JPS6319674A - Formation of two-color image - Google Patents

Abstract

PURPOSE:To obtain a copy image wherein the black image part of an original is erased optionally and partially by controlling a light emitting means which emits light selectively and partially with a signal from an image area specifying means and exposing the entire surface except a specified area in an entire-surface exposing process. CONSTITUTION:Positive corona discharging is carried out by the tertiary scorotron charger 11 and then the entire surface except the specified area is exposed by an LED array 12. Namely, when a part corresponding to the specified area passes, the LED array 12 is turned off partially with the signal from the image area specifying means and when other parts pass, the LED array is turned on continuously. Therefore, positive charges at a black image corresponding part which are held between a dielectric layer (I) and a photoconductor layer (II) except in the specified area leak through a conductor base layer (III) except charges which are restrained by surface charges of the dielectric layer (I) when the electric resistance of the photoconductor layer (II) decreases, so that the surface potential corresponding to the black image area outside the specified area decreases to the negative side. Consequently, the two-color copy image is obtained while the black image part of the original is erased optionally and partially.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-color image forming method using an electrostatic recording method.

Prior art and its four problems Conventionally, as a method for obtaining a two-color copy image corresponding to an original image composed of two colors, black and chromatic colors,
A method described in Japanese Patent No. 34305 is known. That is,
The surface of a photoreceptor having an insulating layer, a light guide layer, and a conductive layer is uniformly charged, and a light image that blocks chromatic colors is irradiated onto the surface of the photoreceptor, and at the same time, a discharge with a polarity opposite to that of the charging is applied. A light image having a chromatic color to be reproduced is irradiated on the surface of the photoreceptor in a superimposed manner on the above-mentioned light image, and a predetermined developer is applied to the surface of the photoreceptor to perform first development. This is an electronic 7-way development method in which second development is performed by irradiating light and providing a developer of a different color from the first development. In this method, (1
) In addition to obtaining a copy image that corresponds one-to-one to the two-color original image, by controlling the light image irradiation process that blocks chromatic colors, the static electricity removal process, and the light image irradiation process that has chromatic colors, (i ) All black copy images, (i) All chromatic color copy images, (i
v) It is possible to obtain a copy image in which the black image portion of the original is deleted, and (V) a copy image in which the chromatic color image portion of the original is deleted.

However, this method has the problem that it is not possible to obtain a copy image in which the black image portion of the original is arbitrarily and partially erased.

Means for Solving the Problems Therefore, the two-color image forming method according to the present invention provides: A charging step in which a uniform charge is applied, a chromatic cut image exposure step in which a corona discharge or an alternating current corona discharge of opposite polarity to this charging step is applied, and at the same time image exposure is performed through a chromatic complementary color filter; A chromatic image exposure process in which image exposure is performed through a filter, a chromatic development process in which a chromatic latent image area is developed with chromatic toner, and a chromatic image carrier surface that holds a chromatic toner image. , a static elimination process in which a corona discharge or an alternating current corona discharge with a polarity opposite to that of the charging process is applied, an entire surface exposure process in which the surface of the electrostatic latent image carrier that has undergone this static elimination process is uniformly irradiated with light, and a black toner is A two-color image forming method comprising: a black developing step of developing a black latent image portion using a light emitting device; It is characterized by the following: Controlled by a signal, the entire area outside the designated area is exposed.

In the methods above, the black image area outside the designated area is covered by exposing the entire area outside the designated area as a full exposure step that is performed immediately after the chromatic color development step and the subsequent static elimination step. Although the surface potential of the portion increases, the surface potential of the portion corresponding to the black image portion within the designated area does not increase, and such black image portion within the designated area is developed in the next black developing step. It never happens.

Hereinafter, an embodiment of the two-color image forming method according to the present invention will be described with reference to the accompanying drawings. However, in this example,
This will be explained using red, which is the most commonly used chromatic color, as an example.

FIG. 1 shows the overall structure of an electrophotographic copying machine for carrying out the present invention, in which a drum (1) having an electrostatic latent image carrier on its outer periphery is driven to rotate in the direction of arrow (a) approximately in the center. Possibly installed. As shown in Figure 2, the electrostatic latent image carrier has a transparent dielectric layer (I) on the surface, a photoconductor layer (II) in the middle, and is based on a conductor support FIJ (III). The conductor support layer (I[[) is grounded.

Around this drum 1), eraser lamps (
2), a primary Sufrotron charger (3), a red cut filter (5), and a second with a red filter (6).
Next, a scorotron charger (7), a magnetic brush type developing device (10) containing a developer containing red toner, and a third
Next Sufrotron charger (11), LED array (
12) A magnetic brush type developing device (14) containing a developer containing black toner, a transfer charger (15), a separation charger (16), and a blade type residual toner cleaning device (17) have been installed. .

The eraser lamp (2) is used on the drum (1) at the final stage of the copying operation.
) The purpose is to erase residual charges on the surface, but the inside of the shield plate of the primary Sufrotron charger (3) is also exposed at the start of the copying operation.

An opening (7a) is formed in the shield plate of the secondary Sufrotron charger (7), and a red cut filter (5)
faces the opening (7a), and a red filter (6>) is installed adjacent to the shield plate.A light image from the image exposure device (20), which will be described below, is captured by the filter (5).

(6) and the red cutoff filter 5) reaches the surface of the drum (1) together with the corona discharge of the secondary scorotron charger (7).

The LED array (12) includes a plurality of light emitting diodes (LE
D) are arranged in parallel in the width direction of the drum (1), and each light emitting diode is lit to expose the entire area outside the designated area. The designated area is a characteristic main part of the present invention,
For example, as in the designated area (X) shown in FIG. ) refers to the area to be copied as is as a red copy image part (R1). Furthermore, the black image part (BL,') and the red image part (R,') other than the designated area (X) of the original image (S, ) ) is the copied image part (BL!') that is black as it is.

It is copied as a red copy image portion (R*'). L.E.
The blinking of the D array (12) is controlled by a signal from an image area specifying means consisting of a switch on the operation panel (not shown) of the copying machine body, and in the width direction (y+), each light emitting diode is turned on and off. Accordingly, the imaging direction (Y, )
This is done by controlling the lighting time of each light emitting diode.

Image exposure device 1! (20) adopts the well-known slit exposure method with a moving optical system, and the exposure lamp (21)
, mirror (22), (23), (24), projection lens (25).

It consists of mirrors (26), (27), and (28).

On the other hand, the copy paper is fully accommodated in the automatic paper feed cassette (30), and is fed one sheet at a time from the top layer by a paper feed roller ruff 31), and is fed by a pair of timing rollers (32) to a drum ( It is conveyed between the drum (1) and the transfer charger (15) in time with the image formed on the surface of the drum (1). Here, the toner image is transferred, sent to the fixing device (34) by the air suction belt (33), where the toner is fixed, and then discharged onto the tray (36) from the discharge roller pair (35). .

Here, the specific conditions of the copying experiment conducted by the present inventors will be explained.

The dielectric layer (I) constituting the electrostatic latent image carrier has a thickness of 10 to 2
Insulating transparent materials such as 0μm acrylic and polyethylene terephthalate, photoconductors! <IF) is 50-100μ thick
m of selenium arsenic (As*5-s). When using acrylic, use dipping or spraying.
Polyethylene terephthalate is also attached by the same method, or by covering the selenium deposition drum with a heat-shrinkable type. The rotational peripheral speed of drum (1) is 130 mm/se
It is c.

Further, the primary Suflotron charger (3) has the ability to charge the surface of the driver (1) to -1500 to 2000V, and the secondary Suflotron charger (7)
performs a positive corona discharge and generates a primary suflotron.
Drum (1) negatively charged by charger (3)
It has the ability to eliminate the surface potential of approximately Ov. The tertiary scorotron charge (11) performs a positive corona discharge, and its grid voltage is set to 0 to +100V.

Next, the copying process in the copying machine having the above configuration will be explained for each copying mode with reference to FIG.

[Specified area black erasure mode] This copy mode is a copy mode achieved for the first time by the present invention, and a copy image is created in which the black image portion within the designated area is erased.

First, the entire surface of the drum (1) is exposed to light by the eraser book 2), and at the same time, a negative corona discharge is performed by the primary sufrotron charger (3). With this, as shown in FIG. 3 (A), the surface of the dielectric layer (I) is fully charged to 12000V, and the gap between the dielectric layer (I> and the photoconductor layer (I)) A positive charge is induced.

Next, positive polarity corona discharge is performed by the second scorotron charger <7>, and red cut image exposure is performed by the exposure device (20) via the red cut filter (5). In this way, as shown in FIG. 3 (B), the surface of the dielectric layer (I) is neutralized to approximately Ov, and only the white part (background part) of the original is exposed to light, which corresponds to the white part. As the electrical resistance of the photoconductor layer (II) decreases, the positive charge held between the dielectric layer (I) and the photoconductor layer (If) is transferred to the conductor support layer (m ) is leaked via. Charges are retained between the dielectric layer (1) and the photoconductor layer (I[) corresponding to the black and red image areas that are not exposed to light.

Next, a red image exposure is performed through a red filter (6). As shown in FIG. 3 (C), the red image area of the original is fully exposed and is held between the dielectric layer (1) and the photoconductor Jl (If') in the previous process. The positive charge in the area corresponding to the red image area decreases in the electrical resistance of the photoconductor +W (II), so that the positive charge in the area corresponding to the red image area is reduced by the conductor support layer, except for those restricted by the surface charge of the dielectric layer <I). It is leaked via <m>. As a result, the surface potential of the drum 1) corresponding to the red image area increases to the negative side. The surface potential of the red image area here is -300 to 400 .

Therefore, regular development is performed by a developing device (10) using a developer containing positively triboelectrically charged red toner. As a result, red toner (rr) adheres to the red image portion, as shown in FIG. 3(D).

Next, a positive corona discharge is performed by the tertiary suflotron charger (11). As a result, as shown in FIG. 3(E), the surface potential near the red toner is reduced to approximately 0.

Subsequently, the entire surface outside the designated area is exposed by the LED array (12). That is, when the portion corresponding to the designated area passes by the signal from the image area designating means,
The LED array (12) is partially turned off and remains lit when other parts pass. With this, as shown in FIG. 3 (F), the dielectric layer (I>, the photoconductor, 1
The positive charge in the area corresponding to the black image area outside the designated area, which was held between leakage occurs through the conductor support layer (III) except for those restricted by the conductor support layer (III). As a result, the surface potential corresponding to the black image portion outside the designated area, which did not increase to the negative side in the above step, increases to the negative side. The surface potential of the black image portion here is -400 to 500 .

However, in designated areas that are not irradiated with light by the LED array (12), the positive charge held between the dielectric layer (I>, !: photophotoconductive layer deposited If) remains intact. . That is, the surface potential of the portion corresponding to the black image portion within the designated area does not increase at all and remains neutralized to 0.

Therefore, regular development is performed using a developer containing positively triboelectrically charged black toner using the developing device (14).As shown in (G) in FIG. Although the black toner (Tb) adheres to the portion, it does not adhere to the black image portion within the designated area.

Through the copying process described above, only the black image portion within the specified area is partially erased, and the remaining portions can obtain a two-color copy image corresponding to the black and red colors of the original.

[1-to-1 copy mode] This copy mode is a mode for obtaining a two-color copy image that corresponds one-to-one to the black and red of the original.

Here, the area for image deletion is not specified, and the third
The entire surface is exposed by I, ED play (12) indicated by CF> in the figure, and the other steps are the same as in the designated area black erasing mode. That is, when the entire surface is exposed by the LED array (12), the surface potential of the portion corresponding to the black image area within the designated area, which did not increase to the negative side in the above mode, also increases to the negative side, and the surface potential of the portion corresponding to the black image area increases to the negative side in the developing device (14). It will be developed.

[Black mode] This copy mode is a mode in which all images are copied in black, regardless of whether the original is black or red.

In this case, the red cut filter (5) and the red filter (6) are retracted from the optical path of the exposure device (20) to form an electrostatic latent image on the surface of the drum (1), and the red developing device ( 10) is turned off, and development is performed using only the black developing device (14).

[Red Mode] This copy mode is a mode in which all images are copied in red, regardless of whether the original is black or red.

In this case as well, the filter (6)
, (7) are retracted from the optical path to form an electrostatic latent image on the surface of the drum (1>), and development is performed using only the red developing device (10).

[Black Cut Mode] This copying mode is a mode in which all black image areas of a document are erased and only red image areas are copied in red.

Here, only the light image passed through the red filter (6) is exposed on the surface of the drum (1) to form an electrostatic latent image of only the red image area, and development is performed using only the red developing device (10). Let's do it.

[Red Cut Mode] This copy mode is the opposite of the black cut mode.
This is a mode in which all the red image parts of the original are erased and only the black image parts are copied in black.

Therefore, here, only the light image that has passed through the red cut filter (5) is exposed to the surface of the drum (1) to form an electrostatic latent image with the red image portion cut out, and the black developing device (14
).

Note that the two-color image forming method according to the present invention is not limited to the above embodiments, and can be variously modified within the scope of the gist thereof. In particular, as a copying device, in addition to the configuration shown in FIG.
, using a normal corona discharge charger instead of (11), or a charger (7) for eliminating static electricity;
An alternating current voltage may be applied to (11). Furthermore, when a low resistance material such as CdS is used as the photoconductor layer <11>, an eraser lamp (
The entire surface exposure according to 2) is not necessary.

As is clear from the above description, according to the present invention, an electrostatic latent image carrier comprising a transparent dielectric layer, a photoconductor layer, and a conductive support layer is used to produce a chromatic complementary color filter.

A light emitting means that performs image exposure through a chromatic color filter and is capable of selectively emitting partial light as a full-scale exposure step that is performed immediately after the chromatic image development step and the subsequent static elimination step is activated by a signal from the image area specifying means. Since the area outside the designated area is fully exposed under control, the surface potential of the part corresponding to the black image part within the designated area does not increase, and therefore, it is not completely developed in the next black developing process. It is possible to obtain a two-color copy image in which the black image portion of the original is arbitrarily and partially erased, which was previously impossible. Of course, as explained in the above embodiments, by partially changing each copying process of the present invention, it is also possible to execute a one-to-one copying mode or the like with the same copying apparatus.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an electrophotographic copying machine for carrying out the two-color image forming method according to the present invention, FIG. 2 is a sectional view of an electrostatic latent image carrier, and FIG. 3 is an explanatory diagram of a copying process. FIG. 4 is an explanatory diagram of color conversion. (I)...Dielectric layer, (n)...Photoconductor layer, (I
II) Conductor support layer, (1) Electrostatic latent image carrier drum, (2) Eraser lamp, (3) Primary Suflotron charger, (5)・Red cut filter, (6)...Red filter, (7)...
2nd Sufrotron charger, (10)...Red developing device, (11)...3rd Sufrotron fist charger, (12)...LED array, (14)...
Black developing device, (20)...image exposure device.

Claims (1)

[Claims] 1. A charging process in which the surface of an electrostatic latent image carrier consisting of a transparent dielectric layer, a photoconductor layer, and a conductive support layer is uniformly charged, and this charging process is reversed. A chromatic color cut image exposure step in which polar corona discharge or alternating current corona discharge is applied and, at the same time, image exposure is performed through a chromatic complementary color filter; a chromatic image exposure step in which image exposure is performed through a chromatic color filter; A chromatic development step in which a chromatic latent image area is developed with colored toner, and a corona discharge or alternating current corona discharge with a polarity opposite to that of the charging step is applied to the surface of the electrostatic latent image carrier holding the chromatic toner image. 2. A static electricity removal process, a full-surface exposure process in which the surface of the electrostatic latent image carrier that has undergone the static electricity removal process is uniformly irradiated with light, and a black development process, in which the black latent image area is developed with black toner. 2. A color image forming method, characterized in that, in the whole surface exposure step, a light emitting means capable of selectively emitting partial light is controlled by a signal from an image area designation means to expose the entire surface outside the designated area. Color image forming method.