JP2614373B2 - Color balance adjustment 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 color balance adjusting device for a full-color copying machine or the like.

[0002]

2. Description of the Related Art Conventionally, in a full-color copying machine, when adjusting the balance of a color-recorded image, a serviceman uses a gray-patch manuscript having a gradation and a toner to a certain level of gray-patch. Adjust so that-is recorded. In this case, the copy is repeated while adjusting the color balance so that the patch color becomes gray while adjusting the toner amounts of the yellow, magenta, and cyan colors.

[0003]

However, in the above-mentioned conventional method, since the colors of yellow, magenta and cyan are in a very delicate relationship, a slight shift in the balance of one color results in a large color balance. Therefore, there is a problem that the serviceman cannot adjust smoothly. Therefore, in the above-mentioned conventional method, since the serviceman actually performs a large number of copies, the number of copies is increased, and the developer and the photoreceptor are worn out, fatigued, and the cost is increased. Also, a very long adjustment time is required at the user site, giving a bad impression to the user.

As an apparatus for automatically adjusting the color balance, each toner image of yellow, magenta, and cyan is recorded on a photoreceptor by automatically changing a lamp voltage, and each toner density is adjusted. In this case, since each color of yellow, magenta, and cyan is recorded, there is a problem that the adjustment time, power consumption, and consumables increase. Also, you
If the user mistakenly activates the color balance adjustment mode, the recording paper will not be ejected even if the copier operates for a long time, giving the user anxiety.

The present invention has been made in view of the above-mentioned conventional problems, and provides a color balance adjusting apparatus capable of automatically adjusting a color balance with a small amount of power and consumables in a short time. The task is to

[0006]

In order to achieve the above-mentioned object, a color balance adjusting apparatus according to the present invention illuminates an image with a light source and exposes the illuminated image to a photoreceptor to color.
A color image forming apparatus for forming electrostatic latent images corresponding to first, second and third colors for forming an image and visualizing each of the formed electrostatic latent images as a toner image An infrared sensor for detecting the toner density of a toner image formed for one of the first, second, and third colors, and changing the light amount of a light source. Then, the optimum light amount for the one color is obtained from the relationship between the toner density detected for the one color and the light amount, and the optimum light amount for the other two colors is determined as a predetermined function of the obtained optimum light amount. And automatic adjustment means required.

[0007]

According to the present invention, the infrared sensor comprises the first and second infrared sensors.
And a toner formed for one of the third colors
When the toner density of the image is detected, the automatic adjusting means obtains the optimal light quantity for the one color from the relationship between the toner density detected for the one color and the light quantity by changing the light quantity of the light source. . Here, the optimum light amounts for the first, second, and third colors have a fixed relationship with each other for the same color image forming apparatus. Therefore, such a relationship may be obtained in advance as a predetermined function. it can. Therefore, as long as the optimum light amount for one color is obtained as described above, the optimum light amount for the other two colors can be obtained very simply by a simple calculation as a predetermined function of this one color. As a result, the color balance can be automatically adjusted in a short time with a small amount of power and consumables.

The following examples of the present invention will clarify such effects of the present invention, and will clarify other effects of the present invention.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a color balance adjusting device according to the present invention. FIG. 2 is a schematic configuration diagram showing a color copying machine provided with the color balance adjusting device of FIG.
FIG. 3 is a graph showing the characteristics of the infrared sensor shown in FIGS. 1 and 2, and FIG. 4 is a graph for explaining the operation of the color balance adjusting device of FIG.

First, referring to FIG. 2, a schematic configuration of a color copying machine provided with a color balance adjusting device of the present embodiment will be described. In FIG. 2, a transparent document table 11 for mounting a document P is fixed on an upper surface of the machine frame by an opaque sheet metal 12, and a document on the document table 11 is placed on the document table 11. An opaque document holding plate 13 for holding P is provided to be openable and closable. For example, a document size or the like is printed on the upper surface of the sheet metal 12, and at least one of the lower surface of the sheet metal 12 and the lower surface of the document pressing plate 13 is configured as a white surface by being printed in white.

An exposure optical system 14 for scanning an image of the original P is disposed below the original mounting table 11. The exposure optical system 14 has a home position below the sheet metal 12 and a sub-scanning position. Light source lamp 14a for illuminating the lower surface of the document P via the transparent document table 11, and the light reflected by the document P on the photoreceptor 16 as shown by a dashed line in FIG. A plurality of reflectors 14b for guiding to the exposure position A;
It comprises a color separation filter 14c having three primary color filters of red, green and blue, and an imaging lens 14d.

The photosensitive member 16 is formed in a belt shape and is rotatable in a counterclockwise direction in the figure by a driven roller 17 and a driving roller 18. A charging charger 19 is provided upstream of the exposure position A. Are located. In this embodiment, yellow, magenta, and cyan are used as examples of the first, second, and third colors for forming a color image.
Downstream of the exposure position A, a yellow developing tank 20Y, a magenta developing tank 20M, and a cyan developing tank 20Cy are sequentially arranged.
Further, a black developing tank 20B for performing black-and-white copying or four-color color copying, an intermediate transfer member 21 to which a toner image on the photoreceptor 16 is transferred intermediately, a cleaning unit 22, and a discharging lamp 23 are located.

The intermediate transfer member 21 is a black film in which carbon is dispersed in a polycarbonate resin, and is formed in a belt shape like the photosensitive member 16 and has first to third rollers 24a to 24a.
It can be rotated clockwise in the figure by c, and is pressed against the photoreceptor 16 by a transfer roller 25. Transfer ro
An infrared sensor 26 used for color balance adjustment in this embodiment is disposed downstream of the
The roller 24c is pressed against a transfer roller 28 for transferring the toner image on the intermediate transfer member 21 to the transfer paper 27. As the infrared sensor 26, a sensor that detects only a wavelength of 750 nm or more is selected. FIG. 3 shows such an infrared sensor
Shows 26 example characteristics.

The transfer paper 27 is set in advance in a cassette 30 at the lower right in FIG.
The sheet is conveyed to the position of 33, and is conveyed to the position of the transfer roller 28 by the timing roller 33 so as to match the toner image on the intermediate transfer member 21. Transfer paper 27 onto which toner image has been transferred
Is transported to the fixing device 35 by the transport belt 34, and the toner
After the image is fixed by the fixing device 35, the image is discharged. Therefore,
The image of the original P is copied onto the transfer paper 27 by the charging-exposure-development-transfer process.

The automatic adjusting device 51 constitutes an example of an automatic adjusting means. As will be described later, the toner density y measured by the infrared sensor 26 is inputted, and the lamp voltage x of the light source lamp 14a is determined to be yellow. -Automatically adjusts the color balance of magenta and cyan.

In the above configuration, the ordinary color
When copying is performed, the image of the document P is scanned three times, separated into three colors by the color separation filter 14c, and an electrostatic latent image of each color is formed on the photosensitive member 16. The electrostatic latent images of the respective colors on the photoreceptor 16 are complementary colors of the respective colors of the color separation filter 14c, i.e., yellow developing tank 20Y, magenta developing tank 20M, and cyan developing tank.
Each toner is visualized by each toner by 20 Cy, and each toner image is transferred onto the intermediate transfer member 21. Note that the black color developing tank 20B and the infrared sensor 26 are not used for normal color copying, and only the black developing tank 20B is used for black and white copying.

Next, a detailed configuration of the color balance adjusting device 50 of the present embodiment will be described with reference to FIG. This color
The balance adjusting device 50 includes an automatic adjusting device 51 for adjusting the exposure voltage of the light source lamp 14a and a surface potential changing device for changing the charging potential on the photoconductor 16 by controlling the voltage applied to the charging charger 19. It has 55.

The automatic adjusting unit 51, color - a comparator circuit 52 for comparing the concentration y and the reference value A _0, color - - at the time of balance adjustment, toner is detected by the infrared sensor 26 yellow set during balancing -, memory for storing magenta, the optimum value x _y for each lamp voltage cyan, x _m, the x _c
53, the normal three-color color - During copying, an exposure voltage control circuit 54 which applies the exposure voltage optimum value x _y memory 53, x _m, the exposure voltage x corresponding to x _c to the light source lamp 14a. still,
At the time of color balance adjustment, by controlling the drive voltage of the charging charger 19, the surface potential of the photoconductor 16 is set to a surface potential Vo set externally as a value higher than the surface potential during normal image formation. change.

Next, referring to FIGS. 1 and 4, the detailed operation of the color balance adjusting device 50 constructed as described above will be described by adjusting yellow and calculating using the value. The case of adjusting magenta and cyan will be described as an example.

[0020] First, the surface potential change device 55 is charged Cha - changing the photosensitive member 16 charged potential V ₀ which by controlling the voltage applied Ja 19. Next, after the exposure voltage control circuit 54 applies a voltage of, for example, 50 V to the light source lamp 14a, the exposure voltage control circuit
The toner concentration is read through the infrared sensor 26 after being raised twice. In this case, the color separation filter 14c shown in FIG.
Is a blue filter, and a yellow developing tank
20Y is driven.

Accordingly, at least one of the white images on the lower surface of the sheet metal 12 and the lower surface of the document pressing plate 13 is illuminated by the light source lamp 14a with ten kinds of light amounts, and is guided to the exposure position A of the photosensitive member 16 via the blue filter. The electrostatic latent image is
Formed on top. Then, the electrostatic latent image is visualized by the yellow developing tank 20Y, the toner is transferred onto the intermediate transfer member 21, and each toner density Sn (n = 1 to 10) is detected by the infrared sensor 26. Is done.

The color balance adjusting device 50 is provided with the toner
The concentration Sn and the applied voltage Ln of the light source lamp 14a are stored correspondingly, and similarly, the applied voltage of the light source lamp 14a is changed from 50 V to 3
A total of ten toner concentrations Sn increased by V are fetched, and the applied voltages Ln are stored correspondingly.

Next, the approximate expression Sn = a / Ln + of the least squares method is obtained from the ten toner concentrations Sn and the applied voltage Ln.
b (a, b: constants) are obtained, and the yellow lamp voltage VY is obtained.
And the toner concentration Ly. Here, yellow,
The magenta and cyan lamp voltages V _Y , V _M and V _C are
As shown in FIG. 4, they can be expressed by Equation 1, Equation 2 and Equation 3 (where a to f are constants, N = 1 to 5). Thus, yellow if determined constants a to f -, magenta, each lamp voltage V _Y of cyan, V _M, V _C and toner - density Ly,
Lm and Lc can be obtained. .

[0024]

V _Y = a · Ex · N + b

[0025]

[Number 2] _{V M = c · Ex · N} + d

[0026]

Equation 3] _{V C = e · Ex · N} + f , where constant a~f is not able to determine the absolute value differs for each copying machine due to variations in the surface potential and an exposure optical system 14 of the photoreceptor 16, Slopes a, c, e and intercepts b, d,
f has a fixed relationship as shown in Equations 4 and 5 regardless of the copying machine (where A to F are constants).

[0027]

## EQU4 ## a: c: e = A: C: E

[0028]

[Mathematical formula-see original document] b: d: f = B: D: F Therefore, if constants A to F are obtained in advance by experiments,
Yellow balance a and intercept b in the balance adjustment mode
, The other magenta and cyan constants can be obtained by the following equations.

[0029]

C = a · C / A

[0030]

[Mathematical formula-see original document] e = a * E / A

[0031]

## EQU8 ## d = b.D / B

[0032]

F = b · F / B Each of the yellow, magenta and cyan lamp voltages V _Y ,
V _M, V _C and toner - density Ly, Lm, the optimum value x _y of the lamp voltage by Lc, x _m, x _c is calculated memory 53
Is stored in the normal three-color color - During copying, the exposure voltage control circuit 54 applies the optimum value x _y, x _m, the exposure voltage x corresponding to x _c to the light source lamp 14a.

Therefore, according to the above-described embodiment, since the other magenta and cyan constants can be obtained by calculating the slope a and the intercept b of the yellow, the yellow and magenta can be obtained as in the conventional example. Therefore, it is not necessary to form an image for obtaining a constant for each color of cyan, so that the color balance can be automatically adjusted in a short time with a small amount of power and consumables.

[0034]

As described in detail above, according to the present invention, the infrared sensor can detect one of the first, second and third colors.
When the toner density of the toner image formed for one color is detected, the automatic adjusting means changes the light intensity of the light source by changing the light intensity of the light source and the light intensity of the one color. Find the optimal amount of light for each color,
Further, as a predetermined function of this one color, the optimum light quantity for the other two colors can be obtained very simply by simple calculation. As a result, the color balance can be automatically adjusted in a short time with a small amount of power and consumables.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a color balance adjusting device according to the present invention.

FIG. 2 shows a color provided with the color balance adjusting device of FIG.
FIG. 1 is a schematic configuration diagram illustrating a copying machine.

FIG. 3 is a graph showing characteristics of the infrared sensor shown in FIGS. 1 and 2;

FIG. 4 is a graph for explaining the operation of the color balance adjusting device of FIG. 1;

[Explanation of symbols]

 14a Light source lamp 16 Photoconductor 20Y, 20M, 20Cy Developing tank 26 Infrared sensor 50 Color balance adjustment device 51 Automatic adjustment device

Claims (1)

(57) [Claims] An image is illuminated by a light source, and the illuminated image is exposed to a photosensitive member to form an electrostatic latent image corresponding to first, second, and third colors for forming a color image. And a color for visualizing each of the formed electrostatic latent images as a toner image.
A color balance adjustment device used in the image forming apparatus, wherein the infrared sensor detects a toner density of the toner image formed for one of the first, second, and third colors; By changing the light amount of the light source, the optimum light amount for the one color is obtained from the relationship between the toner density detected for the one color and the light amount, and another two functions are determined as a predetermined function of the obtained optimum light amount. A color balance adjustment device comprising: automatic adjustment means for obtaining an optimum light amount for a color.