JP2001109205A - Image forming device, image forming method and recording medium with image formation control program recorded thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively correct the fluctuation of output image density by using a simply constituted image density detecting means whose reliability is high, and which does not make the size of a device unnecessarily larger in an electrophotographic system image forming device. SOLUTION: Image density is controlled by density detection control on a photoreceptor drum being a first density control mode. Besides, when density detection control on a transfer belt being a second density control mode is performed, reference standard density being the target value of the density control on the transfer belt is decided for each consecutive image forming process in a state where desired image density is nearly obtained by the density detection control on the photoreceptor drum being the first density control mode, so that image density during the progress of each consecutive image forming process can be extremely and stably controlled. The condition of image formation can be kept well without being influenced by the secular change of the staining and the damage, etc., of the transfer belt, the fluctuation of an image density detecting sensor characteristics by deciding the reference standard density for each consecutive image formation.

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 such as a copying machine of an electrophotographic type or an electrostatic recording type, a printer, etc. Image forming apparatus, image forming method, and image forming control for forming an electrostatic latent image corresponding to an image pattern of a plurality of colors, developing the electrostatic latent image, and sequentially transferring the electrostatic latent image onto a recording material or an intermediate transfer body The present invention relates to a recording medium on which a program is recorded.

[0002]

2. Description of the Related Art Conventionally, there has been a technique for forming a reference image on a photoreceptor, detecting the density of the reference image, and controlling the density in accordance with the detection result, thereby improving the stability of image quality. Are known.

[0003]

However, as described above, the density of the reference image formed on the photoreceptor is detected,
When performing image density control according to this detection result, if the image density detecting means is disposed immediately after the developing means and immediately before the transfer means, the image density detecting means performs stable development and the apparatus size is reduced. Was an obstacle in reducing the size.

Further, there has been a problem that the image density detecting means is stained by the adhesion of the free developer from the developing means. In order to avoid these problems, if the image density detecting means is arranged at the subsequent stage of the transfer means, it is difficult to separate or stop the transfer means during continuous image formation. Cannot be performed, and the image density fluctuates.

Alternatively, when the density of the reference image formed on the transfer member is detected and the image density is controlled in accordance with the detection result, it is difficult to accurately detect the image density due to scratches and dirt on the transfer member. In addition, when image density detection is performed on a generally used sheet-type transfer body, the mounting position accuracy required for the image density detection means is extremely high, so that designing is difficult. There is a problem that there are environmental fluctuations and endurance fluctuations in efficiency, and it is difficult to accurately detect image density.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to use a highly reliable and simple image density detecting means without unnecessarily increasing the size of the apparatus. It is another object of the present invention to provide an image forming apparatus and an image forming method capable of effectively correcting a change in output image density, and a recording medium on which an image forming control program is recorded.

[0007]

In order to achieve the above object, according to the present invention, a first reference image is formed on a photosensitive member, and the first reference image formed on the photosensitive member is provided. Detection means for detecting the density of the image, first control means for controlling the image forming apparatus based on the detection result detected by the first detection means, and a second reference image on the photosensitive member. Forming a second reference image formed on the photoreceptor, transferring the second reference image on a transfer member, and detecting a density of the second reference image transferred on the transfer member. Second control means for controlling the image forming apparatus based on the detection result detected by the second detection means, and the second control means based on the control result by the first control means. It is characterized in that the control of is adjusted.

In order to achieve the above object, a second aspect of the present invention is to form a first reference image on a photoreceptor and detect the density of the first reference image formed on the photoreceptor. A first detection unit, a first control unit for controlling an image forming apparatus based on a detection result detected by the first detection unit, a second reference image formed on the photoconductor, After transferring the second reference image formed thereon onto a transfer body, a second detection means for detecting the density of the second reference image transferred onto the transfer body; And a second control unit for controlling a correction value of the gradation correction unit of the image forming apparatus based on a detection result detected by the detection unit, wherein the second control unit controls the second control unit based on a control result of the first control unit. The control of the control means is adjusted.

Here, a target value of the control of the second control means may be adjusted based on a control result of the first control means.

[0010] According to another aspect of the present invention, a control target value of the second control unit is adjusted in accordance with an operation state of the image forming apparatus based on a control result of the first control unit.

Further, the control of the second control means may be performed during an interval of control by the first control means.

The first detecting means for detecting the first reference image irradiates a detection light on the reference image on the photoreceptor and detects a reflected light or a transmitted light thereof. It is characterized in that the density of the reference image or the amount of adhering image forming agent is detected.

Further, the second detecting means for detecting the second reference image irradiates the reference image on the transfer member with detection light and detects reflected light or transmitted light thereof. The method may be characterized in that the density of the reference image or the amount of the image forming agent attached is detected.

Further, the transfer member is an image carrier such as an intermediate transfer member, and the second reference image transferred onto the image carrier is detected by the second detecting means. can do.

The transfer member is a recording material carrier such as a recording material conveying belt, and the second reference image directly transferred onto the recording material carrier is detected by the second detecting means. It can be characterized.

Further, the first reference image may be a single color or a fixed density pattern including each color component of a color image.

Further, the second reference image may be a single color or a constant density pattern including each color component of a color image.

Further, the control by the first control means is as follows:
The image density control for adjusting the density of the developer can be characterized.

The control by the second control means is as follows:
The image density control for adjusting the density of the developer can be characterized.

Further, the control by the second control means is as follows:
The control may be a control for adjusting the exposure amount or the latent image contrast.

The control by the second control means is as follows:
An image density and gradation control for correcting and controlling a gradation correction LUT (look-up table) for correcting input image data can be provided.

Further, the control by the second control means is as follows:
By adjusting the developer supply amount and controlling the developer density so that the parameter calculated from the detected detection signal of the second reference image becomes the target value, the image density or the gradation characteristic is improved. And controlling the target value based on a control result by the first control means.

Further, the image forming apparatus forms an electrostatic latent image corresponding to an image pattern on the photoreceptor, develops the electrostatic latent image, and transfers the developed image onto a recording material. Can be characterized.

Further, the image forming apparatus forms an electrostatic latent image corresponding to the image pattern on the photosensitive member, develops the electrostatic latent image, and transfers the developed image to an intermediate transfer member. ,
The image can be transferred onto a recording material.

Further, the image forming apparatus is characterized in that a color image is formed by sequentially forming images of a plurality of colors.

Further, the image forming apparatus has a plurality of photosensitive members, and forms a color image by transferring a plurality of visible images formed on the plurality of photosensitive members onto a recording material. It can be a feature.

In order to achieve the above object, an invention according to claim 21 forms an electrostatic latent image corresponding to a plurality of color image patterns on a single photoconductor sequentially or on a plurality of photoconductors. After developing the electrostatic latent image, in a color image forming apparatus that sequentially transfers the image onto a recording material or an intermediate transfer member, a first reference density pattern of each color is formed on the photoconductor, First detection means for detecting the density of the first reference density pattern by irradiating the detection light on the first reference density pattern and detecting the reflected light thereof, and detecting the density of the first reference density pattern by the first detection means. First control means for controlling an image density of an output image by controlling a toner density by adjusting a toner supply amount so that a density of the first reference density pattern becomes a target value; The second reference density pattern of each color is After forming the second reference density pattern on the recording material transporting body or the intermediate transfer body, the second reference density pattern is irradiated with detection light to detect reflected light or transmitted light. Thereby, the second detecting means for detecting and detecting the density of the second reference density pattern, and the density of the second reference wetness pattern detected by the second detecting means are set to the target value. Second control means for controlling the image density of the output image by controlling the toner density by adjusting the toner replenishment amount. The second control means controls the image density of the output image based on the control result of the first control means. The target value of the density of the reference density pattern is adjusted, and the control of the second control means is executed during the control interval of the first control means.

In order to achieve the above object, the invention of claim 22 forms an electrostatic latent image corresponding to a plurality of color image patterns sequentially on a single photosensitive member or on a plurality of photosensitive members, After developing the electrostatic latent image, in a color image forming apparatus for sequentially transferring on a recording material or an intermediate transfer member,
Forming a first reference density pattern of each color on the photoreceptor, irradiating the first reference density pattern with detection light, and detecting reflected light thereof, thereby obtaining a density of the first reference density pattern; First detecting means for detecting, and controlling the toner density by adjusting the toner supply amount so that the density of the first reference density pattern detected by the first detecting means becomes a target value. A first control means for controlling the image density of the output image by using the second reference density pattern of each color on the photosensitive member, and the second reference density pattern on a recording material conveyance body or an intermediate transfer body. After transferring the second reference density pattern, by detecting the reflected light or transmitted light by irradiating the second reference density pattern with detection light, the second detection means for detecting the density of the second reference density pattern, Detected by the second detection means Second control means for controlling the image density of the output image by correcting and controlling the gradation correction means so that the density of the second reference density pattern obtained becomes the target value. Adjusting the target value of the density of the second reference density pattern based on the control result of the control means, and causing the control of the second control means to be executed during the control interval of the first control means. It is characterized by.

In order to achieve the above object, a twenty-third aspect of the present invention provides a method for forming a first reference image on a photoreceptor and detecting the density of the first reference image formed on the photoreceptor. A first detection step, a first control step of controlling the image forming apparatus based on the detection result detected in the first detection step, and forming a second reference image on the photoconductor, A second detection step of transferring the second reference image formed thereon onto a transfer body and detecting the density of the second reference image transferred on the transfer body; and the second detection And a second control step of controlling the image forming apparatus based on the detection result detected in the step, wherein the control of the second control step is adjusted based on the control result in the first control step. It is characterized by.

To achieve the above object, a twenty-fourth aspect of the present invention is to form a first reference image on a photoreceptor and detect the density of the first reference image formed on the photoreceptor. A first detection step, a first control step of controlling the image forming apparatus based on the detection result detected in the first detection step, and forming a second reference image on the photoconductor, A second detecting step of detecting the density of the second reference image transferred onto the transfer body after transferring the second reference image formed thereon onto a transfer body; and A second control step of controlling a correction value of the gradation correction step of the image forming apparatus based on a detection result detected by the detection step, wherein the second control step is performed based on a control result of the first control step. The control of the second control step is adjusted.

In order to achieve the above object, according to a twenty-fifth aspect of the present invention, an electrostatic latent image corresponding to a plurality of color image patterns is formed on a single photoconductor sequentially or on a plurality of photoconductors. In the image forming method of the color image forming apparatus for sequentially transferring the electrostatic latent image onto a recording material or an intermediate transfer member after developing the electrostatic latent image, a first reference density pattern of each color is formed on the photosensitive member. Then, by irradiating the first reference density pattern with detection light and detecting its reflected light,
A first detection step of detecting a density of the first reference density pattern, and a density of the first reference density pattern detected in the first detection step is a target value.
A first control step of controlling the image density of the output image by controlling the toner density by adjusting the toner supply amount, and forming a second reference density pattern of each color on the photoreceptor, and conveying the recording material. After transferring the second reference density pattern onto a body or an intermediate transfer member, the second reference density pattern is irradiated with detection light to detect reflected light or transmitted light, thereby obtaining the second reference density pattern. A second detection step of detecting and detecting the density of the density pattern; and adjusting a toner supply amount such that the density of the second reference wetness pattern detected in the second detection step becomes a target value. A second control step of controlling the image density of the output image by controlling the toner density by using the control means, and based on the control result of the first control step, the target of the density of the second reference density pattern. value Adjusted, characterized in that to execute the control of the second control step during the interval of the control of the first control step.

In order to achieve the above object, according to a twenty-sixth aspect of the present invention, an electrostatic latent image corresponding to an image pattern of a plurality of colors is formed on a single photoconductor sequentially or on a plurality of photoconductors. After the electrostatic latent image is developed, in a color image forming apparatus for sequentially transferring on a recording material or an intermediate transfer member,
Forming a first reference density pattern of each color on the photoreceptor, irradiating the first reference density pattern with detection light, and detecting reflected light thereof, thereby obtaining a density of the first reference density pattern; A first detecting step of detecting, and controlling a toner density by adjusting a toner supply amount such that a density of the first reference density pattern detected in the first detecting step becomes a target value. A first control step of controlling an image density of an output image by using a second reference density pattern of each color on the photosensitive member, and a second reference density pattern on a recording material transporting body or an intermediate transfer body. Transferring the second reference density pattern, and irradiating the second reference density pattern with detection light to detect reflected light or transmitted light thereof, thereby detecting a density of the second reference density pattern, The second A second control step of controlling the image density of the output image by correcting and controlling the gradation correction step so that the density of the second reference density pattern detected in the detection step becomes a target value. Adjusting the density target value of the second reference density pattern based on the control result of the first control step, and controlling the second control step during the control interval of the first control step. Is executed.

In order to achieve the above object, according to a twenty-seventh aspect of the present invention, an electrostatic latent image corresponding to a plurality of color image patterns is formed on a single photoreceptor sequentially or on a plurality of photoreceptors. After developing the electrostatic latent image, a recording medium recorded with an image forming control program for controlling by a computer a color image forming apparatus that sequentially transfers onto a recording material or onto an intermediate transfer body, The control program causes the computer to form a first reference density pattern of each color on the photoreceptor, irradiates the first reference density pattern with detection light, and detects reflected light thereof.
The density of the first reference density pattern is detected. As a first control, the toner supply amount is adjusted by adjusting the toner supply amount so that the detected density of the first reference density pattern becomes a target value. By controlling the image density of the output image, a second reference density pattern of each color was formed on the photosensitive member, and the second reference density pattern was transferred onto a recording material transporting body or an intermediate transfer body. Thereafter, by irradiating the second reference density pattern with detection light and detecting the reflected light or transmitted light thereof, the density of the second reference density pattern is detected. The image density of the output image is controlled by controlling the toner density by adjusting the toner supply amount so that the density of the second reference density pattern becomes the target value. Based Te, wherein to adjust the target value of the concentration of the second reference density pattern, characterized in that to execute the second control during the interval of the first control.

In order to achieve the above object, according to a twenty-eighth aspect of the present invention, an electrostatic latent image corresponding to a plurality of color image patterns is formed sequentially on a single photosensitive member or on a plurality of photosensitive members. A recording medium recording an image control program for controlling by a computer a color image forming apparatus that sequentially transfers the image on a recording material or an intermediate transfer member after developing the electrostatic latent image, wherein the control program is By causing a computer to form a first reference density pattern of each color on the photoreceptor, irradiating the first reference density pattern with detection light and detecting reflected light thereof, the first reference density pattern is formed. The density of the pattern is detected, and the first control is to control the toner density by adjusting the toner supply amount such that the detected density of the first reference density pattern becomes a target value. To control the image density of the force image, to form a second reference density pattern of each color on the photosensitive body,
After transferring the second reference density pattern onto a recording material conveying body or an intermediate transfer body, the second reference density pattern is irradiated with detection light to detect reflected light or transmitted light, thereby obtaining the second reference density pattern. 2 is detected, and as a second control, the tone correction step is corrected and controlled so that the detected density of the second reference density pattern becomes a target value. Controlling the image density; adjusting the target value of the density of the second reference density pattern based on the control result of the first control;
The second control is executed during the control interval of the control.

[0035]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In the following, an embodiment in which the present invention is applied to an electrophotographic color copying machine having a plurality of drums will be described. However, the present invention is not limited to this, and various types of electrophotographic copying machines, printers, It goes without saying that the present invention can be applied to image forming apparatuses other than the mono-color type and electrophotography.

[Hardware Configuration] FIG. 1 shows an example of the configuration of a color copying machine according to an embodiment of the present invention. The full-color image forming operation will be described with reference to FIG.

A document 101 placed on a document table glass 102 of the reader unit A is irradiated by a light source 103 and is imaged on a CCD sensor 105 via an optical system 104. C
Red (R) arranged in three rows,
Green (G) and blue (B) CCD line sensor groups generate R, G, and B color component signals for each line sensor.

By scanning the reading optical system unit having these components 103 to 105 in the direction of the arrow in the drawing, the image of the original 101 is converted into an electric signal data sequence for each line. A reference white plate 106 for determining the white level of the CCD sensor 105 and shading the CCD sensor 105 in the thrust direction is disposed at one corner of the surface of the platen glass 101.

The image signal obtained by the CCD sensor 105 is subjected to shading correction and conversion to a signal of yellow (Y), cyan (C), magenta (M), black (Bk) by the reader image processing unit 108. After the image processing is performed, it is sent to the printer unit B, and the printer control unit 109 performs processing such as pulse width modulation.

FIG. 2 shows the configuration of the image processing unit 108 of the reader unit A according to the present embodiment along the flow of image signal processing.

As shown in FIG. 2, an image signal output from the CCD sensor 105 is input to an analog signal processing unit 201 of the image processing unit 108, where gain adjustment and offset adjustment are performed, and then A / D ( An analog / digital converter 202 converts each color signal into 8-bit digital image signals R1, G1, and B1. Thereafter, the image signal is input to a shading correction unit 203, and a known shading correction is performed using a read signal of the reference white plate 106 for each color.

Image signal R subjected to shading correction
2, G2 and B2 are input to the line delay circuit 204. Since the line sensors of the CCD sensor 105 are arranged at a predetermined distance from each other, the line delay circuit 204 corrects a spatial shift in the sub-scanning direction.

The image signals R 3, G 3, and B 3 whose spatial displacement in the sub-scanning direction has been corrected are input to the input masking section 205. The input masking unit 205 includes the CCD sensor 10
The read color space determined by the spectral characteristics of the R, G, B filters (not shown) of No. 5 is represented by NTSC (National Television Sy).
stem Committee) to convert to the standard color space,
A 3 × 3 matrix operation is performed.

Next, the NTSC signals R4, G4, B4
Is a light quantity / density converter (LOG converter: logarithmic converter) 2
Enter 06. The light quantity / density conversion unit 206 is a look-up table (LU) of a RAM (random access memory).
T), and the luminance signals of R4, G4 and B4 are Y
It is converted into a density signal of 0, M0, C0.

The density signals of Y 0, M 0, and C 0 become density signals of Y 1, M 1, and C 1 via a line delay memory 207 and are input to a masking and UCR (under color removal) circuit 208. The masking and UCR circuit 208 extracts a black signal (Bk) from the input three primary color signals of Y1, M1, and C1, and further performs an operation of correcting the color turbidity of the recording color material in the printer unit B, and performs an operation of Y2. , M2, C2, and Bk2 are sequentially converted into a predetermined bit width (8 bits) for each reading operation.
To output.

The signals Y2, M2, C2, and Bk2 are input to a spatial filter processing unit (output filter) 209. The spatial filter processing unit 209 performs edge enhancement or smoothing processing. The image memory unit 210 at the next stage temporarily stores the Y3, M3, C3, and Bk3 processed as described above, and synchronizes the LUT with the image formation of the printer unit B.
(Lookup table) 209.

The LUT 211 performs density correction in the reader unit A so as to match the ideal gradation characteristics of the printer unit B. Signals Y5, M5, C output from LUT 211
5, Bk5 are sequentially sent to the printer control unit 109 of the printer unit B via the connection line.

A pattern generator 212 is mounted on the image forming apparatus, and a specific pattern is registered in the pattern generator 212. The specific pattern is directly transmitted to a pulse width modulator (PWW) 216 as a signal. You can pass it.

The thus processed Y5, M5, C5,
The Bk5 image signal is sent to the printer control unit 109.

Next, the printer section B will be described. The image signal sent to the printer control unit 109 is pulse width modulated by a pulse width modulator (PWW) 216, and the laser driver 217 and the semiconductor lasers 311, 312, 313,
The laser beam is converted by 14 into a laser beam.

In FIG. 1, reference numeral 110 denotes a polygon scanner (rotating polygon mirror scanner) which scans the laser beam to form photosensitive drums 121 to 1 of image forming units 120 to 150.
Irradiate 51.

Reference numeral 120 denotes a yellow (Y) image forming unit,
Reference numeral 30 denotes a magenta (M) image forming unit, 140 denotes a cyan (C) image forming unit, and 150 denotes a black (Bk) image forming unit, each of which forms an image of a corresponding color. Since these image forming units 120 to 150 have substantially the same configuration, the details of the Y image forming unit 120 will be described below, and the description of the other image forming units will be omitted.

In the Y image forming section 120, a photosensitive drum 121 forms an electrostatic latent image on the surface thereof by a laser beam from the polygon scanner 110. 122
Is a primary charger for charging the surface of the photosensitive drum 121 to a predetermined potential to prepare for formation of an electrostatic latent image. A developing unit 123 develops the electrostatic latent image on the photosensitive drum 121 to form a toner image. A transfer blade 124 discharges from the back of the transfer belt 111 to transfer the toner image on the photosensitive drum 121 to a recording paper or the like on the transfer belt 111.

After the transfer, the surface of the photosensitive drum 121 is cleaned by the cleaner 127, the charge is removed by the auxiliary charger 128, and the residual charge is erased by the pre-exposure lamp 129. A charge is obtained.

The recording paper or the like onto which the toner image has been transferred is conveyed by a transfer belt 111. Thereafter, the toner images of the respective colors formed by the respective image forming units are sequentially transferred in the order of M, C, and Bk. A color image is formed on the surface. The recording paper or the like that has passed through the Bk image forming section is easily discharged from the transfer belt 111.
After the charge is removed at 12, the transfer belt 111 is separated.

The separated recording paper or the like is charged with a pre-fixing charger 11 in order to supplement the toner attraction force and prevent image disturbance.
After the charging in step 3, the fixing device 114 fixes the toner image. On the other hand, the transfer belt 111 from which the recording paper is separated
Is neutralized by the transfer belt static elimination charger 115.
After being cleaned by the belt cleaner 116, preparations are made to adsorb the recording paper again.

[First Embodiment] In the first embodiment of the present invention, in order to form a full-color image with stable density and gradation, the photosensitive drums 121, 131, and 14 are used.
1 and 151, a first reference density pattern of each color is formed, and the first reference density pattern is irradiated with detection light.
By detecting the reflected light, the density of the first reference density pattern is detected, and the toner replenishment amount of the developing device 123 is determined so that the detected density of the first reference density pattern becomes a target value. There is a first density control mode for controlling the image density of the output image by adjusting the toner density by adjusting.

The photosensitive drums 121, 131, 141,
After forming a second reference density pattern of each color on the transfer belt 111 and transferring the second reference density pattern to the transfer belt 111, the second reference density pattern is irradiated with detection light, and the reflected light is detected to detect the second reference density pattern. Detecting the density of the reference density pattern 2;
The second density for controlling the image density of the output image by controlling the toner density by adjusting the toner supply amount of the developing device 123 so that the detected density of the second reference density pattern becomes the target value. It has a control mode. Then, the target value of the density of the second reference density pattern is adjusted according to the state of the color copying machine based on the control result of the first density control mode, and then during the control interval of the first density control mode. Is characterized in that control of the second density control mode is executed. The details of this control will be described below.

First, control in the first density control mode will be described.

FIG. 3 is a flowchart showing a control procedure in the first density control mode. First, the reader 101 reads the document 101 (step S11).
Subsequently, a copy operation is started in the printer unit B (step S12). Thereafter, the copying for the set number of sheets is completed (step S13).

After copying, the photosensitive drums 121 and 13
A first reference density pattern (patch image) of each color is formed on 1, 141, 151, and the first reference density pattern is irradiated with detection light, and the reflected light is detected to detect the first reference density pattern. Is measured (step S14). The measured toner density measured value is compared with a reference value as a target value, and a measured value b−a reference value b ′ is calculated (step S15).

The calculation result of the measured value b-the reference value b 'is converted into an excessive or insufficient toner amount for keeping the patch image density constant (step S16). The toner supply amount is determined based on the converted excess or insufficient toner amount (step S1).
7). The toner supply of the developing device 123 is performed with the determined toner supply amount (step S19).

First, the developing process according to the present embodiment will be described using the yellow color (Y) as an example. Y developing device 12
3 is shown in FIG. As shown in FIG. 4, the developing device 123 is disposed so as to face the photosensitive drum 121, and the latent image on the photosensitive drum 121 is transported to a developing area facing the photosensitive drum 121 as the photosensitive drum 121 rotates. . Then, the developer is used for developing the latent image on the photosensitive drum 121 in the developing area. In order to improve the development efficiency, that is, the toner application rate to the latent image, a development bias voltage in which a DC voltage is superimposed on an AC voltage is applied from a power supply 37 to the development sleeve 34.

Since the toner concentration of the developer 44 in the developing device 123 is reduced by developing the electrostatic latent image,
Developability decreases. Further, a change in the developability also occurs due to a change in the surrounding environment, repetition of the development process, and the like, and as a result, a change in image density and gradation occurs.

FIG. 5 is a diagram showing image density detection and toner supply. In the present embodiment, when performing the first density control mode, the photosensitive drums 121 and 13 are used in order to suppress the fluctuations in the image density and gradation and to perform stable control.
1, 141, 151, a test pattern is formed, and the test pattern is formed on the photosensitive drums 121, 131, 141,
Irradiation is performed by an LED 702 which is a light-emitting unit opposed to the light-receiving unit 151, and reflected light is reflected by a photodiode 703 which is a light-receiving unit
, The density of the test pattern is detected, and control is performed to adjust the toner density of the developing device 123 in accordance with the detection result.

This image density detecting sensor 701 is shown in FIG. 5 without increasing the size of the apparatus, securing the installation space for the developing unit 123, and avoiding contamination by free toner from the developing unit 123. As shown, it is provided at a later stage of the transfer process.

Next, a control procedure in the first density control mode will be described. Photosensitive drum 1 in first density control mode
The density detection control on 21, 131, 141, 151 is performed after the image forming process, and the photosensitive drums 121, 131,
A patch image (test pattern) is formed on 141 and 151 as a reference image for density detection.

That is, as shown in FIG. 2, a patch image signal from the pattern generator 212 for generating a patch image signal having a signal level corresponding to a predetermined density is supplied to the pulse width modulation circuit 216, A laser drive pulse having a pulse width corresponding to the predetermined density is generated. The laser drive pulse is supplied to the semiconductor laser 311 and the semiconductor laser 311
Is emitted for a time corresponding to the pulse width, and the photosensitive drum 121 is scanned. As a result, a patch electrostatic latent image corresponding to the predetermined density is formed on the photosensitive drum 121, and the patch electrostatic latent image is
To develop.

The density of the patch image is set to a density at which the development characteristics represented by the characteristic diagram of FIG. 6 can be most easily controlled. As a result, not only the image density but also the gradation can be controlled to desired characteristics by the control described below. In FIG. 6, the vertical axis represents the image density, and the horizontal axis represents the relative photosensitive drum surface potential (V). In the figure, the patch image density is shown as the target image density. A solid line L is an example of an ideal characteristic, and a broken line N is an example of a characteristic when correction is to be performed.

Next, the patch image (toner image) obtained as described above is irradiated with light from an LED 702, which is a light emitting portion of a density detection sensor 701 for density detection control on a photosensitive drum, and the reflected light is emitted. Photodiode 7 as light receiving unit
At 03, the actual image density of the patch image is detected. The detected patch image density corresponds to the toner density of the developer 643 in the developing device 123.

As shown in FIG. 5, an output signal S-SIG-Y for detecting the actual patch image density obtained from the photodiode 703 is supplied to one input of a comparator 704. A reference signal S-INIT-Y corresponding to a specified density (initial density) of the patch image is input from the reference voltage signal source 705 to the other input of the comparator 704. The comparator 704 compares the patch image density with the initial image density, obtains the density difference, and supplies an output signal S-CAL-Y of the density difference to the CPU 214. The output signal S-CAL-Y of the density difference is used for controlling toner supply to the developer in the developing device 123.

In general, as the toner density of the developer increases, the image density increases, and conversely, the image density at which the toner density of the developer decreases decreases. In the present embodiment,
Based on the output signal S-CAL-Y of the density difference between the patch image density and the initial image density output by the density detection control on the photosensitive drum in the first density control mode, the developing device 123
The image density is maintained at a desired value by adjusting the amount of toner supplied to the developer inside.

As described above, the density detection on the photosensitive drum in the first density control mode is performed after the image forming step of the patch image. The above image density detection sensor 7
5, the transfer belt 111 is separated from the photosensitive drum 121 when the density detection control on the photosensitive drum is performed by being disposed at the position after the transfer step as shown in FIG. Therefore, during continuous image formation, such as when copying the same image a plurality of times, the transfer belt 11 is interposed between image formations.
1 cannot be separated from the photosensitive drum 121, so that the on-photosensitive-drum detection control is performed after the image forming process is completed.

In this embodiment, during a series of image forming steps such as continuous image formation, that is, during an interval for performing the density detection control on the photosensitive drum, the transfer belt in the second density control mode described below is used. By performing the upper density detection control and controlling the toner density of the developer during continuous image formation, the image density is kept stable.

Next, control in the second density control mode will be described.

FIG. 7 is a flowchart showing a control procedure of the second density control mode according to the present invention. First, the reader 101 reads the original 101 (step S2).
1) Subsequently, a copy operation is started in the printer unit B (step S22). Prior to the first image forming step of the continuous image forming step, a patch image as a second reference density pattern is formed directly on the transfer belt 111 (step S23).

In the density detection control on the transfer belt, the step of forming a patch image as a reference image for density detection on the photosensitive drum 121 is similar to the density detection control on the photosensitive drum in the first density control mode described above. It is. The patch image on the photosensitive drum 121 is directly transferred to the transfer belt 111, and its density is detected by an image density detection sensor 160 installed opposite to the transfer belt 111.

As shown in FIG. 1, the image density detecting sensor 1
Reference numeral 60 denotes image forming units 120, 130, 140, and 1 for each color.
It is arranged after 50. The configuration of the image density detection sensor 160 is the same as that of the image density detection sensor 701 used for the density detection control on the photosensitive drum.

The control for detecting the density on the transfer belt in the second density control mode is performed during a plurality of image forming steps, as shown in FIG. A patch electrostatic latent image having a predetermined image signal level is formed on each of the photosensitive drums 121 and is directly transferred onto the transfer belt 111.

The density of the patch image is set to a density at which the development characteristics can be most easily controlled, similarly to the density detection control on the photosensitive drum.

Next, the patch image (toner image) obtained as described above is irradiated with light from an LED which is a light emitting portion of the image density detection sensor 160 for the density detection control on the transfer belt, and the reflected light is received. The light is received by a photodiode as a unit, and the actual image density of the patch image is detected.

FIG. 8 schematically shows a patch image forming sequence at the time of continuous image formation with reference to the transfer belt 111. As shown in FIG. 8, in the present embodiment, prior to the first image forming step of the continuous image forming step, a patch image is directly formed on the transfer belt 111 (steps S21 to S23), and the image density detection sensor 16
The first output signal B-SIG-Y that detects the actual patch image density output from the photodiode 0 (step S24) is used as the reference density of the patch image by the CPU.
Is stored in the RAM 215 via the RAM 214 (step S2
5).

Next, as shown in FIG. 8, one copy image is formed in a normal image forming process (step S2).
6).

Thereafter, after each image formation in the continuous image formation process, a patch image is formed on the transfer belt 111 (step S27), and the density of each patch image is detected by the photodiode of the image density detection sensor 160 (step S27). S28), the respective detection output signals B-SIG-Y
Is supplied to one input of a comparator 161 (see FIG. 2). The other input of the comparator 161 is supplied from a reference voltage signal source 162 (see FIG. 2) with a reference reference density determined based on the reference reference density stored in the RAM 215 every time a continuous patch image is formed. Reference signal B-IN corresponding to
IT-Y has been input. The comparator 161 compares the patch image density with the reference reference density to determine the density difference, and supplies an output signal B-CAL-Y of the density difference to the CPU 214 (step S29).

The output signal B-CAL-Y of the density difference is
The CPU 214 controls toner supply to the developer in the developing device 123 during continuous image formation. That is, during continuous image formation, toner is supplied to the developer in the developing device 123 based on the output signal B-CAL-Y of the density difference output by the density detection control on the transfer belt, so that the desired image density is obtained. The value is kept. That is, the CPU 214
Based on the calculated density difference output signal B-CAL-Y, it is converted into an excessive or insufficient toner amount for keeping the patch image density constant, and a toner replenishing amount is determined based on the converted excessive or insufficient toner amount. Developing device 12 with the supplied toner supply amount.
The toner supply of No. 3 is performed (step S30).

Thereafter, it is determined whether or not copying for the set number of sheets has been completed. If not completed, the process returns to step S23 to repeat the above-described processing of the density detection control on the transfer belt to copy the set number of copies. When finished (step S3
1), the density detection control on the photosensitive drum, which is the first density control mode shown in FIG. 3, is executed (step S32).

As described above, in this embodiment, first, the image density is controlled by the density detection control on the photosensitive drum which is the first density control mode. This makes it possible to effectively correct a change in image density due to environmental fluctuations and durability fluctuations occurring over a relatively long span.

Further, when performing the density detection control on the transfer belt in the second density control mode, the desired image density is substantially obtained by the density detection control on the photosensitive drum in the first density control mode. By determining the reference reference density, which is the target value of the density control on the transfer belt, for each continuous image forming step, it is possible to control the image density during the continuous image forming step extremely stably. In other words, by determining the reference reference density for each successive image formation, the density on the photosensitive drum is hardly affected by a change over time such as dirt or scratches on the transfer belt 111 or a characteristic change of the image density detection sensor 160. The state of image formation controlled by the detection control can be maintained.

[Second Embodiment] Next, a second embodiment of the present invention will be described. The configuration and image forming process of the color copying machine of the present embodiment are the same as those of the first embodiment. The density detection control on the photosensitive drum, which is the first density control mode, is the same as that in the first embodiment.

FIG. 9 is a flowchart showing a control procedure of the second density control mode in this embodiment. In the present embodiment, the output signal BC of the density difference output by the density detection control on the transfer belt in the second density control mode.
The image density is kept at a desired value by correcting the latent image contrast potential by changing the output intensity of the laser beam based on AL-Y (step S30).
-1). Other procedures are the same as those in FIG.

More specifically, in the density detection control on the transfer belt, as in the first embodiment, prior to the first image forming step of the continuous image forming step (step S2).
1, S22) A patch image as a second reference density pattern is formed (Step S23), and an actual patch image density from the photodiode of the image density detection sensor 160 is detected (Step S24). First output signal BS
The CPU 21 uses IG-Y as the reference reference density of the patch image.
4 in the RAM 215 (step S2).
5). Thereafter, after forming a copy image (step S2)
6), after each image formation in the continuous image formation process, a patch image is formed on the transfer belt 111 (step S27), and each patch image density is detected by the image density detection sensor 160 (step S28), and each detection is performed. Output signal B-
SIG-Y is supplied to one input of a comparator 161. The other input of the comparator 161 receives, from the reference voltage signal source 162, a reference signal B-INIT-Y corresponding to a reference reference density determined for each successive image formation of patch images. The comparator 161 compares the patch image density with the reference reference density to obtain a density difference, and supplies an output signal B-CAL-Y of the density difference to the CPU 214 (step S29). The latent image potential contrast during the continuous image formation is corrected by changing the output intensity of the laser beam based on the density difference output signal B-CAL-Y (step S30-1).

That is, during continuous image formation, the ROM
The output intensity (hereinafter referred to as laser power) of the laser beam from the output signal B-CAL-Y of the density difference output by the density detection control on the transfer belt with reference to a conversion table (not shown) stored in the 218. Calculate the correction amount. At this time, the correction amount of the laser power is adjusted in consideration of the time difference determined by the distance between the image exposure position and the patch density detection position on the transfer belt. Also, during continuous image formation, constant toner supply is performed based on the integrated amount of image data.

As described above, in the present embodiment, as in the first embodiment, the density detection control on the photosensitive drum, which is the first density control mode, causes environmental fluctuations and durability fluctuations occurring over a relatively long span. The image density change can be effectively corrected, and when performing the density detection control on the transfer belt in the second density control mode, the density detection control on the photosensitive drum in the first density control mode By determining the reference reference density, which is the target value of the density control on the transfer belt, in the state where the image density is almost obtained for each continuous image forming step, the image density during the continuous image forming step is extremely stable. Can be controlled.

In addition, in the present embodiment, the laser power during the continuous image forming process is corrected to temporarily change the sensitivity of the photosensitive drum due to the continuous image formation, and the power due to the temperature rise of the laser. The image density controlled by the density detection control on the photosensitive drum can be maintained, including factors other than the change in toner density, such as a change.

[Third Embodiment] FIGS. 1 to 7 show:
The same applies to the third embodiment of the present invention.

In this embodiment, a first reference density pattern of each color is formed on the photosensitive member in order to form a full-color image having a stable density and gradation, and the detection light is applied to the first reference density pattern. And the reflected light is detected to detect the density of the first reference density pattern. The toner replenishment amount is adjusted so that the detected density of the first reference density pattern becomes the target value. Controlling the image density of the output image by adjusting the toner density;
A density control mode, a second reference density pattern of each color is formed on a photoreceptor, transferred to a transfer belt, and then the detection light is applied to the transferred second reference density pattern on the transfer belt. By detecting the reflected light, the density of the second reference density pattern is detected, and the density correction LUT 211 of FIG. 2 is corrected so that the detected density of the second reference density pattern becomes a target value. A second density control mode for controlling the image density of the output image.
The density target value of the second reference density pattern in the second density control mode is adjusted according to the state of the color copying machine according to the control result of the density control mode, and the control interval of the first density control mode is adjusted. During this period, the control in the second density control mode is executed.

Hereinafter, control contents in the third embodiment of the present invention will be described in detail.

First, control in the first density control mode will be described. As described above in the first embodiment of the present invention, the control for detecting the density on the photosensitive drum is performed after the image forming process. As shown in FIG. 5, since the image density detection sensor 701 is disposed at a position after the transfer process, the transfer belt 111 is separated from the photosensitive drum 121 when performing the density detection control on the photosensitive drum. . Therefore, during continuous image formation such as when a plurality of copies of the same image are made, the transfer belt 111 cannot be separated from the photosensitive drum 121 between image formations. Therefore, the density detection control on the photosensitive drum is performed after the image forming process is completed.

In the present embodiment, during a series of image forming steps such as continuous image formation, that is, during an interval for performing the density detection control on the photosensitive drum, the second density control mode described below is set. The density detection control on the transfer belt is executed, and the correction control of the image density during the continuous image formation is performed to keep the image density stable.

Next, control in the second density control mode will be described. In the present embodiment, unlike the first embodiment of the present invention, the density of the patch image is set to a density at which the gradation characteristic can be most easily controlled. Specifically 128
The density patch is formed by the level signal (the maximum density in this case is 255 levels).

FIG. 10 schematically shows a patch image forming sequence at the time of continuous image formation with reference to the transfer belt 111. In the present embodiment, the patch image is formed prior to the first image forming step of the continuous image forming step, and the first output of detecting the actual patch image density from the photodiode of the image density detecting sensor 160 in FIG. The signal B-SIG-Y is stored in the RAM 215 via the CPU 214 as the reference density of the patch image. Thereafter, after each image formation in the continuous image formation process, a patch image is formed on the transfer belt 111, the density of each patch image is detected by the photodiode of the image density detection sensor 160, and each detection output signal B-SIG -Y
Is supplied to one input of a comparator 161. The other input of the comparator 161 receives, from the reference voltage signal source 162, a reference signal B-INIT-Y corresponding to a reference reference density determined for each successive image formation of patch images. The comparator 161 compares the patch image density with the reference density to determine the density difference, and outputs the density difference output signal BC.
AL-Y is supplied to the CPU 214. The CPU 214 uses this density difference output signal B-CAL-Y for LUT correction control during continuous image formation. That is, during the continuous image formation, the CPU 214 sets the L level based on the density difference output signal B-CAL-Y output by the density detection control on the transfer belt.
By correcting the contents of the UT 211, the image density and the gradation characteristics are maintained at desired values.

Next, a method of correcting the LUT 211 will be described.
In the ROM 218, a plurality of LUTs 211 (look-up tables) for correcting the LUT 211 according to the density correction amount (or the value of the density difference output signal B-CAL-Y) are stored in advance. The LUTs for correcting the plurality of LUTs 211 are composed of a total of ten correction LUTs, five on the density-up side and five on the density-down side.

FIG. 11 shows the contents of the correction LUT. These correction LUTs are set so that the correction amount becomes maximum near 128 levels, but can be set arbitrarily according to the characteristics of the image forming apparatus. As described above, the density difference output signal B-CAL-Y
Is sent to the CPU 214. The CPU 214 calculates the density difference B−
In accordance with the value of CAL-Y, an appropriate correction LUT is selected from the above correction LUTs, and the already set LUT 211
New LUT by multiplying this selected correction LUT
Is set as the LUT 211. By performing the next image formation using this new LUT, the image density and gradation characteristics during continuous image formation can be corrected.

As described above, in the present embodiment, the image density is controlled by the density detection control on the photosensitive drum which is the first density control mode. This makes it possible to effectively correct a change in image density due to environmental fluctuations and durability fluctuations occurring over a relatively long span. Further, when performing the density detection control on the transfer belt which is the second density control mode,
In a state where a desired image density is almost obtained by the density detection control on the photosensitive drum which is the first density control mode,
The reference reference density, which is the target value of the density control on the transfer belt, is determined for each continuous image forming step, and the LUT 211 is corrected so that the patch image density becomes the reference reference density. It is possible to control image density and gradation characteristics extremely stably.

That is, in the present embodiment, by determining the reference reference density for each successive image formation, a change with time such as dirt and scratches on the transfer belt 111 and the density detection sensor 1 are determined.
It is possible to maintain the state of image formation controlled by the on-photosensitive-drum density detection control without being substantially affected by the fluctuation of characteristics of the photosensitive drum 60.

[Fourth Embodiment] The structure and image forming process of a color copying machine according to a fourth embodiment of the present invention are described in the first embodiment.
This is the same as the embodiment. The density detection control on the photosensitive drum, which is the first density control mode, is the same as that in the first embodiment.

FIG. 12 shows a patch image forming sequence when a continuous image is formed in this embodiment. FIG.
As shown in FIG. 1, in the present embodiment, the transfer belt 11
A plurality of patch images for each color are formed in parallel on each color. More specifically, in the present embodiment, four levels of patch images of image data levels 32, 64, 128, and 192 are formed, and a plurality of density detection sensors 160 on the transfer belt are provided, so that the respective patch image densities are obtained. Is detected. Output signals B-CAL-Y1 to B-C of density differences corresponding to the patch image densities of each level output by the density detection control on the transfer belt which is the second density control mode.
By controlling the gradation correction LUT 211 based on AL-Y4, the image density and the gradation characteristics are maintained at desired values.

Next, a method of correcting the LUT 211 will be described.
As described above, the comparator 161 calculates the density difference output signals B-CAL-Y1 to B-CAL-Y4,
When sent to the PU 214, the CPU 214 determines the density difference BC.
Correction L based on the values of AL-Y1 to B-CAL-Y4
Create a UT. FIG. 13 shows an example of a correction LUT created by the CPU 214, and B-CAL-
The correction table is formed by linear interpolation between four points corresponding to the values of Y1 to B-CAL-Y4 and the maximum and minimum data points.

Next, the CPU 214 sets a new LUT as the LUT 211 by multiplying the already set LUT 211 by the created correction LUT. This new L
By performing the next image formation using the UT, the image density and gradation characteristics during continuous image formation can be corrected.

As described above, in the present embodiment, as in the third embodiment, the density detection control on the photosensitive drum, which is the first density control mode, causes environmental fluctuations and durability fluctuations occurring in a relatively long span. The image density change can be effectively corrected, and when performing the density detection control on the transfer belt in the second density control mode, the density detection control on the photosensitive drum in the first density control mode By determining the reference reference density, which is the target value of the density control on the transfer belt, in a state where the image density is substantially obtained for each continuous image forming process, the gradation correction LUT is executed during the continuous image forming process. By performing the correction control, it is possible to control the image density and the gradation characteristic during the continuous image forming process very stably.

[Fifth Embodiment] In the first to fourth embodiments of the present invention, in the control of the second density control mode, a test pattern is formed directly on the transfer belt 111 to detect the image density. The case where the formed toner density is detected by the sensor 160 and the density of the formed image is controlled according to the detected density has been described. However, the present invention is not limited to this. Forming a test pattern on an intermediate transfer member (not shown) arranged in a predetermined direction, and detecting the formed toner density by an image density detection sensor (not shown) arranged opposite to the intermediate transfer member. May be configured to execute the density control.

Sixth Embodiment In the first to fourth embodiments of the present invention, a four-drum type full-color copying machine using four photosensitive drums has been exemplified, but the present invention is not limited to this. The present invention can be applied to various image forming apparatuses irrespective of the type, including other types of full-color copying machines, mono-color / multi-color copying machines, copying machines other than electrophotography, and image reading devices such as scanners. .

[Other Embodiments] Even if the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, and the like), a device composed of one device (for example, For example, the present invention may be applied to a copying machine, a facsimile machine, and the like.

Further, it is an object of the present invention to provide a recording medium (storage medium) recording software program codes for realizing the functions of the above-described embodiments to a system or an apparatus, and to provide a computer for the system or the apparatus. Needless to say, the present invention is also achieved when the CPU (or the CPU or the MPU) reads out and executes the program code stored in the recording medium.

In this case, the program code itself read from the recording medium realizes the functions of the above-described embodiment, and the recording medium on which the program code is recorded constitutes the present invention.

Examples of a recording medium for recording the program code and variable data such as a table include a floppy disk (FD), hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, A nonvolatile memory card (IC memory card), a ROM, or 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. It goes without saying that an operating system) may perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

[0119]

As described above, according to the present invention,
In an image forming apparatus such as a copying machine or a printer of an electrophotographic system or an electrostatic recording system, a reliable and simple image density detecting means is used without increasing the size of the apparatus more than necessary. In addition, the fluctuation of the output image density can be effectively corrected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an internal configuration of a color copying machine according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration example of a reader unit according to the present invention.

FIG. 3 is a flowchart illustrating a control procedure in a first density control mode according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing a configuration example of a developing device of the color copying machine of FIG. 1;

FIG. 5 is a schematic diagram showing image density detection and toner supply of the color copying machine of FIG. 1;

FIG. 6 is a graph showing the relationship between surface potential and image density.

FIG. 7 is a flowchart illustrating a control procedure in a second density control mode according to the first embodiment of the present invention.

FIG. 8 is a schematic diagram showing a patch image formation sequence at the time of continuous image formation in a second density control mode according to the first embodiment of the present invention.

FIG. 9 is a flowchart illustrating a control procedure of a second density control mode according to the second embodiment of the present invention.

FIG. 10 is a schematic diagram showing a patch image forming sequence at the time of forming a continuous image according to the third embodiment of the present invention.

FIG. 11 is a characteristic diagram illustrating a plurality of correction LUTs according to a density correction amount according to the third embodiment of the present invention.

FIG. 12 is a schematic diagram illustrating a patch image formation sequence during continuous image formation according to a fourth embodiment of the present invention.

FIG. 13 is a characteristic diagram illustrating an example of a correction LUT created in a fourth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 101 original document 102 original platen glass 105 CDD sensor 108 reader image processing unit 109 printer control unit 110 polygon scanner 111 transfer belt 160 image density detection sensor on belt 161 comparator 162 reference voltage signal source 121 yellow photosensitive drum 122 yellow primary charger 123 Yellow developing device 211 LUT (lookup table) 214 CPU 215 RAM 216 PWM (pulse width modulation) device 217 Laser driver 218 ROM 701 Image density detection sensor on drum 702 Light emitting diode 703 Photodiode 704 Comparator 705 Reference voltage signal source

Continued on the front page F term (reference) 2H027 DA09 DA10 DA45 DB01 DE02 DE07 DE10 EA01 EA02 EA06 EB03 EB04 EC03 EC04 EC06 EC07 ED01 ED10 ED24 EE02 EE07 EE08 FA02 FA28 2H077 AD06 AD36 DA04 DA05 DA22 DB31 DA47 DB49 DB63 DA63 GA13

Claims (28)

[Claims] 1. A first detecting means for forming a first reference image on a photoreceptor and detecting the density of the first reference image formed on the photoreceptor, and the first detecting means A first control unit that controls the image forming apparatus based on the detection result detected by the control unit, and a second reference image that is formed on the photoconductor, and the second reference image that is formed on the photoconductor is Second detecting means for transferring the density of the second reference image transferred on the transfer body and transferred on the transfer body, and an image forming apparatus based on a detection result detected by the second detecting means And a second control unit for controlling the control of the second control unit based on a control result of the first control unit. 2. A first detecting means for forming a first reference image on a photoreceptor and detecting the density of the first reference image formed on the photoreceptor, and the first detecting means A first control unit that controls the image forming apparatus based on the detection result detected by the control unit, and a second reference image that is formed on the photoconductor, and the second reference image that is formed on the photoconductor is After transferring on the transfer body,
Second detecting means for detecting the density of the second reference image transferred onto the transfer member, and correction of a gradation correcting means of the image forming apparatus based on a detection result detected by the second detecting means An image forming apparatus comprising: a second control unit configured to control a value; and adjusting control of the second control unit based on a control result of the first control unit. 3. The image forming apparatus according to claim 1, wherein a target value of the control of the second control unit is adjusted based on a control result of the first control unit. 4. The control apparatus according to claim 1, wherein a target value of control of said second control means is adjusted in accordance with an operation state of said image forming apparatus based on a control result of said first control means. 3. The image forming apparatus according to 2. 5. The image forming apparatus according to claim 1, wherein control of said second control means is performed during an interval of control by said first control means. 6. The method according to claim 1, wherein the first reference image is detected.
Detecting means for irradiating the reference image on the photoreceptor with detection light and detecting reflected light or transmitted light thereof to detect the density of the reference image or the amount of adhered image forming agent. The image forming apparatus according to claim 1, wherein: 7. The second detection of the second reference image
Detecting means for irradiating the reference image on the transfer body with detection light and detecting its reflected light or transmitted light, thereby detecting the density of the reference image or the amount of adhesion of the image forming agent. The image forming apparatus according to claim 1, wherein: 8. The image forming apparatus according to claim 1, wherein the transfer body is an image carrier such as an intermediate transfer body, and the second reference image transferred onto the image carrier is detected by the second detection unit. The image forming apparatus according to claim 1. 9. The transfer member is a recording material carrier such as a recording material transport belt, and the second reference image directly transferred onto the recording material carrier is detected by the second detection means. The image forming apparatus according to claim 1, wherein: 10. The method according to claim 1, wherein the first reference image is a single color or
10. The image forming apparatus according to claim 1, wherein the image forming apparatus has a constant density pattern including each color component of a color image. 11. The method according to claim 1, wherein the second reference image is a single color or
11. The image forming apparatus according to claim 1, wherein the image forming apparatus has a constant density pattern including each color component of a color image. 12. The image forming apparatus according to claim 1, wherein the control by the first control unit is an image density control for adjusting a density of a developer. 13. The image forming apparatus according to claim 1, wherein the control by the second control unit is image density control for adjusting a density of a developer. 14. The image forming apparatus according to claim 1, wherein the control by the second control unit is a control for adjusting an exposure amount or a latent image contrast. 15. The control according to claim 2, wherein the control by the second control means is image density and gradation control for correcting and controlling a gradation correction LUT (look-up table) for correcting input image data. 13. The image forming apparatus according to any one of 1 to 12. 16. A method according to claim 16, wherein the control by the second control means adjusts a replenishment amount of the developer such that a parameter calculated from the detected detection signal of the second reference image becomes a target value. By controlling the density of the image, the image density or the gradation characteristic is controlled.
13. The image forming apparatus according to claim 1, wherein the target value is adjusted based on a control result of the control unit. 17. The image forming apparatus forms an electrostatic latent image corresponding to an image pattern on the photoconductor, develops the electrostatic latent image, and transfers the developed image onto a recording material. The image forming apparatus according to claim 1, wherein: 18. The image forming apparatus forms an electrostatic latent image corresponding to an image pattern on the photoconductor, develops the electrostatic latent image, and transfers the developed image to an intermediate transfer member. 17. The image forming apparatus according to claim 1, wherein the image is transferred onto a recording material.
The image forming apparatus according to any one of the above. 19. The image forming apparatus according to claim 1, wherein the image forming apparatus forms a color image by sequentially forming images of a plurality of colors. 20. The image forming apparatus has a plurality of photoconductors, and forms a color image by transferring a plurality of colors of visible images formed on the plurality of photoconductors onto a recording material. An image forming apparatus according to any one of claims 1 to 18, wherein: 21. An electrostatic latent image corresponding to a plurality of color image patterns is formed on a single photoconductor sequentially or on a plurality of photoconductors, and after developing the electrostatic latent image, In a color image forming apparatus for sequentially transferring images onto a recording material or an intermediate transfer member, a first reference density pattern of each color is formed on the photosensitive member, and the first reference density pattern is irradiated with detection light. First detecting means for detecting the density of the first reference density pattern by detecting the reflected light; and detecting the density of the first reference density pattern detected by the first detecting means as a target value. A first control unit for controlling an image density of an output image by controlling a toner density by adjusting a toner supply amount, and forming a second reference density pattern of each color on the photoconductor. And transfer the recording material After transferring the second reference density pattern onto the photoreceptor, by irradiating the second reference density pattern with detection light and detecting its reflected light or transmitted light, the second reference density pattern is copied. Second detecting means for detecting and detecting the density; and adjusting the toner supply amount such that the density of the second reference wettability pattern detected by the second detecting means becomes a target value. And a second control means for controlling the image density of the output image by controlling the target value. The target value of the density of the second reference density pattern is adjusted based on the control result of the first control means. An image forming apparatus, wherein the control of the second control means is executed during the control interval of the first control means. 22. Forming an electrostatic latent image corresponding to an image pattern of a plurality of colors sequentially on a single photoconductor or on a plurality of photoconductors, developing the electrostatic latent image, and then recording In a color image forming apparatus for sequentially transferring images on a material or an intermediate transfer member, a first reference density pattern of each color is formed on the photosensitive member, and the first reference density pattern is irradiated with detection light and reflected. First detecting means for detecting the density of the first reference density pattern by detecting light; and the density of the first reference density pattern detected by the first detecting means becomes a target value. A first control unit for controlling the image density of the output image by controlling the toner density by adjusting the toner supply amount, and forming a second reference density pattern of each color on the photoconductor, On the recording material conveyor or intermediate transfer member After transferring the second reference density pattern, the second reference density pattern is irradiated with detection light to detect reflected light or transmitted light, thereby detecting the density of the second reference density pattern. A second detecting means, and correcting the tone density correcting means so that the density of the second reference density pattern detected by the second detecting means becomes a target value, thereby reducing the image density of the output image. Second to control
Control means for adjusting the target value of the density of the second reference density pattern based on the control result of the first control means, and controlling the target value during the control interval of the first control means. An image forming apparatus for executing control of a second control unit. 23. forming a first reference image on a photoreceptor,
A first detection step of detecting the density of the first reference image formed on the photoconductor, and a first control of controlling the image forming apparatus based on a detection result detected in the first detection step Forming a second reference image on the photoreceptor, transferring the second reference image formed on the photoreceptor onto a transfer member, and transferring the second reference image on the transfer member. A second detection step of detecting the density of the reference image, and a second control step of controlling the image forming apparatus based on a detection result detected in the second detection step, wherein the first control An image forming method, wherein the control in the second control step is adjusted based on a control result in the step. 24. forming a first reference image on a photoreceptor,
A first detection step of detecting the density of the first reference image formed on the photoconductor, and a first control of controlling the image forming apparatus based on a detection result detected in the first detection step Forming a second reference image on the photoreceptor and transferring the second reference image formed on the photoreceptor onto a transfer member;
A second detection step of detecting the density of the second reference image transferred onto the transfer body, and a correction of a gradation correction step of the image forming apparatus based on a detection result detected by the second detection step A second control step of controlling a value, wherein the control in the second control step is adjusted based on a control result in the first control step. 25. An electrostatic latent image corresponding to a plurality of color image patterns is formed on a single photoconductor sequentially or on a plurality of photoconductors, and after developing the electrostatic latent image, In an image forming method of a color image forming apparatus for sequentially transferring images onto a recording material or an intermediate transfer member, a first reference density pattern of each color is formed on the photosensitive member, and a detection light is applied to the first reference density pattern. A first detection step of detecting the density of the first reference density pattern by irradiating the first reference density pattern, and detecting the density of the first reference density pattern detected in the first detection step. A first control step of controlling the image density of the output image by controlling the toner density by adjusting the toner supply amount so that the density becomes a target value; and a second reference of each color on the photoconductor. Forming a density pattern, After transferring the second reference density pattern onto a recording material transporting body or an intermediate transfer body, the second reference density pattern is irradiated with detection light to detect reflected light or transmitted light, thereby obtaining the second reference density pattern. A second detection step for detecting the density of the second reference density pattern; and a toner supply amount such that the density of the second reference wetness pattern detected in the second detection step becomes a target value. A second control step of controlling the image density of the output image by adjusting the toner density by adjusting the density of the second reference density pattern based on a control result of the first control step. During the control interval of the first control step.
An image forming method, wherein the control of the control step is performed. 26. An electrostatic latent image corresponding to an image pattern of a plurality of colors is formed on a single photoconductor sequentially or on a plurality of photoconductors, and the electrostatic latent image is developed and then recorded. In a color image forming apparatus for sequentially transferring images on a material or an intermediate transfer member, a first reference density pattern of each color is formed on the photosensitive member, and the first reference density pattern is irradiated with detection light and reflected. A first detection step of detecting light to detect the density of the first reference density pattern; and a density of the first reference density pattern detected in the first detection step becomes a target value. A first control step of controlling the image density of the output image by controlling the toner density by adjusting the toner supply amount, and forming a second reference density pattern of each color on the photoconductor, Recording material carrier or intermediate After transferring the second reference density pattern onto the transfer member, the detection light is applied to the second reference density pattern to detect reflected light or transmitted light, thereby detecting the second reference density pattern. A second detection step of detecting a density, and an output image by correcting and controlling the gradation correction step so that the density of the second reference density pattern detected in the second detection step becomes a target value. A second control step of controlling the image density of the first control step, wherein a target value of the density of the second reference density pattern is adjusted based on a control result of the first control step; An image forming method, wherein the control of the second control step is executed during the control interval. 27. An electrostatic latent image corresponding to a plurality of color image patterns is formed on a single photoconductor sequentially or on a plurality of photoconductors, and after the electrostatic latent image is developed, A recording medium recording an image formation control program for controlling by a computer a color image forming apparatus that sequentially transfers the image on a recording material or an intermediate transfer member. Forming a first reference density pattern for each color, irradiating the first reference density pattern with detection light and detecting reflected light thereof, thereby detecting the density of the first reference density pattern; The control of the image density of the output image is performed by controlling the toner density by adjusting the toner supply amount so that the detected density of the first reference density pattern becomes the target value. Forming a second reference density pattern of each color on the photoreceptor, transferring the second reference density pattern on a recording material conveyance body or an intermediate transfer body, and then detecting the second reference density pattern with the second reference density pattern. And detecting the reflected light or transmitted light thereof to detect the density of the second reference density pattern. As a second control, the detected density of the second reference density pattern is set to a target value. The image density of the output image is controlled by controlling the toner density by adjusting the toner supply amount such that the density of the second reference density pattern is controlled based on the control result of the first control. Wherein the target value is adjusted and the second control is executed during the interval of the first control. 28. An electrostatic latent image corresponding to a plurality of color image patterns is formed on a single photoconductor sequentially or on a plurality of photoconductors, and after the electrostatic latent image is developed, recording is performed. A recording medium recording an image control program for controlling by a computer a color image forming apparatus that sequentially transfers the image on a material or an intermediate transfer member. Forming a first reference density pattern, irradiating the first reference density pattern with detection light and detecting reflected light thereof, thereby detecting the density of the first reference density pattern. Controlling the image density of the output image by controlling the toner density by adjusting the toner supply amount so that the detected density of the first reference density pattern becomes a target value; A second reference density pattern of each color is formed thereon, and after transferring the second reference density pattern on a recording material transporting body or an intermediate transfer body, the second reference density pattern is irradiated with detection light. By detecting the reflected light or transmitted light, the density of the second reference density pattern is detected. As a second control, the detected density of the second reference density pattern is set to a target value. Controlling the image density of the output image by correcting and controlling the gradation correction step; adjusting the target value of the density of the second reference density pattern based on the control result of the first control; A recording medium on which an image forming program is recorded, wherein the second control is executed during a control interval of the control.