JPS6398672A - 2-color image forming method - Google Patents

Abstract

PURPOSE:To form 2-color images corresponding one to one to the images of an original and to permit selection of plural chromatic colors by advancing a pair of a chromatic complementary color filter and chromatic color filter corresponding to the selected chromatic colors into an optical path for image exposing and developing the images with developers contg. the toners of the selected chromatic colors in a chromatic color developing stage. CONSTITUTION:Corona discharge of a negative polarity by a scorotron charger 3 for electric charge is executed simultaneously with full-surface exposuring (A). Corona discharge by a scorotron charger 4 for 1st destaticization and the image exposing to cut a red color through a cyan filter are executed (B). Red image exposing through a red filter is then executed (C) and development by the developer contg. the red toner triboelectrostatically charged to a positive polarity by a 1st chromatic color developing device (D) and the corona discharge of the positive polarity by a scorotron charger 9 for 2nd destaticization are executed (E). Full-surface exposing is then executed (F) and the development with the developer contg. the black toner triboelectrostatically charged to the positive polarity by a black developing device is executed (G). The 2-color copied images corresponding one to one to the images of the original consisting of the black and red colors are thereby obtd. with just one time of image exposing stage.

Description

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

Conventionally, as a method for obtaining a two-color copy image corresponding to an original image composed of two colors, black and chromatic colors, the
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 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.

However, with this method, only black and one specific chromatic color can be reproduced, and multiple chromatic colors can be selectively reproduced. The problem is that it is not possible to distinguish and reproduce each color.

On the other hand, various full-color image forming methods have been proposed, but these involve multiple transfer steps using yellow, magenta, and cyan toners, resulting in larger equipment and slower copying speeds. In addition, black color has a problem of poor reproducibility because it is reproduced by overlapping toners.

Therefore, the two-color image forming method according to the present invention provides (a) a means for determining the intermediate point uniformly on the surface of an electrostatic latent image carrier consisting of a transparent dielectric layer, a photoconductor layer, and a conductive support layer; a charging step in which the surface of the electrostatic latent image carrier that has passed through this charging step is neutralized; and a chromatic cut image in which image exposure is performed through a chromatic complementary color filter at the same time as the first static eliminating step. an exposure step, a chromatic image exposure step in which the image is exposed through a chromatic filter, a chromatic development step in which the image is developed with chromatic toner, and static electricity is removed from the surface of the electrostatic latent image carrier that has undergone this chromatic development step. Second
comprising a static elimination step, an entire surface exposure step in which the surface of the electrostatic latent image carrier that has undergone the second static elimination step is uniformly irradiated with light, and a black development step in which development is performed with black toner; A pair of a chromatic complementary color filter and a tangible color filter for the selected chromatic color is introduced into the image exposure optical path, and (C) in the chromatic color development step, the image is developed with a developer containing a toner of the selected chromatic color. Features.

In the above method, first, a specific chromatic color used in the original is selected, and a pair of a chromatic complementary filter and a chromatic filter for the selected chromatic color is placed in the image exposure optical path. enter in. Further, the operation of the developing device is switched or the developing device itself is replaced so that development can be performed using a developer containing the selected chromatic toner. Then, by going through the charging step, the first charge removal/chromatic color cut image exposure step, and the chromatic image exposure step, a latent image corresponding to the chromatic image portion of the original is formed on the surface of the electrostatic latent image carrier. is formed into a chromatic toner image in a chromatic developing process. Subsequently, by going through a second static elimination step and an entire surface exposure step, a latent image corresponding to the black image area of the document is formed on the surface of the static latent image carrier, and this is formed into a black toner image in a black developing step. .

In this way, a two-color image that corresponds one-to-one to the original image containing a specific chromatic color is formed, and a plurality of chromatic colors can be selected.

Embodiments of the two-color image forming method according to the present invention will be described below with reference to the accompanying drawings. In each of the following embodiments, red, blue, and green, which are the most frequently used chromatic colors, will be explained as examples.

[First Embodiment] FIG. 1 shows the overall structure of an electrophotographic copying machine used in a first embodiment of the present invention, in which a drum (1 ) is installed so that it can be rotated in the direction of arrow (a). As shown in FIG. 2, the electrostatic latent image carrier has a transparent dielectric layer (I) on the surface and a photoconductor layer (I) in the middle.
If) is provided, the conductor support layer is based on II (III), and the conductor support layer (I[[) is grounded. Specifically, the dielectric layer (I) is made of an insulating transparent material such as acrylic or polyethylene terephthalate with a thickness of 10 to 20 μm, and the photoconductor Jli (I[) is made of selenium arsenic (As*S) with a thickness of 50 to 100 μm. , m).

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.

Around this drum (1), eraser lamps <
2) , IT sousflotron charger (3), 1st
Sufrotron charger for static elimination (4), magnetic brush type first colored developing device (7a) containing developer containing chromatic toner, second colored developing device (7b), second Scorotron charger for static eliminating (9), eraser lamp for full-surface exposure (10), magnetic brush type black developing device (11) containing developer containing black toner, transfer charger (
15), a separation charge w (16), and a blade type residual toner cleaning device (17) are installed.

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 (2g).

On the other hand, copy paper is stored in an automatic paper feed cassette (30), is fed one by one from the top layer by a paper feed roller (31), and is fed to a drum by a pair of timing rollers (32) as described in detail below. 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).

By the way, the eraser lamp (2) is used to erase the residual charge on the surface of the drum (1) at the final stage of the copying operation, but at the start of the copying operation, the shield of the charging scorotron charge (3) The inside of the board is also exposed.

Further, in this embodiment, the charging scorotron charger (3) performs negative polarity corona discharge, and the neutralizing scorotron charge-v (4), (9) performs positive polarity corona discharge.

The chromatic complementary color filter (5) and the chromatic color filter (6) are:
A cyan filter (5C) that cuts out specific chromatic colors, in this example, a red filter (6R), and a yellow filter (5Y) that cuts out blue.

A blue filter (6B), a magenta filter (5M) that cuts green, and a green filter (6G) are attached to the support rod (5
1>.

(61) are fixed at regular intervals point-symmetrically on the outer periphery of the image exposure device (20), and are located at the end of the optical path of the image exposure device (20). As shown in Fig. 3, the pulleys (52) and (62) fixed to each support rod (51) and (61) are connected by a belt (63) and fixed to the end of the support rod (61). The stepped gear (64) is the output gear (65) of the stepping motor (65).
66) are engaged. Therefore, the stepping motor (
65) by 180° in the direction of arrow (b), filters (5) and (6) rotate in synchronization in the direction of arrow (c), and each filter (5C), (5M), (5
Y), (6R), (6G), and (6B) enter the exposure optical path in pairs with a chromatic color and its complementary color. In this way, when entering the exposure optical path, each of the complementary color filters (5) faces the shield plate opening (4a) of the first static elimination Sufrotron charger (4), and each of the chromatic color filters (6) faces the shield plate opening (4a). The light image from the zero image exposure device (2o) located adjacent to the filter (5),
(6) and the complementary color filter (5), the light reaches the surface of the drum (1) along with the corona discharge of the first static elimination Suflotron charger (4).

The first chromatic color developing device (78) and the second chromatic color developing device (78)
b) can accommodate, for example, a developer containing red toner and a developer containing green toner, and is removable at a predetermined position. Additionally, a third chromatic color developing device e (not shown) containing a developer containing blue toner is separately prepared.
It can be replaced with the developing device (7a) or (7b). Sensors are set at these two developing positions to read the color of the attached developing device, and the color signals are input to a microcomputer (CPU) as shown in FIG.

On the other hand, the selection of the chromatic color to be copied is performed using the selection keys (70), (72), (7) on the color selection panel shown in FIG.
This is done by pressing 4). When the color selection keys (70), (72), and (74) are pressed, the corresponding switches are turned on, input is made to the microcomputer (CPU), and the corresponding display L E D (7
1), (73).

(75) is turned on, and the driver circuit of the stepping motor (65) operates to drive the motor (65) to set the filters (5) and (6) to the selected chromatic color pair. Switch. At the same time, the exposure lamp voltage control circuit operates to switch the voltage applied to the exposure lamp (21). Note that control of the exposure lamp voltage will be explained later. Further, the developing clutch of the developing device (7a) or (7b) containing the selected chromatic color toner is turned on, and the developing device (7a) or (7b) of the selected chromatic color is turned on.
7b) so that it operates.

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

Here, a case will be described in which a document drawn in black and red is used and red is selected as the chromatic color. Therefore, the cyan filter (5C) is used as the complementary color filter (5).
, the chromatic filter (6) is a red filter (6R)
enter into the exposure optical path in pairs (see Figure 1), and the first chromatic color developing device (7a) containing the developer containing red toner is turned on, and the second chromatic color developing device (7a) is turned on. The developing device (7b) is turned off.

First, the eraser lamp (
2), and at the same time, a negative polarity corona discharge is performed by the charging Suflotron charger (3). As shown in FIG. 6 (A), the surface of the dielectric W (I) is negatively charged, and the gap between the dielectric layer (I) and the photoconductor layer (n) is A positive charge is induced in the

Next, positive polarity corona discharge is performed by the first static elimination Sufrotron charger (4), and red cut image exposure is performed by the exposure device (20) via the cyan filter (5C). As shown in (B) in the figure, the surface of the dielectric layer (I) is neutralized to approximately Ov, and only the white part (background part) of the document is exposed, and the dielectric layer (I) corresponding to the white part is exposed to light. ) is neutralized and the surface charge of the photoconductor layer (I
The positive charge of I) also leaks through the conductor support layer (I[[). A dielectric material Ji3 (I) and a photoconductor layer (It
) and a charge remains between them. That is, the photoconductor layer (I) that is not exposed to light maintains a high resistance, and the surface potential is removed to approximately Ov by corona discharge, and the dielectric layer (I) appears to have a high resistance.
The surface of the conductor support layer (II) is short-circuited. This allows the dielectric J'fi! (I) Negative charges on the surface are distributed in parallel to the ratio of the capacitance (CI) of the dielectric layer (I) to the capacitance (C1) of the photoconductor layer (If).

Next, red image exposure is performed through a red filter (6R). In this way, as shown in FIG. 6 (C), the red image area of the original is exposed and the red image area that was held between the dielectric layer (I) and the photoconductor layer (It) in the previous process is exposed. The positive charges in the area corresponding to the red image area decrease in electrical resistance of the photoconductor layer (I[), so that the positive charges in the area corresponding to the red image area are reduced by the conductor support layer, except for those that are restricted by the surface charges of the dielectric layer (I). (I[). As a result, the surface potential of the drum (1) corresponding to the red image area increases to the negative side.

Next, development is performed by a first chromatic color developing device (7a) using a developer containing positively triboelectrically charged red toner. As a result, red toner (Tr) adheres to the red image portion, as shown in FIG. 6(D).

Next, corona discharge of positive polarity is performed by the second static elimination Sufrotron charger (9). As a result, as shown in FIG. 6(E), the surface potential of the red toner-attached portion is reduced to approximately OV.

Subsequently, the entire surface is exposed using the eraser lamp (10) for whole surface exposure. With this, as shown in (F) in FIG. 6, the positive charge in the portion corresponding to the black image area that had been retained between the dielectric layer (I) and the photoconductor layer (II) is now The reduction in the electrical resistance of the photoconductor layer (I[) allows leakage through the conductor support layer (I), except for those bound by the surface charge of the dielectric layer (I). As a result, the surface potential corresponding to the black image area, which did not increase to the negative side in the previous red image exposure process, increases to the negative side.

Therefore, development is performed by a black developing device (11) using a developer containing positively triboelectrically charged black toner. As a result, black toner ('Ib) adheres to the black image portion, as shown in FIG. 6 (G).

Through the copying process described above, a two-color copy image that corresponds one-to-one to the original image consisting of black and red can be obtained through a single image exposure process.

Note that when the operator selects red as in this embodiment, the first developing device containing the developer containing red toner is
．． There may be cases where the second developing position is not fully installed.

In such a case, the corresponding display LED (71) is flashed to prohibit the copying operation, or one of the chromatic color developing devices is operated to perform development in a color different from the selected chromatic color. be done. Therefore, by actively using this control, it is possible to obtain a two-color image in which the chromatic colors of the original are converted into other chromatic colors.

Also, if both the first chromatic color developing device (7a) and the second chromatic color developing device (7b) are turned off, all image areas can be copied in black, and if the black developing device (11) is turned off, It is also possible to obtain a copy image of only the chromatic image portion by turning off the second static elimination Suflotron charger (9) and the eraser lamp (10).

By the way, in this embodiment, the voltage applied to the exposure lamp (21) can be changed depending on the selected chromatic color, and the exposure light amount is controlled to be switched to the optimum value for each chromatic color. That is, each selected chromatic color has a different wavelength, the spectral sensitivity characteristics of the electrostatic latent image carrier and the efficiency of each filter are different, and the exposure lamp (21) itself has a specific emission wavelength. Depending on the light intensity of the exposure lamp (21), the surface potential of the electrostatic latent image chromatic image area may decrease (the chromatic image density may decrease).
, induction of black image areas, and toner fogging on white areas (background areas). According to experiments conducted by the inventors, the induced potential in the white area (background area) and each chromatic image area changes with a peak as the amount of exposure light increases, and the induced potential in the black image area is approximately proportional to the amount of exposure light. . The induced potential of the chromatic image area peaks at an exposure light amount value where the induced potentials of the white area (background area) and the black image area are approximately equal. This peak value differs for each chromatic color. Therefore, in this embodiment, the exposure lamp (2
The amount of light in step 1) is switched to a value that indicates the peak of the induced potential in each chromatic image area. In addition, an exposure lamp (21
), the contrast between the chromatic image area, the black image area, and the white area (background area) can be changed by appropriately changing the exposure amount during chromatic color cutting and the exposure amount during chromatic color transmission. was confirmed.

Next, referring to FIGS. 7 and 8, filter (5).

A modification of the switching structure (6) will be explained.

This is arranged by arranging a specific chromatic color filter and its complementary color filter in pairs on support members (55), (55), and moving rail portions (56) of the support members (55), (55),
(56) is slidably attached to the guide rails (58) and (5B), and the rack (56) is attached to the left support member (55).
57) to the output pinion (
66) are meshed together. The combinations of paired filters are the same as shown in Figure 3: a cyan filter (5C) and a red filter (6R) for red, and a yellow filter (5M) and a green filter (6G) for green.
), a yellow filter (5Y) and a blue filter (6B) for blue. Therefore, the stepping motor (6
5) rotates forward and backward, the entire filter moves left and right, and the selected chromatic color pairs of filters (5C) and (6R), (5M) and (6G), and (5Y) and (6B) are formed. enter into the exposure optical path.

[Second Embodiment] FIG. 9 shows the main parts of an electrophotographic copying machine used in a second embodiment of the present invention. In this copying machine, a first chromatic color developing device (7a) for red development is provided. In addition to the second chromatic color developing device (7b) for green development, a third chromatic color developing device (7c) containing a developer containing blue toner for blue color development is provided.
) is added, and the other configuration is the same as that shown in Fig. 1 above, and the switching structure of filters (5) and (6) can also be the same as that shown in Figs. 7 and 8. It is.

Therefore, in this embodiment, there is no need to replace the chromatic color developing device each time, and the developing device (
Any one of 7a), (7b), and (7c) is selectively operated. The copying process is as shown in FIG.

[Third Embodiment] Figure 10 shows the main parts of an electrophotographic copying machine used in the second embodiment of the present invention. The filter is attached to the chromatic color development position and can be detached from the chromatic color development position.The chromatic complementary color filter is attached to the first charger (4)
The chromatic filter is positioned adjacent to the shield plate, facing the shield plate opening (4a). In FIG. 10, a developing device (7c) containing a developer containing red toner is shown.
is fully installed, and a cyan filter (5C) and a red filter (6R) are attached to this developing device (7a). Note that the other configurations are similar to those shown in FIG. Therefore, in this embodiment, the copying process is as shown in FIG. 6, in which the chromatic color developing device is replaced according to the chromatic color of the original and then the copying is performed.

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 machine, in addition to the configurations shown in FIGS.
4), instead of (9), use a normal corona discharge charger, or use a charger for static elimination (4).
>, An alternating current voltage may be applied to (9).

On the other hand, when a low-resistance material such as CdS is used as the photoconductor layer (IF), it is not necessary to expose the entire surface to light using the eraser lamp (2) during charging in (3).

As is clear from the above explanation, the present invention includes a transparent dielectric layer,
An electrostatic latent image carrier consisting of a photoconductor layer and a conductive support layer is used, and image exposure is first performed through a selected chromatic complementary color filter and a chromatic filter, so that the surface of the electrostatic latent image carrier is A latent image corresponding to the chromatic image area of the document is formed, and this is formed as a toner image of the selected chromatic color in a chromatic color development step, followed by a second static elimination step and an entire surface exposure step. As a result, a latent image corresponding to the black image area of the original is formed on the surface of the electrostatic latent image carrier, and this can be formed as a black toner image in the black developing process. Copy images of two colors corresponding to each other can be obtained by simply going through a single image exposure step and a transfer step, and a plurality of chromatic colors can be selected.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an electrophotographic copying machine used in a first embodiment of the present invention, FIG. 2 is a sectional view of an electrostatic latent image carrier, and FIG.
The figure is a perspective view of the filter switching structure, Figure 4 is a plan view of the operation panel, Figure 5 is a block diagram of the control circuit, Figure 6 is an explanatory diagram of the copying process, and Figures 7 and 8 are the filter switching structure. It is a perspective view and a front view which show another example. FIG. 9 is a block diagram of the main parts of the copying machine used in the second embodiment, and FIG. 10 is a block diagram of the main parts of the copying machine that can be used in the third embodiment. (I)...Dielectric layer, (I)...Photoconductor layer, (I
[)... Conductor support layer, (1)... Electrostatic latent image carrier drum, (2)... Eraser lamp, (3)... Sufrotron charger for charging, (5), (5C ),
(5Y), (5M)...Chromatic complementary color filter, (6
), (6R), (6B), (6G)...Chromatic filter, (7a>, (7b), (7c)"・Chromatic color developing device, (9) ---Second static elimination Suflotron・
Charge ~, (10)... Eraser lamp for full surface exposure, (11)... Black developing device, (20)... Image exposure device, (21)... Exposure lamp.

Claims (1)

[Scope of Claims] 1. A charging process for uniformly charging the surface of an electrostatic latent image carrier consisting of a transparent dielectric layer, a photoconductor layer, and a conductive support layer, and the electrostatic charge generated through this charging process. The first step is to remove static electricity from the surface of the latent image carrier.
A static elimination step, a chromatic cut image exposure step in which image exposure is performed through a chromatic complementary color filter at the same time as this first static elimination step, a chromatic image exposure step in which image exposure is performed through a chromatic filter, and chromatic toner. A chromatic color development step in which the image is developed in a chromatic color developing step, a second charge removal step in which charge is removed from the surface of the electrostatic latent image carrier that has undergone this chromatic color development step, and a uniform charge removal step that is performed on the surface of the electrostatic latent image carrier that has undergone this second charge removal step. A full-surface exposure process that applies light irradiation,
A black developing step for developing with black toner, a pair of a chromatic complementary color filter and a chromatic filter for the selected chromatic color is introduced into the image exposure optical path, and the chromatic color developing step is for developing the selected chromatic color. A two-color image forming method comprising: developing with a developer containing toner. 2. The two-color image forming method according to claim 1, wherein the amount of exposure light from an exposure lamp for performing image exposure is switched depending on the selected chromatic color.