JP2000035704A - Image forming device and color-slippage correction method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high-quality multicolor image by automatically adjusting, in a simple structure, color slippage by mechanical accuracy and so on. SOLUTION: In the color slippage correction method, a main control CPU 201 controls image formation so that a first pattern is formed in a specific color onto an image carrier and a second pattern, different from the first pattern, is formed in other color, different from the specific color, onto the image carrier while superimposed onto the first pattern. From the pattern of a composite of the first and second patterns formed one on the other on the image carrier, a density detection sensor detects an amount of the slippage of the image in the specific color and the image in the other color from each other. Based on the detected amount of the slippage, the main control CPU 201 controls the image forming position of the image in the other color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming a multi-color image by superimposing respective color images formed in different colors on an image carrier, and a method of correcting a color shift of the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic color image forming apparatus in which a toner color image is formed on an intermediate transfer member and the formed toner color image is transferred to a printing medium, color shift due to mechanical accuracy or the like is adjusted. At the factory, a color misregistration correction pattern was printed, and the degree of color misregistration was judged based on the pattern, and the engine was manually adjusted only once.

[0003]

However, there is a problem that it takes an excessive amount of labor and time for a person to make adjustments one by one in a factory.

Although the amount of color misregistration may change due to replacement of parts or the like after shipment, since it is a delicate adjustment work, there is a problem that a service person cannot make adjustments during a periodic inspection. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the first to tenth inventions according to the present invention is to form a plurality of color images formed in different colors. In an image forming apparatus for sequentially forming a multicolor image on a carrier, a first color formed of a predetermined color is formed on the image carrier.
And an image in the predetermined color from a composite pattern of a second pattern different from the first pattern, which is formed by another color different from the predetermined color and overlapped with the first pattern. By detecting the amount of deviation from the image of another color and controlling the image forming position of the other color image based on the detected amount of deviation, a simple configuration allows color deviation due to mechanical accuracy or the like. An object of the present invention is to provide an image forming apparatus capable of forming a high-quality multi-color image by performing automatic adjustment and a color misregistration correction method for the image forming apparatus.

[0006]

According to a first aspect of the present invention, a plurality of color images formed of different colors (yellow (Y), magenta (M), cyan (C), and black (B)) are provided. Are sequentially superimposed on an image carrier (the intermediate transfer member 9 shown in FIG. 1) to form a multicolor image in a first pattern (a reference color shown in FIG. 11) in a predetermined color (magenta (M)). Forming a pattern 1101) on the image carrier;
A second pattern different from the first pattern by another color (yellow (Y), cyan (C), black (B)) different from the predetermined color, overlapping the first pattern to be formed. (First to third color shift patterns 1 shown in FIG. 11)
102, 1104, and 1106) on the image bearing member (the main control CPU 201 shown in FIG. 3 controls image formation based on a program stored in a ROM 201a). Detecting means for detecting the amount of deviation between the image of the predetermined color and the image of the other color from a composite pattern of the first and second patterns formed on the image carrier (the density detection shown in FIG. 1); The sensor 9c measures the reflection density of the developer on the intermediate transfer member 9, and the main control CPU 201 shown in FIG.
M201a) and second control means (FIG. 3) for controlling the image forming position of the image of the other color based on the amount of deviation detected by the detection means. The main control CPU 201 controls the image forming position based on a program stored in the ROM 201a).

According to a second aspect of the present invention, the detecting means (density detecting sensor 9c shown in FIG. 1) optically measures the reflected light of the image formed on the image carrier to obtain an image density. The second control means (the main control CPU 201 shown in FIG. 3 controls the density based on a program stored in the ROM 201a) is based on the image density detected by the detection means. This is for controlling the image forming density.

[0008] A third invention according to the present invention comprises a storage means (RAM 201b shown in FIG. 3) for storing a shift amount between the image of the predetermined color and the image of the other color detected by the detection means. It is provided.

In a fourth aspect according to the present invention, the storage means includes a nonvolatile storage means (NVRAM, EE not shown).
PROM, a nonvolatile memory card such as a nonvolatile memory card).

According to a fifth aspect of the present invention, the first pattern (reference pattern 1101 shown in FIG. 11) includes a predetermined number of lines extending in the main scanning direction at a first interval in the sub-scanning direction. The arranged blocks (the line pattern blocks 501 shown in FIG. 5) are arranged in the sub-scanning direction at the first interval (5
The second pattern (the first to third color shift patterns 110 shown in FIG. 11)
2, 1104, 1106) are a predetermined number of the blocks arranged in the sub-scanning direction at a second interval (6 dots) different from the first interval.

In a sixth aspect according to the present invention, the second interval is wider by one pixel in the sub-scanning direction than the first interval.

A seventh invention according to the present invention provides an information processing apparatus (not shown) via a predetermined communication medium (not shown).
The image is formed based on the print information input from the printer.

According to an eighth aspect of the present invention, an image is formed based on a multicolor original image read from an original.

According to a ninth aspect of the present invention, the first control means is instructed to form the first and second patterns, and the first control means is provided with the first control means.
Instruction means (operation panel (not shown)) for instructing detection of a shift amount between the image of the predetermined color and the image of the other color from the composite pattern of the second pattern and the second pattern
Is provided.

According to a tenth aspect of the present invention, there is provided a color misregistration correcting method for an image forming apparatus for forming a multicolor image by superimposing images of different colors formed on different colors on an image carrier. A first pattern forming step of forming one pattern on the image carrier (step (1) in FIG. 12);
A second color different from the first pattern by another color different from the predetermined color over the first pattern to be formed.
A second pattern forming step (steps (2) to (4) in FIG. 12) of forming the above pattern on the image carrier, and first and second patterns formed so as to overlap on the image carrier. A detecting step of detecting a shift amount between the image of the predetermined color and the image of the other color from the composite pattern of FIG.
(5)) and an image forming step (steps (1) to (13) in FIG. 13) of forming the other color image at a position based on the shift amount.

[0016]

[First Embodiment] FIG. 1 is a sectional view showing a configuration of a laser beam printer to which an image forming apparatus according to a first embodiment of the present invention can be applied.

In FIG. 1, reference numeral 30 denotes a scanner unit which irradiates image light based on an image signal supplied from an information processing apparatus via a predetermined communication medium to a photosensitive drum (image carrier) 15
Is selectively exposed to form an electrostatic latent image. A polygon mirror 31 deflects image light emitted by a laser diode (not shown) and scans the photosensitive drum 15 rotated at a constant speed by a drive motor (not shown) via an imaging lens 32 and a reflection mirror 33. I do. 31
Reference numeral a denotes a scanner motor which drives the polygon mirror 31 to rotate. The scanner unit 30 includes a polygon mirror 31,
It comprises a laser diode (not shown), an imaging lens 32, a reflection mirror 33, a scanner motor 31a, and the like.

That is, when an image signal is supplied to a laser diode (not shown), the scanner unit 30 irradiates the polygon mirror 31 with image light corresponding to the image signal. The polygon mirror 31 is rotated at high speed by a scanning motor 31a, and the image light reflected by the polygon mirror 31 selectively exposes the surface of the photosensitive drum 15 rotating at a constant speed via the imaging lens 32 and the reflection mirror 33. To form an electrostatic latent image.

Reference numeral 13 denotes a drum unit, which is detachably supported by the printer main body, and is configured such that the unit can be easily replaced in accordance with the life of the photosensitive drum 15. 16
Reference numeral denotes a cleaning blade, which is a waste toner after transferring a visible image formed by the toner on the photosensitive drum 15 to the intermediate transfer member 9, or a four-color visible image formed on the intermediate transfer member 9. After the transfer to the printer, the waste toner is cleaned (removed). Reference numeral 14 denotes a cleaner container, and the photosensitive drum 1 cleaned (removed) by the cleaning blade 16.
5 is stored in the storage unit 14a. Reference numeral 101 denotes a sensor that detects the amount of waste toner stored in the storage unit 14a in the cleaner container 14.

The cleaner container 14 contains the photosensitive drum 1.
5 is rotatably supported. The drum unit 13
In FIG. 1, a photosensitive drum (photoconductor) 15 and a cleaner container 14 also serving as a holder for the photosensitive drum 15 are integrally formed. The photosensitive drum 15 is formed by applying an organic photoconductor layer on the outer periphery of an aluminum cylinder, and is rotatably supported by the cleaner container 14. Further, the photosensitive drum 15 rotates by transmitting a driving force of a drive motor (not shown). The drive motor rotates the photosensitive drum 15 in a counterclockwise direction (the direction of the arrow in the figure) in accordance with the image forming operation. A contact charging roller 17 uniformly charges the photosensitive drum 15 as primary charging means.

20Y, 20M and 20C are yellow (Y)
In order to visualize the electrostatic latent image on the photosensitive drum 15 with three color developing units, a developing unit, a magenta (M) developing unit, and a cyan (C) developing unit, yellow (Y) and magenta (M) ) And cyan (C) development. A black (B) developing unit 21B develops the electrostatic latent image on the photosensitive drum 15 into black (B).

Reference numeral 21BS denotes a sleeve which is arranged at a minute interval of, for example, about 300 μm with respect to the photosensitive drum 15 and rotates clockwise. Reference numeral 21BB denotes an application blade, which is pressed against the outer periphery of the sleeve 21BS to form a sleeve 21B.
A black developer is applied to the outer periphery of S.

That is, the black developing unit 21B transports the toner by a feeding member built in the black developing unit 21B, and also charges the toner by frictional charging so that the toner is applied to the outer periphery of the sleeve 21BS rotating clockwise by the application blade 21BB. Is given. Also, the sleeve 21
By applying a developing bias to the BS, development is performed on the photosensitive drum 15 in accordance with the electrostatic latent image, and a visible image is formed on the photosensitive drum 15 using black toner.

Reference numerals 20YS, 20MS, and 20CS denote sleeves that rotate with the rotation of the developing rotary 23, and the predetermined sleeves 20YS, 20MS, and 20CS are used as photosensitive sleeves 15 and 20CS.
With a small interval of about 300 μm. Thereby, the predetermined color developing devices 20Y, 20
M and 20C stop at the phenomenon position facing the photosensitive drum 15, and a visible image is created on the photosensitive drum 15. 20Y
B, 20MB, 20CB are coating blades, 20YB, 2
0MB, 20CB coating roller, each sleeve 20
YS, 20MS, 20CS
Each color developer is applied to the outer periphery of 0YS, 20MS, and 20CS.

The black developing device 21B is detachably attached to the printer main body, and the color developing devices 20Y, 20M and 20C are detachably attached to a developing rotary 23 which rotates about a rotation shaft 22. ing.

When a color image is formed, the developing rotary 23 rotates for each rotation of the intermediate transfer member 9 and the yellow developing device 20 rotates.
The developing process is performed in the order of Y, magenta developing device 20M, cyan developing device 20C, and then black developing device 20B, and the intermediate transfer member 9 rotates four times to produce yellow (Y), magenta (M), cyan (C), and black. A visible image is sequentially formed by each toner of (B), and as a result, a full-color visible image is formed on the intermediate transfer member 9.

A transfer material cassette 1 stores a transfer material 2. A paper feed roller 3 feeds the transfer materials 2 stored in the transfer material cassette 1 one by one. 4 to 7 are conveying rollers,
The transfer material 2 fed by the feed roller 3 is transported. 8
Is a registration roller for temporarily stopping the transfer material 2 transported by the transport roller 7 and adjusting the leading edge of the image and the image transfer start position of the transfer material.

The intermediate transfer member 9 is configured to rotate in accordance with the rotation of the photosensitive drum 15 in contact with the photosensitive drum 15, and rotates clockwise during color image formation.
The photosensitive drum 15 receives four multiple transfers of the visible image. Further, the intermediate transfer body 9 simultaneously transfers the color visible image on the intermediate transfer body 9 to the transfer material 2 by multiple transfer by nipping and transporting the transfer material 2 by contacting a transfer roller 10 described later during image formation. The transfer roller 10 is provided as a transfer charger that is supported so as to be able to contact and separate from the photosensitive drum 15, and is configured by winding a metal shaft with a medium-resistance foam elastic body.

The transfer roller 10 is separated downward so as not to disturb the color visible image during the multiple transfer of the color visible image onto the intermediate transfer body 9 as shown by a solid line in FIG. After the four color visible images have been formed on the intermediate transfer member 9, the transfer roller 10 is moved by a cam member (not shown) by a dotted line as shown in FIG. Shown above.
As a result, the transfer roller 10 is pressed against the intermediate transfer member 9 with a predetermined pressing force via the transfer material 2, and a bias voltage is applied to transfer the color visible image on the intermediate transfer member 9 to the transfer material 2.

A fixing unit 25 fixes the transferred color visible image while conveying the transfer material 2. A fixing roller 26 heats the transfer material 2. A pressure roller 27 presses the transfer material 2 against the fixing roller 26. The fixing roller 26 and the pressure roller 27 are formed in a hollow shape. Heaters 28 and 29 are built in the fixing roller 26 and the pressure roller 27, respectively, and heat the fixing roller 26 and the pressure roller 27. That is, the fixing roller 26 and the pressure roller 27 transport the transfer material 2 holding the color visible image, and fix the toner on the surface of the transfer material by applying heat and pressure. Reference numerals 34, 35, and 36 denote discharge rollers, which discharge the transfer material 2 after fixing the visible image to a discharge unit 37.

A density sensor 38 detects the density of a permanent image fixed on the transfer material 2. An image formation start position detection sensor 9a detects an image formation timing in the sub-scanning direction. Reference numeral 9b denotes a paper feed start timing sensor which detects a paper feed timing according to the image forming timing. A density sensor 9c detects the density of the toner image developed on the intermediate transfer member 9. The sensors 9a, 9b, 9c are provided around the intermediate transfer body 9.

As described above, the laser beam printer is
An electrostatic latent image is formed on the photosensitive drum 15 by image light formed by a laser diode (not shown) based on an image signal, and a visible image obtained by developing the electrostatic latent image by each of the color developing units 20Y, 20M, 20C, and 21B is formed. The color visible image is formed by multiple transfer onto the intermediate transfer member 9, the color visible image is transferred to the transfer material 2, and the color visible image on the transfer material 2 is fixed by the fixing device 25. .

The laser beam printer is provided with a color reader unit capable of reading a color original image from the original, and the scanner unit 30 irradiates the photosensitive drum 15 with image light based on the original image read by the color reader unit. The image forming apparatus may be a copying machine that forms an image by performing the above operation.

FIG. 2 is a block diagram showing a schematic configuration of an engine unit of the image forming apparatus according to the present invention.

In FIG. 1, reference numeral 200 denotes a video I / F, which is an interface with an external controller for controlling an engine. Reference numeral 207 denotes a sensor unit, which is a temperature / humidity sensor (not shown), a remaining toner detection sensor, an image formation start position detection sensor 9a shown in FIG.
b, the density sensor 9c and the like. A fixing unit 206 includes the fixing unit 25. An image processing gate array (GA) 209 performs γ correction and the like on image data received from the video I / F 200. An image forming unit 208 outputs an image using a laser output, a scanner motor, or the like.

Reference numeral 203a denotes a drive unit, which includes a motor, a clutch,
Driving a fan etc. Reference numeral 203b denotes a sensor unit that performs position detection and the like using a paper feed sensor (not shown) or the like. Reference numeral 204 denotes a paper feed control unit that controls paper feed of the transfer material 2. Reference numeral 205 denotes a high-voltage control unit that controls a high-voltage for development. 202 is a mechanical control CP
U controls the drive unit 203a, the sensor unit 203b, the paper feed control unit 204, and the high voltage control unit 205, respectively. 201
Is a main control CPU that executes a program stored in the ROM 201a and executes a mechanical control CP as a sub CPU.
The U202 and the entire engine unit are totally controlled. 20
Reference numeral 1b denotes a RAM, which is a work area for the main control CPU 201, and also includes a developer 2 to a developer
Can be stored individually.

FIG. 3 is a sectional view for explaining the structure of the intermediate transfer member 9 shown in FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals.

In the figure, an intermediate transfer member 9 is obtained by covering the outer periphery of an aluminum cylinder 12 with an elastic layer 11 of a medium resistance sponge or a medium resistance rubber. Around the intermediate transfer member 9, an image formation start position detection sensor (hereinafter, referred to as a "TOP sensor") 9a, a paper feed start timing sensor (hereinafter, referred to as an "RS sensor") 9b, and a density sensor 9c are provided.

The density sensor 9c forms a developer image for each color density detection on the intermediate transfer member 9 in order to obtain a correct color tone, and uses the density detection result as an exposure amount, a developing bias, or the like. The image forming conditions are fed back to form an original color image and density control is performed to obtain a stable image.

Conventionally, DMAX control, H
There is an alf_Tone control or the like, and the DMAX control creates a developer image on a trial basis with a constant exposure amount and a variable developing high voltage. The density of the developer image is measured, and a development high voltage value corresponding to the target density of each color is calculated. Half_To
In the ne control, the developing high voltage value calculated by the DMAX control is fixed, and the controller varies the exposure amount in several steps to experimentally create a developer image. The developer image is measured and returned to the controller as it is. It is also used when measuring a color shift described later.

FIG. 4 is a block diagram showing the configuration of the image density detection control unit of the image forming apparatus according to the present invention.
The same components as those in FIG. 3 are denoted by the same reference numerals.

In the figure, reference numeral 400 denotes an infrared light emitting unit which irradiates infrared light (hereinafter referred to as light source light) Io to the surface of the intermediate transfer member 9. Reference numeral 401 denotes an infrared light receiving unit;
The reflected light Ir of the light source light Io emitted from 0 on the surface of the intermediate transfer member 9 is received and measured. Reference numeral 403 denotes an LED light amount control unit that monitors the opposite light 406 measured by the infrared light receiving unit 401 and sends it to the main control CPU 201, and controls the amount of infrared irradiation by the infrared light emitting unit 400 based on the light amount control signal 405. The main control CPU 201 performs density calculation and development bias voltage control based on the measured values of the light source light Io and the reflected light Ir.

Hereinafter, a method of detecting the amount of color misregistration of the image forming apparatus according to the present invention will be described.

Reference color (hereinafter referred to as "reference color")
And an image serving as a reference (hereinafter, referred to as a “reference pattern”) is formed on the intermediate transfer body 9. For each color other than the reference color, a developer image for detecting a color shift (hereinafter, referred to as a “color shift pattern”) is formed on the intermediate transfer body 9, and a shift amount (dot) from the reference pattern is detected. In the present embodiment, color misregistration of yellow, cyan, and black with respect to magenta is detected using magenta as a reference color. In the present embodiment, color shift adjustment of up to two dots is described for ease of explanation, but color shift detection is not limited to two dots.

Hereinafter, a reference pattern and a color misregistration pattern formed on the intermediate transfer member 9 shown in FIG. 1 for detecting a color misregistration amount will be described with reference to FIGS.

FIG. 5 is a schematic diagram showing an example of a reference pattern and a color misregistration pattern formed on the intermediate transfer member 9 shown in FIG. 1 for detecting a color misregistration amount. Is formed, and a color misregistration pattern is formed with cyan.

In the figure, reference numeral 500 denotes a sub-scanning direction on the intermediate transfer member 9 ("+" indicates a sub-scanning direction, and "-" indicates a direction opposite to the sub-scanning direction). 501 is a line pattern block,
A predetermined number of lines each having a width of one dot are formed at intervals of five dots (space) in the sub-scanning direction.

Reference numeral 502 denotes a reference pattern which is similar to the line pattern block 501 (blocks 505 to 5).
11) in the sub-scanning direction. In the present embodiment, the reference pattern 502 is 5 in the sub-scanning direction.
The line pattern is formed at dot intervals, and is a continuous line pattern in the sub-scanning direction of 5 spaces per dot as a whole.

A color shift pattern 503 is the same as the line pattern block 501 (blocks C + 3 to C + 3).
C-3) in the sub-scanning direction. In the present embodiment, the color misregistration pattern 503 is composed of seven blocks (when color misregistration is adjusted up to two dots).
-1, C-2, C-3, C + 1, C + on the minus side in the sub-scanning direction.
2, C + 3. The block interval of each block in the sub-scanning direction is 6 dots, and C0 is formed so as to be located at the same position (in the sub-scanning direction) as the reference pattern block 508 if there is no color shift.

Reference numeral 504 denotes a composite pattern, which is a reference pattern 5
02 and a color shift pattern 503 when the main scanning direction of the color shift pattern 503 matches the main scanning direction. MC0 is a synthesized block obtained by synthesizing the block 508 of the reference pattern and the block C0 of the color shift pattern.
And the block 508 of the reference pattern overlap. MC + 1
Is a composite block of the reference pattern block 507 and the color shift pattern block C + 1. Since the block interval of the color shift pattern is 6 dots and the block interval of the reference pattern is 5 dots, the synthetic block MC + 1 is shifted by 1 dot. It consists of two blocks.

Further, M + 2 is a composite block of the reference pattern block 506 and the color shift pattern block C + 2. The composite block MC + 2 is composed of two blocks shifted by 2 dots, and MC + 3 is the reference pattern block 505 and the color shift pattern. This is a composite block of block C + 3, and the composite block MC + 3 is composed of two blocks shifted by 3 dots.

Similarly, the composite blocks MC-1, MC-
2 and MC-3, the deviation between the reference pattern and the color misregistration pattern is 2 dots, which are shifted by 1 dot, 2 dots, and 3 dots, respectively.
Consists of three blocks. When the color misregistration pattern is formed in this way, if a color misregistration occurs in cyan, the block 50 of the reference pattern
8 and the block C0 of the color shift pattern are shifted.

FIG. 6 is a schematic diagram showing the reference pattern and the color misregistration pattern for detecting the color misregistration amount shown in FIG.
This corresponds to the case where the color shift of one dot occurs.

In the figure, reference numeral 603 denotes a color shift pattern in which the cyan image is shifted by +1 dot in the sub-scanning direction with respect to the magenta image, and the color shift pattern block C0 is shifted by 1 dot in the sub-scanning direction. Block C + 1 of the shift pattern overlaps block 507 of the reference pattern (composite block MC + 1). Also, the combined block MC0 and the combined block MC + 2 on both sides are shifted by one dot, and the combined block MC-1 and the combined block MC + 3 are shifted by 2 dots.

FIG. 7 is a schematic diagram showing a composite pattern of the reference pattern and the color misregistration pattern for detecting the color misregistration amount shown in FIG. 5, wherein the cyan image is +2 dots to the magenta image in the sub-scanning direction. Each case of -2 dot color shift is shown.

Reference numeral 703 denotes a composite pattern when the cyan image has no color shift with respect to the magenta image. When there is no color shift, the reference pattern and the color shift pattern match in the synthetic block MC0. Reference numeral 702 denotes a combined pattern in a case where the cyan image has a color shift of +1 dot with respect to the magenta image.
In the case of a color shift of one dot, the reference pattern matches the color shift pattern in the composite block MC + 1. Reference numeral 701 denotes a combined pattern when the cyan image has a color shift of +2 dots with respect to the magenta image. When the color shift is +2 dots, the reference pattern and the color shift pattern match in the synthesized block MC + 2. Reference numeral 704 denotes a composite pattern when the cyan image has a color shift of -1 dot with respect to the magenta image. When the color shift is -1 dot, the reference pattern and the color shift pattern match in the synthetic block MC-1. Reference numeral 705 denotes a composite pattern when the cyan image has a color shift of −2 dots with respect to the magenta image. In the case of a color shift of −2 dots, the reference pattern matches the color shift pattern in the synthetic block MC-2.

In other words, when the cyan image has a color shift of + N dots with respect to the magenta image, it overlaps with the reference pattern by N blocks in the minus direction in the sub-scanning direction (overlaps with the combined block MC + N). In the case of -N dot color shift,
N blocks are shifted in the + direction in the sub-scanning direction and overlap with the reference pattern (overlap with the combined block MC-N). Therefore, by knowing where the reference pattern and the color misregistration pattern overlap on the intermediate transfer member, it is possible to know the degree of color misregistration (how many dots are misaligned).

Further, as shown in FIG. 4, the density detecting sensor 9c is of a reflection type, and the light emitting portion 400
Light reflected from the light-receiving unit 401 increases, and the sensor output from the density detection sensor 9c increases. In the case of black toner, the light emitting unit 40
The light output from 0 is absorbed, the input light to the light receiving unit 401 decreases, and the sensor output from the light receiving unit 401 of the density sensor 9c decreases.

FIG. 8 is a characteristic diagram showing the distribution (reflection distribution) of the sensor output of the density detection sensor 9c of the reference pattern and the color misregistration pattern of the color toner shown in FIGS. And the vertical axis indicates the density detection sensor 9c.
5 shows the sensor output of the first embodiment.

In the figure, reference numeral 801 denotes a reflection distribution of a line pattern when a reference pattern and a color misregistration pattern of a color toner (for example, cyan) overlap (one dot and five spaces).

In the reflection distribution 801, reference numeral 807 denotes a sensor output of the density detecting sensor 9c for a line pattern of one dot and five spaces, and 804 denotes a density detecting sensor 9c in a state where a developed image is not formed on the surface of the intermediate transfer member 9.
, Ie, the sensor output on the surface of the intermediate transfer member 9 is shown.

Reference numeral 802 denotes a case where the color shift pattern between the reference pattern and the color toner is shifted by one dot (two dots and four spaces).
3 shows the reflection distribution of the line pattern.

In the reflection distribution 802, reference numeral 808 denotes a sensor output of the density detection sensor 9c for a color shift pattern (cyan line pattern), and reference numeral 809 denotes a sensor output of the density detection sensor 9c for a reference pattern (magenta line pattern). , 812 indicate the sensor output of the density detection sensor 9c for the line pattern of two dots and four spaces. Reference numeral 805 denotes a sensor output on the surface of the intermediate transfer member 9.

Reference numeral 803 denotes a case where the reference pattern and the color shift pattern of the color toner are shifted by 3 dots (one dot and two spaces).
3 shows the reflection distribution of the line pattern.

In the reflection distribution 803, reference numeral 810 denotes a sensor output of the density detection sensor 9c for a reference pattern (magenta line pattern), and reference numeral 811 denotes a sensor output of the density detection sensor 9c for a color shift pattern (cyan line pattern). , 813 indicate the sensor output of the density detection sensor 9c with respect to the line pattern of one dot and two spaces). Reference numeral 806 denotes a sensor output on the surface of the intermediate transfer body 9.

The sensor output of the color misregistration pattern of the color toner exhibits an upwardly convex reflection distribution which is maximum at the line portion, and the output amount of the density detection sensor 9c is obtained by integrating these. Therefore, in the case of the reflection distribution 802 of the line pattern of two dots and four spaces, the sensor output amount is increased by one dot as compared with the case of the reflection distribution 801 of the line pattern of one dots and five spaces.

In the case of the reflection distribution 803 of the line pattern of one dot and two spaces, the sensor outputs projecting upward at two dot intervals overlap each other. Competence increases. That is, the output of the density sensor differs depending on the interval between the one-dot lines generated by combining two blocks (the block of the color misregistration pattern and the block of the reference pattern). The output of the detection sensor becomes maximum.

As described above, the displacement between the block of the color misregistration pattern and the block of the reference pattern by the color toner can be detected from the sensor output amount of the density sensor 9c.

FIG. 9 is a characteristic diagram showing the sensor output of the density detection sensor 9c of the reference pattern shown in FIGS. 5 to 7 and the color misregistration pattern of the color toner. This corresponds to the case where there is no color difference (that is, the case where the reference pattern and the color toner are MC0 and there is no color shift). In addition,
The horizontal axis shows the position in the sub-scanning direction, and the vertical axis shows the sensor output of the density detection sensor 9c.

In the figure, reference numeral 907 denotes a density detection sensor 9 in a state where a developed image is not formed on the surface of the intermediate transfer member 9.
c shows the sensor output, that is, the sensor output on the surface of the intermediate transfer member 9. Reference numeral 900 denotes a sensor output of the density detection sensor 9c in the composite block MC0, and reference numeral 901 denotes a composite block MC.
-1 at the sensor output of the density detection sensor 9c, 90
2 is a density detection sensor 9c in the synthesis block MC-2.
903 is the sensor output of the density detection sensor 9c in the synthesis block MC-3.

Reference numeral 904 denotes a sensor output of the density detection sensor 9c in the composite block MC + 1, reference numeral 905 denotes a sensor output of the density detection sensor 9c in the composite block MC + 2, and reference numeral 903 denotes a sensor output of the density detection sensor 9c in the composite block MC + 3. is there.

As shown in the reflection distribution 801 in FIG. 8, the output of the density detection sensor 9c is minimized in the composite block MC0 having no shift, and as shown in the reflection distributions 802 and 803 in FIG. Each time the displacement increases (composite blocks MC-1, MC-2, MC-3, composite block MC
The sensor output increases to (+1, MC + 2, MC + 3).

Each synthesized block (synthesized block MC-1,
MC-2, MC-3, composite block MC + 1, MC +
2, MC + 3), the magnitude relation of the sensor output is “9
00 <901 <902 <903, 900 <904 <90
5 <906 ”.

FIG. 10 is a characteristic diagram showing the distribution (reflection distribution) of the sensor output of the density detection sensor 9c of the reference pattern and the color misregistration pattern of the black toner. The horizontal axis shows the position in the sub-scanning direction, and the vertical axis shows the position. Shows the sensor output of the density detection sensor 9c.

In the figure, reference numeral 1001 denotes the reflection distribution of a line pattern when the reference pattern and the color shift pattern of black toner (black) overlap (one dot and five spaces).

In the reflection distribution 1001, 1007 is 1
A sensor output of the density detection sensor 9c for a (black) line pattern of five dots is shown, and 1004 indicates a sensor output of the surface of the intermediate transfer body 9.

Reference numeral 1002 denotes the reflection distribution of the line pattern when the color shift pattern of the reference pattern and the color toner is shifted by one dot (two dots and four spaces).

In the reflection distribution 1002, reference numeral 1008 denotes a sensor output of the density detection sensor 9c with respect to a reference pattern (magenta line pattern); reference numeral 1009 denotes a sensor output of the density detection sensor 9c with respect to a color misregistration pattern of black toner; The sensor output of the density detection sensor 9c for a (magenta, black) line pattern of two dots and four spaces is shown. Reference numeral 1005 denotes a sensor output on the surface of the intermediate transfer body 9.

Reference numeral 1003 denotes a reflection distribution of the line pattern when the reference pattern and the color shift pattern of the black toner are shifted by 3 dots (one dot and two spaces).

In the reflection distribution 1003, reference numeral 1011 denotes a sensor output of the density detection sensor 9c for the reference pattern (magenta), reference numeral 1012 denotes a sensor output of the density detection sensor 9c for the color shift pattern (black),
Reference numeral 1013 denotes a sensor output of the density detection sensor 9c for a line pattern of one dot and two spaces). 1006
Indicates a sensor output on the surface of the intermediate transfer member 9.

Since the black toner absorbs the light output from the sensor, as shown in the reflection distribution 1001, the sensor output 1007 of one dot and five spaces is smaller than the sensor output 1004 of the reflected light on the surface of the intermediate transfer member. You. Also, 2
The sensor output 1010 of the dot 4 space is the light reflected by the color toner (the sensor output 100 of the reference pattern).
8) and light absorbed by the black toner (sensor output 1009 of the color misregistration pattern of the black toner), and the sensor output amount of the density detection sensor 9c is equal to the reflection distribution 1
001 (sensor output 10 of 5 dots per space)
More than 7).

Similarly, when the color misregistration of black advances and the color misregistration pattern of the black toner deviates by three dots, one dot
The sensor output 1011 of the space is obtained by synthesizing the light reflected by the color toner (sensor output 1011 of the reference pattern) and the light absorbed by the black toner (sensor output 1012 of the color misregistration pattern of the black toner). The sensor output amount of the sensor 9c is larger than that in the case of the reflection distribution 1002 (sensor output 1010 of two dots and four spaces).

Therefore, it is possible to know both the color misregistration of the color toner and the color misregistration of the black toner by monitoring the place where the output of the density detecting sensor 9c is minimum, and to know the place where the minimum is detected. It is possible to know the degree of color misregistration.

FIG. 11 is a schematic diagram showing an example of the formation positions of the reference pattern and the color misregistration pattern formed on the intermediate transfer member 9 shown in FIG.

In the drawing, reference numeral 1101 denotes a reference pattern.
The toner (developer 1) other than the black toner has a length of “1108 + 1109 + 1110” in the sub-scanning direction on the intermediate transfer member 9. Reference numeral 1102 denotes a first color misregistration pattern, which is a toner (developer 2) other than the developer 1 and an intermediate transfer member 9;
It is formed with a length of 1108 in the upper sub-scanning direction. Reference numeral 1103 denotes a central block of the first color shift pattern 1102, which corresponds to C0 shown in FIGS. 110
Reference numeral 4 denotes a second color misregistration pattern, which is a toner (developer 3) other than the developers 1 and 2 in the sub-scanning direction on the intermediate transfer body 9 in the sub-scanning direction.
It is formed with a length of nine. Reference numeral 1105 denotes a center block of the second color shift pattern 1104, which corresponds to C0 shown in FIGS. Reference numeral 1106 denotes a third color shift pattern, which is formed of a toner (developer 4) other than the developers 1 to 3 and has a length of 1110 on the intermediate transfer member 9 in the sub-scanning direction. Reference numeral 1107 denotes a central block of the third color shift pattern 1106, which corresponds to C0 shown in FIGS.

The color misregistration patterns are formed so as not to overlap each other.

The image forming apparatus of the present invention forms all developer images based on a timer based on a TOP signal. The reference pattern 1101 starts image formation at the same timing as the image formation start timing of the first color shift pattern 1102, and ends image formation at the same timing as the image formation end timing of the third color shift pattern 1106.

When these developer images are formed so as to overlap each other in the main scanning direction, if there is no color shift, blocks 1103, 1105, 11 at the center of each color shift pattern.
07 and the reference pattern 1101 are formed so as to overlap each other.

Hereinafter, an example of the color misregistration amount detection operation of the image forming apparatus of the present invention will be described with reference to the flowchart of FIG.

FIG. 12 is a flowchart illustrating an example of a procedure for detecting the amount of color misregistration of the image forming apparatus according to the present invention, and is executed by the main control CPU 201 based on the program stored in the ROM 201a shown in FIG. Note that (1) to (14) indicate each step.

First, a reference pattern and a color shift pattern are formed. However, the reference pattern and the color misregistration pattern are formed on the condition that the reference pattern is not the black toner and that the reference pattern is formed before the color misregistration pattern of the black toner is formed.

As shown in FIG. 11, a reference pattern is formed with developer 1 which is not black toner (1), and a color misregistration pattern is formed with developer 2, developer 3 and developer 4, respectively (2). ~ (4). Here, it is assumed that the image information of the reference pattern and the color misregistration pattern formed in the steps (1) to (4) is stored in the ROM 201a or a recording medium (not shown).

After forming the reference pattern and the color shift pattern, the density detection sensor 9c measures the reference pattern and the color shift pattern formed on the intermediate transfer member 9.

The density detection sensor 9c has a T
The timer based on the OP signal is constantly monitored.
Block 110 at the center of each color shift pattern indicated by 1
3, 1105, 1107 and each position where the reference pattern 1101 overlaps (each position at which the sensor output of the density detection sensor is minimized) is detected, and each time from the TOP signal (time for each developer) is stored in the RAM 201b. Remember (5).

The TO of the developer 2 stored in step (5)
The time from the P signal is compared with the time from the TOP signal forming the original central block 1103 of each color shift pattern, and the degree (dot) of color shift of the developer 2 is determined (6). If it is determined that there is a color shift in the developer 2, the color shift amount of the developer 2 is stored in the RAM 201 b shown in FIG.
(7), and proceeds to step (9) to process the next developer.

On the other hand, if it is determined in step (6) that the developer 2 has no color misregistration, the RAM 20 shown in FIG.
The color misregistration amount of the developer 2 stored in 1b is cleared (8), and the process proceeds to step (9) to process the next developer.

Next, the developer 3 stored in step (5)
The time from the TOP signal is compared with the time from the TOP signal forming the block 1105 at the center of each original color misregistration pattern to determine the degree (dot) of color misregistration of the developer 3 (9). If it is determined that the developer 3 has a color shift, the color shift amount of the developer 3 is stored in the RAM 201 shown in FIG.
b (10), and proceeds to step (12) to process the next developer.

On the other hand, if it is determined in step (9) that there is no color shift in the developer 3, the RAM 20 shown in FIG.
The color shift amount of the developer 3 stored in 1b is cleared (11), and the process proceeds to step (12) to process the next developer.

Next, the developer 4 stored in step (5)
The time from the TOP signal is compared with the time from the TOP signal forming the block 1105 at the center of the original color misregistration pattern to determine the degree (dot) of color misregistration of the developer 4 (12). If it is determined that the developer 4 has a color shift, the color shift amount of the developer 4 is stored in the RAM 20 shown in FIG.
1b (13), and the process ends.

On the other hand, if it is determined in step (12) that the developer 4 has no color shift, the RAM 2 shown in FIG.
The amount of color misregistration of the developer 4 stored in 01b is cleared (14), and the process ends.

With the above processing, the color shift amounts of the developer 2 to the developer 4 with respect to the developer 1 are respectively stored in the RAM 2.
01b.

The color misregistration amount detection operation shown in FIG. 12 may be started by an instruction from an operation panel or the like (not shown).

Thus, a simple operation of instructing the execution of the color misregistration detection operation from the operation panel or the like can be performed.
Anytime, anyone can automatically adjust the color shift due to mechanical accuracy and the like.

Further, the operation for detecting the amount of color misregistration shown in FIG.
You may be comprised so that it may start under certain starting conditions, such as at the time of replacement | exchange of Y, 20M, 20C, and 21B.

Thus, when the power is turned on, the photosensitive drum 15
When the developer is replaced, the color shift amount stored in the RAM 201b is updated each time the developing units 20Y, 20M, 20C, and 21B are replaced, so that aging and a shift in mechanical accuracy such as component replacement can be corrected. it can.

Hereinafter, an example of the color misregistration correction operation of the image forming apparatus of the present invention will be described with reference to the flowchart of FIG.

FIG. 13 is a flowchart for explaining an example of a procedure for correcting a color misregistration of the image forming apparatus of the present invention.
1 executes. Note that (1) to (13) indicate each step.

First, a developer image of a reference color (color toner used as a basic pattern) is formed (1). However, it is not necessary to first form the reference color developer image. Next, the color shift amount of the developer 2 is obtained from the RAM 201b (2),
It is determined whether or not there is a color shift (3). If it is determined that there is a color shift, the image forming start position of the developer 2 (the image forming start time from the generation of the TOP signal) is determined according to the color shift amount. ) Is changed (4), and an image of the developer 2 is formed (5).

On the other hand, if it is determined in step (3) that there is no color misregistration, an image of the developer 2 is formed without changing the image formation start position of the developer 2 (5).

Next, the amount of color shift of the developer 3 is stored in the RAM 201b.
(6), it is determined whether or not there is a color shift (7). If it is determined that there is a color shift, the image forming start position (TOP signal) of the developer 3 is determined according to the amount of color shift. (Image formation start time from occurrence) is changed (8), and developer 3
(9).

On the other hand, if it is determined in step (7) that there is no color misregistration, the image of the developer 3 is formed without changing the image formation start position of the developer 3 (9).

Next, the amount of color misregistration of the developer 4 is stored in the RAM 201b.
(10), it is determined whether or not there is a color shift (11). If it is determined that there is a color shift, the image forming start position (TOP signal) of the developer 4 is determined according to the amount of color shift. The image forming start time from the occurrence is changed (12), an image of the developer 4 is formed (13), and the process is terminated.

On the other hand, if it is determined in step (11) that there is no color misregistration, the image of the developer 4 is formed without changing the image formation start position of the developer 4 (13), and the processing is performed. finish.

As described above, when there is a color shift between the developer 2, the developer 3, and the developer 4, the image forming start position of each developer (the image forming start time from the generation of the TOP signal) is determined according to the amount of the color shift. ) Is changed to form each image, and if there is no color shift, an automatic correction is performed by forming each developer image without changing the image formation start position to form an image without color shift. be able to.

In the present embodiment, the color shift amounts of the developer 2 to the developer 4 with respect to the
Although the case where the data is individually stored in the M201b has been described, three different memories may be newly provided, and the color misregistration amounts of the developer 2 to the developer 4 may be stored in the different memories.

Further, in the present embodiment, the color shift amounts of the developer 2 to the developer 4 with respect to the developer 1 are each set to R.
AM 201b is stored in NVRA.
A non-volatile memory such as an M, an EEPROM, a non-volatile memory card, or the like may be provided, and the amount of color misregistration of the developer 2 to the developer 4 may be stored in the non-volatile memory.

Thus, the predetermined period, the drum unit 13, the developing units 20Y, 20M, 20C, 21
B. The color misregistration amount is detected only when parts such as units of each developer are replaced, and when necessary, and it is not necessary to detect the color misregistration amount of each developer every time the power is turned on. A color image without color shift can be formed in a short first print time.

The case of detecting a two-dot color shift using the composite pattern of the reference pattern for color shift correction and the color shift pattern shown in FIGS. 5 to 7 has been described above. The case of detecting a color shift of N dots will be described with reference to FIG.

FIG. 14 is a schematic diagram showing a composite pattern of a reference pattern and a color misregistration pattern formed on the intermediate transfer member 9 shown in FIG. 1 for color misregistration correction. No color shift in the sub-scanning direction ~ +3
This corresponds to the case where the dot color has shifted.

As in the case of FIGS. 5 to 9, the reference pattern has a structure in which a line pattern of one dot and five spaces is combined with one block at intervals of five dots in the sub-scanning direction. This is a line pattern that is continuous in the scanning direction. Similarly to the reference pattern, the color misregistration pattern has a configuration in which blocks each including a line pattern of five dots per space as one block are combined in the sub-scanning direction at intervals of six dots.

Reference numeral 1401 denotes a composite pattern in the case where there is no color shift. If there is no color shift, the reference pattern and the color shift pattern coincide in the synthesized block MC0. Reference numeral 1402 denotes a composite pattern when the cyan image has a color shift of +1 dot.
In the case of a color shift of +1 dot, the reference pattern matches the color shift pattern in the composite block MC + 1. Reference numeral 1403 denotes a composite pattern when the cyan image has a color shift of +2 dots.
In 2, the reference pattern and the color misregistration pattern match.

Reference numeral 1404 denotes a composite pattern when the cyan image has a color shift of +3 dots. In the case of a color shift of +3 dots, the reference pattern and the color shift pattern are not only in the synthetic block MC + 3 but also in the synthetic block MC-3. They match, and it cannot be determined whether the color shift is +3 dots or -3 dots. Thus, in the blocks at both ends,
No color shift can be determined.

Generally, in order to detect a color shift of “± N” dots (N is a natural number), the color shift pattern requires “N × 2 + 3” blocks in the sub-scanning direction. Further, the space between the lines of the block also depends on the detection width of the color shift, and in order to detect the color shift of “± N” dots, the space between the lines of the block is “N × 2 + 1” in the sub-scanning direction. Dot space is required. Accordingly, the block interval of the reference pattern is “N × 2 + 1” dots, and the block interval of the color misregistration pattern is “N × 2 + 2” dots that are “1” dots wider than the block interval of the reference pattern.

By forming the reference pattern and the color shift pattern as described above on the intermediate transfer member 9 and executing the processing shown in the flowchart of FIG. 12, the color shift amount of N dots can be detected. Thus, the color shift automatic adjustment can be performed by the processing shown in the flowchart of FIG.

[Second Embodiment] In the first embodiment,
Although the case where images of different colors are sequentially formed on one photosensitive drum 13 and sequentially transferred to the intermediate transfer body 9 has been described,
A photosensitive drum may be provided for each of the Y, M, C, and B colors, and an image formed on the photosensitive drum for each color may be transferred onto an intermediate transfer member.
Hereinafter, the embodiment will be described.

FIG. 15 is a sectional view showing a configuration of a laser beam printer to which the image forming apparatus according to the second embodiment of the present invention can be applied. The same components as those in FIG. is there.

In the figure, 44Y, 44M, 44C, 4
Reference numeral 4B denotes a laser scanner unit for each color, and based on each color image signal inputted, each photosensitive drum 40Y, 40M,
Exposure scanning is performed on the photosensitive drums 40C and 40B, and the photosensitive drums 40 of the respective colors are scanned.
An electrostatic latent image is formed on Y, 40M, 40C, and 40B.
41Y, 41M, 41C and 41B are color developing cartridges for developing the electrostatic latent images formed on the photosensitive drums 40Y, 40M, 40C and 40B with the respective color developing agents. Reference numeral 42 denotes an intermediate transfer belt, and each photosensitive drum 40Y, 40M, 40
C, 40B, and temporarily holds the developer of each color.
The image is transferred to a transfer material conveyed to the transfer roller 3.

In the above configuration, the reference pattern 1101, the first color shift pattern 1102, the second color shift pattern 1104, and the third color shift pattern 1 shown in FIG.
106 is formed on the intermediate transfer belt 42, and the density detection sensor 9c disposed near the intermediate transfer belt 42
The present invention can be applied by detecting and automatically correcting color misregistration of a plurality of toner color images.

Further, the color is transferred onto the intermediate transfer member 9 under certain start-up conditions such as operation from an operation panel (not shown), power-on, replacement of the photosensitive drum 15, replacement of the developing units 20Y, 20M, 20C, and 21B. A developer image for misregistration is formed, and the reflection density of the developer image is measured by a density detection sensor 9c disposed near the intermediate transfer member 9 to determine the degree of color misregistration. The printing may be configured to automatically correct the misalignment.

As described above, in an image forming apparatus for sequentially forming a plurality of toner color images on an intermediate transfer member and transferring the formed toner color image to a print medium, an optical sensor disposed near the intermediate transfer member is used for the image forming apparatus. By detecting and automatically correcting the color misregistration of a plurality of toner color images, it is possible to automate color misregistration adjustment work due to mechanical accuracy and the like at a factory, as well as vibration and component replacement after shipment. In addition, it is possible to automatically correct color misregistration caused by mechanical accuracy due to aging and the like.

Further, the optical sensor is used in combination with an optical density detection sensor arranged near the intermediate transfer member to control the density of the toner color image, so that high quality and small image quality without color shift can be obtained. An image forming apparatus in a space can be provided at low cost.

Further, a developer image for adjusting color misregistration is formed on the photosensitive drum under certain start-up conditions such as operation from the operation panel or when the power is turned on, when the photosensitive drum is used, and when the developing device is replaced, and is disposed near the drum. The density detection sensor measures the reflection density of the developer image, determines the amount of color misregistration, and automatically corrects the color misregistration when performing normal printing thereafter to perform printing, thereby always providing a stable color image. Becomes possible. Further, it is not necessary to adjust the color misregistration at the factory, and the burden on the factory can be reduced.

The present invention is also applicable to a case where a multi-color image is formed based on multi-color print information input from an information processing apparatus via a predetermined communication medium. May be configured to form a multi-color image based on a multi-color image read by scanning.

As described above, the storage medium storing the program codes of the software for realizing the functions of the above-described embodiments is supplied to the system or the apparatus, and the computer (or CPU or MP) of the system or the apparatus is supplied.
It goes without saying that the object of the present invention is also achieved when U) reads out and executes the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, C
DR, magnetic tape, nonvolatile memory card, RO
M, EEPROM and the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) And the like perform part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instruction of the program code, The CPU provided in the function expansion board or function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, the present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus. In this case, by reading a storage medium storing a program represented by software for achieving the present invention into the system or the apparatus, the system or the apparatus can enjoy the effects of the present invention. .

Further, by downloading and reading out a program represented by software for achieving the present invention from a database on a network by a communication program, the system or apparatus can be
It is possible to enjoy the effects of the present invention.

[0141]

As described above, the first, fifth to eighth eighth
According to the invention, in an image forming apparatus for forming a multi-color image by sequentially superposing a plurality of color images formed in different colors on an image carrier, a first pattern is formed on the image carrier by a predetermined color. And forming a second pattern different from the first pattern on the image carrier by another color different from the predetermined color so as to overlap the first pattern to be formed. The first control means controls the image formation, and determines the amount of deviation between the image of the predetermined color and the image of the other color from a composite pattern of the first and second patterns formed on the image carrier. The second control means controls the image forming position of the image of the other color based on the amount of deviation detected by the detection means and detected by the detection means. Automatically adjusts the deviation to provide high quality It is possible to form a color image.

According to the second aspect, the detecting means detects the image density by optically measuring the reflected light of the image formed on the image carrier, and detects the image density. The means controls the image forming density based on the image density detected by the detecting means. Therefore, an existing optical density detecting sensor disposed near the intermediate transfer member to control the density of the toner color image. By using a sensor for detecting color misregistration in combination with the above, it is possible to provide an inexpensive, high-quality image forming apparatus without color misregistration in a small space.

According to the third and fourth aspects of the present invention, the storage means (non-volatile storage means) for storing a shift amount between the image of the predetermined color and the image of the other color detected by the detection means. Is provided, the detected color misregistration amount is stored, and the color misregistration detection operation can be omitted to form a high-quality image in a short time.

According to a ninth aspect of the present invention, the first control means is instructed to form first and second patterns, and the first and second patterns are instructed to the detecting means. An instruction means for instructing detection of a shift amount between the image of the predetermined color and the image of the other color from the combined pattern of the patterns is provided. Anyone can automatically adjust the color misregistration due to mechanical accuracy or the like at any time with simple operation.

According to the tenth aspect, in the color misregistration correction method of the image forming apparatus for forming a multi-color image by superimposing each color image formed in different colors on the image carrier, the first color is determined by the predetermined color. A pattern is formed on the image carrier, and a second image pattern different from the first pattern by another color different from the predetermined color is superimposed on the first pattern to be formed. Forming a shift amount between an image of the predetermined color and an image of the other color from a composite pattern of the first and second patterns formed on the body and superimposed on the image carrier; Since the other color image is formed at a position based on the shift amount, the color shift due to mechanical accuracy or the like can be automatically adjusted with a simple configuration, and a high-quality multicolor image can be formed.

Therefore, with a simple configuration, it is possible to form a high-quality multicolor image by automatically adjusting the color misregistration due to mechanical accuracy or the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a laser beam printer to which an image forming apparatus according to a first exemplary embodiment of the present invention can be applied.

FIG. 2 is a block diagram illustrating a schematic configuration of an engine unit of the image forming apparatus according to the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of the intermediate transfer member shown in FIG.

FIG. 4 is a block diagram illustrating a configuration of an image density detection control unit of the image forming apparatus according to the present invention.

5 is a schematic diagram illustrating an example of a reference pattern and a color shift pattern for detecting a color shift amount formed on the intermediate transfer member illustrated in FIG. 1;

6 is a schematic diagram showing a reference pattern and a color shift pattern for detecting a color shift amount shown in FIG. 5;

FIG. 7 is a schematic diagram showing a composite pattern of a reference pattern and a color shift pattern for detecting the amount of color shift shown in FIG. 5;

8 is a characteristic diagram showing a distribution (reflection distribution) of a sensor output of a density detection sensor of a reference pattern and a color misregistration pattern of color toner shown in FIGS.

FIG. 9 is a characteristic diagram illustrating sensor outputs of a density detection sensor of the reference pattern and the color misregistration pattern of the color toner illustrated in FIGS. 5 to 7;

FIG. 10 is a characteristic diagram showing a distribution (reflection distribution) of a sensor output of a density detection sensor of a reference pattern and a color shift pattern of black toner.

FIG. 11 is a schematic diagram illustrating an example of a position where a reference pattern and a color misregistration pattern are formed on the transfer body illustrated in FIG. 1;

FIG. 12 is a flowchart illustrating an example of a color misregistration amount detection procedure of the image forming apparatus of the present invention.

FIG. 13 is a flowchart illustrating an example of a color misregistration correction procedure of the image forming apparatus of the present invention.

FIG. 14 is a schematic diagram showing a composite pattern of a reference pattern and a color misregistration pattern formed on the intermediate transfer member shown in FIG. 1 for color misregistration correction.

FIG. 15 is a cross-sectional view illustrating a configuration of a laser beam printer to which the image forming apparatus according to the second embodiment of the present invention can be applied.

[Explanation of symbols]

 Reference Signs List 9 intermediate transfer member 9c density detection sensor 10 transfer roller 15 photosensitive drum 20Y yellow developing device 20M magenta developing device 20C cyan developing device 21B black developing device 201 main control CPU 201a ROM 201b RAM

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C262 AA05 AA17 AA24 AA26 AB15 AC07 FA06 GA04 GA34 GA39 GA42 GA57 2H027 DA09 DA38 DE02 EB04 EC03 EC06 EC20 ED06 ED24 EE02 EE07 EF09 2H030 AA01 AD12 BB02 BB16 BB23 BB23 MM27 MP08 PP15 PP23 PP33 PP39 PP43 PP47 PQ22 SS02 TT02 5C079 HA09 HA19 HB03 KA03 KA17 KA18 LA01 LA11 MA01 MA10 NA02 PA03

Claims (10)

[Claims] An image forming apparatus for forming a multi-color image by sequentially superimposing a plurality of color images formed in different colors on an image carrier, wherein a first pattern of a predetermined color is formed on the image carrier. And controlling to form a second pattern different from the first pattern on the image carrier by another color different from the predetermined color so as to overlap the first pattern to be formed. First control means, and detection for detecting a shift amount between an image of the predetermined color and an image of the other color from a composite pattern of the first and second patterns formed on the image carrier. An image forming apparatus, comprising: means for controlling an image forming position of an image in another color based on a shift amount detected by the detecting means. 2. The image processing apparatus according to claim 1, wherein the detecting unit detects an image density by optically measuring a reflected light of the image formed on the image carrier. 2. The image forming apparatus according to claim 1, wherein the image forming density is controlled based on the image density detected by the image forming apparatus. 3. The image forming apparatus according to claim 1, further comprising a storage unit configured to store a shift amount between the image of the predetermined color and the image of the other color detected by the detection unit. . 4. The image forming apparatus according to claim 3, wherein said storage unit is a nonvolatile storage unit. 5. The first pattern is a block in which a predetermined number of lines each having a predetermined width extending in the main scanning direction are arranged in the sub-scanning direction at a first interval. The said 2nd pattern WHEREIN: The said 2nd pattern is what arranged the predetermined number of the said block by the 2nd space | interval different from the said 1st space | interval in a sub-scanning direction. Image forming apparatus. 6. The image forming apparatus according to claim 5, wherein the second interval is wider by one pixel in the sub-scanning direction than the first interval. 7. The image forming apparatus according to claim 1, wherein an image is formed based on print information input from the information processing apparatus via a predetermined communication medium. 8. The image forming apparatus according to claim 1, wherein an image is formed based on a multicolor original image read from the original. 9. The control device according to claim 1, wherein:
And forming a second pattern, and instructing the detection means to detect a shift amount between the image of the predetermined color and the image of the other color from the composite pattern of the first and second patterns. 2. The image forming apparatus according to claim 1, further comprising an instruction unit for instructing the image forming apparatus. 10. A color misregistration correction method for an image forming apparatus for forming a multicolor image by superimposing each color image formed in different colors on an image carrier, wherein the first pattern is formed by a predetermined color on the image carrier. A first pattern forming step to be formed thereon, and a second pattern different from the first pattern by another color different from the predetermined color so as to overlap the first pattern to be formed.
A second pattern forming step of forming a pattern on the image carrier; and forming an image of the predetermined color from the composite pattern of the first and second patterns formed on the image carrier. A color difference correction method for an image forming apparatus, comprising: a detection step of detecting a shift amount from an image due to the color of the image; and an image forming step of forming the other color image at a position based on the shift amount. .