JPS62118365A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain images of excellent quality without forming moire in any formed image substantially by setting the resolution of an optical system for image exposure substantially lower than the separation period of a specific color by a color separating function part. CONSTITUTION:When fine blue points A and A' on an original 51 are image- formed on the color separating function part of an image carrier (photosensitive body), e.g. a color separation filter 3, the distribution of the quantity of light on the color separation filter 3 is as shown by a curve S if the resolution of the optical system is high. When, however, the blue points A and A' on the original are image-formed on a green filter G or red filter R, no electrostatic latent image is formed. When the blue points A and A' on the original are image-formed on blue filters B and B', an electrostatic latent image is formed. When the resolution of the optical system 31 is lower than the period of a specific color filter, the distribution of the quantity of light on the color separation filter 3 is as shown by a curve S' and the electrostatic latent image is formed separately on the parts of the filters B and B' which color filter the maximal value of the curve is on. Further, more is never formed.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an image forming apparatus, and more particularly to a multicolor image forming apparatus that forms a multicolor image using electrophotography.

Conventionally, many methods and devices used therefor have been proposed for obtaining multicolor images using electrophotography.
In general, it can be broadly classified as follows. One method is to repeat the latent image formation and development with color toner based on the number of separated colors using a photoconductor, to overlap the colors on the photoconductor, or to transfer the colors to a transfer material each time 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, the first method described above has a major drawback in that it takes time to record an image, and it is extremely difficult to speed up the process, since it is necessary to repeat the process of forming and developing a plurality of latent images. The second method described above is advantageous in terms of high speed since it uses multiple photoreceptors in parallel, but it also requires multiple photoreceptors, an optical system, a developing means, etc. However, they are large in size, expensive, and impractical.

Additionally, both of the above methods have a major drawback in that they cannot be repeated multiple times.

In order to fundamentally solve these problems, it would be possible to record a multicolor image on an academic photoreceptor with a single image exposure, but a method that can effectively implement this method has not yet been developed. The reality is that there is not. Particularly, no consideration has been given to the developing conditions for developing with toner of each color, and as a result, it is impossible to avoid disturbances in toner images, decreases in image density, etc.

C. Process leading to the invention In order to fundamentally solve these problems, the present inventors first developed a device that can form a multicolor image by performing a single image exposure on a photoreceptor. invented.

The device includes a photoconductor having a conductive member, a photoconductive layer, and a layer containing a plurality of different types of filters, or a photoconductive layer consisting of a plurality of parts having mutually different spectral sensitivity distributions, and a photoconductive layer on the photoconductive layer. A multicolor image is formed as follows using a photoreceptor having an insulating layer provided thereon. That is, an image is formed by the interface charge density between the insulating layer and the photoconductive layer by applying imagewise exposure to the surface of the photoreceptor at the same time that the surface of the photoreceptor is charged, and by uniformly exposing the image forming surface to specific light, the photoreceptor A potential pattern is formed on the filter portion, and the potential pattern is developed by a developing device containing toner of a specific color to form a monochrome toner image. After potential smoothing, uniform exposure is performed using light that passes through a filter section different from the previous one, and development is performed using a developing device that stores toner of a different color than the previous one. A colored toner image is formed. Thereafter, potential smoothing, uniform exposure, and development are repeated as many times as necessary. As a result, toners of different colors adhere to each filter portion of the photoreceptor, forming a multicolor image (see Japanese Patent Application Nos. 59-83096 and 59-201085). According to this multicolor image forming apparatus, only one image exposure is required, so there is no risk of color shift occurring.

As a result of repeated studies, the inventor of the present invention has found that the above-mentioned multicolor image forming apparatus has solved the problems of the conventional apparatus described above, but the following problems still remain. There was found.

At the current state of the art, the filters (color separation filters) and the portions of the photoconductive layer with different spectral sensitivity distributions, that is, the color separation functional parts, have a separation period of 50 to 500 times.
The limit is μm. On the other hand, in order to sufficiently form a potential pattern corresponding to the color separation function section of each color, the size thereof needs to be a certain degree. Furthermore, since the toner used for development has a particle size of 1 to 20 μm, toner image formation usually requires that each color separation functional portion has a size of 10 μm or more and a period of I μm or more. Also, considering the resolution of the naked eye, to prevent image roughness,
It is desirable that the above-mentioned period is 500 μm or less, preferably 300 μm or less.

By the way, the period of the color separation function is the same as the original image (original).
If the period of the predetermined color portion is approximately the same as that of the predetermined color portion, moiré will occur in the electrostatic latent image formed.

In this case, moiré naturally occurs in the developed visible image.

Moiré is likely to occur when a document is printed (in printing, images are formed by minute halftone dots with a certain period) or has periodic patterns, but if the periodicity between the document and the color separation function is If the difference is sufficient, moiré will not occur.

In printing, there are many patterns that have a periodicity of 50 to 200 lines/inch and a similar periodicity. Its period is 10
It is 0 to 500 μm. Therefore, it often happens that the period of the color separation function section and the period of the document are almost the same, and in this case, moiré occurs.

When an image of an original is made up of very small color dots, a latent image may or may not be formed depending on which color separation feature of the photoreceptor this color dot is projected onto. If a latent image is not formed, this can also be considered a type of moiré.

If a copy is to be made from a copy as an original, the image of the original has the same period as the period of the color separation function section, so moiré will definitely occur.

The present inventor has the above-mentioned Japanese Patent Application No. 59-83096 and
As a result of repeated research to solve the problems still remaining in the multicolor image forming apparatus according to No. 201085, the present invention has been completed.

It is an object of the present invention to provide an image forming apparatus that retains the advantages of a color image forming apparatus and does not cause moiré on any original.

E1 Structure of the Invention The present invention relates to an image carrier having a color separation function section and an image forming apparatus substantially lower than the color separation period.

6 Effects of the invention The operation (principle) of the present invention will be explained below.

The photoreceptor (image carrier) used in the present invention is a photoreceptor in which insulating layers containing a large number of desired filters are superimposed, or a photoconductive layer consisting of a plurality of parts with different spectral sensitivity distributions on a conductive member, for example. This is a photoreceptor, etc., in which an insulating layer is superimposed on the photoconductive layer.

As shown in FIG. 1, there is a slight blue-black A on the original 51.

When A' is imaged by the optical system 31 onto the color separation function section of the image carrier (photoreceptor), for example, the color separation filter 3,
When the resolution of the optical system 31 is high, the color separation filter 3
The light amount distribution above is shown by a curve S. In the figure,
B and B' are blue filters in the color separation filter, G is also a green filter, and R is also a red filter.

If the blue and black A and A' of the original are imaged on the green filter G or the red filter R, no electrostatic latent image will be formed at all. As shown in FIG. 1, when the blue-black ASA' of the original is imaged onto the blue filters B and B', an electrostatic latent image is formed.

If the resolution of the optical system 31 is lower than the period of the specific color filter, the light amount distribution on the color separation filter 3 will be as shown by the curve S' in the figure, and no matter which color filter the maximum value is on, , filter B.

An electrostatic latent image is formed in portion B'. Furthermore, no moiré occurs.

That is, as shown in the plan view in FIG.
If a point in the document of the same color as the filter is imaged at the center of the filter section in the smallest period of
If the resolution of the optical system is adjusted so that the image is formed across two filter sections of that color, moiré will not occur.

However, it goes without saying that forming the above-mentioned image over too many specific color filter sections is undesirable because it causes a decrease in resolution.

In FIG. 1, the image of the curve S' is not substantially resolved. Considering a spectrum having a maximum value intermediate between curves S and S', the predetermined value is substantially lower than that of curve S.

The resolution of an optical system can be expressed by a response function (MTF), similar to photographic film.

When we measure the light intensity distribution of the image formed on the image carrier using a black and white test chart in which many lines are arranged in parallel so that the intervals (periods) gradually increase, we obtain a curve as shown in Figure 3. is obtained. This curve is obtained by exposing photographic paper wrapped around an image carrier, developing it, and scanning and measuring the resulting image with a microdensitometer. The amplitude a of the curve is
It decreases as the period (spatial frequency) of the lines on the test chart increases.

The ratio MTF between the ratio of the amplitude a to the average light amount S and the ratio of the bright/dark amplitude a of the test chart obtained in the same manner to the average light ib is expressed by the following equation.

(a/b) Curve 1 in Figure 4 of the test chart indicates the boundary between whether or not moiré will substantially occur based on the relationship between the period (spatial frequency) of the color separation function section of a specific color and the MTF of the optical system. It shows. The curve: is a locus of points where the spatial frequency of the color separation function unit of a specific color is equal to the resolution of the optical system.

The curve: is MT at a representative value of 300 μm of the smallest period 21 of the color separation function section of the friend specific color shown in Fig. 2.
Fo, passes through point 5. The upper right side of curve 1 is an area where moire occurs, and the lower left side of curve 1 is an area where moire does not substantially occur.

On the other hand, if the MTF of the optical system is made too low, the region where this does not occur is the region on the upper right side of the curve 1i.

In addition, the lower limit of the spatial frequency above which the above-mentioned problem does not occur is two proverbs: curve 101, spatial frequency 2'/m
, passes through the point with MTF 0.5.

For the above reasons, moiré does not substantially occur,
The area where a high-quality image can be obtained is the area surrounded by the curve I, :i in FIG. 4 and the line 111 perpendicular to the horizontal axis on the spatial frequency 2 graph.

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, green, and blue filters that transmit only red light, green light, and blue light, respectively, are used as color separation filters (filters that pass only light in a specific wavelength range) in the insulating layer. Although only the photoreceptor used for full color reproduction will be described, the color of the color separation filter and the color of the toner combined therewith are not limited to the above.

The process of forming a multicolor image using the above 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 a three-color separation filter R, G.
, B is an insulating layer containing 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. 5 [1], 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, the photoconductive layer 2 and the insulating layer A negative charge is induced at the interface.

Next, as shown in FIG. 5 [2], 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 color image is exposed, for example, a red image is exposed Lm. give.

The red light passes through the red filter section R of the insulating layer 3, and in order to make the photoconductive layer 2 below it conductive, the red light passes through the red filter section R of the insulating layer 3, and in this filter section, the positive charges on the insulating layer 3 are erased and the photoconductive layer 2 is absorbed. Also erases the charge of In contrast, the green 3G and blue filter sections 3B do not transmit red light, so some positive charges on the insulating layer and negative charges on the photoconductive layer 2 remain as they are.

The above corresponds to the first latent image formation, but at this stage,
Not only the R portion of the red filter where the charge has been erased, but also the portions 3G and 3B where the charge remains have the same potential on the surface of the insulating layer, and therefore do not function as an electrostatic image. Figure 5 [2]
In this example, the potential after charging is approximately zero, but it may be charged to a negative value.

Next, as shown in FIG. 5 [3], for example, the light source 6B and the blue filter F provide fLfc backcolor light.

When the entire surface is exposed to light, the photoconductive layer 2 below the filter 8 that transmits blue light becomes conductive, and the photoconductive layer 2 in that part becomes conductive.
A part of the negative charge of the filter B and the charge of the conductive substrate 1 are neutralized, and a potential pattern is generated only on the surface of the filter B. G does not transmit blue light, and no change occurs in the ordinary parts. Then, when the charge image on the filter B section is developed with a developer containing negatively charged yellow toner TY, the toner adheres only to the insulating layer B section which has a potential, and development is performed (Fig. 5 [4]).
]).

Next, in order to eliminate the potential difference, the charger 15 performs charging as shown in FIG. 5 [5], and then the entire surface is exposed to green light L0 as shown in FIG. 5 [6]. As in the case of full-surface exposure, a latent image is formed in the green filter portion G. If this image is developed with magenta toner TM as shown in FIG. 5 [7], magenta toner TM will adhere only to the filter G portion. Next, as shown in FIG. 5 [8], after being charged again in the same manner, the entire surface is exposed to red light, but no potential pattern is formed on the red filter portion R, and even after development with cyan toner, no cyan pattern is formed. No toner adhesion occurs.

When the thus obtained toner image is transferred onto a transfer material such as copy paper and fixed, a red image due to a mixture of yellow toner and magenta toner is reproduced on the transfer material.

As for other colors, color reproduction is performed by combining the three-color separation method and three primary color toners as shown in the table below.

In this table, ・:) indicates the state of the first stage of electrostatic image formation, ○ indicates the completed electrostatic image, ・ indicates the developed state, and ↓ indicates that the state in the upper column is maintained as it is. show. Blank columns represent areas where no electrostatic image exists.

(Margin below, continued on next page) Although the above explanation is based on an example using an n-type semiconductor layer, it is of course possible to use a p-type (i.e., high hole mobility) optical semiconductor layer such as selenium. In this case, the basic process is the same except that the positive and negative signs of the charges are all reversed.

Incidentally, if charge injection is difficult during -order charging, uniform irradiation with light is also used.

As is clear from the above description, according to this embodiment, after charging the multicolor image forming photoreceptor and applying imagewise exposure, the entire surface is exposed to light of the same color as one of the filters of multiple types. The steps of applying and developing are repeated depending on the number of types of filters. That is, a fine color separation filter is placed on the photoreceptor, and after image exposure (step [2] in FIG. 5), entire surface exposure with specific light (steps [3] and [6] in FIG. 5) is applied. , a potential pattern is formed for each color portion of the color separation filter and developed using toner of the corresponding color (steps [4] and [7] in FIG. 5), and this process is repeated to obtain a multicolor image. Therefore, if this process is used, a plurality of color separation filters are arranged in a combination of fine stripes or mosaics on a photosensitive layer that is sensitive to the entire visible light range, and then a good and bad light source is used. Image exposure is applied to the entire surface to form a primary latent image in the photosensitive layer below each filter according to the resolved image density, and then the photoreceptor is exposed to a specific light (in this example, the same color as the filter). By exposing the entire surface to light, a second latent image is formed only on the filter of the color, and a potential pattern corresponding to the light intensity of the first latent image forming process is formed. 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 transmitted through the filter, and the same operation is repeated for each resolution to form a multicolor image on the photoreceptor. An image can be formed and a multicolor image can be recorded on the transfer material at once by one transfer.

FIG. 6 is a schematic diagram of an image forming section of a color copying machine suitable for carrying out the above process of this embodiment.

In the figure, reference numeral 41 denotes a photosensitive drum made of a photosensitive member having the configuration shown in FIG. 5, which rotates in the direction of arrow a during a copying operation.

While rotating the photosensitive drum 41, the light source 4A is activated as necessary.
The entire surface of the document is charged with light while being irradiated with light, and the document is exposed to light while being subjected to alternating current or corona discharge of the opposite sign to the electrode 4 from the next electrode 5 having an exposure slit. The next latent image forming step is completed. In this exposure, light from the light source rung 31a is irradiated onto the original 51 placed on the original table 49 and in close contact with the original table 49 by the original valve 50, and the reflected light from the original 51 is reflected onto the mirror 31.
b, an image is formed on the photosensitive drum 41 from the back surface of the electrode 5 via the lens system 31C and the mirror 31d. Light source lamp 3
1a, S-sea 31b, 31d, and lens system 31C constitute an optical system 31.

The document table 49 is configured to move in the direction of the arrow at a predetermined speed, and the optical system 31 is configured to scan and illuminate the document 51. Subsequently, the entire surface of the developing sleeve 7 of the developing device 17Y loaded with yellow toner is exposed to blue light obtained by the combination of the light source 6b and the blue light filter F1.
Developed with Y. Subsequently, after recharging with the charger 15, the light source 5G is turned on.

The entire surface is exposed to green light from the green light source filter FG, and the developing sleeve 7 of the developing device 17M loaded with magenta toner
After development with M, recharging with the charger 16, full exposure with red light from the light source 6FL and red light source filter F1, and development with the developing sleeve 7C of the developing device 17C loaded with cyan toner, the multicolor image is deposited on the photoreceptor drum. An image is formed.

The obtained multicolor toner image is transferred by a transfer electrode 9 onto copy paper 8 that is supplied by a paper feeding means (not shown). However, 21 is a pre-transfer charging electrode, and 22 is a pre-transfer exposure lamp. The copy paper 8 carrying the transferred multicolor toner image is separated from the photoreceptor drum 41 by the separation electrode 10 and fixed by the fixing device 13 to become a completed multicolor copy and discharged outside the machine. . On the other hand, the photoreceptor drum 41 that has completed the transfer is discharged by a discharge electrode 11 while being irradiated with discharge light as necessary, and the toner remaining on the surface is removed by a cleaning device 12 equipped with a cleaning blade, and is used again.

As the developing device used in the present invention, a developing device having a structure shown in FIG. 7 is preferably used.

This developing device 1T includes each developing device 17Y shown in FIG.
17M and 17C, the sleeve 7 and/or the magnetic roll 43 rotates to convey the developer on the circumferential surface of the sleeve 420 in the direction of arrow B. We supply EK. The developer is a one-component magnetic developer, and contains 70 wt% of thermoplastic resin.
, pigment (carbon black) 10wt%, magnetic material 20w
t%, a charge control agent is cross-milled to have an average particle size of 15 μm, and a fluidizing agent such as silica is added thereto.

The amount of band'FL is controlled by a charge control agent. 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 is conveyed in the direction of arrow B. The thickness of the developer layer is regulated by a spike control blade 40 made of a magnetic material during transportation.

A stirring screw 42 is provided in the developer reservoir 47 to sufficiently stir the developer reservoir, and when the toner in the developer reservoir 47 is consumed, the toner supply roller 39 rotates. , toner hopper 38
Toner T is replenished from.

A DC power supply 45 is provided between the sleeve 7 and the photoreceptor drum 41 to apply a developing bias, and the developer is vibrated in the development area E so that the developer is sufficiently applied to the photoreceptor drum 41. AC power supply 4 so that it is supplied to
6 is provided in series with the DC power supply 45. RE is a protection resistance.

In the above image forming process, the developer used may be either a so-called one-component developer using non-magnetic toner or magnetic toner, or a so-called two-component developer using a mixture of toner and a magnetic carrier such as iron powder. I can do it. For development, a method of direct rubbing with a magnetic brush may be used, but especially after the second development, in order to avoid damage to the formed toner image, the developer layer on the development sleeve should be It is essential to use a non-contact development method that does not rub the surface of the photoreceptor. This non-contact method uses a one-component or two-component developer containing non-magnetic toner or magnetic toner that can be freely selected for coloring, creates an alternating electric field in the developing area, and uses an electrostatic image support (photoreceptor) to Development is performed without rubbing the layers.

With repeated development using an alternating electric field as described above, it is possible to repeat development several times on a photoreceptor on which a toner image has already been formed, but if appropriate development conditions are not set, problems may occur during subsequent development. , the toner image formed on the photoconductor in the previous stage may be disturbed, or the toner already adhered to the photoconductor may return to the developing sleeve, which is a developer conveying body, and this may cause a developer of a different color from the developer in the previous stage. If it invades the downstream developing device that houses the agent and causes color mixing, there will be nine problems. From the above considerations, it is clear that the image forming conditions for recording with a desired density and without image disturbance or color mixture using a -component developer or a two-component developer are as follows: -component developer or two-component developer It has become clear that this phenomenon exists in the process used.

Essentially, this development condition is essentially operating the developer layer on the development sleeve without contacting the photoreceptor. Therefore, K is the gap between the image carrier and the developing sleeve.
The thickness is maintained to be thicker than the thickness of the developer layer on the developing sleeve (provided that there is no potential difference between the two).

More desirable conditions include the step of forming a latent image on the image carrier, and the step of developing the latent image using a -component developer to form a plurality of toner images on the image carrier. In the process, the amplitude of the AC component of the developing bias V, c
(V), when the frequency is f (Hz) and the gap between the image bearing member and the developer transporting member that transports the developer is d (d), 0.2≦V, c / (d−f). ≦1.6 is satisfied.

Friend, in an image forming method comprising a step of forming a latent image on an image bearing member, developing the latent image using a developer comprising a plurality of components, and forming a plurality of toner images on the image bearing member. , in each development step, the alternating current component of the development bias is changed to V
, c(V), the frequency is f(H2), and the gap between the image bearing member and the developer transporting member that transports the developer is d(sm), 0.2≦vAC/(d−f) It is preferable to satisfy ((V, c/d)-15007/7≦1.0.

Mayu, in order to prevent uneven development due to the AC component, use -component developer and set the frequency of the AC component to 200 as in the next case.
Hz or more, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 41, the frequency of the AC component is set to 500 Hz to eliminate the influence of the beat caused by the AC component and the rotation of the magnetic roll. It is more desirable to do the above.

The image forming process according to the present invention is as exemplified above, and subsequent toner images are sequentially developed on the photoreceptor drum 41 at a constant density without destroying the toner image formed on the photoreceptor drum 41. To achieve this, as development is repeated, (1) Use toners with a larger charge amount.

■ Gradually reduce the amplitude of the electric field strength of the AC component of the developing bias.

■ Sequentially increase the frequency of the AC component of the developing bias.

It is more preferable to employ these methods alone or in any combination.

That is, toner particles with a larger amount of charge are more easily affected by the electric field. Therefore, if highly charged toner particles adhere to the photoreceptor drum 41 during initial development, these toner particles may return to the sleeve during subsequent development. Therefore, the above-mentioned point (2) is to prevent the toner particles from returning to the sleeve during the subsequent development by using toner particles with a small amount of charge in the initial development. Method (2) is a method in which the toner particles already attached to the photoreceptor drum 41 are prevented from returning 9 by decreasing the electric field strength sequentially as the development is repeated (that is, as the development progresses to a later stage). Specific methods for reducing the electric field strength include a method in which the voltage of the alternating current component is gradually lowered, and a method in which the gap d between the photoreceptor drum 41 and the sleeve T is made wider as the developing stage progresses. In addition, the above-mentioned method (2) is a method in which the frequency of the alternating current component is gradually increased as development is repeated, thereby preventing the toner particles already attached to the photoreceptor drum 41 from returning. These■■
Although (1) is effective when used alone, it is even more effective when used in combination, for example, by sequentially increasing the toner charge amount and gradually decreasing the alternating current bias as development is repeated. Further, when the above three methods are employed, appropriate image density or color balance can be maintained by adjusting the DC bias respectively.

FIG. 8 schematically shows a cross section of a photoreceptor that can be used in the present invention. A photoconductive layer 2 on a conductive member or substrate 1
A color separation filter such as red (R) is placed on top of the filter.
, green (G), and blue (B) filters are laminated.

The conductive substrate 1 may be made of metals such as aluminum, iron, nickel, copper, or alloys 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 photoconductive material such as sulfur, selenium, amorphous silicon or an alloy containing sulfur, selenium, tellurium, arsenic, antimony, etc., or an oxidation of a metal such as zinc, aluminum, antimony, bismuth, cadmium, molybdenum, etc. Inorganic photoconductive materials such as compounds, iodides, sulfides, and selenides;
vinyl carbazole, anthracene, phthalocyanine,
trinitrofluorenone, polyvinyl carbazole,
Organic photoconductive substances such as polyvinylanthracene and polyvinylpyrene are mixed into insulating binder resins such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, acrylic resin, silicone resin, fluorine resin, and epoxy resin. It can be composed of a dispersed material, a functionally separated photosensitive layer consisting of a charge generation layer and a charge transfer layer, or the like.

The insulating layer 3 is made of a transparent insulating material, such as various polymers,
It can be made of resin or the like, and has a colored portion on its surface or inside that acts as a color separation filter. As shown in FIG. 8(a), the colored portion is formed by attaching an insulating material colored by adding a coloring agent such as a dye having a desired color onto the photoconductive layer 2 in a predetermined pattern by means such as printing. Alternatively, as shown in FIG. 8 (bl), a coloring agent is applied to a predetermined pattern by printing, vapor deposition, or other means on a colorless insulating layer 3a that has been uniformly formed in advance on the photoconductive layer 2. Even if a film-like insulating material on which a colored portion is formed in advance is attached on the photoconductive layer, the results shown in FIG. 8(a),
A photoreceptor having the structure shown in (b) can be constructed. Furthermore,
Further covering the surface of the formed colored part with an insulating material 3b,
It may also be configured as shown in FIGS. 8(C) and 8(d).

Although the shape and arrangement of the plurality of types of fine color separation filters constituted by the colored portions are not particularly limited,
When the photoreceptor has a linear shape as shown in FIG. 9(a), for example, a drum shape, it is possible to use either a structure in which the lines are perpendicular to the direction of rotation or a structure in which the lines are parallel to the direction of rotation.

Alternatively, it is preferable to form a mosaic pattern of μm as shown in FIGS. 9(b) and 9(c). If the filter size is too small, it will be easily affected by adjacent parts of other colors,
Furthermore, if the width of one filter is equal to or smaller than the particle size of the toner particles, it becomes difficult to manufacture the filter. Friend, if the size of the filter becomes too large, the resolution and color mixing properties of the image will decrease, and the image quality will tend to deteriorate. Preferably each filter is 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 layer consisting of the color separation filter can be appropriately arranged so that the photoconductive layer can be exposed to light through the layer.

In addition to the structure shown in FIG. 8, the structure schematically shown in FIG. 10 can be used as the photoreceptor. Components l having the same functions as those in FIG. 8 are designated by the same reference numerals as in FIG. 8.

A photoconductive layer 2 is provided on a conductive member or substrate 1, and this photoconductive layer has a photoconductive portion 2R having a desired spectral sensitivity distribution.
12G, 2B, e.g. red (R), green (q), blue CB)K
It contains a large number of sensitive photoconductive parts. An insulating layer Ivi3b is laminated on this photoconductive layer.

The conductive substrate 1 may be made of metals such as aluminum, iron, nickel, copper, or alloys 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 formed to a thickness of 10 to 100 μm and is made of a photoconductive material such as sulfur, selenium, amorphous silicon, or an alloy containing sulfur, selenium, tellurium, arsenic, antimony, etc.; or zinc, aluminum, antimony, etc. Inorganic photoconductive materials such as metal oxides, iodides, sulfides, and selenides such as bismuth, cadmium, and molybdenum; organic photoconductive materials such as vinyl carbazole, anthracenephthalocyanine, trinitrofluorenone, polyvinyl carbazole, polyvinylanthracene, and polyvinylpyrene. Conductive substances dispersed in insulating binder resins such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, Zericarbonate, acrylic resin, silicone resin, fluororesin, epoxy resin, etc., and charge generation. It can be constructed from a functionally separated laminate, etc., in which functions and movement are handled by separate layers.

The insulating layer 3b is formed to have a thickness of 10 to 100 μm, and can be made of a transparent insulating material, such as various polymers and resins.

The photoconductive layer 2 has colored parts 2R12G and 2B, which are photoconductive parts with different spectral sensitivity distributions. It can be formed by depositing a conductive substance on the conductive layer 1 in a predetermined pattern by means such as printing. Or Figure 10 (b
), a charge generation layer 2b (consisting of portions with different spectral sensitivities) is printed on the charge transport layer 2a or the photosensitive layer 2a, which is uniformly formed in advance on the conductive layer 1. It may also be formed by being deposited in a predetermined pattern by means such as vapor deposition or the like.

The planar arrangement of the photoconductive parts 2R12G and 2B may be the same as that shown in FIG. 9.

Next, a specific example carried out with the configuration described above will be described using the apparatus shown in FIGS. 6 and 7.

A friend using the recording device shown in Figure 6. However, the image carrier 41
On a long wavelength sensitized fcCdS photosensitive layer with a thickness of 40 μm, each filter size 100 μm x Zoo
ttm (A rrrjt= 1.8 x 100
μm) is provided with an insulating layer, and its circumferential speed is 18 μm.
0 Tomo/Europe.

This image carrier 41 was charged with a DC scorotron corona discharger 4 so that the surface potential of the image carrier 41 was +2000 V while uniformly exposing the image carrier 41 with a primary charger 40 and a lamp 4A. Next, the spatial frequency is 5.6 lines/min ＜=
A secondary charger 5 consisting of a scorotron corona discharger having an alternating current component is scanned using an optical system 31 having an MTF of 180 μm with an MTF of 0.4. The image carrier 41 was charged at 71C so that its surface potential was 150 V, and during image exposure, infrared and ultraviolet light was cut off by a filter in advance.

An electrostatic image with a contrast of -50 to 300 volts was then formed by uniform exposure through a blue filter. This potential contrast was 1/3 of that when transparent insulation was used. This electrostatic image was developed using a developing device 17Y as shown in FIG.

In developer 17Y, magnetite is contained in the resin by wt%
Contains dispersed particles, average particle size is (up to) μm, magnetization is 3Q e
A developer consisting of Chiaria with a resistivity of 1014 Ωα or more; and a nonmagnetic toner with an average particle size of 10 μm, which is made by adding 10 parts by weight of a benzidine derivative as a yellow pigment and other charge control agents to a styrene-acrylic resin. The conditions were such that the ratio of toner to carrier was 20 wt. Further, the outer diameter of the developing sleeve 7 is 30. ,,The rotational speed is 900 Gauss, the magnetic flux density of the N and S magnetic poles of the IQOrp''s magnet body 43 is 1000 rpm, the thickness of the developer layer in the developing area is 0.7 m, and the developing sleeve 7 and the image The gap with the carrier 41 is 1.OIm, and the developing sleeve 7 is supplied with a DC voltage of +50 V and a frequency of 2.5 KHz, 2000 m.
AC voltage of V/superimposed voltage of Meiron M7 (the amplitude of the positive wave is %
/T x 2000 V) was applied under non-contact development conditions.

Incidentally, while the electrostatic image was being developed by the developing device 17Y, the other developing devices 11M and 17C, also shown in FIG. 2, were kept in a non-developing state. This can be done by disconnecting the developing sleeve from the power source 45, 46 and leaving it in a floating state, or by grounding it, or by actively applying a DC bias voltage of the same polarity as the electrostatic image (i.e., the opposite polarity to the toner charging) to the developing sleeve. achieved by applying n
Among these, it is preferable to apply a DC bias voltage. Further, the driving of the developing device was stopped during non-developing time.

Since the developing devices 17M and 17C are also designed to perform development under the same non-contact developing conditions as the developing device 17Y, the developer layer on the developing sleeve does not need to be removed. The developing device 17M uses a developer having a different structure, in which the toner in the developing device 17Y is changed to a toner containing polytungstophosphoric acid as a magenta pigment instead of a yellow pigment, and the developing device 17C uses the same developer. The toner was changed to a toner containing a copper phthalocyanine derivative as a cyan pigment, and a developer with an n7'c composition was used.◎Of course, it is also possible to use a color toner containing other pigments or dyes, and it is also possible to use a toner containing a copper phthalocyanine derivative as a cyan pigment. The order can also be determined appropriately so that a clear color image can be obtained. In particular, the order of developing colors may be related to the sharpness of the color image and the potential contrast that can be obtained, and therefore needs to be carefully determined.

After the surface of the image carrier 41 developed by the developer 17Y was re-charged to a surface potential of -eov using a scorotron corona charger, uniform exposure was performed through a green filter. The position of the electrostatic image obtained by this is background part -6
It was +300 V with respect to 0 V. This electrostatic image is transferred to the developing sleeve with a DC component of +50V and an AC component of 2.5V.
Kflz, 2000 V tDl and a pressure of $8 AMI were applied, and development was carried out in the developing device 17M under the same conditions as in the developing device 17Y except for the other side.

Similarly, the surface potential was increased to 70VI using a scorotron charger.
After being recharged, uniform exposure was performed through a red filter. As a result, +250V is applied to the background part -70V.
An electrostatic image of V is formed, and this electrostatic image is transferred to a developing sleeve with a DC component of +20V and an AC component of 2.5Kllz, 200
The film was developed by the developer 17C under the same conditions as in the developer 17Y except that a voltage of 0 V was applied.

When this third development is performed and a three-color image is formed on the image carrier 41, the corona discharger 21 and the pre-transfer lamp 22 are activated, thereby transferring the color image. Copy paper 81C with transfer device 9 to make it easier to read.
The image carrier 41 is transferred, separated by a separator 10, and fixed by a hot roller constant fixer 13. 2/G device 1
The residual toner is removed from the surface by the cleaning blade No. 2, and color image formation is performed.
One cycle of color image recording was completely completed at the ninth point in time after passing through the printing device 12.

An image recorded on the original 51 using a test chart having a large number of parallel lines with a spatial frequency of 1 to 20/n is as follows:
The image was extremely clear, and although there was slight moiré, it did not affect the quality of the image and was of good quality.

For comparison, I changed the resolution of the optical system 31 and performed the same recording with MTF of 0.7 at a spatial frequency of 5.6 lines/H. However, the obtained image had a resolution similar to that of the above example. Although the image was a little better in comparison, there was obvious moiré and the image could not be called a good quality image.

A full-color original was copied in the same manner as in the previous example. As a result, the obtained color image was not only in areas where the color toners were loosely adhered to each other, but also in areas where they were closely adhered to each other, without color mixing, and without any moiré. It was extremely clear.

The present invention can also be applied to image formation in which a lens system moves, such as when enlarging or reducing. In this case, basically, the ratio at which the image exposure light spans the plurality of color separation function units with respect to the period of dots of a predetermined color on the original is the same as described above. In other words, if the magnification is m, the original is converted to image exposure of m times the period, so this corresponds to the case where the original is assumed to be m times thicker and image exposure of the same size is performed. .

Regarding development, the development method is not limited to the above-mentioned development method, but as a modified example of a development method that is performed without sliding contact with the photoreceptor, only the toner is taken out from the composite developer onto a developer transport carrier, and the toner is transferred in an alternating electric field. (Japanese Unexamined Patent Publication No. 59-42565, Japanese Patent Application No. 58-231434)
, a method of developing with a monocomponent developer in an alternating electric field by providing a linear or mesh control electrode (Japanese Patent Laid-Open No. 56-125
No. 753), a method of providing a similar control electrode and performing development with a two-component developer in an alternating electric field (Japanese Patent Application No. 58-979)
73) is also included in the multicolor image forming 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, Japanese Patent Publication No. 46-41679, No. 48-
By using the adhesive transfer described in Japanese Patent No. 22763, etc., transfer can be performed without considering the polarity of the toner. In addition, the layer structure of the photoreceptor can be made transparent by providing a transparent insulating layer, a photoreceptor layer, a conductive layer, and a filter to provide primary and secondary charging from the transparent insulating layer side, image exposure from the filter side, and overall exposure. A configuration may also be adopted in which development is performed from the insulating layer side.

Furthermore, 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 the embodiments of the present invention are not limited to this, and various multi-color images can be recorded. Can be widely used in devices, color photo printers, etc.

It goes without saying that the combination of the color of the separation filter and the color of the toner corresponding thereto can be arbitrarily selected depending on the purpose. For example, a process to obtain a two-color copy can be considered, but in this case, a photoreceptor with green (G) filters scattered is used, and the original is made from two colors, red and black. You can use the one that is. In this case, if you use basically the same process as above (however, the entire surface is exposed with G and R1 or G and B), the copy will contain black toner and red toner for the black part of the original. There is a process in which a nearly black copy area consisting of black toner is obtained, and a red area consisting of red toner is obtained for the red area of the document. Therefore, in this specification, the term "multiple filters" refers to a photoreceptor that has a layer consisting of a single color filter-free area (which may be transparent resin or air, etc.). Since the part without this filter can be regarded as a transparent filter, such cases are also included.

Note that the term "electrification" as used herein includes cases where the surface potential becomes O when "charging" is performed or the surface charge disappears.

In addition, in the above explanation, the spectral characteristics of the specific light for full-surface exposure are those of the same color as the filters of the photoreceptor, green (G), blue (B), and red (EL), but the spectral characteristics is not limited to G, B, and 几. In short, it is sufficient that the spectral characteristics are such that a potential turn is formed only in a specific filter section (not necessarily constant) corresponding to the specific light on the photoreceptor by full-surface exposure to specific light, for example, Approximately 500 n when a potential pattern is formed on the blue filter
There is an example of a device with broad spectral characteristics including wavelengths of 400 m or less and full-surface exposure.
Ru.

As described in detail of the invention, the image forming apparatus according to the present invention has a resolution of the optical system for image exposure that is substantially higher than the separation cycle of a predetermined color by the color separation function section disposed on the image carrier. Since the temperature is kept low, the following unique effects can be achieved. That is, when performing image formation based on an original image having periodicity, even if the period of the original image coincides with the separation period of the predetermined color, a minute point of the original image may be separated into multiple color separations of the predetermined color. The image is formed across the functional part, and as a result, the formed image is substantially free from moiré, and a high-quality image is formed.

[Brief explanation of drawings]

1 to 4 are drawings for explaining the present invention in detail. FIG. 1 is a schematic diagram showing a state in which image exposure light from an original image forms an image on a color separation function section; The figure is a schematic diagram showing the resolution of the optical system for the color separation function. Figure 3 is a graph showing the light intensity distribution of image exposure from the test chart on the image carrier. Figure 4 is the spatial frequency of the color separation function. FIG. 5 to 10 are drawings showing embodiments of the present invention, including a process flow diagram, FIG. 6 a schematic diagram of a multicolor image forming apparatus, FIG. 7 a sectional view of a developing device, and FIG. 8. (a), (b), (C), and (d) are cross-sectional views of each photoreceptor, and Fig. 9 (a), (b), and (C) are plan views showing the arrangement of filters on the surface of the photoreceptor. , FIGS. 10(a) and 10(b) are cross-sectional views of each of the other photoreceptors. In addition, in the reference numerals shown in the drawings, 1... fist, conductive substrate 2... photoconductive layer 3... φ- insulating layer 4 containing a color separation filter... - pass/fail converter 5...・Secondary charger 7.7Y, 7M, 7C...Developing sleeve 8...Copy paper 15.16...0 Recharger 17.17Y, 17M, 17C...Developer 31... -Optical system 41...Fist photosensitive drum (image carrier) 51...Original image (original) R...Red filter in the color separation function section G...Green filter in the φ color separation function section B...Back color filter 2B in the color separation function section...Blue light sensitive photoconductive section 2R in the color separation function section...Red light sensitive photoconductive section 2G in the color separation function section... Green light sensitive photoconductive part Fl in the color separation function section...Blue filter Fo...Green filter Fl...Red filter L,...Red light,...Blue light,...Green light TY ...-Yellow toner TM...Magenta toner D...Developer T@-...Toner.

Claims (1)

[Claims] 1. It has an image carrier equipped with a color separation function section and an optical system that performs image exposure on this image support body, and the resolution of this optical system is substantially higher than the separation period of a predetermined color by the color separation function section. image forming device.