JPS6159970A - Color correcting system in color electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To improve the color reproducibility of a color copying picture by applying the masking method to a color electrophotographic copying system and applying color correction digitally so as to attain proper color correction without increasing the size of the copying machine. CONSTITUTION:When an original is read by a color solid-state image pickup element, an output of the element is separated at each color of color separation, becomes digital signals RD, GD, BD and inputted to an operation processing circuit 100. A switch SW is thrown to the position of C1 and a Bk (a binary signal representing whether a picture belongs to a neutral section or a color picture section) from the operation processing circuit 100 to a memory 112. Then the lighting of an eraser 181 is controlled by a control circuit 114 via an eraser drive circuit 116 to erase a neutral latent image. Then the switch SW is thrown to the positions of terminals B1, A1 to generate sequentially a magenta latent image and an yellow latent image. The signals MD, YD from the circuit 100 are multi-value signals including masking information, they are collated with the content of a storage circuit 108 to generate a binary signal deciding whether or not erasing is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color correction method applicable to a color acupuncture copying machine.

(Prior Art) A color electronic copying system using a cursor/process is well known.A typical process of such a color electronic copying system is as follows.

Is the light gap between the color document and the uniformly charged photoconductive photoreceptor a red filter? irradiated through. Exposing the photoreceptor to light through a filter in this manner is called color separation exposure of a color original. In addition, the static latent image formed as a result of this color separation exposure is
1) Call it an elephant. Now, the color separation a1 image formed by the above color separation exposure is a color that is complementary to the red color, that is, the color of the filter used during the color separation exposure, that is, 7
Toner colored in 7/ (hereinafter referred to as 77/ toner)
The resulting 7-color visible line is transferred onto a white recording sheet such as paper.

Next, color separation exposure using a green filter is carried out, and the formed color separation layer r image is visualized with magenta toner, which is a complementary color of green. - transferred onto the paper.

Next, color separation exposure using a back color filter and development using yellow toner are performed, and one visible image of yellow color is also transferred onto the recording sort.

In this way, the 717-color visible image, the magenta-colored visible image, and the yellow-colored visible image are sequentially transferred onto the recording notebook and overlap each other, reproducing the color image of the color original. becomes.

It should be noted that in this specification, when referring to the back of a counterfeit, this color refers to a color that should be accurately called back purple.

Furthermore, in the following description, when distinguishing between individual color separation layers obtained by color separation exposure.

The color separation layer (elephant) is distinguished by the color of the toner to be developed. For example, the color separation layer [elephant] to be developed by the Noah/toner is distinguished by the color of the toner to be developed. A latent image is a color-separated latent image formed by color-separating exposure using a red filter.
@, Yellow Sub 11! are color separation layers formed by color separation exposure using a green filter and a back color filter, respectively.

Now, in the color electronic copying system as described above, the color of the color copy (elephant) is determined by the combination of toner colors on the recording sheet. Therefore, the relative amount of each color toner making up the color copy image is If the target distribution is different, the color shading i of the color copy image will be different.

Therefore, in order to stabilize the color tone in the color electronic copying system as described above, an operation called color balance is performed. However, even if this color copying operation is performed ideally, the colors of the color copy image will not accurately reproduce the colors on the color original.The reason for this is the color of the toner. .

Among the six types of toners mentioned above, consider shear/toner as an example. A buried cyan toner is a toner that completely absorbs red light and completely reflects green light and background color, but in reality, cyan toner does not completely absorb red light. It does not absorb it, but reflects it to a certain extent, and also partially absorbs green light and backlight. Real magenta toner and yellow toner are also different from Riso's magenta toner and yellow toner. Taking cyan/toner as an example again, real cyan toner absorbs background color light and green light. This means that it can be considered that the actual 77/toner contains magenta toner and toner as impurity components.

Therefore, when a shear/submarine image is developed with a shea/toner of a real color, the visible image obtained includes magenta toner.

This means that yellow toner is also included as an impure component. If you think about it this way, for example, when you correct the visible f-elephant of magenta color to the visible f-elephant of Noah's seven colors, you should already consider the visible f-elephant of cyan color. 7i! If the magenta toner component as an impurity contained in ■ is subtracted in advance from the maze/red color visible image, the color reproduction of the back color copy image 1 image as a mixture of cyano and maze/red color can be achieved. can be improved.

This way of thinking and thinking (and therefore the operation to improve the color reproducibility of color copied images) is called color correction.Color correction is originally a concept in the technical field of color printing, and there is a method to actually perform it. A masking method is known.Therefore, by applying this masking method to a color electronic copying system, it can be expected to improve the color reproduction of color copied images.

Conventionally, as an example of applying a masking method to a color electronic copying system, a method disclosed in Japanese Patent Laid-Open No. 53-3252 is known. However, implementing this method requires a pair of photoconductive photoreceptors, which increases the size of the copying machine.

(Objective) The object of the present invention is to apply the above-mentioned masking method to a color electronic copying system and perform color correction digitally, which is a completely new method.
The objective is to provide a color correction method.

〔composition〕

The present invention will be explained below.

The color correction of the present invention has the following five steps, namely:
There are five steps: a reading step, a masking amount determination step, and a partial erasing step with the eraser.

The reading process is a process of color-separating a color document and reading it with a solid-state sensor. Color separation here refers to the color ring'
The light image of I'+":4 is passed through a color separation filter,
This means that one image is formed in the light receiving area of the solid-state sensor.

Solid-state photography [reading by an elephant element can be done using a filter for color separation and a solid-state i'ji ('J'). Solid-state imaging is performed using a device at a good temperature.

The reading process may be carried out simultaneously with the initial G'] color separation on the photoreceptor VC, i.e., in the above example, the exposure to form a cyan latent image, or alternatively, It may be performed prior to exposure.

The masking amount determination step is a step in which the amount of masking is determined based on the image information read in the above reading step.

The second step of this maskinder lid closing process is mainly processed by a microcomputer. The masking rate may be determined by calculating according to a predetermined calculation, or by selecting a value that has been calculated and stored in advance.

In the partial erasure step, the color separation latent image is partially erased at an erase rate determined according to the masking amount determined in the masking amount determination step. This partial erasure is performed by an eraser using an area modulation method.

As the eraser, a dot light emitter array is used. The dot light emitter array is a combination of an LED array, a dot fluorescent tube array, etc., which will be described later, and a one-element system. As the imaging optical system, a convergent light transmitter array or a roof mirror lens array is used.

Here, the amount of masking and its determination will be briefly explained.

Now, the colors of the filters used for color separation are α and β.

Let γ be γ, and their complementary colors ξ and η. In other words, for example, if color separation is performed using an α-color filter, ξa
I& is formed.

If we represent this ξm@ with the actual ζ toner, then η toner,
ζ toner also enters as an impurity component.

Therefore, when developing with η latent re & W and real η toners, we take into consideration the η toner components that have adhered as impurities from the previous development with ζ toner, and reduce the amount of η toner adhering to the ηa image. do. How easy it is to see,
ξal゛ as a reference, and a coefficient A? smaller than 1? multiplied by

Continuing on, there is one zeta submerged image (although it is actually done with toner),
Since ζ toner is also included as an impurity in each part I of ζ toner and η toner, a coefficient B(<1)t! is added to this using the η latent image as a reference. - only the multiplied value.

ζ Adhesion of toner? I see less.

The above coefficients A and B will be referred to as masking rates. The masking rates A and B are determined when one color ξ, η, and ζ are determined, and may be calculated theoretically or determined experimentally.

When ξ is shear/, η is magenta, and ζ is yellow, in the case of color printing, A is generally KO,,5B, and B is often 0.45.

Above, 8m1 elephant multiplied by masking rate A ↓ and
The value obtained by multiplying η11 by B can be used as the masking amount. In this specification, the masking amount is an amount that serves as an indicator of how much the latent image is erased, and is not necessarily expressed as the same amount.

In the present invention, a color original is separated into colors and read by a solid-state sensor. If the color of the filter used for color separation at this time is α, the output from the solid-state camera element at this time corresponds to ξm. Therefore, if we call the above output the ξ output, the product of this ξ output and A is:
It can be used as the masking amount for the η latent image.

This will be explained below using a specific example.

FIG. 1 schematically shows only the main parts of an example of a color electronic copying machine to which the present invention is applied. Since it is an explanatory diagram,
The relative size relationship between the dimensions of each part is not necessarily accurate.

In the figure, reference numeral 10 indicates a one-component SVt photoreceptor. This photoreceptor 10 is drum-shaped and can move in the direction of the arrow \1m+.

A charger 12, an eraser 18. Developing device 20. 22. 24. 26, a holder 28, a static eliminator 62, and a cleaner 34 are provided.

Reference numeral 16 indicates a document placement glass, on which the document 0 to be copied is placed.
is placed flatly on this document placement glass 16.

The exposure optical system designated by reference numeral 14 includes a mirror 140, a plane mirror 141, a roof mirror 142 . 143, lens 14
4. Consists of a filter device F.

Further, the reading optical system indicated by reference numeral 40 includes a half mirror 401, a lens 402 . It is composed of a single-plate color solid-state image sensor 406, and a half mirror 401.
is arranged in the exposure optical path of the exposure optical system 14.

To reduce the illumination of document 0, light the lamps 140, move the lamps 140 and the plane mirror 141 to the left as a unit, and at the same time move the roof mirror 142.

It is moved to the left at a moving speed that is 1/2 of the moving speed of the plane m 141. Then, the lens 144 scans the document 00.
, the illumination section ■ forms an image on the photoreceptor 10, and the image of the document 0 by the lens 402 is the color solid h IJJ transducer element 6.
Connect it to the light receiving part of.

Filter device fiIt, F is red filter F'
a green filter F2, if color filter F3
, = Utralde/Entifilter F4
(hereinafter referred to as ND filter F4), and each filter can be selectively placed in the light exposure of the exposure optical system.

The eraser 18 includes an LED play 181 and a convergent light transmission play 182.

The holder 28 is drum-shaped and is for holding plain paper S (hereinafter referred to as transfer paper S) as a recording sheet, and rotates in the direction of the arrow following the 100 rotations of the seven photosensitive members. do.

In addition, in Figure 1 VC, code 60 is a transfer device, code 66
indicates a fixing device. Further, reference numeral 42 indicates a reference loss plate.

Before entering into a detailed description of the present invention, a color electronic copying process using the apparatus shown in FIG. 1 will be briefly explained.

When the original O is placed on the original placing glass 16 and the apparatus is operated, the photoreceptor 10 rotates in the direction of the arrow.

A charger 12 uniformly charges ten photoreceptors.

Note that the photoconductive layer of the photoreceptor 10 is formed of a photoconductive material having panchromatic spectral sensitivity, such as As2Se3.

Subsequently, the original O is scanned by the exposure optical system 14. At this point, a red filter F1 is placed in the exposure optical path of the filter device ff&Fc, so that the document 0 is color-separated and exposed by the red filter F1, and a cyan latent image is formed on the photoreceptor 10. To go. Simultaneously with the exposure of the photoreceptor 10, the original 0 is transferred to the reading optical system 4.
Read by 0.

Document 0 has one achromatic image and a color image on a white background. The white area and one achromatic image on the original O are called a neutral area.

The color image portion and the neutral portion of the document 0 are identified by the output of the color solid-state sensor 1#Z element 405 of the reading optical system 40. This identification will be described later.

Once the neutral portion of the original 40 has been identified, the layer image portion corresponding to this neutral portion is erased by the eraser 18. Therefore, the result of this erasure, photoreceptor 10
A shear/latent image corresponding only to the color image □□□ is left on top. This shear/latent image is visualized by the developing device 20 using cyan toner. In this way, visible gaps of Noah's seven colors are formed on the photoreceptor 10, and the photoreceptor 100
Move with rotation.

The transfer paper S, which is a recording sheet, is clamped at the leading end by the holder 28 according to the 7th question of the process, and
8, the holder is held so as to wrap around the surface of the holder, and is superimposed on the visible gaps of 717 colors on the photoreceptor 10. This transfer transfer machine 30 charges the holder 60 by discharging a polar charge that electrically attracts the visible gap, and transfers it onto the visible first transfer paper S using electric force. Visible [After the image transfer, the photoreceptor 10 is neutralized by a static eliminator 62, and is removed by a cleaner 5.
Step 4 removes residual toner.

The green filter F2 of filter arrangement F is then placed in the exposure optical path and the same process is repeated. A maze latent image is formed on the photoreceptor 10;
The neutral portion of the latent image is erased by the eraser 18, and at the same time, partial erasure is performed by area modulation at an erase rate depending on the masking area.

Thereafter, this Maze/Ria image is displayed in the Maze/Tatner, which is placed in the visualization device 22. The maze/red color visible image thus obtained on the photoreceptor is transferred onto the transfer paper S so as to be superimposed on the Noah seven-color visible image.

Next, the back filter F4 of the filter device F is installed in the Fukimoto path of the exposure optical system, and the same process as above is repeated. The yellow latent image formed on the photoreceptor 10 is erased in the ↓reneutral portion by the eraser 18, and the color image portion is partially erased in an area modulation manner at an erase rate depending on the masking area. After that, the yellow sub 1 elephant.

The image is developed by the developing device 24 using a yellow toner, and the resulting yellow visible image is transferred onto the transfer paper S.

Next, the ND filter F4 of the filter device F is installed in the exposure optical path, and the above process is repeated. This time, an electrostatic latent image corresponding to the document OK is formed, but the color image corresponding portion of this electrostatic latent image is erased by the eraser 18. Thus, on the photoreceptor 10, a latent image corresponding to the neutral area (hereinafter referred to as "neutral 1 all order") is formed.
Only now, this neutral latent image is the duty order device 26.
Developed using black toner.

When the black visible image thus obtained is transferred onto the transfer paper S, the transfer paper S is separated from the holder 28 and sent to the fixing device 16, where the toner 1 is fixed and the device outputs it as a color copy. Expelled outside.

The above is an outline of the color electronic copying process in the example of the apparatus shown in FIG.

The present invention in such a color copying system will be described in detail below.

First, a single-plate color solid-state image sensor and an eraser will be explained.

In the color solid-state image sensor 403 in the reading optical system 40, a large number of minute light-receiving elements are closely arranged in one row and form a spear.
Arranged in the direction perpendicular to the drawing in the figure. Each light receiving element corresponds to an image element of □μm square on the original O. In other words, information within an area of μm is converted into a signal.

Each photodetector is covered with a tiny filter. The colors of these filters are
There are six types: red, green, and blue.

They are arranged cyclically in order of dorsal temperature.

Now, when we look at the neighboring 39M photoelectrons, one of these 0 electrons is a red filter? It is covered with
The other one is covered with a green filter, and the remaining one is covered with a blue filter.

These three light receiving elements correspond to one pixel on the document. Therefore, the image information of one pixel can be color-separated into red, green, and back and converted into a signal.

The size of one pixel is 125 μm×125 μm.

On the other hand, the LED array 181 of the eraser 18 has 125
Minute light-emitting elements having a light-emitting area of square μm are closely arranged in a direction perpendicular to the drawing of FIG. 1, and these light-emitting elements can be used in any combination to emit light.

Now, when one of the light emitting elements (hereinafter abbreviated as LED) is made to emit light, the focusing light transmitter array 18
An image is formed on the photoreceptor 10 by the imaging action of 2. Therefore,
When one LED emits light, the latent 1 portion of one pixel is erased.

Next, first, reading of document 0 will be explained.

In Figure 1, the standard @ scale indicated by the symbol Otsu 2 is:
In this example, there are 16 levels of gray scale. The density values of this standard density plate 42 are shown in Figure 2.

Yield value is from i, ao (black) to 0.05 (white)
It is divided into 16 stages. The numbers 1 to 16, which correspond to the 9M values, will be referred to as density numbers.

The density number 1 corresponds to white, and the density number 16 corresponds to black.

In Figure 2, reference numeral 403F indicates the filter arrangement of the color solid-state image sensor 406. R10,
B means red, green, and blue, respectively. The bottom chart in Figure 6 shows the output values of the color solid-state camera [Zoutsuko 405?] when each density on the reference plate 42 is read. It shows. For example, "red" indicates the output value Y that has been color-separated by a red filter.

For example, the output value for a density value of 1.4 (#[Equation 16) is 0
．． It is 04. Note that the output f values separated by the red, green, and evening color filters are not necessarily the same value due to the spectral characteristics of the color photographing element, but are treated as the same here. It's hot.

Since it is possible to electrically equalize the output values of each of these color separations, film properties are not lost even under such circumstances.

Now, on a white background, as shown in Figure 3 of Takumi, there are chromatic color images of yellow, red, maze/li, blue, soar/green, and one achromatic color image of black and gray. Assume that there is. The white background and the achromatic image are neutral parts.

When this document 0 is read by the color solid-state image sensor 406, the color-separated output values of each color image are shown in (II) in FIG.
When these output values are expressed as density numbers, they become as shown in Figure 6 (I).

Here, a description will be given of how to separate the color image portion and the neutral image portion of the @draft O taken from K, J, and so on.

Figure 5 (]l) can be thought of as representing the first image of manuscript O in terms of acquisition and relief.

Further, as described above, in the color solid-state image sensor 403 Vc, one pixel corresponds to six adjacent light receiving elements, and these light receiving elements each have red, green, and blue filters.
It is covered.

Therefore, in each pixel, the frequency of the 'rm sludge separated by red, green, and back filters is NR.

NG, NB and Tsugi, NR = NC) and NC)
Only at the =NB edge, the pixel is assumed to be a pixel in the neutral section, and in other cases, the pixel is assumed to be a pixel in the 19th section of the color image.

In this way, if you know that a certain pixel is a pixel in the neutral area, eraser LE corresponding to this pixel
By emitting light at D', the latent image in that pixel portion can be erased.

The same applies to the color image portion.

Next, determination of the amount of masking will be explained.

For the sake of concreteness of explanation, masking group A mentioned earlier.

The value of B is set as A = 0.38 and B = 0.45.

In the example just described, criterion I! Since the density is standardized in 16 levels, the color separation density of the image on the original document is all set at one of these 16 levels.

So, each of the 16 levels of criteria! 0.6 per degree
If you graph the results multiplied by 8 and multiplied by 0.45, you get something like the one shown in Figure 1,3Jr4.

Now, the numbers in the red column of Figure 6 (1) indicate manuscript O.

This is the output of the color solid-state sensor when the colors are separated and read using a red filter, and should correspond to the latent image. This output is corrected to the reference density according to the correspondence in Figure 1IF3, and, If we multiply that by 0.68 based on Figure 5, we get something like the O-1 table.

1 Table Next, based on Figure 6 and Figure 2 of Sai, the results of color separation decoding using the green filter are expressed in terms of standard yield.
This is the number in the standard density change column in Figure (1) K. Fang 5 (
The number under this standard disparagement column in 1) is
This is the number in the bottom column of the table, and this number is the magenta subt
This is the masking amount for a.

In order to see which phase change erase is performed depending on the amount of masking, in Figure 5 (1), calculate what percentage of the reference density the amount of masking (second column) corresponds to. ,
This is the number in the 54th ti4 ( ) "Lameter column" in Figure 5 (1). t"11 For example, in the area corresponding to the yellow image of document 0, it is sufficient to erase 24%. However, in reality, it is difficult to erase in 1% increments, so here we will correspond the parameters and erase rates as shown in Fig. 5 (n) VC, and erase in 5 stages. Consider the case of doing this. The value obtained for this j5 is the erase rate shown in FIG. 5(1).

In Figures 1 and 5 (Ill), the reference density in the first column indicates the reference density value of the original that has been color-separated and decoded using a blue filter. This corresponds to yellow acid [elephant].

Column J-2 in the same figure is the value obtained by multiplying the standard concentration corresponding to column 1 of Figure 1.5 (1) by 0.45, and this is the amount of masking for the yellow latent [elephant]. becomes. The parameters and erase rates in FIG. 5(][) were calculated using the same 1)E as in FIG. 5(1).

Figure 6 shows a method of erasing according to the erase rate determined as described above. ) Four square pixel arrays are used as one unit for erasing. When erasing 25%, erase r8 of m1 by one pixel, and each time the erase rate increases by 25, 1 pixel is erased.
The erased surface is expanded pixel by pixel. 7 in 316 diagrams
The portion where the edges are marked indicates the latent image portion that has not been erased.

Now, let's look back at what we've covered so far and summarize it.

First, by reading the reference density plate, the correspondence between the 16 levels of reference density and the output of the color solid-state image sensor is determined. Then, the original is read. Here, any single pixel on the manuscript? Thinking about it, this one pixel is separated into red, green, and kidney color by six adjacent light receiving elements in the color solid-state photography one-quadrant and read, and from the output, the reference density for each color separation is determined. We'll find out. The reference density when the above one pixel is separated into red, green, and blue is X,
Suppose that they are Y and Z. At this time, the masking amount for maze/phosphoric acid 1 is 0.38x, and the masking amount for yellow 1 layer is 0.45Y. The individual loose rate for each 0.38X latent image of maze/yellow is the parameter xloo.

Correspondence between 0.45Y −x ioo and erase rate (Figure 6 (l[))
Determined by In this way, the erase rate for one pixel of interest is determined, and four pixels including this one pixel are treated as one unit, and erase is performed by emitting light from the corresponding LED of the eraser.

Here, the meaning of reading the board once as a reference will be explained.

The output of a color solid-state image sensor varies by ↓°C depending on the brightness of the light source, dirt on the optical system, etc. Therefore, when reading a document, just because the output is the same does not mean that the same density is always being read. By correctly connecting the output and the reference density, the degree of color separation of the original can be properly determined. However, since the brightness of the light source, dirt on the optical system, etc. change relatively slowly over time, reading the base IAK dial may be performed for each copy, but it may be read periodically. Or (-1, it can be done only as needed.

The process of calculating the erase rate by performing calculations on the output of the color solid-state camera 1-quadrant is performed by a microcomputer.
It can be done with In the above example, the reference IJk degree value was used to calculate the amount of masking, but since the output of the solid-state image sensor corresponds to the cloudiness value, the amount of masking may be calculated using the output.

By the way, since the amount of masking is determined by the relationship between the color-separated readout outputs, these values should be memorized in advance.

In the off diagram, 4- in R indicates the density number when color separation is performed with a red filter, and the G column indicates the density number when color separation is performed with a green filter. Each number is the same as in Figure 5 (1). Corresponds to the number of Fang 3.

For example, if we look at the spine image on a document, whether it is color-separated with a red filter or a green filter, the number of layers is 16'''C'', so the amount of masking at this time is , immediately known as 68%, Figure 6 (II)
You can immediately know the erase amount of 50.

Similarly, the value of the masking amount based on the relationship between the number of times when color separation is performed using a green filter and the number of times when color separation is performed using a blue filter is calculated using a microconobuter. The masking amount may be read out from the stored content according to the reading result.

In the above explanation, 1. The masking amount displayed in % is a-5
Erase in 5 stages according to the relationship (1ffill)
However, the erase rate can also be changed to 6 or more levels. For example, let's consider a case where the temperature is changed in 16 steps as shown in Table 2 below.

In this case, as a method for performing area modulation erasing, there is a method using a well-known dither matrix or submatrix.

For example, (Iff) in Figure 8 indicates a dither matrix. This dither matrix corresponds to 4 rows and 4 columns of pixels. Now, assuming that the masking amount of these 4 rows and 4 columns of pixels is 26%, the erase value is 4 from Table 2. this? It is shown in Figure 8 (II).

The LED is then turned on when the erase value is greater than or equal to the dither matrix value.

In Figure 8 (Figure 1'), the white circles indicate the pixels that emit light from the LED.

Figure 8 (l is the submatrix of 2 rows and 2 columns, 2 rows and 2 columns
It shows the mother matrix combined into columns. If you use this mother matrix instead of a dither matrix, L
The pixels that emit light from the ED look like the white circles in Figure 9 (IY).

In the previous example, to obtain the masking amount, the masking ratios A and B are 0.38. 0.45' was used.

However, as described above, the masking amount is an amount that serves as a guide for determining the erase rate, and there are various ways to determine this amount. An example of a method for determining the amount of masking without using the masking rate will be described below.

In Table 3, the 1st column, that is, the top column, shows the relative output voltage of the color solid-state camera 1 corresponding to this basic sensitivity. The value is shown in square display.The conversion level when AD converting this relative voltage 1 series is 1 (.) and 16 as shown in columns 3 and 6.

Table 4 Table 4 displays the color image area of manuscript O in red (R) and green (G).
), after color separation and reading with the filter on the back (B),
It shows the AD conversion level of the image sensor output.

Table 5 Table 5: °C, number 1 in column 6.16.9.14.1
0.14.15 is the number in the G column in the 4th table, and should correspond to magenta m@. For example, if we focus on the color cyan, it shows a high density of 9 even when it is separated with a green filter, so if we use magenta toner at the current level, the color will be mixed, 71.
7 Colors Crab and Crab Matama 5゜ Therefore, by subtracting the constant from column R of Table 4, the density of cyan becomes equal to the density of cyan in Column 1 of Table 5, which corresponds to magenta color 1. If we consider this, we find that the above constant should be chosen as 4.

Column 22 of the Fang 5 table shows the number obtained by subtracting 4 from Column 1 (R column) representing Fang 4, which gives the amount of mask/da.

Column 6 of Fang 5 is the number of Column 2 of Fang 5 subtracted from the number of Fang 1, and this number is a parameter that gives the erase rate.

Table 6 The correspondence between this parameter and the erase rate is given in Table 16. The bottom column of Table 5 gives the erase rate.

Table J-7 shows the same content in degrees Celsius for the color separation below the blue filter.

In this case, magenta has a high α degree, so when it is reproduced with yellow toner, the color of the maze/iriirocho image appears to be crab.

Therefore, color separation density using a green filter (column G in Table 4)
The masking amount is 1 subtracted by 2 (column 2 of the 7th table), and this is made into a parameter (〕・column 6 of the 7th table) 3.6
In correspondence with the table, the erase rate determined is the value at the bottom of the off table.

Color correction using Tables 3 and 5 and Tables 1 and 7 improves the reproducibility of cyan, magenta, and yellow, but the reproducibility of red, for example, becomes insufficient. In this case, to improve the reproducibility of red, for example, maze/resistance [elegant, yellow;
50chi, maze/ri; mouth%.

Shear: 75%, Back: 50%, Green: 75cm, Red: 0
Erasing was performed at a ratio of 25 cm, violet, and 0% yellow to the yellow latent image.

Maze/Li; 75% cyan, 100% against blue, green: 2
It is better to erase at 5% $; 50%, violet; 100%.

FIG. 319 shows a block diagram of an example of a circuit for implementing the present invention.

Referring to Figure 1, the original O is a color solid-state image sensor 40.
6, the output of the element is separated for each color of the color separation and becomes a digital signal Ro, Go,,B.

and is input to the arithmetic processing circuit 100. R8, C)
o and Bo are color separation decoding signals of red, green, and blue, respectively.

At the same time as the original O is read, the photoreceptor 10 is exposed and
A latent image is formed.

The switch Sw is first closed to the terminal C1. No. 100 BK is generated from the ten arithmetic processing circuits.

In this signal B, a certain @1 is a binary signal depending on whether it is a neutral part or a color image part, and takes 1 when it is a neutral part and 0 when it is a color image [image part]. This signal BK is stored in the memory 112K, and the control circuit performs alignment with the cyan eraser and controls the light emission of the eraser 181 via the eraser drive circuit 116. As a result, the latent portion corresponding to the neutral portion, that is, the neutral latent 1 image, is deleted from the Soar/a1 image.

If a maze/rea image is formed, press the switch Sw.
is closed to terminal BI Vc. At this time, the arithmetic processing circuit outputs a multivalued signal Mn. This multilevel signal includes information regarding the amount of masking. This signal is input to the comparator 106, and upon comparison with the contents of the storage circuit 108, a binary signal M is generated which determines whether or not to erase the pixel. This signal M is
1 for neutral part and 1 for erase
, otherwise takes 0. With this signal M, the neutral fu image is erased from the maze/not latent image, and the maze/fu image is
+7-) Erasing for color correction is performed on the layer image.

Similarly, when a yellow latent image is formed, switch S
w closes to terminal A1.

The arithmetic processing circuit 100 outputs a multivalued signal Yo including masking amount information, and inputs it to the comparator 102 .

The comparator 102 compares the contents of the memory circuit 104 with the signal Yo, and generates a signal Y which is 71 for the neutral section and color correction erase and 0 for the others.

As a result, the neutral latent image is erased from the yellow latent image residue, and 2) erasing for color correction is performed.

Finally, when an electrostatic latent image is formed for a color image that is not color separated, switch Sw is closed to terminal D1.

The 2-short signal Bx output from the arithmetic processing circuit 100 is inverted by the inverter 110 and input to the memory 112. Therefore, in this case, the latent image portion corresponding to the color image will be erased from the latent image.

(Effects) As described above, according to the present invention, a novel color correction method for a color electronic copying machine can be provided. Since this method uses a one-color correction eraser and digitally performs the correction, it is possible to perform appropriate color correction without increasing the size of the copying apparatus.

[Brief explanation of the drawing]

Figure 1J11 (English) is an explanatory diagram showing only the essential parts of an example of a color electronic copying apparatus to which the present invention is applied; Figures 9 and 9 are block diagrams showing an example of a circuit for implementing the present invention. 0...Original, 18...Eraser, 406...Color solid-state photography l. Procedural Amendment November 22, 1981 Patent Application No. 181459 1981 Name of Complete Name Color Correction Method for Color Electronic Copying Machine 3 Person Making Amendment Relationship with Case Patent Applicant Name Name (674) Ricoh Co., Ltd. 4th generation
Address: 4-5-4 Kyodo, Shatagaya-ku, Tokyo "
Detailed Description of the Invention” II! 5 and drawing 6 Contents of the amendment (1) There is one side surface in front of r143J in line 5 on page 11 of the specification.

Claims (1)

[Scope of Claims] A reading step of color-separating a color document and reading it with a solid-state image sensor; and a step of determining a masking amount for a color-separated latent image to be masked based on the image information read in the reading step; A step of partially erasing the color separation latent image to be masked using an area modulation method using an eraser using a dot light emitter array at an erase rate according to the masking amount determined in the above step. , Color correction method for color electronic copying machines.