JPS628170A - Electrophotographing method - Google Patents

Abstract

PURPOSE:To easily obtain a black-erased or decolored copy from an original which has a black part and a color part by applying a necessary voltage between the conductive base body of a photosensitive body and a charge detection plate and irradiating the photosensitive body with light through the charge detection plate. CONSTITUTION:The charge detection plate 2 is brought close to and opposed to the photosensitive body 1 which has charge patterns 11 and 13 and a no-charge area 12 and the voltage is applied from a power source 3 between a transparent electrode 2a of the charge detection plate 2 and the conductive base body 1b of the photosensitive body 1. Then, when light 5 is irradiated from the side of a transparent electrode 2a of the charge detection plate 2, the light 5 reaches the surface of the photosensitive body in an area on the charge detection plate 2 corresponding to the charge pattern 11 because of its high transmissivity, but the light 5 does not reaches the surface of the photosensitive body 1 in an area on the charge detection plate 2 corresponding to the charge pattern 13 and no-charge are 12 because of their low transmissivity. Then when the light 5 is intense enough to make the photosensitive layer 1a of the photosensitive body 1 conductive, charges of the charge pattern 11 are erased and only the charge pattern 13 remains on the surface of the photosensitive body 1.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to electrophotography, and in particular to selectively erasing one of the electrostatic latent images from a photoreceptor having two types of electrostatic latent images with high and low charge densities. For example, in electrophotography, one of the electrostatic latent images is created from a photoreceptor that has an electrostatic latent image corresponding to the black area and an electrostatic latent image corresponding to the color area, which is created based on an original with black areas and colored areas. This invention relates to an electrophotographic method for selectively erasing electrolatent images.

[Background of the invention]

For example, black letters □・
It has black parts like , and colored parts like colored characters.
□゛There are cases where it is desired to erase either the black part or the color part from such a document to obtain a copy of only the black part or a copy of only the color part.

In order to meet the above requirements, a method using a multilayer photoreceptor with filter characteristics is considered, but this method requires complicated gross processing and delicate control, and does not always produce satisfactory results. can't get it. Another possibility is to use a bipolar photoreceptor, but with this method, it is difficult to realize the photoreceptor itself.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic method with a relatively simple process for obtaining a copy from an original having either black or colored parts erased.

[Summary of the invention]

In order to achieve the above object, the present invention provides a photoreceptor having electrostatic latent images of two types of high and low charge densities, consisting of a conductive substrate and a photosensitive layer. A charge detection plate formed by laminating a layer of a material whose transmittance changes to become transparent or non-transparent at a certain value and a transparent electrode is disposed close to each other, and between the conductive base of the photoreceptor and the charge detection plate. It is characterized in that either one of the two types of electrostatic latent images is selectively erased by applying a required voltage and irradiating light onto the photoreceptor through the charge detection plate. .

[Embodiments of the invention]

The present invention is implemented using a photoreceptor carrying charge patterns with different charge densities and a charge detection plate with different transmittance depending on the strength of the electric field. This will be explained according to FIG.

In FIG. 1, 1 is a photoreceptor, a photosensitive layer 1& and a conductive substrate 1b.
On the surface of the photosensitive layer 1 of the photoreceptor 1, a charge AI ethanon 1.13 as an electrostatic latent image and a charge-free region 12 are formed and divided by a known method. Here, the charge no-turn 11 forms a latent image of high charge density formed corresponding to, for example, a black part of the original, and the charge A-turn 13 forms a latent image of low charge density formed corresponding to, for example, a colored part of the original. It is what you do.

In the figure, reference numeral 2 denotes a charge detection plate, which is constructed by laminating a transparent electrode 21, a field effect liquid crystal 2b, and a transparent insulating layer 2c. Further, in the figure, reference numeral 3 denotes a power source for applying a voltage between the conductive base 1b of the photoreceptor 1 and the transparent electrode 2& of the charge detection plate 2.

The charge detection plate 2 is brought close to face the photoconductor 1 having the charge/4 turns 11.13 and the uncharged area 12, and the conductivity of the transparent electrode 2a of the charge detection plate 2 and the photoconductor 1 is determined by the power supply 3. A voltage is applied between the base bodies lb.

The field-effect liquid crystal 2b in the charge detection plate 2 has a high transmittance in a region where the electric field strength acting on it exceeds a threshold value Is, and a low transmittance in a region where the electric field strength does not exceed a threshold value Ha. This is a material layer whose transmittance changes depending on the electric field intensity and has the characteristics shown in FIG. Therefore, in the above-mentioned voltage application state, the area on the charge detection plate 2 corresponding to the high-density charge nof turf 11 has an electric field strength equal to the threshold value E.
m), other charges/
The areas on the charge detection plate 2 corresponding to the pattern 13 and the uncharged area 12 have low transmittance.

Next, light 5 is emitted from the transparent electrode 2a side of the charge detection plate 2.
When the light 5 is irradiated, the light 5 reaches the surface of the photoreceptor 10 due to its high transmittance in the area on the charge detection plate 2 corresponding to the charge/four turns 11, but it corresponds to the charge/four turns 13 and the uncharged area 12. In the areas on the charge detection plate 2 where the photoreceptor 1 is exposed, the light 5 does not reach the surface of the photoreceptor 1 due to its low transmittance. If the light 5 is strong enough to make the photosensitive layer 1a of the photoreceptor 1 conductive, the charge 4 turns 11
The charge is erased, and only the charge/turf 13 remains on the surface of the photoreceptor 1.

An adjustment is made to form a charge pattern 11 with a high charge density and a charge pattern 13 with a low charge density on the photoreceptor 1 corresponding to the black part and the color part of the original, respectively, so as to create a difference in charge density between the two charges and the main turn. This can be done by conventionally known technical means, taking into consideration the spectral characteristics of the photoreceptor 1 and/or the spectral characteristics of the optical system for latent layer formation. By applying the method described above, it is possible to erase only the charge/arm turn 11 corresponding to the black part of the original. .

In the above embodiment, the charge detection plate 2 using the field effect liquid crystal 2b has been described, but the same effect can be achieved by using PLZT, electrochromic material, etc. instead of the field effect liquid crystal 2b.

FIG. 3 shows another embodiment different from the embodiment shown in FIG. No. 4 turn 13 is erased. That is, like the charge detection plate 2, the charge detection plate 6 is composed of a transparent electrode 6, a field effect deafening liquid crystal 6b, and a transparent insulating layer 6c, but its characteristics are limited to the electric field strength below the threshold value Es. By performing a process similar to the example shown in FIG. 1, which shows an increase in transmittance.

It is possible to erase charge/mother turns 13 with a low charge density and leave charge no-turns 11 with a high charge density.

In both of the above two embodiments, the charge level is 4 for a positive latent image.
Although this is an example of selectively erasing turns, it goes without saying that the method of the present invention can also be applied to one-inversion latent images to selectively erase unnecessary charges/f turns.

〔Effect of the invention〕

According to the present invention, one of the latent images can be erased by a simple process from a photoreceptor having latent images of charge/amount turns with different charge densities on the surface. For example, a blackened or achromatic copy can be easily obtained from a document having black and colored parts.

[Brief explanation of the drawing]

1FgJ is an explanatory diagram of one embodiment according to the present invention, FIG. 2 is a characteristic diagram of an example of a charge detection plate used in the present invention, and FIG. 3 is an explanatory diagram of another embodiment according to the present invention. 3...Power supply

Claims (1)

[Claims] A photoreceptor consisting of a conductive substrate and a photosensitive layer has two types of electrostatic latent images with high and low charge densities, and transparent insulating layers, which are transparent or non-transparent at a threshold of electric field intensity, are arranged in order of distance from the photoreceptor. A charge detection plate formed by stacking a layer of material whose transmittance changes and a transparent electrode are arranged in close proximity, and a required voltage is applied between the conductive base of the photoreceptor and the charge detection plate to pass through the charge detection plate. An electrophotographic method characterized in that one of the two types of electrostatic latent images is selectively erased by irradiating the photoreceptor with light.