JPH0213791B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an image forming method that utilizes the image forming function of a photoconductive substance and the color separation function of light-transmitting particles. More specifically, a support including a photoconductive layer is charged, and a plurality of types of light-transmitting particles having a color separation function are electrostatically deposited on the support, a scattering step being performed;
The present invention relates to an improvement in an image forming method in which a particle image is obtained on a support by performing imagewise exposure through the particles and removing particles whose electrostatic adhesion to the support has been weakened or removed. The present invention relates to the image forming method described above, which is characterized by an improved support and a spraying step. Conventional image forming methods in this field use a support that includes a panchromatic photoconductive layer, use mixed particles made by mixing equal amounts of multiple types of light-transmitting particles with different color separation functions, and disperse them randomly. A method (hereinafter referred to as the mixed particle method) has been proposed. Another image forming method in this field uses a support containing a panchromatic photoconductive layer to form a particle group in which a plurality of light-transmitting particles having the same color separation function are aggregated, and adjacent particles A method has also been proposed in which the color separation function of particles forming a group is dispersed as different particle groups (hereinafter referred to as particle group method). However, since both the mixed particle method and the particle swarm method use panchromatic photoconductive materials, the color separation function of the particles has a large effect on image quality, making it difficult to expand the latitude. It was hot. First, in order to clarify the difference from the present invention described later, the above-mentioned problems will be explained based on the drawings. In FIG. 1, particles R that transmit red light and particles G that transmit green light are electrostatically adhered onto a photoreceptor 4 provided with a panchromatic photoconductive layer 3 on a substrate 2 having a conductive layer 1. and shows an optical path when red light r is irradiated through the particles. The particles R transmit the r light and irradiate the photoreceptor 3, and the electrostatic adhesion between the photoreceptor and the particles is weakened or eliminated. Now, particle G is originally r
absorb light. However, in general, the spectrum of transmitted light through a filter is wide. Furthermore, it is difficult to narrow the width of the transmitted light spectrum, and the transmittance decreases. Therefore, when the particles G have the spectral characteristics as shown in FIG. 2, the short wavelength component of the r light passes through the particles G and irradiates the photoreceptor 3, as shown in FIG. 1. Since the photoreceptor 3 is panchromatic,
The display charge on the photoconductor directly under the particles G also attenuates, and the electrostatic adhesion between the photoconductor 3 and the particles G after exposure also weakens. Therefore, the particles G are also easily removed during development.
Further, when the particles R have the spectral characteristics shown in FIG. 2 and 7, when green light is irradiated, the long wavelength component of the green light has the same effect as described above. As a result, there was a problem that the latitude was narrow. On the other hand, if particles R and G have the spectral characteristics shown in FIGS. 8 and 9, respectively, the reproducibility for red light and green light will be excellent, so the latitude will be widened for red and green. For light of a color having a dominant wavelength between the two, the transmittance of both particles R and G deteriorates, resulting in a decrease in color reproducibility, and for example, the latitude is narrow for full color reproduction. Furthermore, when a panchromatic photoreceptor is used, the narrower the particle size distribution, the better the color reproducibility and the wider the latitude, but the fewer the gradations. SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned conventional drawbacks and provide an image forming method with a wider latitude. Another object of the present invention is to provide an image forming method that provides better color particle images. Still another object of the present invention is to provide an image forming method for obtaining a color image faithful to the original by one exposure and one development. The present invention is an image forming method characterized in that light-transmitting particles are electrostatically deposited on a photoconductive layer that is primarily sensitive to transmitted light. Specifically, a support including a photoconductive layer formed by arranging patches of a plurality of types of photoconductive substances that are sensitive to light transmitted by one type of particle and almost insensitive to light transmitted by other types of particles. The image forming method is characterized in that the particles are electrostatically attached to the patch having a main sensitivity to the spectral transmission spectrum of the particles. Next, the image forming method of the present invention will be explained in detail based on the drawings. FIG. 3 is a diagram illustrating the basic configuration of the image forming method of the present invention. That is, a patch R of a photoconductive material sensitive to red and a patch G of a photoconductive material sensitive to green are connected to a substrate 2 having a conductive layer 1.
Particles R on the patch R of the photoreceptor 10 arranged in
shows the optical path when particles G are electrostatically attached onto patch G and red light r is irradiated through the particles. As explained in FIG. 1, the irradiation light r passes through the particles R. This transmitted light 11 illuminates the red-sensitive photoconductive material patch R , the surface charge of the patch R is attenuated, and the electrostatic adhesion between the photoreceptor 10 and the particles R is weakened or eliminated. On the other hand, as for the particles G, as explained in FIG. However, the photoconductive material directly under the particle G is sensitive to green. Therefore, even when the patch G is irradiated with the transmitted light 6, the attenuation of the surface charge of the patch G is extremely small, and the electrostatic adhesion between the particles G and the photoreceptor 9 is strong even after exposure. Therefore, even during development, particles G
is not removed. At the same time, when the exposure amount is increased, the amount of transmitted light 6 also increases, but since patch G has almost no sensitivity to transmitted light 6, patch G
The decay of surface charge is small. In other words, the latitude widens. Furthermore, even if the particles R and G are wider than the spectral characteristics shown in FIGS. 5 and 7, a particle image with high purity and high color density can be reproduced with the expanded latitude. Furthermore, even when the irradiation light has a dominant wavelength between red and green, the green component of the irradiation light
The inner red component of the irradiated light passes through the particles R and attenuates the surface charge of the patch R. Therefore, even intermediate colors between red and green can be reproduced with high color purity. Although we have explained particle R and particle G, and patch R and patch G , the same applies to particles and patches that exhibit spectral characteristics at other wavelengths, and the same effect can be obtained even if the number of types of particles and patches is changed. Of course, this can be obtained. Furthermore, the above explanation has been made regarding the case where red light, green light, and light having a dominant wavelength between red and green are used as the irradiation light, but it goes without saying that the same applies when light of other wavelengths is used as the irradiation light. It is.
Further, in the image forming method of the present invention, it is sufficient that the photoconductive substance directly under the light-transmitting particles has sensitivity to the light transmitted through the particles, and therefore the size and shape of the photoconductive patch are limited. It's not a thing. However, the short side or diameter of the patch determines the resolution. Next, materials used in the image forming method of the present invention will be explained. The particles are generally composed of resin. Examples of this resin include polyvinyl alcohol. Transparent resins such as thermoplastic resins such as acrylic resins, thermosetting resins such as melamine resins and phenolic resins, styrene-butadiene copolymers, and gelatin are used. Commercially available glass beads are also provided. By adding a coloring agent such as a dye or a pigment to the above-mentioned resin, a color separation function is imparted to the particles. Examples of typical colorants include CI acid red 6, 14, and 1 for red light transmission.
These include acid dyes such as CI Pigment Red 17, 48, and 81, and organic pigments such as CI Pigment Red 17, 48, and 81. For transmitting green light, acid dyes such as CI Acid Green 9, 27, 40, and 43, metal-containing dyes such as Eisenspiron Green C-GH (manufactured by Hodogaya Chemical Industry Co., Ltd.), or CI plastic dyes. There are organic pigments such as Gment Green 2 and 7.
For blue light transmission, oil dyes such as CI Solvent Blue 48, 49, direct dyes such as CI Direct Blue 86, acid dyes such as CI Acid Blue 23, 40, 62, 83, 120, CI Pigment Blue 15, etc. There are organic pigments such as Moreover, it goes without saying that other desired spectral characteristics can be obtained by mixing a single colorant or a plurality of colorants as necessary. Furthermore, by adding a sublimable dye, a coloring function can be imparted. In particular, colorless sublimable dyes are colorless or light-colored in normal conditions, sublimate when heated, and develop color by reacting with color developers such as activated clay, tartaric acid, and 4,4'-diphenylpropane. . Therefore, it is also possible to add, together with the colorant, a colorless sublimable dye that develops a complementary color to the colorant that imparts a color separation function to the particles. However, when using a colorless sublimable dye, it is of course necessary to use an image receptor having the above-mentioned color developer. Typical examples of colorless sublimable dyes include 3,
7-bis-diethylamino-10-trichloroacetyl-phenoxazine, 4-(1,3,3,5-
Tetramethyl-indolino)methyl-7-(N-
Methyl-N-phenyl)amino-1', 3', 3',
5'-Tetramethyl-spiro (2H-1-benzopyran-2,2'-[2'H]-indole), N-
(1,2-dimethyl-3-yl)methylidene-2,4
- Dimethoxyaniline, etc. Furthermore, the image forming method of the present invention performs image exposure through particles. Therefore, it is necessary to substantially align the optical paths of the irradiated light. That is, it is necessary to make the thickness of the particles substantially uniform in the vertical direction of the support including the photoconductive layer. As one means for this purpose, it is desirable that the particle surface has electrical conductivity in order to electrostatically adhere the particles almost uniformly to the support surface. When using non-conductive particle materials, conductive treatment is applied to the particle surfaces. At this time, it is required that the color separation of the particles is not affected. As this conductive material, copper iodide, polymer electrolyte, etc. are used. Further, the apparent resistivity of the particle surface is preferably in the range of 10 to 10 ¹⁰ Ω·cm. Next, as the photoconductive substance used in the present invention, zinc oxide, poly-N-vinylcarbazole, etc. are sensitized by conventional means in accordance with the color separation function of the particles. Next, the basic process of the image forming method of the present invention will be described in detail with reference to the drawings, citing one embodiment. FIG. 4 shows a photoreceptor 12 in which patches R , G , and B of photoconductive materials sensitive to red, green, and blue, respectively, are arranged on a substrate 2 having a conductive layer 1, and the photoreceptor 12 is charged in a dark place with, for example, a corona charger. 13 shows the step of uniformly charging. The photoreceptor 12 is prepared by preparing particles of a photoconductive substance sensitized to each color by a conventional method such as coating on the substrate 2 by gravure printing or spray drying, and applying the particles to a support containing a photoconductive layer. For each photoconductive material particle, the pattern is imagewise exposed, one type of the photoconductive particles is dispersed on the support, and then a photoconductive material layer matching the pattern is obtained by a method such as pressure bonding. It can be produced by normal means such as repeated methods. In FIG. 5, the photoreceptor 12 is
2 shows the process of electrostatically depositing particles R, G, and B that selectively transmit red, green, and blue light onto patches R , G , and B , respectively. For example, as shown in FIG. 6, after charging the photoreceptor 12 with a corona charger 13,
There is a method of electrostatically adhering one type of particles to the entire surface in step 5, scraping off the particles adhering to other patches with a doctor blade 16, and repeating this process to spread the particles.
An arrow 17 indicates the direction in which the photoreceptor 12 moves. FIG. 7 shows the patch R of the photoreceptor 12 using an ordinary electrostatic pin 18r.
Particles R are applied to the patches G and B by electrostatic pins 18, respectively.
A method is shown in which the particles G and B are charged by the particles G and 18b and are dispersed by the particle scattering devices 19g and 19b. In FIG. 8, the photoreceptor 12 is charged with the corona charger 13, and the particles R on the tray 20r are transferred to the electrode 21r to which a voltage is applied.
Then, particles G are sprayed onto patch R using tray 20g, electrode 21g, shielding plate 22g, and slit 23g, and particles B are sprayed onto patch R using tray 20g, electrode 21g, shielding plate 22g, and slit 23g. , the shielding plate 22b, and the slit 23b are used to spray the patch B. After particles are dispersed by any one of the above methods or a combination thereof, the original 24 is exposed to light through the particles, as shown in FIG. In the figure w, r,
g and b indicate white light, red light, green light, and blue light, respectively. Next, as shown in FIG. 10, when the photoreceptor 12 is vibrated with, for example, an electromagnetic vibrator 25, the particles that have passed through the light are removed because their electrostatic adhesion to the photoreceptor 12 has been weakened or eliminated. The particles are developed, and a particle image is obtained on the photoreceptor 12. In addition to the above-mentioned method of development using vibration, there are also methods in which an adhesive material is brought into close contact with the particles and developed using the adhesive force, a method in which development is performed using a flow pressure of a highly insulating solution such as mineral turpentine, and a method in which development is performed using electrostatic force. Ordinary means such as the method of
The above is the basic process of the image forming method of the present invention. Next, the image forming method of the present invention will be described with reference to specific examples. (1) Preparation of photoconductor A Photoconductor A As shown in FIG.
Mask 2 with a square hole of 40 μm on each side in 6
7 and deposit selenium (hereinafter referred to as Se), then move the mask 27 and deposit red-sensitive copper phthalocyanine (hereinafter referred to as Se) next to the Se patch.
CuPC) was deposited. The deposition thickness is Se,
The CuPC thickness was approximately 2 μm. B Photoreceptor B First, a photoconductive substance dispersion liquid was prepared according to the following formulation. 3 kg of zinc sulfide as a photoconductive substance, 500 g of acrylic resin as a binder, and 3 kg of toluene were added and mixed and dispersed in a ball mill for 24 hours, and the resulting solution was divided into three equal parts. The first solution contains diacidocyanine green as a red photosensitizer.
1 g of GWA, 0.5 g of rose bengal as a green photosensitizer in the second solution, and 1 g of uranine as a blue-violet photosensitizer in the third solution were thoroughly mixed separately. Using the three liquids mentioned above, apply 80% on the deposition surface of the aluminum deposition film by gravure screen printing.
It was printed in stripes of p/mm. C Photoreceptor C First, a photoconductive substance dispersion liquid was prepared according to the following formulation. A solution obtained by mixing and dispersing 3 kg of zinc oxide as a photoconductive substance, 450 g of an acrylic resin as a binder, and 3 kg of toluene in an attritor for 30 minutes was divided into three equal parts. The first solution contains 1.2g of methylene blue as a red photosensitizer, the second solution contains 0.3g of rose bengal as a green photosensitizer, and the third solution contains 1.2g of methylene blue as a red photosensitizer.
1 g of fluorescein as a blue-violet photosensitizer was added to the solution and thoroughly mixed separately. Using the three liquids mentioned above, apply 80% on the deposition surface of the aluminum deposition film by gravure screen printing.
It was printed in stripes of p/mm. D Photoreceptor D The three liquids in C) above were separately granulated by spray drying, and then classified to obtain photoconductive particles of 20 to 37 μm. Next, using a commercially available zinc oxide paper and the apparatus shown in FIG. 7, the photoconductive particles described above were scattered. Layer release paper on top of this, 10Kg/
When the release paper was removed by passing it through a calender roll heated to 100° C. and a nip pressure of 1 cm, a photoreceptor with a smooth surface in which the photoconductive particles were fused together was obtained. The R , G , and B patch widths at this time were approximately 50 μm. E Photoreceptor E As shown in FIG. 12, a rubber ring 29, for example, is wrapped around the aluminum drum 28 as a sealing material. When this was immersed in the first solution C) and dried, patches R were formed in the unsealed portions, as shown in FIG. 13. Thereafter, a portion of the seal 29 was cut off and immersed in a second liquid and then dried, and a portion of the seal 29 was cut off and immersed in a third liquid to obtain a photosensitive drum as shown in FIG. When the surface of this was polished, a photosensitive drum as shown in FIG. 15 was obtained. (2) Preparation of particles a Particle a 200 g 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 100g of glass beads with a particle size of approximately 20-50μm and 3g of formalin were added to each of these three types of gelatin aqueous solutions, and each was separately spray-dried and granulated, particles colored red, green, and blue were obtained. . b Particles b First, red, green, and blue-purple solutions were prepared according to the following formulations. A Red solution melamine resin binder Sumitekus Resin M
-3 (manufactured by Sumitomo Chemical Co., Ltd., the same hereinafter)
100 parts by weight curing accelerator Sumitex Accelerator
EPX (manufactured by Sumitomo Chemical Co., Ltd., the same hereinafter)
8 parts by weight Colored dye Methyl Orange 2 parts by weight Colored dye Eisen Rose Bengal B (CI
Assisted Dred 94) (manufactured by Hodogaya Chemical Industry Co., Ltd.)
2 parts by weight Water 100 parts by weight Green solution melamine resin binder 100 parts by weight Curing accelerator 8 parts by weight Colored dye Suminol Leveling Yellow NR
(CI Acid Yellow 19) (Sumitomo Chemical Co., Ltd.)
10 parts by weight Colored dye Kayacion Green A-4G (manufactured by Nippon Kagaku Co., Ltd.) 7 parts by weight Water 100 parts by weight C Blue-violet solution melamine resin binder 100 parts by weight Curing accelerator 8 parts by weight Colored dye Acid Bio Retto 6B (CI Assist Bioret 49) (Hodogaya Chemical Industry)
(manufactured by Co., Ltd.) 1.2 parts by weight Water 100 parts by weight The above-mentioned solutions (a) to (c) were separately spray-dried and granulated to obtain spherical particles with an average particle diameter of 15 μm.
Next, the polymer electrolyte quaternary ammonium salt type
To a solution of 10 parts by weight of ECR-34 (manufactured by Dow Chemical Company) and 90 parts by weight of water and thoroughly mixed, 100 parts by weight of the colored particles obtained above were added and separately spray-dried for conductive treatment. The specific resistance of the particles is approximately 10 ⁸ Ω・
It was cm. C Particles C Spherical particles granulated with Particles b were each separately fluid-coated with a colorless sublimable dye solution according to the following formulation. Thereafter, the same conductive treatment as for particle-b was performed. B Red particles Colorless sublimable dye that develops cyan color 3,7
50 parts by weight of a solution consisting of 10 parts by weight of -bis-diethylamino-10-trichloroacetyl-phenoxazine, 1 part by weight of ethyl cellulose as a binder, and 89 parts by weight of dichloroethane as a solvent were added to red particles.
Apply fluidly to 100 parts by weight. (b) Green particles Colorless sublimable dye that develops magenta color 4-
(5-chloro-1,3,3-trimethyl-indolino)methyl-7-(N-methyl-N-phenyl)amino-5'-chloro-1',3',3'-trimethyl-spiro[2H- 1-benzopyran-
15 parts by weight of a solution consisting of 10 parts by weight of (2H)-indole, 1 part by weight of ethyl cellulose, and 89 parts by weight of dichloroethane is fluidly applied to 100 parts by weight of green particles. C Blue-purple particles Colorless sublimable dye that develops a yellow color N-
(1,2-dimethyl-3-yl)methylidene-
50 parts by weight of a solution consisting of 10 parts by weight of 2,4-dimethoxyaniline, 1 part by weight of ethyl cellulose and 89 parts by weight of dichloroethane is fluidly applied to 100 parts by weight of blue-violet particles. Example 1 Photoreceptor A was positively charged in a dark place with a corona charger applying a voltage of +6 to 7 KV, and red light was irradiated for 0.3 seconds using a 500W tungsten lamp as a light source.
When blue particles among particles a were sprayed, photoreceptor A
Particles were electrostatically deposited on the Se patch. Next, the photoreceptor is positively charged again with the corona charger,
When red particles among particles a were sprinkled, photoreceptor A
Red particles were electrostatically deposited on the CuPC patch. After exposing the color original to light using a 500W tungsten lamp as a light source, the photoreceptor is vibrated to shake off the particles that have passed through the light, resulting in a color-separated particle image with very little fog on the photoreceptor. It was done. At this time, the exposure amount was such that at least the particle concentration was maintained from 1 to 15 seconds. Furthermore, the gradation had 9 steps. Example 2 Photoreceptor B was negatively charged in a dark place with a corona charger applying a voltage of -6 to -7 KV, and yellow light was irradiated for 0.5 seconds using a 500W tungsten lamp as a light source to remove blue particles among particles a. When sprayed, blue particles electrostatically adhered to patch B. This photoreceptor was negatively charged by the corona charger, irradiated with red light for 0.7 seconds, and green particles among particles a were scattered, and the green particles electrostatically adhered to patch G. Furthermore, the photoreceptor was charged by the corona, and red particles among the particles a were scattered. Thereafter, imagewise exposure and development were carried out in the same manner as in Example 1, and a color-separated particle image with very little fog was obtained on the photoreceptor. Similar particle images were also obtained for photoreceptors C and D and particle b. These results are summarized in Table 1.

[Table] Example 3 Particles were dispersed using the scattering device shown in FIG. 7, and the image exposure and development described in Examples 1 and 2 were performed, and the same results as in Table 1 were obtained. Example 4 A particle image was formed using particles c in the same process as in Example 3. After that, clay paper was brought into close contact with the particle image, heated at 170-200°C for 10 seconds, and the clay paper was peeled off.A color image faithful to the original with extremely little fog was reproduced. The results are shown in Table 2.

[Table] Example 5 As shown in FIG. 16, a color image was reproduced using a copying machine using photoreceptor E as the photoreceptor 30 and the apparatus shown in FIG. 8 as the dispersion section 31. That is, the photoreceptor 30 is negatively charged by the corona charger 13 to which a voltage of -6KV is applied, particles c are scattered by the scattering section 31, and the color original 32 is imaged through the optical system 34 using a 500W tungsten lamp as the light source 33. Expose. Thereafter, the dielectric roller 3 is positively charged by the corona charger 35 to which a voltage of +6KV is applied.
Electrostatic development is performed by step 6. Particles attached to the dielectric roller 36 are cleaned by a blade 37.
Thereafter, the particles are transferred to the clay paper 38 using normal means, heated at 170° C. for 10 seconds by the heater 39, and the particles on the clay paper 38 are cleaned with a fur brush 40, so that the clay paper 38 has a color faithful to the original 32. The image has been reproduced. As is clear from the above, the image forming method of the present invention has the effect of reproducing a color image faithful to the original. Furthermore, the image forming method of the present invention has the effect of extremely reducing fog. The image forming method of the present invention can reproduce a color image faithful to the original even if the transmitted light spectrum of the particles is broad. Therefore, the fidelity is high even for full-color originals, and there is an effect that a wide range of coloring materials can be selected for the particles. Further, in the image forming method of the present invention, since the color separation function of the particles corresponds to the sensitivity of the photoconductive substance directly under the particles, color separation is achieved by the synergistic effect of the particles and the photoconductive substance. Therefore, there is an effect of widening the latitude. At the same time, good image quality can be obtained even if the particle size distribution is broad, and there is an effect that the number of gradation steps is excellent.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the conventional image forming method, Figure 2 is a diagram explaining the spectra of particles, and Figure 3 is a diagram explaining the spectra of particles.
The figure is a diagram explaining the principle of the image forming method of the present invention.
Figures 4, 5, 9 and 10 are diagrams explaining the process of the image forming method of the present invention, and Figures 6 to 8 are diagrams explaining examples of the dispersion method applied to the present invention. 11 to 15 are diagrams illustrating an example of a method for manufacturing a photoreceptor applied to the present invention, and FIG.
The figure is a diagram illustrating an example of a copying apparatus for the image forming method of the present invention. 1... Conductive layer, 2... Substrate, 3... Photoconductive layer,
4, 10, 12... Photoreceptor, 13... Corona charger, 14, 15, 19... Particle scattering device, 16...
...Doctor blade, 18...Electrostatic pin, 24...
...Manuscript, 25...Electromagnetic vibrator.

Claims (1)

[Claims] 1. A step of charging a support including a photoconductive layer, a step of electrostatically adhering a plurality of types of light-transmitting particles having a color separation function to the support, and imagewise exposure through the particles. and then removing the particles whose electrostatic adhesion to the support has been weakened or removed from the support, the image forming method comprising the step of removing the particles from the support, wherein the particles are transferred to a photoconductive layer having primary sensitivity to transmitted light. An image forming method characterized by electrostatic deposition. 2. Claim 1, characterized in that the thickness of the light-transmitting particles electrostatically adhered to a support including a photoconductive layer in the vertical direction of the support is substantially uniform.
Image forming method described in section. 3. The image forming method according to claim 1, wherein the surface of the light-transmitting particles is electrically conductive. 4. The image forming method according to any one of claims 1 to 3, wherein the light-transmitting particles contain a sublimable dye. 5. The image forming method according to claim 4, wherein the sublimable dye is a colorless sublimable dye that develops color by reacting with a color developer.