JPS58115463A - Transfer failure preventing device of electrophotographic system printing device - Google Patents

Abstract

PURPOSE:To prevent transfer failure even in case of transfer paper to which a small quantity of paper powder has adhered, by using a destaticizing device in the vicinity of a transfer part. CONSTITUTION:A printing form 1 which has adhered paper powder onto the surface is fed in the direction as indicated with an arrow by upper and lower paper feed tractors 12. A destaticizing device 13 is installed so as to be opposed to the whole width direction of a loaded printing form. When the printing form 1 is opposed to the destaticizing device 13, static electricity of the paper surface is eliminated, and as a result, electric attracting force between the paper powder and the surface of the printing form is eliminated, and the paper powder is separated from the surface of the printing form 1. The printing form 1 contacts only with a cover 14 as a result of running, therefore, the paper powder which has lost attractive force to the surface of the printing form passes under the cover 14 by vibration of the form in the course of running, and drops in the opposite direction to the running direction of the form.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing transfer defects caused by spark discharge in a high voltage application section of a transfer mechanism section of an electrophotographic printing apparatus.

As is well known, an electrophotographic printing device connected to a computer uses a charging mechanism to charge the surface of a photosensitive drum rotating at a constant speed, and then exposes it to light-modulated laser light to create static electricity on the surface of the photosensitive drum. An electrostatic latent image is formed, the electrostatic latent image is developed by a developing machine, and when a potential is generated in front of the printing paper, the electrostatic latent image is transferred to the printing paper by a transfer mechanism. FIG. 1 shows an example of the principle of the vicinity of the photosensitive drum. this house,
A thin wire made of metal is stretched between the transfer mechanism section and the charging mechanism section, and a high voltage is applied to the wire.

Continuous folding paper is generally used in printing devices connected to electronic computers because of its high speed. This paper generates fine paper dust during processing such as cutting, punching, and perforation, but most of the paper dust is removed by the paper manufacturer. However, there are cases where 100% of the dust is not removed and a small amount remains on the paper surface.

Paper powder generally has a resistivity of 101·Ω·Ω or higher and can be considered a non-conductive substance, but depending on the type of paper, its resistivity may be low. When the paper dust adhered to the paper surface is carried to the transfer mechanism section, it invades the vicinity of the wire that is stretched over the transfer mechanism section and to which a high voltage is applied. High voltage is generally applied with reference to the casing. The paper pushing mechanism in FIG. 1 is made of metal and is structurally at the same potential as the housing. Therefore, as mentioned above, if paper dust with low resistivity enters the vicinity of the wire in the transfer mechanism, the dielectric strength between the wire and the paper extrusion mechanism will substantially decrease, and spark discharge will occur between the two. do. When a spark discharge occurs, the voltage of the wire decreases, resulting in a transfer failure and a printing failure. It must be said that printing defects are fatal to printing devices.

An object of the present invention is to prevent transfer defects such as those described in the prior art even when paper with a small amount of paper dust attached is used.
In other words, the purpose is to prevent printing defects from occurring.

The points of view of the present invention are as follows.

(1) The manner in which paper powder adheres to the paper surface is electrostatic. That is, the electrostatically charged paper powder is adhered to the paper surface by the electrical attraction between the paper powder and the paper surface.

(if) Therefore, by removing this electric attraction force, the paper powder adhering to the paper surface can be separated from the paper surface. A static eliminator may be used as a means for removing the electrical attractive force.

(b) Therefore, it is only necessary to provide a static eliminator at a place where the paper powder separated from the surface of the paper is not carried to the transfer mechanism section by the running paper.

FIG. 2 is a diagram showing an embodiment of the present invention.

This figure is an enlarged view of the vicinity of the transfer mechanism.

In the figure, 1 is a printing paper, 2 is a photosensitive drum, 5 is a paper extrusion mechanism, 4 is a transfer mechanism, 5 is a transfer wire to which high voltage is applied, 12 is a paper feed tractor, 13 is a static eliminator, 14
is a cover.

When a printing operation is performed, printing paper is fed in the direction of the arrow shown in the figure by a paper feed tractor one page above and below. A running printing paper 1 is brought into close contact with a photosensitive drum 2 by a paper pushing mechanism 5.

The image on the surface of the photosensitive drum 20, which rotates at a circumferential speed equal to the paper feed speed, is transferred onto the printing paper 1 in front of the transfer mechanism 4. Static eliminator 1
5 has a length sufficient to cover the width of the maximum print paper that can be loaded.

Assume that printing paper with paper dust attached to the surface is loaded. The printing paper 1 is sent in the direction of the arrow by upper and lower paper feed tractors 12. Since the static eliminator 15 is installed to face the entire width of the loaded printing paper, when the printing paper 1 faces the static eliminator 15, the static electricity on the paper surface is removed, and as a result, paper dust and the surface of the printing paper are separated. The electrical attractive force between them is removed and the paper dust leaves the surface of the printing paper 1.

Since the printing paper 1 only comes into contact with the cover 14 as a result of running, the paper particles that have lost their adhesion to the surface of the printing paper pass under the cover 14 due to the vibration of the paper while the paper is running, and are moved in the paper running direction. falls in the opposite direction.

As a result, the paper powder passes through the paper extrusion mechanism 6 to the transfer mechanism 4.
It is almost impossible for the transfer wire 5 to enter the vicinity of the transfer wire 5. Therefore, the transfer wire 5 to which a high voltage is applied
This prevents the dielectric strength between the casing and the paper pushing mechanism 6, which is at the same potential, from decreasing, and a spark discharge occurs between the two, resulting in a transfer failure due to a drop in the voltage of the transfer wire 5. It will no longer occur.

According to the present invention, paper powder electrostatically attached to the paper surface can be separated from the paper surface, and as a result, the amount of paper powder carried to the transfer mechanism section can be extremely reduced. Spark discharge between the wire to which voltage is applied and the paper extrusion mechanism is reduced due to a decrease in dielectric strength between the two, and therefore transfer defects due to voltage drop in the wire due to spark discharge are also eliminated. be able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the vicinity of a photosensitive drum equipped with electrophotographic printing. FIG. 2 is a schematic diagram showing an embodiment of the present invention. In the figure, 1 is a printing paper, 2 is a photosensitive drum, 5 is a paper pushing mechanism, 4 is a transfer mechanism, 5 is a transfer wire, 15 is a static eliminator, and 14 is a cover. Name of patent applicant Hitachi Koki Co., Ltd. Figure 1'! = 2 figures

Claims (1)

[Claims] a photosensitive drum; a ninth electrically conductive paper pushing mechanism that brings the printing paper into close contact with the photosensitive drum during printing; In an electrophotographic printing device equipped with a transfer mechanism for transferring an image, the static eliminator is provided so that the non-printing surface of the printing paper reaches the paper extrusion mechanism after facing the static eliminator over its entire width. A device for preventing transfer defects in an electrophotographic printing device, characterized by: