JPS6048032B2 - Image forming method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method and apparatus using light-transmitting particles.

Specifically, the present invention relates to an image forming method and apparatus that can easily produce images with improved S/N. Conventionally, as typical image forming methods using fine particles, an electronic scribing method using photoconductive particles as the particles, a Shugerman method, and the like have been proposed.

However, in both methods, charged particles and uncharged particles are selectively distinguished by physical means or electrical means depending on the charged state of photoconductive particles dispersed on a conductive support. This method was used to obtain particle images separately. In other words, it is an image forming method that converts a J-light image into a particle image by utilizing the photoconductive function of the particles themselves. In the Shugerman method, it was removed from the conductive support by a jet or by an electric field.

It is therefore necessary that the photoconductive particles are arranged as closely as possible in a layer on the conductive support, and that the particles are in ohmic contact with the conductive support. Furthermore, it is necessary that the electrostatic properties of the individual particles be the same.
However, it is technically very difficult to satisfy the above-mentioned requirements, and even if it were technically possible, if this was made into a device, the device would be complicated and large, and the cost would be high. It was hot. Therefore, the present inventors previously proposed a novel method for obtaining images by electrophotography using light-transmitting particles. The principle of the image forming method is, at least, that light-transmitting particles are electrostatically attached to the surface of a support containing a photoconductive substance, and after image exposure, the electrostatic attraction with the support is weakened or removed. This is a method in which the particles are removed from the support to obtain an image of the remaining particles, and this is transferred or fixed by an appropriate means. in this case,
Due to image exposure, the difference in electrostatic attraction between particles irradiated with light and particles that were not irradiated, that is, the S/N was not sufficient. In particular, when reproducing full-color images, three types of light-transmitting particles are used that transmit red, green, and blue light and have corresponding cyan, magenta, and yellow coloring materials.
There was a drawback that a sufficient S/N ratio could not be obtained. Therefore,
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method and apparatus that improve the above-mentioned conventional drawbacks. Another object of the present invention is to provide an optimal image forming method and apparatus for obtaining clear color images with excellent color reproduction and little fogging. Hereinafter, the principle of the present invention will be explained based on the drawings. Note that these drawings are shown as models for ease of explanation. Therefore, the size! There are some parts that do not match reality, such as the method and particle filling rate. first,
As shown in FIG. 1, the conductive substrate 1 has at least
A photoconductive support 3 provided with a photosensitive layer 2 containing a type of photoconductive substance is negatively charged, for example by means of a corona charger 4, in a dark place.

Of course, if the photoconductive substance is a p-type semiconductor, it will be positively charged. Next, as shown in FIG. 2, light-transmitting particles 6 are scattered onto the surface of the charged photoconductive support 3 using a particle scatterer 5, and the particles 6 are electrostatically adhered to the support 3. . At this time, it is desirable that the particles 6 are arranged in almost a single layer. Next, a step of removing charges other than the projected area of the particles 6 is performed.

FIG. 3a shows the method by electrical means. As shown in the figure, a photoconductive support 6 sprinkled with particles 6 is placed in a corona charger 4.
The entire surface becomes positively charged. Then, the projected area of the particle 6 will not be charged, and the area other than the projected area of the particle 6 will be charged.
The negative charge that had been charged is neutralized by the applied positive charge, giving a further positive charge, but since the photoconductive support is an N-type semiconductor, it is difficult to retain the positive charge. be. Therefore, the electric charge on the projected portion of the particle 6 does not change, and the electric charge on the portion other than the projected area is neutralized, and the potential becomes approximately the reference potential. In this case, the photoconductive support 3
The effects of the present invention can be enhanced by modifying the photosensitive layer 2 so that it is not positively charged by ordinary means. FIG. 3b also shows a method using optical means.

As shown in the figure, this can be achieved by irradiating the entire surface of the light source 7 with light in a range that does not transmit the particles 6 but can sensitize the photoconductive support 3. For example, when zinc oxide is used as the photoconductive material and the particles are dyed in red, green, and blue, respectively, the above conditions apply to ultraviolet light, which has sensitivity specific to zinc oxide. The particles 6 from which charges other than the projected area have been removed in this way are exposed to image light through the original 8 as shown in FIG. 4, and the charges on the support 3 corresponding to the exposed areas are optically attenuated. Next, as shown in FIG. 5, the support 3 is vibrated by, for example, an electromagnetic vibrator 9, and the support 3 is irradiated with light.
When the particles 6'' whose electrostatic attraction has been weakened or removed are removed, only the particles 6'' on which the electrostatic attraction is strongly acting remain on the support 3, and a positive particle image is formed with respect to the original 8. can get. Next, an image is formed by transferring or fixing by appropriate means. As the light-transmitting particles used in the present invention, natural and synthetic resins with excellent transparency can be used.

Examples include styrene resin, acrylic resin, methacrylic resin, polyester resin, nitrocellulose, ethylcellulose, acetylcellulose, epoxy resin, melamine resin, area resin, starch, polyvinyl alcohol, gelatin, and rosin. Furthermore, inorganic materials such as glass, ceramic, and silica gel can be used. A normal granulation method can be applied to manufacture the light-transmitting particles.

Examples include rolling granulation method, spacing granulation method, spray drying method, fluid coating method, interfacial polymerization method, and submerged curing coating method.
Moreover, it is preferable that the light-transmitting particles are electrically conductive. If the particles are electrically conductive, the filling rate of the particles will be improved when the particles are dispersed on a photoconductive support, and fog during development will be reduced. As the conductive material for imparting conductivity, a light-transmitting material is preferable. However, opaque materials can also be used. For example, metal compounds such as copper iodide, tin oxide, and indium oxide, metals, polymer electrolytes such as polymer quaternary ammonium salts, carbon, and the like can be used. These conductive materials are made conductive by dispersing molecules or particles in particles. Alternatively, the surface of the particles can be treated by applying the granulation method described above. Furthermore, vapor deposition methods, plating methods, etc. can also be applied. The particle size of the particles obtained by the above method is suitably 1 to 100 microns. Further, the shape is preferably approximately spherical.
At least three types of light-transmitting particles are used to form a color image.

Specifically, a coloring material is used that transmits at least one color selected from the three primary colors of the additive coloring method and develops one color selected from the three primary colors of the subtractive coloring method, which is a complementary color of the color. That is, it is shown that the red particles contain a coloring material that transmits red light and develops cyan. Similarly, green particles and blue particles transmit green and blue light, respectively, and magenta,
Contains a colorant that develops yellow. These spectral functions can be imparted to particles by appropriately combining dyes and pigments. Further, as the coloring material, colorless and colored sublimable dyes are suitable. In addition, examples of the support containing a photoconductive substance used in the present invention include photoconductive substances such as selenium, zinc oxide, cadmium sulfide, titanium oxide, poly-N-vinylcarbazole, and poly-N-vinylanthracene. The substance is deposited or coated on a conductive substrate such as a metal plate, metallized paper, metallized film, or paper coated with a low resistance agent such as a quaternary ammonium salt.

The photoconductive material may be dye-sensitized or chemically sensitized, if necessary. Next, FIG. 6 shows an embodiment of an image forming apparatus for producing hard copies according to the present invention.

A photoconductive endless belt 11 mounted in a housing 10 and made of, for example, an aluminum plate coated with particles of zinc oxide as a binder, is driven by drive rollers 13 and 14 via a drive motor 12. driven. The belt 11 is first negatively charged by a first corona charger 15 . Next, the light-transmitting particles 17 are spread onto the charged belt 11 by the particle spreader 16, and the particles 17 are arranged in approximately one layer by the doctor 18. Further, excess particles are collected in the particle container 19. Next, the process moves to the step of removing charges other than the projected area of the particles. For example, by electrical means, the particle is positively charged by the second corona charger 20, and charges other than the projected area of the particle are neutralized to a reference potential.
In the case of using optical means, a light source that emits a Shiba ray is provided. Next, when the belt 11 is driven to the exposure section, the driving of the belt 11 is temporarily stopped, and the optical image of the document 22 placed on the glass plate 21 is irradiated onto the particles 17 . Here, 23 represents a light source, and 24 represents a lens system. Next, after the image exposure is completed, the belt 11 is driven again, and the belt 11 is vibrated by the electromagnetic vibrator 25 provided in contact with the belt 11. Then, the electrostatic attraction of the particles corresponding to the exposed area on the belt 11 is weakened or removed, so they are shaken off and collected in the particle receiver 26, and there are particles on the belt 11 that are positive with respect to the original 22. A particle image is obtained. Next, the particle image formed on the belt 11 is
For example, the image is transferred and fixed onto the image receiving medium 28 by a heating and pressing roller 27, and then cut by a cutter 29 to obtain a copy. After the particles have been transferred, the belt 11 is then moved to a cleaning brush 3 to remove some remaining particles.
After cleaning with 0, it is used again. As described above, in the image forming method of the present invention, at least light-transmitting particles are electrostatically attached to the surface of a support containing a photoconductive substance, and charges other than the projected area and area of the particles are removed. The method is characterized in that it includes a step of removing particles whose electrostatic attraction with the support has been weakened or removed after imagewise exposure from the support. In the present invention, by removing charges other than the projected area of the light-transmitting particles, the difference in electrostatic attraction between the exposed particles and the unexposed particles, that is, the S/N, can be reduced when imagewise exposed. It is something that can be improved. In other words, charges other than the projected area of the light-transmitting particles act as a noise component from the perspective of the image forming process, and are a major factor that hinders improvement in image quality. Therefore, the present invention makes it possible to obtain clear images with less fog. Examples of the present invention will be described below. Example 1 A panchromatic zinc oxide photosensitive plate obtained by a conventional manufacturing method was charged with a corona charger applying -6 KV in a dark place.
Glass beads coated with tin oxide and having an average particle diameter of 40 microns and a specific resistance of 103 Ω·o were placed on a photosensitive paper, and then charged with a corona charger applying +5 KV.

Next, after exposing the black and white transparent original with an incandescent light bulb, the fifth
When the particles were developed using the developing device illustrated in the figure, it was easier to develop and a clearer particle image was obtained compared to a device that does not remove charges other than the projected area of the particles. Example 2 200 g of each of red (RATUTEN NO. 25), green (RATUTEN NO. 58), and blue (RATUTEN NO. 47B) aqueous gelatin solutions used in gelatin filters for color separation were prepared.

When 3 g of formalin was added to each of these three types of aqueous gelatin solutions and granulated using a spray dryer, particles dyed in red, green, and blue were obtained. Next, 100 g of red particles were mixed and dispersed with 0.5 g of cyan sublimable dye Kayaset Blue FR (manufactured by Nippon Kayaku Co., Ltd.) and 100 g of 0.05% nitrocellulose thinner solution, and green particles were mixed and dispersed. Magenta sublimable dye Mitsui PS Red G (
Mitsui PS Yellow GG (manufactured by Mitsui Toatsu Chemical Co., Ltd.) is mixed and dispersed with 100 g of 0.05% nitrocellulose thinner solution, and 100 g of blue particles are mixed with yellow sublimable dye Mitsui PS Yellow GG (Mitsui Toatsu Chemical Co., Ltd.). Co., Ltd.) 0.3g
and 100g of 0.03% thinner solution of nitrocellulose
The mixed and dispersed particles were each spray-dried and thoroughly mixed to obtain light-transmitting particles for full color. Next, a panchromatic zinc oxide photosensitive plate obtained by a conventional manufacturing method was charged in a dark place using a corona charger applying a voltage of -6 KV, and the particles were scattered thereon.

Apply an interference filter to the mercury lamp and the peak wavelength will be 380r1m.
After exposing the entire surface to light, the color original was exposed to light using an incandescent light bulb, and the resulting particle image was electrostatically transferred onto plain paper by developing it with the developing machine explained in Figure 5 and heating it to 1700C. When heated for 10 seconds using a heated hot plate, a positive color copy was obtained.

[Brief explanation of the drawing]

1 to 5 are diagrams showing the principle of the image forming method of the present invention, and FIG. 6 is a schematic diagram showing an example of the image forming apparatus of the present invention.

Claims (1)

[Claims] 1. A step of electrostatically attaching light-transmitting particles to the surface of a support containing at least a photoconductive substance, a step of removing charges other than the projected area of the particles, and particles on the surface of the support. 1. An image forming method comprising a step of imagewise exposure to light, and a developing step of removing the light-transmitting particles whose electrostatic attraction with the support has been weakened or removed from the support. 2. Claim 1, wherein the step of removing charges other than the projected area of the light-transmitting particles comprises electrically removing charges.
Image forming method described in section. 3. Claim 1, wherein the step of removing charges other than the projected area of the light-transmitting particles comprises optically removing charges.
Image forming method described in section. 4 A device for holding a support containing at least a photoconductive substance, a first charge-imparting device for applying an electric charge to the support, a device for dispersing light-transmitting particles onto the surface of the support, and a first charge-imparting device a second charge applying device that applies a charge of opposite polarity to the support surface having the particles; a device that imagewise exposes the particles on the support; and a device that weakens or eliminates the electrostatic attraction between the support surface and the particles. An image forming apparatus characterized by having a developing device for removing particles in a portion where particles are removed. 5 A device for holding a support containing at least a photoconductive substance, a device for imparting an electric charge to the support, a device for scattering light-transmitting particles on the surface of the support, and a device for removing charges other than the projected area of the particles. An image forming apparatus comprising: a full-surface exposure device; a device that imagewise exposes particles on a support; and a development device that removes particles in areas where the electrostatic attraction between the surface of the support and the particles is weakened or removed.