JPS62205363A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To eliminate unnecessary light diffusing to an adjacent filter and to obtain sufficiently good color picture image by providing a light scattering layer or a light absorbing layer. CONSTITUTION:An electrophotographic sensitive body for preparing a color picture image by once image exposure is constituted by forming a photoconductive layer 2a comprising CdS and an insulating layer 3, for forming each color filter, etc., on an electroconductive substrate 1. Further, a light absorbing layer 2b is also formed below the layer 2a. Accordingly, unnecessary light due to diffusion of reflected light into an adjacent filter from a substrate 1 which is generated by the oblique incident light when whole surface exposure is executed for the formation of latent image using transmitted light through a specified filter, is eliminated. As the result, sufficiently good color picture image is obtd. Further to say, similar result may be obtd. if a light diffusing layer is formed in place of the light absorbing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor that forms color images using electrophotography.

[Background of the invention]

Many multicolor image forming devices using electrophotography have been proposed in the past. These can generally be divided into the following categories. The first method involves sequentially repeating the formation of a color-separated electrostatic latent image on a single photoreceptor and its development, and then stacking the images on the photoreceptor or transferring the toner image to a transfer material each time it is developed. This involves layering colors on the material. The second method uses a plurality of photoreceptors corresponding to the number of colors, forms toner images of different colors on each photoreceptor at the same time, and sequentially transfers them to a transfer material to obtain a multicolor image. The latter method is advantageous in terms of high speed because toner images of each color are formed simultaneously on each photoreceptor, but it requires multiple photoreceptors, exposure means, etc., making the device complex, large, and expensive. Due to the price, it is not practical.

Furthermore, all of the multicolor image forming apparatuses described above have a major drawback in that it is difficult to align the images when overlapping colors, and color shift in images cannot be completely prevented.

In order to fundamentally solve these problems, the present inventors have previously invented an apparatus that can form a multicolor image on a photoreceptor by performing image exposure once.

The apparatus forms a multicolor image as follows using a photoreceptor provided with an insulating layer including a conductive member, a photoconductive layer, and a filter layer consisting of a plurality of different types of filters.

That is, by applying electrical charge and image exposure to the surface of the photoreceptor, an image is formed based on the charge density at the interface between the insulating layer and the photoconductive layer, and only one type of filter among the plurality of types of filters is applied to the image forming surface. A potential pattern is formed on the filter portion of the photoreceptor by exposing the entire surface to light that passes through the photoreceptor, and the potential pattern is developed by a developing device containing toner of a specific color to form a monochromatic toner image. Ru. Next, the potential is smoothed by recharging, and then the entire surface is exposed to light that passes through a different filter section than the previous one, and development is performed using a developing device that stores toner of a different color than the previous one. Second, a second color toner image is formed. Below are the necessary times of exposure and development. As a result, toners of different colors are deposited on each filter portion of the photoreceptor, forming a multicolor image.

(Patent Application No. 59-83096 and No. 59-1870114
(see issue). According to this multicolor image forming apparatus, image exposure is 1
There is no risk of color misalignment as it only takes a few seconds.

In this multicolor image device, color reproduction is performed by a so-called additive color method in which colors are not superimposed at the same position in principle.

Therefore, in addition to solving the above-mentioned color misregistration problem, the fidelity of color reproduction is high.

The present inventors have proposed the above and Japanese Patent Application Nos. 59-83096 and 59-83096.
An application has already been filed for an image forming apparatus which retains the advantages of the invention according to No. 9-1.87044 and further enables the formation of an image in which the color of the original image is changed to a desired color. First, the image forming apparatus will be explained.

5 to 9, FIG. 13, and FIG. 14 are sectional views schematically showing the structure of an image carrier (photoreceptor) used in the multicolor image forming apparatus of the present invention, and FIGS. 10 to 12, respectively. 1 is a plan view showing arrangement rows of a plurality of types of filters in an insulating layer of a photoconductor, FIGS. 1 and 17 are schematic diagrams showing the configuration of an example of a multicolor image forming apparatus according to the present invention, and FIG. FIG. 16 is a process diagram showing the state in which image formation is delayed in a color image forming apparatus, FIG. This is a section showing an example of a developing device used in a multicolor image forming apparatus.

In Figures 5 to 8, ■ is a conductive material formed into a cylindrical or endless belt ring using metals such as aluminum, iron, nickel, copper, etc. or their alloys in an appropriate shape and structure as required. 2 is a photoconductor such as sulfur, selenium, amorphous silicon or an alloy containing sulfur, selenium, tellurium, arsenic, antimony, etc., or oxidation of metals such as zinc, aluminum, antimony, bismuth, cadmium, molybdenum, etc. Inorganic photoconductors such as iodides, sulfides, selenides, azo-based, disazo-based, trisazo-based, phthalocyanine-based dyes and pigments, vinyl carbazole, trinitrofluorenone, polyvinyl carbazole, ogizadiazole, hydrazone compounds, sudirbene derivatives, Organic photoconductive materials in which a charge transport substance such as a styryl derivative is dispersed in an insulating binder resin such as polyethylene, polyester, polypropylene, borisdylene, polyvinyl chloride, polyvinyl acetate, polycarbonate, acrylic resin, silicone resin, fluororesin, or Epoquine resin. The functionally separated photoconductive layer L3 consists of a photoconductive layer consisting of a charge generation layer and a charge transfer layer, and is composed of red (R), green (G), Blue (B)
This is an insulating layer including a layer 3a made of color separation filters such as . The insulating layer 3 in the photoreceptor shown in FIG. 5 is formed by printing, vapor deposition, photoresist, or other means on the photoconductive layer 2 by printing, vapor depositing, photoresist, etc., on the photoconductive layer 2 with an insulating material such as a resin colored with a coloring agent that forms a color separation filter. The insulating layer 3 in the photoreceptor shown in FIG. 6 is formed by depositing a filter layer 3a in a predetermined pattern (=7) on the surface of a transparent insulating layer 3b formed by conventional known means. formed,
The insulating layer 3 in the photoreceptor shown in FIG. 7 is formed by sandwiching a filter layer 3a between transparent insulating layers 3b, and the insulating layer 3 in the photoreceptor shown in FIG. A transparent insulation layer 1m3b is formed on the outside thereof. These filter layers 3a are formed by printing, vapor deposition, photoresist, or other means.

The insulating layer 3 may be formed by first forming an insulating film or sheet containing the filter layer 3a, and then attaching or adhering it to the photoconductive layer 2'' by an appropriate means.

In addition, as shown in FIG. 9, for example, in the case of a drum-shaped light body, a transparent insulating layer 3b is provided on the photoconductive layer 2'', and R, G, and T3 filters are provided on the transparent insulating layer 3b with a minute gap md thereon. It is also possible to provide a layer 3-2 (similar to the layer 3a) coaxially. That is, a cylindrical body 3-2 consisting of R, G, and B filters is coaxially fitted onto a drum-shaped photoreceptor having no filter, with a minute gap md left therebetween. With such a structure, any one of the filter layers having the structures shown in FIGS. 10, 11, and 12 (details will be described later) can be selected, replaced, and used. However, the gap md should not be too large so that the image of the filter cell is not extremely blurred and projected onto the insulating layer and the photoconductive layer. Further, the transparent insulating layer 3b and the filter layer 3-2 are not completely separated from each other, and may be in contact with each other.

Due to the adhesion of colorants, colored resins, etc. on the insulating layer 3.
) The filter layer 3a formed of R, G.

There are no particular restrictions on the shape or arrangement of minute filters such as B, but for easy pattern formation, striped distribution as shown in Figure 10, or reproduction of delicate multicolor images. A mosaic distribution as shown in FIGS. 11 and 12 is preferable in that the distribution is carried out in a manner similar to that shown in FIGS. R, G, B
The direction in which these filters are arranged may be in any direction in the spreading direction of the photoreceptor, including those with a mosaic distribution as well as those with a stripe distribution. For example, in the case of a rotating drum-shaped photoreceptor, the periodic direction in the mosaic or stripe diagram may be parallel to, perpendicular to, or oblique to the axis of the photoreceptor. R,G
, B, etc., if the size of the filter becomes too large, the resolution and color reproducibility of the image will decrease, resulting in deterioration of the image quality.On the other hand, if the size of the filter becomes too small, the size will be the same as or smaller than the particle size of the toner particles. In this case, it becomes easy to be influenced by other adjacent color parts, and it becomes difficult to form a distribution pattern of the filter. Therefore, each filter part has a width of 10 to 500 μm as shown by ρ in the figure, or The size is preferable.

Note that each filter preferably has high resistance. Particularly preferably, it is 1013 Ωcm or more.

If the resistance is low, they can be electrically insulated from each other by providing a gap or by interposing a rim.

The layer 3a made of the color separation filter as described above is not provided,
A photoreceptor whose photoconductive layer is provided with a color separation function can also be used. Figures 13 and 14 were previously proposed by the applicant (Japanese Patent Application No. 59-201085, 60-2451,
No. 77) An example of a photoreceptor is shown. The photoreceptor shown in FIG. 13 has a conductive substrate 1 and a photoconductive portion 2 having a desired spectral sensitivity distribution
R, 2G, 2B, such as red (R), green (G), blue (
In B), a photoconductive layer 2-2 including a large number of sensitive photoconductive parts is provided, and a transparent insulating layer 3b is provided thereon.

The photoreceptor shown in FIG. 14 has a charge transfer layer 2-2 on a conductive substrate I.
3b, and a portion 2 with different spectral sensitivity distribution is provided thereon.
A charge generation layer 2-3a consisting of B, 2R, and 2G is provided,
Further, a transparent insulating layer 3b is provided thereon.

In the photoreceptor shown in FIG. 14, a photoconductive layer 2-3 is constituted by a charge generation layer 2-3a and a charge transfer layer 2-3b.

Photoconductive layer 2-2 in FIG. 13 and charge generation layer 2 in FIG. 14
The planar structure of -3a may be the same planar structure as shown in FIG. 10, FIG. 11, or FIG. 12, similar to the insulating layer made of the color separation filter described above.

First, an original image (original image) is placed on the photoreceptor with the above configuration.
The principle of forming a multicolor image of the same color as the image will be explained with reference to FIG. Note that FIG. 15 shows an example in which an n-type semiconductor photoconductor such as cadmium sulfide is used for the photoconductive layer 2 of the photoreceptor;
The same reference numerals as those in the figures to FIG. 8 indicate the same functional members.

FIG. 15 [1] shows a state in which the photoreceptor 4 is uniformly charged by positive corona discharge from the charger 5, and positive charges are generated on the surface of the insulating layer 3, and correspondingly, the photoconductive layer A negative charge is induced at the interface between photoreceptor 2 and insulating layer 3, and as a result, the surface of photoreceptor 4 exhibits a uniform potential as seen in the graph of potential E.

FIG. 15 [2] shows, as an example, a change in the charged surface in a portion irradiated with the red image LR in a state where the above-mentioned charged surface has been subjected to image exposure by the image exposure device 6.

The red image L R passes through the R filter part of the insulating layer 3 and makes the part of the photoconductive layer 2 below it conductive. Negative charges at the interface between the conductive layer 2 and the insulating layer 3 disappear. Furthermore, the potential pattern is sufficiently smoothed by the charger 26. On the other hand, the G1B filter part has a red image L,
Since the light does not pass through the photoconductive layer 2, the negative charges of the photoconductive layer 2 remain in that portion. The same applies to other color components of image exposure. In this way, a latent image is formed on the interface between the insulating layer 3 and the photoconductive layer 2 due to the charge density corresponding to the color component of each filter. However, the charger 16 of the image exposure device 6
Due to the action of the charger 26, the surface potential of the photoreceptor becomes equal to the potential E regardless of the amount of charge on the interface between the insulating layer 3 and the photoconductive layer 2, that is, regardless of whether or not imagewise exposure is applied. It becomes constant as shown in the graph. The green component and the blue component of image exposure give similar results, and the state in which they are integrated is the state in which image exposure has been performed by the image exposure device 6, and as it is, it does not function as an electrostatic image.

FIG. 15 [3] shows a state in which the above-mentioned image exposure surface is uniformly exposed to blue light La from the lamp 7B. The blue light LB does not pass through the R and G filter parts, so it does not change those parts, but it passes through the B filter part and makes the photoconductive layer 2 below it conductive, thereby reducing the light in that part. The charges at the upper and lower interfaces of the conductive layer 2 are neutralized, and as a result, in the B filter portion, a potential pattern appears on the surface of the insulating layer 3 as shown in the graph, giving a complementary color image of blue in the previous image exposure.

FIG. 15 [4] shows a state in which a potential pattern formed by full-surface exposure with blue light LB is developed by a developing device 8Y containing negatively charged yellow toner TY. The yellow toner TY adheres only to the B filter portion where the potential has changed due to the entire surface exposure process, and does not adhere to the R and G filter portions where the potential has not changed. As a result, a color-separated one-color yellow toner image is formed on the surface of the photoreceptor 4. Although the potential of the part of the B filter to which the yellow toner TY is attached is somewhat lowered by development, the surface potential is not uniform as shown in the graph.

FIG. 15 [5] shows a state in which corona discharge is performed by the charger 9Y on the surface of the photoreceptor 4 on which a yellow toner image is formed. This discharge by the charger 9Y lowers the potential of the B filter portion to which the yellow toner TY is attached, and makes the surface potential uniform. The surface potential of this photoreceptor 4 is shown in a graph.

Subsequently, this yellow toner image is formed as shown in FIG.
5], the entire surface of the photoreceptor 4 is exposed to green light obtained from a lamp. As a result, a potential pattern appears in the G filter portion, similar to that described in FIG. 15 [3]. When this potential pattern is developed by a developing device containing magenta toner, the magenta toner becomes G
A magenta toner image is formed by adhering only to the filter portion, similar to FIG. 15 [4]. As a result, two-color toner images are formed on the photoreceptor. Further, a corona discharge is applied to this image forming surface using a charger in the same manner as shown in FIG. 15 [5] to make the surface potential uniform. These processes are shown in Figure 15 [
6], [7], and [8].

Subsequently, when the surface of the photoreceptor 4 on which the two-color toner images have been formed is entirely exposed to red light obtained by a lamp,
Also, as described in Fig. 15 [3], a potential pattern appears in the R filter portion, and a cyan toner image is formed by developing this potential pattern with a developing device that stores cyan toner. However, in this case, since it is a red image, no potential pattern is formed and cyan toner does not adhere. In this way, a red image is reproduced from yellow toner and magenta toner.

As a result of completing the above steps, a clear three-color image without color shift or color turbidity is formed on the photoreceptor 4.

Yellow using the three-color separation method performed as described above.
Reproduction of original images using magenta and cyan toners is summarized in Table 1 below. In Table 1, the symbol "・S" means that an image pattern of charge density is formed at the interface between the insulating layer 3 and the photoconductive layer 2 of the photoreceptor, and the symbol "○" means that an image-like potential pattern appears on the surface of the photoreceptor. The symbol "O" indicates that a toner image is formed, the symbol "↓" indicates that the state in the upper column is maintained, and the blank indicates that no image exists.
It shows. Further, "-" in the "A" attached toner column indicates that no toner is attached, and Y, M, and C indicate that yellow toner, magenta toner, and cyan toner are attached, respectively.

A black image is reproduced from Y, M, and C toner deposited on each filter. In principle, this process is additive color mixing, but in reality, the toner is spread during the development, transfer, separation, and fixing steps, so subtractive color mixing occurs, and high image density and good black images are reproduced.

Furthermore, FIG. 16 shows each filter portion B, G, H of the photoreceptor.
5.16.26.7B on the horizontal axis shows a situation where the surface potential at
, 8Y, 9Y, 7G, 8M, 9M, 7R.

8C indicates a step in which members with the same reference numerals as those in FIG. 1 or FIG. 15 act on the photoreceptor 4, and B.

G shows potentials corresponding to the black background and white background of the document caused by full-surface exposure. (For example between the above processes -
The interval between the next charging and the secondary charging, the interval between the entire surface exposure and development, etc. are omitted. ) Although FIG. 15 shows an example in which the photoconductive layer 2 of the photoreceptor 4 is made of an n-type photosemiconductor, even if the photoconductive layer 2 is made of a p-type photosemiconductor such as selenium, the charge The basic image formation process does not change except that the positive and negative signs are reversed during the operation. Furthermore, if it is difficult to inject charges when charging the photoreceptor 4, uniform irradiation with light may be used at the same time as charging or before or after charging.

As can be seen from Figure 15 and Table 1, in order to reproduce the colors of the original using this image forming method, a potential pattern must be formed in the color separation filter portion that does not transmit the color components of the light from the original. The latent image is developed using three primary color toners to reproduce color. Therefore, color conversion is possible by selecting a combination of exposure light for full-surface exposure and development to form the potential pattern.

Next, an example of obtaining monochrome (monocolor is black and white) from a full-color original drawing will be explained with reference to Tables 2, 3, and 4 below. In both cases, the entire surface is exposed continuously (
In Table 4, the entire surface was exposed only once), and then development was performed.

Table 2 shows yellow, magenta,
An example of obtaining a monochrome image of either cyan or black and white will be shown. In this example, three types of full-surface exposure are performed in succession, and one type of toner is attached to all color separation filter parts using one selected developing device to obtain the above-mentioned monochrome or black and white image. This is an example.

Table 3 shows examples of obtaining monochrome red, blue, green, or black and white images from full-color originals. In this example, three types of full-surface exposure are performed in succession, and the selected two
This is an example in which two types of toner are attached to all the color separation filter portions using one developing device to obtain the above-mentioned monocolor or black and white image.

Table 4 shows how to remove a specific color from a full-color original image (in this example, the red part of the original image is converted to white by removing red).
, an example of obtaining a monochrome image of red, blue, or green, or a monochrome image will be shown.

After image exposure, the entire surface of the color to be removed (red in this example) is exposed, and then two types of toner are attached to one type of color separation filter (R filter in this example) using two selected developing devices. , to obtain the above-mentioned monochrome or black-and-white image without a specific color (red in this example).

When obtaining a monochrome image of yellow, magenta, or cyan without a specific color, it is sufficient to use one developing device corresponding to the color.

When removing a specific color, toner is deposited only on the portion of one type of color separation filter that transmits the exposure light during full-surface exposure, so the amount of toner deposited tends to be insufficient and the color tends to be pale. Therefore, during development, lower the voltage of the DC component of the developing bias described later, increase the voltage of the AC component, or lower the frequency of the AC component, etc.
It is desirable to increase the toner image density.

As described below, in order to obtain a monochrome image, it is not necessary to prepare a dedicated development device for monochrome development, but by selecting and using an appropriate development device from among the development devices for full color development, it is possible to create an image. It can form monochrome images of yellow, magenta, cyan, red, blue, and green with excellent density and resolution.

The multicolor image forming apparatus shown in FIG. 1 performs image formation based on the above principle, and the drum-shaped photoreceptor 4 is rotated once in the direction of the arrow.
During rotation, a multicolor image is formed as follows. That is, a charger 5 charges the surface of the photoreceptor 4 to a uniform potential, and an image exposure device 6 performs image exposure on the charged surface using reflected light from a white irradiation original document using a halogen light source while performing alternating current or charging. The surface potential of the photoreceptor 4 is made approximately uniform by the action of a charger 16 which performs DC corona discharge of opposite sign to that of the charger 5. Subsequently, a charger 26 similar to the charger 16 is used to completely flatten the surface potential of the photoreceptor 4. In addition, charger 2
6 may be provided adjacent to and downstream of the charger 16 of the image exposure device 6, and both may be integrated.

Next, the image-exposed surface is uniformly irradiated with blue lights T and B obtained by the lamp 7B, whereby a potential pattern that provides a red complementary color image appears on the image-exposed surface. This is developed by a developing device 8Y that stores yellow toner.

Next, a charger 9Y performs corona discharge similar to the discharger 16.
This action makes the surface potential of the photoreceptor 4 uniform.

Next, the green light obtained by the lamp 7G is uniformly irradiated to form a potential pattern that provides a complementary color image of green, and the developing device 8M that stores magenta toner develops the image, forming a two-color toner image on the surface of the photoreceptor 4. It is formed.

Similarly, the discharge of the charger 9M- similar to the charger 9Y,
Uniform irradiation with red light obtained by the lamp 7R and development by the developing device 8C containing cyan toner are performed. Through the above steps, yellow, magenta,
A superimposed image of three color toner images is formed.

In order to sharpen the image, the lamp 7K applies exposure to white light, infrared light, red light, or green light and red light to the color separation filter part that has already been contaminated with toner, and the potential pattern that is slightly generated is If the potential portion of each color separation filter portion is developed with black toner using the developing device 8K, an even better image is often obtained. The reason why blue light is not used in the above exposure is to prevent black toner from adhering to the brightest yellow toner, thereby promoting color blurring.

The multicolor toner image formed as described above passes through the developing device 8 containing black toner, which is placed in an inactive state, without being developed, and is charged by the pre-transfer charger 14. It becomes easier to transfer, and is transferred by the transfer device 10 onto the recording paper p fed from the paper feeder 15. The recording paper p onto which the multicolor toner image has been transferred is separated from the photoreceptor 4 by a separator 11, and transferred to the fixing device 1 by a conveying means 16.
7, the multicolor toner image is fixed thereon, and the paper is discharged finely.

The surface of the photoreceptor 4 to which the multicolor toner image has been transferred is neutralized by a static eliminator I2 that performs exposure and discharge, residual toner is removed by a cleaning device 13, and the state returns to the state where the next image formation can be performed again.

In the multicolor image forming apparatus shown in FIG. 1, a monochrome image is formed as follows. That is, lamps 7G, 7R, 7K
Similarly to the case of multicolor image formation with the chargers 9Y, 9M, and 9C inactive, charging by the charger 5 and charging by the charger 16 are performed.
, the entire surface is exposed using white light by discharge and image exposure by the charger 26 and simultaneous exposure of blue, green, and red by the lamp 7B.

As a result, a potential pattern appears on the entire surface of the photoreceptor 4. This is developed by one or more of the developing devices 8Y to 8 to obtain a monochrome toner image. Thereafter, as in the case of multicolor image formation, the formed monochrome toner image is transferred and fixed onto the recording paper p,
The surface of the photoreceptor 4 to which the monochromatic toner image has been transferred is cleaned. For example, to obtain a red monochrome image, the developing device 8Y
and 8M are used for overlapping development.

In the multicolor image forming process described above, each entire surface exposure does not necessarily have to be B, G, and R light. In other words, in the filter section where the entire surface of the photoreceptor has already been exposed, the charge at the interface between the insulating layer and the photoconductive layer has already disappeared, so even if light passes through it again, there will be only a slight change in the surface potential. be. Therefore, for example, full-surface exposure can be changed to red light, yellow light,
Even if development is carried out in the order of white light and correspondingly in the order of cyan toner, magenta toner, and yellow toner, a multicolor image with good color reproduction of the document can be obtained. Of course, the exposure is not limited to this, and the entire surface may be exposed with light having other spectral distributions. As mentioned above, when the light from the entire surface exposure passes through a part of the filter on the photoreceptor twice or more, the light should be It is desirable to irradiate. In this way, the light for full-surface exposure forms a potential pattern only on the corresponding specific type of filter. (Special application 1984
(No. 198171) As described above, according to the multicolor image forming apparatus filed prior to the present invention, not only a multicolor image without color shift can be obtained, but also a monochrome image with excellent image density and resolution. can be formed.

The multicolor image forming apparatus shown in FIG. 17 has one rotation of the photoreceptor 4.
This image forming apparatus differs from the image forming apparatus shown in FIG. 1 in that a colored toner image is formed.

Note that the full-surface exposure apparatus shown in FIGS. 1 and 17 includes the 18th
As shown in the figure, filters FB and FG are used by switching the white light source 7I2 and the shutter 7S.

The entire surface may be exposed to light of a specific color selected by a full surface exposure lamp 7 having a PR.

Similar to the multicolor image forming apparatus shown in FIG. 1, this multicolor image forming apparatus performs the same image forming operation as described in FIG. 15 and Table 1, and produces multicolor images without color shift. A monochromatic image with excellent image density and resolution can be formed. That is,
For example, when forming a three-color image, the photoreceptor 4 is charged by the charger 5, image exposure is performed by the charger 16, and the surface potential is made uniform.
The entire surface is exposed with the light that has passed through the blue filter FB,
The developing device 8Y develops the potential pattern thus formed to form a yellow toner image.

This tonneau image is transferred to the developing devices 8M, 8G, 8, a pre-transfer charger 14, a transfer device 10, a separator 11, and a cleaning device 1.
3 and the charger 5 without being affected.

When the photoreceptor 4 on which the toner image has been formed reaches the position of the charger 16, it is not irradiated with light and receives only a corona discharge (thus, the surface potential becomes uniform, which is obtained by the lamp 7 and the green filter PG). The entire surface is exposed to light to form a potential pattern.Next, this is developed by the J developing device 8M to form a magenta toner image.Similarly, the potential pattern is developed by light transmitted through the red filter F. Formation and development by the developing device 8C are performed to obtain a three-color toner image.

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. It has the advantage of being cost-effective.

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. 1 and 17.

The developing device shown in FIG. 19 includes a developing sleeve 81 and a magnet body 82 having N and S magnetic poles on the inner peripheral surface of the developing sleeve 81.
At least one of them rotates, and the magnetic force of the magnet body 82 transports the developer attracted to the surface of the developing sleeve 81 from the developer reservoir 83 in the direction of the arrow. During the conveyance of the developer, the amount of conveyance is regulated by the layer thickness regulation plate 84 to form a developer layer, and the developer layer forms a potential pattern of the photoconductor 4 in the developing area where the developing sleeve 81 faces the photoconductor 4. Develop according to the instructions. During development, a developing bias voltage is applied to the developing sleeve 81 by a bias power supply 80 . Furthermore, even if development is not performed as necessary, toner may migrate from the developing sleeve 81 to the photoreceptor 4,
A bias voltage may be applied to the developing sleeve 81 in order to prevent the toner from transferring from the photoreceptor 4 to the developing sleeve 81.

That is, while only the yellow toner developer is operated and the electrostatic image is developed by the developer 8Y, the other developers 8M, 8C, 8, etc. shown in FIGS. 1 and 17 are operated. was kept undeveloped. This can be done by separating the developing sleeve 81 from the bias power supply 80 and leaving it in a floating state or by grounding it, or by actively applying only a DC bias voltage of the same polarity or opposite polarity to the toner charging to the developing sleeve 81. Among these, it is preferable to apply a DC bias voltage of opposite polarity to that of the toner. Developer 8M, 8C.

=30= Since development is performed under the same non-contact jumping development conditions as in the developing device, the developer layer on the developing sleeve 81 does not need to be particularly removed. Further, a developing device that is not in use may be stopped.

Of course, it is also effective to remove the developer from the sleeve by separating the developing device from the photoreceptor. 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. A means 88 is a toner replenishing roller that replenishes 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, that is, the surface of the photoreceptor is directly rubbed with a magnetic brush, but especially after the second development, the developer layer is A developing method that does not contact the photoreceptor surface, such as U.S. Pat. No. 3,893,418,
Japanese Unexamined Patent Publication No. 18656/1983, especially Japanese Patent Application No. 58/57
No. 446, Japanese Patent Application No. 1982-238295, Japanese Patent Application No. 1983-
No. 238296, and for superposition on the same latent image, Japanese Patent Application No. 58-139974, No. 59-1.399
It is preferable to use the method described in each specification of No. 75. These methods use a one-component or two-component developer containing a non-magnetic toner whose coloring can be freely selected, create an alternating electric field in the development area, and perform development without contact between the electrostatic image support and the developer layer. It is something to do. 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 Development is performed under various conditions as described above.

The color toner used for development is made using known techniques and consists of known binding resins, organic and inorganic pigments, various chromatic and achromatic colorants such as dyes, and various magnetic additives that are commonly used in toners. Toner for electrostatic development can be used, and as a carrier, iron powder, ferrite powder, which are usually used for electrostatic images, magnetic materials such as those coated with resin or magnetic materials dispersed in resin can be used. Various known carriers such as carriers can be used.

In addition, the applicant filed the patent application No. 58-24966 earlier.
The developing method described in No. 9 and No. 240066 may be used [Problems to be Solved by the Invention] 1. In the multicolor image forming apparatus, image exposure and full-surface exposure light are applied to the photoreceptor. It has not only vertical light but also obliquely incident light. Since the photoreceptor generally has a light-transmitting property, the light incident obliquely enters the photosensitive layer of the other filter part through the path shown in FIGS. 2 and 3, and the photosensitive layer is Release the accumulated charge.

This causes the color balance to deteriorate, resulting in poor color reproducibility.
If it becomes severe, the resolution of the image will be reduced.

The present invention has been made in view of the above points, and its purpose is to provide an electrophotographic photoreceptor that can remove unnecessary light that diffuses to adjacent filters and obtain high-quality images. There is a particular thing.

[Means for solving problems]

The above object is achieved by an electrophotographic photoreceptor having a surface insulating layer and an in-plane color separation function, which is characterized by having a light-scattering or light-absorbing layer.

[For production]

The paths in which the light incident on the photoreceptor becomes unnecessary light and diffuses into the adjacent filter section are caused by light incident obliquely on the photosensitive layer as shown in Figure 2, and by incident light as shown in Figure 3. The cause is thought to be light that has once been reflected by a conductive substrate.

In general, long-wavelength light has good permeability to the photoreceptor and easily reaches the deep part of the photosensitive layer, so it tends to become unnecessary light as shown in FIGS. 2 and 3. For example, in an organic photoreceptor having a charge generation layer and a charge transfer layer, the charge generation layer has a thickness of 0.5 to 5 μm.
Because it is formed so thin, a small amount of light of all wavelengths in the visible range passes through the charge generation layer. Also, Se, Te, S
Se sensitized by b, etc., CdS sensitized by Cu or Se.

For the photosensitive element 34, which is not sufficiently sensitive to long wavelength light such as Si, strong red light is irradiated to cause a certain potential change in the blue, green, and red color separation filter sections.

Generally, a photosensitive layer has good transmittance for light having a wavelength with low sensitivity, so the long wavelength light having low sensitivity as described above particularly enters into the interior from the surface of the photosensitive layer. The following methods can be considered to prevent the incident light that has entered the inside of the photosensitive layer from diffusing into the adjacent filter section as described above.

(A) Processing in a photosensitive layer (A-1) Absorbing light (A-2) Scattering light (B) Processing on a conductive substrate (B-1) Absorbing light (B-2 ) As method (A-1) for scattering light, a light absorbing agent is placed in the photosensitive layer.

In the photoreceptor having the structure shown in FIG. 4, when the charge generation layer 2a easily transmits red light, a dye and pigment that absorbs red light is mixed as a light absorbing agent into the charge transfer layer 2b to absorb the light.

In method (A-2), a light scattering agent is added to the photosensitive layer. For example, fine particles of a white pigment such as titanium oxide or zinc oxide are suspended in the photosensitive layer as a light scattering agent to scatter incident light.

In addition, in a uniformly dispersed photoreceptor such as CdS, (A-1) and (
A-2) is used in conjunction with the photosensitive layer as shown in Figure 4.
The first layer 2a is a layer made of a mixture of CdS and a binder, and the lower layer 2h is a layer made of a mixture of CdS, a light absorber, a light scattering agent, and a binder to absorb light and prevent light diffusion.

In method (13-1), a layer containing a light absorbing agent is provided on a conductive substrate to absorb light. It is also effective to mix a light-absorbing agent into the conductive substrate, and the conductive substrate can also be made by mixing a material that has both conductivity and light-absorbing properties, such as conductive carbon, with a binder. .

In the case of Sc photoreceptor, Te
It is also possible to provide a conductive substrate.

Alternatively, as shown in Japanese Patent Application No. 60-245178, a structure including an insulating layer having a conductive substrate, a charge generation layer, a charge transfer layer, a charge generation layer, and a filter layer is used to generate charges on the conductive substrate. It is also possible to construct the layer with a material that absorbs 70% of the light.

As method (B-2), in addition to providing a layer containing a light scattering agent mixed in the conductive substrate as described in (A-2), it is also effective to mix a light scattering agent into the conductive substrate. be. Further, light scattering can also be performed by forming minute irregularities (surface roughness of 5S or less) on the surface of the conductive substrate.

〔Example〕

(Example 1) The photoreceptor 4 in the multicolor image forming apparatus shown in FIG. There is a photoconductive layer made of 5e-Te (Te 20%) with a thickness of 40 μm, and R and G layers as shown in FIG.
, B consists of a mosaic arrangement of filter parts, each filter has a length a of 11007z and an insulating layer with a thickness of 20 μm, an outer diameter of 80 nm and a surface speed of 100 mm.
It is assumed that the rotation speed is /sec.

Developing devices 8Y, 8M, 8C, 8Kl: The developing devices having the structure shown in FIG. 19 were used. The developing sleeve 81 is made of non-magnetic stainless steel, has an outer diameter of 20 mm, and rotates in the direction of the arrow at a surface speed of 50 mm/sec during development.

The magnet body 82 has 8 N and S magnetic poles and provides a maximum magnetic flux density of 800 G to the surface of the developing sleeve 81, and during development,
．． Rotate in the direction of the arrow at 00 rpm. The surface gap between the photoreceptor 4 and the developing sleeve 81 is determined by each developing device 8Y, 8M, 8C.
, 8K, and 0.75 mm, so that a developer layer with a thickness of 0.5 mm was formed on the developing sleeve 81. The developer has an average particle size of 10μm and has a rating of +10 to +30.
A toner triboelectrically charged to .mu.c/g and a carrier made of a resin containing a dispersed magnetic material having an average particle diameter of 2571 m and a resistivity of 10'3 Ωcm or more were mixed at a weight ratio of 19. Each developing device has a toner color of 8Y.

Of course, 8M, 8C, and 8 are different from yellow, magenta, cyan, and black.

A corotron discharger is used as charger 5, and charger 16.2
8.9Y, 9M, and 9c D all used a scorotron discharger. Then, a discharge voltage that makes the surface potential of the photoreceptor 4 -1.5 KV is applied to the charger 5, and a surface potential of + is applied to the discharger 61 and the chargers 9Y and 9M.
A discharge voltage of 150V was applied.

When the developing devices 8Y, 8M, and 8C each perform development, a developing bias voltage consisting of a DC voltage of +100 V and an AC voltage with an effective value of 1.5 KV and a frequency of 2 KHz is applied to the developing sleeve 81. , developing device 8K
When performing development, the developing sleeve 81 is supplied with a DC voltage of +100 cm, an effective value of 1.2 KV, and a frequency of 2 KHz.
A developing bias voltage consisting of a superposition of alternating current voltages was applied.

At this time, the potential contrast generated by exposing the entire color separation function section to the specific light of each B, G, and R was 200 to 40.
It was 0V.

When an image was formed under the above conditions as described in Table 1, a three-color image with good color tone and an image with excellent resolution and high image density and contrast were obtained without color shift. In addition, in the formation of the monochromatic images shown in Tables 2 to 4, the developing conditions were changed to 2.5 KV only for the AC voltage, since sufficient image density was not obtained under the same conditions for the image formation in Table 4.
By changing the settings to , a monochrome image similar to the above was obtained.

(Example 2) A Te layer of 2 to 4μ on a conductive substrate made of aluminum
5e-Te (T e2
5%) was used as a photosensitive layer.

Blue light and green light are absorbed in the surface layer of the 5e-Te layer, red light is absorbed in the Te layer, and the Te layer also serves as a charge injection layer because of its low electrical resistance. A filter layer similar to that in Example 1 was provided on this photosensitive layer to prepare a photoreceptor.

An image was formed in the same manner as in Example 1 using the photoreceptor described above in the multicolor image forming apparatus shown in FIG. 1, and a good image was obtained.

(Example 3) 100 parts by weight of conductive carbon as a charge injection layer and a light absorption layer on a polyester film (thickness 100 μm),
A mixture of 30 parts by weight of polyvinyl butyral and 1.15 parts by weight of methyl methacrylate is applied to a thickness of 511 m.

On the second layer, a mixture of 100 parts by weight of a charge transport substance containing a hydrazone compound and 150 parts by weight of polycarbonate is applied to a thickness of 25 μm as a charge transport layer.

Furthermore, as a charge generation layer, 100 parts by weight of a charge generation material containing a disazo compound and 10 parts by weight of polyvinyl butyral are formed.
A mixture of 0 parts by weight and 50 parts by weight of methyl methacrylate is applied to a thickness of 3 μm. A filter layer was provided on the thus formed photosensitive layer in the same manner as in Example 1 to prepare a photoreceptor.

As a result of forming an image in the same manner as in Example 1 using the photoreceptor described above in the multicolor image forming apparatus shown in FIG. 1, a good image could be obtained.

The charge-generating substance and the charge-transfer substance were as follows: Charge-transfer substance: C7+15 (Example 4) In the charge-transfer layer of Example 3, 10% by weight of titanium oxide fine particles, which is a white pigment, was added as a light-scattering substance. The added one was used. A filter layer was provided on the thus formed photosensitive layer in the same manner as in Example 1 to obtain a photoreceptor. Then, image formation was carried out in the same manner as in Example 1 using the above-mentioned photoreceptor in the multicolor image forming apparatus shown in FIG. 1, and as a result, a good image could be obtained.

(Example 5) In the charge transfer layer of Example 3, 10 parts by weight of copper phthalocyanine, which is a cyan dye and pigment that mainly absorbs red light, or a sulfonamide derivative was used as a light absorbing substance. A filter layer was provided on the thus formed photosensitive layer in the same manner as in Example 1 to obtain a photoreceptor.

Then, image formation was carried out in the same manner as in Example 1 using the photoreceptor No. 1 in the multicolor image forming apparatus shown in FIG. 1, and as a result, a good image could be obtained as in the above example.

The above examples are all examples of regular image forming methods, but the present invention is capable of forming color images (specially The present invention is also applicable to Japanese Patent Application No. 59-201084.59-
201085.60-245177.59-18704
Needless to say, the present invention can be similarly applied to a photoreceptor having a color separation function as shown in No. 5 and a reversal image forming method.

〔Effect of the invention〕

As explained below, by using the electrophotographic photoreceptor according to the present invention, a photoreceptor is provided in which unnecessary light is removed from the photosensitive layer and the harmful effects of unnecessary light are eliminated,
This has the effect of significantly improving the color reproducibility and resolution of images obtained by a multicolor image forming apparatus using the above photoreceptor.

[Brief explanation of drawings]

Figure 1 is a schematic front view of the inside of the image forming device, Figure 2 is an illustration of how obliquely incident light directly enters as unnecessary light, and Figure 3 is an illustration of the light incident on the photosensitive layer being reflected on the top surface of the substrate and becoming unnecessary. Figure 4 shows the path of light; Figure 4 is a cross-sectional view of a photoreceptor containing a light absorber and other substances under the CdS layer; Figures 5, 6, 7, 8, 9, and 13 and 14 are cross-sectional views of the photoconductor, FIGS. 10, 11, and 12 are plan views of the photoconductor, FIG. 15 is a process 70 diagram for explaining the image forming process, and FIG. 16 The figure is a graph showing changes in the photoreceptor surface potential during the image forming process, Figure 17 is a schematic front view of the inside of another image forming device, Figure 18 is a cross-sectional view of the entire surface exposure device, and Figure 19 is a cross-sectional view of the developing device. Figure, is. In addition, in the reference numerals shown in the drawings, 1... Conductive substrate 2... Photoconductive layer 3... Insulating layer 3a... Filter layer B... Blue color separation filter G... Green color separation filter R... Red color separation M filter 4... Photoreceptor 5, 1.6.26.9 Y, 9 M, 9 C...
Charger 6...Image exposure device 7.7 B, 7G, 7 R...Full surface exposure device pH, F
G, PR...Filter 8 Y, 8 M, 8 G, 8 K・%fi image device 3
0. It is an operation panel. Applicant: Konishiroku Photo Industry Co., Ltd.

Claims (2)

[Claims] (1) An electrophotographic photoreceptor having a surface insulating layer and an in-plane color separation function, which is characterized by having a light scattering or light absorption layer. (2) The electrophotographic photoreceptor according to claim 1, wherein the light scattering or light absorption layer is provided on a conductive substrate.