JPH0651599A - Image quality controller - Google Patents

Abstract

PURPOSE:To obtain an image quality controller generating a high quality image by preventing a line from thickening or thinning by controlling a line width in addition to a density control. CONSTITUTION:This controller is constituted of a density control loop to control density and a line width control loop to control the line width. The density control loop compares the toner image of reference density patches 114 and 116 formed on the photosensitive body 106 with a reference density signal and controls the density of a copied image by two inputted quantities out of exposure, electrostatic charging quantity and developing bias quantity. Then, after desired density is obtained, it is shifted to the line width control loop, the line width of the copied image is controlled by the inputted quantity which is not used for the density control by comparing the toner image of the a reference line width patch 124 with the reference line width signal. At such a time, the density differs from the desired density by changing an input controlling the line width. Then, after renewing the input for the line width control, it is returned to the density control loop and the density is controlled. Therefore, this image quality control device possesses a line width predicting means to predict the line width after returning to the desired density by the density control loop and the input direction of the line width control is decided according to a predicted value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality control device capable of controlling image density and line width in an electrophotographic process.

[0002]

2. Description of the Related Art With the rapid progress of OA, there has been a strong demand for a copying machine, a printer and a facsimile machine which can obtain high quality images. Under these demands, it has been possible to measure the density of a copied image and control the image density (for example, Japanese Patent Laid-Open Nos. 55-15185 and 4-85602).

An example of a conventional image quality control device will be described below with reference to the drawings. FIG. 6 is an overall view showing an example of a conventional image quality control device.

In FIG. 6, 100 is a charged corotron,
102 is an exposure subsystem, 104 is a development subsystem, 106 is a photoconductor, 108 is toner, 110 is a document,
112 is a density detector, 114 is a high density reference density patch, 116 is a low density reference density patch, 118 is a toner image for the high density reference density patch 114, 120 is a toner image for the low density reference density patch 116, 122
Is a document table, 200 is a density inspection unit, 1000 is an image quality control unit, and 1002 is a density correction unit.

FIG. 7 is a detailed explanatory diagram of the density inspection unit 200 and the density correction unit 1002 in FIG.

In FIG. 7, 304 is a density qualitative value output means, 306 is a density characteristic curve qualitative value creating means, 314 is a density learning end checking means, 1010 is an input means, 1012 is an input vector storage means, 1014 is an input change vector. Creating means 1016 is an input vector updating means and 1018 is a change input qualitative value creating means.

First, the operation of the electrophotographic process thus configured will be described. The photoconductor 106 receives the inflow current Id by the charging corotron 100 and is charged to the initial surface potential V0. Next, in the exposure subsystem 102, an image of the original 110 is formed on the photoconductor 106 via the illumination and imaging optical system.

At this time, the effective light energy EIM corresponding to the image density DIM is applied to the image portion, and the effective light energy EBG corresponding to the density DBG is applied to each photoconductor 106 in the background portion (background portion). Evenly V before exposure
The surface potential of the photoconductor 106, which was 0, is attenuated by receiving the effective light energy corresponding to the document density, and when reaching the developing subsystem 104, it is VIM in the image portion and VBG in the background portion. Let VDDP be the surface potential of the photoconductor when the exposure subsystem 102 receives no light. Toner concentration TC of toner 108 and tribo TB
And various setting parameters of the developing device (sleeve rotation speed,
The amount of toner corresponding to the surface potential of the photoconductor 106 is developed from the distance between the sleeve and the photoconductor 106, the magnetization pattern, the bias voltage VBIAS, etc.) and adheres to the surface of the photoconductor 106. At the same time, a toner image 118 is formed on the high density reference density patch 114, and a toner image 120 is formed on the low density reference density patch 116.

The above is the basic operation up to the development in the electrophotographic process. In the electrophotographic process, the charging subprocess, the exposure subprocess, and the development subprocess are performed in this way.
A toner image is formed on the photoconductor 106 through one sub-process. When the image density of the original 110 is the input image density DIM and the corresponding density DS of the toner image on the photoconductor 106 is the output image density, the relationship between the two can be expressed by the following equation when the input image is a solid image. .

[0010]

[Equation 1]

[0011]

[Equation 2]

[0012]

[Equation 3]

Here, S is the sensitivity of the photoconductor 106,
γ S is a constant determined by each parameter of the development sub-process 104, the physical properties and deterioration degree of the toner 108, the film thickness and the dielectric constant of the photoconductor 106, and the like. In addition, the photoconductor surface potential V DDP, effective light energy E BG, bias voltage V B
IAS is an adjustable parameter, and by adjusting these, the output image density DS with respect to the input image density DIM
It is possible to adjust the value of. Photoconductor surface potential VDD
Although P cannot be operated directly, it can be operated indirectly by operating the inflow current Id from the charging corotron 100.

The relationship between the input image density DIM and the output image density DS is expressed by the following equations (1) to (3).

[0015]

[Equation 4]

The above equation is obtained, and the measured concentration characteristic curve shown in FIG. 8 is obtained. The purpose of the conventional image quality control is to match the measured density characteristic curve with the desired target density characteristic curve. Therefore, if the functions (Equation 1) to (Equation 3) representing the characteristics of the electrophotographic process can be quantitatively obtained, the input vector satisfying this purpose can be obtained. However, the photoconductor sensitivity S of (Equation 2)
Is a parameter that changes depending on the environmental temperature, the degree of deterioration, the amount of static elimination light, the light quality, etc., and γS in (Equation 3) is also each parameter of the development subprocess, the physical properties and deterioration degree of the toner, the film thickness and the dielectric constant of the photoconductor, etc. Since it is a constant determined by, it is very difficult to quantitatively and precisely grasp them.
Therefore, for example, in Japanese Patent Application No. 202202/1990, the image surface control unit 1000 controls the photosensitive member surface potential VDD.
The input vector X composed of P, the effective light energy EBG, and the bias voltage VBIAS is changed based on the qualitative model, and the measured concentration characteristic curve is moved in parallel and rotationally to match the target concentration curve. The qualitative model is a qualitative expression showing how the sign of the output value changes depending on the sign of the input vector, that is, whether it is positive, negative, or zero.

The operation of the conventional image quality control unit 1000 will be described in detail below. Now, the photoconductor surface potential VDD, which is an input to the electrophotographic process, is input by the input means 1010.
Input vector composed of P, effective light energy EBG, and bias voltage VBIAS,

[0018]

[Equation 5]

Based on the above, the k-th trial is performed, and an output vector composed of the density Ds_h of the high density portion and the density Ds_l of the low density portion detected by the density detector 112,

[0020]

[Equation 6]

It is assumed that the following is realized. At this time, the input vector storage means 1012 stores the input means 1010 in the kth trial.
The input vector X (k) input to the electrophotographic process is stored as the reference input vector Xold. Before the first trial (initial state), the reference input vector Xold is given and stored as the initial input vector Xini. The density qualitative value output means 304 outputs the output vector Y,
The reference high density signal Ds_, which is the desired value of these two densities.
The deviation vector e and the reference output vector Yd composed of the reference low density signal Ds_ld are compared to obtain the deviation vector e,

[0022]

[Equation 7]

The qualitative values [e1] and [e2] of are output. Here, [] represents a value focusing only on the sign of the variable,
It outputs +1 for positive, 0 for 0, and -1 for negative.

Next, the density characteristic curve qualitative value creating means 306
Accordingly, from the qualitative values [e1] and [e2] output from the density qualitative value output means 304, the parallel movement of the actually measured density characteristic curve, that is, the qualitative value [Ds] of the output image density and the qualitative value [α of the rotational movement. ] Is generated. This can be set as shown in (Table 1) from the characteristics of the density characteristic curve.

[0025]

[Table 1]

Then, the change input qualitative value creating means 1018
Thus, the input change vector qualitative value is determined from the output of the density characteristic curve qualitative value creating means 306. First, the parallel movement will be described. Since the parallel movement can be described by (Equation 4), the qualitative expression is

[0027]

[Equation 8]

It can be represented by That is, (Equation 8)
Is the output image density Ds if the photoconductor surface potential V DDP increases.
The effective light energy EBG and bias voltage VBIAS
Means that the output image density Ds decreases as the value increases. Therefore, when it is desired to increase the output image density Ds, that is,

[0029]

[Equation 9]

In the case of, the qualitative value of each element of the input vector X is

[0031]

[Equation 10]

[0032]

[Equation 11]

[0033]

[Equation 12]

Then, the surface potential VDDP of the photoconductor is increased,
It can be seen that the effective light energy EBG and the bias voltage VBIAS variables should be reduced. Also,

[0035]

[Equation 13]

In the case of, all the qualitative values of the respective elements of the input vector X are 0.

[0037]

[Equation 14]

In the case of, of course, (Equation 10) to (Equation 12)
The opposite output, that is, the sign is opposite. Next, the rotational movement will be described. If a qualitative expression is derived from an expression obtained by partially differentiating (Equation 4) with the input image density DIM,

[0039]

[Equation 15]

Is obtained. Therefore, the qualitative value of each element of the input vector X is determined by the signs of the qualitative values [Ds] and [α] output from the density characteristic curve qualitative value creating means 306, and (Equation 8) and (Equation 15). .

An example of the operation up to this point is as follows.
When the density Ds_h in the high density portion is higher than the reference high density signal Ds_hd and the density Ds_l in the low density portion is lower than the reference low density signal Ds_ld, (Equation 7)

[0042]

[Equation 16]

[0043]

[Equation 17]

It is Therefore, from (Table 1),

[0045]

[Equation 18]

It becomes Then, according to (Equation 15),

[0047]

[Formula 19]

[0048]

[Equation 20]

It becomes That is, it can be seen that the photoreceptor surface potential VDDP and the effective light energy EBG should be reduced.

Next, the input change vector creating means 1014
Outputs a value obtained by multiplying the output of the change input qualitative value creating means 1018 with δVDDP, δEBG, and δVBIAS being positive small changes. That is, the first element is + δV DDP, 0, −δ
Select any one of VDDP and set the second element to + δ
An input change vector ΔX obtained by selecting any one of EBG, 0, −δEBG and selecting one of the third elements from + δVBIAS, 0, −δVBIAS is created.

Input vector updating means 1016
The input change vector ΔX is added to the reference input vector Xold to create the k + 1-th input vector X (k + 1), and this input is added to the electrophotographic process by the density input means 300, and the same operation is repeated. By repeating learning in this way, a desired image can be obtained.

A density learning end inspection means 314 is installed between the density qualitative value output means 304 and the density characteristic curve qualitative value creation means 306, and the density qualitative value output means 30 is provided.
When all the qualitative values which are the outputs of 4 are 0, it is determined that the desired image is obtained, and the learning operation is ended.

[0053]

In the conventional image quality control apparatus, since the density of the copied image was controlled, the density contrast of the solid portion was good, but when copying an image such as a thin line, the line becomes thin or thick. Occasionally, there was a phenomenon. Further, even when trying to control the line width, the conventional control method cannot control the line width independently because the qualitative expressions of the density and the line width are the same. Therefore, there are problems that thin lines disappear and characters are crushed.

[0054]

In order to solve the above-mentioned problems, an image quality control apparatus of the present invention comprises a charging means for charging a photoconductor to a charging voltage and an original on a platen with a predetermined exposure amount. Exposing means for forming a latent image on the photoconductor, developing means for forming a visible image of the latent image with a developer set to a predetermined developing bias voltage, and transferring the visible image to a transfer sheet. In an electrophotographic process including a transfer unit, at least one reference density patch having a uniform density placed on the original table and at least one reference line width patch including a high density portion and a low density portion A reference patch group having, a density detecting unit for detecting the output density of the visible image formed on the photoconductor by the charging, exposing, and developing the reference density patch; and the charging of the reference line width patch, Exposure, development A line width detecting means for detecting a line width from a visible image formed on the photosensitive member by a step, a reference density signal, a reference line width signal, and a comparison between the reference density signal and the output of the density detecting means. Then, there is provided density qualitative value output means for outputting a qualitative value that the output of the density detecting means is larger, equal to or smaller than the reference density signal.

A line width that compares the reference line width signal with the output of the line width detecting means and outputs a qualitative value that the output of the line width detecting means is larger, equal to or smaller than the reference line width signal. The qualitative value output means, the charging means, the exposure means, and the developing means, respectively, are increased or decreased to increase or decrease the output of the density detecting means. There is a qualitative model part that remembers various relationships.

If the output of the density qualitative value output means is not the output that the output of the density detection means is equal to the reference density signal, any one of the charging means, the exposing means and the developing means. While the input value α to A is fixed, the respective input values β and γ to the remaining two means B and C are used to determine the qualitative relationship of the qualitative model unit and the concentration qualitative value output means. The density input value updating operation of increasing, decreasing, or not changing according to the output is performed.

The output of the density qualitative value output means is
Density control means for repeatedly executing the density input value updating operation until the output of the density detection means and the reference density signal are equal, and the output of the density detection means by the density control means and the reference density signal Then, the change in the output of the concentration detecting means caused by increasing or decreasing the input value α to the means A is performed again by the concentration controlling means, and the output of the concentration qualitative value outputting means is changed to A line width predicting means for predicting an output of the line width qualitative value output means after returning to an output that the output of the density detecting means is equal to the reference density signal, and the density controlling means of the density detecting means. The output and the reference density signal are made equal.

Thereafter, if the output of the line width qualitative value output means is not the output that the output of the line width detection means and the reference line width signal are equal, the means B and the means C
The input value β and the input value γ are fixed, and the input value α to the means A is set in accordance with the output of the line width prediction means and the output of the line width qualitative value output means. The line width input value updating operation for increasing or decreasing is performed, and after the line width input value updating operation is executed, the density control means is executed again, and the output of the line width qualitative value output means is the line width detecting means. And a line width control means for repeatedly executing a series of operations until the output that the output of 1 is equal to the reference line width signal is output.

[0059]

The present invention provides an image quality control device which can control the line width and the like of a copied image and can generate a high quality image by controlling the line width in addition to the conventional density control. Will be possible.

[0060]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image quality control apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall view showing the structure of an image quality control device according to the first embodiment of the present invention.

In FIG. 1, 100 is a charged corotron,
102 is an exposure subsystem, 104 is a development subsystem, 106 is a photoconductor, 108 is toner, 110 is a document,
112 is a density detector, 114 is a high density reference density patch, 116 is a low density reference density patch, 118 is a toner image for the high density reference density patch 114, 120 is a toner image for the low density reference density patch 116, 122
Is a document table, 124 is a reference line width patch, 126 is a toner image for the reference line width patch 124, 128 is a line width detector,
130 is an image quality control unit, 150 is a control command unit, 200 is a density inspection unit, 202 is a density correction unit, 204 is a line width inspection unit,
A line width correction unit 206 is provided.

FIG. 2 is a detailed explanatory diagram of the density inspection unit 200 and the density correction unit 202 in FIG.

In FIG. 2, 250 is a qualitative model part, 2
52 is a density control means, 300 is a density input means, 302 is a density input vector storage means, 304 is a density qualitative value output means, 306 is a density characteristic curve qualitative value creating means, 308 is a density change input qualitative value creating means, and 310 is Density input change vector creating means, 312 is density input vector updating means, 3
Reference numeral 14 is a concentration learning end inspection means.

FIG. 3 is a detailed explanatory diagram of the line width inspection unit 204 and the line width correction unit 206 in FIG.

In FIG. 3, reference numeral 260 denotes a line width predicting means, 2
62 is a line width control means, 350 is a line width input means, 352 is a line width input storage means, 354 is a line width qualitative value output means, 35
6 is a line width change input qualitative value creating means, 360 is a line width input change value creating means, 362 is a line width input updating means, and 364 is a line width learning end checking means.

The operation of the image quality control device configured as described above will be described below with reference to FIGS. 1, 2 and 3.

First, the operation of the electrophotographic process is the same as in the conventional example. In the conventional example, the reference patch is only the reference density patch, but in the present embodiment, the reference line width patch 124 is added. . Then, similarly to the reference density patch, the toner image 126 of the reference line width patch 124 is formed on the photoconductor 106.

Next, the operation of the image quality control unit 130 will be described below. The image quality control unit 130 includes a control command unit 150 that determines a control plan for density and line width, a density inspection unit 200 and density correction unit 202 for density control, and a line width inspection unit 204 for line width control. It is composed of the line width correction unit 206. Of the photoreceptor surface potential VDDP, the effective light energy EBG, and the bias voltage VBIAS, which are the inputs to the electrophotographic process, the inputs for controlling the density are the photoreceptor surface potential VDDP and the effective light energy EBG, and the line width is controlled. It is assumed that the bias voltage VBIAS is applied to the input.

In this case, first, the control command unit 15
0 will be described. The control command unit first executes the density control, then executes the line width control after the density control is completed, and then executes the density control again. Repeatedly control until it becomes. That is, first, the line width input unit 350, which is a part of the line width correction unit 206, does not change the bias voltage VBIAS, which is an input for line width control, and the density inspection unit 200 and the density correction unit 202 for density control do not change. The concentration control loop consisting of and is executed. Here, this concentration control loop will be described. In response to a command from the control command section 150, the density input means 300 inputs the density control to the photosensitive member surface potential VDD.
P, an input vector composed of effective light energy EBG,

[0071]

[Equation 21]

Based on the above, the k-th trial is performed, and the output vector composed of the density Ds_h of the high density portion and the density Ds_l of the low density portion detected by the density detector 112,

[0073]

[Equation 22]

It is assumed that the following is realized. At this time, the density input vector storage means 302 stores the density input means 3 in the kth trial.
Input vector Xd of 00 input to the electrophotographic process
Store (k) as the reference density input vector Xd-old. In the first trial, the initial density input vector Xd-ini is input to the electrophotographic process from the density input means 300, and the initial line width input Xl-ini is input to the electrophotographic process from the line width input means 350.
Before the first trial (initial state), the reference concentration input vector Xd-old is set to the initial concentration input vector Xd-in.
Give i and remember. Here, the operations of the density qualitative value output means 304, the density characteristic curve qualitative value creation means 306, and the density learning end inspection means 314 are the same as in the conventional example. Further, the density change input qualitative value creating means 308 is basically the same as the change input qualitative value creating means 1018 in the conventional example, but outputs only those necessary for controlling the density.
That is, here, only those relating to the photoconductor surface potential VDDP and the effective light energy EBG are output.

Thereafter, the density input change vector creating means 31
0 is basically the input change vector creating means 10 of the conventional example.
Although it is the same as 14, the output of the density change input qualitative value creating means 308 is multiplied and output here by using δVDDP and δEBG as positive minute changes. That is, the first element +
A density input change vector ΔXd obtained by selecting any one of δVDDP, 0, −δVDDP and selecting one of the second elements from + δEBG, 0, −δEBG is created.

Then, the density input vector updating means 312
Is the reference density input vector Xd-old plus the density input change vector ΔXd, and the k + 1th input vector Xd
(K + 1) is created, and this input is added to the electrophotographic process by the density input means 300, and the same operation is repeated. In this way, the density learning completion detecting unit 314 determines that the image having the desired density is obtained, and the learning is repeatedly performed until the learning operation is completed, whereby the image having the desired density can be obtained.

Next, when the control command section 150 receives a signal indicating that the density learning end detecting means 314 has obtained an image of a desired density, the line width inspection section 20 for line width control.
4. A line width control loop including the line width correction unit 206 is executed. Here, the line width control loop will be described.
It is assumed that the line width detector 128 detects the line width Lw when the density learning end inspection unit 314 determines that the image having the desired density is obtained and ends the learning operation. At this time,
The line width qualitative value output means 354 compares this line width with the reference line width signal Lwd which is the desired value of this line width, and outputs the qualitative value [e3] of the deviation value e3.

The theoretical expressions of the surface potential VDDP of the photoconductor, the effective light energy EBG, the bias voltage VBIAS, and the line width Lw, which are the inputs to the electrophotographic process, are as follows:

[0079]

[Equation 23]

It can be derived as follows. Here, K is a constant determined by the optical system, and Lo is a constant determined by the line width of the input image. Therefore, the qualitative relationship between the line width Lw and the input is

[0081]

[Equation 24]

The following relationship is obtained. However, since this qualitative formula is the same as that of (Equation 8), the density and line width cannot be controlled independently as they are. In addition, the input for controlling the density is the photoconductor surface potential VDDP and the effective light energy EBG.
Even if the input for controlling the line width is separated from the bias voltage VBIAS, the concentration and the line width interfere with each other. Therefore, after controlling the concentration to the desired concentration, the bias voltage VBIAS is changed to control the line width. If so, the density naturally deviates from the desired density.

Therefore, the line width predicting means 260 uses (Equation 4)
From the theoretical formula of (Equation 23) and (Equation 23), after the density is fixed to the desired density by the density correction unit 202 by using the expression in which the density is fixed by the photoconductor surface potential VDDP and the effective light energy EBG,
When the bias voltage VBIAS is changed in order to control the line width, the density deviated from the desired density is again corrected by the density correction unit 20.
2 makes it possible to predict the change in line width after controlling the density to a desired value. When the input for controlling the line width is the bias voltage VBIAS, from the theoretical formulas of (Equation 4) and (Equation 23), an expression in which the density is fixed by the photoreceptor surface potential VDDP and the effective light energy EBG, that is, the line width Lw If a qualitative expression is obtained from the relational expression between the bias voltage VBIAS and

[0084]

[Equation 25]

It becomes Therefore, the line width change input qualitative value creating unit 356 determines the bias voltage from the output of the line width qualitative value output unit 354 according to the qualitative value of the line width change predicted by the line width predicting unit 260, that is, (Equation 25). Create a qualitative value for VBIAS.

Next, the line width input change value creating means 360
δVBIAS is set as a positive minute change amount, and the output of the line width change input qualitative value creating means 356 is multiplied and output. That is, + δVBI
A line width input change value ΔXl obtained by selecting any one of AS, 0, -δVBIAS is created.

Then, the line width input value updating means 362 adds the line width input change value ΔXl to the reference line width input value Xl-old to create the jth input value Xl (j), and inputs the line width. By means of means 350, the photoreceptor surface potential V which is the input of the density control
The input vector composed of DDP and effective light energy EBG does not change and is applied to the electrophotographic process with the bias voltage VBIAS as Xl (j). At this time, the line width input storage means 352 stores the input Xl (j) input to the electrophotographic process by the line width input means 350 in the j-th trial as the reference line width input Xl-old. Before the first trial (initial state), the reference line width input Xl-old is given an initial line width input Xl-ini and stored.

After that, the control command section 150 shifts to a density control loop consisting of the density inspection section 200 and the density correction section 202, and repeatedly executes until the desired density is reached, and the density learning end detection means 314 causes the image of the desired density to be obtained. When receiving the signal that the line width is obtained, the process again moves to the line width control loop including the line width inspection unit 204 for line width control and the line width correction unit 206. The above series of operations is repeated until the desired line width is obtained. In this way, by repeating learning, it is possible to obtain an image that realizes a desired density and line width. A line width learning end inspection unit 364 is installed between the line width qualitative value output unit 354 and the line width change input qualitative value creation unit 356, and the qualitative value output from the line width qualitative value output unit 354 is When it is 0, it is determined that the desired image is obtained, and the learning operation is ended.

Here, an example of the operation up to this point will be shown.
Now, it is assumed that an image having a desired density can be obtained by the density control loop as in the conventional example. However, in this case, since the inputs for controlling the density are the photoreceptor surface potential VDDP and the effective light energy EBG, the control is performed without changing the bias voltage VBIAS. At this time, the line width Lw is thicker than the reference line width signal Lwd, that is,

[0090]

[Equation 26]

If it is, it is necessary to make the line width Lw narrower. Therefore, based on the line width prediction means, from (Equation 25),

[0092]

[Equation 27]

It becomes That is, it is understood that the bias voltage VBIAS should be increased. Therefore, if the bias voltage VBIAS is increased in accordance with this, the output density becomes thin according to the relational expression (Equation 8). So, again, return to the concentration control loop,
The image of the desired density is restored by the photoconductor surface potential VDDP and the effective light energy EBG.

By repeatedly learning a series of operations in this manner, the line width can be controlled in addition to the conventional density control, and a desired image can be obtained.

When the input for controlling the density is the effective light energy EBG and the bias voltage VBIAS and the input for controlling the line width is the photoconductor surface potential VDDP, or the input for controlling the density is the photoconductor surface potential VDDP. And the bias voltage VBIAS, and the input that controls the line width is the effective optical energy E.
In the case of BG, when the line width is predicted by the line width predicting unit 260, it is not uniquely determined, and it is necessary to divide the case depending on the input value at that time. Therefore, the structure of the line width prediction means 260 becomes complicated. Therefore, as in the first embodiment, the input for controlling the density is the photoreceptor surface potential VDDP and the effective light energy EBG, and the input for controlling the line width is the bias voltage VBIAS.
This has the advantage of simplifying the configuration.

On the other hand, in the first embodiment, when the input for controlling the line width in the line width control loop is updated, the density deviates from the desired value, and the learning operation is required again in the density control loop. Will be significantly increased.

Therefore, as a second embodiment of the present invention, the change in density when the input for controlling the line width is updated in the line width control loop is predicted, and the density for canceling this change in density is controlled. Provided is an image quality control device that suppresses an increase in the number of times of learning by predicting and changing the amount of change in input.

An image quality control apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is an overall view showing the configuration of the image quality control device in the second embodiment of the present invention.

In FIG. 4, 100 is a charged corotron,
102 is an exposure subsystem, 104 is a development subsystem, 106 is a photoconductor, 108 is toner, 110 is a document,
112 is a density detector, 114 is a high density reference density patch, 116 is a low density reference density patch, 118 is a toner image for the high density reference density patch 114, 120 is a toner image for the low density reference density patch 116, 122
Is a document table, 124 is a reference line width patch, 126 is a toner image for the reference line width patch 124, 128 is a line width detector,
Reference numeral 150 is a control command unit, 200 is a density inspection unit, 204 is a line width inspection unit, 400 is an image quality control unit, 401 is a density correction unit,
Reference numeral 402 is a line width correction unit, and 404 is a density restoration prediction means.

FIG. 5 is a detailed explanatory diagram of the density correction section 401, line width correction section 402 and density restoration prediction means 404 in FIG.

In FIG. 5, reference numeral 200 denotes a density inspection unit, 20
4 is a line width inspection unit, 250 is a qualitative model unit, 260 is a line width prediction unit, 262 is a line width control unit, 300 is a density input unit, 302 is a density input vector storage unit, 310 is a density input change vector creation unit, Reference numeral 312 is a density input vector updating means, 356 is a line width change input qualitative value generating means, 40
Reference numeral 1 is a density correction unit, 402 is a line width correction unit, 404 is a density restoration prediction unit, and 406 is a density control unit.

The operation of the image quality control device configured as described above will be described below with reference to FIGS. 4 and 5.

First, the operation of the electrophotographic process is the same as in the first embodiment. Therefore, the image quality control unit 400
The operation will be described below.

The image quality control section 400 includes a control command section 150 for determining a control plan for density and line width, a density inspection section 200 for density control, a density correction section 401, and a line width inspection for line width control. It is composed of a unit 204, a line width correction unit 402, and a density restoration prediction unit 404. Now, of the photoconductor surface potential VDDP, the effective light energy EBG, and the bias voltage VBIAS, which are inputs to the electrophotographic process, the input for controlling the density is the photoconductor surface potential VDDP and the effective light energy E.
BG, and the bias voltage VBIAS is used as the input for controlling the line width.

This case will be described. Control Command 1
50, the density inspection unit 200 and the density correction unit 401 in the density control loop, and the line width inspection unit 2 in the line width control loop
04 and the line width correction unit 402 have the same basic operations as in the first embodiment, except that the control command unit 150 receives a signal indicating that the density learning end detection unit 314 has obtained a desired density image, When a line width control loop including a line width inspection unit 204 and a line width correction unit 402 for line width control is executed,
In accordance with the qualitative value of the line width change predicted by the line width predicting means 260, the line width change input qualitative value creating means 356 creates a qualitative value of the bias voltage VBIAS, and the line width control means 26.
In addition to updating and outputting the bias voltage VBIAS from 2, the qualitative value of the change in line width predicted by the line width predicting means 260 is also input to the density restoration predicting means 404. The density restoration prediction means 404 predicts a change in density due to a change in the bias voltage VBIAS updated by the line width control means 262, and an input amount for correcting this density change, that is, here, the photosensitive member surface potential VDDP and the effective value. The change amount of the light energy EBG is calculated and output to the density input vector updating means 312 in the density control means 406 and updated. As a result, it is possible to suppress an increase in the number of times of learning that occurs when the line width control is added to the density control, and the control time is shortened.

[0107]

As described above, according to the present invention, in the charging means for charging the photoconductor, the exposing means, the developing means, and the electrophotographic process, at least a uniform density is placed on the platen. A reference patch group having one reference density patch and at least one reference line width patch composed of a high density portion and a low density portion, and the reference density patch are formed on the photoconductor by the charging, exposing and developing means. Density detecting means for detecting the output density of the visible image, and line width detecting means for detecting the line width from the visible image formed on the photoconductor by the charging, exposing and developing means for the reference line width patch. ,
The reference density signal, the reference line width signal, the reference density signal and the output of the density detecting means are compared.

A density qualitative value output means for outputting a qualitative value that the output of the density detecting means is larger than, equal to, or smaller than the reference density signal.

Further, the reference line width signal is compared with the output of the line width detecting means, and a qualitative value that the output of the line width detecting means is larger than, equal to or smaller than the reference line width signal is outputted. By increasing or decreasing the respective inputs to the line width qualitative value output means, the charging means, the exposing means, and the developing means, it is said that the output of the density detecting means increases, does not change, or decreases. It is a qualitative model part that stores qualitative relationships.

If the output of the density qualitative value output means is not the output that the output of the density detection means is equal to the reference density signal, any one of the charging means, the exposing means and the developing means. While the input value α to one means A is fixed, the respective input values β and input values γ to the other two means B and means C are converted into a qualitative relationship of the qualitative model unit and the concentration qualitative value output. A density input value updating operation of increasing, decreasing, or not changing according to the output of the means is performed, and the output of the density qualitative value output means becomes an output that the output of the density detecting means and the reference density signal are equal. Until then, the density control means repeatedly executes the density input value updating operation, and the density control means equalizes the output of the density detection means with the reference density signal.

After that, the change in the output of the concentration detecting means caused by increasing or decreasing the input value α to the means A is again returned to the output of the concentration qualitative value output means by the concentration controlling means. Line width predicting means for predicting the output of the line width qualitative value output means after returning to the output that the output of the density detecting means is equal to the reference density signal, and the output of the density detecting means by the density controlling means. If the output of the line width qualitative value output means is not the output that the output of the line width detection means is equal to the reference line width signal after equalizing the reference density signal with the reference density signal, the means B and the means The input value β and the input value γ to C are fixed, and the input value α to the means A is fixed.
In accordance with the output of the line width predicting means and the output of the line width qualifying value output means, a line width input value updating operation for increasing or decreasing is performed.

After the line width input value updating operation is executed, the density control means is executed again so that the output of the line width qualitative value output means is the same as the output of the line width detection means and the reference line width signal. By providing a line width control unit that repeatedly executes a series of operations until the outputs are equal, the line width of the output image can be controlled in addition to the density control of the conventional output image, and a high-quality output image can be obtained. Can be realized.

[Brief description of drawings]

FIG. 1 is an overall view showing a configuration of an image quality control device according to a first embodiment of the present invention.

FIG. 2 is a detailed explanatory diagram of a density inspection unit and a density correction unit in FIG.

FIG. 3 is a detailed explanatory diagram of a line width inspection unit and a line width correction unit in FIG.

FIG. 4 is an overall diagram showing a configuration of an image quality control device according to a second embodiment of the present invention.

5 is a detailed explanatory diagram of a density correction unit, a line width correction unit, and a density repair prediction unit in FIG.

FIG. 6 is an overall view showing an example of a conventional image quality control device.

7 is a detailed explanatory diagram of a conventional image quality control unit in FIG.

FIG. 8 is a conventional image density characteristic diagram.

[Explanation of symbols]

100 Charging Corotron 102 Exposure Subsystem 104 Development Subsystem 106 Photoreceptor 108 Toner 110 Originals 112 Density Detector 114 High Density Reference Density Patch 116 Low Density Reference Density Patch 118 Toner Image for High Density Reference Density Patch 114 120 Low Density Image of the reference density patch 116 of 122 122 original plate 124 reference line width patch 126 toner image of the reference line width patch 128 line width detector 130 image quality control unit 150 control command unit 200 density inspection unit 202 density correction unit 204 line width inspection Part 206 Line width correction part 250 Qualitative model part 252 Density control means 260 Line width prediction means 262 Line width control means 300 Density input means 302 Density input vector storage means 304 Density qualitative value output means 306 Density characteristic curve qualitative value creation Step 308 Density change input qualitative value creating means 310 Density input change vector creating means 312 Density input vector updating means 314 Density learning end checking means 350 Line width input means 352 Line width input storage means 354 Line width qualitative value output means 356 Line width change Input qualitative value creation means 360 Line width input change value creation means 362 Line width input update means 364 Line width learning end inspection means 400 Image quality control section 401 Density correction section 402 Line width correction section 404 Density restoration prediction means 406 Density control means 1000 Image quality Control unit 1002 Density correction unit 1010 Input means 1012 Input vector storage means 1014 Input change vector creation means 1016 Input vector update means 1018 Learning end inspection means

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[Procedure amendment]

[Submission date] August 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

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[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

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[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

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[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

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[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 5

[Correction method] Change

[Correction content]

Claims (12)

[Claims] 1. A charging unit for charging a photosensitive member to a predetermined charging voltage, an exposing unit for projecting an exposure amount to form a latent image on the photosensitive member, and the latent image set to a predetermined developing bias voltage. In the electrophotographic process including a developing means for forming a visible image with the developer and a transferring means for transferring the visible image onto a transfer sheet, the density is at least uniform on the platen. A reference patch group having one reference density patch and at least one reference line width patch including a high density portion and a low density portion is provided. Density detecting means for detecting the output density of the visible image formed on the photoconductor by the charging, exposing and developing means for the reference density patch,
A line width detecting unit for detecting a line width from a visible image formed on the photosensitive member by the charging, exposing, and developing unit for the reference line width patch, a reference density signal, and a reference line width signal are detected. The density of the copied image is controlled by comparing the output of the density detecting means with the reference density signal, and the line width of the copied image is controlled by comparing the output of the line width detecting means with the reference line width signal. An image quality control unit is provided, and the image quality control unit compares the reference density signal with the output of the density detection unit, and the output of the density detection unit is greater than, equal to, or less than the reference density signal. A density qualitative value output means for outputting a qualitative value, comparing the output of the reference line width signal and the line width detection means, the output of the line width detection means is greater than or equal to the reference line width signal, Alternatively, the line width qualitative value output means outputs a qualitative value of being small. By storing the qualitative relationship that the output of the density detecting means increases, does not change, or decreases by increasing or decreasing the respective inputs to the charging means, the exposing means and the developing means. If the output of the qualitative model section and the density qualitative value output means is not the output that the output of the density detection means is equal to the reference density signal, one of the charging means, the exposing means and the developing means. While the input value α to one means A is fixed, the respective input values β and input values γ to the other two means B and means C are used to determine the qualitative relationship of the qualitative model part and the concentration qualitative value. The density input value updating operation of increasing, decreasing, or not changing according to the output of the output means is performed. A density control means for repeatedly executing the density input value updating operation until the output of the density qualitative value output means becomes an output that the output of the density detection means and the reference density signal are equal, and the density control means After equalizing the output of the density detecting means and the reference density signal,
The change in the output of the density detecting means caused by increasing or decreasing the input value α to the means A is again output by the density controlling means by the output of the density qualitative value outputting means. And the reference density signal is equal to each other. After that, the line width predicting means for predicting the output of the line width qualitative value output means and the density control means make the output of the density detecting means equal to the reference density signal, and then the line width qualitative value outputting means The output is
When the output of the line width detecting means and the output of the reference line width signal are not equal, the input value β and the input value γ to the means B and the means C are fixed and the means A is kept. The input value α to the line width predicting means and the line width qualitative value output means are increased or decreased to perform a line width input value updating operation, and the line width input value updating operation is performed. After the execution, the density control means is executed again, and a series of operations are repeated until the output of the line width qualitative value output means becomes an output that the output of the line width detection means and the reference line width signal are equal. An image quality control device comprising: a line width control unit for executing the image quality control. 2. The density control means, when the output of the density qualitative value output means is not such that the output of the density detection means and the reference density signal are equal, the input value to the developing means is fixed and the charging means. The density input value updating operation is performed such that the respective input values to the exposure means and the exposure means are increased, decreased or not changed according to the qualitative relation of the qualitative model portion and the output of the density qualitative value output means. Thereafter, the density input value updating operation is repeatedly executed until the output of the density qualitative value output means becomes an output that the output of the density detection means and the reference density signal are equal, and the line width prediction means The control means equalizes the output of the density detecting means and the reference density signal. Furthermore, the change in the output of the density detecting means caused by increasing or decreasing the input value to the developing means is again output by the density controlling means to the output of the density qualitative value outputting means. And the reference density signal are returned to the same output, the line width qualitative value output means predicts the output, and the line width control means causes the density control means to output the density detection means and the reference density. Make the signal equal to. After that, when the output of the line width qualitative value output means is not the output that the output of the line width detection means and the reference line width signal are equal,
The input values to the charging unit and the exposure unit are fixed, and the input values to the developing unit are increased or decreased according to the outputs of the line width prediction unit and the line width qualitative value output unit. After performing the line width input value updating operation and executing the line width input value updating operation, the density control means is executed again, and the output of the line width qualitative value output means is the same as the output of the line width detecting means. 2. The image quality control apparatus according to claim 1, wherein a series of operations are repeatedly executed until an output indicating that the reference line width signal is equal. 3. An image quality control section, after the density control means equalizes the output of the density detection means and the reference density signal, means A
The change in the output of the concentration detecting means caused by increasing or decreasing the input value α to the is predicted. The amount of change in each of the input value β and the input value γ to the means B and the means C for returning the output of the density detecting means to the output of the density detecting means before increasing or decreasing the input value α to the means A And a line width control means for making the output of the density detection means equal to the reference density signal by the density control means, and then the output of the line width qualitative value output means When the output of the detection means and the reference line width signal are not equal, the input value α to the means A is set to the output of the line width prediction means and the output of the line width qualitative value output means, A line width input value updating operation for increasing or decreasing is performed, and the input value β and the input value γ to the means B and the means C are increased or decreased in accordance with the output of the density restoration prediction means. Input value restoration operation Cormorant. After performing the line width input value updating operation and the density input value restoring operation, the density control means is executed again, and the output of the line width qualitative value output means is the output of the line width detecting means and the reference. 2. The image quality control device according to claim 1, wherein a series of operations are repeatedly executed until the outputs are equal to the line width signal. 4. A line width detecting means charges a reference line width patch,
A resolution detecting unit that detects the resolution from the visible image formed on the photoconductor by the exposing and developing unit, and the image quality control unit
A reference density signal and a reference resolution signal are provided, the output of the density detection means is compared with the reference density signal to control the density of the copied image, and the output of the resolution detection means is compared with the reference resolution signal. For controlling the resolution of the copied image, the line width qualitative value output means of the image quality control section compares the reference resolution signal with the output of the resolution detection means, and outputs the resolution detection means. Is set to a resolution qualitative value output means for outputting a qualitative value that is greater than, equal to, or less than the reference resolution signal. Then, the line width predicting means equalizes the output of the density detecting means and the reference density signal by the density controlling means, and then the input value to any one of the charging means, the exposing means and the developing means. The change in the output of the density detecting means caused by increasing or decreasing α is again made by the density controlling means so that the output of the density qualitative value output means is equal to the output of the density detecting means. Is a resolution prediction means for predicting the output of the resolution qualitative value output means after returning to the output, and the line width control means makes the output of the density detection means equal to the reference density signal by the density control means. After that, if the output of the resolution qualitative value output means is not the output that the output of the resolution detection means and the reference resolution signal are equal, the charging means and the Each input value β and the input value of the optical means to the two means B and means C other than the unit A of the developing unit γ
While the value is fixed, the resolution input value updating operation is performed to increase or decrease the input value α to the means A according to the output of the resolution predicting means and the output of the resolution qualitative value output means. Then, after the resolution input value updating operation is executed, the density control means is executed again until the output of the resolution qualitative value output means becomes equal to the output of the resolution detection means and the reference resolution signal. 2. The image quality control device according to claim 1, wherein the image quality control device is a resolution control unit that repeatedly executes a series of operations. 5. The image quality control section is made to equalize the output of the density detection means and the reference density signal by the density control means, and then the means A
The change in the output of the density detecting means caused by increasing or decreasing the input value α to the means A, and changing the output of the density detecting means to the density before increasing or decreasing the input value α to the means A. The density control predicting means for predicting the amount of change in the input value β and the input value γ to the means B and the means C for returning to the output of the detecting means is added, and the resolution control means causes the density control means to control the density detecting means. The output and the reference density signal are made equal. After that, when the output of the resolution qualitative value output means is not the output that the output of the resolution detection means and the reference resolution signal are equal, the input value α to the means A is set to the output of the resolution prediction means and the resolution qualitative value. A resolution input value updating operation for increasing or decreasing is performed according to the output of the value output means, and the input value β and the input value γ to the means B and the means C, respectively.
Performs a density input value restoration operation of increasing or decreasing according to the output of the density restoration prediction means, and executes the resolution input value updating operation and the density input value restoration operation. Further, the density control means is executed again, and a series of operations is repeatedly executed until the output of the resolution qualitative value output means becomes an output that the output of the resolution detection means and the reference resolution signal are equal. The image quality control device according to claim 4. 6. The transfer means transfers the visible image formed by the developing means onto a transfer belt set to a predetermined transfer voltage, and the density detecting means charges and exposes a reference density patch,
Development, the transfer means detects the output density of the image formed on the transfer belt, the line width detection means, the reference line width patch image formed on the transfer belt by the charging, exposure, development, transfer means 4. The image quality control device according to claim 1, 2 or 3, wherein the line width of the image is detected. 7. A transfer means transfers a visible image formed by a developing means onto a transfer belt set to a predetermined transfer voltage, and a density detecting means charges and exposes a reference density patch,
The output density of the image formed on the transfer belt by the developing and transferring means is detected, and the resolution detecting means sets the resolution of the image formed on the transfer belt by the charging, exposing, developing and transferring means to the reference resolution patch. 6. The image quality control device according to claim 4, wherein the image quality control device detects the image quality. 8. The reference density signal has a width between the reference density upper limit value and the reference density lower limit value, and the density qualitative value output means compares the reference density signal with the output of the density detection means. Then, when the output of the density detecting means is larger than the reference density upper limit value, a qualitative value that the output of the density detecting means is larger than the reference density signal is obtained. When the output of the density detecting means is smaller than the lower limit of the reference density, the density of the output of the density detecting means is equal to the reference density signal. The qualitative value that the output of the detection means is smaller than the reference density signal is output, claim 1, claim 2, claim 3, claim 4, claim 5, claim 6 or claim 7. of Image control device. 9. The reference line width signal has a width sandwiched between a reference line width upper limit value and a reference line width lower limit value, and the line width qualitative value output means detects the reference line width signal and the line width. When the output of the line width detection means is larger than the reference line width upper limit value, the qualitative value that the output of the line width detection means is larger than the reference line width signal is set to the line When the output of the width detection means is smaller than the reference line width upper limit value and larger than the reference line width lower limit value, the qualitative value that the output of the line width detection means and the reference line width signal are equal to each other is the line width. The qualitative value that the output of the line width detection unit is smaller than the reference line width signal is output when the output of the detection unit is smaller than the reference line width lower limit value. The image control device according to claim 3 or claim 6. 10. The reference resolution signal has a width between the reference resolution upper limit value and the reference resolution lower limit value, and the resolution qualitative value output means compares the reference resolution signal with the output of the resolution detection means. If the output of the resolution detecting means is larger than the reference resolution upper limit value, a qualitative value that the output of the resolution detecting means is larger than the reference resolution signal is set, and the output of the resolution detecting means is set to the reference resolution upper limit value. If it is smaller and larger than the reference resolution lower limit value, a qualitative value that the output of the resolution detecting means is equal to the reference resolution signal is set, and if the output of the resolution detecting means is smaller than the reference resolution lower limit value, the resolution is set. The qualitative value that the output of the detection means is smaller than the reference resolution signal is output, and the qualitative value is output. Image control device. 11. A reference density patch is a high density and low density 2 patch.
The image control device according to claim 1, claim 2, claim 3, claim 4, claim 5, claim 6, or claim 7, which is one of the following. 12. The reference patch group is in a non-image part, claim 1, claim 2, claim 3, claim 4,
The image control device according to claim 5, claim 6, or claim 7.