JPH0246484A - Electrifying device for electrophotographic device - Google Patents

Abstract

PURPOSE:To shift the reversely polar potential of the photosensitive body surface, which is caused by a transfer electrode, to polarity with light sensitivity and to prevent fogging and irregularity in printing density by providing an auxiliary electrification electrode between a cleaner and a destaticizing lamp. CONSTITUTION:A laser beam 4 produces the potential difference between a part subjected to laser exposure and an unexposed part after it exposes. Afterward, the transfer electrode 6 electrifies with polarity opposite from an electrification electrode 2, and the part subjected to laser exposure is electrified to polarity without light sensitivity. However, the part is again electrified to polarity with light sensitivity by the auxiliary electrification electrode 10. Consecutively, the destaticizing lamp 12 uniformly attenuates the surface potential of the photosensitive body 1. After the photosensitive body 1 is again electrified by the electrification electrode 2, its surface potential becomes uneven. By providing the auxiliary electrification electrode 10, fogging and irregularity in density can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electrophotographic process of a printing apparatus using an electrophotographic method.

[Background of the invention]

Generally, the process of an electrophotographic apparatus includes a charging electrode 2 for charging the surface of a photoreceptor 1 to a constant potential, and a laser beam for attenuating the potential at any location on the surface of the photoreceptor 1, as shown in FIG. 4, a developing device 5 for visualizing the potential unevenness (latent image) on the surface of the photoreceptor 1 using the laser beam 4, and a 1-ner 1 electrostatically attached to the surface of the photoreceptor 1.
a transfer electrode 6 for transferring the toner 13 onto a sheet of paper; a cleaning device 9 for removing toner 13, paper powder, etc. remaining on the photoreceptor 1 after passing through the transfer electrode from the surface of the photoreceptor 1;
Static elimination lamp 1 for eliminating potential remaining on the surface
It consists of 2.

FIG. 4 shows the change in potential on the surface of the photoreceptor in such a process. As shown in the figure, the potential of a portion that receives laser exposure once attenuates to around Ov and is once negatively charged by the transfer electrode 6, the negative potential does not attenuate even when exposed by the static elimination lamp 12, and the laser The exposed area and the laser non-exposed area have non-uniform potentials after the charging electrode 2. For this reason, there has been a drawback that the toner 13 adheres to non-printing areas in the developing section, and uneven adhesion of the toner 13 also occurs in the printing section, resulting in fogging and uneven printing density.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to eliminate image defects such as fog and uneven printing density.

[Summary of the invention]

In the present invention, when the surface of a photoconductor is charged to a photosensitivity pole, as long as sufficient static elimination light is provided by a static elimination lamp regardless of the magnitude of the potential of the photoconductor surface, a certain level peculiar to that photoconductor can be applied. Focusing on the fact that the potential on the surface of the photoreceptor decreases to the electric potential, if the surface of the photoreceptor is charged to a pole with no photosensitivity, it is charged again to a pole with photosensitivity, and then the photoreceptor is It is designed to make the surface potential uniform.

[Embodiments of the invention]

FIG. 1 shows a configuration showing an embodiment of the present invention.

In the figure, a photoreceptor 1 is charged by a charging electrode 2, and then exposed to laser light 4 to form an electrostatic latent image.
The developing device 5 supplies toner 13 to the photoreceptor 1 to visualize the electrostatic latent image, and the transfer electrode 6 transfers the developed image to the paper 8. After that, the cleaning device 9 removes the remaining image, and the auxiliary charging electrode 10
After pre-charging the light-sensitive pole with
2, the potential on the surface of the photoreceptor 1 is uniformly attenuated, and the photoreceptor 1 is transferred to the charging electrode 2 again.

FIG. 3 schematically shows changes in the potential on the surface of the photoreceptor 1 due to the electrophotographic process of the present invention.

In the figure, due to laser exposure, a certain potential difference is generated between the laser non-exposed area and the laser exposed area in the potential after the laser exposure. Thereafter, the transfer electrode 6 charges the charging electrode 2 with a polarity opposite to that of the charging electrode 2, and the laser-exposed area is charged with a polarity that has no photosensitivity.
The surface potential of the photoreceptor 1 is charged again by the auxiliary charging electrode 10 to a photosensitive pole, the surface potential of the photoreceptor 1 is uniformly attenuated by the static elimination lamp 12, and the surface potential of the photoreceptor 1 is uniform after being charged again by the charging electrode 2. Become.

In the embodiments of the present invention, an electrophotographic device is used in which the positive electrode is a photosensitized photoreceptor, a positive charging electrode, a positive toner, a negative transfer electrode, and a positive auxiliary charging electrode are combined. A similar effect can be expected with a combination of a photosensitivity photoreceptor, a negative charging electrode, a negative toner, a positive transfer electrode, and a negative auxiliary charging electrode.

〔Effect of the invention〕

According to the present invention, by providing the auxiliary charging electrode between the cleaning device and the static elimination lamp, it is possible to shift the reverse polarity potential on the surface of the photoreceptor due to the transfer electrode to a photosensitive pole, so that the static elimination lamp This makes the potential on the photoreceptor surface uniform,
Fog and uneven print density can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus showing an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a conventional electrophotographic apparatus. FIG. 3 is a schematic diagram showing changes in surface potential of a photoreceptor in one embodiment of the present invention. FIG. 4 is a schematic diagram showing changes in surface potential of a photoreceptor in a conventional example. In the figure, 1 is a photoreceptor, 2 is a charging electrode, and 3 is a power source (A
), 4 is a laser beam, 5 is a developing machine, 6 is a transfer electrode, 7 is a power source (B), 8 is paper, 9 is a cleaner 10 is an auxiliary charging electrode, 11 is a power source (C), 12 is a static elimination lamp, 13 is toner. Patent applicant name Hitachi Koki Co., Ltd.

Claims (1)

[Scope of Claims] 1. In a process in which a photoreceptor of an electrophotographic apparatus using a reversal development method repeats charging, exposure, development, transfer, cleaning, and static elimination exposure, there is no A charging device for an electrophotographic apparatus, comprising an auxiliary charging electrode having the same polarity as the charging electrode. 2. A process in which the transfer electrode charges the surface of the photoreceptor to a polarity opposite to that of the charging electrode, and the auxiliary charging electrode slightly charges the surface of the photoreceptor to the same polarity as the charging electrode. A charging device for an electrophotographic apparatus according to claim 1.