JP3031070B2 - Image quality control device - Google Patents

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 is a strong demand for a copying machine, a printer, and a facsimile capable of obtaining high-quality image quality. Under such demands, it has been possible to measure the density of a copied image and control the image density (for example, JP-A-55-15185 and JP-A-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, reference numeral 100 denotes 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
Denotes a document table, 200 denotes a density inspection unit, 1000 denotes an image quality control unit, and 1002 denotes a density correction unit.

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

In FIG. 7, 304 is a density qualitative value output means, 306 is a density characteristic curve qualitative value creation 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. The 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 configured as described above 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 document 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 given to the photosensitive member 106 in the image portion, and the effective light energy EBG corresponding to the density DBG is given in the background portion (background portion). V before exposure
The surface potential of the photosensitive member 106, which was 0, is attenuated by receiving the effective light energy corresponding to the document density, and reaches VIM in the image portion and VBG in the background portion when reaching the developing subsystem 104. The photoconductor surface potential when no light is received by the exposure subsystem 102 is VDDP. Toner concentration TC of toner 108 and tribo TB
And other 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 of the electrophotographic process. In the electrophotographic process, the charging sub-process, the exposure sub-process, and the developing
Through one sub-process, a toner image is formed on the photoconductor 106. Assuming that 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 photoreceptor 106,
γS is a constant determined by the parameters of the development sub-process 104, the physical properties and the degree of deterioration of the toner 108, the film thickness and the dielectric constant of the photoconductor 106, and the like. Further, the photoconductor surface potential VDDP, the effective light energy EBG, the bias voltage VB
IAS is an adjustable parameter, and by adjusting these, the output image density DS with respect to the input image density DIM
Can be adjusted. Photoconductor surface potential VDD
P cannot be directly operated, but can be indirectly operated by manipulating the inflow current Id from the charging corotron 100.

The relationship between the input image density DIM and the output image density DS is given by (Equation 1) to (Equation 3).

[0015]

(Equation 4)

## EQU1 ## The equation is obtained as shown in an actually measured density characteristic curve shown in FIG. The purpose of conventional image quality control has been to match this measured density characteristic curve with a desired target density characteristic curve. Therefore, if functions (Equation 1) to (Equation 3) representing the characteristics of the electrophotographic process can be obtained quantitatively, an 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, the light quality, etc., and γS in (Equation 3) is also a parameter of the development sub-process, and the physical properties and the degree of deterioration of the toner, the thickness and the dielectric constant of the photoconductor , It is very difficult to grasp them quantitatively and precisely.
For this purpose, for example, in Japanese Patent Application No. 2-202180, the image quality controller 1000 controls the photoconductor surface potential VDD.
The input vector X composed of P, effective light energy EBG, and bias voltage VBIAS is changed based on a qualitative model, and the measured density characteristic curve is made to coincide with the target density curve by performing translation and rotation. The qualitative model is a qualitative expression that expresses how the sign of the output value changes depending on the sign of the input vector, that is, whether the sign is positive, negative, or zero.

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

[0018]

(Equation 5)

A k-th trial is performed based on the above, 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 above is realized. At this time, the input vector storage unit 1012 stores the input unit 1010 in the k-th trial.
Stores the input vector X (k) input to the electrophotographic process as the reference input vector Xold. Prior to the first trial (initial state), an initial input vector Xini is given to the reference input vector Xold and stored. The density qualitative value output means 304 outputs an output vector Y,
A reference high-density signal Ds_ which is a desirable value of these two densities
hd and a reference output vector Yd composed of the reference low-density signal Ds_ld, and a deviation vector e,

[0022]

(Equation 7)

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

Next, density characteristic curve qualitative value creating means 306
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. The parallel movement can be described by (Equation 4).

[0027]

(Equation 8)

Can be represented by That is, (Equation 8)
Is that if the photoconductor surface potential VDDP increases, the output image density Ds
Increases, the effective light energy EBG and the bias voltage VBIAS
Means that the output image density Ds decreases. Therefore, when it is desired to increase the output image density Ds,

[0029]

(Equation 9)

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

[0031]

(Equation 10)

[0032]

[Equation 11]

[0033]

(Equation 12)

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

[0035]

(Equation 13)

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

[0037]

[Equation 14]

In the case of (Equation 10), of course, (Equation 10) to (Equation 12)
, That is, the sign is reversed. Next, the rotational movement will be described. Deriving a qualitative equation from an equation 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 of the high density portion is higher than the reference high density signal Ds_hd and the density Ds_l of the low density portion is lower than the reference low density signal Ds_ld,

[0042]

(Equation 16)

[0043]

[Equation 17]

Is as follows. Therefore, from (Table 1),

[0045]

(Equation 18)

Is as follows. Then, according to (Equation 15),

[0047]

[Equation 19]

[0048]

(Equation 20)

Is as follows. That is, it is understood that the photoconductor surface potential VDDP and the effective light energy EBG should be reduced.

Next, input change vector creating means 1014
ΔVDDP, δEBG, and δVBIAS are each set to a positive small change amount, and are output by multiplying the output of the change input qualitative value creating means 1018. That is, the first element is represented by + δVDDP, 0, −δ
Select one of VDDP and set the second element to + δ
An input change vector △ X obtained by selecting any one of EBG, 0, −δEBG and selecting one of the third element from + δVBIAS, 0, −δVBIAS is created.

Then, the input vector updating means 1016
Generates an (k + 1) th input vector X (k + 1) by adding the input change vector △ X to the reference input vector Xold, and this input is added to the electrophotographic process by the density input means 300, and the same operation is repeated. Thus, a desired image can be obtained by repeatedly learning.

A density learning end checking means 314 is provided between the density qualitative value output means 304 and the density characteristic curve qualitative value creating means 306.
If all the qualitative values, which are the outputs of 4, are 0, it is determined that the desired image has been obtained, and the learning operation ends.

[0053]

In a conventional image quality control device, the density of a copied image is controlled, so that the contrast of the density of a solid portion is good. However, when an image such as a thin line is copied, the line becomes thinner or thicker. Sometimes occurred. Further, even if an attempt is made to control the line width, the conventional control method cannot independently control the density and the line width because the qualitative expressions are the same. For this reason, there has been a problem that thin lines disappear or characters are crushed.

[0054]

In order to solve the above problems, an image quality control apparatus according to the present invention comprises a charging means for charging a photosensitive member to a charging voltage, and a method for projecting a document on a document table with a predetermined exposure amount. Exposing means for forming a latent image on the photoconductor, developing means for forming a visible image with the developer set to a predetermined developing bias voltage, and transferring the visible image to a transfer sheet And at least one reference density patch having a uniform density and at least one reference line width patch including a high density portion and a low density portion, wherein the reference density patch has a uniform density and is placed on the platen. A reference patch group having: a density detection unit that detects the output density of a visible image created on the photoreceptor by the charging, exposure, and development units of 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 photoreceptor by a step, a reference density signal, a reference line width signal, and comparing the output of the density detecting means with the reference density signal. Further, there is provided a density qualitative value output means for outputting a qualitative value indicating that the output of the density detecting means is larger, equal, or smaller than the reference density signal.

By comparing the reference line width signal with the output of the line width detecting means, a line width for outputting a qualitative value that the output of the line width detecting means is larger, equal, or smaller than the reference line width signal. A qualitative value output means, qualitatively that the output of the density detecting means increases, does not change, or decreases by increasing or decreasing respective inputs to the charging means, the exposure means, and the developing means. There is a qualitative model part that memorizes various relationships.

If the output of the density qualitative value output means is not an output indicating 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 is provided. 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 converted to the qualitative relationship of the qualitative model unit and the concentration qualitative value output means. A density input value update 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 update operation until the output of the density detection means is equal to the reference density signal; and the density control means outputs the output of the density detection means and the reference density signal. After making the input value α to the unit A increase or decrease, the change in the output of the concentration detection unit, the output of the concentration qualitative value output unit is again controlled by the concentration control unit, After returning to the output that the output of the density detection means is equal to the reference density signal, the line width prediction means for predicting the output of the line width qualitative value output means, and the density control means The output is made equal to the reference density signal.

Thereafter, if the output of the line width qualitative value output unit is not an output indicating that the output of the line width detection unit is equal to the reference line width signal, the unit B and the unit C are output.
Each of the input values β and the input value γ are fixed, and the input value α to the unit A is changed according to the output of the line width prediction unit and the output of the line width qualitative value output unit. A line width input value updating operation for increasing or decreasing is performed, and after performing the line width input value updating operation, the density control unit is executed again, and an output of the line width qualitative value output unit is the line width detection unit. And a line width control means for repeatedly executing a series of operations until the output of the reference line width signal becomes equal to the reference line width signal.

[0059]

According to the present invention, there is provided an image quality control apparatus capable of controlling the line width and the like of a copied image and generating a high quality image by controlling the line width in addition to the conventional density control. Can be done.

[0060]

DETAILED 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, reference numeral 100 denotes 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,
206 is a line width correction unit.

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

In FIG. 2, reference numeral 250 denotes a qualitative model unit, 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, 310 is The density input change vector creating means 312 is a density input vector updating means, 3
Reference numeral 14 denotes a concentration learning completion inspection unit.

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;
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
Reference numeral 6 denotes a line width change input qualitative value creating unit, 360 denotes a line width input change value creating unit, 362 denotes a line width input updating unit, and 364 denotes a line width learning end checking unit.

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 that of 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, a toner image 126 of the reference line width patch 124 is formed on the photoconductor 106.

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

In this case, first, the control command unit 15
0 will be described. The control command unit executes the density control first, executes the line width control after the density control is completed, forms a loop in which the density control is executed again, so that the density and the line width are provided together with the desired image. The control is repeated until the condition is satisfied. That is, first, the line width input means 350 which is a part of the line width correction unit 206 does not change the bias voltage VBIAS which is the input of the line width control, and the density inspection unit 200 for density control and the density correction unit 202 do not change. Is executed. Here, the density control loop will be described. Upon receiving a command from the control command section 150, the density input means 300 causes the photoconductor surface potential VDD as an input for density control.
P, an input vector composed of the effective light energy EBG,

[0071]

(Equation 21)

A k-th trial is performed based on the output vector, which is 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 above is realized. At this time, the density input vector storage means 302 stores the density input means 3 in the k-th trial.
00 is the input vector Xd input to the electrophotographic process
(K) is stored as the reference density input vector Xd-old. In the first trial, the initial density input vector Xd-ini is input from the density input means 300 and the initial line width input Xl-ini is input from the line width input means 350 to the electrophotographic process.
Before the first trial (initial state), the initial density input vector Xd-in is added to the reference density input vector Xd-old.
Give i and memorize. Here, the operations of the density qualitative value output unit 304, the density characteristic curve qualitative value creation unit 306, and the density learning end inspection unit 314 are the same as those in the conventional example. 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 prior art.
14, but here, δVDDP and δEBG are each set to a positive slight change amount and multiplied by the output of the density change input qualitative value creation means 308 and output. That is, the first element is +
A density input change vector △ Xd obtained by selecting one of δVDDP, 0, −δVDDP and selecting one of + δEBG, 0, −δEBG as the second element is created.

Then, the density input vector updating means 312
Is obtained by adding the density input change vector △ Xd to the reference density input vector Xd-old to obtain the (k + 1) th input vector Xd
(K + 1) is created, this input is applied to the electrophotographic process by the density input means 300, and the same operation is repeated. As described above, the density learning end detecting unit 314 determines that an image having a desired density is obtained, and repeatedly performs learning until the learning operation is completed, whereby an image having a desired density can be obtained.

Next, when the control command unit 150 receives a signal indicating that an image of a desired density has been obtained by the density learning end detection means 314, the line width inspection unit 20 for line width control is received.
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 that the line width Lw has been detected by the line width detector 128 when it is determined that an image having a desired density has been obtained and the learning operation has been completed. At this time,
The line width qualitative value output means 354 compares the line width with a reference line width signal Lwd which is a desirable value of the line width, and outputs a qualitative value [e3] of the deviation value e3.

The theoretical expressions of the photosensitive member surface potential VDDP, 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)

The following can be derived. 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 obtained by qualifying (Equation 23).

[0081]

(Equation 24)

The following relationship is obtained. However, since this qualitative equation is the same as (Equation 8), the density and the line width cannot be controlled independently as it is. The inputs for controlling the density are the photoconductor surface potential VDDP and the effective light energy EBG.
Even if the line width control input is separated from the bias voltage VBIAS, the density and the line width interfere, so after controlling the density to the desired density, change the bias voltage VBIAS to control the line width. Then, of course, the density will deviate from the desired density.

Then, the line width predicting means 260 calculates (Equation 4)
From the theoretical equation of (Equation 23) and using the equation in which the density is fixed by the photoconductor surface potential VDDP and the effective light energy EBG, the density is controlled by the density correction unit 202 to a desired density.
When the bias voltage VBIAS is changed in order to control the line width, the density deviating from the desired density is changed again to the density correction unit 20.
The change in the line width after controlling the density to a desired value can be predicted by using FIG. When the input for controlling the line width is a bias voltage VBIAS, an equation in which the density is fixed by the photoconductor surface potential VDDP and the effective light energy EBG, that is, the line width Lw is obtained from the theoretical equations (Equation 4) and (Equation 23). When a qualitative equation is obtained from the relational equation between the bias voltage and the bias voltage VBIAS,

[0084]

(Equation 25)

## EQU10 ## Therefore, the line width change input qualitative value creation unit 356 outputs the bias voltage from the output of the line width qualitative value output unit 354 according to the qualitative value of the change in the line width predicted by the line width prediction 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 is output by multiplying the output of the line width change input qualitative value creating means 356. That is, + δVBI
A line width input change value ΔXl obtained by selecting any one of AS, 0, and −δVBIAS is created.

Then, the line width input value updating means 362 adds the line width input change value lXl to the reference line width input value Xl-old to create the j-th input value Xl (j), By means 350, the photosensitive member surface potential V
The input vector composed of DDP and the 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 unit 352 stores the input Xl (j) input to the electrophotographic process by the line width input unit 350 in the j-th trial as the reference line width input Xl-old. Prior to the first trial (initial state), the initial line width input Xl-ini is given to the reference line width input Xl-old and stored.

Thereafter, the control command section 150 moves to a density control loop comprising the density inspection section 200 and the density correction section 202, repeatedly executes the processing until the desired density is obtained, and the density learning end detecting means 314 detects the image having the desired density. Is received, the process again goes to a line width control loop including a line width inspection unit 204 and a line width correction unit 206 for line width control. The above series of operations are repeated until a desired line width is obtained. As described above, by repeatedly learning, it is possible to obtain an image that achieves desired density and line width. Note that a line width learning end checking unit 364 is provided between the line width qualitative value output unit 354 and the line width change input qualitative value creating unit 356, and the qualitative value output from the line width qualitative value output unit 354 is If it is 0, it is determined that the desired image has been obtained, and the learning operation ends.

Here, an example of the operation up to this point will be described.
Now, it is assumed that an image having a desired density is obtained by the density control loop as in the conventional example. However, in this case, since the inputs for controlling the density are the photoconductor 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 larger than the reference line width signal Lwd, ie,

[0090]

(Equation 26)

Then, it is necessary to reduce the line width Lw. Therefore, based on the line width predicting means, the following equation (25) is used.

[0092]

[Equation 27]

Is obtained. 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 thinner from the relational expression of (Equation 8). Then, returning to the concentration control loop again,
The image is returned to the desired density by the photoconductor surface potential VDDP and the effective light energy EBG.

As described above, by repeatedly learning a series of operations, 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 for controlling the line width is the effective light energy E
In the case of BG, when the line width is predicted by the line width predicting means 260, the line width is not uniquely determined, and it is necessary to classify the case according to the value of the input at that time. Therefore, the configuration of the line width prediction means 260 becomes complicated. Therefore, as in the first embodiment, the input for controlling the density is the photoconductor 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 that the configuration is simplified.

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

Therefore, as a second embodiment of the present invention, a change in density when the input for controlling the line width is updated in the line width control loop is predicted, and a density for canceling the 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.

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

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

In FIG. 4, reference numeral 100 denotes 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,
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 denotes a line width correction unit, and reference numeral 404 denotes a density restoration prediction unit.

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

In FIG. 5, reference numeral 200 denotes a density inspection unit;
4 is a line width inspection unit, 250 is a qualitative model unit, 260 is line width prediction means, 262 is line width control means, 300 is density input means, 302 is density input vector storage means, 310 is density input change vector creation means, 312 is a density input vector updating means, 356 is a line width change input qualitative value creating means, 40
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 and density correction section 401 for density control, and a line width inspection for line width control. It comprises a unit 204, a line width correction unit 402, and a density restoration prediction unit 404. Of the photoconductor surface potential VDDP, effective light energy EBG, and bias voltage VBIAS which are inputs to the electrophotographic process, the inputs for controlling the density are the photoconductor surface potential VDDP and the effective light energy E.
BG, and the input for controlling the line width is assumed to be the bias voltage VBIAS.

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 basic operation of the line width correction unit 402 are the same as those in the first embodiment, except that the control command unit 150 receives a signal indicating that an image of a desired density has been obtained by the density learning end detection unit 314, When a line width control loop including a line width inspection unit 204 for line width control and a line width correction unit 402 is executed,
The line width change input qualitative value creating means 356 creates a qualitative value of the bias voltage VBIAS according to the qualitative value of the change in the line width predicted by the line width predicting means 260, and
2, the bias voltage VBIAS is updated and output, and the qualitative value of the change in the line width predicted by the line width prediction unit 260 is also input to the density restoration prediction unit 404. The density restoration predicting 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 the density change, that is, in this case, the photosensitive member surface potential VDDP and the effective amount. 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 for updating. This can 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, the present invention provides a charging means for charging a photoreceptor, an exposing means, a developing means, and at least a uniform density placed on the platen in an electrophotographic process. A reference patch group having one reference density patch, at least one reference line width patch composed of a high density portion and a low density portion, and forming the reference density patch on the photoconductor by the charging, exposing and developing means Density detection means for detecting the output density of the visible image, and charging and exposing the reference line width patch, line width detection means for detecting the line width from the visible image created on the photoconductor by the developing means, ,
A reference density signal, a reference line width signal, the reference density signal, and an output of the density detection unit are compared.

The density qualitative value output means outputs a qualitative value indicating 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 to output a qualitative value indicating that the output of the line width detecting means is larger, equal, or smaller than the reference line width signal. By increasing or decreasing the input to the line width qualitative value output means, the charging means, the exposure means, and the developing means, the output of the density detecting means increases, does not change, or decreases. This is a qualitative model unit that stores qualitative relationships.

If the output of the density qualitative value output means is not an output indicating that the output of the density detection means is equal to the reference density signal, any one of the charging means, the exposure means and the developing means is used. While the input value α to the two means A is fixed, the input values β and γ to the remaining two means B and C are converted into the qualitative relationship of the qualitative model unit and the concentration qualitative value output. A density input value update 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 is changed to the output that the output of the density detection means is equal to the reference density signal. A density control means for repeatedly executing the density input value update operation until the output of the density detection means and the reference density signal are equalized by the density control means.

Thereafter, a change in the output of the density detecting means caused by increasing or decreasing the input value α to the means A is output from the density qualitative value output means again by the density control means. A line width prediction unit for predicting the output of the line width qualitative value output unit after returning the output of the density detection unit to the output that the reference density signal is equal, and the output of the concentration detection unit by the density control unit And after equalizing the reference density signal, 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, while the input value β and the input value γ are fixed, the input value α to the means A is fixed.
Is increased or decreased in accordance with the output of the line width prediction means and the output of the line width qualitative value output means.

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 equal to 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 output becomes equal, in addition to the conventional density control of the output image, the line width of the output image can also be controlled, and a high-quality output image can be obtained. Can be realized.

[Brief description of the 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. 1;

FIG. 3 is a detailed explanatory diagram of a line width inspection unit and a line width correction unit in FIG. 1;

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

FIG. 5 is a detailed explanatory diagram of a density correction unit, a line width correction unit, and a density restoration prediction unit in FIG. 4;

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

FIG. 7 is a detailed explanatory diagram of a conventional image quality control unit in FIG. 6;

FIG. 8 is a conventional image density characteristic diagram.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 charged corotron 102 exposure subsystem 104 development subsystem 106 photoreceptor 108 toner 110 document 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 Toner image for reference density patch 116 of document 122 Document platen 124 Reference line width patch 126 Toner image for 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 unit 401 Density correction unit 402 Line width correction unit 404 Density restoration prediction unit 406 Density control unit 1000 Image quality Control unit 1002 Concentration correction unit 1010 Input unit 1012 Input vector storage unit 1014 Input change vector creation unit 1016 Input vector update unit 1018 Learning end inspection unit

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03G 15/16 G03G 15/04 120 G05B 13/04 (56) References JP-A-55-15185 (JP, A) JP-A Sho 57-60348 (JP, A) JP-A-59-22060 (JP, A) JP-A-59-124358 (JP, A) JP-A-60-83975 (JP, A) JP-A-1-101564 (JP, A A) JP-A-59-115453 (JP, A) JP-A-1-101563 (JP, A) JP-A-2-149864 (JP, A) JP-A-59-174862 (JP, A) JP-A-2 -186367 (JP, A) JP-A-4-3185 (JP, A) JP-A-4-310979 (JP, A) JP-A-4-186255 (JP, A) JP-A-5-100513 (JP, A) JP-A-3-89370 (JP, A) JP-A-2-311860 (JP, A) JP-A-1-288869 (JP, A) JP-A-2-2877582 (JP, A) JP-A-1-270084 (JP, A) JP-A-63-43169 (JP, A) JP-A-5-100532 (JP, A) JP-A-3-92652 (JP) , U) Shokai Sho 55-4403 (JP, U) JP-B 63-11665 (JP, B2) JP-B 63-14349 (JP, B2) Patent 2917620 (JP, B2) (58) Int.Cl. ⁷ , DB name) G03G 15/00 303 G03G 21/14 G03G 21/00 370-540

Claims (12)

(57) [Claims] A charging unit configured to charge a photosensitive member to a predetermined charging voltage; an exposure unit configured to project a document on a document table with a predetermined exposure amount to form a latent image on the photosensitive member; Developing means for creating a visible image with a developer set to a predetermined developing bias voltage, transfer means for transferring the visible image to a transfer sheet, and uniform density placed on the platen Density detection means for providing at least one reference density patch, and detecting the output density of a visible image formed on the photoreceptor by the charging, exposure, and development means;
And at least one reference line width patch composed of a high-density portion and a low-density portion, and providing the reference line width patch from a visible image created on the photoconductor by the charging, exposing, and developing means. Line width detecting means for detecting the
Compare the output of the step with the reference density signal to determine the density of the copied image.
Controlling the output of the line width detecting means and a reference line width signal.
And an image quality control unit for controlling the line width of the copied image.
In the child photographing process, the image quality control unit compares the reference density signal with the output of the density detection unit, and determines a qualitative value that the output of the density detection unit is larger than, equal to, or smaller than the reference density signal. Comparing the output of the density qualitative value with the output of the reference line width signal and the output of the line width detection unit, and determining that the output of the line width detection unit is larger than, equal to, or smaller than the reference line width signal. a line width qualitative value output means for outputting a value, by increasing or decreasing the respective input to said charging means and said exposing means and the developing means, the output of the concentration detector is increased or not changed, Alternatively, the qualitative model part storing the qualitative relationship of decreasing, the output of the density detecting means and the reference density signal are equal.
If there is no input unit, the input value α to any one of the charging unit, the exposing unit and the developing unit A is fixed, and the input value β and the input value to the remaining two units B and C are fixed. a value gamma, the qualitative model unit density input value that or decrease or do not change increases according to the output of the qualitative relationship between the density qualitative value output means updates the dynamic of
The output is determined by the output of the density detecting means and the reference density signal.
Density control means for repeatedly executing until the output becomes equal to each other; and the density control means makes the output of the density detection means equal to the reference density signal, and then increases or decreases the input value α to the means A. The output of the line width qualitative value output unit after the change of the output of the density detection unit is returned by the density control unit so that the output of the density detection unit and the reference density signal become equal to each other is predicted. After the output of the density detecting means is made equal to the reference density signal by the density control means, the output of the line width detecting means is adjusted.
If the force and the reference line width signal are not equal, the input value β to the means B and the input value β to the means C, and the input value α to the means A while the input value γ is fixed,
A line width input value update operation for increasing or decreasing according to the output of the line width prediction means and the output of the line width qualitative value output means.
Operation, and then execute the concentration control means again,
The output of the line width detecting means is equal to the reference line width signal.
A line width control means for repeatedly executing a series of operations until the image quality is controlled. 2. When the output of the density qualitative value output means is not an output indicating that the output of the density detection means is equal to the reference density signal, the density control means keeps the input value to the developing means fixed and the charging means. And the respective input values to the exposure means, perform a density input value update operation of increasing, decreasing, or not changing according to the qualitative relationship of the qualitative model unit and the output of the density qualitative value output means, The density input value updating operation is repeatedly executed until the output of the qualitative value output means becomes equal to the output of the density detection means and the reference density signal. After equalizing the output of the density detecting means with the reference density signal, a change in the output of the density detecting means caused by increasing or decreasing the input value to the developing means is described. The output of the density qualitative value output means is again output by the density control means,
After returning the output of the density detecting means to the output that the reference density signal is equal, the output of the line width qualitative value output means is predicted, and the line width controlling means is provided by the density controlling means. After the output of the line width qualitative value output unit is not equal to the output of the line width detection unit and the reference line width signal after equalizing the output of the charging unit and the exposure unit, A line width input value updating operation for increasing or decreasing the input value to the developing unit in accordance with the outputs of the line width prediction unit and the line width qualitative value output unit while keeping the input values of the line width fixed. After performing the line width input value update operation, the density control means is executed again,
2. The image quality according to claim 1, wherein a series of operations are repeatedly performed until the output of the line width qualitative value output unit becomes an output indicating that the output of the line width detection unit is equal to the reference line width signal. Control device. 3. An image quality control section, wherein the output of the density detection means and the reference density signal are made equal by the density control means, and
A change in the output of the density detecting means caused by increasing or decreasing the input value α to the
Predicting the respective change amounts of the input value β and the input value γ to means B and means C back to the output of a previous said density detecting means for increasing or decreasing the input value α to the means A and output means out the concentration repair predicting means for adding, after the line width control unit was equal to the output with the reference density signal of said density detecting means by said density control means, the line width
If the output of the detection means and the reference line width signal are not equal,
A line width input value updating operation for increasing or decreasing the input value α to the means A according to the output of the line width prediction means and the output of the line width qualitative value output means, and
And the input value β and the input value γ to the means C increase or decrease in accordance with the output of the density restoration prediction means.
Density input value restoration to reduce or not change
Perform the operation, and then execute the concentration control means again,
The output of the line width detecting means is equal to the reference line width signal.
2. The image quality control device according to claim 1, wherein a series of operations are repeatedly performed until the operation is completed. 4. A line width detecting means for charging a reference line width patch,
Exposure, resolution detection means for detecting the resolution from the visible image created on the photoreceptor by the development means, the image quality control unit,
Compare the output of the density detection means with the reference density signal to copy
Controlling the density of the image, the output of the resolution detection means and the reference solution;
Means for controlling the resolution of a copied image by comparing it with an image signal
A is, the image quality control section, the line width qualitative value output means compares the output of the standard resolution signal and the resolution detection means, the output is greater than the standard resolution signal of the resolution detector means, equal Or a resolution qualitative value output unit that outputs a qualitative value that is small or small, wherein the line width prediction unit equalizes the output of the density detection unit and the reference density signal by density control unit, and then the charging unit and the charge unit A change in the output of the density detecting means caused by increasing or decreasing the input value α to one of the means A of the exposing means and the developing means is changed by the density controlling means to the output of the density detecting means again. The reference density
A resolution predicting means for predicting an output of the resolution qualitative value output means after returning the signal to be equal to the degree signal, wherein the line width control means controls the output of the density detection means and the reference by the density control means. after equal to the density signal, the
The output of the resolution detection means is equal to the reference resolution signal.
When there is no input unit, the input value β and the input value γ to the two units B and C other than the unit A among the charging unit, the exposure unit, and the developing unit are fixed, and the input value β to the unit A is fixed. The input value α, according to the output of the resolution prediction means and the output of the resolution qualitative value output means , performs a resolution input value update operation to increase or decrease , after that,
The density control means is executed again, and the resolution detection means
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 until an output becomes equal to the reference resolution signal . 5. An image quality control section, wherein the output of the density detection means and the reference density signal are made equal by the density control means, and
A change in the output of the density detection means caused by increasing or decreasing the input value α to the density A, and changing the output of the density detection means to the density before increasing or decreasing the input value α to the means A. A density restoration predicting means for predicting a change amount of each of 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, and a resolution controlling means is provided by the density controlling means. After equalizing the output and the reference density signal,
If the output of the image resolution detection means and the reference resolution signal are not equal,
If the input value α to the means A is increased or decreased according to the output of the resolution prediction means and the output of the resolution qualitative value output means, a resolution input value update operation is performed, and the means B and the The input value β and the input value γ to the means C increase or decrease or do not change according to the output of the density restoration prediction means.
A density input value restoration operation is performed, and thereafter, the density control means is executed again, and the output of the resolution detection means and the reference solution
5. The image quality control device according to claim 4, wherein a series of operations are repeatedly performed until the image signal becomes equal to the image signal. 6. A transfer means for transferring a visible image created by a developing means onto a transfer belt set at a predetermined transfer voltage, and a density detecting means for charging a reference density patch, exposing,
Developing, detecting the output density of the image formed on the transfer belt by the transfer means, the line width detecting means, the reference line width patch, the image formed on the transfer belt by the charging, exposure, development, transfer means 4. The image quality control device according to claim 1, wherein the line width is detected. 7. A transfer unit transfers a visible image created by a developing unit onto a transfer belt set to a predetermined transfer voltage, and a density detecting unit charges a reference density patch, exposes the reference density patch,
Developing, detecting the output density of the image created on the transfer belt by the transfer means, the resolution detecting means, the charging, exposure, development, the resolution of the image created on the transfer belt by the charging means, exposure, development, transfer means The image quality control device according to claim 4, wherein the image quality control device detects the image quality. 8. A reference density signal having a width between a reference density upper limit value and a reference density lower limit value, and a density qualitative value output means compares the reference density signal with an output of the density detection means. When the output of the density detecting means is larger than the reference density upper limit, a qualitative value indicating that the output of the density detecting means is larger than the reference density signal is set as the output of the density detecting means. If the output is smaller than the reference density lower limit, a qualitative value indicating that the output of the density detector is equal to the reference density signal is used. 9. A qualitative value indicating that an output of the detecting means is smaller than the reference density signal, and wherein the qualitative value is outputted. of Image control device. 9. The reference line width signal has a width between an upper limit value of the reference line width and a lower limit value of the reference line width, and the line width qualitative value output means outputs the reference line width signal and the line width detection signal. When the output of the line width detecting means is larger than the reference line width upper limit value, a qualitative value that the output of the line width detecting means is larger than the reference line width signal is compared with the line width detecting means. When the output of the width detecting means is smaller than the upper limit of the reference line width and larger than the lower limit of the reference line width, a qualitative value that the output of the line width detecting means is equal to the reference line width signal is determined by the line width. 3. A qualitative value indicating that an output of said line width detecting means is smaller than said reference line width signal when an output of said detecting means is smaller than said reference line width lower limit value. 7. The image control device according to claim 3 or 6. 10. A reference resolution signal having a width sandwiched between a reference resolution upper limit value and a reference resolution lower limit value, and a resolution qualitative value output means compares the reference resolution signal with an output of the resolution detection means. Then, when the output of the resolution detection means is larger than the reference resolution upper limit value, a qualitative value that the output of the resolution detection means is larger than the reference resolution signal, the output of the resolution detection means is the reference resolution upper limit value If the output is smaller than the lower limit of the reference resolution, a qualitative value indicating that the output of the resolution detector is equal to the reference resolution signal is used. The qualitative value that the output of the detecting means is smaller than the reference resolution signal is output. Image control device. 11. A reference density patch comprising two high density and low density patches.
The image control apparatus according to claim 1, 2, 3, 4, 5, 6, or 7, wherein: 12. The method according to claim 1, wherein the reference patch group is located in a non-image portion.
The image control device according to claim 5, 6, or 7.