JPS6325663B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method using light-transmitting particles, and particularly to improvements in an electrophotographic photosensitive plate used in the method.

The present inventors previously proposed a novel image forming method using light-transmitting particles. The image forming principle is to electrostatically attach optically transparent particles, that is, light-transmitting particles, which are image forming members, to the entire surface of a photoreceptor using a photoconductor as a photosensitive member, and then the particles The surface is exposed imagewise, and the light that passes through the particles attenuates the resistance of the photoreceptor according to the light image, creating a difference in the electrostatic attraction between the particles and the photoreceptor in the exposed and non-exposed areas. Form a latent image. Next, the particles in the exposed area and the particles in the non-exposed area are physically selectively separated using the difference in their electrostatic attraction and developed to obtain a particle image.

In the above-mentioned image forming method, when a light image is directly irradiated onto the photoreceptor, which is exposed in the gaps between the light-transmitting particles during conventional image exposure, a portion of the light diffusely reflected on the surface of the photoreceptor is transmitted to the unexposed area. There was a problem in that the light was reflected by the particles and exposed the photoreceptor in the unexposed area, reducing the difference in electrostatic attraction between the exposed area and the unexposed area, making the developing conditions stricter. This phenomenon is particularly noticeable in the three colors of red, green, and blue-violet light.
When a color image is reproduced by one-time exposure and one-time development using various kinds of light-transmitting particles, the color reproduction characteristics are greatly affected. Therefore, it has been difficult to obtain clear color images with excellent color reproduction characteristics using a photoreceptor using a white photoconductor such as zinc oxide or titanium oxide, which has large diffused reflection.

An object of the present invention is to provide an electrophotographic photosensitive plate that overcomes these conventional drawbacks. Specifically, it is an object of the present invention to provide an electrophotographic photosensitive plate that can reduce the influence of diffused reflection and provide clearer images.

In the present invention, when light-transmitting particles are electrostatically adhered to a photoreceptor, the gaps between the particles, that is, the portion directly exposed to the light image, are made of a black conductor, thereby preventing diffused reflection on the surface of the photoreceptor. An object of the present invention is to provide an electrophotographic photosensitive plate that reduces the influence of. In other words, an electrophotographic photosensitive plate that can be applied to the image forming method described above does not necessarily have a photoreceptor provided entirely on a conductive substrate, such as selenium or zinc oxide electrophotographic plates used in conventional xerography or electrofaxing. There's no need to be. In other words, in principle, it is sufficient to have a photoreceptor only in the part that comes into contact with the light-transmitting particles; therefore, the photoreceptor in the part that does not come into contact with the light-transparent particles is not only unnecessary for image formation, but also as described above. This causes the image quality to deteriorate due to the influence of diffused reflection.

In view of the above, the present invention has a structure in which a photoreceptor including a photoconductor is finely divided by black conductors, thereby preventing diffuse reflection of light in areas unnecessary for image formation, and in which light-transmitting particles are added to the parts. It is designed to prevent electrostatic adhesion.

Photoconductors used in the present invention include those commonly used in electrophotography, such as zinc oxide, titanium oxide, cadmium sulfide, selenium, selenium-tellurium alloy, poly-N-vinylcarbazole, and poly-N-vinylanthracene. All applicable photoconductors are applicable.

Examples of the black conductor used in the present invention include metal powders such as nickel, iron, platinum black, chromium, and cobalt, metal oxides such as manganese dioxide and lead oxide, and tetracyanoquinodimethane (TCNQ). and tetrathiofulvalene (TTF), organic charge transfer complexes such as TCNQ and tetracene, carbon, and polymer electrolytes such as polymeric quaternary ammonium salts, which are made black by dispersing dyes or pigments, or the above-mentioned A polymer electrolyte in which an inorganic black substance such as cupric oxide or iron oxide is dispersed is used. These black conductors are used by being dispersed in a resin binder if necessary, but in any case, it is preferable that the surface resistivity of the single substance or composite is 10 ⁹ Ω or less and that there is no electrostatic charge.

Next, embodiments of the present invention will be described based on the drawings.

In FIG. 1, 1 is an aluminum plate, for example.
A conductive substrate such as metallized paper or paper impregnated with a polymer electrolyte, on which the photoconductor 2 described above is placed.
are provided by conventional means. A conductive ink 4 in which the aforementioned black conductor is dispersed in molecules or particles in a binder is applied to the surface of the photoreceptor 3 using a normal printing technique, for example, as shown in FIGS. 2A and 2B. The non-printing area is formed by printing so that it becomes a circle.

Another embodiment according to the invention is shown in FIG. For example, on a black conductive support 5 such as paper coated with black conductive ink or a metal plate dyed black by ordinary means as explained in FIG. This is an example in which the photoconductive ink 6 obtained by particle dispersion is finely divided into square or circular dots and printed by gravure printing or screen printing so that the ink film thickness is 10 to 50 μm.

Another embodiment according to the invention is shown in FIGS. 4 and 5.
Conductive particles 7 and photoconductive particles 8 obtained by granulating the above-described black conductive ink and photoconductive ink by, for example, a spray drying method are attached to a conductive support 1.
It can be obtained by compression bonding or heat-sealing on top.

The photosensitive plate shown in Figure 6 contains zinc, magnesium,
The banks 10 of the conductive support 9 are etched with the pattern shown in FIG. 2 to a groove depth of 10 to 50 μm using ordinary photoetching techniques on a metal plate such as copper, and then the banks 10 of the conductive support 9 are dyed black, and a photoconductor is placed in the grooves. This is obtained by embedding .

In the electrophotographic photosensitive plate of the present invention as described above, the size of the photoreceptor containing the finely divided photoconductor is preferably 1 to 100 μm in diameter. Further, the sizes of the photoreceptors do not necessarily have to be the same. The surface area ratio of the finely divided photoreceptor varies depending on the shape and refractive index of the light-transmitting particles used for image formation. For example, assume that the light-transmitting particles are spherical and have a refractive index of 1.5. When these particles are electrostatically deposited in a line on a conventional electrophotographic photosensitive plate, the filling rate is about 75%, and the area directly irradiated with a light image is about 25%.
Therefore, it is sufficient for the surface area ratio of the photoreceptor to be about 75%. However, when a light image is irradiated onto a light-transmitting particle, the light is refracted, so that only 25% of the projected area of the particle is irradiated onto the photosensitive plate. Therefore, the surface area ratio of the photoreceptor necessary for image formation should be at least about 18%. Therefore, the surface area ratio of the photoreceptor varies depending on the shape and refractive index of the light-transmitting particles, but is preferably 15% to 75%.

Next, specific examples will be described.

First, the following formulation was thoroughly mixed in a ball mill and coated on aluminum vapor-deposited paper to a thickness of about 20 μm.

Zinc oxide SAZEX-2000 (manufactured by Sakai Chemical Industry Co., Ltd.)
100 parts by weight Binder Acridix 6-1036 (Nippon Reich Co., Ltd.)
20 parts by weight Sensitizer Tartrazine 0.5 〃 Rose Bengal 0.01 〃 Patent Pure Blue 0.02 〃 Toluene 100 〃 Next, the following formulation liquid was sufficiently dispersed and mixed in a ball mill to prepare a conductive ink.

Conductive carbon powder 100 parts by weight Alkyd resin 15 〃 Toluene 50 〃 Next, use normal plate making technology so that the non-image area (the part where ink does not adhere) is a circle with a diameter of 50μ and the distance between the centers of the circles is 70μ. The resulting PS plate was used as a printing plate and printed on the previously prepared zinc oxide paper using the above conductive ink to obtain an electrophotographic photosensitive plate as shown in FIG. 2B. The surface resistivity of the conductive ink adhesion surface is approximately 10 ⁸
It was Ω.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the photosensitive plate of the present invention, FIG. 2 is a plan view thereof, FIGS. 3 and 4 are longitudinal sectional views showing other embodiments, and FIG. 5 is a conductive FIG. 6 is a longitudinal cross-sectional view of another embodiment. 1... Conductive substrate, 2, 6, 8, 11... Photoconductor, 4, 5, 7, 10... Black conductor.

Claims (1)

[Scope of Claims] 1 Electrophotography in which light-transmitting particles are electrostatically adhered to the surface of a photoreceptor, imagewise exposed from the particle surface, and then developed to form a particle image made of the particles on the photoreceptor. 1. An electrophotographic method, characterized in that the photoreceptor is finely divided by a black conductor. 2. The electrophotographic method according to claim 1, wherein the finely divided photoreceptor has a diameter of 1 to 100 μm. 3 The surface area ratio of the finely divided photoreceptor is 15~
75%. 4. The electrophotographic method according to claim 1, wherein the black conductor has a surface resistivity of 10 ⁹ Ω or less.