JPS62201477A - Image forming method and its device - Google Patents

Abstract

PURPOSE:To form rapidly and simply an excellent and polychromatic image by forming a process for forming an electrostatic latent image based on selective exposure and a process for uniformly exposing an image carrier by a specific light beam, forming a potential pattern in each color decomposing function part and executing development. CONSTITUTION:While being rotated as necessary, a photosensitive drum 41 is electrostatically charged to its whole surface by a charging electrode 4 under the projecting status from a light source 4A. While being projected by a laser beam L or an image exposing light L composed by blue, green and red images from the back of the succeeding electrode 5 and receiving corona discharge having a reverse code against AC or the electrode, the drum 11 is exposed by exposing light L based upon image data through respective filters to end the primary latent image forming process. Subsequently, the drum 41 is uniformly exposed by blue light obtained by the combination of a light source 6B and a blue filter FB for the light source and the latent image is developed by a developing sleeve 7Y in a developing device 17Y. Thus, an excellent and polychromatic image can be rapidly and simply formed.

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 device becomes larger and costs increase, and when a single writing system is used, latent image formation and development processes are repeated multiple times. 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, no study has been made regarding the image data writing method, the potential pattern forming method, the filter shape, the spectral characteristics of the writing system and the filter, and the developing conditions for developing with each color toner. Therefore, if image formation based on the above-mentioned digital signals is applied to the above-mentioned image forming apparatus, image color shift, disturbance of l/ner images, decrease in image density, lack of precision between the filter and image data writing, etc. cannot be avoided.

C1 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.

21 Structure of the Invention The first aspect of the present invention is to selectively expose to light corresponding to each color separation functional portion of an image carrier having a surface insulating layer and having a color separation function within the plane. forming an electrostatic latent image by forming an electrostatic latent image; and thereafter, uniformly exposing the image carrier with specific light to form a potential pattern in each of the color separation functional parts, and developing the image. Regarding the method.

A second aspect of the present invention is to selectively expose a predetermined color separation functional portion of the image carrier, facing the image carrier having a surface insulating layer and having a color separation function in the plane. The present invention relates to an image forming apparatus which includes an exposure means for selectively performing exposure, a uniform exposure means using specific light, and a developing means, and has a control means for controlling the exposure means for selectively performing 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 uniform exposure and development in accordance with the type of filter, at least two
The development in the subsequent steps is performed under conditions in which the developer layer on the developing device side does not substantially come into contact with the image carrier.

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

(1) In the developing process, 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 step is adopted in which the latent image is developed using a -component developer, and in this developing step, the amplitude of the alternating current component of the developing bias is set to VAC (V), the frequency is set to f (Hz), and the said image is The gap between the carrier and the developer transport body that transports the developer is d.
(am), 0.2≦vAc/(d・dry)≦1
．． 6. Must be satisfied.

(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 step, 0.2≦Vac/(d-su)((Vac/d)-1500)/f≦1.0 should be satisfied.

(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 all the filters.

(v) Alternatively, the light used for image exposure is one that passes through a specific filter.

(vi) As the optical scanning exposure means, laser, LISA
.

Liquid crystal shutter (LC3), light emitting diode (LED),
CRT and optical fiber tube (OFT) are preferred.

(vi) In the case of a plurality of image exposure means that perform image exposure at the same time as charging, a combining means using a mirror optical system can be used.

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

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

(x) Alternatively, image exposure is performed by asynchronously filling the filter position on the image carrier with image data.

(xi) Image exposure is performed by spot exposure, and spot exposure is performed over a plurality of filters of the same color.

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

(xiii) Instead of the plurality of types of filters mentioned above, a photoconductive layer having a color separation function described in Japanese Patent Application No. 59-201085 is used.

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 of all, in the explanation, we will introduce red light, which passes through a color separation filter (a filter that passes only light in the infrared wavelength range and a specific wavelength range, and transmits only red light, green light, and blue light together with infrared light), respectively. 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, a positive charge is generated on the surface of the insulating layer 3. A negative charge is induced at the interface.

Next, as shown in FIG. 1 [2], alternating current or negative discharge is applied by the charger 5, and while erasing the charge on the surface of the insulating layer 3, a semiconductor laser (
780na+) in a manner that corresponds to each filter section. Here, for example, a case will be described in which exposure corresponding to image data of a red image is applied only to the red filter section. The creation of image data will be described in detail later, but yellow image data corresponds to the blue (B) filter section, magenta image data corresponds to the green (G) filter section, and cyan image data corresponds to the red (R) filter section. shall be written.

The laser beam is exposed only to the red filter part R of the insulating layer 3 and makes the photoconductive layer 2 below it conductive. It also erases charges.

On the other hand, since the green 3G and blue filter parts 3B are not irradiated with laser light, some of the insulating layers are positively charged and the photoconductive layer 2 is
The negative charge remains.

The description of the process shown in FIG. 1 [2] above is for the case where image exposure is performed using a semiconductor laser (780 nm) that can pass through all the filters.

When image exposure is performed using light in the wavelength range corresponding to filters R, G, and B, the procedure is as follows.

Following Fig. 1 [1], as shown in Fig. 1 [2], the charger 5
Based on the image data from the back of the charger while erasing the charge on the surface of the insulating layer 3 by applying alternating current or negative discharge,
A liquid crystal shutter (L C
S) to expose each filter portion to light. For example, in the case of image data of a red image, red light exposure LR is used to attach yellow toner and magenta toner.
Explain the case where . The creation of image data will be detailed later, but yellow image data is sent to the blue (B) filter section, magenta image data is sent to the green (G) filter section,
It is assumed that cyan image data is written in correspondence with each red (R) filter section.

Since the image exposure light makes the photoconductive layer 2 under the red filter section R of the insulating layer 3 conductive, it erases the positive charges on the insulating layer 3 and also the charges in the photoconductive layer 2 in the same filter section. . On the other hand, since the green filter section 3G and the blue filter section 3B do not transmit red light, some positive charges on the insulating layer and negative charges on the photoconductive layer 2 remain as they are.

The above corresponds to the first latent image formation, but at this stage,
Not only the red filter 8 portion from which charges have been erased, but also the portions 3G and 3B where charges remain have the same potential on the surface of the insulating layer, and therefore do not function as an electrostatic image. Figure 1 [2]
In this example, the potential after charging is approximately zero, but it may be charged to a negative level.

Next, if the potential is not flattened, the potential is flattened by recharging as necessary, and as shown in FIG. 1 [3],
When uniform exposure is given to light of the same color as one color in the filter contained in the insulating layer 3, for example, blue light obtained by the light source 6B and the blue filter F, the light below the filter 8 that transmits the blue light The conductive layer 2 becomes conductive, and a portion of the negative charge of the photoconductive layer 2 and the charge of the conductive substrate 1 in this area are neutralized, and a potential pattern is generated only on the surface of the filter B. No change occurs in the G and R portions that do not transmit blue light. Then, when the charge image on the filter B section is developed with a developer containing negatively charged yellow toner TY, the toner adheres only to the insulating layer B section, which has a potential, and development is performed (see Fig. 1).
4)).

Next, the generated potential difference should be erased (after being charged with the charger 15 as shown in Fig. 1 [5], it will emit a green light as shown in Fig. 1 [6], and when uniform exposure is given with A latent image is formed in the green filter portion G as in the case of full-surface exposure to light.If this is developed with magenta toner TM as shown in FIG. 1 [7], the magenta toner TM is formed only in the filter G portion. If charging is not performed using the charger 15, a potential pattern will remain and the magenta toner T will adhere.
M adheres and color mixture occurs, which is not preferable.

Subsequently, as shown in FIG. 1 (8), after being charged again in the same way, uniform exposure to red light is applied, but no potential pattern is formed on the red filter portion R, and even after development with cyan toner, cyan is not formed. No toner adhesion occurs.

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 the uniform exposure and the color toner do not need to be in a complementary color relationship, and it is sufficient that the image data and the color toner correspond to each other in order to perform faithful color reproduction.

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

In principle, the present invention uses additive color mixing in which toner adheres to each filter part, but subtractive color mixing is also realized because toner spreads during development or during transfer, separation, and fixing processes. As a result, high image density is achieved.

Margin below, continued on next page.

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 uniform exposure and color toner, or by changing the combination of image data and a filter for writing the image data.

In addition, in the above explanation, the spectral characteristics of the specific light for uniform exposure are those of the same color as the filters of the photoreceptor, green (G), blue (B), and red (R). The characteristics are not limited to G, B, and H. 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 uniform exposure to a specific light, for example, a blue filter. When a potential pattern is formed, the thickness is approximately 500 nm or less.
An example is one in which uniform exposure is performed using a material having broad spectral characteristics including wavelengths of 00 nm 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, after charging the multicolor image forming photoreceptor and applying image exposure using each image data in accordance with each filter section, Generates a potential pattern in only one type of filter. The process of applying uniform exposure and developing is repeated depending on the number of types of filters.

That is, a fine color separation filter is placed on the photoreceptor, and after image exposure (step [2] in Figure 1), uniform exposure (
Steps (steps [3] and [6] in Figure 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 Figure 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 stripes or mosaics on a photosensitive layer, and image exposure is applied to the stripes or mosaic. , forming a primary latent image in accordance with each color separation image data on the photosensitive layer below each filter, and then uniformly exposing the photoreceptor to light of a specific color (in this example, the same color as the filter); By this, a second latent image is formed only on the filter of the color, and a potential pattern corresponding to the light intensity in the first latent image forming process is formed. and,
A multicolor image is formed on the photoconductor by developing it with color toner corresponding to the color of the image data, and repeating the same operation for each separated image, and then a multicolor image is formed on the transfer material at once by - times of transfer. can be recorded.

In addition to the image forming method described above, a process in which charging and image exposure are performed separately can be used. This process forms a charge on the photoconductive layer by performing a primary charge followed by a secondary charge of substantially opposite polarity (this process is shown in Figure 1 [1] [2] when there is no image exposure). ), then image exposure is performed, and the resulting potential contrast is smoothed by tertiary charging. (This state is shown again in Figure 1 [2
]. ) Next, the process of uniform exposure to specific light and development is repeated in the same manner as shown in FIG.

In addition, as shown in Japanese Patent Application No. 59-187045, primary charging and simultaneous image exposure or -order charging can be carried out using a photoconductive layer that does not inject charges into the photoconductive layer due to -order charging. It is also possible to use an image forming method in which the process of uniform exposure to specific light and development is repeated after imagewise exposure is performed, followed by secondary charging of substantially opposite polarity.

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 the figure, reference numeral 41 denotes a photosensitive drum (image carrier) consisting of a photosensitive member having the structure shown in FIG. 1, which rotates in the direction of arrow a during a copying operation. While rotating, the photosensitive drum 41 is irradiated with light by a light source 4A as needed, and the entire surface is charged with a charging electrode 4, and a laser beam or a blue image, a green image, and a red image are emitted from the back of the next electrode 5. Exposure based on the image data is given to each filter while being irradiated with the combined image exposure light and receiving alternating current or corona discharge of the opposite sign to that of the electrode 4, and the first latent image forming step is completed.

Next, the toner is uniformly exposed to blue light obtained by the combination of the light source 6B and the light source blue filter FIl, and developed by the developing sleeve 7Y of the developing device 17Y loaded with yellow toner. Next, after recharging with the charger 15, the light source 6G
, uniform exposure with green light from the green light source filter Fa,
Developed by the developing sleeve 7M of the developing device 17M loaded with magenta toner, recharged by the charger 15, uniformly exposed to red light from the light source 6R1 red light source filters F and 1, and developed by the developing device 17C loaded with cyan toner. Sleeve 7C
A multicolor image is formed on the photoreceptor drum through development. 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, fixed by the fixing device 13, and becomes a completed multicolor copy, which is discharged outside the machine. On the other hand, the photoreceptor drum 41 after the transfer is irradiated with a neutralizing light as necessary, and the static electricity is removed by the neutralizing electrode 11, and the toner remaining on the surface is removed by the cleaning blade 12, and the drum 41 is used again.

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

In the above example of image exposure using laser light, in a panchromatic photoreceptor that has sensitivity up to the infrared region by long wavelength sensitization, the spectral transmittance of the filter is, for example, 4
As shown in Figure (al or (bl), a semiconductor laser is effective as a writing system used in combination with this. In addition, LCS using an infrared exposure light source and LED
can also be used.

In the above example, the B, G, and R filters are designed to be transparent to imagewise exposure and to have high spectral transmittance in the long wavelength range.

In addition to the above, the spectral transmittance of the filter can also be selected as shown in FIG. In this case, the writing system is a half door laser, etc., as well as a Ne-He laser (632,8 nm).
You may use a short wavelength such as In this case, the uniform exposure is
Blue (500n+++ or less), green (600nm or less), and red (600nm or more) are performed in this order.

When using a filter with the spectral transmittance shown in Figure 6, uniform exposure is performed first with blue light (500 nm or less) or infrared light (700 nm or more), and finally with white light or green light (
500 to 600 nm). As the writing system in this case, an LCS or LED having spectral characteristics of 500 to 600 nm can be used.

As mentioned above, it is important for writing to use an exposure system that has a common transmittance for each filter, and the spectral transmittance of the B, G, and R filters and the wavelength of the uniform exposure light are , is not essential to the invention. That is,
The spectral transmittance distribution of each filter is such that the image exposure light commonly passes through each filter depending on the writing system used, and then a potential pattern is selectively applied to each filter part by uniform exposure with specific light. It is necessary that it can be formed.

For example, as shown in FIG. 7, filters B, G, and R are
It is also possible to have no spectral transmittance in the front, green, and red regions, respectively.

On the other hand, when an exposure system having a plurality of different spectral characteristics is used as a writing system, image data corresponding to each spectral characteristic is written only to each predetermined filter section to selectively form a potential pattern. Is required. As such an exposure system, one that provides exposure to blue, green, and red light, or one that provides exposure to different wavelengths, such as color FT, color liquid crystal, etc., is preferably used.

If the filter portion 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 inserted into each unit filter as shown in FIG. 8 (al). Even if the size is larger than the size of the 8th filter, it will not be written to other filters.
In the example in Figure (a), when writing to the B filter section marked with solid diagonal lines, if the area surrounded by the dashed diagonal lines is exposed, it will be written to the R1G filter section and other B filter sections. No writing is done.

In the above example of image exposure using image exposure light that is a combination of blue, green, and red images, in a panchromatic photoreceptor, the spectral transmittance of the filter is as shown in FIG. 4(b), for example. As a writing system used in combination with this, a color CRT, a laser using various exposure wavelengths, a color LC5, or an LED 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 and GSR filters and the wavelength of the uniform exposure light are , is not essential to the present invention; that is, the spectral transmittance distribution of each filter is such that the image exposure light selectively passes through each filter depending on the writing system corresponding to the color information used; Next, it is necessary to be able to selectively form a potential pattern on each filter section by uniform exposure with specific light.

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 divided into units as shown in FIG. 8(b). Even if the size is larger than that of the filter, it will not write on other color filters. In other words, in the example of FIG. Even if writing is performed on the marked B filter section and the area marked with dashed lines is exposed,
No writing is done.

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. 9 and 10, it is possible to prevent the spectral transmittance distributions of the filters shown by solid lines from overlapping each other, or to prevent the spectral distributions of image exposure light shown by broken lines from overlapping each other. is important. 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. I can do it. 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. There is a problem in that it invades the later stage developing device that is housed, causing color mixing. From the above considerations, it is clear that the image forming conditions for recording with a desired density and without image disturbance or color mixture using a -component developer or a two-component developer are as follows: It has become clear that this phenomenon exists in processes that use 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 process, the amplitude of the AC component of the developing bias is changed to ■Ac(
v), when the frequency is set to 11z and the gap between the image bearing member and the developer transporting member that transports the developer is d (m■), 0.2≦VAc/(d−f)≦1 .6.

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 set to V
ac (V), the frequency is f (Ilz), and the gap between the image bearing member and the developer conveying body that conveys the developer is d (m
), it is preferable to satisfy 0.2≦Vac/(d·chi) ((Vac/d) −1500) /f≦1.0.

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 found that there are areas where we can obtain quality images.

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 v) and frequency factor (tlz) 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 conducted using the -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. However, Figures 11 and 12
The results shown in the figure were obtained. Note that the photoreceptor drum 4
1 has a toner image formed in advance. This developing device 1
7 is each developing device 17Y, 17M, 17G shown in FIG.
When the sleeve 7 and/or the magnetic roll 43 rotate, the developer is conveyed on the circumferential surface of the sleeve 7 in the direction of arrow B, and the developer is supplied to the development area E. ing. The developer is a one-component magnetic developer, which is made by kneading and pulverizing 70 wt% of a thermoplastic resin, 10 wt% of a pigment (carbon black), 20-1% of a magnetic material, and a charge control agent to have an average particle size of 15 μm. Furthermore, a fluidizing agent such as silica is added.

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 is conveyed in the direction of arrow B.

The thickness of the developer layer is regulated by a spike control blade 40 made of a magnetic material during transportation. A stirring screw 42 is provided in the developer reservoir 47 to sufficiently stir the developer reservoir, and when the toner in the developer reservoir 47 is consumed, the toner supply roller 39 rotates. , toner T is replenished from the toner hopper 68.

A DC power supply 45 is provided between the sleeve end and the photoreceptor drum 410 to apply a developing bias, and the developer is vibrated in the development area E so that the developer is sufficiently applied to the photoreceptor drum 41. AC power supply 4 so that it is supplied to
6 is provided in series with the DC power supply 45. R is a protective resistance.

FIG. 11 shows the gap d between the photosensitive drum 41 and the sleeve 7.
0.7 m, the developer layer thickness is 0.3 mm, the DC component of the developing bias applied to the sleeve 7 is 50 V, the frequency of the AC component of the developing bias is Iktlz, the maximum of the photoreceptor due to uniform exposure after charging When the potential is set to soo v,
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 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. 11 indicate that the average charge amount of the magnetic toner is -5 μc/g, −3 μc/g, and −2 μ, respectively.
These are the results when using c/g.

For all three curves A, B, and C, the image density is high when the amplitude of the alternating current component of the electric field is 200 V/f1 or more and 1.5 kV/f1 or less, and when it is 1.6 kV/mm or more, the image density is high. It was observed that the toner image that had been previously formed was partially destroyed.

Figure 12 shows that the frequency of the AC component of the developing bias is 2.5.
kHz, 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/m or more and 3.8 kV/fl or less, the image density is high, and when it is 3.2 kV/M or more, the image density is high, and when the amplitude EAC of the alternating current electric field strength is 3.8 kV/fl or more, the image density is large. Some of the Toner statues were destroyed.

As can be seen from the results in Figures 11 and 12, 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, although the average charge amount is a small value, in reality there is a certain proportion of toner with a large charge amount, for example, 20 μc/g or more in size, and it is thought that such toner is mainly used for development. It will be done. 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 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 was investigated, and the results shown in FIG. 13 were obtained.

In FIG. 13, the area marked with ■ is an area where development unevenness is likely to occur due to the low-frequency development bias, the area marked with ■ is an area where the effect of the AC component does not appear, and the area shown with O is an area where development has already been formed. Oo is a region in which the effect of the alternating current component appears, sufficient development density is obtained, and destruction of the already formed toner image does not occur, and [F] 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 the frequency and the 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 region where the AC field strength amplitude EAC is 0.2 to 1 kV/mm for the density curve A in FIG. The alternating current component acts to make it easier for the toner to fly from the sleeve to exceed the darkness value, and even the toner with a small amount of charge is attached to the photoreceptor drum 41.
Development is performed.

Therefore, as the amplitude EAc of the alternating current electric field strength increases, the 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 Fig. 11, the amplitude EAC of the AC electric field strength is 1k).
(area above V) There are several possible reasons. 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 more easily broken. Even if the charged toner adheres to the photoreceptor drum 41, its 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 AC component is too large, the charge on the surface of the photoreceptor drum 41 will leak, resulting in
The phenomenon that the toner becomes difficult to develop also becomes more likely to occur. In reality, it is thought that these factors overlap to saturate or lower the image density.

On the other hand, when the amplitude EAC 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 . 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 tends to be, but this is because toner particles are unable to 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 photoreceptor drum 41. It is caused by

Based on the above experimental results, the inventor of the present invention set the amplitude of the AC component of the developing bias to AC (■), the frequency to (Ilz), and the gap between the photoreceptor drum 41 and the sleeve 7 to d( m), 0.2≦VAC/ (d・
)≦1.6, the toner image already formed on the photoreceptor drum 41 will not be disturbed.
It was concluded that subsequent development could be carried out at an appropriate density. In order to obtain sufficient image density and not disturb the toner image formed up to the previous stage, the image density is in the region of 0.4 in FIGS. 11 and 12 where it shows an increasing tendency with respect to the AC electric field. It is more desirable to satisfy the condition ≦Vac/(d−f)≦1.2. Furthermore, within this region, it is more desirable that the electric field is slightly lower than that at which the image density is saturated, and that the following condition is satisfied: 0.6≦vAc/(d·su)≦1.0.

In addition, in order to prevent uneven development due to the alternating current component, the frequency of the alternating current component is set to 200 tlz or more, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 41, the alternating current 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 500 flz or more.

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. 14 and 15 were obtained. The developer 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 pm and a magnetization of 30 emu.
/ g, resistivity is a carrier created by dispersing fine iron oxide in a resin so as to exhibit physical properties of 10I4Ω-cm, and the resistivity is determined by placing the particles in a container with a cross-sectional area of 0.50cJ. After tapping, place 1 on the packed particles.
A load of kg/cd is applied, and a distance of 10 kg/cd is applied between the load and the bottom electrode.
This value is obtained by reading the current value when applying a voltage that generates an electric field of 00 V/elm. The toner is made of 904% thermoplastic resin and pigment (carbon black).
A small amount of a charge control agent was added to 10% and 4t%, which was then kneaded and pulverized to obtain an average particle size of 10 μm. 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-t % to prepare a developer. In addition,
The toner becomes negatively charged due to friction with the carrier.

FIG. 14 shows the gap d between the photosensitive drum 41 and the sleeve 7.
1. Qmm, the developer layer thickness is 0.71■, the maximum potential of the photoreceptor is soo v, the DC component of the 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 FIG. 4 are the results when toners whose average charge amounts were controlled to be -30 μc/g, −20 μc/g, and −15 μc/g, respectively, were used. A, B,
For all three curves of C, the amplitude of the alternating current component of the electric field is 200
The effect of AC component appears above V/m, and 2500 V
/u+ or more, it was observed that the toner image previously formed on the photoreceptor drum was partially destroyed.

Figure 15 shows that the frequency of the AC component of the developing bias is 2.5.
kHz, and when the alternating current electric field strength EAc is changed under the same conditions as in the experiment shown in Fig. 14, EAc is 500.
When the density exceeds V/as, the image density increases, and although not shown, when it exceeds 4 kV/*■, a part of the toner image previously formed on the photoreceptor drum 41 is destroyed.

As can be seen from the results in Figures 14 and 15, the image density changes to saturate or slightly decrease after a certain amplitude;
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 we conducted an experiment similar to that shown in Figures 14 and 15 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 the frequency elements and obtained the results shown in Figure 16.

In Fig. 16, the area marked with ■ is an area where uneven development is likely to occur due to low-frequency development bias, the area marked with ■ is an area where the effect of the alternating current component does not appear, and the area shown with O is already formed. The area where the toner image is likely to be destroyed, 0, [F] is the area where the effect of the AC component appears and sufficient development density is obtained, and the already formed toner image is not destroyed, and [F] is particularly This is a desirable 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 density curve A in FIG. 14, 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 serves to make it easier for the toner to fly from the sleeve to exceed the darkness value, and even the toner with a small amount of charge is attached to the photoreceptor drum 41 and subjected to development. . 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, in the case of the song wAA in FIG. can be explained. That is,
In this region, as the amplitude of the alternating current electric field strength increases, the toner vibrates strongly, and the clusters formed by toner aggregation are easily broken (as a result, only toner with a large charge selectively adheres to the photoreceptor drum 41). Toner particles with a small charge are difficult to be developed.Furthermore, even if the toner with a small charge adheres to the photoreceptor drum 41, its mirror image force is weak, so it tends to return to the sleeve 7 due to the alternating current bias. If the amplitude of the electric field strength of the component is too large, the electric charge on the surface of the photoreceptor drum 41 leaks, making it difficult to develop the toner.In reality, these factors combine to cause the image density to change. It is thought that it remains constant as the components increase.

Further, the AC field strength is increased, and the amplitude is increased to 2.5. It was found that when the voltage exceeds kV/Tsuru, the toner image previously formed on the photoreceptor drum 41 is 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 cover.

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 14 and 15, 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 vA.

(V) When the frequency is (IIZ>) and the gap between the photosensitive drum 41 and the sleeve 7 is d(m), 0.2≦Vac
/ (d -su) ((VAC/d) -1500) If development is performed under the conditions satisfying /<1.0, subsequent development can be carried out without disturbing the toner image already formed on the photoreceptor drum 41. It was concluded that this can be done at appropriate concentrations. 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≦■Ac/(d-f) ((VAc/d) -1500) It is more preferable to satisfy /s≦1.0. Furthermore, especially among these, 0.5≦V ac/ (d ・'f ) ((VAc/d
) 1500)/≦0.8, a clearer multicolor image without color turbidity can be obtained, and even if the developing device is operated many times, it is possible to prevent toner of a different color from entering the developing device.

In addition, in order to prevent uneven development due to the AC component, the frequency of the AC component is set at 200
11z or more, and when a rotating magnetic roll is used as a means for supplying the developer to the photoreceptor drum 41, the frequency of the AC component is 500Hz or more in order to eliminate the influence of the AC component and the beat caused by the rotation of the magnetic roll. It is even more desirable to do so.

Based on the present invention (the image forming process is as exemplified above, subsequent toner images are sequentially formed on the photoreceptor drum 41 at a constant density without destroying the toner image formed on the photoreceptor drum 41). In order to develop the image, as the development is repeated, ■ use toners with a larger charge amount in order.

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

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

It is more preferable to employ these methods 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, the above-mentioned point (2) is to prevent the toner particles from returning to the sleeve during the subsequent development by using toner particles with a small amount of charge in the initial development. Method (2) is a method in which the toner particles already attached to the photoreceptor drum 41 are prevented from returning 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 AC 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. , above (2) is a method in which the frequency of the AC component is increased sequentially as development is repeated to prevent the toner particles already attached to the photoreceptor drum 41 from returning.
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 sequentially decreasing the alternating current bias as development is repeated. Further, when the above three methods are employed, appropriate image density or color balance can be maintained by adjusting the DC bias respectively.

FIG. 17 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 3a 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 the following properties is laminated.

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

The photoconductive layer 2 is made of a photoconductor such as sulfur, selenium, amorphous silicon or an alloy containing sulfur, selenium, tellurium, arsenic, antimony, etc.; or oxidation of a metal 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, and stilbene derivatives. , charge transporting substances such as styryl derivatives are dispersed in insulating binder resins such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, polycarbonate, acrylic resin, silicone resin, fluororesin, epoxy resin, etc. , a charge generation layer (CGL) and a charge transfer layer (CTL) (Japanese Patent Application No. 60-24)
No. 5178, 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. The colored portion is formed by attaching a filter layer 3a colored by adding a coloring agent such as a dye having a desired color to the photoconductive layer 2 in a predetermined pattern by printing or other means, as shown in FIG. 17 (al). Alternatively, as shown in FIG. 17(b), a coloring agent is applied to a transparent insulating layer 3b uniformly formed in advance on the photoconductive layer 2 in a predetermined pattern by means such as printing, vapor deposition, dyeing, electrodeposition, etc. It can also be formed by attaching a film-like insulating material on which a colored portion has been formed in advance on the photoconductive layer. Can be configured.

Furthermore, the surface of the formed colored portion may be further covered with a transparent insulating layer 3b to form a structure as shown in FIGS. 17(C) and 17(d).

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-
No. 198167, No. 59-201084). For example, as shown in FIG. 18, an insulating layer 3c is provided on one side of the photoconductive layer 2, and a transparent conductive layer 3a consisting of a transparent conductive layer 1-2 and a color separation filter is provided on the other side (the color separation filter is a conductive ) are sequentially deposited and laminated. The transparent conductive layer 1-2 is formed by, for example, depositing ITO.

In the photoconductor with this structure, charging is performed from the insulating N3c side,
Image exposure and uniform exposure are performed from the side 3a consisting of a color separation filter.

The shape and arrangement used for the color separation filter are not particularly limited, but in the case of a linear shape as shown in FIG. perpendicular to the direction of movement shown in (Fig. 19 (1)
ml) and the parallel one (Fig. 19(b)) can both be used. Alternatively, it is preferable to configure it in a mosaic shape as shown in FIGS. 19(C) and 19(d).

A configuration obtained by rotating the configuration shown in FIG. 19(C)(d) by 90 degrees can also be used. These angles are O'' or 90
``A rotated one is preferable, but it is 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 may refer to a photoreceptor having a layer consisting of a monochromatic color filter-free portion (which may be transparent resin, air, etc.); This also includes cases where there are two, four, or more types of filters.

Examples of layers consisting of four types of filters are shown in FIGS. 20(a) to 20(e). Similar to the structure in Figure 19, (a), (b)
) shows each filter arranged in a linear pattern, (C), (d)
, (11) are arranged in a mosaic pattern. In the figure, for example, one that transmits only infrared light may be used. laser(
780 nm), K may be, for example, a transparent filter in addition to the above. In short, it is sufficient to selectively form a potential pattern on each filter portion by uniform exposure, and the color of the filter is not essential. The spectral transmittance distribution of each filter is, for example, the 21st
The ones shown in Figures (a) and (bl) may be used.

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.

Also, to reiterate, in most of the above explanations, green (G), blue (B), and red (R) are used as the spectral characteristics of specific light for uniform exposure and the spectral characteristics of the photoreceptor filter. However, the spectral characteristics are not limited to 61B and R. In short, if the uniform exposure and spectral characteristics of the filter are such that a potential pattern is formed only on a specific filter part (not necessarily constant) on the photoconductor corresponding to the specific light by uniform exposure to specific light, good. Further, when forming a potential pattern on a specific filter, the next uniform exposure may be performed with a broad spectral characteristic including the wavelength of the previous uniform exposure. At this time, the special application
As shown in No. 8171, it is effective to prevent color mixture by completely erasing the charge on the photoconductive layer in the toner-attached area by uniform exposure to specific light and charging after each development, and then performing the next uniform exposure. .

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 22 and 23 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. 22 has a conductive substrate 1
photoconductive parts 2R, 2G having the required spectral sensitivity distribution on the top;
2B, for example, a photoconductive layer 2-2 including a large number of photoconductive parts sensitive to red (R), green (G), and blue (B) is provided, and a transparent insulating layer 3b is provided thereon. There is. The photoreceptor shown in FIG. 23 has a charge transfer layer 2-3a provided on a conductive substrate 1, and portions 2B and 2R1 having different spectral sensitivity distributions on the charge transfer layer 2-3a.
It has a structure in which a charge generation layer 2-3a made of 2G is provided, and a transparent insulating layer 3b is further provided thereon. In the photoreceptor shown in FIG. 23, a charge generation layer 2-3a, a charge transfer layer 2-3,
b constitutes a photoconductive dielectric Jli2-3. Second
Photoconductive layer 2-2 in Figure 2 and charge generation layer 2-3 in Figure 23
The planar structure of a is similar to the insulating layer made of the color separation filter described above, as shown in FIGS. 19(a) to (d) or FIG. 20(
A planar structure similar to that shown in a) to (e) may be used.

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. 24 (al is a perspective view showing the relationship between the laser optical system 39 and the image carrier 41. As shown in FIG. 2, COD
The image formed on the image sensor 36 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 processed by a semiconductor laser which is modulated according to the image data by a command from the CPU. Laser light emitted by the three people 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 is reflected onto the image carrier 41 via the fθ lens 39d and the reflection mirror 39e. Spot exposure. The wavelength of the laser beam is 800 nm, and by selecting the filters as shown in FIG. 4 (al or (b)), the laser beam is transmitted through all the filters.

When performing image exposure by combining a blue image, a green image, and a red image, the semiconductor laser 3 shown in FIG. 24(a)
9a, an optical control system 39f as shown in FIG. The optical modulator is operated by the CPU based on the data, and the above light is focused on the same optical path using a half mirror and guided to the collimator lens 39b.Each wavelength of the laser light is shown in Fig. 4(b). By selecting a filter as shown, only the corresponding filter is transmitted.

In a type of writing system such as a laser, which sequentially scans in the main scanning direction (parallel to the axis of the image carrier 41), the end position of the image carrier at the beginning of writing can be determined easily and accurately. In the sub-scanning direction (circumferential direction of the image carrier 41), rotation of the image carrier 41 may cause a maximum l-scan shift.

Therefore, the filter configuration shown in FIG. 19(b) is stable.

In the filter having the configuration shown in FIG. 19(b), as shown in FIG. 25, an end detection line 41a is provided outside of the endmost filament filter, and the laser beam is detected by the photosensor S1. Then, the timing of writing image data by laser light is synchronized so that each of the linear filters R, G, and B is exposed as a spot. 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. Accuracy can be maintained by varying the scan clock pulse or by adjusting the reflective mirror 398.

When performing imagewise exposure with light in a single wavelength range (e.g. 800nm+), multiple dots can be exposed to one unit of the stripes or mosaic of the filter layer, resulting in a composite of blue, green and red images. When performing imagewise exposure using imagewise exposure light, it is recommended to perform dot exposure with a diameter that necessarily includes one unit of the stripes or mosaic of the filter layer, or that extends over at least two units, to allow for deviations in the writing position. The degree expands from Fig. 19 (a) to Td+, Fig. 20 (a)
It is possible to stably imagewise expose a filter layer having any of the structures shown in (e).

In addition to the above method, in order to perform stable dot exposure, it is preferable to use an image forming method in which each image of the input image is binarized to express gradations in a virtual manner, as described below.

As such methods, for example, the density pattern method shown in FIG. 26 and the dither method shown in FIG. 27 are known. Since the unit matrix includes a plurality of filters of the same color, even if there is a slight positional shift in writing, image reproduction will be performed by the plurality of filters of the same color, which will hinder image reproduction. There is no. When image exposure is performed using image exposure light that is a combination of a blue image, a green image, and a red image, image reproduction becomes more stable if dot exposure is performed with a diameter that necessarily includes at least one unit of the filter.

The density pattern method shown in FIG. 26 is a method of converting one pixel with gradation of an input image into a plurality of pixels with binarization. 1a is a human image, and 2a is the input image 1.
A pixel 5a having a representative density value of the matrix of a is taken out and is a sample for processing, and 3a is a reference density matrix of MXN 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. 27 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 MX for binarizing this sample.
4b is the reference concentration matrix of N, and 4b is the reference concentration matrix of the sample 2b.
is the pattern obtained as a result of binarization 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 linear filter layer having the structure shown in FIG. 19 (al), as shown in FIGS. to 8
A 12×8 matrix (each image data for B, G, and R is a 4×8 matrix) consisting of pixels is used. Second
Figure 8(a) is a matrix for performing image exposure with light in a single wavelength range (e.g. 800 nm), and Figure 28 (bl is a matrix for image exposure using combined image exposure light of a blue image, a green image, and a red image). This is the matrix for when to do so.

In order to ensure that writing is performed on each filter section, the position in the main scanning direction is determined using the same end detection line 41a as described above.
By the detection, 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).

) by detecting laser light with the photosensor S2.

(Ma) For IJ hook writing, a concentrated dither matrix is used for the matrix so that image reproduction will not be affected even if a slight positional shift occurs.
It is preferable to write in the order of spreading from the center of each matrix to the periphery.

In the case of a distributed dither matrix in which dark values are arranged in a dispersed manner, a slight positional shift in dot exposure will write to other filter sections and have a large effect on image reproduction, so a concentrated dither matrix is used. is desirable. The same applies to the density pattern method. blue statue,
When using composite light of a green image and a red image, a dispersed type can also be preferably used.

FIG. 29 shows an example of a case where a plurality of dot exposures are carried out using a matrix as described above using a linear filter layer having the structure shown in FIG. 19(b).

In this example, an 8x6 matrix (image data corresponding to each color is an 8x2 matrix) is used. In this case, a filter detection line is not required. In this case, when image exposure is performed using light in a single wavelength range (for example, 800 nm), a matrix as described above is used in each filter section, and a pulse width variable Uj4 (4 (1F)) is used.

When using a filter layer with a mosaic structure, it is preferable to use a filter layer with no unevenness in the main scanning direction as shown in FIG.
When performing image exposure with light of 0 nm), it is best to perform matrix writing consisting of multiple main scans and sub-scans for one mosaic. When performing exposure, it is preferable to perform matrix writing consisting of a plurality of main scans and sub-scans using a unit spot diameter spanning a plurality of filters of the same color.

The arrangement of the end detection line and filter detection line in this case is illustrated in FIG. 30. 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 lumped dither matrix is used for writing.

When performing image exposure with light in a single wavelength range (for example, Boons), if the writing system is fixed such as CRT, OFT, LC3, or LED, OFT is applied to a filter in advance.

It is necessary to match the dots of LC3 and LED.

In this case as well, in order to reduce the precision in the main scanning and sub-scanning directions, it is desirable that the filter structure and writing pattern shown in FIG. 19(b) have a matrix configuration. In addition, laser, O
The exposure spot diameters of FT, LC3, and LED are preferably matched to the filter shape. For example, Fig. 19 (al, (bl,
In (d), a rectangular shape is preferable.

When image exposure is performed using image exposure light that is a combination of blue, green, and red images, and the writing system passes through multiple filters, it is necessary to align the exposure spot with the color filter portion where color data is to be written. be. In this case, accuracy in the main scanning and sub-scanning directions is required to match the color filter.

Further, it is preferable that the exposure spectra B, G, and R of the writing system are set so that they are transmitted only through the B, G, and R filters on the image carrier, respectively.

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 so that at least one specific color filter is included, or a plurality of exposure spots are included.

Alternatively, spot exposure is performed using a plurality of filters of the same color using a dither matrix or a density pattern matrix. Such positioning can be performed extremely easily. In other words, this means that an image representation unit is performed using a plurality of the same filters.

In addition, we not only perform spot exposure that is larger than the periodic width of the striations or mosaic of the filter by making the periodic width of the filament filter or mosaic filter correspond to the writing density, but also perform writing density that is coarser than the periodic width of the striations or mosaic. It is also possible to perform exposure using

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 used for row planting recording. The size of each filter corresponding to the writing system is 1 as the color repetition width (1 in Figure 19).
It is preferable to set it as 0-500 micrometers. The smaller the filter size, 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. Also, the size of the filter,
If the size is too large, the resolution and color mixing properties of the image will decrease, and the image quality will tend to deteriorate. Therefore, the above l is particularly preferably from 30 to 200 μm. It is preferable that the writing spot diameter is equal to or larger than the period l of the filter. Particularly preferably, it is 1 to 4 times the filter period l. Further, it is preferable that the writing spot diameter of each color is 1.0 to 5 times the reciprocal of the writing density (dat/ms) of each color.

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

The image forming apparatus shown in FIG. 2 above the large blood spot was used. A laser optical system 39 shown in FIG. 24(a) is used as the writing system. However, the image carrier 41 has a long-wavelength sensitized Se photosensitive layer with a thickness of 40 μm on a nickel base, and a 17th photosensitive layer with a thickness of 20 μm.
Blue having the structure shown in Figure (d) and Figure 19+d),
Filter size 1+300 with transparency for green and red
An insulating layer with a thickness of 200 μm was provided, and the circumferential speed was 100 m/sec. While uniformly exposing the image carrier 41 to light using the lamp 4A of the primary charger 4, the image carrier 41 was charged by the DC scorotron corona discharger 4 so that the surface potential of the image carrier 41 was -2000V.

Next, while performing image exposure using digital signals, the image carrier 41 was charged with a secondary charger 5 consisting of a scorotron corona discharger having an alternating current component so that the surface potential of the image carrier 41 was 150 cm. Each filter transmits semiconductor laser light.

Each yellow (Y), magenta (M), and cyan (C) image data is filtered through B, G, and H mosaic filters (see Figure 19).
d), the size of one mosaic is 100μm x tooμm
) in a 4x4 matrix.

Laser writing density is 40 dots/tsuru, writing diameter is 25
μm/dot. Its shape is approximately square. Normally, the writing diameter is set to be approximately twice as large as the writing density, but in this example, it is set to be approximately the same in order to avoid writing to other filter sections.

The writing timing is such that a specific filter is detected by the filter detection line, the detection of the edge detection line by the laser beam is used as a signal, and each image data is made to correspond to the filter every 4 pixels in the main scanning direction. I switched to M and C and wrote. (See FIG. 30) Next, by performing uniform exposure through a blue filter, an electrostatic image having a potential of -50 to 300V was formed. 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 contained in the resin at 50 wt%.
Contains dispersed particles, average particle size is 30μmS magnetization is 30ea+
u/g, with a carrier having a resistivity of 1014Ω or more;
It is used under conditions where the toner ratio in the developer is 20-t%, which is composed of a non-magnetic toner with an average particle size of 10 μm, which is made by adding 10 parts by weight of a benzidine derivative as a yellow pigment to a styrene-acrylic resin and other charge control agents. there was. Further, the outer diameter of the developing sleeve 7 is 30n, and its rotation speed is 1100 rpm.
, the magnetic flux density of the N and S magnetic poles of the magnet body 43 is 900 Gauss,
The rotation speed is 11,000 rpm, the thickness of the developer layer in the developing area is 0.7 m, and the gap between the developing sleeve 7 and the image carrier 41 is 1.
, 0, and a non-contact development condition in which a DC voltage of 1100V and a superimposed voltage of AC voltage of 2000V (the amplitude of the process wave is ci x 2000V) was applied to the developing sleeve 7. Ta.

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 separating the developing sleeve from the electric charge and leaving it in a floating state, or by grounding it, or by actively applying a DC bias voltage of the same polarity as the electrostatic image (i.e., the opposite polarity to the toner charging) to the developing sleeve. Among these, it is preferable to apply a DC bias voltage.

Further, the driving of the developing device was stopped during non-developing time.

Since the developing devices 17M and 17C are also designed to perform development under the same non-contact developing conditions as the developing device 17Y, the developer layer on the developing sleeve does not need to be removed.

The developing device 17M uses a developer in which the toner in the developing device 17Y is changed to a toner containing polytungstophosphoric acid as a magenta pigment instead of a yellow pigment, and the developing device 17C uses the same 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 also be used, and
The order of the colors to be developed can also be determined appropriately so that a clear color image can be obtained. In particular, the order of developing colors may be related to the sharpness of the color image and the potential contrast that can be obtained, and therefore needs to be carefully determined.

The surface of the image carrier 41 developed by the developer 17Y was recharged to a surface potential of 120 V by a scorotron corona charger, and then uniformly exposed to light through a green filter. The position of the electrostatic image obtained by this is background part -20
It was -300V with respect to V. This electrostatic image was transferred to a developing sleeve with a DC component of -5OV and an AC component of 2.5 kll.
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 surface potential increases by +10■ by the Scorotron charger.
After being recharged to , uniform exposure was performed through a left filter. As a result, +250 for the background +IOV
Form an electrostatic image of V, and transfer this electrostatic image to a developing sleeve with a DC component of -50V and an AC component of 2.5kHz, 2000V.
Developing was carried out in the developing device 17C under the same conditions as in the developing device 17Y, except that a voltage of 1 was applied.

When this third development is performed and a three-color image is formed on the image carrier 41, the corona discharger 21 and the pre-transfer lamp 22 are activated, thereby transferring the color image. The image was transferred onto copy paper 8 using a transfer device 9, separated using a separator 10, and fixed using a heat roller 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.

Isamu Ouse 1 The image forming apparatus shown in FIG. 2 was used. For the writing system, an optical control system 39f shown in FIG. 24(b) is used in place of the laser optical system 39 and semiconductor laser 39a shown in FIG. 3ee with a thickness of 60 μm.T e l.

Furthermore, a 2 μm thick layer of Se, Te, etc. is added to the surface layer. 17(d) with a thickness of 20 μm on the Se photosensitive layer sensitized to long wavelength by
The size of one filter having the structure shown in FIG. 19(d) and having transparency in blue, green, and red is 33um x 50.
μm (j2+ = 100 μm, 1g = 100
It has an insulating layer with a diameter of 100 μm
am/sec. While uniformly exposing the image carrier 41 to light using the lamp 4A of the primary charger 4, the image carrier 41 was charged by the DC scorotron corona discharger 4 so that the surface potential of the image carrier 41 was -2000V.

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

Each yellow (Y), magenta (M), and cyan (C) image data is filtered through B, G, and H mosaic filters (see Figure 19).
d), the size of one mosaic is 100 μmxloo
μm) and the pixel size is 100 μm x 100 μm.
Writing was performed using a ×4 dither matrix (unit matrix size is 400 μm×400 μm).

Laser writing density is 10 dots/Tsuru, writing diameter is 20
It is 0 μm/dot. Its shape is approximately square.

In this example, the writing diameter is 1.0 to 5 of the reciprocal of the writing density.
The size is set to about double the size, but this setting is made so that writing is performed to the same adjacent filter section.

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. Y, M, and C were written independently in correspondence with each other (see Figure 30).

In this example, since the writing diameter is larger than the filter period, there is an advantage that information can always be written to a specific filter without complete synchronization with the filter position. Further, the dither matrix can be a centralized type, a distributed type, or a variation thereof. Of course,
Intensity modulation or a combination of intensity modulation and dither matrix can also be preferably used. Further, a density pattern method can also be preferably used.

Next, by uniform exposure through a blue filter, an electrostatic image having a contrast of 350 cm in absolute value was formed. 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 70-t% in the resin.
Contains dispersed particles, average particle size is 30μm, magnetization is 30Cmu
/g, a carrier with a resistivity of 101 ΩG or more; and a positively charged nonmagnetic toner with an average particle size of 10 μm, which is prepared by adding 10 parts by weight of a benzidine derivative as a yellow pigment and other charge control agents to a styrene-acrylic resin. It was used under the condition that the toner ratio in the toner was 20-t%. The outer diameter of the developing sleeve 7 is 30 mm, and the rotation speed is 1100 mm.
rp, the magnetic flux density of the N and S magnetic poles of the T11 stone body 43 is 90
0 gauss, the rotation speed is 11000 rpm, the thickness of the developer layer in the developing area is 0.7 gauss, the gap between the developing sleeve 7 and the image carrier 41 is 1.0 gauss, and the developing sleeve 7 is equipped with a +200 cm DC electric type. and 2.5k) Iz, 2000■ AC voltage superimposed voltage (the amplitude of the construction wave is rx2oo.

(2)) 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.

Further, the driving of the developing device was stopped during non-developing time.

Since the developing devices 17M and 17C are also designed to perform development under the same non-contact developing conditions as the developing device 17Y, the developer layer on the developing sleeve does not need to be removed.

This developing device 17M uses a developer in which the toner in the developing device 17Y is changed to a toner containing polytungstophosphoric acid as a magenta pigment instead of a yellow pigment, and the developing device 17C uses the same ( A developer was used in which the toner was changed to a toner containing a copper phthalocyanine derivative as a cyan pigment.Of course, color toners containing other pigments or dyes can also be used.
The order of the colors to be developed can also be determined appropriately so that a clear color image can be obtained. In particular, the order of colors to be developed needs to be carefully determined because it may be related to the sharpness of the color image and the potential contrast during uniform exposure.

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, uniform exposure was performed through a green filter. The position of the electrostatic image obtained by this is the background area +
It was -50v compared to 350V. This electrostatic image
DC component +250■, AC component 2.5 on the developing sleeve
Development was carried out in the developing device 17M under the same conditions as in the developing device 17Y, except that a voltage of 2000 V was applied.

Similarly, the scorotron charger increases the surface potential to +400
After being recharged to V, uniform exposure was performed through a red filter. As a result, for the background part +400 V, +
A 150 V electrostatic image is formed, and this electrostatic image is applied to the developing sleeve with a DC component of +300 V and an AC component of 2.5 kll.
z, developing device 17Y except that a voltage of 2000 V was applied.
The film was developed using the developing device 17C under the same conditions as in .

When this third development is performed and a three-color image is formed on the image carrier 41, the corona discharger 21 and the pre-transfer lamp 22 are activated, thereby transferring the color image. The image was transferred onto copy paper 8 using a transfer device 9, separated using a separator 10, and fixed using a heat roller 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.

As in Example 1, the color image recorded in the above manner has not only areas where the color toners are loosely adhered to each other but also areas where the toners are closely adhered to each other. It was extremely clear.

As described above, not only the developing method described in Example 1.2, but also a modified example of the developing method performed without rubbing the photoreceptor, in which only the toner is taken out from the composite developer onto the developer transport carrier,
A method of performing one-component development using toner in an alternating electric field (Japanese Patent Application Laid-Open No. 59-42565, Japanese Patent Application No. 58-231434)
, a method of developing with a monocomponent developer in an alternating electric field by providing a linear or net-like control electrode (Japanese Patent Laid-Open No. 56-1257)
No. 53), a method of providing a similar control electrode and performing development with a two-component developer in an alternating electric field (Japanese Patent Application No. 58-97973)
Needless to say, method No. 1) is also included in the multicolor image forming method according to the present invention.

In the above embodiments, corona transfer is used as the toner image transfer method, but other methods may also be used. For example, Japanese Patent Publication No. 46-41679, No. 48-
When the adhesive transfer method described in Japanese Patent No. 22763 is used, transfer can be performed without considering the scratchability 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 and applying primary and secondary charging from the insulating layer side, image exposure and uniform exposure from the filter side (Japanese Patent Application No. 199547/1983). .

In addition to the image forming method described above, a process in which charging and image exposure are performed separately can be used. This process forms charges on the photoconductive layer by performing primary charging followed by secondary charging of substantially opposite polarity. This process is the same as the case without image exposure in Figure 1 (1) and (2). ), then image exposure is performed, and the resulting potential contrast is smoothed by tertiary charging. (This state is shown again in Figure 1 [2]
It is in a state of ) Next, the process of uniform exposure and development of specific light is repeated in the same manner as shown in FIG.

In addition, as shown in Japanese Patent Application No. 59-187045, -order charging and simultaneous image exposure, followed by secondary charging of substantially opposite polarity, and then uniform exposure to specific light. Repeat the development process. It is also possible to use an image forming method in which the processes of secondary charging, imagewise exposure, subsequent secondary charging of substantially opposite polarity, and uniform exposure to specific light and development are repeated. In addition, all of the above explanations have been made regarding examples of color printers that use so-called three-color separated image data and three primary color toners, but embodiments of the present invention are not limited to this, and various types of multi-color image recording It can be widely used in devices, color electrophotographic printers, etc.

This example uses a color LC3 for image exposure. The structure of this LC5 uses a white fluorescent light source. & Crystal Lashata Panel Corresponding to each segment, BSG provided in a straight line or staggered pattern.

It has an R filter. The filters on the image carrier each have a B value for the image exposure through the liquid crystal shutter.
, G, and R filter sections were used.

The focusing rod 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.

By doing so, when a filter layer as shown in FIGS. 19(a) and 19(b) is used, the permissible range of setting accuracy of the liquid crystal shutter is widened. This is particularly advantageous since it can be separated from the charging wire.

Of course, the same applies to filter shapes as shown in FIGS. 19(C) and 19(d).

Furthermore, it is also possible to synchronize and switch the lighting of the fluorescent lamps corresponding to each image data writing using three-color fluorescent lamp light sources. In this case, it is not necessary to provide a filter in each segment of the liquid crystal shutter panel.

Alternatively, a plurality of writing systems may be provided to simultaneously write to each filter section.

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

FIG. 31 is an enlarged sectional view of a main part of LC339-2, and FIG. 32 is a schematic perspective view showing the positional relationship between LC339-2 and image carrier 41. In FIG. 32, the casing 39-2f is indicated by a broken line so that the inside of the LCS 39-2 can be seen. In the figure, 39-2a is a fluorescent light source, 39-2b is a liquid crystal shutter panel, 39-2C is a liquid crystal shutter segment, 39-2d is a focusing rod lens array, 39-28
is a driving rc that drives each liquid crystal shutter segment 39-2C. Writing is performed on the image carrier 41 from the back side of the charger 5.

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

The image carrier 41 has a long wavelength sensitized 5e-
A filter size that has a structure shown in FIGS. 17(a) and 19(a) with a thickness of 30 μm on a Te photosensitive layer and has translucency in blue, green, and red! A 150 μm insulating layer was provided, and the circumferential speed was 50 m/sec. While uniformly exposing the image carrier 41 to light using the lamp 4A of the primary charger 4, the image carrier 41 was charged by the DC scorotron corona discharger 4 so that the surface potential of the image carrier 41 was -2000V.

Next, while performing image exposure using digital signals, the image carrier 41 was charged with a secondary charger 5 consisting of a scorotron corona discharger having an alternating current component so that the surface potential of the image carrier 41 was 150 cm. Each filter transmits specific light.

Each Y, M, and C image data was written as one dot for one filter line in the sub-scanning direction.

Writing density is 20 dots/mm, writing width is 50
μm/dot. Writing spot diameter is 100 μm
, which is twice the width of one filter.

As for the writing timing, a specific filter was detected by a filter detection line, and each image data was written in a 2×2 distributed dither matrix in correspondence with the color of the filter.

FIG. 33 schematically shows a state in which writing is performed on the G filter section, and a circular broken line indicates the exposure range of one spot.

Thereafter, in the same manner as in Example 1, a color image was formed by repeating uniform exposure with specific light, development, and recharging. The obtained color image is the same as that of Example 1.2.
It was of good quality, as was the case at the store.

In this example, as in Example 3, color LC3 was used for image exposure.
This is an example using . The structure of this LC3 uses three white or B, G, and R fluorescent light sources, and has B, G, and R filters arranged in a straight line or in a staggered manner, corresponding to each segment of the liquid crystal shutter panel. It is.

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.

As described above, the focusing rod 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.

Alternatively, the size of the shutter element is made approximately equal to or larger than the reciprocal of the filter period. That is, the exposure diameter of the unit segment onto the image carrier is made approximately equal to or larger than the reciprocal of the filter period.

By doing so, when a filter layer as shown in FIGS. 19(a) and 19(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 FIGS. 19(C) and 19(d).

Furthermore, it is also possible to synchronize and switch the lighting of each fluorescent lamp corresponding to each image data writing using fluorescent lamp light sources of three different colors, for example, B, G, and R. In this case, it is not necessary to provide a filter in each segment of the liquid crystal shutter panel.

Alternatively, a plurality of writing systems may be provided to simultaneously write to each filter section.

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

FIG. 31 is an enlarged sectional view of a main part of LC339-2, and FIG. 32 is a schematic perspective view showing the positional relationship between LC339-2 and image carrier 41. In FIG. 32, the casing 39-2f is indicated by a broken line so that the inside of the LC339-2 can be seen. In the figure, 39-23 is a fluorescent light source, 39-2b is a liquid crystal shutter panel, 39-2c is a liquid crystal shutter segment, 39-2d is a focusing rod lens array, 39-2
e is a driving IC that drives each liquid crystal shutter segment 39-2C. Writing is performed on the image carrier 41 from the back side of the charger 5.

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

The image carrier 41 is made of As, S and 40 μm thick on a Ni substrate.
e. On the photosensitive layer, one filter having a thickness of 15 μm and having the structure shown in FIG. 17(a) and FIG. 19(d) and having transparency in blue, green, and red is placed. 30x30μm filter period lI = 90ttm, with an insulating layer of lt -60μm, and its circumferential speed is 50m5/se.
c. This image carrier 41 was charged by a DC scorotron corona discharger of the primary charger 4 so that the surface potential of the image carrier 41 was -2000V.

Next, while performing image exposure using digital signals, the image carrier 41 was charged with a secondary charger 5 consisting of a scorotron corona discharger having an alternating current component so that the surface potential of the image carrier 41 was +300. Each filter transmits specific light.

Each Y, M, and C image data was written independently.

Each writing density is 1O dot/fin, writing width is 100μm
/dot. The writing spot diameter is 150 μm, which is two to three times the width of one filter period.

As for the write 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. 34 schematically shows a state in which writing is performed using green light, and a circular broken line indicates the exposure range of one spot. One spot diameter extends over a plurality of filters of the same color.

Thereafter, in the same manner as in Example 1, a color image was formed by repeating uniform exposure with specific light, development, and recharging. The obtained color images are the same as those of Examples 1 to 3 above.
It was of good quality, as was the case at the store.

In Example 3.4, as the writing system, in addition to the above-mentioned laser and LC3, devices that have the same function as the LC3, such as LISA using magnetic polarization, color CRT, and OFT, are used. When using color FT, a filter can be installed on the fiber plate, or
By providing phosphors with different wavelength ranges, it is possible to obtain light having different wavelengths with different spectral characteristics.

Oketsu Tanko The above Examples 1 to 4 are all examples in which image exposure is performed using one light scanning optical system, but a color separation filter or the like is provided corresponding to each part of the color component to be color separated. It is also possible to perform image exposure by operating two image exposure devices at the same time.

Figure 35 (al is from flat tube to R, B, G monochrome CRT, R
-CRTSB-CRT, the color images displayed by G-CRT are synthesized by a half mirror system HM, and the lens l,
Image exposure is performed by forming an image on the image carrier 41 using the light e. This corresponds to the application of a Kinereco device, and includes the laser optical system 39, semiconductor laser 39a, and optical control shown in FIGS. It is basically the same as the device using system 39f.

In Figure 35(b), the three-color portion is the flat color CRT of the mold.
Image exposure is performed by forming a displayed color image onto a photoreceptor using a lens. Image exposure performs intensity modulation, assigns 16 bits to 1 dot, and
56 gradation recording was performed.

The image forming method is the same as in the second embodiment.

The image forming apparatus shown in FIG. 36 differs from the process shown in FIG. 2 in which image exposure is performed almost simultaneously with charging, in that charging is performed by a charger 4', reverse polarity charging is performed by a charger 5', and then image exposure device Lm is used. , LG, and LR, and then charging for potential smoothing by the charger 5'', and then the second
As shown in the figure, image formation is performed by repeating uniform exposure to specific light, development, and charging for potential smoothing. The rest of the equipment configuration is the same as in the garden. In this image forming method, each image exposure device 39-B, 39-G,
39-R can be arranged in parallel.

(Of course, the configuration described in FIG. 2 or Examples 1 to 5 can also be used.) The deviation of each image exposure position is
This is compensated for by shifting the writing timing of image data.

As already explained, the image exposure device includes a laser optical system, CRT, 0FTSLC3, and LED.

A device that emits monochromatic light such as LISA may be used.

Blood Removal ±1 The image forming apparatus shown in FIG. 37 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, uniform exposure is performed using a lamp 6 equipped with blue, red, and green lights, and the surface potential of the image carrier 41 after development is made uniform using the charger 5 of the image exposure device. 2
This is different from the multicolor image forming apparatus shown in the figure.

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, when forming a three-color image, for example, the image carrier 41 is charged by the charger 4, the charger 5 performs image exposure and makes the surface potential uniform, and then a lamp is placed on the surface of the image carrier 41. A developing device 17Y develops the potential pattern formed thereby to form a yellow toner image. This toner image is transferred to the developing device 17M, 1
7G, 17K, pre-transfer lamp 22, transfer device 9, separator 1
0, it passes without being affected by the cleaning device 12 and charger 4. When the image carrier 41 on which the toner image has been formed reaches the position of the charger 5, it undergoes corona discharge and its surface potential becomes uniform, and it is uniformly exposed to green light obtained from the lamp 6, forming a potential pattern. be done. Subsequently, this is developed by the developing device 17M to form a magenta toner image. Similarly, a potential pattern is formed using red light and a developing device? ! 217C development is performed to obtain a three-color toner image.

When forming a monochromatic image, the blue, green, and red lights of the lamps 6 are simultaneously turned on to the charged and image-exposed image carrier 41 to form a potential pattern on the surface of the image carrier 41, which is then developed. Attire? By developing one or a combination of 517C to 517C to 17, a monochromatic image with sufficient image density and high resolution can be obtained. (Can be done with white light.)
.

This multicolor image forming apparatus has an hour wheel 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. 37 and FIG. 2 indicate the same functional members.

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, the process of photoelectrically converting color-separated light obtained by optically scanning an original to obtain an image signal, and forming a base image on the image signal is repeated to form a toner image of each color on the image forming body. In a color image forming apparatus that forms images in a superimposed manner, images are preferably formed by a color image forming apparatus having a control means for synchronizing the initial writing on the image forming body and the optical scanning of the original document.

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

In FIG. 2, FIG. 36, and FIG. 37, 32 is a document holding plate that brings the document 31 into close contact with the document table, and 34 is the document 31
Light L when scanning exposure is performed 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 mirror group 34 are moved for scanning. The light focused by the lens 35 casts a reduced image onto the surface of a CCD image sensor 36 having color filter layers 52 of B, G, and R shown in FIG. The light L1 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. φ1, φ2 in speed
The transfer section (CCD shift register) 55 is main-scanned in the direction of the arrow X by the two-phase drive pulse 53 of the output 5.
6. The output signal obtained here is input to the image data processing section 37 shown in FIGS. 2 and 36, where color correction and image processing are performed. This is stored in the image memory 38 as required.

Based on the image data obtained in this manner, modulation of the laser beam is performed.

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.

Note that 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-? 'CRTJPOFT, LISA and LC
3 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, LC3s, LISAs, OFTs, etc. are disposed in a planar manner in correspondence with the parts of each component to be color separated, such as a color separation filter, facing the image carrier. A control means for driving and controlling this element group selectively operates the element group based on image data, and simultaneously exposes a flat portion of a stationary image carrier to light without scanning the image carrier. An electrostatic latent image can be formed on a flat surface.

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

The output signal from the COD image sensor 36 is processed by the image forming system shown in FIG. 39, and image formation is performed.

In FIG. 39, the recording device, dot pattern memory, and image forming process are controlled and driven by control signals from the central processing unit (CPU), such as the exposure system in FIG. 2, FIG. 36, or FIG. 37. (lamp 33, mirror 34, lens 35), the CCD image sensor 36, which is a type of color scanner,
, H and outputs an analog video signal.

This signal is subjected to shading correction in order to remove distortion caused by the A/D conversion conversion color erasing information optical system, etc., and is temporarily input to the buffer memory to make each B, G, and R correspond to the same image position. Then, B from the buffer memory
SG and R signals are Y and M.

Complementary color conversion is performed to C, and gradation correction is performed. The filter used for the photoreceptor is B as shown in FIG.

If it is composed of three types of filters, G and R, Y,
The image data is separated into M and C image data.

On the other hand, when it is composed of four types of filters for B, G, and R, the black component is extracted from each data of Y, M, and C (UCR).
) to separate chromatic color components and achromatic color components. Here, the chromatic color components Y, M, and C are color-corrected and tone-corrected together with the black component (BK).

Next, it is input to a pattern generator (PG). Here, for example, after being changed into a digital dot pattern signal based on a 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 a page memory, but instead is stored in a line memory required as a buffer. The image is outputted to the recording device via the image forming apparatus, 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, FIG. 36, or FIG. 37, which has already been explained, is used. In addition, as an image carrier, it detects the potential of the photoreceptor, detects the environment of the drum (temperature, humidity, fatigue), and forms a reference image. 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 written on 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.

As described in detail in Section 8, the image forming method according to the present invention uses an image carrier having a surface insulating layer and a color separation function within the plane, and each image data is divided into each color separation function. An electrostatic latent image is formed corresponding to the area, and then a potential pattern is formed for each of the color separation function areas by uniform exposure with specific light, and then developed. Therefore, the image exposure system can be made compact, the image memory can be saved, and it can be advantageously adapted to image data transfer and storage systems based on point sequential or line sequential systems. In addition, there is no need to align various images unlike in the conventional electrophotographic color system having a transfer drum, and the apparatus can be made smaller, faster, and more reliable. Moreover, the resulting image is
There is no color shift at all, and the result is high quality with excellent reproducibility.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and FIG. 1 [1], [2], [3], [4], [5], [6]
], (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 (a), Mt. , Fig. 5, Fig. 6, Fig. 7 and Fig. 2
Figure 1 (al, (bl) is a graph showing the spectral transmittance of the filter, Figure 8 (a), (bl is a schematic plan view showing an example of an exposure spot for a mosaic filter, Figures 9 and 10 are graphs showing the spectral transmittance of the filter. Graphs showing the spectral transmittance and spectral distribution of exposure light, Figures 11 and 12 are graphs of data obtained when using a one-component developer, and Figure 13 is a graph of data obtained when using a one-component developer. Graphs showing the relationship between the amplitude and frequency of the AC bias in the case of FIGS. 14 and 15
The figure is a graph of data obtained when a two-component developer is used, Figure 16 is a graph showing the relationship between the amplitude and frequency of AC bias when a two-component developer is used, and Figure 17 (al,
(b), (C1, [dl is a cross-sectional view of each photoreceptor, FIG. 18, FIG. 22, and FIG. 23 are cross-sectional views of other photoreceptors, FIG. 19 (al, (b), (C) , (d+ and Figure 20 (in), (bl, (C), +dl, (e) are plan views showing the arrangement of filters on the surface of the photoreceptor, Figure 24 (a) is the laser optical system and image carrier 24(b) is a schematic diagram of the optical control system of the laser optical system, FIGS. 25, 28 (al, (bl, 29, 30)
33 and 34 are plan views showing the method of determining the position of the exposure spot in image exposure, FIG. 26 is a diagram showing the step of disulfidizing the input image by the density pattern method, and FIG. FIG. 31 is an enlarged schematic sectional view of the liquid crystal shutter; FIG. 32 is a schematic perspective view showing the positional relationship between the liquid crystal shutter and the image carrier; FIG. 35 (a) and (b) are schematic perspective views showing the relationship between an optical system using a CRT and an image carrier, FIG. 36 is an internal schematic diagram of an image forming apparatus using another image forming method, and FIG. 37 38 is an enlarged schematic diagram showing the structure of a CCD image sensor, and FIG. 39 is a block diagram showing the image forming system. In addition, in the reference numerals shown in the drawings, 1... Conductive substrate 2... Photoconductive layer 3... Insulating layer. 3a...Filter layer 4.5...Charger 6.6B, 6G, 6R...Uniform exposure device 17Y, 17M, 17C, 17K...Developer 36...COD image Sensor 37... Image data processing section 38... Image memory 39... Laser optical system 39-2... Liquid crystal shutter 41... Photosensitive drum (image carrier) R... Red filter G...Green filter B...Blue filter F,...Blue filter FG...Green filter F,...Red filter L, l...Red light,... ... Blue light, ... Green light TY, ... Yellow toner TM, ... Magenta toner D, ... Developer T, ... Toner. Agent Patent Attorney Hiroshi Aisaka Figure 2 Figure 5 Figure 6 Saka, Cho Tnm+ Fu 7 In 400 500 600 700
Bo. Week length +nm) Fig. 11 Fig. 12 EACIKv/mmJ (bin (…Y) t-, 1-: Book building (old leaf) 11 shoes fil
V, li is W! Jf,)
d＞4-! ! :! /'!
/+1il-ikfi') 13th country, Figure 14 EAC (Kv/rnm) Tan1tsui';'1 Figure 16 Oi 2fCK,,] Figure 19 (a) (C) Figure (b) Figure 20 Happy Figure 21 (a) (b) Liquid length (n
m) Wavelength (nml Actual Figure 22, Figure 23, Figure 24, Figure 25, Figure 26 (b), Figure 32, Figure 33; Figure 34, Figure 36, Procedural Manual) 1. Indication of the case 1986 Patent Office No. 74536 2 Name of the invention Image forming method and its device 3 Person making the amendment Relationship to the case Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name name
(127) Roku Konishi Photo Industry Co., Ltd. 4, Agent address: FINE Building 6, 2-4-11 Shibasaki-cho, Tachikawa-shi, Tokyo, Number of haimei increased due to the amendment 7, Details of the invention in the specification subject to the amendment Explanation column and Figure 37 (1) of the drawings
), "blade" on page 23, line 6 of the specification is replaced with "device".
I will correct it. (2), r2-3aj on page 56, line 2, r2-3
Correct it to b and J. (3) "Break 1" on page 83, line 9 and page 87, line 5 will be corrected to "double-dot chain." (4) "Device" in the first line of page 91 is corrected to "light." (5) On page 94, line 18, "Figure 2 and" is corrected to "Figure 2,". (6) Figure 37 of the drawing is corrected as shown in the attached sheet. -That's all-

Claims (1)

[Claims] 1. An electrostatic latent image is formed by selectively exposing each color separation function portion of an image carrier having a surface insulating layer and having a color separation function within the plane. forming a potential pattern for each of the color separation functional parts by uniformly exposing the image carrier to specific light;
An image forming method comprising the step of performing development. 2. The image forming method according to claim 1, wherein the selective exposure is performed using light that passes through each color separation functional portion. 3. The image forming method according to claim 1, wherein the selective exposure is performed using light in a wavelength range corresponding to each color separation functional portion. 4. The image forming method according to any one of claims 1 to 3, wherein the selective exposure is performed by scanning exposure. 5. The image forming method according to any one of claims 1 to 3, wherein the selective exposure is performed by simultaneous exposure. 6. Exposure means that faces an image carrier having a surface insulating layer and has a color separation function in the plane and selectively exposes a predetermined color separation function portion of the image carrier; a specific light; An image forming apparatus comprising: a uniform exposure means according to the invention; and a developing means, the image forming apparatus having a control means for controlling the exposure means that selectively performs exposure based on image data. 7. The image forming apparatus according to claim 6, wherein the exposure means that selectively performs the exposure is an exposure means that performs the exposure using light that passes through each color separation functional portion. 8. The image forming apparatus according to claim 6, wherein the exposing means for selectively exposing to light is an exposing means for exposing with light in a wavelength range corresponding to each color separation functional portion. 9. The image forming apparatus according to any one of claims 6 to 8, wherein the exposure means that selectively performs exposure is a scanning exposure means. 10. The image forming apparatus according to any one of claims 6 to 8, wherein the exposure means that selectively performs exposure is a simultaneous exposure means.