JPS62291674A - Formation of two-color image - Google Patents

Abstract

PURPOSE:To change a black image part to a chromatic color part by forming a specified part exposing process for partially emitting a light emitting means simultaneously with an exposure process or immediately after the process based on a signal generated from an image area specifying means and irradiating a specified image area by light. CONSTITUTION:At the time of passage of a part corresponding to a specified area specified by a signal outputted from an image area specifying means, a LED array 8 is partially lighted. The positive polarity charge of a part corresponding to a black image part in the specified area held between a dielectric layer I and a photoconductor layer II is leaked through a conductor supporting layer III by reducing the electric resistance of a photoconductor layer II except a part restricted by the surface charge of the dielectric layer I. Thereby, the surface potential corresponding to the black image part of the specified area which is not increased to the negative side is increased to the negative side. Therefore, normal development is executed by a developer containing red toner triboelectrified to positive polarity by a developing device 10. Thus, red toner Tr is stuck to the black image part in the specified area together with the red image part.

Description

[Detailed description of the invention] 3. Detailed description of the invention and description of the invention are missing! The present invention relates to a two-color image forming method using an electrostatic recording method.

Prior art and its 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 photoconductive 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 electrophotographic method in which a second development is performed by irradiating light and using 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 a problem in that it is not possible to obtain a copy image in which the black image portion of the original is arbitrarily and partially changed to a chromatic color.

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 (b) a light emitting means that can partially emit white light or that can pass through a chromatic color filter is used to develop a black latent image portion in the image area; The image forming apparatus is characterized by comprising a designated part exposing step of emitting light partially at the same time as or immediately after the chromatic image exposing step to irradiate a designated image area with a signal from the designating means.

In the method described above, a designated image area on the surface of the electrostatic latent image carrier is irradiated with light at the same time as or immediately after the chromatic image exposure step, so that the black image area within the designated area is exposed to light. The charge of the corresponding part becomes the same as the charge of the part corresponding to the chromatic image part, and the black latent image part in such a designated area is converted into a chromatic latent image part with chromatic toner in the next tangible color development process. It will be developed together with the image.

EXAMPLE Hereinafter, an example of the two-color image forming method according to the present invention will be described with reference to the accompanying drawings. However, in this embodiment, red, which is the most commonly used chromatic color, will be explained 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. It is possible to install it. As shown in FIG. 2, the electrostatic latent image carrier has a transparent dielectric material vJ (I) on the surface and a photoconductor layer (If) in the middle.
The conductor support layer (III) is grounded.

Around this drum (1), eraser lamps (
2), a first order scorotron charger (3), a red cut filter (5), a second order scorotron charger (7) with a red filter (6), an LED array (
8), a magnetic brush type developing device (10) containing a developer containing red toner, and a tertiary Sufrotron charger (
11>, eraser lamp (12), magnetic brush type developing device containing developer containing black toner (14), transfer charger (15), separation charger (16), blade type residual toner cleaning device (17) ) has been installed.

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

An opening (7a) is formed in the shield plate of the secondary Sufrotron charger (7), and a red cut filter (5)
faces the aperture (78), and the red filter (6) is installed adjacent to the shield plate.The light image from the image exposure device 20) described below passes through the filters (5) and 9 (6) at the same time. The light that has passed through the red cut filter (5) reaches the surface of the drum (1) together with the corona discharge of the secondary scorotron charge (7).

The LED array (8) includes a plurality of light emitting diodes (LEDs).
) are arranged in parallel in the width direction of the drum (1), and each light emitting diode lights up to irradiate a designated area with light. The designated area is a characteristic main part of the present invention, and for example, as in the designated area (X) shown in FIG.
) is converted into a red copy image part (R) in the copy image (S, ), and the other image part, that is, the red image part (R1) is converted into a red copy image part (R1). ) refers to the area to be copied.

In addition, the black image area (BLI゛) and red image area (R1') other than the specified area (X) of the original image (S,) are directly transferred to the black copy image area (BLt') and the red copy image area (
R1'). The blinking of the LED array (8) is controlled by a signal from an image area designation means consisting of a switch on the operation panel (not shown) of the copying machine body, and in the width direction (Y), the lighting of individual light emitting diodes,
When the light is turned off, the image forming direction (Y,) is determined by controlling the lighting time of each light emitting diode.

The image exposure device (20) employs a well-known slit exposure method with a moving optical system, and includes an exposure lamp (21), mirrors (22), (23), (24), and a projection lens (25).

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

On the other hand, the copy paper is stored in the automatic paper feed force cera) (30), is fed one by one from the top paper by the paper feed roller (31), and is fed by the timing roller pair (32) in the manner described in detail below. The image is conveyed between the drum (1) and the transfer charger (15) in synchronization 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 material such as 0 μm acrylic or polyethylene terephthalate, photoconductor layer (II) has a thickness of 50 to 100 μm.
It consists of m selenium arsenic (A□S, 1). If acrylic is used, it is attached by dipping or spraying, and polyethylene terephthalate is also attached by the same method, or by covering the selenium deposition drum with a heat shrink type. The rotational peripheral speed of drum (1) is 130 mm/sec
It is.

In addition, the primary scorotron charger (3) has the ability to charge the surface of the drum (1) to -1500 to 2000V, and the secondary scorotron charger (7)
A positive polarity corona discharge is performed, and the first scorotron
Drum (1) negatively charged by charger (3)
It has the ability to eliminate the surface potential of approximately OV. The tertiary scorotron charger (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 Red Conversion Mode] This copy mode is a copy mode achieved for the first time by the present invention, and the black image portion within the designated area is converted to a chromatic color (red in this embodiment) to produce a copy image.

First, the eraser lamp (
2), and at the same time, a negative corona discharge is performed by the first suflotron charge-v(3). With this, as shown in (A) in Figure 3,
The surface of the dielectric layer (I) is charged to 12,000 V, and positive charges are induced between the dielectric layer (I) and the photoconductor layer (1).

Next, positive polarity corona discharge is performed by the second scorotron charge (7), and red cut image exposure is performed by the exposure device (2o) via the red cut filter (5). In this way, as shown in FIG. 3 (B), the surface of the dielectric WI (I) is neutralized to almost ov, and only the white part (background part) of the original is exposed to light, which corresponds to the white part. The surface charge of the dielectric layer (I) is neutralized, and the surface charge of the photoconductor layer (I) is neutralized.
The positive charge of II) also leaks through the conductor support ff(III). A dielectric layer (I) and a photoconductor m<n corresponding to a black image area and a red image area that are not exposed to light.
A charge is retained between the

Next, a red image exposure is performed through a red filter (6). With this, as shown in FIG. 3 (C), the red image area of the original is exposed, and the dielectric material,
The positive charges held between the photoconductor WI (II) and the photoconductor WI (II) are removed by the dielectric layer (I) due to the decrease in the electrical resistance of the photoconductor layer (It). Conductor support H! except for those constrained by the surface charge of H! I (■)
leaked via. 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 portion here is -300 to 400V.

Next, when a portion corresponding to the designated area passes by a signal from the image area designating means, the LED array (8) is partially illuminated. With this, as shown in FIG. The charges leak through the conductor support WI (III), except those bound to the surface charge of the dielectric layer (1), due to the decrease in the electrical resistance of the photoconductor layer (II). As a result, the surface potential corresponding to the black image portion in the designated area A, which did not increase to the negative side in the above step, increases to the negative side.

That is, by passing through the designated area exposure step using the LED array (8), the electric charge of the portion corresponding to the black image portion in the designated area becomes the same as the electric charge of the portion corresponding to the red image portion.

Therefore, regular development is performed by a developing device (10) using a developer containing positively triboelectrically charged red toner. As a result, as shown in FIG. 3(E), the red toner (Tr) adheres to the black image portion within the designated area as well as the red image portion.

Next, a positive corona discharge is performed by the tertiary scorotron charger (11). As a result, as shown in FIG. 3(F), the surface potential of the red toner-attached portion is reduced to approximately 0.

Subsequently, the entire surface is exposed using an eraser lamp (12). With this, as shown in FIG. 3 (G), the positive polarity of the part corresponding to the black image area other than the designated area held between the dielectric layer (I) and the photoconductor layer (If) The charges leak through the conductor support layer (III), except those bound by the surface charge of the dielectric layer (I), due to the decrease in the electrical resistance of the photoconductor layer (II). . As a result, the surface potential corresponding to the black image area other than the designated area, which did not increase to the negative side in the previous process, increases to the negative side. The surface potential of the black image part here is -400~5
It is oov.

Therefore, regular development is performed by a developing device (14) using a developer containing positively triboelectrically charged black toner. As a result, black toner (Tb) adheres to the black image portion other than the designated area, as shown in FIG. 3 (H).

Through the above copying process, it is possible to convert only the black image portion within the specified area to red, and 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 LED array (D) shown in FIG.
Only the designated area exposure step 8) is omitted, and the other steps are the same as in the designated area red conversion mode.

[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 Print Mode] This copy mode is for erasing the black image portion of the original and copying only the red image portion 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 opposite to the black cut mode,
This mode erases the red image portion of the original and copies only the black image portion 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 m).Furthermore, the photoconductor! When a low resistance material such as CdS is used as (II), an eraser lamp (2
) is not necessary.

As is clear from the above explanation, the present invention has a transparent dielectric layer,
Using an electrostatic latent image carrier consisting of a photoconductor layer and a conductor support layer, image exposure is performed through a chromatic complementary color filter or a chromatic color filter, and it is possible to partially transmit light through a white or chromatic filter that can emit light. The light emitting means is made to partially emit light at the same time as the chromatic image exposure process or immediately after the chromatic image exposure process based on the signal from the image area specifying means, and the specified image area is irradiated with light. The electric charge in the area corresponding to the black image area is the same as the electric charge in the area corresponding to the chromatic image area, and the black latent image area in such a designated area is converted to chromatic toner in the next chromatic color development process. It is developed together with the chromatic latent image portion, and it is possible to obtain a copy image in which the black image portion of the original is arbitrarily and partially converted into chromatic color, which was previously impossible. Of course, as explained in the example above,
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, (I[)...Photoconductor layer, (
III)...Conductor support layer, (1)...Electrostatic latent image carrier drum, (2)...Eraser lamp, (3)...
1st order Sufrotron charger, (5)...Red cut filter, (6)...Red filter, (7)...
・Second Scorotron Charger, (8)...LE
D array, (10)... red developing device, (11)...
...Third Sufrotron Charger, (12)...
Eraser lamp, (14)...Black developing device, (2
0)...Image exposure device. Figure 4

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. A color image forming method, wherein a light emitting means for emitting light that can partially emit white or that can pass through a chromatic color filter is activated simultaneously with or immediately after the chromatic image exposure step according to a signal from an image area specifying means. A two-color image forming method characterized by comprising a designated area exposure step of emitting light partially and applying light to a designated image area.