JPS6034748B2 - Electrophotographic forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides electrophotography in which a static latent image is formed on a recording medium according to image information obtained by combining a plurality of image information, and this static latent image is developed with toner. This relates to a forming method.

In general, the subtractive color method is widely adopted in color electrophotography, in which a color document is separated into blue, green, and red images using a three-color separation filter, and corresponding toners, ie, yellow toner, and The image is developed using magenta toner and cyan toner, and the images formed by each toner are substantially superimposed to obtain a copy image that reproduces the color original.

However, since the light absorption characteristics of the toner are not ideal, it is not possible to obtain a copy image that faithfully reproduces a color original by simply superimposing the toner images.

For example, when reproducing a color original 1 consisting of a yellow area Y, a red area R, and a reddish-purple area M as shown in FIG.
The red region R is reproduced by a mixture of a yellow toner and a magenta toner, and the reddish-purple region M is reproduced by a magenta toner, but the blue light that should be absorbed only by the yellow toner is also absorbed by the magenta toner. Therefore, the reproduced image of the red region R becomes yellowish. In order to prevent this, it is sufficient to deposit an amount of yellow toner that is the amount of yellow toner that should be deposited according to the blue separation image, minus the amount corresponding to the blue light absorption that occurs according to the amount of magenta toner deposited. However, in order to easily perform this color tone correction, it is necessary to form a static exposure latent image on the recording medium to be developed by adhering yellow toner, the surface potential of which is controlled in accordance with the correction. is necessary.

That is, as shown in FIG. 2, after the surface of the recording medium 2 having a photoconductive layer is uniformly charged, the yellow area Y and the red area R in FIG.
However, as shown in FIG. 3, the potential V of the part corresponding to the red area R is greater than the potential V2 of the part corresponding to the yellow area Y, so that the magenta toner adhesion amount, that is, the green separated image It is necessary to form a static exposure latent image that is lower by a magnitude d that is inversely proportional to the exposure amount. In the figure, the magnitude of the potential is conveniently indicated by the density of 10 or -. However, it is theoretically impossible to obtain an electrostatic latent image in which two pieces of image information are superimposed so as to cancel each other out as shown in Figure 3.
It is actually very difficult.

For example, in order to form a static latent image for forming a yellow toner image with the above-mentioned correction, theoretically, after charging the recording medium, exposure of a positive image of a blue separation image and exposure of a negative image of a green separation image are performed. However, in practice it is extremely difficult to expose negative images. Moreover, even if one directly converts the original into a negative image or uses reversal development to achieve substantially the same result as the exposure of the negative image, exposure of the positive image is also necessary. Since the image must have a negative-positive relationship, reversal exposure is essential in both cases. It is difficult to perform this reversal exposure using ordinary optical means. SUMMARY OF THE INVENTION An object of the present invention is to provide a method that eliminates the above-mentioned drawbacks and can extremely easily form an electrostatic latent image corresponding to a superposition of a plurality of pieces of image information in a destructive manner. It is a further object of the present invention to produce electrostatic latent images of the same color tones as those obtained when two three-color separation images of a color original are subtractively exposed onto the same photoconductive layer. It is an object of the present invention to provide a method that can extremely easily form a corrected copy image as it is.

Embodiments of the present invention will be described below with reference to the drawings.

First, the photoconductive ion flow control grid (hereinafter referred to as "screen") used in the present invention will be explained.
Generally, as shown in FIG. 4A, when one side of a mesh 4 having a large number of through holes 3 is charged positively and the other side is charged negatively, a green electric field is generated in the space inside the through holes 3. Ori,
Charged particles (ions) directed to pass through the through-holes 3 are affected by the strength and direction of this electric field. For example, when positive ions are irradiated from one side of the net-like body 4, these ions pass through the through-holes 3. It passes through the hole 3 and escapes to the other side, but in the case of anions, they are attracted to the positive charges on the one side and their bonds disappear, and they cannot pass through to the other side. On the contrary, if ions are irradiated from the other side as shown in FIG. 4B, cations will be blocked and anions will pass through. The amount of ions that pass through varies depending on the strength of the green electric field, that is, the amount of charge on the network 4 and the magnitude of the electric field that promotes the ions to pass through the through holes 8. FIG. 6 shows an example of a screen that controls ion flow based on the principle described above and can be suitably used in the present invention.

This screen 5 has a first photoconductive layer 7 provided on one surface of a base 6 made of a metal grid having a large number of through holes, and a first photoconductive layer 7 on the other surface separated from the first photoconductive layer 7. Two photoconductive layers 8 are provided. Hereinafter, an example will be described in which an electrostatic image including a color tone correction to be developed with yellow toner is formed.

In the present invention, as shown in FIG. 6, both the first photoconductive layer 7 and the second photoconductive layer 8 of the screen 5 are uniformly negatively charged, and the first photoconductive layer 7 is The image of the color original is exposed through a blue filter to form a positive electrostatic image of a blue separated image due to negative charges, and the image of the color original is exposed to the second photoconductive layer 8 through a green filter. , and are exposed to light so as to have a mirror image relationship with the electrostatic image of the blue separated image, thereby forming positive electrostatic images of the green separated image due to negative charges. Next, an ion source 9 is placed so as to face the second photoconductive layer 8 of this screen 5, and a conductor 10 is placed so as to face the first photoconductive layer 7.
A recording body 12 having an insulating surface layer 11 provided thereon is arranged,
While the conductor 10 of the recording body 12 is kept at a negative potential lower than the base 6 of the screen 5 by the power source 13,
The power source 14 causes the ion source 9 to emit intestinal ions 15 while scanning. In this way, a desired static exposure latent image is formed on the insulating surface layer 11 of the recording medium 12.

That is, if no electrostatic image is formed on the second photoconductive layer 8 of the screen 5, the positive ions 15 will be transferred to the first photoconductive layer 7.
The electrostatic image formed on the screen passes through the screen 5 in an amount that increases or decreases depending on the amount of charge, and a positive electrostatic image of a blue separated image due to positive charges is formed on the insulating surface layer 11. In addition, if no electrostatic image is formed on the first photoconductive layer 7, the amount of cations 15 decreases or increases depending on the amount of charge of the electrostatic image on the second photoconductive layer 8. Since the light passes through the screen 5, a negative electrostatic image of a border color separation image due to positive charges should be formed on the insulating surface layer 11. Actually, since the above two electrostatic image formations are performed simultaneously, 15 cations are generated in the area corresponding to the yellow area Y of the color original.
passes freely and in a suppressed state in the region corresponding to the red region R, and the intestinal ions 15 are blocked in the region corresponding to the reddish-purple region M. Therefore, the electrostatic charge in the potential state shown in FIG. A latent image is formed. As a result, by developing this static lightning latent image with yellow toner, it is possible to obtain a yellow toner image in which the amount of blue light absorbed by the magenta toner is corrected.

Further, in the present invention, as shown in FIG.
An electrostatic image of a green color separation image of a color original is formed by positive charges on the first photoconductive layer 7 of the photoconductive layer 7 , and the recording medium 12 is disposed so as to face the first photoconductive layer 7 . '
An ion source 9 and an exposure mechanism 16 are disposed so as to face the second photoconductive layer 8 of the screen 5, and the image of the color original is exposed to the second photoconductive layer 8 of the screen 5 by the exposure mechanism 16. The intestinal ions 15 may be emitted from the ion source 9 and scanned while being exposed to light through a blue filter.

In this case, the second photoconductive layer 8 of the screen 5 is charged by being irradiated with positive ions 15 from the ion source 9 and at the same time is exposed to the blue separated image. An electrostatic image of the blue separation image due to charges will be formed.

Therefore, the insulating surface layer 11 of the recording medium 12 has a static latent image in which a positive electrostatic image of a green separated image due to positive charges and a positive electrostatic image of a blue separated image due to positive charges are superimposed, as in the case of FIG. It is formed. As detailed above, according to the electrophotographic forming method of the present invention, it is possible to form, on a recording medium, an electrostatic latent image in which electrostatic images of two types of images are superimposed in a destructive manner by an extremely simple method. By applying it to the formation of color electrophotography, it is possible to easily obtain a static exposure latent image that has been corrected in accordance with the color tone correction, and therefore it is easy to make a color copy image that has undergone color tone correction and faithfully reproduces the original. There are extremely large benefits such as the ability to obtain

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a color original; FIGS. 2A and 2B are schematic explanatory diagrams and graphs showing the potential state of a static lightning latent image that does not include correction corresponding to color tone correction, corresponding to FIG. Figure 3A
and B are views of the same aircraft as in FIGS. 2A and B, respectively, regarding static exposure latent images including the above-mentioned corrections, FIG. 4 is an explanatory diagram showing the operating principle of the screen used in the present invention, and FIG. FIGS. 6 and 7 are explanatory cross-sectional views showing an example of a screen to be obtained, and are explanatory views showing an embodiment and other embodiments of the electrophotographic forming method of the present invention in conjunction with FIG. 1. 1...Color original, 2...Record, 4...
... Reticular body, 5 ... Screen, 6 ... Base, 7
, 8... Photoconductive layer, 9... Ion source, 12
・・・・・・Record body. Atsushi! Figure Moat 2nd Edition Madarucha 4th Edition Pseudo S Figure 6th Anniversary Figure 7

Claims (1)

[Scope of Claims] 1. Both photoconductive layers of an ion flow control screen having photoconductive layers on both sides are charged with charges of the same polarity, and both charged photoconductive layers are charged with charges of the same polarity. By exposing the recording body to the image information and the second image information, placing the recording body facing the exposed screen, and irradiating the recording body with ions through the screen, an electrostatic charge is generated on the recording body. An electrophotographic forming method characterized by forming a latent image and developing this electrostatic latent image with toner. 2. The first image information and the second image information are one and the other of three-color separation image information of a color original, respectively, and the photoconductive layer of the screen facing the recording medium is exposed by the one of the three color separation image information,
The electrophotographic forming method according to claim 1, wherein the toner is a toner corresponding to the one of the three color separation image information.