JPH0562336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method, and more particularly to an image forming method and apparatus for forming color images using colored developers.

In recent years, office automation has been steadily progressing, and there has been a demand for communicating or filing higher density information. This information is most often communicated or stored as electrical or magnetic signals. Various means have been proposed or used to visualize electrical signals (or magnetic signals, etc.). An example of such a printer is an electrophotographic laser beam printer.

FIG. 1 is a schematic diagram of a laser beam printer, and in the figure, 1 is a signal light source such as a laser. The light beam generated from the laser light source 1 is transmitted to the scanner 2
The light passes through the lens 3 and scans on the photoreceptor 4. The photoreceptor 4, which has been previously charged by the charger 5, is discharged only in the portion irradiated with the light beam, and an electrostatic latent image is formed. The obtained latent image is visualized by the developing device 6 and becomes a toner image. This toner image is sent to a transfer section, transferred to a transfer material 8 by a transfer charger 7, and then fixed by a fixing device (not shown) to become a hard copy. On the other hand, photoreceptor 4
is irradiated by the discharge lamp 9 and further exposed to the cleaner 1
0 removes residual toner in preparation for the next copy cycle.

FIG. 2 shows a display device using a laser beam, and the same members as in FIG. 1 are given the same reference numerals. A toner image is formed on the photoreceptor 4 by going through the same steps as in the case of FIG. The toner image is sent to a display section having a transparent protective glass 11 and an illumination lamp 12 by rotation of pulleys P ₁ and P ₂ in the direction of the arrow, and is displayed there.

Although it is possible to obtain or display monochrome images in this manner, it is now desirable to go even further and to produce or display two-color or multi-color images.

FIG. 3 shows the schematic structure of a conventional color copying machine. In the figure, numerals 13, 14, and 15 are color developing devices, each having yellow, magenta, and cyan developers. When copying the original 16, for example, if the filter 17 is green, magenta, if the filter 17 is blue, yellow,
Filter 17 for cyan when red.
The latent images on the photoreceptor 4 are developed by contacting only the developer corresponding to the respective photoreceptors, and the latent images are transferred onto the transfer paper 8 in an overlapping manner. This is done by rotating the transfer paper three times along the transfer path 18 and superimposing each of the three colors yellow, magenta, and cyan on the photosensitive drum on the transfer paper so that there is no color shift. The transfer paper onto which the developed image has been transferred is sent to a fixing device 19, where the image is melted and fixed.

FIG. 4 shows a color information display device. Components that are the same as those shown in FIGS. 1-3 are provided with the same reference numerals. In the figure, a photosensitive drum 4 is irradiated with a modulated light beam from a laser light source 1 to form a latent image, which is developed by a yellow developer 13 and transferred onto a transfer roll 20 of one roll. Similarly, latent images corresponding to magenta and cyan are formed on the photosensitive drum 4, and the magenta developing device 14,
After being visualized by the cyan developer 15, the color is transferred to the transfer roll 20 so as to be superimposed on the previous color. The transfer roll 20 is rotated and sent to the display section, where the color image is displayed through the glass 11 illuminated by the illumination lamps 12.

However, in the display device shown in FIG. 4, the photosensitive drum and the transfer roll each have to be rotated three times in order to obtain an image, which takes time to display. Further, color misregistration is likely to occur when color images are superimposed on the transfer roll. Color toner that has been used once is
Because they are mixed together, they cannot be reused and must be disposed of, resulting in a waste of resources.

The purpose of the present invention is to solve the above-mentioned conventional drawbacks and
An object of the present invention is to provide an image forming method and apparatus that can obtain a pictorial color image with one exposure.

The present invention, which achieves the above object, is an image forming method in which a color image is formed by irradiating optical information onto a developer prepared by mixing a plurality of colored developers each having a different transmitting wavelength. Using a mixed developer that is a mixture of multiple colored developers that each have different transmission states and hold a specific polarity of charge,
The mixed developer is supported by a support, a potential difference is created between the mixed developer and the electrophotographic photoreceptor, and the two are opposed to each other, and a plurality of light beams having different wavelengths are emitted from the mixed developer side. The photoreceptor is irradiated, and the photoreceptor generates a charge of opposite polarity to the charge of the colored developer depending on the wavelength of the irradiated light beam, and the colored developer is selectively divided into colors according to the irradiated wavelength. A color image is formed by electrostatic adsorption to a photoreceptor.

Further, the color image forming apparatus of the present invention embodying the above method has a light transmission state that differs depending on the wavelength, holds charges of a specific polarity, and mixes colored developers of multiple colors in a thin layer. an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer, with the photosensitive layer side facing the developer on the transparent conductive substrate member; an optical means for irradiating a plurality of light beams with different wavelengths in the direction of the photosensitive layer;
a power source that generates a potential difference between the transparent conductive substrate member and the conductive substrate of the photoreceptor; A color image is formed by selectively electrostatically adsorbing colored developers to the photoreceptor according to the wavelength of the irradiation.

Embodiments of the present invention will be described below based on the drawings.

FIG. 5 shows the principle and configuration of the present invention. Three types of negatively charged translucent developers 22, blue (hereinafter also referred to as B), green (hereinafter also referred to as G), and red (hereinafter also referred to as R), are placed on the transparent conductive substrate 21 shown in the figure.
Coat it evenly in almost a single layer. This conductive substrate is made of Nesa glass or Mylar (trade name) coated with indium oxide. 23 is a photoreceptor having an N-type or bipolar photosensitive layer 23b provided on a conductive substrate 23a. For example, Greek G light is irradiated from the transparent conductive substrate 21 side at a position where the photoreceptor 23 is closest to the conductive substrate. The developer acts as a light filter before the green light reaches the photoreceptor. The green light passes through only the green developer and reaches the photoreceptor.

A DC bias is applied between the photoreceptor 23 and the transparent conductive substrate 21 by a power source 24 with the photoreceptor side being positive. When green light reaches the photoreceptor in this state, a photocarrier 25 is generated within the photoreceptor layer, leaving a positive photocharge near the surface of the photoreceptor, which attracts the negatively charged green developer onto the photoreceptor. . Blue and red developers do not adhere to the photoreceptor because they do not transmit green light. When blue light or red light is irradiated, the blue developer or red developer selectively adheres to the photoreceptor in the same manner as described above. In this way, a green, blue or red color image is formed on the photoreceptor.

However, since the direction of the applied DC bias is positive toward the photoreceptor, the negatively charged developer is subject to electrostatic force toward the photoreceptor even in areas that are not irradiated with light, which may cause background fog.
In order to prevent this background fog and obtain a better image, it is preferable to charge the surface of the photoreceptor negatively in advance as shown in FIG.

When the surface of the photoreceptor is negatively charged by the charger 26, the negatively charged developer 22 is electrically repelled by the surface of the photoreceptor. However, for example, at the position where the green light passes through the green developer and reaches the photoreceptor, the negative charge on the photoreceptor surface is discharged.
As described above, the negatively charged green developer adheres to the surface of the photoreceptor due to the action of the photo carrier 25. Similarly, when blue or red light is irradiated, blue or red developer adheres.

FIG. 7 is a schematic sectional view of a more specific example device. In the figure, 3 is a lens, 2 is a scanner,
27 is a half mirror, 28 is a developer coating device, 26 is a charger, 29 and 30 are power sources, 9 is a static elimination lamp, and 31 is a plurality of light beam sources each having a different wavelength. The developing device 28 may be of any type commonly used, but a developing device using a so-called two-component developer, which is a mixture of BGR mixed developer and iron powder, is optimal. Blue, green, and red developers are highly resistive colored particles that are triboelectrically charged. If this developer is positively triboelectrically charged, contrary to the above embodiment, the polarity of the power sources 29 and 30 is opposite to that shown in the figure, and the photosensitive layer used is a P-type or bipolar photosensitive layer. Use, charger 2
For No. 5, choose one that positively charges the surface of the photoreceptor.

A DC bias is applied between the developing device 28 and the transparent conductive substrate 21 with the transparent conductive substrate side being positive.
The BGR mixed developer that is negatively triboelectrically charged on the developing device can be coated almost uniformly on the transparent conductive substrate by adjusting the applied bias. The mixed developer is sent towards the photoreceptor,
A signal-modulated light beam is exposed from the transparent conductive substrate side at a position where the photoreceptor and the transparent conductive substrate are closest to each other, and an image is formed as described above. The light sources 31 are B.
Although the laser generates GR light, it may be an LED or other light source, or it may be a white light source with a color filter applied thereto to supply BGR light. Each light source independently participates in image writing. For example, if blue light and green light are generated simultaneously, both the blue developer and the green developer adhere to the photoreceptor, resulting in a mixed color. The formed image may be transferred to paper or the like as a hard copy as shown in FIGS. 1 and 3, or may be displayed as is as shown in FIGS. 2 and 4.

FIG. 8 and FIG. 9 show a display device using the present invention. In FIG. 8, reference numeral 11 designates a transparent protective portion such as glass, 12 a display illumination lamp, 32 a toner scattering prevention cover, and 33 and 34 cleaners. Other members that are the same as those in FIGS. 1 to 7 are given the same reference numerals. The photoreceptor is located in an image forming section 35 located close to the photoreceptor 23 and the transparent conductive substrate 21.
An image is formed, and after being neutralized by a static eliminating lamp 9 so as not to leave any optical history, it is sent to the display section by the rotation of pulleys P ₁ and P ₂ . After display, the photoreceptor is cleaned with a cleaner 33. The developer cleaned here is returned to the developer coating device 28 again. Further, the developer remaining on the transparent conductive substrate 21 after image formation is also cleaned by the cleaner 34, and the developer cleaned here is also returned to the developer coating device 28.

FIG. 9 is a cross-sectional view of an embodiment for displaying an image formed on a transparent conductive substrate 21. FIG. in this case,
To display an image, the light source 31 may be turned on in pulses, contrary to the case of FIG. 8 in which the image on the photoreceptor is displayed. For example, when displaying a red image, the green and blue light sources are turned on, and the red light source is not turned on. In this way, the green and blue developers adhere to the photoreceptor 23, and the red developer remains on the transparent conductive substrate 21, which is sent to the display section by the rotation of the pulley _P1 in the direction of the arrow. It will be done. In this case as well, the used developer is recovered to the developer carrier 28 by the cleaners 33, 34 and the developer scattering cover 32, and can be reused.

All of the developer used in the above embodiments is returned to the developer coating device. Therefore, the mixing ratio of the plurality of color developers does not change, and the developer is not consumed.

In the above embodiments of the present invention, full color display cannot be performed as in the color copy described above in FIG. 4, but pictorial color display consisting of a combination of at least three colors can be performed with one exposure. Obtainable. It is quite useful for obtaining information equivalent to normally used office documents.

FIG. 10 shows a schematic diagram of an apparatus for transferring a color image formed on a photoreceptor to a transfer material based on the principle shown in FIGS. 5 to 7. An image is formed on the photoreceptor 23 by the method described above.
The image on the photoreceptor is transferred onto a transfer paper 8 by a transfer charger 7. Thereafter, the transfer paper is sent to a fixing device 19, where the image is fixed. Although FIG. 10 shows an example in which an image on a photoreceptor is transferred, a configuration in which an image formed on a transparent conductive substrate 21 is transferred in a similar manner may also be used.

FIG. 11 shows an explanatory diagram of the principle and configuration of another embodiment of the present invention. In FIG. 11, 21 is a transparent conductive substrate, and 23 is a photoreceptor having a P-type or bipolar photosensitive layer 23b provided on a conductive substrate 23a. This transparent conductive substrate 21 is coated uniformly and almost in one layer with three types of negatively charged translucent developers: blue (hereinafter also referred to as B), green (hereinafter also referred to as G), and red (hereinafter also referred to as R). do. At a position where the photoreceptor and the transparent conductive substrate are closest to each other, for example, blue and red light are simultaneously irradiated from the side opposite to the developer carrying surface of the transparent conductive substrate 21. Since the developer is placed in the middle of the optical path, the developer acts as a light filter before the light reaches the photoreceptor. The blue and red light passes through the blue and red developers, respectively, and reaches the photoreceptor.

On the other hand, the surface of the photoreceptor is previously charged with a charger 35 to have a polarity opposite to that of the developer, that is, to be positively charged. Further, a DC bias is applied between the conductive substrate 23a of the photoconductor and the transparent conductive substrate 21 by a power source 36 so that the photoconductor side is negative. Further, the amount of charge of the charger 35 on the surface of the photoreceptor is set so that the potential is higher than that of the transparent conductive substrate 21 (0 potential). At the location where the blue light and red light reach the photoreceptor, the positive charges on the surface of the photoreceptor are discharged and the potential becomes lower than that of the transparent conductive substrate 21. This situation is shown in FIG.

In FIG. 12, V _O indicates the potential of the transparent conductive substrate 21 (0 potential), and V _A indicates the surface potential of the photoreceptor 23. In FIG. Also, V _L is the bright area of the photoreceptor after exposure, and V _D
indicates the surface potential of the dark area. Furthermore, V _B indicates the potential of the conductive substrate 23a of the photoreceptor.

As a result of the above, at the position where the photoreceptor is irradiated with blue light and red light, the potential V _L is the potential of the conductive substrate.
Since it is more negative than V _O , the negatively charged developer remains attracted to the transparent conductive substrate 21 side. In addition, since the green developer does not transmit blue light or red light, the potential V _D on the photoreceptor surface is still high at the green developer position.
The green developer adheres to the surface of the photoreceptor 23.
In this way, a green image is obtained on the photoreceptor, and a mixed color image of blue and red is obtained on the conductive substrate. Furthermore, if the light source for providing exposure is, for example, green light, green developer remains on the transparent conductive substrate 21, and other developers adhere to the photoreceptor. In the present invention, by selecting the light source for irradiation, it is possible to freely select the color of the developer deposited on the photoreceptor or the transparent conductive substrate.

FIG. 13 shows a sectional view of a more specific device of this embodiment. 3 is a lens, 2 is a scanner, 27 is a half mirror, 28 is a developer coating device which is a developer carrier, 35 is a charger, 30 and 36 are power sources, 9 is a static elimination lamp, and 31 is a laser light source. The developing device 28 may be of any type commonly used, but a so-called two-component developing device in which BGR mixed developer and iron powder are mixed is most suitable. Blue, green, and red developers are highly resistive colored particles that are triboelectrically charged. If this developer is positively triboelectrically charged, contrary to the embodiment shown in FIG. A charger 35 uses a photoconductive layer to negatively charge the surface of the photoreceptor.

FIG. 14 is a modification of the embodiment shown in FIG. 13, in which a transparent conductive substrate 37 is fixed instead of the transparent conductive substrate 21, and a thin transparent insulating film 38 is moved. The apparatus shown in FIG. 14 can also be applied as an embodiment apparatus of the present invention whose principle is shown in FIG.

Now, in FIGS. 13 and 14, a DC bias is applied between the developing device 28 and the transparent conductive substrate 21 or 37 with the transparent conductive substrate side being positive. By adjusting the applied bias, the BGR mixed developer that is negatively triboelectrically charged on the developing device can be coated almost uniformly on the transparent conductive substrate. The mixed developer is sent toward the photoreceptor, and at a position where the photoreceptor and the transparent conductive substrate are closest to each other, a signal-modulated light beam is exposed from the transparent conductive substrate side to form an image as described above. Each of the light sources 31 is a laser that generates BGR light, but it may also be an LED or other light source, or it may be a white light source equipped with a color filter and supply BGR light.
Each light source independently participates in image writing. For example, both a blue developer and a green developer, in which blue light and green light are generated simultaneously, adhere to the transparent conductive substrate 21 or the insulating film 38 . The image thus formed may be transferred to paper or the like using the device shown in FIG. 10 to make a hard copy, or it may be displayed as is using the device shown in FIG. 8 or 9. Good too.

The colored developer used in the present invention is obtained, for example, by mixing a resin with a dye. It is preferable that the developer used has as high a color saturation as possible. When the color density of the developer is high, the filter effect of the developer becomes even stronger by increasing the exposure of the corresponding light source. Using three light beams of the three primary colors of light, blue-violet, green, and red,
It is best to use a mixed developer containing a red developer. Furthermore, since the developer is attracted to the photoreceptor by weak charges generated within the photoreceptor and forms a color image, the developer can be easily removed from the photoreceptor. Furthermore, it is not always necessary to mix three colors of developers; for example, in order to obtain a two-color display, two-color developers and corresponding two-color light sources may be used. Furthermore, if it is desired to display four or more colors, a necessary number of light sources and a developer having a transmission spectrum characteristic that selectively transmits each light source are mixed with the necessary number of colors.

As described in detail above, according to the present invention, a multicolor pictorial image can be obtained by one shot exposure, and the capacity for information display can be increased. Further, when the apparatus is used only for display without providing a hard copy, an economical apparatus can be obtained without consuming developer.

[Brief explanation of the drawing]

FIGS. 1 to 4 are schematic diagrams of a conventional image forming apparatus, FIGS. 5 and 6 are explanatory diagrams of the configuration of one embodiment of the present invention, and FIGS. 7 to 10 are further diagrams of a conventional image forming apparatus. A schematic diagram of a specific device, FIG. 11 is a configuration explanatory diagram of another embodiment of the present invention, FIG. 12 is a graph showing the potentials of the photoreceptor and the conductive substrate, and FIGS. 13 and 14.
The figure is a schematic diagram of a more specific device of the embodiment of FIG. 11. In the figure, 1... Laser light source, 2... Scanner, 3... Lens, 21... Transparent conductive substrate, 2
2... Mixed developer, 23... Photoreceptor, 24, 29
. . . bias power supply, 26 . . . charger, 28 . . . developer.

Claims (1)

[Scope of Claims] 1. In an image forming method in which a color image is formed by irradiating optical information onto a developer prepared by mixing a plurality of colored developers each having a different transmitting wavelength, the state of light transmission varies depending on the wavelength. Unlike,
A mixed developer is used, which is a mixture of colored developers of multiple colors that hold charges of specific polarity, the mixed developer is supported by a support, and a potential difference is created between the mixed developer and the electrophotographic photoreceptor. A plurality of light beams with different wavelengths are irradiated onto the photoconductor from the side of the mixed developer, and the charges of the colored developer and the charges on the photoconductor are changed depending on the wavelength of the irradiated light beams. An image forming method characterized by forming a color image by generating charges of opposite polarity and selectively electrostatically adsorbing colored developers to a photoreceptor according to the wavelength of the irradiation. 2. In an image forming device that forms a color image by irradiating optical information onto a developer that is a mixture of a plurality of colored developers that each transmit different wavelengths, the state of light transmission differs depending on the wavelength.
A transparent conductive substrate member that holds charges of a specific polarity and supports a mixed plurality of colored developers in a thin layer state, a conductive substrate and a photosensitive layer, and the photosensitive layer side is placed on the transparent conductive substrate member. an electrophotographic photoreceptor facing the developer; an optical means for irradiating a plurality of light beams with different wavelengths from the transparent conductive substrate member side toward the photosensitive layer of the photoreceptor; and the transparent conductive substrate member and the photoreceptor. a power source that generates a potential difference between the conductive substrate of the body, and according to the wavelength of the irradiated light beam,
A color image is formed by generating a charge on the photoconductor with the opposite polarity to the charge possessed by the developer, and selectively electrostatically adsorbing the colored developer to the photoconductor according to the wavelength of the irradiation. Characteristic image forming device.