JPS5926946B2 - electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color electrophotographic method, and particularly to a color electrophotographic method that achieves well-controlled color separation image reproduction and enables multicolor reproduction faithful to the original. It is.

Conventionally, color reproduction used in the fields of printing, silver halide photography, and electrophotography is based on a subtractive color method.

Normally, for this color reproduction, cyan, magenta, yellow
These are the three primary colors, and dyes, pigments, etc. having each of these colors are used alone or in combination to reproduce the desired color. In order to achieve complete color reproduction using the three primary colors, the cyan, magenta, and yellow coloring materials are basically red light in visible light,
It is necessary to have ideal spectral reflection (or transmission) characteristics that completely absorb only green light and blue light in just the right amount.

However, for practical printing inks, color photographic materials, electrophotographic toners, and other coloring materials, their spectral reflection (or transmission) characteristics are as shown in Figure 1, and yellow absorbs unnecessary light. Although small, cyan absorbs a considerable amount of green light and a certain amount of blue light, and magenta absorbs a considerable amount of blue light. In other words, cyan can be considered to be the same as ideal cyan mixed with a considerable amount of magenta and a certain amount of yellow. Furthermore, magenta can be considered to be the same as ideal magenta mixed with a considerable amount of yellow. Therefore, as long as a coloring material that absorbs unnecessary light is used as described above, accurate color reproduction cannot be obtained. A masking method has been put into practice in the printing field as a method for correcting errors due to color material characteristics. A positive mask method used in color printing masking will be explained as an example. Color correction is performed by superimposing a positive image (positive mask image) of a light density created from other color separation negative images on a separated negative image of an adult fish that requires correction at the stage of producing each color plate. This method requires two extra image forming steps in order to obtain a good one-color separated image, and in order to completely correct the image,
Since it is necessary to strictly control the image forming conditions in each step, it is extremely complicated and time-consuming, and it is difficult to ensure completeness.

Even in electrophotography, the conventional masking method, in which a mask image is superimposed on the original image and image exposure is carried out, requires an extra process, just as in printing, and has many practical problems, so it is not desirable. It's not a thing.

In view of the above points, it is an object of the present invention to provide a color electrophotographic method in which color correction can be easily performed and a good color separation image can be formed depending on the coloring material. The electrophotographic method of the present invention that achieves the above object uses a photoreceptor having an insulating layer, a photoconductive layer, and an electrically conductive layer, and a multilayer film is applied to the surface of the photoreceptor charged with a predetermined polarity through a desired developing complementary color filter. a step of irradiating the color original light image, a step of reducing the charged charge of the predetermined polarity at the same time as or before and after the irradiation of the light image, and a filter that transmits the light image of the portion of the multicolor original to be developed with the development color. The method includes the step of irradiating a multicolor original optical image onto the surface of the photoreceptor through a step to form an electrostatic latent image in accordance with a desired developed color.

Hereinafter, the present invention will be explained using specific examples with reference to the drawings.

2. FIGS. 1 to 5 are diagrams illustrating the steps of forming an electrostatic latent image according to the present invention.

1 is an explanatory diagram of the structure of photoreceptor A, in which a1 is a conductive support, A2 is a photoconductive layer formed on the conductive support a1, and A
3 is an insulating layer uniformly formed in close contact with the photoconductive layer A2.

2 to 4 or 2 to 5 exemplify the process of forming an electrostatic latent image of a color-corrected color image on the photoreceptor configured as described above and the charging pattern of the photoreceptor; Layer A3
Step 3 is a step of uniformly primary charging the surface; step 3 is a step of simultaneously performing first color separation image exposure through a green filter and AC corona charge removal; step 4 is a second step through a red filter. In place of step 4, step 5 shows a step of performing a second color separation image exposure through a red filter and full-surface exposure with a small amount of exposure.

The potential characteristics of the surface of the insulating layer of photoreceptor A in each of the above steps are as shown in FIG.

When this electrostatic latent image is developed with magenta toner, the electric potential of the electrostatic latent image is equal to the red light absorption area of the multicolor document 2 (the area that should ideally be developed and visualized with cyan toner). It decreases depending on the amount. Therefore, when a multicolor copy image is obtained, the cyan color that is developed in the red absorption area of the multicolor original 2 is
The amount of magenta toner superimposed on the toner is reduced in proportion to the amount of cyan toner, making it possible to faithfully reproduce the colors of the original. For example, if a blue filter is used for the first color separation image exposure of the present invention and a green filter is used for the second color separation image exposure, and the electrostatic latent image at that time is developed with yellow toner. In this case, the potential of the electrostatic latent image decreases according to the amount of green light absorbed by the green light-absorbing portion of the multicolor original (the portion that should ideally be developed and developed with magenta toner on the photoreceptor). Therefore, when a multicolor copy image is obtained, the amount of yellow toner that overlaps the magenta toner developed in the green light absorbing portion of the multicolor original decreases in proportion to the amount of magenta toner. , it is possible to faithfully reproduce the colors of the original.

In steps 2 to 4 of FIG. 2, first, when the surface of the insulating layer A3 of the photoreceptor A is positively charged (A) using a corona discharger 13, for example, if the photoconductive layer is of N type, the conductive support A1 side is charged. Negative H charges are injected and captured at the interface between the photoconductive layer A2 and the insulating layer A3 or at a portion inside the photoconductive layer A2 close to the insulating layer A3.

Through this process, the surface potential of the insulating layer A3 increases with charging time, and exhibits the characteristics shown in FIG. 3Vp. Of course, the charging may be carried out by means of electrodes instead of corona discharge. Note that this charging step can be performed in a bright place. The charging polarity in the charging step is that of the photoconductive layer A.
If 2 is an N-type semiconductor, it is preferably charged positively (A), and if it is a P-type semiconductor, it is preferably charged negatively (→).

However, this is not absolute, and an electrostatic latent image can be formed even if the material is charged with the opposite polarity to the above case. Next, the first color separation image exposure is performed, and for ease of understanding, a multicolor original 2 having the colors and brightness of magenta, cyan, black, and white is used to expose the insulating layer surface of the photoreceptor A.
An electrostatic latent image (this latent image is developed with magenta toner) is color-corrected according to the amount of red light absorbed in the red light-absorbing portion of the multicolor original 2.

The following steps will be explained using the case of obtaining ) as an example. Figure 2, 3
As shown in FIG. 2, a multicolor original 2 is illuminated by a white light source 3. This reflected light from the original provides primary color separation image exposure to the photoreceptor A through a green filter 19, which is a complementary color to magenta. At the same time, AC corona static elimination 14 or charging with the opposite polarity of the primary charging is performed. At this time, since the magenta and black parts of the multicolor original 2 absorb a considerable amount of green light, almost no reflected light passes through the green filter 1, and the charge on the surface of the insulating layer A3 of the corresponding part of the photoreceptor A is retained. It remains as it was. Furthermore, since the white portion of the original reflects most of the green light and transmits it through the green filter, the charge on the surface of the insulating layer A3 of the corresponding portion of the photoreceptor A is discharged. On the other hand, since the cyan portion of the document absorbs green light to some extent, the amount of reflected light passing through the green filter is small, and a portion of the charge on the surface of the insulating layer A3 of the corresponding portion of the photoreceptor A is retained. That is, by the corona charge removal performed simultaneously with the exposure of the original image through the filter 1, all or most of the positive charges on the surface of the insulating layer 3 corresponding to the white portion are removed.

The amount of charge removed depends on the AC corona charge removal time and strength, but in this case, the resistance of the photoconductive layer 2 decreases due to photoimage exposure and becomes conductive, and the photoconductive layer A2 becomes conductive due to the charging.
Negative (C) charges captured at the interface between the photoconductive layer A2 and the insulating layer A3, or at a portion of the photoconductive layer A2 close to the insulating layer A3, become free, decrease as the surface charge of the insulating layer A3 decreases, and become large. The charge on the part is released to the conductive support 1. Therefore, the surface potential of the white portion of the insulating layer A3 decreases with the corona charge removal time and takes on the characteristics shown in FIG. 3 Vw. On the other hand, in the portions corresponding to the magenta and black portions of the document, positive (
-I-) is reduced by static elimination, but the amount is small.

This is because the resistance of the photoconductive layer A2 is high due to the negative H charge that was captured on the rising surface of the photoconductive layer A2 and the insulating layer A3 or in the inner part of the photoconductive layer A2 close to the insulating layer A3 due to primary charging. The positive (-1-) charges on the surface of the insulating layer A3 are restrained by the negative H charges, so that the degree of discharge is reduced. In the part corresponding to the cyan part of the original, the surface of the insulating layer is positive (
b) The amount of charge removed is greater than the magenta and black areas of the original, but less than the white area of the original.

In this way, the insulating layer A is lower in the center and black areas of the original than in the cyan and white areas of the original.
There is a large amount of positive (A) charge remaining on the surface of 3, but at the same time, a large amount of negative H charge is captured in the photoconductive layer A2, which is in the state of X, so the field due to the surface charge of the insulating layer A3 is photoconductive. Interacting with the negative charges trapped in the layer A2, the internal field is quite large, but the external field due to surface charges becomes extremely small. Therefore, the potential on the surface of the insulating layer has characteristics as shown by VM and VBL in FIG. 3 without much difference. The potential of the surface of the insulating layer in the portion corresponding to the cyan portion of the original has a characteristic that is located between Vw, VM, and BL, as shown in c in FIG. After that, the green filter 19 is removed and the red filter 10 is attached to the photoreceptor A.
A multicolor original 2 is given a second color separation image exposure through
In the white part of the photoconductive layer A2, the state of the photoconductive layer A2 does not change much, so the positive charge on the surface of the insulating layer A3 does not attenuate much, and the surface potential is kept fairly constant. It takes the characteristics shown in .

However, in the magenta area of multicolor original 2, the photoconductive layer A2 exhibited high resistance because it was not irradiated with light in the process shown in FIG. It becomes conductive. Therefore, in the process shown in FIG. 2, most of the negative H charges trapped therein are discharged to the conductive support 1, and are only captured by the field of positive charges on the surface of the insulating layer A3. Therefore, in the process shown in FIG. 2, the positive charges on the surface of the insulating layer A3 which were acting quite strongly in the direction of the negative charges captured in the photoconductive layer A2, that is, the initial charge polarity shown in FIG. A field with charges of the same polarity will act as an external field,
The surface potential of the insulating layer A3 increases rapidly with the exposure amount (illuminance×exposure time) of the secondary color separation image exposure through the red filter 10, and reaches a constant surface potential. V in Figure 3
The characteristics are as shown in ML. In addition, the surface potential of the insulating layer A3 corresponding to the black portion of the multicolor original 5 is such that in the secondary color separation image fog light passed through the red filter 10, the reflected light from the multicolor original 2 is small. . However, since there are many positive (4) charges on the surface of the insulating layer 3, the exposure amount also increases rapidly with the exposure amount of the secondary color separation image exposure, but this ratio is smaller than that in the magenta portion of the multicolor original 2. This characteristic is the third
Figure VBL. Shown in D. In addition, this surface potential gradually increases with the passage of time even if it is left in the dark after the secondary color separation image exposure.

This is because the negative (c) charges captured in the photoconductive layer 2 are induced in the conductive support layer a1 at a speed determined by the time constant Rc, which is the product of the resistance R and the capacitance of the photoreceptor A. This is because it combines with positive (a) charges and disappears. Furthermore, the surface potential of the insulating layer A3 corresponding to the cyan part of the multicolor original 2 is such that during the secondary color separation image exposure via the red filter 10, the reflected light from the multicolor original 2 is reflected from the black part. Similarly, the positive (4) charge on the surface of the insulating layer A3 increases with the exposure amount of the secondary color separation image exposure because there is a positive (4) charge on the surface of the insulating layer A3. Since the area is smaller than the area corresponding to the black area, the rate of increase in surface potential is extremely small. This characteristic is expressed as Vc in FIG. Shown in D. Further, even if the document is left in the dark after the secondary color separation image exposure, this surface potential gradually increases with the passage of time, similar to the portion corresponding to the black portion of the multicolor document 2.

Again, this ratio is smaller than the portion corresponding to the black portion. The above VM. L. VBL. D, and Vc. As shown in Fig. 2, the characteristics of 101 on the body
Various changes can be made by exposing the entire surface of the photoreceptor to light of xsec or less.

When the surface of the photoreceptor having the electrostatic latent image formed as described above is developed with magenta toner at an elapsed time that provides the most favorable color correction effect after the secondary color separation image exposure, the multicolor original 5 is A large amount of toner adheres to the portion corresponding to the magenta portion, but less toner adheres to the portion corresponding to the black portion.

Further, there is almost no toner adhesion to the portion corresponding to the cyan portion. Of course, there is no toner attached to the areas corresponding to the white areas. That is, a color corrected magenta toner image is obtained. In the above explanation, the process of color correction of a magenta toner image has been described, but the same process can be performed by variously changing the filter 1 for the primary color separation image exposure and the filter 1 for the secondary color separation image exposure. Color correction of desired color toner images is possible.

In addition, the amount of color correction in each color correction process is very small after the first color separation image exposure on the photoreceptor, before and after the second color separation image exposure, or at the same time as the second color separation image exposure. It is possible to control the amount appropriately by giving a sufficient amount of overall exposure. FIG. 4 shows a specific example of an apparatus for implementing the present invention.

An original 2 placed on the glass of an original table 1 is illuminated by an exposure source 3. The light reflected from the original 2 passes through mirrors 4, 5,
After passing through the lens 6 and mirror 7 and being reflected by the mirror 8, the split light passes through the first color separation filter 1, which is switched according to each color separation, and the color separation filter 1 provided in the turret 9, and then undergoes AC corona removal. The photosensitive drum 11 passes through the electric device 14
exposed to light. The exposure sources 3 and mirrors 4 and 5 in the optical system are 3', 4', and 5, respectively, in synchronization with the rotation of the photosensitive drum 11.
Move to position 5'. The photosensitive drum 11 is purified by a cleaning blade 28, uniformly illuminated by a pre-exposure source 12, charged by a primary charger 13, and charged by an AC corona charge remover 14 simultaneously with exposure. . The exposed photosensitive drum is reflected by a mirror 8 and then divided into parts, and the light passes through an exposure slit 15 through a second color separation filter 1 and a color separation filter 1 provided in a turret 10, which are switched according to each separated color. exposed again. Thereafter, the entire surface is selectively exposed according to each separated color by the entire surface exposure source 16. In addition, this entire surface exposure source 16
The amount of light is adjusted according to each separated color.

Next, the exposed photosensitive drum is transferred to developing devices 17, 18, 19.
Developed by one of the following. The developing device is a color separation filter 9 set in a turret 9.
It operates in synchronization with a, 9b, and 9c. The developed photosensitive drum is charged by a pre-transfer charger 20. On the other hand, the transfer paper 21 is sent out by a delivery roller 22, and is sent out by a delivery guide 23 and a delivery roller 24.
It is held on the transfer drum 25 through the. The image developed on the photosensitive drum is transferred onto transfer paper at the contact point with the transfer drum.

After repeating the same process three times, the transfer paper is separated from the transfer drum, conveyed to a fixing device 27 by a conveyor belt 26, and fixed thereon to complete the copy. The photoconductive layer of the three-layer photosensitive plate used in the present invention preferably has a high resistance value in a dark place.

This is because the dark resistance of the photoconductive layer is high, so that the negative charges trapped in the areas that were not irradiated with the light image during the primary and secondary image exposures are transferred to the conductive layer. Since the possibility of combining with the induced old → charge and disappearing is reduced, a sufficient potential for development is maintained. Considering these points, preferred examples are photoconductive layers of a CdS resin dispersion system, a ZnO resin dispersion system, and a Se-Te vapor deposited layer used in a normal NP process. Table 1 lists filters for primary color separation image exposure, filters for secondary color separation image exposure, and their corresponding color toner color combinations that are effective for the purpose of the present invention.

Further, instead of this filter 1, a light source having spectral characteristics corresponding to the color of the filter 1 can be used for illuminating the original instead of a white light source. In addition, the color of the above-mentioned filter is determined based on the dominant wavelength, color purity, and
It is preferable to select the optimum one in consideration of various characteristics such as brightness and shape of spectral transmission characteristics.

Of course, any known developing method such as a magnetic brush developing method, a sleeve developing method, a cascade developing method, a liquid developing method, etc. can be used to develop the electrostatic latent image formed by the method of the present invention. . The scope of application of the present invention is an electrophotographic photograph having the basic structure of an insulating layer, a photoconductive layer, and a conductive layer, including a primary charging process and a secondary charging process of opposite polarity, to which experts can easily apply the present invention. It goes without saying that the known electrophotographic method using a photoreceptor is included. In order to further facilitate understanding of the present invention, examples will be given and explained below.

Example 1 Tokuko Sho 42-23910 (Canon N
A photosensitive plate having a three-layer structure as described in P process) was prepared.

Microcrystalline CdS (activated by copper) Vinyl chloride monovinyl acetate copolymer 107 Methyl ethyl ketone 207 Methyl isobutyl ketone 30y was uniformly dispersed in the photosensitive solution, and the photosensitive solution was placed on aluminum foil so that the film thickness after drying was 40μ. Apply and dry.

A polyester film having a thickness of 25 .mu.m was adhered thereon using an epoxy resin adhesive to obtain a three-layered photosensitive plate. This was pasted onto the surface of a metal drum using double-sided adhesive tape to create a photosensitive drum.

This photosensitive drum was mounted on the electrophotographic apparatus shown in FIG. 4, and while rotating, the following color correction process of the present invention was carried out.
1 First, create a multicolor original (KOdakCOlOrCOntrOl)
The following steps were performed to form a color-corrected electrostatic latent image of the blue light absorbing portion of Patches (trade name).

The surface of the insulating layer of the photosensitive drum 11 is charged by the primary charger 13.
A 6.2KV corona discharge is performed to uniformly charge the original, and then the multicolor original (KOdakCOlOrCO
ntrOlPatches (product name) 2 is illuminated with an exposure source (2 500W halogen lamps) 3, and the reflected light is transmitted to mirrors 4, 5 and lens 6 (aperture F8,
O) and an optical system of mirror 7, and is reflected by final mirror 8 to project an optical image.

This projection optical path is divided into two parts, and one is passed through the blue filter of the first filter and the turret 9.
While applying primary color separation image exposure to the photosensitive drum 11 through the en-glare 47), at the same time an AC corona discharge of 6.0 K or higher is performed by the AC corona static eliminator 14, and then the other of the two-divided optical path is 2 filters and turrets 10 green filters (KOdakWratt)
en/F658) and an ND for exposure adjustment superimposed on it
Filter one (KOdak Wratten/F696D:
1.0) through the exposure slit 15 to the photosensitive drum 1.
1, a second color separation image exposure was performed. Next, 2.5 seconds after the secondary color separation image exposure, the surface potentials of the portions of the photosensitive drum 11 corresponding to the respective colors of the multicolor original 2 were measured, and the results are shown in the upper row of Table 2. In addition, in order to compare the color correction process with the conventional process, and to clarify the effect of the process, a process of providing full-face exposure using the full-face exposure source 16 instead of the secondary color separation image exposure in the above process. I went to Here, the entire surface exposure source 16 is composed of four 0.5W tungsten miniature lamps, and the amount of exposure is controlled by controlling the power supply voltage. Further, a diffusion plate is provided between the entire surface exposure light source 16 and the photosensitive drum.

At this time, the total exposure amount on the photosensitive drum 11 was 51x. s
It was ec. The surface potentials of the parts of the photosensitive drum corresponding to each color of the multicolor original 2 that have been fully exposed by the full-surface exposure source 16 are as shown in the middle row of Table 2, and therefore the difference in surface potential between the two processes is as follows. It will look like the bottom row of Table 2. Next, the following steps were performed to form a color-corrected electrostatic latent image of the green light absorbing portion of the multicolor original 2.

Similar process to 1, except that the 1st color separation image exposure
Grid 2 of the filter 1/turret 9 and the ND filter 1 (Wr-Atten 58) superimposed thereon for adjusting the exposure amount.
96D:0.4).

In addition, in the secondary color separation image exposure, the red filter 3 (Wrat
The light was passed through an ND filter (Wratten 96D: 1.6) superimposed on it for adjusting the exposure amount. After 2.5 seconds of secondary color separation image exposure, the surface potential of the electrostatic latent image on the photosensitive drum 11 corresponding to each color of the multicolor original 2 is measured, and this is compared to the conventional method shown in the upper part of Table 3. For comparison with the process, instead of the secondary color separation image exposure in the color correction process described above, a 51x. se
The middle row of Table 3 shows the surface potential of the multicolor original 2 when the entire surface exposure amount of c was given. Therefore, the potential difference between the two is as shown in the lower part of Table 3. The color-corrected electrostatic latent image of the blue light-absorbing portion of the multicolor original 2 formed on the photosensitive drum by carrying out step 1 above is exposed to yellow toner after 15 seconds of secondary color separation image exposure. Included magnetic brush developer 1
7, and then, in order to improve the transferability on the developed yellow toner image, a -5.8 KV corona discharge was applied to the pre-transfer charger 20 to uniformly charge the yellow toner image. A yellow toner image was transferred onto a transfer paper wrapped around a transfer roller 25 having a grounded conductive rubber surface. Next, the toner remaining on the photosensitive drum 11 without being transferred is cleaned with a cleaning blade 28, and then the pre-exposure source 12 uniformly applies pre-exposure to the photosensitive drum 11, and then the step 2 is performed. After 2.5 seconds of secondary color separation image exposure, the color-corrected electrostatic latent image of the green light-absorbing portion of the multicolor original 2 formed on the photosensitive drum 11 is transferred to a magnetic brush containing magenta toner. The image was developed by the developing device 18, and the magenta toner image was aligned and superimposed on the transfer paper onto which the yellow toner image had been transferred in the same process as described above. Next, the electrostatic latent image of the red light-absorbing portion of multicolor original 2 is created in a process similar to 1, except that
In the next color separation image exposure, the red filter 1 (Wratten 25) of the first filter 1/turret 9 and the ND filter 1 (Wratten/
16.96D: 0.9), and instead of the secondary color separation image exposure, a 51x. It was formed on the photosensitive drum 11 by applying a total exposure amount of sec.

This electrostatic latent image is developed by a magnetic brush developer 19 containing cyan toner, and this cyan toner image is transferred onto a transfer paper onto which a yellow toner image and a magenta toner image have been transferred in the same process as described above. The images were aligned and transferred one over the other.

Next, this transfer paper is separated by a separating claw 28 and transferred to a heat fixing device 2.
It took root in 7.

The obtained multicolor copy image exhibited extremely faithful color reproduction to the multicolor original 2, and the green, red and violet images were especially vivid.

Furthermore, magenta, evening, and cyan images were formed using only magenta and cyan toners, respectively. The black image had a color close to pure black. Furthermore, the image had high sharpness with no blurring of fine lines such as letters. Example 2 An image was formed on the transfer drum 25 by a process similar to Example 1.
The yellow, magenta and cyan toner images are transferred to the upper transfer paper, and the full exposure source 16 of the electrophotographic device shown in FIG. followed by 0.21x, . sec overall exposure, followed by a second color separation image exposure through a red filter, followed by a 0.11x. This process differs from the previous process in that a total exposure amount of sec is applied to the photosensitive drum 11 in each image forming process.

Furthermore, a black toner image formed on a photoreceptor was transferred in a superimposed manner on top of the three-color toner image on the transfer paper in the following steps.

This process is similar to the process of Example 1, but instead of the primary color separation image exposure, an ND filter for adjusting the exposure amount of the first filter and turret 9 (Wratten 96D:1
．． 0), and in place of the secondary color separation image exposure, the entire surface exposure source 16 provides 51x-Se image exposure.
An electrostatic latent image corresponding to the brightness and darkness of the multicolor original 2 is formed on the photosensitive drum 11 by exposing the entire surface of the document 2, and this is developed using a magnetic brush developer (not shown) containing black toner. did. Next, the transfer paper on which the four color toner images were superimposed was separated and passed through a thermal fixing device 27 to be fixed.

In the obtained multicolor copy image, compared to that obtained in Example 1, the image density increased in the part corresponding to the black part of the multicolor original 2, becoming pure black, and the clarity was increased; The effect of color correction on the parts corresponding to colors other than the black parts of color original 2 was almost unchanged. Example 3 Pellets of Se and Te (weight ratio 90:10) were placed in a crucible and heated in a vacuum at about 450°C in an electric furnace to melt them, and the pellets were placed in an aluminum drum to a thickness of 40 μm. A 25 μm thick polyester film was then bonded thereon with an epoxy resin adhesive to create a three-layered photosensitive drum.

This photosensitive drum was installed in the electrophotographic apparatus shown in FIG. 4, and the same steps as in Example 1 were carried out to copy a multicolor original. However, the polarity of the charging was reversed, and instead of AC corona static elimination, the polarity of charging was opposite to that of the primary charging. On the other hand, color toners with positive charges were used. Furthermore, the aperture of the lens was set to F5.6. The multicolor copy image obtained by carrying out the same steps as in Example 1 in all other respects showed an extremely faithful reproduction of the multicolor original 2. As described above in detail, the method of the present invention makes it possible to form an image with good color correction through a simple process.

Moreover, it is also effective in that reproduction color correction can be controlled extremely easily.

[Brief explanation of drawings]

FIG. 1 explains typical spectral reflection characteristics of coloring materials in practical use. FIGS. 1-5 illustrate the electrostatic latent image forming process according to the present invention. FIG. 3 explains potential changes on the surface of the photoreceptor in each step of forming an electrostatic latent image. Fourth
The figure is for explaining the outline of an apparatus for carrying out the present invention.
In the figure, A...Photosensitive plate, A...Conductive layer, A2...Photoconductive layer, A3...Insulating layer, 1... ... Document table, 2 ... Original original, 3 ... Illumination light source, 11 ... Photoreceptor drum.

Claims (1)

[Claims] 1 Using a photoreceptor having an insulating layer, a photoconductive layer, and a conductive layer,
irradiating the surface of the photoreceptor charged with a predetermined polarity with a multicolor original light image via a desired developing complementary color filter;
a step of reducing the charged charge of the predetermined polarity at the same time as or before and after the irradiation of the light image, applying the multicolor to the surface of the photoreceptor through a filter that transmits the light image of the portion to be developed with the development color of the multicolor original; An electrophotographic method comprising the step of irradiating an original light image and forming an electrostatic latent image according to a desired developed color.