JPS6263951A - Multicolor electrophotographic copying device - Google Patents

Abstract

PURPOSE:To attain multicolor copying of a full-color copy or the like, black-and- white copying, erasing of a specific color on a bicolor original, reproducing of one optional color on the whole of a picture, etc. by providing two electrifiers different in charging condition above an exposure position in the peripheral moving direction of a photosensitive body. CONSTITUTION:Since the first segment 30a consists of a composite photosensitive body and the second segment 30b consists of a single photosensitive body, a red-omitted toner image and a black-omitted toner image are formed together on the first segment of the composite photosensitive body divisionally by two operations. If both of the first and second segments consist of composite photosensitive bodies, the red-omitted toner image and the black-omitted toner image are formed on segments different from each other; and since the full-color copy cannot be generated from a multicolor original by a photosensitive belt 30, it is preferable that interchangeable cartridge type photosensitive bodies and supporting rolls are used and are interchanged in accordance with purposes. Thus, originals are copied in various mode such as the full-color mode, the monochromatic color mode, the bicolor mode, and color erase mode.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a multicolor electrophotographic copying apparatus using a color separation image overlapping transfer method.

As a prior art multicolor electrophotographic copying apparatus, one employing a color separation image superimposition transfer system is well known. In this type of multicolor copying device, the three primary colors of light, blue,
Three color separation filters, green and red, are provided so that they can be switched and inserted, and the document is irradiated with a white light source, and each of the above color separation filters is switched and inserted into the optical path, and the photoreceptor is exposed three times. Each time, the latent image formed on the photoreceptor is sequentially placed downstream of the exposure position of the photoreceptor, and the blue, green,
The three colors are sequentially developed using one developer each containing yellow, magenta, and cyan developers, which are complementary colors to the three colors of red.
A color toner image is formed and transferred onto a transfer paper wound around a transfer drum that is placed in contact with the photoreceptor at a position downstream of each developing device, or is transferred onto a transfer paper that is placed in contact with the photoreceptor. After being superimposed and transferred onto a drum or endless belt-like intermediate transfer body, the images are transferred to transfer paper at once and fixed, thereby creating a color copy corresponding to the original.

In the case of variable magnification duplication of reduction or enlargement, the exposure optical system is an optical system capable of variable magnification, and exposure is performed by displacing a part of the lens and mirror.In the case of variable magnification duplication of monochrome It is similar to Now, the spectral transmittance characteristics of the above color separation filter and the spectral reflectance characteristics of each color toner are different from the ideal spectral characteristics, so by mixing these colors, pure black or dark areas of chromatic areas can be made into the same tone as the original. It is difficult to reproduce with contrast, and it is inefficient to copy a black and white original by mixing three color toners through three exposures. Therefore, in order to efficiently copy black-and-white originals and improve the contrast of color copies, a black developer is installed in addition to the three-color developer described above, and a color copying T is used that performs four exposures when making color copies. Devices are also known. In this method, when forming an image for black development, an ND filter or a yellow filter is used as a filter. During black and white copying, the formed latent image is developed with a black developing device in one exposure to create a black and white copy.

In the above-mentioned multicolor copying device equipped with four-color developing units of yellow, cyan, magenta, and black, a pantochromic single-layer photoreceptor similar to that of a normal black-and-white copying device is used as a photoreceptor, and a filter is used. By changing the color of the photoreceptor, the latent image formed on the photoreceptor is changed, thereby making full-color copying and single-color copying of the entire image of the original possible.

By the way, documents used in offices, such as administrative documents and technical reports, have red or blue lines or writing mixed in with black text or diagrams, or areas that should call attention. Sentences, etc. are often written in different colors. When making copies from such two-color (for example, black and red) originals, it is possible to copy in each mode depending on the purpose: a) all-black mode, red mode, c) all-red mode, d) black-out mode, e) red-black mode. is desirable.

A two-color electrophotographic copying apparatus for the purpose of copying a two-color original in all of these modes was previously filed by the present applicant in Japanese Patent Application No. 87511. This device is a specific two-color copying machine, and is suitable for each of the above-mentioned modes of copying, but cannot perform multi-color copying, including full-color copying such as copying paintings or color photographs.

Therefore, if it is possible to add the above-mentioned modes of copying functions from two-color originals to the multi-color copying device explained at the beginning,
The utility of the copying device is increased, and it is convenient that one copying device can function as two copying devices.

Purpose In view of the above, the present invention provides multicolor copying such as full-color copying, black-and-white copying, erasure of specific colors of two-color originals,
It is an object of the present invention to provide a multicolor copying apparatus capable of reproducing an entire image in any one color.

Structure In order to achieve the above-mentioned object, the present invention sequentially exposes the color-separated optical image of the original on a rotating photoreceptor, and each time the latent images formed on the photoreceptor are different from each other. In an electrophotographic copying apparatus capable of creating a multicolor copy by sequentially developing one color at a time using a developing device that holds color developers and transferring them onto the same transfer paper in an overlapping manner, at least the photoreceptor described above is used. ] The image component is formed as a composite photoreceptor made by laminating at least two photoconductive layers with different spectral sensitivities on a conductive substrate, and charging conditions are applied to the upstream side of the exposure position in the circumferential direction of the photoreceptor. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1(,) is a diagram showing an embodiment of the photoreceptor used in the multicolor electrophotographic copying apparatus of the present invention, in which the photoreceptor 30
The first segment 30 is formed in the shape of an endless belt and has a circumference equal to or more than two of the largest image forming area (hereinafter referred to as a segment) created by this copying apparatus. As shown in FIG. 1(b), the second segment a and the second segment 30b are formed with an appropriate width spaced apart from each other. As shown in FIG. 1(C), the endless belt-shaped photoreceptor 30 has a ground layer 30--3 made of aluminum foil laminated on a base i, 30 = 4, such as a polyester film, and a ground layer 30--3 made of aluminum foil, etc. consists of a photosensitive layer laminated thereon. Figure (c) shows a cross section of the first segment 30a,
The photosensitive layer is a first layer (U layer) 30- with mutually different spectral sensitivities.
1 and a second layer (L layer) 30-2 are stacked. Second
In this example, segment) and 3'Ob are a single layer of a panchromatic photosensitive layer similar to a normal black-and-white copying device.

FIG. 2 is a diagram showing an embodiment of a multicolor copying apparatus using the endless belt-shaped photoreceptor 3o described above.

An original placed on a contact glass 2 provided on the top plate of the copying machine body 1 is illuminated by an exposure lamp 4, and the reflected light is reflected by a first mirror 5, a second mirror 6,
An image is formed on a photoreceptor bell 30 by an exposure optical system consisting of a third mirror 7, an imaging lens 8, and a fourth mirror 9. The exposure lamp 4 and the first mirror 5 move together at a constant speed parallel to the original, and the second and third mirrors 6 and 7 move together at a constant speed of V2.
The photoreceptor belt 30 moves in the same direction at a speed of Ru. In the middle of the exposure path, the three primary colors of light, blue, green,
Three red color separation filters 1'B and -11G.

1.1R and ND filters IN are switched so that they can be inserted into the optical path. Each time, the color separation filters 13B + llc + llR+ and IIN are switched and inserted into the light exposure mode, and the color-separated light image of one document is sequentially exposed onto the photoreceptor belt 30, and four different latent images are sequentially placed on the photoreceptor. Form.

Around the photoreceptor belt 30, following the exposure position, there is a developing device 3]1 having developers containing toners of four colors, yellow, magenta, cyan, and black, which are the three primary colors of the subtractive color method.
32. +33134 are arranged sequentially, and blue, green, and red filters IIB *1. IG! The latent images formed by the light beams that passed through the IIR are developed with yellow, magenta, and cyan developers, which are complementary colors to the filter colors, respectively, and the latent images formed by the light beams that passed through the ND filter] is developed with a black developer, and a toner image of the respective color is formed on the photoreceptor.

The toner images of each color are transferred to a transfer drum 15 provided in contact with the photoreceptor belt 30 at a position after the four developing devices at a paper feed section 1.
6, the leading edge is clamped by a clamper 18 provided on the transfer drum 5, and the images are transferred onto the transfer paper 17 wound around the transfer drum 15 in a superimposed manner by the action of the transfer charger 19. When the transfer of the four-color toner image is completed, the clamper 18 opens, and the transfer paper is separated from the transfer drum 15 by a separation claw of a separation charger 1 (not shown), sent to a fixing device 20, where it is fixed, and then transferred to a paper discharge tray 21.
A copy corresponding to the original is created.

When making a black-and-white copy from a black-and-white original or a multicolor original, insert an ND filter IIN in the exposure path and
A black-and-white copy is created by developing the latent image formed on the paper in black, transferring it to transfer paper 17, and fixing it.

When performing a variable magnification copy, the lens 8 and the second and third mirrors 6.7 are displaced by a predetermined amount according to the magnification m, and the scanner is moved at a speed inversely proportional to the magnification m, thereby making a copy at the required magnification. Made.

A primary charger 35', a secondary charger 35, and an eraser 36 are provided along the photoconductor 30 on the upstream side of the exposure section, and a cleaning device 37 and a static elimination charger 38 are provided on the downstream side of the transfer section. There is. Further, a surface electrometer 100 is provided between the exposure position and the development station. A cleaning device 37' is also provided downstream of the transfer paper separation position of the transfer drum 5.

Since this device is constructed as described above, as described above, each time it is charged using only the primary charging charger 35', it can be charged similarly to the conventional multicolor electrophotographic copying device of the color separation image overlapping transfer method. Needless to say, it is possible to make full-color copies and black-and-white copies, but the apparatus of the present invention further includes a charger for primary 35' and secondary 35'.
By dividing the photoreceptor into two parts (5) and reversing their charging polarities, it is possible to erase a specific color in one segment of the composite photoreceptor.

A primary that can charge the photoreceptor with different charging polarities,
Until now, various proposals have been made regarding technology for erasing specific colors in two-color originals using a secondary charger and a composite photoreceptor made of laminated photosensitive layers with different spectral sensitivities. This method is known per se, so a detailed explanation will be omitted, but this makes it possible to copy a two-color original in the five modes described above.

Below, an example of the process and change in the photoreceptor surface potential when copying a black and red two-color original in various modes will be explained with reference to the drawings. The composite photoreceptor used in this case is a photoreceptor that is insensitive to blue light.

(a) All black (monochrome) mode (see Figure 4 (a)) 1
Next: Using the charger 35', charge the photoreceptor at -100O
By charging the image to V and exposing the original image without inserting a filter, the charge is erased only on the white background. By developing this with a black developing device 34, an all-black copy can be obtained.

(b) Red out mode (see Fig. 4(b)) Same as the all black mode described above, the photoreceptor is charged to -1000 V using the charger 35', and the red filter IIR'i is
By inserting the photoreceptor and increasing the exposure amount, the photoreceptor is exposed for the red part in the same way as for the white part, the charge is erased, and a latent image of only the black part is formed. By developing this with a black developing device, a red-cut copy can be obtained.

(c) All red (white red) mode (see Figure 4 (C)) 1
The photoconductor is charged to +900V by the secondary charger 35', and then charged (-) by the secondary charger 35 so that the potential of the latent image on the photoconductor becomes about 1500V. After that, if exposure is performed without inserting a filter, the black and red areas will remain at 1500V, and the white background area will remain at approximately 0V.If all images are developed with the magenta developer 32, the entire image will remain. You will get a copy that is reproduced in magenta color. When copying a two-color original, unlike full-color copying, color reproducibility is not an issue; any color may be used as long as it is clearly different from black.

(d) Blackout mode (see Figure 4 (d)) The photoconductor is primarily charged to +1400V by the primary charger 35', then charged (=) by the secondary charger 35, and the latent on the photoconductor is charged. The image potential is set near zero V. After that, when exposure is performed, only the red part potential becomes about 1500V, and by developing this with a magenta developer, a black mode copy can be obtained. The behavior of the three loads above is expressed as the fifth
The steps are shown in Figures (a), (b), and (c).

Figure 5(a) shows the state of one charge in each layer when it is primarily charged to (+), and Figure 5(b) shows the state when it is secondarily charged to (-). (c) shows the state at the time of exposure.

As shown in this figure, only the red portion becomes a (-) potential due to exposure and is developed with toner having a (+) potential.

Ce) Red-black mode The black toner image and the magenta toner image obtained in the red-out mode and the black-out mode described above are superimposed on the transfer paper wound around the transfer drum 15 and transferred, thereby creating a document. A similar red-black (in this case red is reproduced as magenta) copy is obtained.

In the example of the photoreceptor belt 30 described in FIG. 1, the first segment is a composite photoreceptor and the second segment is a single photoreceptor, so both the red toner image and the black toner image are composite photoreceptors. The first segment, which is the body, is formed in two parts.

However, if both the first segment and the second segment are made of composite photoreceptors, the red toner image and the black toner image can be formed in separate segments, respectively. In this case, it is difficult to make full-color copies from multicolor originals using the photoreceptor belt, so it is better to use a cartridge system in which the photoreceptor and its support roller are replaceable, so that they can be replaced depending on the purpose. . By doing so, it becomes possible to copy in various modes including full color, monochrome color, two color, and achromatic. In this case, it is preferable to provide an indicator for copy mode selection on the operation panel.

(Endless Hell) The segments of the IBW photoconductor consist of two or more segments, and as mentioned above, (a) - 1000 is a single layer photoconductor and the other is a composite photoconductor ←] Both ″f: a composite photoconductor, and ( (c) For combinations of composite photoreceptors with different spectral sensitivities, such as the first segment being a blue-insensitive composite photoreceptor and the second segment being a red-insensitive composite photoreceptor) (a) + (b) or (a) The photoreceptor belt has three or more segments of the combination +(c).

It is also possible.

In the multicolor electrophotographic copying apparatus of the present invention, toner images formed multiple times on each segment or a certain segment of the photoreceptor belt are transferred in a superimposed manner, so accurate positioning of the images is essential.

The image alignment means -PA for this purpose will be explained next.

For example, an arbitrary black and white pattern is provided on the back surface of the contact glass 2, and is used as a recognition pattern to issue a signal at the start of exposure. Therefore, at the same time as the exposure starts (slightly in advance in terms of timing), the chargers 35' and 35 are manually operated, the above-mentioned recognition pattern is written on the photoreceptor 30, and the recognition pattern is read from a position at a predetermined distance from the pattern. Configure so that the original image begins. As mentioned above, a photoreceptor surface potential meter 10 is installed between the exposure position along the photoreceptor and the development station.
0 is provided, the recognition pattern written on the photoreceptor 30 is read by the electrometer 100, and a C (not shown) is provided.
Send a signal to the PU. The transfer drum J5, which rotates in synchronization with the scanner and the photoreceptor, is driven by a DC servo motor (not shown), but there is a lag in the timing between the signal from the recognition turn 7 and the transfer drum J5. If this occurs, the rotational speed of the DC servo motor is controlled by the CPU and the alignment is always performed at l- based on the recognition pattern generated in each segment.

FIG. 3 is a diagram showing another embodiment of the present invention.

Differences between this embodiment and the embodiment shown in FIG. The toner images thus produced are superimposed and transferred onto this intermediate transfer member 50, and a transfer sheet fed from the paper feed unit 16 is transferred between the transfer charger 51 provided opposite to the peripheral surface of the intermediate transfer member 50 and the intermediate transfer member 50. paper 17
The superimposed toner images are transferred at once, separated by a separation charger 52, conveyed to a fixing device 20 by a conveyor belt 53, fixed, and discharged to a paper discharge tray 21. . In this device, the toner image formed on the photoreceptor belt is transferred to the intermediate transfer member 50 and then to the transfer paper 17, so that the exposure optical system is 5th mirror 9 in the system
', and it is necessary to increase the number of mirrors by one. Due to this, the position of the color separation filter] has been moved slightly.

Other configurations and effects are the same as in the previous embodiment.

Effects As described above, according to the present invention, in addition to conventional full-color and monochrome color copying, it is possible to erase specific colors using a single multicolor electrophotographic copying apparatus, so that, for example, red and black two-color originals can be copied. Copies in all black, red-out, all-red, black-out, and red-black modes can be created as needed.

Furthermore, by adjusting the position and overlappingly transferring the image of another document onto the transfer drum or intermediate transfer body, it is possible to edit the image, and by combining the enlargement and reduction functions with the above-mentioned functions, special images can be created. Editing is also possible.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view showing an example of the photoreceptor used in the present invention, FIG. 1(b) is an open plan view of one room thereof, and FIG. 2 is a sectional view showing the overall configuration of an embodiment of the copying apparatus of the present invention, FIG. 3 is a sectional view showing the overall configuration of another embodiment of the invention, and FIG. 4(a)
(b), (C), and (d) are curve diagrams showing each step and changes in the photoreceptor surface potential when making copies in various modes from a two-color original using the apparatus of the present invention, and FIG. 5(a)
, (b) and (c) are schematic diagrams showing the behavior of charges on the composite photoreceptor at each step when making a black copy from a red-black original. 1... Multicolor electrophotographic copying device, 3... Manuscript, 5 to 9
... Exposure science, 11... Color separation filter, 15.
... Transfer drum, 17... Transfer paper, 30... Photoreceptor, 30a, 30b... Segment, 30-1, 30-
2... Photoconductive layer, 30-4... Conductive substrate, 31132*, 33+'34... Developer, 35, 3
5'...Electrical charger, whistle M I7 Day 4 Figure 4 (a) (b) All black mode Red blank mode (C)
(d) All red mode, black mode 1 pun, 1 item
Figure 5 (a) Primary charge (+) (b) Secondary charge (=) = (latent image potential zero port) (C)

Claims (3)

[Claims] (1) A color-separated light image of the original is sequentially exposed onto a rotating photoreceptor, and each latent image formed on the photoreceptor is developed one color at a time using a developing device that holds developers of different colors. In an electrophotographic copying device capable of producing a multicolor copy by sequentially developing and overlappingly transferring onto the same transfer paper, the above-mentioned photoreceptor is coated on a conductive substrate for at least one image segment. Two chargers that are formed as a composite photoconductor by laminating two photoconductive layers having different spectral sensitivities, and that can charge the photoconductor to opposite polarities on the upstream side of the exposure position in the circumferential direction of the photoconductor. An electrophotographic copying device characterized by being provided with. (2) The electrophotographic copying apparatus according to claim 1, wherein the photoreceptor is formed in the shape of an endless belt having a length of at least two image segments. (3) The above-mentioned photoreceptor has an image segment composed of two composite photoreceptors, and each image segment has a photosensitive layer having different spectral sensitivity.
The electrophotographic copying device described in Section 1.