including the developing unit 7C including the coating blade 6C. Next, the scanning beam 28C receives an exposure corresponding to the color information of the image, and an electrostatic latent image is formed on the photosensitive drum 1C. Then, the developer 3C carried on the surface of the phenomenon sleeve 5C reversely develops the exposed portion of the laser beam. The cyan image TC obtained as a visible image on the photosensitive drum 1C is obtained by the transfer roller 1 to which a positive bias is applied.
It is transferred onto the transfer paper P on the transfer belt by 1C.

The residual toner on the photosensitive drum 1C is collected by the cleaner 8C. The transfer paper P is pressed against the pickup roller 19 from inside the cassette 26 by the spring 25, and is fed by the rotation of the roller 19. The surface of the transfer paper P placed on the transfer belt 11 rotated by the transfer rollers 11C, 11M, 11Y and 11K and the rollers 12 and 13 via the transport rollers 20 and 21 and the registration roller 22 is described above. Cyan image T
C, magenta image TM, yellow image TY, and black image TK are provided on the rear surface of the transfer belt, and are sequentially transferred by the transfer rollers 11C, 11M, 11Y, and 11K to which a positive bias is applied so as to be superposed.

Then, each color passes between the heat fixing roller 16 and the pressure roller 17, and the respective colors are fused and fixed.
3. The paper is ejected outside the printer 27 via the paper ejection roller 24.

Here, the transfer belt 10 has a volume resistivity of 1
It is preferable to use a dielectric substance of about 0 ¹¹ to 10 ¹⁶ Ωcm. In this embodiment, the volume resistivity of the white pigment dispersed is about 10 ¹² Ω.
200μ of semi-conductive polycarbonate resin film of about cm
Transfer rollers 11C to 1C having a thickness of m
As 1K, chloroprene rubber having a diameter of 20 mm and a volume resistivity of about 10 ⁵ Ωcm was used. As a transfer bias, a constant current power source (not shown) applies a positive current of about 10 to 20 μA to the back surface of the transfer belt from each transfer roller to obtain good transfer. The adhesion of the transfer paper P was also good.

In the above description, it goes without saying that the gamma conversion units 48C to 48K as the gradation correction means in FIG. 3 may be provided in the printer unit.

Next, a description will be given of a device for preventing C, M, Y, and K color shifts in the above-described full-color printer.

First, in FIG. 1, prior to the actual printing, first, a registration mark for detecting the printing position is formed on the transfer belt 10. The registration mark may have any shape as long as it is suitable for position detection, but if one having a shape of “#” as shown in FIG. 5 is used as an example, the edge portion of the vertical / horizontal line is used. And excellent position detection is possible.

Next, the formed resist mark is CCD with a condenser lens by the reflected light of the exposure lamps 29A and 29B.
It is read by the sensor units 14A and 14B. After that, the registration mark after the reading is finished is cleaned by the cleaner 15.

Next, the method of generating and reading the above-mentioned registration mark will be described in detail.

First, in the registration mark generation, the test pattern generating means 32 of FIG. 2 generates an image as shown in FIG. 5 as a dot pattern, and this dot signal is not passed through the coordinate converting means 34, but C, M, Y. , K are stored in the bit map memories 35C, 35M, 35Y, and 35K.

Here, the method of writing and reading the registration mark in the case of cyan color will be described.

First, the coordinate designated by the registration mark (for example, the central portion of the "#" pattern shown in FIG. 5) is set to A
(X ₁ , y ₁ ), B (x ₂ , y ₁ ), C (x ₁ , y
₂ ) and D (x ₂ , y ₂ ) at four positions, and the four registration marks formed in a dot pattern centering on these coordinates are each converted into a dot shape, and the corresponding bit map The size of the bitmap memories 35C, 35M, 35Y, 35K, etc. stored in the memory 35C was larger than the maximum image data.

Then, the transfer belt 10 of FIG. 1 and the process cartridge of each color are driven at a predetermined timing, and in synchronization with the reference signal generating means 31, corresponding to each dot of the bit map memory 35C, Four resist patterns are formed on the transfer belt 10.

More specifically, the bit map memory 35
The data for each scanning line of C is temporarily stored in the line memory 36.
The signal is sequentially read by C and is synchronized with the vertical synchronizing signal and the reference signal generated by the beam detect signal of the laser scanning device 18C, and sequentially sent to the laser drive circuit 51C of FIG. 4 via the pulse width modulation circuit 37C. The
A resist mark is formed by driving the semiconductor laser 52C on and off.

The registration marks thus obtained on the transfer belt 10 are formed at four predetermined positions on the transfer belt unless the optical system and the mechanical position accuracy are essentially correct. Will be.

However, when the mechanical accuracy of the laser scanning device 18C is deviated, for example, the inclination of the reflection mirror 57C or the focal length is deviated, or the drum unit 9c is changed.
The position indicated by the registration mark on the transfer belt 10 due to the relative displacement of the laser scanning device 18C, the transfer belt 10, etc. is actually A → A ′, B →
A shift such as B ′, C → C ′, D → D ′ occurs.

At this time, the CCD is brought close to the transfer belt 10.
The sensor units 14A and 14B are provided, and the exposure lamps 29A and 29B are provided.
By irradiating and reading the above-mentioned registration mark by the coordinate data generating means 33 from the reading timing of the registration mark (that is, the sub-scanning position) and the position with respect to the CCD element in the main scanning direction. By generating the position data, A '(x ₁ ', y ₁ '), B'is actually generated.
(X ₂ ', y ₁ "), C' (x ₁ ", y ₂ '), D' (x ₂ ", y
₂ ") coordinates can be known.

In this embodiment, two 256-element CCD sensors are used, and the registration mark on the transfer belt 10 is 60.
The lenses (not shown) in the CCD sensor units 14A and 14B were adjusted so that the CCD device could read with a resolution of 0 dots / inch.

With respect to the coordinates thus obtained,

[0065]

[Number 2] _{Δx 1 = x 1 '-x 1} Δx 2 = x 2' -x 2 Δy 1 = y 1 '-y 1 Δy 1' = y 1 "-y 1 Δy 2 = y 2 '-y 2 Based on the above equation 2, Δx ₁ , Δx ₂ , Δy ₁ , Δ
Defining y ₁ ', Δy ₂ , the true coordinate Q (x, y)
And the actual coordinate Q ′ (x ′, y ′) are obtained by the following mathematical formula 3.

[0066]

(Equation 3) That is, the coordinates A ', B',
If C'and D'are measured, from this result, C _{1 to} C ₅
By calculating and storing it in the coordinate conversion means 34, the printing position when printing on the transfer paper P can be corrected on the bitmap memory 35C by using the above-described mathematical expression 3.

Specifically, before printing, at the time of pre-rotation, etc., a registration mark is generated and C _{1 to} C ₅ are obtained, and then the coordinates of each image data are converted into Q '(x ', Y') (that is, the coordinates of the original image data)
Therefore, by sequentially converting into Q (x, y) by using the above-mentioned mathematical expression 3, an image can be formed at the correct corresponding position on the transfer belt 10. In addition, as the coordinate conversion means 34,
A microcomputer with a built-in memory, an arithmetic circuit, or the like can be used.

For example, the x and y coordinates are made to correspond to the bit map of the memory 35C, and A (0,0), B (5000,
0), C (0,7000), D (5000,700)
0), that is, x ₁ = y ₁ = 0, x ₂ = 5000, y ₂ =
A resist pattern centering on this position is formed on the transfer belt 10 at the address 7000, and as a result of detection, A '(12, -12), B' (5036, -2
4), C '(12, 7012), D' (5036, 70)
00). (That is, x ₁ '= 12, y ₁ ' = -12,
x ₂ '= 5036, y ₁ "= -24, x ₁ " = 12, y ₂ ' = 7
012, x ₂ "= '5036, y ₂ " 7000) At this time, C ₁ = 5000/5024 = 0.9952,
C ₂ = -12, C ₃ = 0.9966, C ₄ = 12, C ₅
= -0.002389, and x = 0.
9952 x (x'-12), y = 0.9966 x {y '
+ 12-0.002389 x (x'-12)}.

Therefore, the coordinates of the image data Q'are Q '(1
500, 2000), the coordinate Q (x, y) after the coordinate exchange is Q (1481, 200) as shown in FIG.
2).

Actually, by performing the dot position correction by the coordinate conversion in this way, it becomes possible to correctly form the image data at a desired position on the transfer belt 10.

Other colors, that is, M (magenta),
The method of coordinate conversion is exactly the same for Y (yellow) and K (black), and the coefficient C in Formula 3 is calculated for each color.
M _{1 to} M ₅ , Y _{1 to} Y ₅ , K _{1 to} K corresponding to _{1 to} C _5
5 should be calculated and the coordinates converted. Then, by superimposing all the colors after coordinate conversion, it is possible to obtain a full-color image with no color shift. In addition, in calculation of the above-mentioned numerical formula 3 etc., the decimal point was rounded off and the address of each dot was calculated.

In the above description, generation of the registration mark
And data C for coordinate correction₁ ~ C _Five Calculation of etc. is an example
It was done during the pre-rotation as.
It may be performed at any timing that needs correction,
For example, it may be performed each time the printer is powered on.
Also, it may be performed at a predetermined timing using a timer or the like.
Yes. Also in this regard, books that do not require mechanical correction
By using the invention, the correction time can be significantly shortened.
It becomes possible, and as a result, the timing of correction
It is possible to make the reason significantly wider than in the past.

In the above-described first embodiment, the registration marks formed on the transfer belt 63 are read by the CCD sensor portions 14A and 14B downstream of the separation position of the transfer paper P, but as shown in FIG. Unit 61A,
61B and the light sources 62A and 62B may be provided upstream of the separation position of the transfer paper P.

In this case, there is a drawback that the roller 64 is required separately from the transfer roller 11K and the transfer belt 63 is slightly long, but the registration mark is formed on the transfer paper p instead of on the transfer belt 63. The transfer belt 63 does not have to worry about the color tone of the transfer belt.
There is an advantage in that the registration mark is not hindered even if the mark becomes dirty.

Further, in the first embodiment, as shown in FIG. 6, the case where the resist marks A ′, B ′, C ′, D ′ are formed in the main scanning direction and the sub scanning direction in the respective two directions, that is, four in total is formed. As described above, as shown in FIG. 9, by using three sets of CCD units 65A, 65B, and 65C, three registration marks can be detected in the main scanning direction. Of course, two or more registration marks may be provided also in the sub scanning direction. In particular, by dividing the main scanning direction into three, it is possible to more precisely correct the image distortion due to the partial distortion of the lens group 55C of the optical system shown in FIG.

FIG. 10 shows three in the main scanning direction and the sub-scanning method 2.
The figure shows a case where a total of 6 resist marks are formed, where A to F are predetermined positions and A ′ to F ′ are actual resist mark positions. Even in this case, the rectangle A
A'B 'for each of the two areas BED and BCFE
The deviation from E'D 'and B'C'F'E' may be obtained in the same manner as in the first embodiment, and the dot position may be corrected in each area.

The specific method is the same as that of the first embodiment for each area, and the description thereof is omitted.

Further, in the first embodiment, the bit map memories 35C to 35K are provided at the subsequent stage of the coordinate changing means 34, but the bit map memory may not necessarily be used. In particular, generation of image data, for example, the original 4 in FIG.
If the reading speed of 1 is configured to match the processing speed of the image data in the subsequent stage, the image data can be sequentially processed. Therefore, instead of the bitmap memories 35C to 35K,
It is also possible to directly write the data after the coordinate conversion to the line memories 36C to 36K. In this way, memory can be saved significantly.

In general, the distortion of the laser scanning devices 18C to 18K is often greatly affected by the temperature rise state of the printer body. Therefore, prevention of temperature rise is an important problem in a full-color printer using a plurality of photosensitive drums.

By the way, as shown in FIG. 11, a temperature sensor 71 is provided in the vicinity of the optical system, and when the detected temperature value T exceeds a certain value T1 or is less than a certain value T2, each print or a predetermined value is obtained. If the registration correction is performed by coordinate conversion every time, it is possible to prevent such a color shift when the temperature changes.

In the above description, even when each color is printed in a single color, the transfer paper P
It goes without saying that an image with extremely high printing accuracy can be obtained.

Further, in the above-mentioned embodiment, an example in which a dot signal having gradation is used is shown. However, in the case where a dither method is used or higher resolution image data is used, 2
It is needless to say that a sufficient gradation can be obtained even with a value image, and even in such a case, the present invention can be carried out in exactly the same manner. Furthermore, the present invention is similarly effective in a printer using a light source other than laser light, such as an LED or a liquid crystal. [Second Embodiment] FIG. 12 is a schematic cross-sectional view for explaining the structure of a color image forming apparatus showing a second embodiment of the present invention, which is composed of, for example, a 4-drum type color laser beam printer and a color reader 67. Corresponding to the case of the digital copying machine according to the present invention, the same parts as those in FIG. FIG. 13 is a block diagram illustrating the control configuration of the color image forming apparatus shown in FIG. 12, and the same components as those in FIG. 3 are designated by the same reference numerals.

In FIG. 13, a manuscript (original image) 41 consisting of a full-color image is produced by the optical means of the reader section 67 as shown in FIG. 12, and the three primary colors of red (R), green (G), and blue (B). After being decomposed into
It is converted into a multi-valued color signal by R, 42G and 42B.

Reference numeral 61 is a light source, 62 to 64 are reflection mirrors, 6
Reference numeral 5 is a lens, 66 is a spectroscopic device (a dichroic prism, etc.), and 68 is a platen glass. At this time, in order to obtain a good image, the CCD sensors 42R, 42G, 42
The resolution of the optical system including the number of B elements is preferably about 400 to 600 dots / inch or more.

Correspondence between this embodiment and each means of the third invention and its operation will be described below with reference to FIGS. 12 and 13.

A third invention is a reader unit 67 for optically reading an original image and a photoconductor (1C, 1M, 1Y, 1K).
And an exposure unit (laser scanning device 18) for irradiating the photoconductor with a light beam modulated by each color signal to form an electrostatic latent image.
C, 18M, 18Y, 18K), developing means (developing units 7C, 7M, 7Y, 7K) for developing the electrostatic latent image formed on the photoconductor by the exposing means, and the developing means. Image stations ST1 to ST having transfer means for transferring each visualized color image to transfer paper
In the color image forming apparatus, a plurality of 4 are arranged side by side, and the color image formed by each of the image stations ST1 to ST4 is sequentially transferred to the transfer material conveyed by the conveying means to form a color image. First test mode processing means 101A for printing a registration mark having a predetermined pattern having reference coordinates on the transfer paper in each of the image stations ST1 to ST4 of the printer section 27, and the first test mode processing means 1
Second test mode processing means 10 for reading the registration mark formed on the transfer material by 01A from the reader unit 67 and detecting the coordinates of the formation position of the registration mark.
1B, and the output coordinate position of the image data for each color is misregistered based on the amount of misalignment determined from the registration mark formation position coordinates detected by the second test mode processing means and the predetermined reference coordinates. A first test mode in which a registration mark having a predetermined pattern having reference coordinates in each image station of the printer unit 27 is printed on the transfer paper. When the registration mark formed on the transfer material by the processing means is read from the reader 67 and the second test mode processing means 101B detects the formation position coordinates of the registration mark, the detected formation position of the registration mark. The coordinate conversion means 10 based on the amount of deviation determined from the coordinates and predetermined reference coordinates. C automatically converts the output coordinate position of the image data of each color into the output coordinate position in which the registration deviation is corrected, expands the converted image data of each color in the storage means, and based on the expanded image data Each exposure means of each image station exposes the modulated light beam on each photoconductor, and even if a registration deviation due to a mechanical arrangement deviation of the optical scanning system occurs in each image station, The registration mark image output from the printer unit is read by the reader unit, and each color image is output by each image station at a position that cancels the registration deviation, so that it is possible to output a color image without color deviation at high speed. .

Next, the CCD sensor 42R, shown in FIG.
The analog outputs of 42G and 42B are A / D converter 4
It is converted into a digital value according to the luminance by 3R, 43G, and 43B.

At this time, in order to obtain a good image, 64 to 2
A gradation level of 56 gradations or more is preferable. The brightness data thus obtained is used as a shading correction circuit 44 for correcting variations in the optical system and CCD elements.
Gamma conversion units 45R, 45 via R, 44G, 44B
The red, green, and blue of the luminance data are converted into corresponding complementary colors of cyan (C ′), magenta (M ′), and yellow (Y ′) by G and 45B (that is, inverse logarithmic conversion). And C ', obtained in this way,
Black (K ') data is extracted from the M'and Y'data by the black data generation circuit 46. Although various methods are used for this, as an example, a method of setting the minimum value of C ′, M ′, Y ′ as black data can be used. Using the C ′, M ′, Y ′, and K ′ image data thus obtained, the masking processing circuit 47 performs the above-described lower masking.

Next, in order to match the C ″, M ″, Y ″, and K ″ image data generated by the masking process with the tone characteristics of the printer, gamma conversion units 48C, 48M, 48.
Gradation correction is performed with Y and 48K. A method of printing the image data C, M, Y, K obtained in this way will be described below.

In FIG. 13, the image signals C, M, Y, and K having gradation are first subjected to coordinate conversion described later, and then 256.
The gradation density signal is supplied to the pulse width modulation circuits 37C, 37M, 3
The pulse width is modulated by 7Y and 37K to correspond to the laser ON time, and then the laser scanning devices 18C and 18
Input to M, 18Y and 18K. Laser scanning device 18
The structure of C, 18M, 18Y and 18K is similar to that of FIG.

Next, in the color image forming apparatus as described above, a method and apparatus for preventing C, M, Y and K color shifts will be described.

First, prior to the actual printing, the test mode described below is executed.

In FIG. 12, the display on the reader 67 is
The test mode is input on the operation unit 33. At this time, it is convenient to display a necessary message (for example, setting a paper of a predetermined size in the cassette) on the display / operation unit 33 according to the input of the test mode key.

In this embodiment, the test mode is divided into the mode 1 and the mode 2, and the test mode 1 is a series of modes executed at the same time as the test mode key input, and the respective parts operate at the timings shown in FIG.

FIG. 14 is a timing chart for explaining the processing operation of test mode 1 in the color image forming apparatus shown in FIG.

As shown in this figure, first, the printer drive system 72 starts its operation, and waits until printing is possible, and then the transfer paper P is fed from the cassette 26. Next, the registration marks 81 to 85, which are built in the memory of the microcomputer 101 as shown in FIG.
Photosensitive drums 1C, M, Y, K corresponding to coordinates on Y, K
Printed on top. These are sequentially transferred onto the transfer paper P, and the test print 86 of FIG. 15 is obtained.

In the present embodiment, for the sake of explanation, four registration marks 82, 83, 8 relating to cyan image data are used.
The coordinates on the bit map memory 35C corresponding to 4, 85 (that is, corresponding to the central portion of the registration mark 81, for example) are A (x ₁ , y ₁ ), B (x
₂ , y ₁ ), C (x ₁ , y ₂ ), D (x ₂ , y ₂ ).

The test mode 1 is ended by the output of the test print 86, and then the test mode 2 is executed. In the test mode 2, the test print 86 is set at a predetermined position on the platen glass 68 of the reader 67, and the registration marks 82 to 85 are read.

Therefore, it is convenient to display a necessary message (for example, an instruction to set a test print and press the copy button) on the display / operation unit 102 at the same time as the end of the test mode 1.

FIG. 16 is a timing chart for explaining the processing operation of the test mode 2 in the color image forming apparatus shown in FIG.

As shown in this figure, first, by inputting a copy button or the like, the reader driving system (61 to 64 in FIG. 1) advances, and the registration marks 82 to 85 on the test print 86 shown in FIG. Read. This image information is subjected to data processing up to the gamma conversion units 48C, 48M, 48Y and 48K as the gradation correction means shown in FIG. At, the coordinates corresponding to each registration mark are detected. This is, for example, the coordinates corresponding to the central portion of the registration mark 81 as described above, and can be known by detecting the edge portion of each registration mark.

In the present embodiment, for the sake of explanation, regarding the registration mark of the cyan image, A ′ (x ₁ ',
y ₁ '), B' (x ₂ ', y ₁ "), C' (x ₁ ", y ₂ '),
D '(x ₂ ", y ₂ "). These relationships are shown in FIG.

The test mode 2 is then ended by returning the reader driving system 71 to a predetermined position after calculating the coordinate conversion system number, which will be described below.

Next, a method of coordinate conversion will be described.

First, when the laser optical system of the printer unit 27 and the optical system of the reader unit 67 have no deviation, the cyan registration mark coordinates A, B, C, D and A ', B',
C'and D'should exactly match. Actually, due to the inclination of the reflection mirror 57C, the deviation of the focal length of the laser optical system 18C, the positional deviation of the photosensitive drum unit 9C, the positional deviation of the optical systems 61 to 65 of the reader unit and the CCD unit 42R, etc. , D and A ', B', C ',
A shift occurs in D '. (Refer to FIG. 6)
It is defined as shown in Formula 2 in the embodiment, and further calculated as shown in Formula 3.

The C1 to C5 thus obtained are stored in the memory in the microcomputer 34. This completes the test print mode.

[0107] Then, in the normal print mode, the correction coefficient M ₁ ~M ₅ magenta obtained in the same manner as the correction coefficient C ₁ -C ₅ and which of the cyan, the correction coefficient of the yellow Y ₁ to Y ₅ , Using the black correction factors K _{1 to} K ₅ ,
In the microcomputer 101, the coordinates of the image data C, M, Y, and K are sequentially converted based on the mathematical expression 3 in the first embodiment, and the bitmap memories 35C, 35M, and 35 are used.
If they are stored in Y, 35K, read out at a predetermined timing and printed on the photosensitive drums 1C, M, Y, K, the respective colors are superposed well on the transfer paper P, and an image without color misregistration can be obtained. It becomes a possible city.

Moreover, the printing accuracy can be significantly improved because the position of the dot image on the transfer paper P can be brought close to the true coordinates.

Furthermore, the optical systems 61 to 66 on the reader side,
Even if the CCD sensors 42R, 42G, 42B, etc. are tilted or have a deviation in magnification or the like, they can be simultaneously corrected by implementing the present invention. For example, the x and y coordinates are associated with the bitmap of the memory 35C, and A (0,0), B (5000,
0), C (0,7000), D (5000,7000)
That is, x ₁ = y ₁ = 0, x ₂ = 5000, y ₂ = 7
A resist pattern centered on this position was formed on the transfer belt as the address 000, and as a result of detecting this,
A '(12, -12), B' (5036, -24),
C '(12,7012), D' (5036,7000)
Met.

That is, x ₁ '= 12, y ₁ ' = -12, x
_{2 '= 5036, y "=} 24, x 1" = 12, y 2' = 701
2, x ₂ "= 5036, y ₂ " = 7000, C _{1 to} C
_{When 5} is calculated according to the above formula 3, C ₁ = 5000/5
024 = 0.9952, C ₂ , C ₃ = 0.99666, C ₄
= 12, C ₅ = −0.002389, and x = 0.99952 × (x′−1) according to Formula 3 in the first embodiment.
2), y = 0.9966 * {y '+ 12-0.0023
89 × (x′-12)}. Therefore, when the coordinates of the image data Q ′ are Q ′ (1500, 2000), the coordinates Q (x, y) after the coordinate conversion becomes Q (1481, 2002) as shown in FIG. 7.

As a result of actually printing after the coordinate conversion, the image data could be correctly formed at the desired position on the transfer paper P.

In the present embodiment, in the calculation of the above-mentioned formula 3, etc., the decimal point and below are rounded off to calculate the address of each dot.

Further, the bit map memories 35C and 35
The sizes of M, 35Y, and 35K are larger than the maximum printable image data. Further, the image data is based on a basic clock (not shown) of the image processing control system, and the beam detectors 56C, M, Y, K (see FIG. 4).
However, M, Y and K are laser beams 2 to the photosensitive drums 1C, M, Y and K in synchronism with the BD signal from (not shown).
The write timing by 8C, 28M, 28Y, 28K was determined.

In the above-described second embodiment, the registration marks 82 to 85 in the test mode 1 are generated by preparing bit data in the memory of the microcomputer 101, but a test chart such as the test print 86 is used. It is possible to prepare in advance and read the coordinates of the registration mark on the test chart in the test mode 1.

The coordinates at this time are the coordinates A of the first embodiment,
Corresponding to B, C and D, A (x ₁ , y ₁ ), B (x ₂ ,
y ₂ ), C (x ₃ , y ₃ ), and D (x ₄ , y ₄ ).
Here, in the test mode 1, the microcomputer 10
In the case of 1, the coordinates are not converted, and the printer is used as it is for the above A,
B, C and D are printed, and in this test print, the test mode 2 is executed in the same procedure as in the second embodiment.

At this time, the coordinates of the test print read in the test mode 2 are A '(x ₁ ', y ₁ '), B'.
_{(X 2 ', y 2'} ), C '(x 3', y 3 '), D' (x 4 ', y
₄ '), the relation between the coordinates Q (x, y) on the bitmap and the actual coordinates Q' (x ', y') is x = f
It can be obtained by solving (x ', y'), y = g (x ', y'). However, the functions f and g are x ₁ , x ₂ , and
_{x 3, x 4, x 1} ', x 2', x 3 ', x 4', y 1, y 2, y
It is defined by ₃ , y ₄ , y ₁ ′, y ₂ ′, y ₃ ′, y ₄ ′.
In this case, since it is possible to independently know the optical system accuracy of each of the reader unit 67 and the printer unit 27 from the test mode 1 and the test mode 2, the coordinates (that is, the true coordinates) of the test chart are set in advance in the micro. If it is registered in the memory of the computer 34, this and A, B, C, D
By comparing the coordinates of A ′, B ′, C ′, and D ′ with each other, it is possible to detect the status of the reader unit and the printer unit and perform self-diagnosis.

In the above-described second embodiment, as shown in FIG. 15, a case where two registration marks A ′, B ′, C ′ and D ′ are formed in the main scanning direction and the sub scanning direction, that is, a total of four registration marks are described. The test print 9 was performed as shown in FIG.
By forming the resist marks 91 to 96 on the No. 7, three resist marks can be detected in the main scanning direction.
Of course, two or more registration marks may be provided also in the sub scanning direction. In particular, by dividing the main scanning direction into three, it becomes possible to more precisely correct the image distortion due to the partial distortion of the lens group 55C and the like of the optical system shown in FIG.

Further, as shown in FIG. 10, the main scanning direction 3
In the case of showing the relationship between the true coordinates and the real image when a total of six registration marks, that is, two registration marks in the sub-scanning direction, are formed,
F is a predetermined position and A ′ to F ′ are actual registration mark positions to be printed. Even in this case, the rectangle A
A'for each of the two areas of BED and BCFE
The deviations from B'E'D 'and B'C'F'E' may be obtained in the same manner as in the first or second embodiment, and the dot position may be corrected in each area. The specific method for each area is the same as that of the first or second embodiment, and the description thereof is omitted.

In the above description, it goes without saying that even when each color is printed in a single color, an image with extremely high printing accuracy on the transfer paper P can be obtained by using the present invention.

Further, in the above-described embodiment, an example in which a dot signal having a gradation is used is shown. However, even when a dither method is used or a higher resolution image data is used, even a binary image is used. It is needless to say that sufficient gradation can be obtained, and even in such a case, the present invention can be carried out in exactly the same manner.

Furthermore, the present invention provides a light source other than laser light,
For example, an image forming apparatus using an LED, a liquid crystal or the like is also effective.

[0122]

As described above, the first aspect of the present invention
According to the invention, the forming coordinate information of each pattern generated by the coordinate data generating means for generating the forming coordinate information of each pattern transferred to the carrying means from each test pattern image information read by the reading means and a predetermined reference. The coordinate conversion means automatically converts the output coordinate position of the image data of each color into the output coordinate position in which the registration shift is corrected based on the shift amount determined from the position information, and the converted image data of each color is stored. Means, and each exposure means of each image station exposes a light beam modulated based on the developed image data onto each photoconductor,
Even if registration error due to mechanical displacement of the optical scanning system occurs in each image station, each image station outputs each color image at a position that cancels the registration error, so that there is no color deviation. Images can be output at high speed.

According to the second aspect of the invention, the reading means forms the test pattern image formed at each image station based on the test pattern data of each color read from the storage means and transferred to the transfer material on the conveying means. Since it is read, it is possible to accurately detect the registration deviation amount of each image station.

According to the third aspect of the invention, in each image station of the printer section, a registration mark having a predetermined pattern having reference coordinates is formed on the transfer material by the first test mode processing means for printing on the transfer paper. When the second test mode processing means detects the registration position coordinates of the registration mark by reading the registration mark from the reader unit, it is determined from the detected registration position coordinates of the registration mark and predetermined reference coordinates. The coordinate conversion means automatically converts the output coordinate position of the image data for each color into the output coordinate position in which the registration deviation is corrected based on the deviation amount, expands the converted image data of each color in the storage means, and expands it. A light beam modulated on the basis of the recorded image data is individually projected onto each photoreceptor by each exposure means of each image station. Since the exposure is performed, even if registration misalignment due to mechanical misalignment of the optical scanning system occurs in each image station, the registration mark image output from the printer is read by the reader to cancel the registration misalignment. Since each image station outputs each color image to the position to be turned on, it is possible to output a color image without color shift at high speed.

Therefore, there is an effect that a color image in which the registration deviation of each image station is corrected can be output at high speed by signal processing without mechanically correcting the scanning position deviation of the optical scanning system.

[Brief description of drawings]

FIG. 1 is a schematic sectional view illustrating the configuration of a color image forming apparatus showing a first embodiment of the invention.

FIG. 2 is a block diagram illustrating a configuration of a registration correction circuit of the color image forming apparatus shown in FIG.

3 is a block diagram illustrating a data processing configuration when a color document reading device is connected to the color image forming apparatus illustrated in FIG.

FIG. 4 is a schematic diagram illustrating the configuration of the laser scanning device shown in FIG.

FIG. 5 is a diagram showing an example of registration marks for detecting registration deviation correction in the color image forming apparatus according to the present invention.

FIG. 6 is a diagram illustrating a registration deviation correction principle in the color image forming apparatus according to the present invention.

FIG. 7 is a diagram illustrating a registration deviation correction principle in the color image forming apparatus according to the present invention.

FIG. 8 is a sectional view of an essential part for explaining another registration mark reading mechanism in the color image forming apparatus according to the present invention.

FIG. 9 is a perspective view of a principal part for explaining another registration mark reading mechanism in the color image forming apparatus according to the present invention.

FIG. 10 is a diagram illustrating a registration deviation correction principle in the color image forming apparatus according to the present invention.

FIG. 11 is a schematic sectional view illustrating another configuration of the color image forming apparatus showing the first embodiment of the present invention.

FIG. 12 is a schematic sectional view illustrating the configuration of a color image forming apparatus showing a second embodiment of the present invention.

13 is a block diagram illustrating a control configuration of the color image forming apparatus illustrated in FIG.

FIG. 14 is a timing chart for explaining the processing operation of test mode 1 in the color image forming apparatus shown in FIG.

15 is a diagram showing an example of registration marks for detecting registration deviation in the color image forming apparatus shown in FIG.

16 is a timing chart for explaining the processing operation in test mode 2 in the color image forming apparatus shown in FIG.

FIG. 17 is a diagram illustrating another registration mark formation state in the color image forming apparatus according to the second embodiment of the present invention.

[Explanation of symbols]

 14A CCD sensor section 14B CCD sensor section 32 Test pattern generating means 33 Coordinate data generating means 34 Coordinate converting means 35 Bit map memory

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03G 15/04 111 21/14 H04N 1/60 1/46 H04N 1/40 D 1/46 Z

Claims (3)

[Claims] 1. A photoconductor, an exposure unit for irradiating the photoconductor with a light beam modulated by each color signal to form an electrostatic latent image, and an electrostatic unit formed on the photoconductor by the exposure unit. A plurality of image stations each having a developing unit that visualizes a latent image and a transfer unit that transfers each color image visualized by the developing unit to a transfer paper are juxtaposed, and the color formed by each image station. In a color image forming apparatus that forms a color image by sequentially transferring images to a transfer material that is conveyed by a conveying unit, a test pattern generating unit that generates test pattern data for detecting a predetermined registration deviation, and a test pattern generating unit. Storage means for storing the test pattern data of each color generated by the pattern generation means,
From the reading means for reading the test pattern image formed on each image station and transferred onto the conveying means based on the test pattern data of each color read from the storage means, and the test pattern image information read by the reading means. Coordinate data generating means for generating the forming coordinate information of each pattern transferred to the conveying means, and a deviation amount determined from the forming coordinate information of each pattern generated by the coordinate data generating means and predetermined reference position information. Coordinate conversion means for automatically converting the output coordinate position of the image data for each color into the output coordinate position in which the registration deviation has been corrected, and the image data of each color converted by this coordinate conversion means is expanded in the storage means. Then, the light beam modulated based on the developed image data is exposed to each exposure station of each image station. There the color image forming apparatus characterized by being configured to expose respectively on each photosensitive member. 2. The reading means reads the test pattern image formed in each image station and transferred to the transfer material on the conveying means based on the test pattern data of each color read from the storage means. The color image forming apparatus according to claim 1. 3. A reader unit for optically reading an original image, a photoconductor, and a light beam modulated by each color signal based on each color image information output from the reader unit is irradiated to the photoconductor to electrostatic latent image. Exposure means for forming an image, developing means for developing the electrostatic latent image formed on the photoconductor by the exposure means, and each color image visualized by the developing means for transferring to a transfer paper. A color image forming apparatus including a plurality of image stations having transfer means arranged side by side, and a printer section for forming a color image by sequentially transferring color images formed by the respective image stations onto a transfer material conveyed by a conveying means. A first test mode processing means for printing a registration mark having a predetermined pattern having reference coordinates at each image station of the printer section on the transfer paper. Second test mode processing means for reading the registration mark formed on the transfer material by the first test mode processing means from the reader part to detect the coordinates of the formation position of the registration mark, and the second test mode processing means.
The output coordinate position of the image data of each color is corrected based on the shift amount determined from the registration mark forming position coordinate detected by the test mode processing means and the predetermined reference coordinate. And a coordinate conversion means for automatically converting the image data of each color converted by the coordinate conversion means into a storage means,
A color image forming apparatus, wherein each exposure means of each image station exposes a light beam modulated based on the developed image data onto each photoconductor.