JP2956366B2 - Line width measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line width measuring device required for controlling image density and line width in an electrophotographic process.

[0002]

2. Description of the Related Art With the rapid progress of OA, a copying machine, a printer and a facsimile for obtaining high-quality images are strongly demanded. Under such demands, it has been possible to measure the density of a copied image and control the image density. (For example, Japanese Patent Application Laid-Open No. 55-15185, Japanese Patent Application No. 2-202180) However, although there is a density measuring device for measuring the density of a copied image, a simple line width for measuring the line width of a copied image is available. Since there was no measuring device, it was not possible to control the line width to realize a higher quality image.

An example of a conventional line width measuring apparatus will be described below with reference to the drawings. FIG. 7 is an overall view showing an example of a conventional line width measuring device.

In FIG. 7, reference numeral 2000 denotes a micro concentration detector, 2002 denotes an object to be measured, 2004 denotes a movable table,
6 is a density value storage means, 2008 is a density comparison means, 201
0 is a line width calculation means.

A conventional line width measuring apparatus includes a micro-density detector 2000 for detecting the density of a minute area,
02, a moving table 2004 that moves at a constant speed, a density value storage unit 2006 that stores the detection value of the micro density detector 2000 at fixed time intervals, and a density comparison unit 2008 that checks whether the density is higher or lower than the reference density. The line width calculation means 2010 examines the data in the density value storage means of the density comparison means 2008 and counts the number of portions where the density is higher than the reference density or the portion where the density is lower than the reference density is continuous. The line width was measured from the number and the speed of the moving object. Therefore, the device was very large and complicated.

[0006]

In the conventional line width measuring apparatus, the apparatus is large and complicated, so even if it can be used for image quality evaluation, it is difficult to mount it on a copying machine because of its size and cost. It was impossible.

[0007]

In order to solve the above-mentioned problems, a line width measuring apparatus according to the present invention comprises a charging means for charging a photoreceptor to a predetermined charging voltage, a charging means for charging a document on a document table to a predetermined exposure amount. Exposure means for creating a latent image on the photoconductor by projecting in the
Developing means for creating a visible image with a developer set to a predetermined developing bias voltage for the latent image, and transfer means for transferring the visible image to a transfer sheet; In the electrophotographic process in which the line width is controlled by the charging, exposing, and developing means, the electrophotographic process includes at least one reference line width patch including a high density portion and a low density portion placed on the platen, The reference line width patch detects a line width from a visible image formed on the photoconductor by the charging, exposing, and developing means. In addition, the line width measuring apparatus of the present invention includes a charging unit for charging the photosensitive member to a predetermined charging voltage, and an exposure unit for projecting a document on a document table with a predetermined exposure amount to form a latent image on the photosensitive member. Developing means for forming a visible image by using a developer set to a predetermined developing bias voltage for the latent image; transferring means for transferring the visible image to a transfer sheet; high density and low density of the copied image And an image quality control unit for controlling a line width by the charging, exposing, and developing means in the electrophotographic process, wherein at least one reference comprising a high-density part and a low-density part placed on the platen After the image quality control unit controls the high density and the low density of the copied image, the reference line width patch is formed on the photosensitive member by the charging, exposure and developing means. Concentration detector to detect the average concentration of And has a means for determining the line width with respect to the average density.

[0008]

According to the present invention, a line width measuring apparatus for easily measuring a line width can be provided by the above-described structure, and the line width of a copied image can be controlled, thereby realizing a high quality image.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A line width measuring apparatus according to one embodiment of the present invention will be described below with reference to the drawings.

As a first embodiment of the present invention, a line width can be easily measured by using a grid-like reference line width patch and measuring the average density of the toner image of the reference line width patch with a density detector. And a line width measuring device.

FIG. 1 is an overall view showing a configuration of a line width measuring apparatus according to a 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.

FIG. 2 shows the reference line width patch 124 in FIG.
FIG. In FIG. 2, reference numeral 500 denotes a high density part, and 502 denotes a low density part.

FIG. 3 is a detailed explanatory diagram of the line width detector 128 in FIG. In FIG. 3, reference numeral 510 denotes a concentration detector,
512 is a multiplier.

The operation of the above-configured line width measuring apparatus will be described below with reference to FIGS. 1, 2 and 3.

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 each photoconductor 106 in the image portion, and the effective light energy EBG corresponding to the density DBG is given in the background portion (background portion). The surface potential of the photoconductor 106, which was uniformly V0 before exposure, 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. ing. The photoconductor surface potential when no light is received by the exposure subsystem 102 is VDDP. Corresponding to the surface potential of the photoconductor 106 based on the toner concentration TC of the toner 108 and the tribo TB, and various setting parameters of the developing device (sleeve rotation speed, distance between the sleeve and the photoconductor 106, magnetization pattern, bias voltage VBIAS, etc.) The toner amount is developed 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. The operation of such an electrophotographic process is the same as the conventional method, but in the conventional method,
Although the reference patch is only the reference density patch, in this embodiment, the reference line width patch 124 is added. And
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 reference line width patch 124 and the line width detector 128 will be described. As shown in FIG. 2, the reference line width patch 124 has a high density portion 500 and a low density portion 502 configured in a lattice shape. At this time, as shown in FIG. 3, the line width detector 128 detects the average density of the grid-like toner image 126 formed on the photoreceptor 106 by the density detector 510. The line width is measured by multiplying the line width conversion coefficient by the multiplier 512. This is because the image quality control unit 130 first controls the output image density of the high-density reference density patch 114 and the output image density of the low-density reference density patch 116 to the desired density, that is, the reference density signal. I do. At this time,
Since the densities of the high-density portion and the low-density portion of the grid-like toner image 126 formed on the photoreceptor 106 also become the desired densities,
The focus is on the fact that the average density changes as the line width changes. That is, the average density is increased as the line width increases, and the average density decreases as the line width decreases.

As described above, by measuring the average density using the same detector as the density detector 112, the average density can be easily converted into a line width, and the line width can be easily measured. Therefore, the line width can be controlled by the image quality control unit 130 using the measured value of the line width, so that a higher quality image can be obtained.

Assuming that the mounting direction of the reference line width patch 124 is the direction of the grid line as the rotation direction of the photosensitive member 106, the exposing means makes the reference line width patch 124
Can be fixed to an arbitrary point on the reference line width patch 124 without scanning and projecting the image on the photoconductor, thereby forming a grid-like latent image on the photoconductor. Therefore, the line width can be measured more easily.

Next, the line width measurement accuracy is as follows. When a grid-like reference line width patch as in the first embodiment is used, the number of lines per unit length is increased to increase the number of edges. ,
Although it can be improved, the line thickness that the electrophotographic process can produce on the photoreceptor is also limited.

In such a case, as a second embodiment of the present invention, there is provided a line width detector for measuring a line width with high accuracy using a dither-like reference line width patch.

Hereinafter, a line width measuring apparatus according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is an overall view showing a configuration of a line width measuring apparatus according to a 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
, An image quality control unit; 424, a reference line width patch; 426, a toner image for the reference line width patch 424;
428 is a line width detector.

FIG. 5 shows the reference line width patch 424 in FIG.
FIG. In FIG. 5, reference numeral 520 denotes a high density portion, and 522 denotes a low density portion.

FIG. 6 is a detailed explanatory diagram of the line width detector 428 in FIG. In FIG. 6, reference numeral 510 denotes a concentration detector,
532 is a multiplier.

The operation of the line width measuring apparatus configured as described above will be described below with reference to FIGS. 4, 5 and 6.

First, the operation of the electrophotographic process is the same as that of the first embodiment. In the first embodiment, the reference line width patch is on the grid. Patch 424 is dithered. Then, similarly to the first embodiment, a toner image 426 of the reference line width patch 424 is formed on the photoconductor 106.

Next, the reference line width patch 424 and the line width detector 428 will be described. As shown in FIG. 5, the reference line width patch 424 includes a dot-shaped high density portion 52 on the low density portion 522.
0 is a dither-like patch uniformly arranged. At this time, the line width detector 428, as shown in FIG.
A density detector 510 detects the average density of the dither-shaped toner image 426 formed on the line 06 and a line width conversion coefficient is multiplied by a multiplier 532 to measure the line width. is there. This is because the image quality control unit 130 controls the output image density of the high-density reference density patch 114 and the output image density of the low-density reference density patch 116 to be the desired density, that is, the reference density signal. I do. At this time, the densities of the high-density portion and the low-density portion of the dither toner image 426 formed on the photoreceptor 106 also become the desired densities. Here, the dithered patch has more edges than the lattice patch,
The effect of the thickening and thinning of the line increases. Therefore, attention is paid to the fact that the average density greatly changes as compared with the grid-like patch due to the change of the line width.

As described above, by using the same detector as the density detector 112 to measure the average density of the visible image on the photoreceptor of the dither-like reference line width patch, it can be easily converted to the line width. The line width can be measured easily and with high accuracy. Therefore, the line width can be controlled with high accuracy by the image quality control unit 130 using the measured value of the line width, and a higher quality image can be obtained.

[0032]

As described above, according to the present invention, a charging means for charging a photosensitive member to a predetermined charging voltage, and a latent image is formed on the photosensitive member by projecting a document on a document table with a predetermined exposure amount. Exposure means, developing means for creating a visible image of the latent image with a developer set at a predetermined developing bias voltage, and transfer means for transferring the visible image to a transfer sheet, the density of the copy image And an electrophotographic process for controlling the line width of a copied image by the charging, exposing and developing means, wherein at least one reference line width patch composed of a high density portion and a low density portion placed on the platen is provided. The line width can be easily measured by detecting the line width from the visible image created on the photoreceptor by the charging, exposing, and developing means with the reference line width patch. In addition to controlling the density of the output image The line width of the output image becomes possible to control,
High quality output images can be realized.

[Brief description of the drawings]

FIG. 1 is an overall view showing a configuration of a line width measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a detailed explanatory diagram of a reference line width patch in FIG. 1;

FIG. 3 is a detailed explanatory diagram of a line width detector in FIG. 1;

FIG. 4 is an overall view showing a configuration of a line width measuring apparatus according to a second embodiment of the present invention.

FIG. 5 is a detailed explanatory diagram of a reference line width patch in FIG. 4;

FIG. 6 is a detailed explanatory diagram of a line width detector in FIG. 4;

FIG. 7 is an overall view showing an example of a conventional line width measuring device.

[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 124 Line width detector 130 Image quality control unit 424 Reference line width patch 426 Toner image 428 line for reference line width patch 424 Width detector 500 High density part 502 Low density part 510 Density detector 512 Multiplier 520 High density part 522 Low density part 532 Multiplier 2000 Micro density detector 2002 Measurement target 2004 Moving table 2006 Density value storage 2008 concentration comparison means 2010 line width calculation means

Continuation of front page (56) References JP-A-58-115453 (JP, A) JP-A-4-3185 (JP, A) JP-A-63-158573 (JP, A) JP-A-59-136754 (JP) , A) Fully open 1987-169355 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/00 303 G03G 15/36 G03G 21/00 370-540 G03G 21/02 -21/04 G03G 21/14 G03G 21/20 B41J 3/00

Claims (7)

(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; transferring means for transferring the visible image to a transfer sheet; and charging the high density, low density and line width of the copy image An electrophotographic process including an image quality control unit controlled by exposure and development means, wherein at least one reference line width patch including a high density portion and a low density portion is provided on the platen. After the image quality control unit controls the high density and low density of the copy image, the reference line width patch is charged, and the average density of the visible image created on the photoconductor by the exposure and development unit is detected. An average concentration detector and the average concentration A line width measuring device comprising a line width calculator for calculating a line width by multiplying a line width conversion coefficient. 2. The line width measuring apparatus according to claim 1, wherein the reference line width patch is a reference patch in which a high density portion and a low density portion are in a grid pattern. 3. A reference line width patch is a dither-like reference patch in which high density points are uniformly arranged on a low density area, or a low density point is uniformly arranged on a high density area. 2. The line width measuring apparatus according to claim 1, wherein the reference patch is a dithered reference patch. 4. An image forming apparatus comprising: at least two reference density patches having a high density and a low density, which are uniform densities, placed on a platen; and an average density detector charges each of the reference density patches. 2. The line width measuring apparatus according to claim 1, wherein the density of the visible image group formed on the photoconductor by the exposure and development means is shared with at least one of a density detector group for individually detecting the density. 5. The line width measuring apparatus according to claim 1, wherein the reference line width patch is located in a non-image portion. 6. A charging device for charging a photoconductor to a predetermined charging voltage, an exposure device for projecting a document on a document table with a predetermined exposure amount to form a latent image on the photoconductor, and Developing means for creating a visible image with a developer set to a predetermined developing bias voltage; transferring means for transferring the visible image to a transfer sheet; and charging the high density, low density and line width of the copy image An electrophotographic process including an image quality control unit controlled by exposure and development means, wherein at least one reference line width patch including a high density portion and a low density portion is provided on the platen. After the image quality control unit controls the high density and low density of the copy image, the reference line width patch is charged, and the average density of the visible image created on the photoconductor by the exposure and development unit is detected. An average concentration detector and the average concentration A line width measuring device having means for calculating a line width. 7. The line according to claim 6, wherein the means for calculating a line width with respect to the average density is a line width calculator that calculates a line width by multiplying the average density by a line width conversion coefficient. Width measuring device.