JPH0446421B2 - - Google Patents

Description

[Detailed description of the invention]

B. Field of Industrial Application The present invention relates to an image forming method and a photoreceptor used in this method, and particularly to an image forming method suitable for forming a multicolor image using electrophotography and a photoreceptor used in this method. Regarding. B. Prior Art Many methods and devices used therefor have been proposed in the past for the purpose of obtaining multicolor images using electrophotography, but they can generally be classified into the following types. One method is to repeatedly form a latent image and develop with color toner according to the number of separated colors using a photoconductor, or to overlap the colors on the photoconductor, or to transfer the colors to a transfer material each time the development is performed. This is a method of layering. Another method uses a device having multiple photoconductors corresponding to the number of separated colors, exposes each photoconductor with a light image of each color at the same time, and uses color toner to cover the latent image formed on each photoconductor. In this method, the images are developed and sequentially transferred onto a transfer material to overlap the colors to obtain a multicolor image. In the former method, the latent image formation and development process must be repeated multiple times, and the major drawback is that it takes time to record the image, and that it is extremely difficult to speed up the process. In addition, in the case of overlapping toner images on the photoreceptor, the potential drop in the previously developed toner adhering area is not sufficient, so the toner to be developed later adheres to the previously developed toner that should not originally adhere. It also has the disadvantage that it tends to adhere to parts and cause color turbidity. The latter method uses multiple photoreceptors in parallel, which is advantageous in terms of speed, but requires multiple photoreceptors, an optical system, a developing means, etc., making the device complex, large, and expensive. Therefore, there is a drawback that it is not practical. Furthermore, both types have a major drawback in that it is difficult to align images when image formation and transfer are repeated multiple times, and color shift of images cannot be completely prevented. In order to fundamentally solve these problems, it is sufficient to record a multicolor image on a single photoreceptor with one image exposure, but the reality is that such a system has not yet been developed. C. Purpose of the Invention The present invention has been made in view of the above-mentioned circumstances, and is capable of forming a plurality of color-separated latent images through a single image exposure, thus preventing color shift from occurring. An image forming method capable of forming a high-quality multicolor image at high speed and in a simple process without causing the toner to be developed later to adhere to the previously developed toner-attached portion, and this method. The purpose is to provide a photoreceptor for use in D. Structure of the Invention The first invention (A) uses a photoreceptor according to the second invention described below, and (B) charges from the side of the layer having multiple types of color separation filter portions and generates charges on the lower layer side. (C) forming a uniform negative or positive surface potential on the surface of the photoreceptor by uniformly exposing the layer to light; Image exposure is performed to irradiate the charge generation layer from the side to the upper layer side, and (D) the entire surface of the charge generation layer on the upper layer side is irradiated with specific light to form a potential pattern in the portion corresponding to the color separation filter. It relates to an image forming method in which the steps of forming and developing are repeated. A second invention is a photoreceptor comprising a layer having a plurality of types of color separation filter portions and a photoconductive layer, the surface side of which is insulating, wherein the photoconductive layer contains a charge generating substance. The charge transfer layer comprises first and second charge generation layers and a charge transfer layer containing a charge transfer substance, and the charge transfer layer is capable of transferring only either holes or electrons. The image forming method according to the first invention, wherein the charge transfer layer is interposed between the first and second charge generation layers, and these layers constitute the photoconductive layer having a laminated structure. This relates to photoreceptors used in E. Embodiments The present invention will be described below with reference to illustrated examples. In addition, all the illustrated examples are color separation filters (filters that transmit only light in a specific wavelength range), such as red, which transmits red light, green light, and blue light, respectively.
Three types of filters, green and blue, and the corresponding three
Although an example using various color toners is shown, the present invention is not limited to the number of types of color combinations. 1 to 5 are sectional views schematically showing the structure of the photoreceptor used in the present invention, FIGS. 6 to 10 are sectional views similar to the above showing reference examples, and FIGS. FIG. 13 is a plan view showing an example of the filter arrangement of the filter distribution layer in the insulating layer of the photoreceptor, FIGS. 14 and 18 are schematic configuration diagrams showing an example of an apparatus for carrying out the method of the present invention, and FIG.
Fig. 16 is a process diagram of the method of the present invention, Fig. 17
The figure is a graph showing how the surface potential of the photoreceptor changes over time in accordance with the process. FIG. 19 is a sectional view of the developing device. In FIGS. 6 to 10, two layers (layer 2a to be described later) containing a charge generating substance are shown.
and 2b) and a layer containing a charge transfer substance (layer 2c described below), a single layer containing both a charge generation substance and a charge transfer substance ( Layer 2d) described below is used. In Figures 1 to 10, 1 is made of metal such as aluminum, iron, nickel, copper, or an alloy thereof, or a conductive film, etc., and is formed into an appropriate shape as required, such as a cylindrical shape, an endless belt shape, a sheet shape, etc. , a conductive substrate formed into a structure, 1-2 a transparent conductive layer formed by vapor-depositing these metals or alloys, 2 a photoconductive layer (details will be described later), 3 various polymers, resins, etc. and pigments, etc. This is an insulating layer including a distribution layer 3a of color separation filters of red (R), green (G), blue (B), etc. formed of colorants such as dyes. Figures 1 and 6
The insulating layer 3 of the photoreceptor shown in the figure is formed by printing an insulating material such as a resin colored with a coloring agent to form a color separation filter onto the photoconductive layer 2 in a predetermined pattern. The insulating layer 3 in the photoreceptors shown in FIGS. 2 and 7 is formed by first forming a transparent insulating layer 3b on the photoconductive layer 2 by a conventionally known means, and then coloring the surface of the insulating layer 3b. Formed by adhering agents, colored resins, etc. in a predetermined pattern by printing, vapor deposition, etc.
The insulating layer 3 in the photoreceptor shown in FIGS. 2 and 8 is formed by further providing a transparent insulating layer 3b on the insulating layer 3 shown in FIGS. 2 and 7 by conventionally known means, and FIG. The insulating layer 3 in the photoreceptor shown in FIGS. 9 and 9 can be formed by depositing a coloring agent on the photoconductive layer 2 in a predetermined pattern by direct printing, vapor deposition, or the like, or by depositing the coloring agent on the photoconductive layer 2 in a predetermined pattern, or by depositing the coloring agent on the photoconductive layer 2 in a predetermined pattern, or by depositing the coloring agent on the photoconductive layer 2 in a predetermined pattern, or as shown in FIGS. 1 and 6, respectively. Insulating layer 3
A transparent insulating layer 3b is provided thereon, similar to the insulating layer 3 in FIGS. 3 and 8. The formation of the insulating layer 3 is not limited to the above example; first, an insulating film or sheet containing the distribution layer 3a of the color separation filter is formed, and then it is attached or attached onto the photoconductive layer 3 by an appropriate means. It may also be adhesive. Further, the photoreceptor can have a structure as previously proposed by the applicant (Japanese Patent Application No. 199547/1982). For example, as shown in FIGS. 5 and 10, a transparent insulating layer 3c is provided on one surface of the photoconductive layer 2, and an insulating layer 3a consisting of a transparent conductive layer 1-2 and a color separation filter is provided on the other surface. It has a structure in which these are sequentially deposited and laminated. The transparent conductive layer 1-2 is formed, for example, by vapor depositing a metal. In the photoreceptor having this structure, charging, which will be described later, is performed from the insulating layer 3c side, and image exposure and full-surface exposure are performed from the insulating layer 3a side, which is a color separation filter. Distribution layer 3 of a color separation filter formed by adhesion of colorant, colored resin, etc. on the insulating layer 3
Although the shape and arrangement of fine filters such as R, G, and B are not particularly limited, a has a stripe-like distribution as shown in FIG. 11 because it is easy to form a pattern. A mosaic distribution as shown in FIGS. 12 and 13 is preferable in that a fine multicolor image can be reproduced. R,G,
The direction in which the filters such as B are arranged may be of course not only a mosaic distribution but also a stripe distribution and may be oriented in any direction in the spreading direction of the photoreceptor. That is, for example, in the case of a rotating drum-shaped photoreceptor, the length direction of the stripes may be parallel to or perpendicular to the axis of the photoreceptor, or may be spiral. The types of filters are not limited to the three types, R, G, and B, but also three types of other colors, such as Y (yellow),
It may be M (magenta), C (cyan),
Further, when used for two colors instead of full color, a color separation filter may be used in which a white light transmitting portion and a specific color light (for example, red) transmitting portion are distributed. If the individual sizes of filters such as R (red), G (green), and B (blue) become too large, image resolution and color mixing will decrease, resulting in deterioration of image quality, and if they become too small, toner Even if the particle size is the same as or smaller than the particle size, it becomes more susceptible to the influence of other adjacent color parts and it becomes difficult to form the distribution pattern of the filter. In the case of the filter distribution, it is preferable that the width or size is such that the lengths l ₁ and l ₂ of one cycle of the repeating arrangement are 30 to 500 μm. Of course, if the number of types of filters changes, the preferred ranges of the above-mentioned lengths l ₁ and l ₂ will also change. Note that each filter preferably has high resistance. If the resistance is low, they can be electrically insulated from each other by providing a gap or interposing an insulator. Note that the filter in the case of the structure of the photoreceptor shown in FIGS. 5 and 10 may have a low resistance. One of the features of the photoreceptor according to the present invention is the structure of the photoconductive layer. A photoconductive layer consisting of a single layer is widely used, but a photoconductive layer consisting of a single layer has the following problems. () When injecting charge from a conductive substrate,
The choice of materials for the substrate and photoconductive layer is constrained. For example, aluminum substrates are not preferred for selenium photoconductive layers, and nickel substrates are preferred. () A panchromatic spectral sensitivity distribution is desired for multicolor image formation, but such a photoconductive layer generally has a low charge retention ability and large dark decay. From this point of view, the present invention has two layers: a layer containing a charge generation substance (charge generation layer (CGL)) and a layer containing a charge transfer substance (charge transfer layer (CTL)). A photoconductive layer or a photoconductive layer having a layer containing both a charge generation material (CGM) and a charge transfer material (CTM) (hereinafter referred to as a (CGM+CTM) layer) is used. A photoreceptor constructed in this way has the advantage of easily obtaining a panchromatic spectral sensitivity distribution that matches the light source and filter, has a wide range of material selection, and has good charge retention ability. It is. However, in the image forming method based on the present invention, when a photoreceptor is used in which a conductive substrate, CGL, CTL, and an insulating layer having a mosaic filter are laminated in this order, charging and uniform exposure (for example, by white light) are required. A charge is generated in the CGL by uniform exposure (uniform exposure), moves through the CTL layer, and accumulates at the interface between the insulating layer and the photoconductive layer. The charges that are generated in the CGL and should move toward the insulating layer cannot move in the CTL because they have the opposite polarity to the charges that were generated in the previous process (CTL is normally an electron There are two types: a transfer type and a hole transfer type, in which only one of electrons and holes moves.) Therefore, it does not have photosensitivity. As a result of extensive research, the present inventor has discovered that by configuring the photoconductive layer as in the first invention described above, the advantages of the photoconductive layer described above in which the functions of charge generation and charge transfer are shared can be realized. We have succeeded in developing a photoreceptor and image forming method that can be used for a long time and can be used to form multicolor images. The structure of the photoreceptor based on the present invention is shown in FIGS. 1 to 10.
An example is shown in the figure. Its structure is roughly divided into two types. In one method, as shown in FIGS. 1 to 4, a first CGL 2a, a CTL 2c, and a second CGL 2b are sequentially laminated on a conductive substrate 1, and a photoconductive layer 2 is formed by these. , or as shown in FIG. 5, the second CGL2b, CTL2c,
The first CGLs 2a are sequentially laminated to constitute the photoconductive layer 2. The other one is a CGL 2a similar to the first CGL, which is placed on the conductive substrate 1 as shown in FIGS.
(CGM+CTM) layers 2d are laminated in sequence to form the photoconductive layer 2, or the second layer 2d is laminated on the transparent conductive layer 1-2 as shown in FIG.
CGL2b similar to CGL, (CGM+CTM) layer 2d
The photoconductive layer 2 is constructed by sequentially laminating the photoconductive layer 2. As a desirable embodiment of the present invention, during image exposure, charges are generated in the CGL 2b or (CGM+CTM) layer 2d located on the image exposure light irradiation side, that is, located on the filter side, and when charge is injected prior to image exposure, on the image exposure light irradiation side. Electric charges are generated in the CGL 2a or (CGM+CTM) layer 2d located on the opposite side. The reason is as follows. If a charge is generated in the CGM2a on the opposite side to the imagewise exposure light irradiation side ((CGM+CTM) layer 2d in Figure 10) during imagewise exposure, the imagewise exposure light will be absorbed by the CGM2b in front of it, and the light This causes a significant decrease in sensitivity and changes in spectral sensitivity, making it difficult to obtain high-quality images. By generating charges in the layer on the imagewise exposure light irradiation side as described above, absorption of the imagewise exposure light midway is almost negligible, and charge generation is sufficiently performed. Furthermore, even if a portion of the uniform exposure light is absorbed by the second CGL 2b during charge injection prior to image exposure, this uniform exposure will have a negative effect on the resulting image since it is sufficient to inject charge. There aren't many. In order for uniform exposure light to be used effectively, charge generation by these layers has a wider or different spectral sensitivity distribution than the first CGL 2a or (CGM+CTM) layer 2d (for example, has sensitivity in a long wavelength region). ) is more desirable. If the charge generation layers 2a and 2b are too thick, satisfactory photosensitivity cannot be obtained, and the thickness of both is 0.001 to 0.001.
A range of 10 μm is appropriate, and it can be formed by a vapor deposition method, a coating method, or the like. The layer containing the charge-generating substance 2g and the charge-transferring substance 2t, that is, the (CGM+CTM) layer 2d, is preferably formed as follows. An amount of 2 g of charge generating material (CGM) was applied in the vicinity of the insulating layer 3 by imagewise exposure.
The photoreceptor shown in the figure requires a sufficient amount of charge to be generated (during charge injection). Its compounding amount is (CGM+
CTM) layer 2d is preferably about 0.05 to 50% by weight. Note that the charge generation layers 2a and 2b are made of the above-mentioned (CGM+
CTM) layer 2d of charge generation material 2g and charge transfer material 2t (these materials will be explained in detail later).
and a binder resin, and it is more preferable that the amount of charge generating material (2 g) is increased to about 30 to 95% by weight. Next, the materials of each layer constituting the photoreceptor will be explained. As the material of the conductive substrate 1, for example, a metal substrate such as nickel brass or aluminum can be used, but a vapor-deposited layer formed by vapor-depositing a metal or the like on paper or plastic film can also be used. First charge generation layer 2a, second charge generation layer 2c
and charge generating substance 2 in (CGM+CTM) layer 2d
Materials for g include Se, Se-Te, Se-Te-As
In addition to inorganic compounds such as metals such as CdS, ZnS, CaSe, and ZnO, the following organic dyes can be used. (1) Phthalocyanine dyes such as metal phthalocyanine and metal-free phthalocyanine However, Me: Metal such as Cu (2) Azo dyes such as monoazo dyes and disazo dyes (3) Perylene dyes such as perylene anhydride and perylene imide A= O, NH, N-CH ₃ , N-CO ₂ H ₅ , etc. (4) Indigo and thioindigo-based indigoid dyes (5) Antoanthrone, dibenzpyrenequinone,
Polycyclic quinone dyes such as pyrantrone, violanthrone, isobiocinthrone, etc. However, X: Halogen (6) Anthraquinone dye (7) Quinacridone dyes (8) Cyanine dye (9) Benzimidazole-based dye (10) Dioxane-based dye A charge-generating substance layer made of an inorganic or organic dye may be formed by vapor deposition or by bonding the charge-generating substance and binder resin with specific or non-specific polarity as necessary. It is provided by applying a solution containing a substance having high mobility for the charge, that is, a charge transfer substance (details will be described later). The thickness of the charge generation layer is suitably 0.001 to 10 .mu.m, particularly preferably 0.05 to 5 .mu.m. Examples of the binder resin include addition polymer resins such as polyethylene, polypropylene, acrylic resins, methacrylic resins, vinyl chloride resins, vinyl acetate resins, epoxy resins, polyurethane resins, phenolic resins, polyester resins, alkyd resins, and polycarbonate resins; Addition type polymer resins, polymer bond type resins, and copolymer resins containing two or more of the repeating units of these resins,
Examples include vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-maleic anhydride copolymer resin, and the like. However, the binder resin is not limited to these, and resins commonly used for such purposes can be used. The charge-generating substance contained in the second charge-generating layer 2a may be any material that absorbs light in the entire visible range and generates free charges in consideration of color reproduction. The spectral sensitivity of the first charge generation layer 2a on the side of the conductive substrate 1 is as follows:
It is very convenient to make it wider than that of the second charge generation layer 2b on the insulating layer 3 side or to shift the spectral sensitivity distribution. That is, since the second charge generation layer 2b generates charges by imagewise exposure, it is desirable to have spectral sensitivity in the visible range.Therefore, the first charge generation layer 2a generates charges by the second charge generation layer 2b. In order to generate charges by the exposure light that passes through the entire surface without being absorbed, it is desirable to have spectral sensitivity even in the region that is not absorbed by the second charge generation layer 2b.
It is desirable to have spectral sensitivity not only in the visible region but also in the infrared region and/or ultraviolet region. By setting the spectral sensitivity as described above, the influence of absorption of the entire surface exposure light by the second charge generation layer can be reduced. First charge generation layer 2a and second charge generation layer 2b
The above relationship of the spectral sensitivity distribution with
The same applies to the charge generation layer 2a and the (CGM+CTM) layer 2d in the figure. The charge transfer layer 2c is the charge generation layer 2a, 2b.
It has the function of transferring either positive or negative charges generated by absorbing light in the process, that is, it is mainly composed of a charge transfer material. The charge transfer layer 2c contains at least a charge transfer substance, and may further contain a binder resin, Lewis acid and/or Brønsted acid, etc., if necessary. For example, the charge transfer layer 2c can be formed by dissolving both of these in a solvent, applying this solution onto the first charge generation layer 2a, and drying it. The blending ratio of each component in the charge transfer layer 2c is as follows:
0 parts of binder resin per 100 parts by weight of charge transfer material
It is desirable that the binder resin be in the range of ~400 parts by weight, and particularly preferably 100 to 200 parts by weight of the binder resin. The thickness of the charge transfer layer 2c is 10 to 100 μm, particularly preferably 20 to 50 μm. The charge transfer substance in the charge transfer layer 2c and (CGM
Although various materials can be used as the charge transfer substance 2t in the +CTM) layer 2d, specific examples thereof are as follows. (1) Arylalkane-based substances (P-type) for example (2) Pyrazoline substances (P type)

[Formula] (General formula) For example (3) Oxadiazole substances (P type)

[Formula] (General formula) For example (4) Hydrazone-based substances (P-type)

[Formula] (General formula) For example (5) Styryl substance (P type) R ₁ − (CH=CH) _o --Ar (general formula)

【formula】

【formula】

【formula】

【formula】

[Formula] Y=O, S, R=alkyl Ar=substituted or unsubstituted phenyl For example (6) Triphenylamine-based substances (P-type)

[Formula] (General formula) For example (7) Phenylenediamine-based substances (P-type)

[Formula] (general formula) (8) Biphenylamine substances (P type)

[Formula] (General formula) For example (9) Carbazole substances (P type)

[Formula] (General formula) For example (10) Fluorenone derivatives (N-type) such as trinitrofluorenone (TNF) These charge transfer substances 2t are included in the charge generation layer 2.
It can be used included in a and 2b. Also,
The binder resin used in the charge generation layers 2a and 2b can be used. The insulating layer 3 having the layer 3a made of color separation filters has already been described. The image forming apparatus shown in FIG. 14 forms a multicolor image by the method of the present invention using a drum-shaped image carrier 4 made of the photoreceptor as described above.
That is, the image carrier 4 rotates in the direction of the arrow, and the charger 5 charges it to a uniform potential while uniformly exposing its surface, and the image exposure device 6 scans the document with white light on the charged surface. Image exposure is performed by making reflected light or transmitted light incident through a slit in the charger while charging it with an alternating current or a charger that generates corona discharge of the opposite sign to the charger 5, and then coloring the charged surface. Exposure device 7B is a blue filter
The blue light L _B that has passed through F _B is incident uniformly, thereby forming an electrostatic latent image that provides a complementary color image of blue on the above-mentioned image exposure surface. A developing device 8Y using a developing device 8Y develops the image, and a charging device 9Y that performs a corona discharge similar to the charging device of the image exposure device 6 discharges the image carrier 4 after development to smooth the potential of the image carrier 4, The color exposure device 7G uniformly injects the green light L _G that has passed through the green filter F _G onto the potential smooth surface to form an electrostatic latent image that provides a green complementary color image, and the electrostatic latent image is transferred to the developer. A developing device 8M using magenta toner performs development, and a charger 9M similar to the charger 9Y performs corona discharge on the image carrier 4 after development to smooth the potential of the image carrier 4. The color exposure device 7R uniformly enters the red light L _R that has passed through the red filter F _R to form an electrostatic latent image that provides a complementary color image of red, and uses the electrostatic latent image as a developer using cyan toner. The developing device 8C using the above develops the image, thereby forming a multicolor image consisting of a superposition of three color toner images of yellow, magenta, and cyan on the surface of the image carrier. This multicolor image is transferred by a transfer device 10 to a recording paper P fed by a paper feeding device (not shown), and the transferred recording paper is transferred to the four surfaces of the image carrier by a separator 11. The multicolor image is fixed by a fixing device (not shown) and then discharged outside the machine. The surface of the image carrier 4 to which the multicolor image has been transferred is neutralized by a static eliminator 12 that performs exposure and discharge, residual toner is removed by a cleaning device 13, and the next multicolor image is formed again. Return to state. Each step of the multicolor image forming method of the present invention performed by the apparatus shown in FIG. 14 as described above will be further explained with reference to FIGS. 15 and 16. 15 and 16, a photoreceptor having the structure shown in FIG. 1 is used as the image carrier 4, and a material having hole mobility is used for the charge transfer layer 2c constituting the photoconductive layer 2. In FIGS. 15 and 16, the same reference numerals as in FIGS. 1 and 11 to 13 indicate the same functional members. Also, Figures 2 to 10
There is no difference in principle even when a photoreceptor having the structure shown in the figure is used. FIG. 15 is a diagram illustrating the generation and movement of charges in the process from charge injection to full-surface exposure with specific light. As shown in FIG. 15, when uniform exposure with white light, infrared light, etc. from a light source 5b is performed simultaneously with negative discharge by the charger 5a of the primary charging device 5,
While negative charges accumulate on the surface of the insulating layer 3, positive and negative charges are generated in the first CGL 2a by the uniform exposure light, and these positive charges pass through the CTL 2c into the second CGL 2b. and move. At the same time, the negative charge generated in the first CGL 2a escapes to the ground circuit through the conductive substrate 1 and disappears. Therefore,
The above white light or infrared light is the first CGL2a.
It needs to be irradiated so that it reaches . Next, as shown in FIG. 15 2, when image exposure is performed while positive or alternating current corona discharge is being performed by the secondary charger 6, red light L _R is irradiated. , the negative charges on the surface of the insulating layer 3 are partially dissipated by positive or alternating current corona discharge in areas other than the R filter portion. In the R filter section, the red light L _R passes through the R filter section and enters the second
Positive and negative charges are generated to irradiate the CGL 2b, and while the negative charges neutralize the trapped positive charges, the generated positive charges pass through the CTL 2c, the first CGL 2a, and the conductive substrate 1. In order to escape to the ground circuit, the positive charges in the second CGL 2b disappear, and the negative charges on the surface of the insulating layer 3 also substantially disappear. Next, as shown in FIG. 15, when the entire surface is exposed to blue light L _B , there is no change because the blue light L _B does not pass through the parts other than the B filter part, but the blue light L _B does not pass through the parts other than the B filter part. is transmitted, and a portion of the positive charge in the second CGL 2b below passes through the CTL 2c and the first CGL 2a to neutralize the negative charge on the photoconductive layer 2 side of the conductive substrate 1. As a reference example, in the photoreceptor having the structure shown in FIGS. 6 to 10, the (CGM+CTM) layer 2d has holes,
Since both electrons are movable, Fig. 15 1,
In step 2, both + and - charges become (CGM+
CTM) layer 2d, and if +,
Even if it is possible to move only one of the negative charges (CGM+CTM), charges of opposite polarity will neutralize each other near the interface between the (CGM+CTM) layer 2d and the CGL 2a or 2b. As a result, in any case, Fig. 15 1,
It is difficult to reliably achieve a charge distribution like 2. FIG. 16 shows a state in which the image carrier 4 rotates and is uniformly charged by uniform exposure and negative corona discharge from the charger 5, and the surface of the insulating layer 3 is negatively charged. Correspondingly, positive charges transferred from the first charge generation layer are induced at the interface between the photoconductive layer 2 and the insulating layer 3, and as a result, the surface of the image carrier 4 has a potential E.
It shows a uniform potential as shown in the graph. In addition, in FIG. 16, each layer constituting the photoconductive layer 2 is not shown. FIG. 16 2 shows the change in the charged surface due to the red component L _R of the original image exposure incident on the charged surface by the image exposure device 6, and the red component L _R is the R of the insulating layer 3.
Passing through the filter part, charges are generated in the second charge generation layer in the photoconductive layer 2 below, and the positive charges trapped by the negative charges are dissipated, while the generated holes are transferred to the conductive substrate. As a result, in that part, the positive charges on the interface between the photoconductive layer 2 and the insulating layer 3 disappear, and the negative charges on the surface of the insulating layer 3 are also erased by the discharge from the charger of the image exposure device 6. (For the purpose of explaining the principle, we will focus on the strong red component L _R. ) On the other hand, since the G and B filter portions do not pass the red component L _R , the negative charge of the photoconductive layer 2 remains in those portions, and even if discharge is performed by the discharger, the image exposure device 6
After passing through the position, negative charges remain on the surface of the insulating layer 3 due to the positive charges of the photoconductive layer 2. but,
The surface potential of the image carrier 4 due to positive and negative charges is balanced to the potential E not only in the R filter portion where the charge has disappeared but also in the G and B filter portions where the charge remains.
As shown in the graph, it is almost 0. Although not shown in FIG. 16, the green and blue components of image exposure give similar results, and their integrated state is the state of image exposure performed by image exposure device 6. In this state, a primary latent image that does not function as an electrostatic image is formed. FIG. 16 shows a state in which the blue light L _B passed through the blue filter F _B by the color exposure device 7B is uniformly incident on the above-mentioned image exposure surface. Blue light L _B is
The R and G filter parts do not pass through, so there is no change in those parts, but the B filter part passes through and makes the photoconductive layer 2 below it conductive, thereby making the photoconductive layer 2 in that part conductive. The charges at the upper and lower interfaces of are neutralized, and as a result, a potential appears on the surface of the insulating layer 3 at the B filter portion, as shown in the graph of potential E, which provides a complementary color image of B formed by the previous image exposure. It becomes like this. The steps up to this point are the same as those already explained with reference to FIG. FIG. 16 4 shows a developing device 8 in which an electrostatic latent image formed by full-surface exposure to blue light L _B is negatively charged and uses yellow toner TY, which is the complementary color of B, as a developer.
The state after development with Y is shown. The yellow toner TY adheres only to the B filter portion that shows potential, and does not adhere to the R and G filter portions that do not show potential. As a result, a color-separated one-color yellow toner image is formed on the surface of the image carrier 4. The potential of the B filter part is yellow toner.
Although the potential decreases due to the adhesion of TY, it still remains as shown in the graph of potential E, and in the next development, another toner may adhere to this area, causing color smudging. In FIG. 16, a charger 9Y is placed on the surface of the image carrier 4 which has been developed by the developing device 8Y in order to prevent other toner from adhering to the B filter portion.
This shows the state where corona discharge is performed. This discharge by the charger 9Y, unlike the strong discharge by the charger 5, has little effect on the R and G filter portions, and mainly lowers the potential of the B filter portion to which the yellow toner TY is attached. Therefore, the surface potential of the image carrier 4 uniformly shows almost 0 as seen in the graph of the potential E. This prevents other toner from adhering to the B filter portion to which the yellow toner TY is adhering in the next developing process, thereby preventing color smearing. Therefore, when the surface of the image carrier 4 shown in FIG. 16, on which the yellow toner image has been formed, is exposed entirely with green light L _G by the color exposure device 7G,
As described in FIG. 16, an image potential appears in the G filter portion. When this electrostatic latent image is developed by a developing device 8M using magenta toner as a developer, the magenta toner adheres only to the G filter portion and a magenta toner image is formed as in FIG. 16 and 4. As a result, the two color toner images are superimposed. Corona discharge is also performed on this image forming surface by the charger 9M to lower the potential of the G filter portion to which the magenta toner is attached.
Prevent other toner from adhering to that area. These processes are shown in FIGS. 6, 7 and 8. Furthermore, even if the color exposure device 7R exposes the entire surface of the image carrier 4 on which the two-color toner images are formed with the red light L _R , no image potential appears in the R filter portion. , the electrostatic latent image is not developed by the developing device 8C using cyan toner as a developer, and no cyan toner image is formed. As a result, a clear red image consisting of yellow and magenta without color shift or color turbidity is formed on the image carrier 4. FIG. 16 above shows the photoconductive layer 2 of the image carrier 4.
An example is shown in which a hole transfer layer is used in the CTL2c, but it is of course possible to use an electron transfer layer in the photoconductive layer 2, and in that case, the positive and negative signs of the charges can all be reversed. All the basic processes are the same. Further, although the surface potential of the image carrier 4 after charging in FIG. 16 is set to almost 0, it may be slightly biased toward the negative or positive side. Table 1 shows the relationship between the colors of the original image and image formation using the three primary color toners using the above-mentioned three-color separation method.
In the table, 〓 indicates a primary latent image, ◯ indicates an electrostatic latent image, 〓 indicates a toner image, ↓ indicates a state in which the state in the upper column is maintained as it is, and a blank indicates a state in which no image exists. Further, in the attached toner column, - indicates that no toner is attached, and Y, M, and C indicate that yellow toner, magenta toner, and toner toner are attached, respectively.

【table】

[Table] Furthermore, Fig. 17 shows each filter part B of the photoreceptor,
It shows the situation in which the surface potentials in G and R change according to the above-mentioned image forming process, and 5, 5 on the horizontal axis
6, 7, 7B, 8Y, 9Y, 7G, 8M, 9M,
7R and 8C indicate the steps in which members with the same reference numerals as in FIG. 14 or 16 act on the image carrier 4, respectively, and B, G, and R indicate the maximum or average potential of each filter portion. The multicolor image forming apparatus shown in FIG.
A toner image of one color is formed by rotation,
full exposure by means of lamps with blue, green and red lights used either alternately or simultaneously;
The first point is that the surface potential of the image carrier 4 after development is made uniform by using the charger 6 of the image exposure device.
This is different from the multicolor image forming apparatus shown in FIG. Similar to the multicolor image forming apparatus shown in FIG. 14, this multicolor image forming apparatus also performs the same image forming operation as described with reference to FIGS. 15 and 16. It is possible to form monochromatic images with excellent resolution. That is, for example, when forming a three-color image, the image carrier 4 is charged by uniform exposure and charging 5a, image exposure is performed through the charger 6, and then a lamp 7 is applied to the surface of the image carrier 4. The entire surface is exposed to blue light, and the potential pattern formed thereby is developed by the developing device 8Y to form a yellow toner image. This toner image is transferred to developing devices 8M, 8C,
8K, pre-transfer charger 14, transfer device 10, separator 1
1. Passes through without being affected by the cleaning device 13 and charger 5. When the image carrier 4 on which the toner image has been formed reaches the position of the charger 6, it undergoes corona discharge to make the surface potential uniform, and the entire surface is exposed to green light obtained from the lamp 7, forming a potential pattern. be done. Subsequently, this is developed by the developing device 8M to form a magenta toner image. In the same way, the surface potential is made uniform, a potential pattern is formed using red light, and development is performed by the developing device 8C. If you want to obtain an even darker image, after the potential is smoothed, the entire surface is exposed using white light or toner. A potential pattern is formed by irradiating the filter with an infrared light lamp having high transparency, and development is performed by a developing device 8K, and a color toner image is obtained by adding black toner. This multicolor image forming apparatus has a simple configuration that is almost the same as a monochrome copying machine except for the increased number of developing devices, and has the advantage of being smaller and lower in cost. In FIG. 18, the same reference numerals as in FIG. 14 indicate the same functional members. A magnetic brush developing device as shown in FIG. 19 is preferably used as the developing devices 8Y to 8K in the multicolor image forming apparatus shown in FIGS. 14 and 18. The developing device shown in FIG. 19 includes a developing sleeve 81,
At least one of the magnet bodies 82 having N and S magnetic poles on the inner peripheral surface of the developing sleeve 81 rotates, and the developer is attracted from the developer reservoir 83 to the surface of the developing sleeve 81 by the magnetic force of the magnet body 82. Convey the developer in the direction of the arrow. Then, during the conveyance of the developer, the amount of conveyance is regulated by the layer thickness regulating blade 84 to form a developer layer, and the developer layer is formed on the image carrier 4 in the developing area where the developing sleeve 81 faces the image carrier 4. Develop according to the potential pattern. During development, a developing bias voltage is applied to the developing sleeve 81 by the bias power supply 80. Also, if you do not perform development as necessary (when development is turned off)
A bias voltage may also be applied to the developing sleeve 81 in order to prevent toner from transferring from the developing sleeve 81 to the image carrier 4 or from transferring the toner from the image carrier 4 to the developing sleeve 81. . In addition, when development is OFF, when development (when ON)
Either cut out the AC bias component and leave only the DC bias component, or leave it in a floating state.
The developing device is grounded, a DC bias having the same polarity as the toner is applied, or the developing device is separated from the image carrier. Moreover, these treatments can also be used in combination.
85 is a cleaning blade that removes the developer layer that has passed through the developing area from the developing sleeve 81 and returns it to the developer reservoir 83; 86 is a stirring blade that agitates the developer in the developer reservoir 83 to make it uniform and triboelectrically charges the toner. The means 88 is a toner supply roller that supplies toner from the toner hopper 87 to the developer reservoir 83. The developer used in such a developing device may be a so-called one-component developer consisting only of toner, or a two-component developer consisting of toner and a magnetic carrier. For development, a method may be used in which the developer layer is directly rubbed on the surface of the image carrier with a magnetic brush, but especially after the second development, to avoid damage to the formed toner image. Development methods in which the developer layer does not come into contact with the surface of the image carrier, such as U.S. Pat. It is preferable to use the method described in each specification of No. 58-238296. Among these methods, a one-component or two-component developer containing a non-magnetic toner with freely selectable coloring is used, an alternating electric field is formed in the development area, and development is performed without contact between the electrostatic image carrier and the developer layer. It is preferable to do this. In this non-contact development, the gap between the developing sleeve and the surface of the photoreceptor is set to be larger than the layer thickness of the developer layer on the developing sleeve (provided there is no potential difference between the two), and this gap, layer thickness Development is carried out under various conditions as described above. The color toner used for development is prepared using known techniques, consisting of known binding resins, organic and inorganic pigments, various chromatic and achromatic colorants such as dyes, and various magnetic additives, which are commonly used in toners. The carrier can be iron powder, ferrite powder, which are usually used for electrostatic images, resin-coated powder, or resin-coated toner with magnetic material dispersed in resin. Various known carriers such as magnetic carriers can be used. Also, the patent application filed earlier by the applicant in 1982
The developing methods described in No. 249669 and No. 240066 may be used. In the present invention, as a charger for charging the surface of the image bearing member that has been developed before every second and subsequent full-surface exposure, a charger that performs biased or unbiased AC corona discharge is used. , or a DC charger is used. In particular, in the case of a DC charger, a scorotron charger with a grid that can control the charging potential is preferable to a corotron charger with only a charging wire, and the charging potential is approximately the same as that at the end of the secondary charging and simultaneous image exposure process. It is preferable that there be. For example, if the voltage at the end of the secondary charging and simultaneous exposure process is approximately 0V, and the potential of the toner adhesion area is positive, the grid of the scorotron charger will be approximately 0V.
Just set it to 0V (for example, ground it) and apply a negative voltage to the charged wire. The effect of the above-mentioned charging process is that it sufficiently lowers the residual potential of the area to which toner has adhered due to the previous development and prevents other toner from adhering to the same area, as already mentioned. In addition, the effect of preventing an increase in the potential on the surface of the photoreceptor due to the dark decay of the potential of the photoconductive layer and the effect of imparting a sufficient amount of charge to the toner so that a toner image can be transferred satisfactorily later are also obtained. Regarding this, see Figure 14,
For comparison with the embodiment of the present invention described with reference to FIG.
When a three-color image was formed under the same conditions except for M, the recorded image had poor color tone.
Compared to the original image, it was very inferior. On the other hand, in the case of the above-mentioned embodiment of the present invention, not only was a recorded image with clear colors almost the same as that of the original image obtained, but the toner transfer rate was also increased, and cleaning was improved. The effect of reducing the amount of toner collected in the device 13 was also obtained. As is clear from the above, the charging process for the purpose of averaging before development is extremely important for obtaining a good multicolor image. Specifically, in the image forming apparatus shown in FIG.
The image carrier 4 consists of a photoreceptor with a layer structure shown in FIG. 4, the photoconductive layer 2 has a layer structure made of the materials shown in Table 2 below, the total thickness of the photoreceptor 2 is about 32 μm, and the transparent insulating layer 3b.
is a polyethylene film with a thickness of 20 μm, and the 12th
It includes a filter layer 3a in which l ₁ and l ₂ of the distribution of R, G, and B filter parts in the figure are both 200 μm, and the diameter is
A 200 mm image carrier 4 was rotated in the direction of the arrow at a linear velocity of 50 m/sec.

[Table] It is assumed that the image carrier 4 is irradiated with white light from the light source 5a and the surface potential of the image carrier 4 becomes -1.5 kV after being charged with the charger 5b by the corotron charger. It is assumed that the surface potential of the image carrier 4 becomes -50 V after discharging with a scorotron charger, and each developing device 8Y to 8C is equipped with a developing sleeve made of non-magnetic stainless steel and having an outer diameter of 25 mm.
It rotates to the left at a rotation speed of 153 rpm, and the internal magnet has eight magnetic poles in the circumferential direction that provide a maximum magnetic flux density of 800 G to the surface of the developing sleeve, and rotates to the right at a rotation speed of 800 rpm to form the developer layer. The image carrier 4 and each developing device 8Y are conveyed by a magnetic brush developing device.
The surface gap with the developing sleeve of 8C is 1 mm, and each developing device 8Y to 8C is loaded with toner and average particles of yellow, magenta, and cyan, each having an average particle size of 5 μm and a triboelectric charge amount of +10 to +20 μc/g. The diameter is
Using a developer mixed at a weight ratio of 1:4 with a carrier made of a resin containing dispersed magnetic material with a resistivity of 25 μm and 10 ₁₃ Ωcm or more, each developing device 8Y to 8C
The thickness of the developer layer formed on the developing sleeve of
The gap between the image carrier and the developing sleeve is set to 0.5 mm.
0.7 mm, and when each of the developing devices 8Y to 8C performs development, a developing bias consisting of a DC voltage of -100V and an AC voltage with an effective value of 1kV and a frequency of 2kHz is applied to the developing sleeve, and the chargers 9Y, Smoothing by 9M is performed under the following conditions: in the first example, a DC voltage of -50V is applied to the back plate and an AC voltage of 6 kV is applied to the charging electrode; in the second example, the back plate is grounded and the charging electrode is applied with +5 .5kV
When three color images were copied under the conditions of applying a DC voltage of -50V and a grid voltage of -50V, there was no color shift at all in either the first or second example, and the color reproduction was good. An extremely clear image was obtained. Note that the obtained potential contrast was 300 to 500 V with respect to the entire surface exposure with each specific light. All of the above explanations have been made regarding an example of a color copying machine using so-called three-color separation filters and three primary color toners, but the present invention is not limited to the illustrated example, and the number and colors of separation filters and their It goes without saying that the combination of corresponding toner colors can also be arbitrarily selected depending on the purpose. For example, processes for obtaining two-color copies are also conceivable. In addition, "electrification" in the explanation so far includes:
This also includes cases where the surface potential of the photoreceptor becomes 0 or the surface charge disappears when charging is performed. Furthermore, in the above explanation, the spectral characteristics of light for full-surface exposure can be obtained by using green (G), blue (B), and red (R) filters, but they can also be obtained by means other than filters. It may be something that can be done,
In addition, its spectral characteristics are not limited to G, B, and R; the point is that by exposing the entire surface to a specific light, it is hidden only in a specific filter section (not limited to one type) corresponding to the specific light on the photoreceptor. Any spectral characteristic that forms an image may be used. In addition, the image forming method of this embodiment forms an electrostatic latent image as follows: primary charging and simultaneous uniform exposure → secondary charging → image exposure → tertiary charging, and then a specific filter section using specific light. This includes an image forming method in which potential pattern formation and development are repeated. Furthermore, uniform exposure simultaneously with primary charging is intended to inject charges into the photosensitive layer, and can be performed separately. That is, the same effect can be produced even if uniform exposure is performed after primary charging. F. Effects of the Invention As explained above, the photoreceptor according to the present invention has a first charge generating layer, a second charge generating layer, a charge generating layer interposed between the first charge generating layer, and the second charge generating layer. It is composed of a photoconductive layer having a laminated structure consisting of a charge transfer layer in which only one of the layers is movable; an insulating layer; and a layer consisting of a plurality of types of color separation filters; The method involves forming a uniform potential on the surface of the photoreceptor by charging and uniformly exposing the photoreceptor configured as described above through a layer consisting of multiple types of color separation filters, and then generating charges on the upper layer side. After performing an imagewise exposure to irradiate the layer, the entire surface is exposed to specific light to form a potential pattern in a portion corresponding to the color separation filter;
Since it is configured to perform development, the following effects can be achieved. () Since a layer consisting of multiple types of color separation filters is used, a latent image for each color can be formed with a single image exposure, and high-quality images can be easily created at high speed without causing color shift or color turbidity. is obtained. () By configuring the photoconductive layer to consist of multiple layers as described above, charges can be generated in different charge generation layers for each process, and the movement of these charges is caused by the presence of the charge transfer layer. This facilitates the use of photoconductive layers having a laminated structure. As a result, there is a wide range of material selection for each layer that makes up the photoreceptor, and there are fewer design restrictions.In addition, the charge retention ability of the photoconductive layer can be increased, and the spectral sensitivity distribution can be increased and balanced. It can be easily taken and a higher quality image can be formed.

[Brief explanation of the drawing]

1 to 5 and 11 to 19 show embodiments of the present invention, and FIGS. 6 to 10 show reference examples. Figure, 4th
Figures 5, 6, 7, 8, 9 and 10 are cross-sectional views of the photoreceptor, Figures 11 and 12.
Figures 1 and 13 are plan views of color separation filters,
Figure 4 is a schematic diagram of the image forming device, Figure 15 is a diagram of 1, 2, 3.
1, 2, 3, 4, 5, 6, 7, and 8 are process flow diagrams showing the image forming steps, and FIG. 17 is a time-series diagram showing how the surface potential of the photoreceptor changes as the process progresses. 18 is a schematic diagram of another image forming apparatus, and FIG. 19 is a sectional view of a developing device. In addition, in the symbols shown in the drawings, 1... conductive substrate, 1-2... translucent conductive layer, 2... photoconductive layer, 2a... first charge generation layer, 2b... second charge generation layer, 2c...charge transfer layer, 2d...layer containing a charge generation substance and a charge transfer substance, 2g
...Charge generation substance, 2t...Charge transfer substance, 3...
...insulating layer, 3a...layer consisting of a color separation filter,
3b, 3c...transparent insulating layer, 4...image carrier, 5
...Charging device, 5a...Primary charger, 5b...Uniform exposure light source, 6,9Y,9M...Charging device, 7,7
B, 7G, 7R...Full surface exposure device, 8Y, 8M,
8C, 8K...developing device.

Claims (1)

[Claims] 1(A) A photoreceptor comprising a layer having a plurality of types of color separation filter portions and a photoconductive layer, the surface side of which is insulating, the photoconductive layer comprising a charge generating material. and a charge transfer layer containing a charge transfer substance, the charge transfer layer being able to transfer only either holes or electrons. using a photoreceptor in which the charge transfer layer is interposed between the first and second charge generation layers, and these layers constitute the photoconductive layer having a laminated structure; B) A uniform negative or positive surface is formed on the surface of the photoreceptor by charging from the side of the layer having the plurality of types of color separation filter portions and uniformly exposing the layer to the lower charge generation layer. (C) Then, image exposure is performed to irradiate the upper charge generation layer from the layer having the plurality of types of color separation filter portions; (D) After that, charge generation on the upper layer side is performed. An image forming method that repeats the steps of irradiating the entire surface of a layer with exposure light using specific light to form a potential pattern in a portion corresponding to the color separation filter, and performing development. 2. A photoreceptor comprising a layer having a plurality of types of color separation filter portions and a photoconductive layer, the surface side of which is insulating, the photoconductive layer comprising first and second layers containing a charge generating substance. A charge transfer layer comprising a charge generation layer and a charge transfer layer containing a charge transfer substance, the charge transfer layer being able to transfer only either holes or electrons, the charge transfer layer is interposed between the first and second charge generation layers, and these layers constitute the photoconductive layer having a laminated structure.