JPH0551914B2 - - Google Patents

Description

[Detailed description of the invention]

B. Field of Industrial Application The present invention relates to an image forming apparatus that forms an image on a photoreceptor, and particularly to an image forming apparatus that forms a multicolor image on a photoreceptor for forming a multicolor image used in electrophotography. It is related to. B. Prior Art Many methods and devices used therefor have been proposed in the past for obtaining multicolor images using electrophotography, but they can generally be classified into the following types. One method is to separate colors using a photoconductor, repeat the formation of latent images and development with color toner depending on the number of times, and overlap the colors on the photoconductor, or transfer the colors to a transfer material each time the development is performed. This method involves layering colors on top. Another method uses a device that has multiple photoreceptors corresponding to the number of separated colors, and simultaneously exposes each photoreceptor with a light image of each color, and the latent image formed on each photoreceptor is colored. It is developed with toner, sequentially transferred onto a transfer material, and the colors are superimposed to obtain a multicolor image. However, in the first method described above, the latent image formation and development process must be repeated multiple times, so it takes time to record the image, and a major drawback is that it is extremely difficult to speed up the process. In addition, the second method described above is advantageous in terms of high speed because it uses multiple photoreceptors in parallel, but it requires multiple photoreceptors, an optical system, a developing means, etc., making the device complicated. , large size, high price, and poor practicality. Furthermore, both of the above methods have the major disadvantage that it is difficult to align the image when image formation and transfer are repeated multiple times, and color shift of the image cannot be completely prevented. In order to fundamentally solve these problems, the present inventor previously proposed a method of recording a multicolor image on a single photoreceptor through one image exposure. This is as described above. In other words, a photosensitive layer that is sensitive to the entire visible light range is combined with a plurality of color separation filters (each filter section substantially transmitting only light in a specific wavelength range) in the form of minute lines or a mosaic. Using a photoreceptor with an insulating layer arranged on it, first image exposure is applied to the entire surface, and charges are distributed in the photoconductive layer below each filter according to the decomposed image density (hereinafter referred to as the primary latent image). By exposing the entire surface to light transmitted through a first color separation filter, an electrostatic image (according to the intensity of the first latent image formation process) is formed only on the photoconductive layer below the filter. This is hereinafter referred to as a secondary latent image), which is developed with a color toner of a color corresponding to the type of filter, preferably a color complementary to the color that passes through the filter, and further uniformly charged. By repeating the same full-surface exposure, development, and recharging operations for each color separation image, a multicolor image is formed on the photoreceptor, and a multicolor image is transferred onto the transfer material at once by one transfer. This is to record. Generally, as the image exposure light, light having spectral characteristics extending over the entire visible range, such as fluorescent lamps or halogen lights, is usually used. When this light source was used, the following problems became clear. Since the light passes through the color separation filter, the light with low spectral transmittance of the color separation filter is wasted, resulting in inefficient image exposure. For this reason, a large amount of energy was required for the image exposure light source. This causes an insufficient amount of light during high-speed printing. When performing color reproduction, the problem arises that the color reproduction is not sufficient because the spectral characteristics of the color separation filter and the spectral characteristics of the toner are not ideal. In particular, there was a tendency for colors to lack vividness. C. Object of the Invention The object of the present invention is to produce a good multicolor image at high speed and in a simple process using a photoreceptor that can quickly and easily record a multicolor image without color shift by one image exposure. An object of the present invention is to provide an image forming apparatus capable of forming images. D. Structure of the Invention That is, the image forming apparatus of the present invention charges a photoreceptor having an insulating layer having a plurality of color separation filters on a photoconductive layer, performs image exposure, then exposes the entire surface to specific light, and performs color development. Provided is an image forming apparatus in which the spectral characteristics of the light in the image exposure have a maximum light energy intensity near the wavelength of the maximum spectral transmittance of each color separation filter. It is something to do. Particularly preferably, in the image forming apparatus, the spectral characteristics of the light source used for the image exposure have a maximum light energy intensity near the wavelength of maximum spectral transmittance of each of the color separation filters. A forming device is provided. E. Examples Hereinafter, examples in which the present invention is applied to a multicolor image forming photoreceptor (hereinafter simply referred to as photoreceptor) and a multicolor image forming process will be described in detail. In the following explanation, red light, green light,
A full-color reproduction photoreceptor using red, green, and blue filters that transmit only blue light will be described, but the color of the separation filter and the color of the toner combined therewith are not limited to the above. FIG. 1 illustrates the shape and arrangement of a filter according to the invention. Here, B, G, R,
indicate blue, green, and red filter sections, respectively. FIG. 1A shows a linear type. For example, if the photoreceptor is drum-shaped, the linear type may be perpendicular to the rotation direction or parallel. FIGS. 1B and 1C are mosaic-like, and each filter portion preferably has a length of 10 to 500 μm, as indicated by l in FIG. If the size of the filter part is too small, it will be easily affected by adjacent parts of other colors, and if the width of one filter part is equal to or smaller than the particle size of the toner particles, it will be difficult to create. Become. Furthermore, if the size of the filter section becomes too large, the resolution and color mixing properties of the image will decrease, resulting in deterioration of the image quality. The shape and arrangement are not limited to those shown in FIG. 1, and may be of any kind. FIG. 2 schematically shows a cross section of a photoreceptor that can be used in the present invention. Conductive member or substrate 1
A photoconductive layer 2 is provided thereon, and an insulating layer 3 including a large number of required color separation filters, such as red (R), green (G), and blue (B) filter portions, is laminated thereon. The conductive substrate 1 is made of aluminum, iron, nickel,
It may be made of a metal such as copper or an alloy thereof, and may have an appropriate shape and structure as necessary, such as a cylindrical shape or an endless belt shape. The photoconductive layer 2 is made of a photoconductor such as sulfur, selenium, amorphous silicon or an alloy containing sulfur, selenium, tellurium, arsenic, antimony, etc., or zinc,
Inorganic photoconductive materials of metal oxides, iodides, sulfides, selenides such as aluminum, antimony, bismuth, cadmium, molybdenum, vinyl carbazole, anthracene phthalocyanine, trinitrofluorenone, polyvinyl carbazole, polyvinylanthracene, polyvinylpyrene , polycyclic quinone dyes and pigments, disazo dyes and pigments, etc. are similarly vapor-deposited or resin-dispersed and then applied. Such binder resins include insulating resins such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, acrylic resin, silicone resin, fluorine resin, and epoxy resin. Furthermore, a functionally separated photoelectric material having a charge generation layer and a charge transfer layer is also used. The insulating layer 3 can be made of a transparent insulating material, such as various polymers, resins, etc., and has a colored portion on its surface or inside that functions as a color separation filter. As shown in FIG. 2A, the colored portion is formed by forming an insulating material 3 colored by adding a coloring agent such as a dye or pigment having a desired color onto the photoconductive layer 2 in a predetermined pattern by printing or other means. Make it adhere. In this case, each color of paint is applied multiple times (for example, twice). Alternatively, as shown in FIG. 2B, a coloring agent is deposited in a predetermined pattern on a colorless insulating layer 3a uniformly formed in advance on the photoconductive layer 2 by means of printing, photoresist, vapor deposition, etc. be able to. Alternatively, a photoreceptor having the structure shown in FIGS. 2A and 2B can be constructed by attaching a film-like insulating material 3 on which a colored portion has been formed in advance on the photoconductive layer. Furthermore, the surface of the formed colored portion may be further covered with an insulating material 3C to form a structure as shown in FIG. 2C or D. In addition, both Fig. 1 A to C and Fig. 2 A to D are
A case is shown in which so-called three-color separation filters of red, green, and blue are provided. Next, the process of forming a multicolor image using the above-mentioned photoreceptor will be explained with reference to FIG. The figure schematically shows the image forming process in a portion of a photoreceptor that uses an n-type (that is, high electron mobility) photosemiconductor such as cadmium sulfide as a photoconductive layer. In addition, cross-sectional hatching of each part is omitted. In the figure, 1 and 2 are a conductive substrate and a photoconductive layer, respectively, and 3 is an insulating layer including three color separation filter parts R, G, and B. Further, the graph at the bottom of each figure shows the potential on the surface of each part of the photoreceptor. First, as shown in FIG. 3, when a positive corona discharge is applied to the entire surface by the charger 4, a positive charge is generated on the surface of the insulating layer 3, and correspondingly, a positive charge is generated on the surface of the insulating layer 3. A negative charge is induced at the interface. Next, as shown in FIG. 3, an alternating current or negative discharge is applied by a charger 5 equipped with an exposure slit, and while erasing the charge on the surface of the insulating layer 3, a colored image is exposed, for example, red image exposure L _R is applied. . The red light passes through the red filter section R of the insulating layer 3 and erases the charge in the photoconductive layer 2 in the same filter section in order to make the photoconductive layer 2 below it conductive. On the other hand, since the green filter section 3G and the blue filter section 3B do not transmit red light, the negative charges on the photoconductive layer 2 remain as they are. Further, due to the action of the charger 5, the charge distribution on the insulating layer 3 changes so that the surface potential of the photoreceptor becomes uniform. The primary latent image is formed in the manner described above. The parts of the document that are illuminated by the green and blue components are also
Similar results are given for each filter section.
The primary latent image is a state in which all color components exist as an image-like charge distribution under each filter section. At this stage, not only the portions on the photoconductive layer 2 where the charges have been erased, but also the portions where the charges remain have the same potential on the surface of the photoreceptor, and therefore do not function as an electrostatic image. Although FIG. 3 and 2 show a case where the potential after charging is approximately zero, it may be charged to a negative level. Next, as shown in FIG.
B and the blue light L _B obtained by the blue filter F _B
When the entire surface is exposed to light, the photoconductive layer 2 below the filter B, which transmits blue light, becomes conductive, and a part of the negative charge of the photoconductive layer 2 and the charge of the conductive substrate 1 in this area is neutralized. Therefore, only the charges on the surface of filter B remain, thereby generating a potential pattern. No change occurs in the G and R portions that do not transmit blue light. This is the second latent image. Then, the charge image on filter B is changed to a negatively charged yellow toner Ty.
When developing with a developer containing , the toner adheres only to the surface of the filter portion B, which has a relatively high potential, and development is performed (FIG. 3, 4). Next, in order to eliminate the generated potential difference, the surface potential is made uniform by the charger 14 as shown in FIG. 3, and then the entire surface is exposed to green light as shown in _FIG . As in the case, the green filter part G
A second latent image is formed in the area. If this is developed with magenta toner Tm as shown in FIG. 3, the magenta toner Tm will adhere only to the portion of the filter G. Subsequently, as shown in FIG. 3, after making the surface potential uniform in the same way, the second latent image appearing on the red filter portion R exposed to red light is developed with cyan toner Tc. In the illustrated example, since there is no charge in the photoconductive layer 2 of the red filter R, no potential difference is generated even when the entire surface is exposed, and no cyan toner is attached even when development is performed with cyan toner. When the toner image thus obtained is transferred onto a transfer material such as copy paper and fixed, a red image is reproduced on the transfer material due to the color mixture of yellow toner Ty and magenta toner Tm. Incidentally, it is desirable that the imagewise exposure be performed with light from which the ultraviolet and infrared regions are cut.
As for other colors, as shown in Table 1 below, color reproduction is performed by combining the three-color separation method and three primary color toners. In this table, the symbol "〓" is the state of the first latent image formation stage, the symbol "〇" is the state of the second latent image formation stage, the symbol "〓" is the state of development, and the symbol "↓" is the state of the upper stage. Indicates that the state of the column is maintained as is. A blank space represents a state in which no charge is present in the photoconductive layer.

【table】

[Table] * Filter on photoconductor ** Indicates the presence of Y: yellow, M: magenta, and C: cyan toners.
Although the above explanation is based on an example using an n-type optical semiconductor layer, it is of course possible to use a p-type (i.e., high hole mobility) optical semiconductor layer such as selenium, and in this case, The basic process is the same, just the signs of the charges are reversed. Note that if it is difficult to inject charge during primary charging, uniform irradiation with light is also used. As is clear from the above description, according to this embodiment, after the multicolor image forming photoreceptor is charged and subjected to imagewise exposure, the entire surface is exposed to light that passes through one of a plurality of types of filters. The steps of applying and developing are repeated depending on the type of filter. That is, a fine color separation filter is placed on the photoreceptor, and after image exposure (step 2 in FIG. 3), the entire surface is exposed to three-color separated light (steps 3 and 6 in FIG. 3), and the color separation filter is A secondary latent image is formed for each color portion, and developed using toner of the corresponding color (steps 4 and 7 in Figure 3).
This process is then repeated to obtain a multicolor image. Therefore, according to this process, a photoconductive layer with a photoconductor that covers the entire visible light range and a plurality of color separation filters arranged in a combination of fine lines or a mosaic pattern are used, and the entire surface of the photoconductor is first By applying latent image light to the photosensitive layer below each filter, a primary latent image corresponding to the decomposition image density is formed on the photosensitive layer, and then the entire surface is exposed to light passing through the first color separation filter. Then, a second latent image corresponding to the first latent image is formed on the filter section. Then, it is developed with a color toner of a color corresponding to the color of the filter, preferably a color complementary to the color that passes through the filter,
By repeating similar operations for each color separated image, a multicolor image is formed on the photoreceptor, and a multicolor image can be recorded on the transfer material at once by one transfer. FIG. 4 is a schematic diagram of an image forming apparatus of a color copying machine suitable for carrying out the above process. In the figure,
Reference numeral 41 denotes a photosensitive drum having the configuration shown in FIG. 1, which rotates in the direction of arrow a during a copying operation. While rotating, the photoreceptor drum 41 is irradiated with light as necessary, and the entire surface is charged with a charging electrode 4, and an alternating current or a corona discharge of the opposite sign to that of the electrode 4 is generated from the next electrode 5 having an exposure slit. Manuscript D while receiving
image exposure L is applied, and the primary latent image forming process is completed. Next, the light source 6B and the blue filter for the light source
The entire surface is exposed to the blue light obtained in combination with F _B to form a second latent image of the yellow component. Next, this is developed by a developing device 17Y loaded with yellow toner. Subsequently, after the surface of the photoreceptor is brought to a uniform potential by the electrode 14, the entire surface is exposed to green light from the light source 6G and the green light source filter _FG , and developed by the developer 17M loaded with magenta toner. Further, the potential of the photoreceptor is made uniform by the electrode 15, and the entire surface is exposed to red light from the light source 6R and the red light source filter F _R , and development is performed by the developer 17C loaded with cyan toner. As a result, a multicolor image is formed on the photoreceptor drum 41.
The obtained multicolor toner image is charged by the pre-transfer charging electrode 9A, and then transferred by the transfer electrode 9B onto the copy paper 8 fed by the paper feeding means. The copy paper carrying the multicolor toner image to be transferred is separated from the photoreceptor drum 41 by the separation electrode 10, fixed by the fixing device 11 to become a completed multicolor copy, and discharged outside the machine. . After the transfer, the photosensitive drum 41 is irradiated with static eliminating light to eliminate static electricity, and the cleaning blade 12 in the cleaning device 13 removes the toner remaining on the surface, and the drum 41 is used again. The development in the present invention is preferably carried out by a magnetic brush method, and the developer may be a so-called one-component developer using non-magnetic toner or magnetic toner, or a so-called two-component developer containing a mixture of toner and a magnetic carrier such as iron powder. Both can be used. For development, a method of direct rubbing with a magnetic brush may be used, but in particular, in order to avoid damage to the formed toner image, except for the second development, the development method must be such that the developer layer does not come into contact with the photoreceptor surface. A developing method in which the gap between the developing sleeve and the photoreceptor is set to be larger than the thickness of the developer layer on the sleeve (provided there is no potential difference between the two), for example, U.S. Pat. Publication number 55-18656, patent application No. 58-57446
No., Publication of Japanese Patent Application No. 58-238295, Japanese Patent Application Publication No. 1983-238295
Particularly preferred is the method described in each specification of No. 238296. In this method, a one-component developer consisting of only non-magnetic toner and a two-component developer containing non-magnetic toner are used, and an alternating electric field is formed in the development area, and the electrostatic image support and the developer are Preferably, the development is carried out without contacting the layers. However, a developer using magnetic toner may be used. The color toner used for development is made using known techniques and consists of known binder resins commonly used in toners, various chromatic colors such as organic and inorganic pigments and dyes, and additives such as various charge control agents. A toner for electrostatic development can be used. The carrier is usually iron powder or ferrite powder used for electrostatic images, and more preferably a high-resistance carrier, such as iron powder or ferrite coated with a resin or a resin with fine magnetic particles dispersed in it. Various known carriers can be used, such as magnetic carriers such as . Also, the patent application filed earlier by the applicant in 1982
The developing methods described in the specifications of No. 249669 and No. 58-240066 may be used. FIG. 5 shows each developing device 17Y, 17 shown in FIG.
This shows the basic structure of M, 17C, and when the sleeve 7 and/or the magnetic roll 43 rotate, the developer De is conveyed on the circumferential surface of the sleeve 7 in the direction of arrow B. It is supplied to the developing area E. As the magnetic roll 43 rotates in the direction of arrow A and the sleeve 7 rotates in the direction of arrow B, the developer De is conveyed in the direction of arrow B. The thickness of the developer De is regulated by a spike regulating blade 40 made of a magnetic material while being transported. A stirring screw 42 is provided in the developer reservoir 47 to sufficiently agitate the developer De, and when the toner in the developer reservoir 47 is consumed, the toner supply roller 39 rotates. , Toner Hopper 3
Toner T is replenished from 8 onwards. A DC power source 45 and an AC power source 46 are provided in series between the sleeve 7 and the photosensitive drum 41 to apply a developing bias. R is a protective resistance. Next, the relationship between the filter provided on the front surface of the photoreceptor shown in FIGS. 1 and 2 and the light source that performs image exposure from the front surface will be explained. As already mentioned, when the light source of the image exposure light has a panchromatic wavelength distribution, each filter has a slight transmittance beyond the specific wavelength range, so the exposure light is transmitted to other filters. A considerable amount of charge is also released, and different color information is accumulated in other filter sections. This means that other color information is included in the potential pattern generated in the specific filter section due to full-surface exposure to the specific light. Therefore, the image forming apparatus according to this method has the problem that sufficient color reproduction cannot be achieved by providing image exposure using a panchromatic light source. The inventor of the present invention has set a condition in which specific color information is stored in a specific filter for image exposure light, while the above-mentioned color information is not stored in other filters. Figure 6 shows red (R), green (G), and blue (B) located on the photoreceptor.
An example showing the transmittance of each filter,
The transmittance for each filter light wavelength is shown.
Furthermore, Fig. 7 shows an example showing the relative output with respect to the light wavelength of a fluorescent lamp for image exposure, in which Fig. 7a is a blue fluorescent lamp, Fig. 7b is a green fluorescent lamp, and Fig. 7c is a red fluorescent lamp. This shows the characteristics of FIG. 8 shows the spectral reflectance characteristics of toner for color copying. As described above, the image exposure light source is designed in consideration of the spectral transmittance distribution of the color separation filter so that the image exposure light is effectively transmitted through each color filter. Furthermore, if a light source with a flat energy distribution in the visible region is combined with a color separation filter as shown in FIG. 6, the utilization efficiency of each filter can be expected to be only about 1/10. On the other hand, if, for example, the maximum wavelength of image exposure is matched to the wavelength with the maximum spectral transmittance of each color separation filter, almost all of that wavelength will be used, and the total utilization efficiency will be 1/3 to 1/5. improve to a certain degree. Therefore, it is preferable to set the difference between the wavelength showing the maximum energy of the image exposure light and the wavelength of the maximum spectral transmittance to be within 50 nm. FIG. 9 is a cross-sectional view of the optical system of a color copying machine that uses three types of fluorescent lamps with different colors in parallel as an exposure lamp for exposing an original image. Further, FIG. 10 is a spectral characteristic diagram of the hot cathode fluorescent lamps of each color mentioned above. A transparent glass document table 21 on which a document D is placed is fixed to the upper part of the color copying machine main body.
Below the document table 21 and inside the copying machine main body,
A movable frame 22 is provided. The frame body 22 is formed with two left and right reflective curved surfaces 23A and 23B whose inner surfaces are curved surfaces having an elliptic curve cross section. Four exposure lamps 24B, 2 are placed on the elliptical reflective curved surfaces 23A, 23B at positions with the highest reflection efficiency.
4G and 24R are provided. In addition, the wall surface 23
C and 23D are formed integrally with the frame 22, and are light shielding surfaces that prevent the reflected light from the reflective curved surfaces 23A and 23B from affecting the first mirror 25, and also serve as reflective surfaces. This is a reflective surface that focuses reflected light onto the slit exposure section on the table 21. Thus, the exposure lamps 24B, 24G, 24R
The illumination light from the reflective surfaces 23A, 23B, 23
C and 23D, a portion of the document table 21 is slit-exposed through the opening of the frame 22. This slit exposure width is generally 20 to 30 mm. Between the wall surfaces 23C and 23D of the frame body 22,
A slit 23E having an opening shape of a predetermined size is open. A first mirror 25 is fixed directly below the slit 23E. The above three types of exposure lamps, namely blue fluorescent lamps 24
B, the light emitted by the green fluorescent lamp 24G, and the red fluorescent lamp 24R exhibit the spectral characteristics shown in FIG. 10, respectively. The spectral characteristics of the fluorescent lamps of each color for image exposure are set so that the maximum relative energy intensity is near the maximum wavelength of the spectral transmittance of each of the color filters _FB , _FG , _FR . That is, the blue fluorescent lamp 24
The wavelength showing the maximum exposure energy of B is 450±40nm.
The wavelength of the green fluorescent lamp 24C is 550±40nm.
In addition, if the wavelength of the red fluorescent lamp 24R is set to 650±40nm and matched to the vicinity of the maximum wavelength of the color separation filters F _B , F _G , F _R , almost all of that wavelength can be used. Efficiency is 1/3 to 1/
Improve to about 5. In addition, when considering color reproduction of a copied image, an exposure light source having a flat energy distribution in the visible region is used as a color separation filter F _B , F _G ,
When used in combination with F _R , faithful color reproduction and sharpness may deteriorate due to deviations from the ideal spectral characteristics of the color separation filters F _B , f _G , F _R , deviations from the ideal spectral characteristics due to color toner, etc. Become. Here, color reproduction and sharpness can be improved by making the image exposure light have the same or narrow distribution as the spectral characteristics of each color separation filter. FIGS. 11 and 12 are diagrams illustrating other embodiments of the present invention. FIG. 11 is a sectional view of the optical system of a color copying machine using a single fluorescent lamp using a three-wavelength type phosphor as an exposure lamp for scanning and exposing an original image. FIG. 12 is a spectral characteristic diagram of the fluorescent lamp. In the figure, the frame 32 has the same shape as that for accommodating a general single-tube exposure lamp. As shown in the spectral characteristic diagram of FIG. 12, the exposure lamp 34 has a blue peak wavelength of 435 nm, a green peak wavelength of 545 nm,
The red peak wavelength is 615 nm. The above 3-tube single color fluorescent lamps 24B, 24G, 24R
Alternatively, the illumination light generated from the single-tube three-wavelength fluorescent lamp 34 is reflected on the document surface, passes through the slit 23E, and enters the first mirror 25 fixed to a part of the frame 22 or 32. reflected. Further, this reflected light passes through the second mirror 26 and the third mirror 27, enters the main lens 28, and is guided to the photosensitive surface via the fourth mirror 29. The image exposure intensity of each wavelength is adjusted according to the transmittance of the filter and the spectral sensitivity of the photoreceptor. Further, in order to adjust the density and color tone, the emission intensity of each light source may be changed independently using a configuration as shown in FIG. Next, a specific example of an experiment actually conducted by the present inventor will be explained based on the above conclusion. That is, when a multicolor image was recorded under the conditions shown in Table 2 below, it was possible to record a good color expression by additive color mixture.

【table】

[Table] Not limited to the image forming apparatus using the developing method described above, as a modification of the developing method performed without rubbing the photoreceptor, only the toner is taken out from the composite developer onto the developer transport carrier. A method of performing one-component development using toner in an alternating electric field (Japanese Patent Application Laid-open No. 59-42565
Japanese Patent Application No. 58-231434), a method in which a linear or mesh control electrode is provided and development is carried out with a monocomponent developer in an alternating electric field (Japanese Patent Application Laid-Open No. 125753/1982), There is also a device that performs development using a two-component developer in an alternating electric field (Japanese Patent Application No. 1983-
97973) is also included in the multicolor image forming apparatus method according to the present invention. In the above embodiments, corona transfer is used as the toner image transfer method, but other methods may also be used. For example, Tokuko Sho 46-41679
By using the adhesive transfer method described in Japanese Patent Application Publication No. 48-22763, etc., transfer can be performed without considering the polarity of the toner. Further, a method of directly fixing the photoreceptor, such as electrofax, can also be adopted. In addition, the layer structure of the photoreceptor is changed to include an insulating layer, a photoconductive layer, a transparent conductive layer, and a filter as described in Japanese Patent Application No. 59-199547, and each charge is applied from the insulating layer side, and image exposure is performed from the filter side on the back side. It is also possible to adopt a configuration in which development is performed from the insulating layer side by applying full-surface exposure. Further, the present invention repeats primary charging, secondary charging with a polarity substantially opposite to the primary charging, recharging for erasing the potential pattern after image exposure, whole surface exposure with specific light, and development with specific color toner. It can be used in image forming methods. In addition, all of the above explanations have been made regarding examples of color copying machines that use so-called three-color separation filters and three primary color toners, but embodiments of the present invention are not limited to this, and various types of multicolor image recording are possible. Can be widely used in devices, color photo printers, etc. It goes without saying that the color of the separation filter and the combination of the corresponding toner color can be arbitrarily selected depending on the purpose. In the above-mentioned multicolor image forming process, each whole surface exposure light does not necessarily have to be B, G, and R light.
That is, in the filter portion of the photoreceptor through which the entire surface of the photoreceptor has already been exposed, the charge on the interface between the insulating layer and the photoconductive layer has already been erased, so even if light is transmitted again, there is little change in the surface potential. Therefore, for example, if the entire surface is exposed to red light, then yellow light, then white light,
Even if development is performed in the order of cyan toner, magenta toner, and yellow toner accordingly, a multicolor image with good color reproduction of the document can be obtained. Of course, the present invention is not limited to this, and the entire surface may be exposed with light having other spectral distributions. As mentioned above, when the entire surface exposure light passes through a part of the filter on the photoreceptor more than once, the light should be removed after development to completely erase the charge on the interface between the insulating layer and the photoconductive layer. It is desirable to irradiate it (Japanese Patent Application No. 198171-1982). Furthermore, the filter structure of the photoreceptor is not limited to that described above, and its pattern, arrangement, etc. can be changed in various ways. F. Effects of the Invention In the present invention, in an image forming apparatus, a photoreceptor having an insulating layer having a plurality of color separation filters on a photoconductive layer is charged, image exposed, and then the entire surface is exposed to specific light and color development is repeated. , the spectral characteristics of the light during image exposure have maximum light energy intensity near the wavelength of the maximum spectral transmittance of each color separation filter, so that potential patterns corresponding to different color information are mixed in the multicolor image forming photoreceptor. Therefore, additive color mixing can be realized using the color-separated potentials, and a multicolor image with good color reproduction can be obtained. Moreover, using this photoreceptor, after forming the first latent image by imagewise exposure, the entire surface exposure and development process using light transmitted through at least one type of color separation filter is repeated, which conventionally required multiple steps. The entire surface can be charged and imaged only once, and there is no need to align various images during transfer, and the device can be made smaller, faster, and more reliable. The resulting recorded matter will also be of high quality with no color shift.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIGS. 1A, B, and C are plan views showing the arrangement of filters on the surface of the photoreceptor, and FIGS. 2A, B, C, and D show the arrangement of the filters on the surface of each photoreceptor. Cross-sectional view. Figure 3 1, 2, 3, 4, 5, 6, 7, 8
is a process flow diagram showing an image forming process. FIG. 4 is a schematic diagram of a color copying machine. FIG. 5 is a sectional view of the developing device. Figure 6 is a graph showing the transmittance of each filter, and Figure 7 is a graph showing the wavelength characteristics of fluorescent lamps.
(a) blue, (b) green, and (c) red fluorescent lights. FIG. 8 shows the spectral reflectance characteristics of toner for color copying. 9 and 11 are cross-sectional views of the optical system of a color copying machine, and FIGS. 10 and 12 are spectral characteristic diagrams of fluorescent lamps applied to the present invention. In addition, in the symbols shown in the drawings, 1... conductive substrate, 2... photoconductive layer, 3... insulating layer including a color separation filter, 4, 14, 15... charger, 5... charger equipped with an exposure slit, 8... Copy paper, 17, 17
Y, 17M, 17C...Developer, 24B...Blue fluorescent lamp, 24G...Green fluorescent lamp, 24R...Red fluorescent lamp,
34... Three wavelength type fluorescent lamp, 41... Photosensitive drum, R... Red filter section, G... Green filter section,
B...Blue filter section, F _B ...Blue filter, F _G ...Green filter, F _R ...Red filter, L _R ...Red image exposure,
L _B …Blue light, L _G …Green light, T _y …Yellow toner, T _n …
magenta toner, _Tc ...cyan toner, _De ...developer, T...toner.

Claims (1)

[Claims] 1. After charging and imagewise exposure of a photoreceptor having an insulating layer having a plurality of color separation filters on a photoconductive layer,
In an image forming apparatus that repeats full exposure with specific light and color development, the spectral characteristics of the light in the image exposure have a maximum light energy intensity near the wavelength of the maximum spectral transmittance of each color separation filter. Features of the image forming device. 2. The image according to claim 1, wherein the spectral characteristics of the light source used for image exposure have a maximum light energy intensity near the wavelength of maximum spectral transmittance of each color separation filter. Forming device.