JPH0462664B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention forms a two-tone electrostatic latent image by irradiating a photoconductor with light images of two different light intensities. , this electrostatic latent image relates to an electrostatic recording device in which the electrostatic latent images are developed by toners charged with opposite polarities.

(B) Prior art An electrostatic recording device is an electrostatic recording device in which a two-tone electrostatic latent image is formed on the same photoreceptor, and the two-tone electrostatic latent image is developed with toners of different colors. , for example, is disclosed in Japanese Patent Application Laid-Open No. 55-59473.

In this conventional technique, a two-tone electrostatic latent image is formed on a photoreceptor having a surface insulating layer, and the entire surface of the photoreceptor is exposed to light in a stage prior to a developing process.

(c) Problems to be solved by the invention As mentioned above, in the conventional technology, a special photoreceptor having a surface insulating layer is used, so the entire surface of the photoreceptor is exposed to light in a stage before the development process Requires means.

Therefore, a special photoreceptor and exposure means are required.
Higher prices were unavoidable.

Furthermore, since there was only one developing machine, it was difficult to prevent color mixing.

(d) Means for solving the problems The present invention provides a first charging means for charging a photoconductor that can be charged to both polarities to one polarity, and
light irradiation means for irradiating light images of two types of light intensities onto the photoreceptor to form an electrostatic latent image of two gradations of mutually different potentials on the photoreceptor charged by the charging means; and a second charging means for charging the electrostatic latent image formed by the light irradiation means to a polarity opposite to that of the first charging means, and charging by the second charging means. This electrostatic recording apparatus is equipped with a developing means for developing an electrostatic latent image on a photoreceptor using two types of toner charged with mutually opposite polarities.

(e) Effect In the present invention, an electrostatic latent image of one polarity is formed by the first charging means and the light image of the higher and lower light intensity, and the electrostatic latent image of one polarity is formed by the first charging means and the light image of the higher and lower light intensity. The higher light image forms an electrostatic latent image of opposite polarity. When each of the electrostatic latent images is developed with toners charged with opposite polarities, different toners are attracted to each electrostatic latent image by Coulomb force.

Therefore, when two color toners are charged to opposite polarities and developed, a two-tone toner image can be obtained.

(f) Embodiment FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing the surface potential of a photoreceptor and the state of toner adhesion.

In FIG. 1, reference numeral 1 denotes a photoreceptor drum whose circumferential surface is coated with amorphous silicon as a photoreceptor that can be charged in both polarities, and rotates in the direction of the arrow (clockwise). Slightly upstream from the top of the photoreceptor drum 1, there is a first electrode for uniformly charging the photoreceptor drum 1 to +700V.
A positive corotron 2 is provided as a charging means.

On the next process side of the plus corotron 2, there is provided a light emitting diode array 3 in which light emitting elements are closely arranged in the same direction as the rotational axis of the photoreceptor drum 1. This light emitting diode array 3 is configured to be able to emit a light image with high light intensity and a light image with low light intensity. Note that the desired two-tone image is formed by an area where no light image is irradiated and an area where a light image with high light intensity is irradiated.

On the next process side of the light emitting diode array 3, there is a unit for uniformly charging the photosensitive drum 1 to -400V.
A negative corotron 4 is provided as a second charging means, and when the negative corotron 4 is operated with respect to the photoreceptor drum 1 which has been charged to +700V by the positive corotron 2, the photoreceptor drum The charging potential on 1 is +300V.

A black developing machine 5 in which negatively charged black toner is stored is provided on the next process side of the negative corotron 4, and a positively charged red toner is stored in the next process side of this black developing machine 5. A red developing machine 6 is provided.

A transfer roller 8 is pressed against the bottom of the photosensitive drum 1 for transferring a black toner image and a red toner image onto the recording paper 7 .

A cleaning device 9 for removing residual toner and a discharge lamp 10 for erasing residual charges are provided on the next process side of the transfer roller 8.

When the positive corotron 2 operates, the photosensitive drum 1 is uniformly charged to +700V (FIG. 2A).

When two types of light images with different light intensities are irradiated by the light emitting diode array 3 onto the photoreceptor drum 1 which is charged to +700V, the area irradiated with the light image with high light intensity is The potential drops to +100V, and the potential of the area irradiated with the light image of low light intensity drops to +400V (Figure 2B). Therefore, at this stage, a three-tone electrostatic latent image is formed.

Thereafter, when the negative corotron 4 operates on the photoreceptor drum 1 on which the electrostatic latent image is formed, the potential of the electrostatic latent image is biased to the negative side by 400 V, and the area that is not irradiated with the light image is +300V,
The area irradiated with the light image of low light intensity becomes 0V, and the area irradiated with the light image of high light intensity becomes -300V (Fig. 2C).

Then, negatively charged toner adheres to the area where the potential is +300V (Fig. 2D), and -300V
The positively charged toner adheres to the area (FIG. 2E).

Therefore, the area that is not irradiated with any light image by the light emitting diode array 3 is developed with black toner, and the area that is irradiated with a light image of high light intensity is reversely developed with red toner. .

In this way, the two-color toner image formed by the black toner and the red toner is transferred onto the recording paper 7, and a desired recorded matter is completed.

(g) Effects of the Invention In the present invention, an ordinary photoreceptor without a surface recording layer is used, and a means for exposing the entire surface of the photoreceptor to light is not required in the step before the transfer process, so it is an inexpensive method.
A color electrostatic recording device can be realized.

Also, if a developing machine is provided separately for each charging polarity,
Color mixing can be easily prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing surface potential. 1... Photosensitive drum, 2... Plus corotron (first charging means), 3... Light emitting diode array (light irradiation means), 4... Minus corotron (second charging means), 5, 6 ...Developing machine.

Claims (1)

[Claims] 1. A first charging means for charging a photoreceptor that can be charged to both polarities to one polarity, and two gradations of mutually different potentials on the photoreceptor charged by the first charging means. a light irradiation means for irradiating a photoreceptor with light images of two different light intensities to form an electrostatic latent image; A second charging means for charging the electrostatic latent image on the photoreceptor charged by the second charging means is charged with two types of electrostatic latent images charged with mutually opposite polarities. An electrostatic recording device comprising a developing means for developing with toner.