JPS6355573A - Image forming method and its device - Google Patents

Abstract

PURPOSE:To quickly and easily form a good multicolor image by selectively exposing an image carrier with exposure light wavelengths different from one another correspondingly to color separation function parts to form electrostatic latent images and developing electrostatic latent images without exposing the image carrier thereafter to form an image. CONSTITUTION:When positive corona discharge is applied throughout the image carrier by an electrifier 4, positive electric charge is generated on the surface of an insulating layer 3, and negative electric charge is induced on the boundary surface between a photoconductive layer 2 and the insulating layer 3 in accordance with said positive electric charge. AC or negative discharge is applied by an electrifier 5 to erase the electric charge on the surface of the insulating layer 3, and the image carrier is exposed for images correspondingly to respective filter parts by liquid crystal shutters through which B (blue), G (green), and R (red) light beams pass based on picture data. After the image carrier is electrified by an electrifier 15 so that a generated potential difference is cancelled, the image carrier is exposed to a green light LG obtained by a green light source 6G and a liquid crystal shutter FG to form a latent image in the position corresponding to a green filter part G similarly to exposure to blue light. This image is developed with a magenta toner TM to stick the magenta toner TM to only the part corresponding to the filter G.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an image forming method and an apparatus thereof, and in particular, to forming an image (for example, a multicolor image) using an electrophotographic method using a signal based on image data. The present invention relates to an image forming method and an apparatus thereof.

BACKGROUND OF THE INVENTION In the past, many methods and devices used for obtaining multicolor images using electrophotography from digital signals have been proposed, but they can generally be divided into the following types: can. One method is to repeatedly form a latent image using a photoreceptor and develop it with color toner according to the number of separated colors.
Layering colors on a photoreceptor (JP-A-56-144452, JP-A-60-75850, JP-A-60-76766)
(see Japanese Patent Publication No. 2003-110001), or a method in which the color is transferred to a transfer material each time it is developed, and the colors are overlapped on the transfer material. Another method is to use a device having a plurality of photoconductors corresponding to the number of separated colors, and simultaneously expose each photoconductor with a light image of each color.
The latent image formed on each photoreceptor is developed with color toner,
A multicolor image is obtained by sequentially transferring the images onto a transfer material and overlapping the colors.

However, in the first method described above, when multiple writing systems are used, the size of the device increases and costs increase, and when a single writing system is used, multiple latent image formation and development processes are repeated. Therefore, it takes time to record an image, and it is extremely difficult to speed up the process, which is a major drawback.

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, optical systems, developing means, etc., so it requires multiple devices. , large size, high price, and poor practicality. Furthermore, both of the above methods have the major drawback 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, it is sufficient to record a multicolor image on a single photoreceptor with a single image exposure (Japanese Patent Applications No. 59-83096, No. 59-185440, No. 59-185440, 59
-187044, 60-229524).

By the way, in the method of forming an image based on digital signals, it is possible to obtain an image that is faithful to the original image (original document) through image processing, and also, by storing or transmitting the image information, The image can be recreated at any time or place.

However, the reality is that a method for effectively applying such an image forming method to the color image forming apparatus described above has not yet been developed. In particular, how to write image data,
No consideration has been given to the potential pattern formation method, the filter shape, the spectral characteristics of the writing system and the filter, and the development conditions for developing with each color toner. Therefore,
If image formation based on the digital signals described above is applied to the image forming apparatus described above, it is possible to avoid problems such as color shift of images, disturbance of toner images, decrease in image density, and lack of accuracy between filters and image data writing. do not have.

C0 Purpose of the Invention The present invention has been made in view of the above circumstances, and includes:
It is an object of the present invention to provide an image forming method and an apparatus for forming an excellent multicolor image at high speed and easily.

20 Structure of the Invention The first aspect of the present invention is to provide a static image by selectively exposing an image carrier provided with a color separation function section with different exposure wavelengths corresponding to the color separation function section. The present invention relates to an image forming method comprising a step of forming an electrostatic latent image and a step of developing the electrostatic latent image without subsequent exposure.

A second aspect of the present invention is an exposure means for selectively exposing the image carrier with different exposure wavelengths corresponding to the color separation function parts, and a developing means, facing the image carrier in which the color separation function parts I are disposed. The present invention relates to an image forming apparatus having a control means for controlling an exposure means for performing the selective i-exposure based on image data.

E, Example First, preferred embodiments of the present invention will be explained.

(i) Desirable image carriers (photoreceptors) used in the present invention include, for example, a photoconductive layer disposed on a conductive member;
This is a photoreceptor in which an insulating layer including, for example, a large number of filters of different colors is superimposed on the surface of the photoconductive layer. As a similar modification, Japanese Patent Application No. 59-199547;
-201084 can be used similarly.

(ii) The shape of the filter is striped or mosaic.

In forming a multicolor image by repeating the potential pattern formation by the imagewise exposure and the development in accordance with the type of the filter, the development in at least the second and subsequent steps of the repeating process is performed on the image carrier. This is carried out under conditions such that the developer layer on the developing device side does not substantially come into contact with the body.

Further, when implementing the method of the present invention, the following preferred embodiments are (1), (2), or (3).

+1) In the developing step, the gap between the image carrier and the developer transporting member is maintained larger than the thickness of the developer layer formed on the developer transporting member.

(2) A developing process is adopted in which the latent image is developed using a -component developer, and in this developing process, the amplitude of the AC component of the developing bias is set to ■Ac (■), the frequency is set to +(Hz), and the above-mentioned The gap between the image bearing member and the developer transporting member that transports the developer is d(
m), satisfy 0.2≦■Ac/(d・10)≦1.6.

(3) adopting a developing step of developing the latent image using a developer made of a plurality of components including toner and carrier;
In this developing process, the following must be met.

(iii) When repeating the above steps, after each potential pattern formation and development, the potential is flattened by recharging to erase the potential pattern that was formed before the next potential pattern is formed.

(iv) Light used for image exposure is one that passes through a specific filter.

(v) Optical scanning exposure means include laser, LISA, liquid crystal shutter (LC3), light emitting diode (LED), C
RT, optical fiber tubes (OFT) are preferred.

(vi) In the case of a plurality of image exposure means for performing image exposure, a combination means using a mirror optical system can be used.

(vi) In the case of a plurality of image exposure means that sequentially perform image exposure, image exposure can be performed sequentially by image exposure means arranged in parallel.

(vii) Image exposure is performed by writing image data in synchronization with the filter position on the image carrier.

(ix) Image exposure is performed by writing image data asynchronously to the filter position on the image carrier.

(x) The unit of image expression is performed using a plurality of filters of the same color.

(xi) The scanning of the image reading system and the writing of image data onto the image carrier are synchronized.

(xii) In place of the above-mentioned multiple types of filters,
A photoconductive layer having a color separation function described in No. 9-201085 is used. Even if there is an insulating layer at this time,
It doesn't have to be there.

Hereinafter, embodiments 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. First, in the explanation, we will introduce the color separation filter (a filter that passes only light consisting of an infrared wavelength head and a specific wavelength range, which transmits only red light, green light, and blue light together with infrared light). A photoreceptor consisting of an insulating layer and a photoconductive layer using , green, and blue filters will be described, but as will be described later, the colors of the color separation filters and the colors of the toners combined therewith are not limited to the above. Further, the structure of the photoreceptor is not limited to the above.

The process of forming a multicolor image using the above-mentioned photoreceptor will be explained with reference to FIG. The figure shows a portion of a photoreceptor that uses an n-type (i.e., high electron mobility) photosemiconductor such as cadmium sulfide that has been sensitized to long wavelengths as a photoconductive layer.
This is a schematic representation of the image forming process therein, and cross-sectional hatching of each part is omitted. In the figure, 1
．． 2 is a conductive substrate and a photoconductive layer, respectively, and 3 is an insulating layer containing three color separation filters 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. 1 [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. 1 [2], alternating current or negative discharge is applied by the charger 5 to eliminate the charge on the surface of the insulating N3.
Image exposure is performed by a liquid crystal shutter (LC3) through B, G, and R light sources having a center wavelength of 650 nm, corresponding to each filter section. Here, for example, in the case of a red image, a case will be described in which exposure is applied to attach yellow toner and magenta toner. The creation of image data will be detailed later, but yellow image data is sent to the blue (E3) filter section, magenta image data is sent to the green (CG) filter section,
It is assumed that cyan image data is written in correspondence with each red (R) filter section.

Next, as shown in FIG. 1 [3], when exposure is given to light of the same color as the one color in the filter contained in the insulating layer 3, for example, blue light obtained by the blue light source 6B and the liquid crystal shutter F, The photoconductive layer 2 below the filter 8 that transmits blue light becomes conductive, and part of the negative charge of the photoconductive layer 2 in this area and the charge of the conductive substrate 1 are neutralized, and the surface of the filter is neutralized. A potential pattern is generated only when G that does not transmit blue light
, R portions are not changed. Then, when the charge image on filter B is developed with a developer containing negatively charged yellow toner TY, the toner adheres only to the 8 parts of the insulating layer that have a potential, and development is performed (Fig. 1 [4]). .

Next, after charging is performed by the charger 15 as shown in FIG. 1 [5] in order to eliminate the generated potential difference, a green color obtained by the green light source 6G and the liquid crystal shutter F is generated as shown in FIG. 1 [6]. When exposure is applied with the light L6, a latent image is formed in the green filter portion G, as in the case of the exposure with the blue light. If this is developed with magenta toner TM as shown in Fig. 1 [7], magenta toner T will be applied only to the filter G area.
M is attached. If charging is not carried out by the charger 15, a potential pattern remains and the magenta toner TM adheres, causing color mixing, which is not preferable. Subsequently, as shown in FIG. 1 [8], after being charged again in the same way, the red light exposure obtained by the red light source 6R and the liquid crystal shutter F is not given.
No potential pattern is formed on the red filter portion R, and no cyan toner adheres even if 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 due to a color mixture of yellow toner and magenta toner is reproduced on the transfer material.

As for other colors, as shown in the table below, image data is basically separated into three colors: yellow, magenta, and cyan.
Color reproduction is performed by combining the three primary color toners of yellow, magenta, and cyan. It goes without saying that exposure and color toner do not necessarily have a complementary color relationship.
In order to perform faithful color reproduction, it is sufficient that the image data and color toner correspond to each other.

The toner that adheres mainly adheres to a specific filter, and may spread to some other filters as well. For this reason, it is stable for image formation to set the image exposure amount for the second and subsequent times to be 2 to 10 times the half-decrease exposure amount so that the previous toner image is sufficiently transmitted.

Further, the adhered toner spreads during the transfer and fixing steps, and subtractive color mixing is achieved to some extent, so that high image density can be obtained. .

In this table, O indicates an electrostatic image, and . indicates a developed state. Blank columns represent areas where no electrostatic image exists.

(Left below) Color conversion can be performed by changing the combination of image data and color toner. For this purpose, color conversion can be performed by changing the combination of exposure and color toner, or by changing the combination of image data and an exposure system for writing the image data.

In addition, in the above explanation, the spectral characteristics of specific light for exposure are green (G) and blue (B), which are the filters of the photoreceptor.
), the same color as red (R) was used, but the spectral characteristics are not limited to G and BSR.

In short, any spectral characteristic is sufficient as long as it forms a potential pattern only on a specific filter section (not necessarily constant) that corresponds to a specific light on the photoconductor by exposure to a specific light, for example, a potential pattern on a blue filter. Approximately 500 if formed
For example, exposure is performed using a material having broad spectral characteristics including wavelengths of ns+ or less and 40 On+++ or less.

Note that the above explanation is based on an example using an n-type semiconductor layer, but a p-type semiconductor layer such as selenium (i.e., high hole mobility)
Of course, it is also possible to use a photo-semiconductor layer; in this case, the basic processes are all the same except that the positive and negative signs of the charges are all reversed. If it is difficult to inject charges into the photosensitive layer during negative charging, uniform irradiation with light is also used.

As is clear from the above description, according to this embodiment, a multicolor image forming photoreceptor is charged, and then image exposure is applied using each image data in accordance with each filter section, and a plurality of types of filters are used. The process of generating a potential pattern only for one type of filter and the process of performing development are repeated depending on the number of types of filters. That is, a fine color separation filter is placed on the photoreceptor and charged (
After the steps in Figure 1 [1] and [2]), exposure to specific light (
Steps [3] and [6] in Fig. 1) are applied, a potential pattern is formed for each color portion of the color separation filter, and development is performed using toner of a color corresponding to the image data (steps (4) and [6] in Fig. 1). [7]
step) and repeat this to obtain a multicolor image. Therefore, according to this process, a photoreceptor is used in which a plurality of color separation filters are arranged in a combination of fine lines or mosaics on a photosensitive layer with photosensitive properties, and the filters are applied to the lines or mosaic. By forming a charge on the lower photosensitive layer and then exposing the photoreceptor to light of a specific color (in this example, the same color as the filter), a potential pattern corresponding to the light intensity is formed only on the filter of that color. do. Then, it is developed with color toner corresponding to the color of the image data, and a multicolor image is formed on the photoreceptor by repeating the same operation for each separated image, and then a multicolor image is transferred onto the transfer material at once by - times of transfer. Capable of recording color images.

In addition to the image forming method described above, it is possible to use a process in which secondary charging is omitted and image exposure is performed after secondary charging. This process uses a photoreceptor in which no charge is injected due to primary charging, and performs imagewise exposure to a specific light to form charges at the interface between the insulating layer and the photoconductive layer, thereby eliminating areas where the potential has decreased due to exposure. It is to be developed.

That is, after the -order charging, the processes of image exposure to specific light, development, and recharging are repeated in the same manner as shown in FIG. 1 (3) and thereafter to form a multicolor image.

In addition, in the photoreceptor in Special Training No. 59-201085, a similar process is carried out using a photoreceptor consisting only of a photoconductive layer having a color separation function without an insulating layer, that is,
It is also possible to use an image forming method in which the process of imagewise exposure to a specific light and development of a portion where the potential has decreased by an exposed portion is repeated after performing the second electrification.

FIG. 2 is a schematic diagram of an image forming section of a digital color copying machine suitable for carrying out the above process of this embodiment. In FIG. (image carrier), which rotates in the direction of arrow a during a copying operation. While rotating, the photoreceptor drum 41 is irradiated with light from a light source 4A as needed, and the entire surface of the photoreceptor drum 41 is charged by a charging electrode 4, and receives alternating current or corona discharge of the opposite sign from the electrode 4 from the next electrode 5. Next, image exposure of blue light obtained by a combination of the blue light source 6B and, for example, a liquid crystal shutter F is performed, and the image is developed by the developing sleeve 7Y of the developing device 17Y loaded with yellow toner.

Subsequently, after being recharged with the charger 15, it is exposed to green light from the green light source 6G and the liquid crystal shutter F, and developed with the developing sleeve 7M of the developing device 17M loaded with magenta toner.
After recharging with the charger 15, a multicolor image is formed on the photoreceptor drum through exposure with red light from the red light source 6R1 and liquid crystal shutter F, and development with the developing sleeve 7C of the developing device 17C loaded with cyan toner. . 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.
It is ejected outside the aircraft. On the other hand, the toner remaining on the surface of the photoreceptor after the transfer is removed and the photoreceptor is used again.

The filters are not limited to blue, green, and red filters, but should be used in combination depending on the wavelength used for the photoconductive layer and writing system.

In the above example, in the panchromatic photoreceptor, the spectral transmittance of the filter is as shown in FIG.
A writing system used in combination with this is C
RT lasers and LEDs using various exposure wavelengths can be used.

As mentioned above, it is important for each writing to use an exposure system that selectively transmits each filter, and the spectral transmittance of the B, G, and R filters and the wavelength of the exposure light are , is not essential to the invention. That is,
The spectral transmittance distribution of each filter is such that image exposure light selectively passes through each filter depending on the writing system corresponding to the color information used, and a potential pattern can be selectively formed in each filter section. It is necessary.

For example, image exposure of blue light is performed on yellow color information, and development is performed with yellow toner as described above (see Fig. 1).
3] and (4)), the yellow color of the original is reproduced.

If the filter portion to be written by each exposure is a filter having spectral characteristics that transmits only light of a specific wavelength of the exposure light, each exposure dot is made smaller than the size of each unit filter, as shown in FIG. Even if you increase it, it will not be written to other filters. That is, in the example shown in FIG. 5, writing is performed in the B filter area marked with solid hatching for exposure to blue light indicated by a circle, and writing is not performed in the area marked with dashed hatching even if it is exposed. It never happens.

Regarding the relationship between the spectral characteristics of the filter and the image exposure system, it is important to ensure that writing is not substantially performed in areas other than a specific filter section by image exposure.

For example, as shown in FIGS. 6 and 7, the spectral transmittance distributions of the filters shown by solid lines should not overlap with each other, or
Alternatively, it is important that the spectral distributions of the image exposure light indicated by the broken lines do not overlap with each other. Further, the photoreceptor is assumed to have a spectral sensitivity distribution including a spectral transmittance distribution of each filter or image exposure light.

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. Can be done. Direct rubbing with a magnetic brush may be used for development, but especially after the second development, in order to avoid damage to the formed toner image, the developer layer on the development sleeve should not touch the surface of the photoreceptor. It is essential to use a non-contact development method that does not rub the surface. 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 development area, and applies the developer to an electrostatic image carrier (photoreceptor). Development is performed without rubbing the layers. This will be explained in detail below.

In 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, This may disturb the toner image formed on the photoconductor in the previous stage, or the toner already attached to the photoconductor may return to the developing sleeve, which is the developer conveying body, and this may cause a developer of a different color from the developer in the previous stage to be disturb. From the considerations above, a -component developer or a two-component developer is used to create a solution that has the desired density and prevents image distortion. It has become clear that image forming conditions for recording without color mixture exist in processes using both a -component developer and a two-component developer. Essentially, this development condition is essentially operating the developer layer on the development sleeve without contacting the photoreceptor.

To this end, the gap between the image carrier and the developing sleeve is maintained to be larger than the thickness of the developer layer on the developing sleeve (provided there is no potential difference between them).

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 developing process, the amplitude of the AC component of the developing bias is changed to ■.

(V), the frequency is +(Ilz), and when the gap between the image bearing member and the developer transporting member that transports the developer is d (ms), 0.2≦Vac/ (ti-1-)≦1 .6 must be satisfied.

Further, in the image forming method, the step of forming a latent image on an image carrier, and developing the latent image using a developer made of a plurality of components to form a plurality of toner images on the image carrier, In each development process, the amplitude of the AC component of the development bias is
It is preferable to satisfy the following conditions: Ae (■), the frequency + (llz), and the gap between the image carrier and the developer conveying body that conveys the developer d (am).

That is, as a result of research into a method of forming an image by repeating the latent image formation and development, the present inventor found that by selecting development conditions such as AC bias and frequency, it is possible to create a high-quality image without causing image disturbance or color mixing. We have discovered that there are areas where high-quality images can be obtained.

In a method in which toner images are sequentially superimposed on an image carrier (for example, on a photosensitive drum), it is necessary to perform development at an appropriate density without disturbing the toner image previously formed on the image carrier during development. Here, superimposition means that a toner image is formed on the image carrier in advance, and then an electrostatic latent image is formed on the image carrier by recharging and uniform exposure with specific light.
This refers to depositing toner on the electrostatic latent image from one or more developing devices to form a toner image.

As a result of the study, in order to satisfy this condition, the gap d (m) (hereinafter sometimes simply referred to as gap d) between the image carrier and the developer transport body in the development area, the amplitude vAc of the alternating current component of the development bias ( It has become clear that it is difficult to obtain an excellent image even if the values of (2) and frequency 1 (Ilz) are determined independently, and that these parameters are closely related to each other. Therefore, using the color copying machine shown in FIG. 2, an experiment was carried out using -component magnetic toner in the developing device 17 shown in FIG. 3 while changing parameters such as the voltage and frequency of the AC component of the developing bias. As a result, the results shown in FIGS. 8 and 9 were obtained. Note that the photosensitive drum 41
A toner image is previously formed on the surface. This developing device 17
1 corresponds to the developing units 17Y, 17M, and 17C shown in FIG. The developer is conveyed in the B direction and the developer is supplied to the development area E. The developer is a one-component magnetic developer, and is made by kneading and pulverizing 70-1% thermoplastic resin, 10% pigment (carbon black), 20% magnetic material, and charge control agent to give an average particle size of 15 μm. and a fluidizing agent such as silica is used. The amount of charge 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 O moves in the direction of arrow B.
conveyed in the direction.

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 O. When the toner in the developer reservoir 47 is consumed, the toner supply roller 39 rotates. , toner T is replenished from the toner hopper 38.

A DC power supply 45 is provided between the sleeve 7 and the photoreceptor drum 410 to apply a developing bias, and the developer O 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. R is a protective resistance.

In FIG. 8, the gap d between the photosensitive drum 41 and the sleeve 7 is 0.7 mm, the thickness of the developer layer is 0.3 ta, the DC component of the developing bias applied to the sleeve 7 is 50 V, and the AC component of the developing bias is 0.7 mm. When the frequency is set to 1kllz and the maximum potential of the photoreceptor due to uniform exposure after charging is set to 500V,
The relationship between the amplitude of the alternating current component and the image density of a black toner image formed on a non-exposed area (the exposed area potential is OV) on the photoreceptor drum 41 is shown. The amplitude EAC of the AC electric field strength is the value obtained by dividing the amplitude vAc of the AC voltage of the developing bias by the gap d. Curves A, B, and C shown in FIG. 8 indicate that the average charge amount of the magnetic toner is -5 μc/g and −3 μc/g, respectively.
.

This is the result when -2 μc/g was used.

For both of the three curves ASB and C, the image density is high when the amplitude of the alternating current component of the electric field is 200 V/n or more and 1.5 kV/ms or less, and when it is 1.6 kV/m or more, the image density is It was observed that the formed toner image was partially destroyed.

Figure 9 shows the frequency of the AC component of the developing bias at 2.5k.
Hz, and shows changes in image density when alternating current electric field strength, etc. are changed under the same conditions as in the experiment shown in FIG.

According to this experimental example, when the amplitude EAC of the alternating current electric field strength is 500 V/wm or more and 3.8 kV/m- or less, the image density is high, and when it is 3.2 kV/me or more, the image density is A portion of the Toner statue was destroyed.

As can be seen from the results in Figures 8 and 9, the image density changes to saturate or slightly decrease after a certain amplitude, but the value of this amplitude is different from curves A, B, and C. As can be seen, this can be obtained without much dependence on the average charge amount of the toner. The reason may be as follows. That is, in the negative component developer, the amount of charge is expected to be widely distributed across positive and negative directions due to mutual friction between toner particles. Therefore, the average charge amount will be a small value, but
In reality, toner with a large charge amount, for example, a size of 20 μc/g or more, exists at a certain rate, and it is considered that such toner is mainly used for development. Even if the average charge amount is controlled by a charge control agent, the proportion occupied by these toners having a large charge amount does not change significantly, and as a result, it is considered that almost no change in the development characteristics is observed.

Now, when we conducted an experiment similar to that shown in Figures 8 and 9 while changing the conditions, we found that the amplitude EA of the alternating current electric field strength.

We were able to sort out the relationship between frequencies, and obtained the results shown in Figure 10.

In FIG. 10, the areas marked with ■ are areas where uneven development is likely to occur due to the low-frequency development bias, the areas marked with ■ are areas where the effect of the AC component does not appear, and the areas marked with ■ are areas where development has already been formed. Φ■ is a region in which the effect of the alternating current component appears and sufficient development density is obtained, and destruction of the already formed toner image does not occur, and Φ■ is a particularly preferable region.

This result shows that in order to develop the next (later stage) toner image at an appropriate density without destroying the toner image previously formed on the photoreceptor drum 41 (at the previous stage), the amplitude of the alternating current electric field strength must be It is shown that there is an appropriate range for that frequency, and the reason is considered to be due to the reasons described below.

In the region where the image density tends to increase with respect to the AC field strength amplitude EAc, that is, in the density curve A of FIG. 8, in the region where the AC field strength amplitude EAc is 0.2 to l k V / am, The alternating current component of the developing bias serves to make it easier to exceed the darkness value at which the toner flies from the sleeve, and even toner with a small amount of charge is attached to the photoreceptor drum 41 and development is performed. Therefore, the amplitude EA of the AC field strength
As c increases, image density increases.

On the other hand, as the amplitude of the AC electric field increases, the image density becomes saturated or decreases slightly (for example, for the density curve A in Figure 8, the amplitude EAc of the AC electric field strength is 1 kV).
There are several possible reasons for this. As the amplitude EAC of the alternating current electric field strength increases, the toner vibrates more strongly, and the clusters formed by toner aggregation become easier to break. Only toner with a large charge is selectively attached to the photoreceptor drum 41, and small Even if the charged toner adheres to the -transformation photo drum 41, its mirror image force is weak, so it is likely to return to the sleeve 7 due to the alternating current bias. Furthermore, if the amplitude of the electric field strength of the alternating current component is too large, the charge on the surface of the photoreceptor drum 41 leaks, making it difficult to develop the toner. In reality, it is thought that these factors overlap to saturate or lower the image density.

On the other hand, when the amplitude Esc of the alternating current electric field strength is increased, the toner image previously formed on the photoreceptor drum 41 is destroyed, as described above, and the greater the alternating current component, the greater the degree of destruction. The reason for this is thought to be that the AC component exerts a force on the toner adhering to the photoreceptor drum 41 to pull it back toward the sleeve 7. Photosensitive drum 41
When developing toner images by sequentially superimposing them on top of each other, it is a fatal problem that the already formed toner images are destroyed during subsequent development.

Also, as can be seen by comparing the results in Figures 8 and 9, when we experimented by changing the frequency of the AC component, there was a tendency for the image density to decrease as the frequency increased;
This is because the toner particles cannot follow changes in the electric field, so the range in which they vibrate is narrowed, making it difficult for them to be attracted to the photosensitive drum 41.

Based on the above experimental results, the present inventor has determined that in each development step,
When the amplitude of the AC component of the developing bias is vAc (V), the frequency is +()Iz), and the gap between the photosensitive drum 41 and the sleeve 7 is d (ms), 0.2 ≦Vac/ (d l
) It was concluded that if development is performed under conditions satisfying ≦1.6, subsequent development can be performed at an appropriate density without disturbing the toner image already formed on the photoreceptor drum 41. be. In order to obtain sufficient image density and not disturb the toner image formed up to the previous stage, the image density should be 0.4, which is the region in which the image density tends to increase with respect to the alternating current electric field in FIGS. 8 and 9. It is more desirable to satisfy the condition of ≦Vac/ (d l )≦1.2, and furthermore, within this region, there is a region where the electric field is slightly lower than that at which the image density is saturated, 0.6≦VAc/ (d −'f ) It is more desirable to satisfy ≦1.0.

In addition, in order to prevent uneven development due to the AC component, the frequency A of the AC component is set to 20011z or more, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 41, the AC component and the magnetic roll are In order to eliminate the influence of beats caused by the rotation of the AC component, it is more desirable that the frequency of the AC component be 50011z or higher.

Next, an experiment was conducted using a two-component developer using the developing device 17 shown in FIG. 3 in the same manner as described above, and the results shown in FIGS. 11 and 12 were obtained. In addition, developer O
is a two-component developer consisting of a magnetic carrier and a non-magnetic toner, and the carrier has an average particle size of 20 μm and a magnetization of 30 emu.
/ g, a carrier created by dispersing fine iron oxide in a resin so as to exhibit a physical property of resistivity 1014 Ω-cm. After tapping, a load of 1 kg/aa is applied on the packed particles, and a
This value is obtained by reading the current value when applying a voltage that generates an electric field of 000 V/am. The toner is made by adding a small amount of a charge control agent to 90-t% of a thermoplastic resin, 10% of a pigment (carbon blank), and pulverizing the mixture.
The particles with an average particle size of 10 μm were used. The carrier is obtained by kneading, pulverizing, and classifying 30% thermoplastic resin and 70% iron oxide fine powder. The toner was mixed with 80 wt % of the carrier at a ratio of 20 wt % to obtain developer O.

Note that the toner is negatively charged due to friction with the carrier.

FIG. 11 shows the gap d between the photosensitive drum 41 and the sleeve 7.
is l, Qmm, developer layer thickness is 0.7mi+, maximum potential of photoreceptor is 500V, DC component of developing bias is 50V,
The amplitude of the AC component when the frequency of the AC component is set to 1 kHz and the non-exposed area (exposed area potential O) on the photoreceptor drum 41
V) shows the relationship with the image density of the black toner image formed. The amplitude EAC of the AC electric field strength is the value obtained by dividing the amplitude vAc of the AC voltage of the developing bias by the gap d. 1st
Curves A, B, and C shown in Figure 1 each have an average charge amount of -30 μc/g.

These are the results when using those whose charge was controlled to -20 μc/g and -15 μc/g. In the three curves A, B, and C, the effect of the AC component appears when the amplitude of the AC component of the electric field is 200 V/m or more, and when the amplitude is 2500 V/tm or more, the toner image that has been previously formed on the photoreceptor drum is was observed to be partially destroyed.

Figure 12 shows that the frequency of the AC component of the developing bias is 2.5.
The graph shows the change in image density when alternating current electric field strength EAC is changed under the same conditions as in the experiment shown in FIG. 11.

According to this embodiment, when the amplitude EAc of the alternating current electric field strength exceeds 500 V/+n, the image density becomes large, and when it exceeds 4 kV/m (not shown), the toner image previously formed on the photoreceptor drum 41 becomes Some parts were destroyed.

As can be seen from the results in Figures 11 and 12, the image density changes to become saturated or to decrease slightly after reaching a certain amplitude, and the value of this amplitude is determined by curves A, B, and C.
As can be seen, this can be obtained without much dependence on the average charge amount of the toner. The reason may be as follows. In other words, in a two-component developer, the toner is charged due to friction with the carrier and mutual friction between the toners, and the amount of charge on the toner is expected to be distributed over a wide range, although not as much as in the -component developer. It is thought that toner with a large amount of charge is preferentially developed. Even if the average charge amount is controlled using a charge control agent, the proportion of toner with a large charge amount does not change significantly, and as a result, although changes in development characteristics may be observed, they are not considered to be significant. .

Now, when experiments similar to those shown in FIGS. 11 and 12 were conducted while changing the conditions, the relationship between the amplitude EAc of the alternating current electric field strength and the frequency K was sorted out, and the results shown in FIG. 13 were obtained.

In Fig. 13, the area marked ■ is an area where uneven development is likely to occur due to low-frequency development bias, and the area marked ■ is an area where the effect of the AC component does not appear.The area marked ◎ is already formed. Areas where the toner image is likely to be destroyed, ■ and ■ are areas where the effect of the alternating current component appears and sufficient development density is obtained, and where the already formed toner image is not destroyed, and ■ is a particularly preferable area. .

As a result, in order to develop the next (later) toner image at an appropriate density without destroying the toner image formed in the previous stage on the photoreceptor drum 41, it is necessary to , indicating that there is an appropriate range, and the reason for this is the same as in the case of the one-component developer described above.

That is, in a region where the image density tends to increase with respect to the amplitude EAC of the AC electric field strength, for example, for the density curve A in FIG. 11, the amplitude EAc of the AC electric field strength is 0.2 to 1.2 kV.
/ Regarding the area that will become the fin, the alternating current component of the developing bias works to make it easier for the toner to fly from the sleeve to exceed the darkness value, and even a small amount of toner is attached to the photoreceptor drum 4 times and subjected to development. Ru. Therefore, as the amplitude of the AC field strength increases, the image density increases.

On the other hand, in the region where the image density is saturated with respect to the amplitude EAC of the AC electric field strength, the amplitude E of the AC electric field strength is
For regions where AC is 1.2 kV/fin or higher, this phenomenon can be explained as follows. In other words, in this region, the amplitude of the alternating current electric field strength increases (as the amplitude increases, the toner vibrates more strongly, and the clusters formed by toner agglomeration are more likely to break down, and only toner with a large charge is selectively applied to the photoreceptor drum. Toner particles with a small charge attached to the photo drum 41 are difficult to be developed.Furthermore, even if the toner particles with a small charge are attached to the -transformed photo drum 41, the image force is weak, so the toner particles are returned to the sleeve 7 by the alternating current bias. Furthermore, if the amplitude of the electric field strength of the alternating current component is too large, the charge on the surface of the photoreceptor drum 41 leaks, making it difficult to develop the toner.In reality, these factors overlap. It is considered that the image density remains constant despite the increase in the AC component.

Furthermore, if the AC field strength is increased, for example, the amplitude is increased to 2.5 kV/m or more under the conditions where curve A in Fig. 11 is obtained.
As mentioned above, it was found that the toner image previously formed on the photoreceptor drum 41 was destroyed, and the larger the alternating current component, the greater the degree of destruction. The reason for this is thought to be that the AC component exerts a force on the toner adhering to the photoreceptor drum 41 to pull it back toward the sleeve 7 .

When developing toner images by sequentially overlapping them on the photoreceptor drum 41, it is a fatal problem that the already formed toner images are destroyed during the subsequent development.

Also, as can be seen by comparing the results in Figures 11 and 12, when we experimented by changing the frequency of the AC component, the higher the frequency, the lower the image density.This is because the toner particles This is because the vibration range is narrowed because it cannot follow changes in the electric field, making it difficult to adhere to the photoreceptor drum 41.

Based on the above experimental results, the present inventor has determined that in each development step,
The amplitude of the AC component of the developing bias is vAc (V), the frequency is + (Hz), and the gap between the photosensitive drum 41 and the sleeve 7 is d.
(m), 0.2≦Vac/ (cl, +
) If development is performed under conditions satisfying t(VAc/d) -15003d≦1.0, subsequent development can be performed at an appropriate density without disturbing the toner image already formed on the iris of the photosensitive drum 4. The conclusion was that it is possible. In order to obtain sufficient image density and not disturb the toner image formed up to the previous stage, among the above conditions, 0.5≦Vac/ (d −+) i (Vac/d) −1500)/ It is more preferable to satisfy 'r≦1.0. Furthermore, especially when 0.5≦V ac/(d −+ ) is satisfied, a clearer multicolor image with no color turbidity can be obtained, and even if the developing device is operated many times, different color toners will not be mixed into the developing device. It can be prevented.

In addition, in order to prevent uneven development due to the AC component, the frequency of the AC component is set at 200
Hz or more, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 4I, the frequency of the AC component is 500 llz in order to eliminate the influence of the AC component and the beat caused by 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.

■ Gradually increase the frequency of the AC component of the development phase.

It is more preferable to employ these methods individually 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, as described above, by using toner particles with a small amount of charge in the initial development, the toner particles are prevented from returning to the sleeve during the subsequent development. Method (2) is a method in which the toner particles already attached to the photoreceptor drum 41 are prevented from returning by decreasing the electric field strength sequentially as development is repeated (that is, as development progresses to later stages). 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 7 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 it 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 AC 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. 14 schematically shows a cross section of a photoreceptor that can be used in the present invention. A photoconductive layer 2 is provided on a conductive member or substrate 1, and a filter layer 3 containing a large number of required filters, such as red (R), green (G), and blue (B) filters, is provided thereon.
An insulating layer 3 having a thickness of a is laminated.

The conductive substrate 1 may be made of metals such as aluminum, iron, nickel, copper, or alloys thereof, and may have a cylindrical shape, an endless belt, or a suitable shape and structure as required.

Photoconductor N2 is a photoconductor such as sulfur, selenium, amorphous silicon or alloys containing sulfur, selenium, tellurium, arsenic, heptimony, etc.; or oxidation of metals such as zinc, aluminum, antimony, bismuth, cadmium, molybdenum, etc. Inorganic photoconductive substances such as iodides, sulfides, and selenides, and azo, disazo, trisazo, and phthalocyanine dyes and pigments; vinyl carbazole, trinitrofluorenone, oxadiazole, hydrazone compounds, stilhen derivatives, styryl. Charge transport materials such as derivatives such as polyethylene, polyester, polypropylene, polystyrene,
polyvinyl chloride, polyvinyl acetate, polycarbonate,
It can be constructed by dispersing it in an insulating binder resin such as acrylic resin, silicone resin, fluororesin, or epoxy resin, or by having a layered structure of a charge generation layer (CGL) and a charge transfer layer (CTL). Special application 1986-2
No. 45178, No. 60-229524).

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 part (filter layer) 3a on its surface or inside that acts as a filter. As shown in FIG. 14(a), the colored portion is a filter N colored by adding a coloring agent such as a dye having a desired color.
3a onto the photoconductive layer 2 in a predetermined pattern by means such as printing, or a transparent insulating layer 3 with a coloring agent uniformly formed on the photoconductive layer 2 in advance, as shown in Figure 14).
It can be formed by adhering it to a predetermined pattern on the surface of b by means such as printing, vapor deposition, dyeing, electrodeposition, etc. Furthermore, the photoreceptor having the structure of the fourteenth (a) (mountain) can also be constructed by attaching a film-like insulating material on which a colored portion has been formed in advance on the photoconductive layer. Furthermore, the surface of the colored portion thus formed is further covered with a transparent insulating layer 3b, and as shown in FIG. 14(C) and (d).
It may also have a configuration like this.

Note that each filter preferably has high resistance. If the resistance is low, they can be electrically insulated from each other by providing a gap or interposing an insulator.

Additionally, the present applicant had previously proposed a photoreceptor (patent application filed in 1983).
-199547, 59-198166, 59-
For example, as shown in FIG. 15, an insulating layer 3c is provided on one surface of the photoconductive layer 2, and a transparent conductive layer is provided on the other surface. 71101 and color separation filter 3a (the color separation filter may be conductive) are sequentially deposited to form 82 layers. The transparent conductive layer 101 is formed by depositing ITO, for example.

In the photoconductor with this structure, charging is performed from the insulating layer 3c side,
Image exposure is performed from the side 3a consisting of color separation filters.

Further, as shown in FIG. 16, for example, in the case of a drum-shaped photoreceptor, a transparent insulating layer 3b is provided on the photoconductive layer 2, and a minute gap md is provided on the transparent insulating layer 3b so that R, G, and day filters are separated from each other. A layer 103 (similar to the layer 3a) can also be provided coaxially. That is, a cylindrical body 103 made of R, G, and El filters is coaxially fitted onto a drum-shaped photoreceptor having no filter, leaving a minute gap md, and is integrated. With such a structure, any one can be selected and replaced from the filter layers of the structures shown in FIGS. 17(a) to (d) and FIG. 18(1) to (e) (details will be described later). and can be used. However, the gap md should not be too large so that the image of the filter cell is not extremely blurred and projected onto the insulating layer and the photoconductive layer.

Further, the transparent insulation N3b and the filter N103 may not be completely separated from each other, but may be in contact with each other.

The distribution layer 3a of the color separation filter, which is formed by adhesion of colorants, colored resins, etc. on the insulating layer 3, has R, G,
Although the shape and arrangement of the fine filters such as B are not particularly limited, in the case of a linear shape as shown in FIG. It is possible to use both the direction perpendicular to the moving direction shown in (Fig. 17 (al)) and the direction parallel to the movement direction (Fig. 17 (b)). It is preferable to configure the figure 17 (C), +d) as 90
A layer-rotated configuration can also be used. These angles are preferably θ° or rotated by 90 layers, but are not limited thereto.

The combination of the filter color and the corresponding toner color can be arbitrarily selected depending on the purpose.

For example, it is conceivable to obtain a copy made of four color toners including black toner, but for this purpose, one type of filter may be added in addition to the three types of filters described above. For example, it is possible to use a filter in which filters having spectral transmission characteristics only in the infrared region are scattered. In this case, using essentially the same process as described above, a tight image with added black toner is obtained. Therefore, the term "multiple types of filters" in this specification means
It may be a photoreceptor that has a layer consisting of a monochromatic color filter-free area (which may be transparent resin or air, etc.), or it may have two, four, or more types of filters. It encompasses.

FIGS. 18(a) to 18(e) show examples of layers consisting of four types of filters. Similar to the structure in FIG. 17, (al, (b
) shows each filter arranged in a linear pattern, (C), (d)
, (e) are arranged in a mosaic pattern. In the diagram,
For example, it may be something that only transmits infrared light, in short,
The color of the filter is not essential as long as the potential pattern can be selectively formed on each filter portion by exposure. The spectral transmittance distribution of each filter may be as shown in FIG. 19, for example.

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.

Again, in most of the above explanations, green (G), blue (B), and red (R) are used as the spectral characteristics of the specific light for exposure and the spectral characteristics of the photoreceptor filter. , the spectral characteristics are not limited to G, B, and R. In short, the spectral characteristics of the exposure and filter may be such that a potential pattern is formed only in a specific filter portion (not necessarily constant) on the photoconductor corresponding to the specific light by exposure to the specific light. Further, when forming a potential pattern on a specific filter, the next exposure may be performed with a light having broad spectral characteristics including the wavelength of the previous exposure. In this case, as shown in Japanese Patent Application No. 59-198171, it is effective to prevent color mixture by performing the next exposure after completely erasing the charge on the photoconductive layer in the toner-attached area by charging after each development. .

It is also possible to use a photoreceptor in which the photoconductive layer is provided with a color separation function without providing the layer 3a made of a filter as described above. Figures 20 and 21 were previously proposed by the applicant (Japanese Patent Application Nos. 59-201085 and 60-245177).
An example of a photoreceptor is shown. The photoreceptor in FIG. 20 has a conductive substrate 1
a photoconductive part 2R12G having the required spectral sensitivity distribution on the top;
2, a photoconductive layer 102 including a large number of photoconductive parts sensitive to red (R), green (G), and blue (B), for example, is provided, and a transparent insulating layer 3b is provided thereon. . In the photoreceptor shown in FIG. 21, a charge transfer layer 112b is provided on a conductive substrate 1, and a portion 2R1 having a different spectral sensitivity distribution is formed on the charge transfer layer 112b.
It has a structure in which a charge generation layer 112a made of 2G is provided, and a transparent insulating layer 3b is further provided thereon. In the photoreceptor shown in FIG. 21, a photoconductive layer 112 is composed of a charge generation layer 112a and a charge transfer layer 112b. The planar structure of the photoconductive layer 102 in FIG. 20 and the charge generation layer 112a in FIG. (a) - (a)
A planar structure similar to that shown in is sufficient.

Furthermore, the structure shown in FIGS. 20 and 21 without an insulating layer can also be used. At this time, image exposure is performed after negative charging.

Next, a description will be given of an example in which a rotating drum-shaped photoreceptor is subjected to image exposure using a laser.

FIG. 22(a) is a perspective view showing the relationship between the laser optical system 39 and the image carrier 41. As shown in Figure 2, the CCD
The image formed above is subjected to color correction and dither processing by the image data processing unit 37, and the image data stored in the image memory 38 is emitted from the laser 39a, which is modulated according to the image data by a command from the CPU. The light is reflected and scanned in parallel to the axis of the image carrier 41 by the rotating polygon mirror 39c via the collimator lens 39b, and the fθ lens 3
9d, spot exposure is performed on the image carrier 41 through the reflection mirror 39e. Each wavelength of the laser beam is filtered by filter E3. shown in FIG. By selecting G and R, only each filter is transmitted.

Like a laser, the writing system operates in the main scanning direction (image carrier 41
For the type that scans sequentially in the direction parallel to the axis of i
The end position of the carrier at the beginning of writing can be determined easily and accurately, but in the sub-scanning direction (circumferential direction of the image carrier 41)
In this case, the rotation of the image carrier 41 may result in a maximum scan shift of l. Therefore, as a filter configuration, the first
The shape shown in FIG. 7(b) is stable.

In the filter having the configuration shown in FIG. 17(b), as shown in FIG. 23, an end detection line 41a is provided outside the endmost linear filter in proximity to it, and the laser beam is detected by the photosensor S1. Then, the timing of writing image data by laser light is synchronized so that spot exposure is performed on each of the linear filters R, G, and B. With this method, high accuracy can be easily maintained in both the main scanning direction and the sub-scanning direction. For example, if the main scanning direction does not match the rotation axis of the image carrier 41, the rotation speed of the rotating polygon mirror 39c is changed. Changing the scanning clock pulse or changing the reflection mirror 39e
Accuracy can be maintained by twisting and adjusting.

By exposing dots with a diameter that necessarily includes one unit of the filament or mosaic of the filter layer, or that spans at least two or more units, the tolerance for the deviation of the writing position increases, as shown in Figures 17 (a) to (d). , (al~(
Image exposure can be performed stably for a filter layer having any structure of EL.

In addition to this, in order to achieve stable dot exposure, it is preferable to use an image forming method in which each image of the input image is binarized to represent the gradation in a condensed manner, as described below. Such methods include, for example, the density pattern method shown in FIG.
The dither method shown in Figure 5 is known. Since the unit matrix includes multiple filters of the same color, even if there is a slight positional shift in writing, there will be no problem with re-image reproduction because reproduction is performed using multiple filters of the same color. .

Furthermore, if dot exposure with a diameter that necessarily includes a filter unit is used, it becomes even more stable.

The density pattern method shown in FIG.
sla is an input image, and 2a is a method for converting one pixel with an l tone into a pixel with multiple binarizations, and 2a is a method of extracting a pixel 5a having a representative density value from the matrix of the input image 1a and converting it. This is a sample to be processed, and 3a is an MXN reference density matrix for binarizing this sample.
4a is a pattern obtained as a result of binarizing the sample 2a by comparing it with the reference density matrix 3a.

The dithering method shown in FIG. 25 is a method of converting one pixel with gradation of an input image into one pixel with binary gradation.

1b is an input image, 2b is an example of a specific MXN pixel matrix of the input image 1b, which is a sample for binarization processing, and 3b is an MXN pixel matrix for binarizing this sample.
4b is a pattern obtained by binarizing the sample 2b by comparison with the reference density matrix 3b.

As described above, in the conventional multicolor image forming apparatus, data in the form of color separation of input color image information is
The data can be compared with a reference signal read from the memory, binarized, and recorded based on the obtained data.

For example, when using a striated filter layer having the structure shown in FIG. 17(a), as shown in FIG.
1 consisting of 4 pixels in the sub-scanning direction and 8 pixels in the main scanning direction.
A 2×8 matrix (each image data for day, G, and R is a 4×8 matrix) is used.

In order to ensure that writing is performed on each filter section, the position in the main scanning direction is determined using the same edge detection line 41 as described above.
By the detection of a, the position in the sub-scanning direction is determined by providing a filter detection line 41b in contact with the end detection line 41a (in this example, it is provided on the extension of the tip of the G filter), and using a photo sensor. Each step is performed by detecting laser light in S2.

When writing to the matrix, a concentrated dither matrix is used for the matrix, and writing is performed in the order of spreading from the center of each matrix to the periphery so that image reproduction will not be affected even if a slight positional shift occurs. It is preferable to do this. In a distributed dither matrix in which dark values are arranged in a dispersed manner, a slight positional shift in dot exposure will affect other filter sections and have a large impact on image reproduction, so a concentrated dither matrix is not recommended. It is preferable to use The same applies to the density pattern method.

FIG. 27 shows an example in which a plurality of dot exposures are carried out using a matrix as described above, using a linear filter layer having the structure of No. 17 Kaiyama). In this example, an 8x6 matrix (the image data corresponding to each color is an 8x2 matrix)
I am by. In this case, a filter detection line is not required.

When using a filter layer with a mosaic structure, it is preferable to use a structure with no unevenness in the main scanning direction as shown in FIG. It is preferable to perform matrix writing consisting of scanning and sub-scanning.

The arrangement of the end detection line and filter detection line in this case is illustrated in FIG. In this example, the B filter is detected and written by the detection of the end detection line 41a and the detection of the filter detection line 41b.

For example, a 4×4 concentrated dither matrix is used for writing.

If the writing system passes through multiple filters, it is necessary to match the color data to the color filter to be written.

In this case, accuracy in the main scanning and sub-scanning directions is required to be at a level that matches the color filter.

Exposure spectra B, Q, R of the writing system in the present invention
are set so that the light passes only through the B, G, and R filters on the image carrier.

With this setting, the specific exposure light corresponding to the specific color is transmitted only through the specific filter section, so that the exposure spot diameter on the image carrier can be performed without being limited by the filter width. That is, the exposure spot diameter is set to a size that allows at least one specific color filter to enter or straddle the area. Alternatively, an image is expressed using a plurality of filters of the same color using dither or density patterns. Such positioning can be performed extremely easily. In other words, it means that the unit of image expression is performed using a plurality of filters of the same color. In addition, it is possible to make the mosaic period width correspond to the writing density and not only perform spot exposure that is larger than the line shape of the filter or the periodic width of the mosaic, but also perform exposure with a writing density that is rougher than the periodic width of the mosaic. Furthermore, depending on the exposure system, it is not limited to the dither matrix, and pulse width modulation, intensity modulation, or a combination thereof can be employed. The size of each filter corresponds to the writing system, and the color repetition width (1 in Figure 17) is 10 to 500.
It is preferable to set it to μm. The smaller the filter size is, the better the writing density will be, which is preferable, but if the width of one filter is equal to or smaller than the particle size of the toner particles, it will be difficult to manufacture. Further, it is preferable that the size of the filter be equal to or larger than that, since if the size of the filter becomes too large, the resolution and color mixing properties of the image will deteriorate and the image quality will tend to deteriorate. Particularly preferably, it is 1 to 4 times the period l of the filter. In addition, the writing spot diameter of each color is the writing density of each color (dat/m
It is preferably 1.0 to 5 times the reciprocal of m).

Next, a specific example carried out with the configuration described above will be described using the apparatus shown in FIGS. 2 and 3.

An image forming apparatus shown in FIG. 2 was used. A laser optical system 39 shown in FIG. 22(a) is used as a writing system.

However, the image carrier 41 has a stainless steel base, and has a 60 μm thick Se, Te+O surface layer exposed to a 2 μm thick S layer.
e. Tex. on the 5e-Te photosensitive layer long-wavelength sensitized with a thickness of 20. CRM Fig. 14(d) and Fig. 17(d)
) The size of one filter that transmits light in blue, green, and red is 33 μm x 50 crm (j+
= 100 μm, it = 100 μm), and its circumferential speed was 100 m/sec. While uniformly exposing the image carrier 41 with the lamp 4A of the primary charger 4, the DC scorotron corona discharger 4
The image carrier 41 was charged to have a surface potential of -2000V.

Next, a secondary charger 5 consisting of a scorotron corona discharger having an alternating current component raises the surface potential of the image carrier 41 to +300cm.
It was charged so that Next, image exposure was performed using digital signals. Each filter transmits only each laser beam.

Each yellow (Y), magenta (M), and cyan (C) image data is transferred to E3. G, R mosaic filter (first
Figure 7 (d), the period of the mosaic is 100 μm x 10100
Size of both systems in u is 100 p m x 100 p m
Writing was performed with a 4×4 dither matrix unit matrix size of 4008 m×400 μm.

The writing density of the laser is 10 dots/1 square, and the writing diameter is 200 μm/dot. Its shape is approximately square.0 In the present invention, the writing diameter is 1.0, which is the reciprocal of the writing density.
The size is set to about 0 to 5 times, and this is set to ensure that writing to the filter section is performed.

The writing timing is determined by detecting a specific filter using the filter detection line, using the detection of the edge detection line by the laser beam as a signal, and shifting the writing timing of each image data in the main scanning direction, that is, at the edge of each filter. It was written independently from YSM and C in correspondence with (see Fig. 28).

In this embodiment, since the writing system is larger than the reciprocal of the writing density, complete synchronization with the filter position cannot be achieved (but it has the advantage that information can always be written to a specific filter. Also, the dither matrix is a centralized type, A distributed type or a variation thereof can also be used.Of course, intensity modulation or a combination of intensity modulation and a dither matrix can also be preferably used.Also, a density pattern method can also be preferably used.

An electrostatic image with a contrast of 350 V in absolute value was then formed by uniform exposure through a blue filter. This potential contrast was about 1/3 of that when a transparent insulating layer was used. This electrostatic image was developed using a developing device 17Y as shown in FIG.

In developing device 17Y, magnetite is 70wt% in the resin.
Contained dispersedly. Average particle size is 30μm, magnetization is 30Cmu
/g % A developer consisting of a carrier having a resistivity of 10"Ω1 or more; and a positively charged non-magnetic toner having an average particle size of 10 μm, which is prepared by adding 1 part of benzidine derivative 10ffi as a yellow pigment to a styrene-acrylic resin and other charge control agents. It was used under the conditions that the toner ratio in the agent was 20-t%.The outer diameter of the developing sleeve 7 was 301 m, and the number of rotations was 11.
00rp, the magnetic flux density of N and S magnetic poles of M1 stone body 43 is 9
00 Gauss, rotation speed 11000 rpm, developer layer thickness in the developing area 0.7 gauss, developing sleeve 7 and image carrier 41
Gap between 1. Otm and +200 for developing sleeve 7.
V(7) DC voltage and 2.5 kllz, 2000V (
7) AC voltage superimposed voltage (amplitude of construction wave is 2 x & plane OV
) was applied under non-contact development conditions.

Incidentally, while the electrostatic image was being developed by the developing device 17Y, the other developing devices 17M 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 the same polarity to the electrostatic image on the developing sleeve (i.e., the opposite polarity to the toner charge).
This is achieved by applying a DC bias voltage of
Among these, it is preferable to apply a DC bias voltage.

In addition, the driving of the developing device was stopped during non-developing time. Developer 1
Since 7M and 17C are also developed under the same non-contact development conditions as developer +7Y, the developer layer on the developing sleeve is removed and does not need to be present. The developing device 17M uses a developer in which the toner in the developing device 17Y is changed to a toner containing polytan dust phosphoric acid as a magenta pigment instead of a yellow pigment, and the developing device 17C uses the same toner. A developer was used in which the cyan pigment was changed to a toner containing a copper phthalocyanine derivative. Of course, color toners based on other pigments or dyes can be used, and the order of developing colors can be appropriately determined so as to obtain clear color images. In particular, the order in which the colors are developed needs to be carefully determined because it may be related to the sharpness of the color image and the potential contrast during exposure to be obtained.

After the surface of the image carrier 41 developed by the developer 17Y was recharged to a surface potential of +350 V by a scorotron corona charger, green exposure was performed.

The position of the electrostatic image obtained by this is the background part + 350
It was -5OV with respect to v. This electrostatic image was transferred to a developing sleeve with a DC component of +250V and an AC component of 2.5K Il.
z, developing device 17Y except that a voltage of 2000 V was applied.
The film was developed using the developing device 17M under the same conditions as in .

Similarly, the scorotron charger increases the surface potential to +400
After recharging to V, red exposure was performed.

As a result, an electrostatic image of -50V is formed with respect to the background area of -400V, and this electrostatic image is transferred to the developing sleeve with a DC component of -400V.
300V, AC component 2.5 kHz, 2000V (7
) Development was carried out in the developing device 17C under the same conditions as in the developing device 17Y except that a voltage was applied.

When this third development is performed and a three-color image is formed on the image carrier 41, the corona discharger 21 is activated, thereby making it easier to transfer the color image. The image was transferred onto a copy paper 8 by a transfer device 9, separated by a separator 10, and fixed by a heat roller fixed fixer 13.

The image carrier 41 to which the color image has been transferred is charged with a static eliminator 11 while being irradiated with white light or infrared light, residual toner is removed from the surface by a cleaning blade of a cleaning device 12, and a color image is formed. When the surface passes through the cleaning device 12, one cycle of color image recording is completely completed.

The color image recorded in the above manner was extremely clear, with no color mixing not only in areas where the color toners were loosely adhered to each other, but also in areas where they were closely adhered.

In addition to the above-described development method, as a modification of the development method without rubbing the photoconductor, only the toner from the composite developer is taken out onto the developer transport carrier, and one component of the toner is produced in an alternating electric field. Method of developing (Japanese Patent Application Laid-Open No. 59-4256
No. 5, 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 Application Laid-open No. 56-125753), a method in which a similar control electrode is provided. It goes without saying that the method of developing with a two-component developer in an alternating electric field (Japanese Patent Application No. 58-97973) is also included in the multicolor image forming method of 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-
When the adhesive transfer method described in Japanese Patent No. 22763 is used, transfer can be performed without considering the polarity of the toner. Further, the layer structure of the photoreceptor described above includes an insulating layer, a photoreceptor layer,
It is also possible to adopt a structure in which development is performed from the insulating layer side by providing a conductive layer and a filter, providing primary and secondary charging from the insulating layer side, and image exposure from the filter side (Japanese Patent Application No. 59-1982).
9547).

In addition, although the above explanation has all been about an example of a color printer using so-called three-color separation image data and three primary color toners, the embodiments of the present invention are not limited to this.
It can be widely used in various multicolor image recording devices, color photo printers, etc.

Real】l” shadow In this example, LC3 is used for image exposure.

The structure of this LC3 uses white or B, G, and R fluorescent light sources. When a white light source is used, a BSGSR filter is provided to make it monochromatic. The filters on the image carrier were such that writing was performed only in the B, G, and R filter portions when the image was exposed through the liquid crystal shutter.

The focusing Rondo lens array provided between the image carrier and the liquid crystal shutter panel is set so that its focal point is offset from the surface of the image carrier, as described above.

Alternatively, the diameter of exposure of each unit segment onto the image carrier is approximately equal to or larger than the reciprocal of the filter period. By doing so, when a filter layer as shown in FIGS. 17(a) and 17(b) is used, the permissible range of setting accuracy of the liquid crystal shutter is widened.

Of course, the same applies to filter shapes as shown in FIG. 17 (C1, (d)).

The image forming apparatus shown in FIG. 2 was used. However, the above LC3 was used for the writing system.

FIG. 29(a) is an enlarged sectional view of the main part of LC3139 (7),
FIG. 30 is a schematic perspective view showing the positional relationship between the LC5139 and the image carrier 41. In Fig. 30, LCSR monochromatic fluorescent lamp light source, 139b is a liquid crystal shutter panel, tas
139c is a liquid crystal shutter segment, 139d is a focusing Rondo lens array, and 139e is a driving IC for driving each liquid crystal shutter segment 139C.

Using such an apparatus, image formation was performed in the following manner.

The image carrier 41 is made of ASxS with a thickness of 40 μm on a Ni substrate.
On the a-z photosensitive layer, one filter having the structure shown in FIG. 14(al) and FIG. 17(d) having a thickness of 15 μm and transmitting light in blue, green, and red is placed, and the size of the filter is 30×30 μm.
1 filter period 1 + = 90 μm, (l z = 6
It has an insulating layer of 0#m, and its circumferential speed is 5
Qm/sec. A primary charger 4 is attached to this image carrier 41.
While performing uniform exposure with the lamp 4A, the surface potential of the image carrier 41 is set to - by the DC scorotron corona discharger 2■.
It was charged to 2000V. Next, the image carrier 41 was charged with a secondary charger 5 consisting of a scorotron corona discharger having an AC component so that the surface potential of the image carrier 41 was 1300V. Next, each filter subjected to image exposure using a digital signal transmits specific light.

Each Y, M, and C image data was written independently, each writing density was 10 dos)/mm, and the writing width was 100 μ.
m/dot. The writing spot diameter is 150 μm, which is 2 to 3 times the width of one filter period.

As for the writing timing, each image data was written in correspondence with a 2×2 distributed dither matrix without using a specific filter detection means using a filter detection line.

FIG. 31 schematically shows a state in which writing is performed using green light, and the circular broken line indicates the exposure range of one substrate. One spot diameter spans multiple filters of the same color.

Hereinafter, in the same manner as in Example I, exposure with specific light,
A color image was formed by repeating development and recharging. The color image obtained was of good quality, as in Example 1 above.

As a writing system, in addition to the above-mentioned laser and LC3,
It is possible to use a device having a function similar to LC3, such as LISA, CRT, or OFT, which uses magnetic polarization. When OFT is used, it is possible to obtain light of different wavelengths with different spectral characteristics by providing a filter on the fiber plate or providing phosphors with different wavelength ranges.

Daitoyomasu Main Figure 32 (al is flat tube to R, B, Gj 1 color CRT,
Image exposure is performed by forming color images displayed by the R-CRT, B-CRT, and G-CRT onto the image carrier 4N using the lens Le.

This corresponds to the application of a kinereco device, and B.
This device is basically the same as the device shown in FIG. 22, which uses G and R lasers.

Figure 32 (bl is the flat color CRT of the mold, the three colors are painted)
Image exposure is performed by forming a displayed color image onto a photoreceptor using a lens. Image exposure performs intensity modulation and assigns 16 bits to 1 dot25
Six gradations were recorded.

The image forming method is the same as in Example 1.

3IN4 The image forming apparatus shown in FIG. 33 sequentially forms toner images of one color with one image exposure and one rotation of the image carrier 41, and is used by switching.

For example, in the multicolor image shown in FIG. 2, exposure is performed using an optical system equipped with blue, red, and green light, and the charger 5 is used to make the surface potential of the image carrier 41 uniform after development. Different from the forming device. Similar to the multicolor image forming apparatus shown in FIG. 2, this multicolor image forming apparatus also performs the same image forming operation as described for FIG. A monochromatic image can be formed. That is, for example, when forming a three-color image, the image carrier 41
After charging by the charger 4 and making the surface potential uniform by the charger 5, the surface of the image carrier 41 is exposed to blue light, and the developing device 7Y develops the potential pattern formed thereby to produce a yellow color. Form a toner image. This toner image passes through the developing devices 17M, 17C, and 17K, the pre-transfer lamp 22, the transfer device 9, the separator 10, the cleaning device 12, and the charger 4 without being affected. When the image carrier 41 on which the toner image has been formed reaches the position of the charger 5, it receives corona discharge to make the surface potential uniform, and is exposed to green light, forming a potential hole turn. Subsequently, this is developed by the developing device 17M to form a magenta toner image. Similarly, a potential pattern is formed by exposure to red light and development is performed by the developing device 17C to obtain a three-color toner image.

When forming a monochromatic image, a potential pattern is formed on the surface of the image carrier 41 by simultaneous exposure of blue, green, and red light to the charged and image-exposed image carrier 41, and the potential pattern is transferred to the developing device 17C. Develop one or a combination of 17.
A monochromatic image with sufficient image density and high resolution can be obtained (second
Also in the image forming apparatus shown in the figure, in the case of LC3, exposure can be performed with white light without passing through a filter. ). This multicolor image forming apparatus has a simple configuration that is almost the same as a monochrome printer except for the increased number of developing devices, and has the advantage of being smaller and lower in cost.

The same reference numerals in FIG. 33 and FIG. 2 indicate the same functional members.

In this case, in order to make the exposure device more compact, the 22nd
The exposure apparatuses shown in FIG. 29(b), FIG. 32(b), and (C) are preferably used.

In FIG. 22('b), the entrance path to the polygon is shared by a microink mirror. 29th Kaizan) B, G
, R monochromatic fluorescent lamps are switched and used according to the image data. In place of this, a white light source is used to insert the G.
, R filters are switched, the incident path in FIG. 32(C) is shared by a half-mirror HM as in FIG. 24(b). Instead of this, a white light CRT is used and inserted B.
The G and R filters may be switched.

Scraping Team 1 According to the present invention, a clear color image without color shift or uneven development can be obtained at high speed, the device can be made smaller and less expensive, and the memory capacity of the reading device can be significantly reduced.

In this example, an image signal is obtained by photoelectrically converting color-separated light obtained by optically scanning a document, and based on the image signal, an image is written in correspondence to a filter section on an image carrier to create an electrostatic image. In a color image forming apparatus that repeats the step of developing the electrostatic image to form a toner image after formation and superimposing each color toner image on the image forming body, preferably A color image forming apparatus comprising a control means for synchronizing writing on the document and optical scanning of the document.

Image formation is performed by this.

The above configuration will be described in detail below with reference to illustrated examples.

In FIGS. 2 and 33, 32 is a document holding plate that brings the document 31 into close contact with the document table; 34 is a reflection mirror that reflects light L1 when the document 31 is scanned and exposed using the exposure lamp 33 as a light source; The light reflected by the group of reflection mirrors is focused by a lens 35 and irradiated onto a one-dimensional color image sensor 36, where it is converted into an electrical signal. Note that the arrow indicates the direction in which the light source 33 and the mirror group 34 are moved for scanning. The light is transmitted to the surface of the CCD image sensor 36 having the same structure. The light is exposed to sensor elements 51 disposed one-dimensionally and densely on the CCD image sensor 36 and photoelectrically converted, and the electrical signal obtained by the photoelectric conversion corresponds to the pulse frequency of the transfer gate pulse 54. It is driven by the two-phase driving pulses 53 of φ8 and φ2 at high speeds, and is main-scanned in the direction of the arrow X within the transfer section (COD shift register) 55, and is outputted to the output 56. The output signal obtained here is input to the image data processing section 37 shown in FIGS. 2 and 33, where color correction and image processing are performed. This can be used as image memory 3 if necessary.
8 is stored. Modulation of the laser beam is performed based on the image data obtained in this manner.

Thus, the laser beam modulated by the laser optical system 39 optically scans the image carrier 41, and an image is formed according to the above-described procedure.

Incidentally, the image exposure is not limited to the dot exposure using a laser beam as described above, but as described above, for example, an LED, a CRT, an OFT, a LIS/l'Lc, etc.
s or one obtained using an optical fiber transmission body. The image carrier 41 can also be a recording device that can take a flat state like a belt.

When the image carrier is in a planar state, elements such as LEDs, LC3SL ISAs, OFTs, etc. corresponding to the parts of each component to be color-separated, such as a color separation filter, are arranged in a planar manner opposite to the image carrier. By means of control means that drive and control the group,
selectively operating the above-mentioned element group based on image data, and forming an electrostatic latent image on a flat surface of a stationary image carrier by simultaneous exposure without optical scanning; Can be done.

Next, the above image data processing system will be explained.

The output signal from the CCD image sensor 36 is processed by the image forming system shown in FIG. 35 to form an image.

In FIG. 35, the recording device, dot pattern memory, and image forming process are controlled and driven by control signals from the central processing unit (CPU). For example, the exposure system (lamp 33, mirror 34 and lens 35), a COD image sensor 36, which is a type of color scanner, reads B, G, and R color information in the horizontal direction of the document 31, and outputs an analog video signal. This signal is A
/D conversion After the conversion, shading correction is performed to remove distortion caused by the axis information optical system, etc., and the data is temporarily input to a buffer memory to make G and R correspond to the same image position each day. Next, the day, G, and R signals from the buffer memory are subjected to complementary color conversion to Y, M, and C, and gradation correction is performed.

The filters used for the photoreceptor are B and G as shown in Figure 17.
, R, Y, M
, C are separated into image data. On the other hand, if it is composed of 411 types of filters such as G, R, Y, M, C
A black component is extracted (OCR) from each data and separated into a chromatic color component and an achromatic color component. Here, the chromatic color components Y, M, and C are color corrected and tone corrected together with the black component (BK). Next, pattern generator (PC)
is input. Here, for example, after being changed into a digital dot pattern signal based on the dither method, it is normally stored in a page memory for each color, but in this method, the dot pattern signal is not stored in the page memory and is only used as a buffer. The image is output to the recording device via the line memory, and an image is formed by writing almost in synchronization with reading.

In this image forming process, since reading and writing are performed synchronously, high-speed recording is possible and the page memory can be saved.

As the printer, the one shown in FIG. 2 or FIG. 33, which has already been explained, is used. The image carrier also detects the photoreceptor potential, drum environment (temperature, humidity, fatigue), forms a reference image, and determines charging, writing light intensity, image processing conditions (darkness value, etc.) from its developability. It is preferable to control the developing device to stabilize the image.

This has the advantage that color image information transmitted dot-sequentially or line-sequentially by facsimile or the like or stored in a page memory can be read onto the image carrier in real time.

In this way, it is possible to stably obtain high-quality images that are faithful to the original and have good gradation.

Of course, by storing the image data in the memory, image formation can be performed later at any time as needed, based on the stored image information, without requiring a document.

Although the above examples are all about the formation of multicolor images, the present invention can also be applied to the formation of monochrome images. For example, by repeatedly using the same developing device using the image forming device shown in FIG. 33, or by sequentially performing only image formation, a specific developing device is used to convert a full-color original image into a monochromatic (for example, black and white) image. images can be formed. Furthermore, the following image formation is also possible. For example, a multicolor image can easily and conveniently incorporate a large amount of information into a single image, such as a graph in which different colors are displayed depending on a plurality of factors that affect a given characteristic. However, if only a specific factor among these factors is of interest, graphs relating to other factors become obtrusive. In such a case, it is possible to extract and reproduce only the graph of a specific color from the above graph. In this case, exposure is performed using an exposure wavelength corresponding to the specific color, and development is performed using a specific developing device. That is, it is sufficient to form an image with only one exposure and one development.

Effects of the Invention As explained above, the present invention forms an electrostatic latent image by selectively exposing the image carrier with different exposure wavelengths corresponding to the color separation functional portions, and then Since the electrostatic latent image is developed to form an image without exposure, the following effects can be achieved.

An electrostatic latent image is formed independently for each color separation function part, and this electrostatic latent image is developed, so it is not affected by other types of color separation function parts (and does not cause color turbidity). Moreover, it can be advantageously adapted to the line-sequential image data transfer/storage system.In addition, there is no need to align various images, unlike the conventional electrophotographic color system with a transfer drum. It is possible to achieve smaller size, higher speed, and improved reliability.Furthermore, the obtained image has no color shift and is of high quality with excellent reproducibility.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention.
], [7] and [8] are process flow diagrams showing the image forming process, Figure 2 is an internal schematic diagram of the image forming apparatus, Figure 3 is a cross-sectional view of the developing device, and Figure 4 is the spectral transmittance of the filter. FIG. 5 is a schematic plan view showing an example of an exposure spot for a mosaic filter; FIGS. 6 and 7 are graphs showing the spectral transmittance of the filter and the spectral distribution of exposure light; FIG. 8; FIG. 9 is a graph of data obtained when a one-component developer is used; FIG. 10 is a graph showing the relationship between the amplitude and frequency of AC bias when a one-component developer is used; FIG. 11; 12th
The figure is a graph of data obtained when using a two-component developer. Figure 13 is a graph showing the relationship between AC bias amplitude and frequency when a two-component developer is used. Figure 14 (a) ,
(b), (C1 and fdl are cross-sectional views of each photoreceptor, 15th
16 and 16 are sectional views of other photoreceptors, respectively.
Figures 8 (a), (bl, (C), (d) and (e) are plan views showing the arrangement of filters on the surface of the photoreceptor; Figure 19 is a graph showing the spectral transmittance of other filters; Figure 20 21 and 21 are respectively sectional views of other photoreceptors, FIGS. 22(a) and (b) are schematic perspective views showing the positional relationship between the laser optical system and the image carrier, and FIG. 23 is the exposure spot. FIG. 24 is a plan view showing the method of determining the position of the input image; FIG. 24 is a diagram showing the step of binarizing the input image using the density pattern method; FIG. 26, 27, and 28 are plan views showing other methods of determining the position of the exposure spot in image exposure, respectively; The figure is a schematic perspective view showing the positional relationship between the liquid crystal shutter and the image carrier, FIG. 31 is a schematic plan view showing another example of exposure spots for the mosaic filter, and FIGS. 33 is an internal schematic diagram of another image forming apparatus, FIG. 34 is an enlarged schematic diagram showing the structure of a COD image sensor, FIG. 35 is a block diagram showing the image forming system. In addition, in the symbols shown in the drawing, 1-・-・--1---・Conductive substrate 2・--
−−−1−−・−Photoconductive layer 3−・−・−・・−・・−・
Insulating layer 3a--1 to-1...Filter layer 4.5--
----Charger 17Y, 17M, 17C, 1
7 ---------Developer 36---- CCD image sensor 37--
・・・・Image data processing section 38−・・・・・−・−
・Image memory 39-------------Laser optical system 139-------LCD shutter 41--
−・−・−・−・・Photosensitive drum (image carrier) R−
・−・−・−・−・Red filter G−・・−・−−1−−−−Green filter B−−−−
−−−−・−・・−Blue filter L, −・−・・・・
−・−Red light, −・−・−・・・・・Blue light Lc−−−−・−・・−・Green light TY−・・−−−−−−・Yellow toner TM−
−−−・・・−1−−−−・Magenta Toner D・−−−
−−1・・−−−11 Developer T−−−−−・−・−・−
It's toner. Agent Patent Attorney Hiroshi Aisaka Figure 2 Figure 3 4m Wave + (nm) Figure 5 Figure 6'' Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 00゛5EAo゛1゛° 3 (K-/+nm] Fig. 12 01 EAC [K, 7 ml Fig. 13 0 + 2 t t,, □) Fig. 15 Fig. 16 Fig. 18 Fig. 19 Fig. 20 Fig. 21 Fig. 23 26 Garden Figure 27 Figure 30 Figure 31 (b)

Claims (1)

[Scope of Claims] 1. An electrostatic latent image is formed by selectively exposing an image carrier on which a color separation function part is arranged at different exposure wavelengths corresponding to the color separation function part. and a subsequent step of developing the electrostatic latent image without exposure. 2. Opposing the image carrier on which the color separation function section is arranged, an exposure means for selectively exposing light at different exposure wavelengths corresponding to the color separation function section, and a development means are arranged, and the development means is arranged to convert image data into image data. An image forming apparatus comprising a control means for controlling an exposure means for performing the selective exposure based on the selective exposure.