JPS62124565A - Color image forming method - Google Patents

Abstract

PURPOSE:To easily control the gradation characteristic of a formed image by relatively changing the image exposing and electric discharge of a primary latent image forming stage. CONSTITUTION:An insulating layer 3 of a photosensitive body 4 is formed by sticking insulating materials such as resins respectively colored by the coloring agents added thereto to a prescribed pattern on a photoconductive layer 2 by a means such as printing. The photosensitive body 4 rotates in an arrow direction and an electrostatic charger 5 uniformly charges the surface of the body 4 by positive corona discharge in the stage of forming the color image with a copying machine. Uniform irradiation of white light may be used in combination if the injection of electric charge to the body 4 in said electrostatic charge is difficult. Image exposing light I is made incident on the charged surface of the body 4 by a image exposing device 6. A discharger 61 makes the corona discharge of AC or DC of the code opposite from the charger 5 at the same instant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image forming method, and more particularly to a color image forming method using a photoreceptor having a color separation function member and having an insulating layer on the surface. .

[Background of the invention]

Regarding the above-mentioned color image forming method, a photoreceptor having a distribution layer of a color separation filter as a color separation function member is subjected to a uniform charging step by discharge and a primary latent image formation step by image exposure and discharge, and then a specific light is applied to the photoreceptor. The present inventors previously invented a method for synthesizing a color image on a photoreceptor without color shift by repeating an electrostatic image formation process using uniform exposure and a development process using corresponding colored toners (patent application). Showa 59-185440
No. 187044). Since such a color image forming method forms a color-separated latent image in one image exposure, it is complicated to control the gradation of the formed image.

For example, using a photoreceptor that has a transparent insulating layer on its surface but no color separation function member, the surface of the photoreceptor is uniformly charged, the charged surface is exposed to a color separation image and the charge is removed, and then A method for synthesizing a color image on a transfer material by repeating the steps of performing uniform exposure, developing the electrostatic image formed thereby with a corresponding color toner, and transferring the obtained toner image to a transfer material. In this method, the gradation is controlled by changing the light image exposure position for each color separation image (Japanese Patent Laid-Open No. 50-753).
Publication No. 6). In addition, in a method of reproducing a monochromatic image by performing the same process only once using a similar photoreceptor, image exposure and charge removal are performed in two or three stages with the exposure level gradually lowered. Either it is carried out under discharge-dominant conditions that lower the surface potential, or vice versa, it is carried out under discharge conditions that gradually increase the exposure level and raise the photoreceptor surface potential.
It is known to increase the gradation (Unexamined Japanese Patent Publication No. 59-3
No. 9740 and No. 39741), and it is introduced that this method can also be applied to color copying machines that combine color images on a transfer material (Journal of the Electrophotographic Society Vol. 22, No. 1).
. When this method is used to form a color image on a photoreceptor having a color separation function member as described above, a potential pattern is likely to be generated on the surface of the photoreceptor during the primary latent image forming process, and the potential pattern is similar to that of a specific light. When superimposed on an electrostatic image created by uniform exposure, color stains and color deviations tend to occur in color images.

[Purpose of the invention]

The present invention provides for easily controlling the gradation of a formed image in a color image forming method in which a color-separated latent image is formed in one image exposure using a photoreceptor having a color-separating function member as described above. The present invention provides a method.

[Structure of the invention]

The present invention also provides a method using a photoreceptor having a color separation function member that forms a color separation latent image in one image exposure.
For example, it was discovered that it was possible to control the gradation of a color image without color shift by changing the image exposure position, and it was made based on this knowledge. After a photoreceptor consisting of layers is subjected to a uniform charging process using electric discharge, a primary latent image forming process using image exposure and electric discharge, an electrostatic image forming process using uniform exposure to specific light, and a developing process using color toner. A method for forming a color image by repeating the steps, characterized in that the gradation, etc. of the formed image is controlled by relatively changing the image exposure and discharge in the primary latent image forming step. In a color image forming method.

〔Example〕

Hereinafter, the present invention will be explained with reference to illustrated examples.

1 to 4 are schematic partial sectional views showing examples of the layer structure of the photoreceptor used in the present invention, and FIGS. 5 to 7, respectively.
Figures 8 and 9 are partial plan views showing examples of the distribution shape of color separation filters in the filter layer of the photoreceptor, respectively.
The figures are a schematic configuration diagram showing an example of a copying machine implementing the present invention, FIG. 10 is a process diagram showing the principle of color image formation,
Figures 11, 12, 14115, 17, 19, 13, 16, 18, and 20 respectively show relative image exposure and discharge in the primary latent image forming step. 2 is a schematic diagram of an image exposure portion showing examples of changing methods, and a graph showing a relationship between the exposure amount and electrostatic image potential obtained by those methods.

In FIGS. 1 to 4, 1 is a conductive member formed into an appropriate shape structure as required, such as a cylindrical shape or an endless belt shape, and 2 is a photoconductive layer made of an inorganic photoconductor or an organic photoconductor. ,
3 is an insulating layer including a layer 3a consisting of a distribution of minute color separation filters of red (8), green (G), blue (B), etc. formed from various polymers, resins, etc. and colorants such as dyes. be. The insulating layer 3 of the photoreceptor 4 in FIG. 1 is formed by attaching an insulating material such as a resin colored with a coloring agent onto the photoconductive layer 2 in a predetermined pattern by means such as printing. The insulating layer 3 of the photoreceptor 4 in FIG. 2 is the same as the insulating layer 3 in FIG.
The insulating layer 3 of the photoreceptor 4 in FIG. 3 has a transparent insulating layer under it, and the photoreceptor 4 in FIG. Insulating layer 3 of body 4
has a transparent insulating layer on the insulating layer 3 of FIG.

The distribution shape of R2O, B filters, etc. in the filter layer 3a of the insulating layer 3 is not particularly limited, but the stripe-like distribution shown in FIG. 5 is used for easy pattern formation, and the shape shown in FIGS. The mosaic distribution shown is suitable for reproducing delicate multicolor images. And R,G,
The individual size of the B filter etc. is the length 10 shown by t in the figure.
A range of 200 μm to 200 μm is suitable from the viewpoint of image resolution, color reproducibility, ease of forming a distribution pattern, etc.

In the copying machine shown in FIGS. 8 and 9, a charger 5 and an image exposure device M6 are arranged around a drum-shaped photoreceptor 4 having a color separation function member such as an insulating layer 3 including a filter layer 3a as described above. ,
Uniform exposure device 7BT7G.

7R or further 7, non-contact development in which a -component or two-component developer is formed in a layer thickness that does not contact the surface of the photoreceptor 40, and an AC bias is used as a development bias to cause toner to fly from the developer layer. Developing devices 8Y, 8
M, 80.8K, or a discharger 9.9Y, 9M for smoothing the surface of the photoreceptor 40 after image exposure or development;
90. A transfer pretreatment device 10 using an exposure lamp for white light or infrared light that can pass through even a single layer of toner and a corona discharger, a transfer device 11, a separator 12, or further a static elimination lamp and a corona discharger. A pre-cleaning static eliminator 13 and a cleaning device 14 are provided to form a color image on the photoreceptor 4 through the steps shown in FIG.

FIG. 10 shows an example in which an n-type semiconductor photoconductor such as cadmium sulfide is used for the photoconductive layer 2 of the photoreceptor 4, but a p-type semiconductor such as selenium is used. However, the basic process of forming a color image remains the same, except that the positive and negative signs of the charges in the following explanation are all reversed. In FIG. 10, the same reference numerals as in FIGS. 1 to 9 indicate the same functional members.

Formation of color images in the copying machines of FIGS. 8 and 9 is performed as described below. The photoreceptor 4 rotates in the direction of the arrow in FIGS. 8 and 9, and the charger 5 uniformly charges the surface of the photoreceptor 40 by positive corona discharge as shown in FIG. 10 [1]. . That is, a positive charge is generated on the surface of the insulating layer 3, and a corresponding negative charge is induced at the interface between the photoconductive layer 2 and the insulating layer 3. As shown in , it shows a uniform potential. If it is difficult to inject charges into the photoreceptor 4 during this charging, uniform irradiation with white light may also be used.

The image exposure device 6 makes an image exposure beam incident on the charged surface of the photoreceptor 40 . At this time, the discharger 61 simultaneously performs corona discharge of alternating current or direct current of opposite sign to that of the charger 5. 10th
Figure [2] shows an example of the red image exposure IR of an image exposure worker.
It shows the change in charging state due to That is, since the red image exposure IR passes through the R filter portion of the insulating layer 3 and makes the portion of the photoconductive layer 20 below it conductive, the insulating rf! The negative charge at the interface with i3 disappears. On the other hand, since the G and B filter portions do not transmit the red image exposure IR, the negative charges of the photoconductive layer 2 remain in those portions. The same applies to other color components of image exposure.

In this manner, a primary latent image is formed on the interface between the insulating layer 3 and the photoconductive layer 2 by charge density corresponding to the color components of each filter. In this case, due to the action of the discharger 61 of the image exposure device 6, regardless of the amount of charge on the interface between the insulating layer 3 and the photoconductive layer 2, that is, regardless of whether image exposure is applied or not, the photosensitive layer is exposed. It is important that the surface potential of the body is smoothed as seen in the potential E graph. It is discharger 610
This is achieved by distributing the charge on the surface of the photoreceptor so as to balance it with the charge on the interface, so that the latent image does not function as an electrostatic image. This is conventional
This was not a problem with the P or KIP method, but in the method of the present invention, as explained below, a potential pattern is formed on a specific filter part using specific light and developed, so this potential smoothing is ensured. There is a need to do. For this purpose, the copying machine shown in FIG. 9 is provided with a discharge device 9 for smoothing in addition to the discharge device 61 of the image exposure device 6 to ensure smoothing. The image exposure device N6 is not limited to the original reflection type, and may be of the transmission type, even if either the optical system or the document table is of a reciprocating type or an original passing type.

Next, the uniform exposure device 7B uniformly applies the blue light LB to the above-mentioned primary latent image forming surface. FIG. 10 [3] shows the change in the charging state due to this. In other words, the blue light LB does not pass through the R and G filter parts, so it does not change those parts, but it passes through the B filter part and makes the photoconductive layer 2 below it conductive, thereby causing its change. The charges at the upper and lower interfaces of the photoconductive layer 2 in the portion are neutralized, and as a result, the potential pattern, that is, the electrostatic image that gives the surface of the insulating layer 30 a complementary color image of blue in the previous image exposure, is It appears as shown in the graph of E.

This electrostatic image is developed by a developing device 8Y containing yellow toner that is negatively charged by friction. FIG. 10 [4] shows the developed state. That is, yellow toner TY is
It adheres only to the B filter portion where the potential has changed due to uniform exposure with the blue light LB, and does not adhere to the R and G filter portions where the potential has not changed. As a result, a yellow toner image is formed on the surface of the photoreceptor 40. Although the potential of the portion of the B filter to which the yellow toner TY is attached is lowered by development, the surface potential is not uniform as seen in the graph of the potential E.

The surface of the photoreceptor 40 on which this yellow toner image is formed is
In the copying machine shown in FIG. 8, after passing through the position from the developing device 8M, which is placed in an inoperable state so as not to damage the toner image, to the charger 5, and reaching the position of the discharger 61 again, the discharger 61 discharges, lowering the potential of the B filter portion of the photoreceptor 4 on which the yellow toner image is formed and smoothing the surface potential, as shown in particular in the potential E graph in FIG. 10 [5]. In the copying machine shown in FIG. 9, the surface of the photoreceptor 4 on which the yellow toner image is formed is smoothed by a discharger 9Y.

The uniform exposure device 7G uniformly applies green light LG to the surface of the photoreceptor 4, on which the yellow toner image has been formed and the surface potential has been made uniform. As a result, a potential pattern appears in the G filter portion, similar to that described in FIG. 10 [3]. When this potential pattern is developed by the developing device 8M containing magenta toner, the magenta toner adheres only to the G filter portion and a magenta toner image is formed as in FIG. 10 [4]. As a result, two-color toner images are combined on the photoreceptor. Further, the discharger 61 in the copying machine shown in FIG. 8 and the discharger 9M in the copying machine shown in FIG. 9 discharge electricity on this image forming surface to smooth the surface potential. Subsequently, the uniform exposure device 7R uniformly applies red light LR to this image forming surface. However, when the image exposure process is red image exposure IR, no potential pattern appears in the R filter portion, and therefore no cyan toner adheres even if development is performed with the developing device 8C that stores cyan toner. That is, for red image exposure IR, a red image is formed by combining a yellow toner image and a magenta toner image. Similarly, for green image exposure and blue image exposure, a green image is formed by combining a cyan toner image and a yellow toner image, and a blue image is formed by combining a cyan toner image and a magenta toner image, respectively. Therefore, when the image exposure is full color image exposure, a full color image is formed by combining yellow and magenta cyan toner images.

As a result, a clear color image is formed on the photoreceptor 4 without any color shift or uneven color. Table 1 shows the relationship in which the colors of the original image are reproduced by the above image forming process.

In Table 1, the symbol "ζ-shaped" indicates the -order latent image, the symbol "○" indicates the formation of a potential pattern, that is, an electrostatic image, the symbol "■" indicates that a toner image has been formed, and the symbol "↓" indicates that the upper The state of the column is maintained as it is; a blank column indicates that no image exists.Also, "-" in the attached toner column.
indicates that there is no toner attached, and Y, M, and C are yellow toner! Magenta toner - Indicates that cyan toner is attached.

As can be seen from the above description, the original image can also be reproduced as a monochrome image in the image forming process shown in Table 1. However, the monochromatic image reproduced by the steps in Table 1 is
It is formed by toner of one color adhering to any one of the B, G, and R filter parts, or toner of different colors adhering to a plurality of filter parts, respectively.

On the other hand, when reproducing a monochrome image (the original image is not limited to a monochrome image), the uniform exposure device 7B, 7GI7
B by inputting blue light LB, green light LG, and red light IR one after another by H, or by inputting, for example, white light which produces a similar effect.

forming a potential pattern on the G and R filter portions at the same time t7;
Those potential patterns are developed by developing devices 8Y and 8M.

If the developing device 8 containing toner 8C and black toner is used for development, the toner of the negative color may adhere to any of the B, G, and R filter portions, and the monocolor copying machine According to the method, it is possible to form a monochromatic image with the same image density and resolution. In the copying machine shown in Fig. 8, such a monochromatic image can be formed within one revolution of the photoreceptor 401, but in the copying machine shown in Fig. 9, even though monochromatic images of cyan and black are formed within one revolution, yellow and magenta images are formed within one revolution. A monochromatic image will be formed by multiple rotations. However, if a white light lamp and a filter FB that transmits blue light as shown in FIG. 1θ [3] are used in the uniform exposure device 7B of the copying machine in FIG.
If the filter FB is made retractable and the filter FB is retracted when forming a monochrome image, the copying machine shown in FIG. Also, instead of the uniform exposure devices 7B, 7G, and 7H of the copying machine shown in FIG.
When forming a monochromatic image using a uniform exposure device consisting of filter switching means that transmits green light, red light, and white light, white light is applied to the surface of the photoreceptor 4 on which the -order latent image has been formed. The uniform exposure may be performed.

Table 2 shows the state in which a monochrome image is formed using a single color toner through the above monochrome image forming process.

In Table 2, the same symbols as in Table 1 indicate the same contents.

In the monochrome image forming process shown in Table 2, monochrome images other than black are yellow, magenta, and two cyan. However, after black, the most commonly desired monochromatic image is red, followed by blue. If red, blue, and green toners are used to reproduce a full-color image, a single-color image of red, blue, and green can be formed using the steps shown in Table 2, but yellow, magenta, and cyan toners are generally used. . Therefore, even if yellow, magenta, and cyan toners are used, red, blue, and green monochrome images with the same image density and resolution as the monochrome images in Table 2 can be obtained. yellow.

The surface of the photoreceptor 40 on which magenta and cyan monochrome images are formed is superimposed and developed by another developing device. Thereby, another color toner is deposited on top of the single color image of magenta, yellow, cyan, and red with similar image density and resolution according to the monochrome copier.

A monochrome image of blue and green can be formed. This takes advantage of the fact that even when toner adheres, the surface position of the photoreceptor 40 does not drop uniformly in that area, as shown in the potential E graph in Figure 1θ [4]. Development by another developing device is performed on the previous toner image forming surface without smoothing the surface potential. Table 3 shows the process of forming this overlapping image. In Table 3, the same symbols as in Table 1 indicate the same contents.

A multicolor image formed by combining a plurality of toner images formed on the photoreceptor 4 through the above steps, a monochrome image formed by -color toner, and a monochrome image formed by superimposing two-color toners are as follows:
The transfer device 11 is applied to the transfer material P which is made easy to be transferred by the transfer pre-processing device 10 and is fed by the feeding means 15.
The transfer material P on which the multicolor image and monochrome image have been transferred is separated from the photoreceptor 4 by the separator 12 and sent to the fixing means 17 by the conveying means 16, where the multicolor image and the monochrome image are transferred. The monochrome image is fixed and ejected from the machine. The surface of the photoreceptor 4 to which the toner image has been transferred is charged, if necessary, by a pre-cleaning static eliminator 13 as shown in FIG. The remaining toner is then removed, and the state returns to the initial state where the next image formation is performed. As is clear from the above explanation, in the copying machine shown in FIG. 8, a multicolor image is formed by multiple rotations of the photoreceptor 4, and in the copying machine shown in FIG. 9, it is formed within one rotation of the photoreceptor 4. Ru. Also, the discharger 9 in FIG.
C and uniform exposure device fi7 are used for surface potential smoothing, which is used when forming a black monochrome image or when developing in the developing device 8 at the end to increase the contrast of a color image. This is a uniform exposure device in which light passes through a discharger for the purpose of the present invention and each color separation filter of the photoreceptor 4.

The gradation of the image formed and recorded as described above is changed by changing the image exposure and discharge by the image exposure device 6 as shown in FIGS. 11.12, 14.15, 17, and 19. This is done by relatively changing the above means or a combination of two or more of these means. These means, as one structure of the discharge device 61 for potential smoothing, have a plurality of discharge wires, and discharge is performed at a position biased toward the downstream side of the rotation of the photoreceptor 4.

This improves the effect of potential smoothing, but still
As in the copying machine shown in the figure, a discharger 9 is further provided on the downstream side to ensure potential smoothing.・By biasing the incident position to the discharger 61 toward the upstream side of the rotation of the photoreceptor 4, a high contrast image is obtained, and by biasing it toward the downstream side, a gradation image is obtained. It is something. That is, when the incident position of the image exposure process is biased to the upstream side of 40 rotations of the photoreceptor, the relationship between the exposure amount Q and the potential E of the potential pattern obtained by uniform exposure for each color component of the image exposure process becomes the 12th
As shown by curve Al in the figure, the γ value changes to a high state,
On the other hand, if the image exposure 10 incident position is shifted to the downstream side,
Since the γ value changes to a low state as shown by the curve Bl in FIG. 12, the gradation can be changed as described above. The movable slit 62 may not be used to change the incident position of the image exposure 10, but the reflection angle of the image exposure incident mirror 630 shown in FIGS. 8 and 9 may be changed.

As shown in FIGS. 14 and 15, the position of the upstream discharge wire 61W of the discharge device 61 is moved to the downstream and upstream sides of the rotation of the photoreceptor 4. Also, the relationship between the exposure amount Q and the potential pattern potential E is the first.
Since the curves A2 and 82 in FIG. 6 change, it is possible to obtain a high contrast image and a gradation image.

In addition, the incident position of the image exposure process and the discharge wire 6 of the discharge device 61
Instead of changing the position of 1W, as shown in Figure 17,
When the photoreceptor 4 is substantially negatively charged, the gradation can also be changed by changing the voltage applied to the side plate 61S of the discharger 61 on the upstream side of the photoreceptor 4. That is, by setting the absolute value of the voltage applied to the side plate 61S1 to a large value, and vice versa, by setting it to a small value, the exposure ff1 of each component of the image exposure process is
The relationship between Q and the potential pattern potential E can be changed as shown by curves A3 and B3 in FIG. 18, and therefore a high contrast image and a gradation image can be obtained.

In addition, to change the side plate voltage, as shown in FIG. 19, the grid of the discharger 61 is divided into 6101 on the upstream side and 6102 on the downstream side of 40 rotations of the photoreceptor.
By increasing or conversely decreasing the absolute value of the voltage applied to the upstream grid 61G1, the relationship between the exposure ftQ and the potential pattern potential E can be changed as shown by curves A4 and B4 in FIG. 20. Therefore, a high contrast image and a gradation image can be obtained.

Changing the gradation of an image using the above method can be done by stepless operation of the gradation operation member, or can be done by switching with a designated button depending on whether the original is a line drawing or a gradation drawing. It can also be done.

The present invention also relates to the image forming method described in Japanese Patent Application No. 199547, which uses a photoreceptor provided with a filter on the basic side, and the image forming method described in Japanese Patent Application No. 59-1995, which uses a photoreceptor whose photoconductive layer has a color separation function. It can also be applied to the image forming method described in No. 201085. That is, these image forming methods also form a primary latent image by charging performed simultaneously with image exposure.

〔Effect of the invention〕

According to the present invention, color images can be produced without color shift or color turbidity.
In addition, it has the excellent effect of being able to form monochrome images with the same image density and resolution as using a photoreceptor without a color separation function member, and also being able to easily change the gradation of those images. It can be played.

[Brief explanation of drawings]

1 to 4 are schematic partial sectional views showing examples of the layer structure of the photoreceptor used in the present invention, and FIGS. 5 to 7, respectively.
Figures 8 and 9 are partial plan views showing examples of the distribution shape of color separation filters in the filter layer of the photoreceptor, respectively.
The figures are a schematic configuration diagram showing an example of a copying machine implementing the present invention, Figure 0 is a process diagram showing the principle of color image formation,
Figures 11, 12, 14115, 17, 19, 13, 16, 18, and 20 respectively show relative image exposure and discharge in the primary latent image forming step. 2 is a schematic diagram of an image exposure portion showing examples of changing methods, and a graph showing a relationship between the exposure amount and electrostatic image potential obtained by those methods. DESCRIPTION OF SYMBOLS 1... Conductive member, 2... Photoconductive layer, 3...
...Insulating layer, 3a...Filter layer, R,
G, B...filter part, 4...photoreceptor, 5...charger, 6...
・Image exposure device, 61...Discharger, 61W...
・Discharge wire, 61S+? 61S2...side plate, 61G+
+ 6102... Grid, 62... Movable slit, 63... Image exposure incident mirror, 7B, 7
G, 7R, 7K...-Kiln operation light device, 8Y, 8
M, 80, 8K...Developing device, 9, 9Y,
9M, 9G--discharger. Patent applicant: Konishi Roku Photo Industry Co., Ltd. Agent: Patent attorney: Haru Yasushi. Fig. 1 Fig. Z Fig. 3 Fig. Li Fig. 5 Fig. 6 Fig. δ Fig. 11 Fig. 14 Nozzle 1z Fig.
15th Series Figure 13 Figure f6

Claims (5)

[Claims] (1) A photoreceptor having a color separation function member and having an insulating layer on the surface is subjected to a uniform charging process by electric discharge, and a primary latent image forming process by image exposure and electric discharge, and then uniformly exposed to specific light. In a method of forming a color image by repeating an electrostatic image forming step using a method and a developing step using color toner, the gradation of the formed image can be changed by relatively changing the image exposure and discharge in the primary latent image forming step. 1. A color image forming method, characterized in that color image formation is controlled. (2) A color image forming method according to claim 1, wherein the relative change between the imagewise exposure and the discharge is provided by changing the incident position of the imagewise exposure onto the photoreceptor using a slit mechanism. (3) The color image forming method according to claim 1, wherein the relative change between the image exposure and the discharge is provided by moving the position of the discharge wire. (4) A color image forming method according to claim 1, wherein the relative change between the image exposure and the discharge is provided by changing a bias voltage applied to a side plate of a discharge device. (5) The method according to any one of claims 1 to 4, wherein the relative change between the image exposure and the discharge is performed based on a designation by a designation operation means such as image gradation. Color image forming method.