JPS6132080A - Transfer device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To utilize effectively a discharge area for a transfer, also to execute a transfer in a discharge charge state, and to obtain a transfer efficiency equal to a usual paper in a high moisture content form by providing a member for guiding a form to the surface of a photosensitive drum in an area where a transfer efficiency of a corotron is high. CONSTITUTION:A form guide member 5 is provided so that it is adjacent to a photosensitive drum 1, and also the tip is projected into a transfer corotron 2. When transferring an image, a photosensitive drum 1 on which a toner image has been formed rotates and moves an image surface to a transfer position, and on the other hand, a form is guided to a position adjacent to the transfer position by a paper chute 4, and guided so as to contact to the surface of the drum 1 on which an image has been formed, by the member 5. Subsequently, immediately after passing through the member 5, the form receives a discharge action of the transfer corotron 2 from its rear side, and the toner image on the drum 1 is transferred to the form.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a transfer device for an electrophotographic copying machine, and relates to a transfer device that can obtain the same transfer effect even with water-containing paper as with plain paper. , 2-Regarding improvement of bar chute section.

(Prior art) Conventionally, in electrophotographic copying machines, a transfer device that overlaps a sheet of paper with an image on a photosensitive drum and transfers the toner image onto the sheet by applying corona discharge from the back side of the sheet using a transfer corotron has been common. It is used in many ways.

When the image is transferred by this transfer device, if the paper contains a relatively large amount of moisture, for example about 8% moisture, the specific resistance of the paper decreases, and it takes one pursuit to guide the paper to the transfer section. The corona charge escapes through the transfer line, causing a drop in the transfer voltage, resulting in a transfer failure.

In order to prevent such transfer defects, according to the prior art, a low antibody of, for example, about 100 MΩ is inserted into the ground circuit of the pursuit that guides the paper to the transfer area in order to prevent the transfer voltage from dropping. Measures are being taken to prevent the corotron's corona discharge from being lost.

However, this method requires a very complicated mechanism to provide a resistor in the grounding circuit of the paper chute, which may cause failures.

(Problems to be Solved by the Invention) The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a transfer device that has a relatively simple configuration and can obtain the same transfer effect even with water-containing paper as with plain paper. It is about providing.

(Means for Solving the Problems) That is, the above-mentioned object of the present invention is to superimpose a sheet of paper on the image on the photosensitive drum, and perform corona discharge from the back side of the sheet using a transfer corona discharge device to generate the image on the sheet. In a transfer device of an electrophotographic copying machine that performs transfer, a paper guide member at the tip of a paper chute that guides transfer area washing paper is placed close to a photosensitive drum and protrudes into a region of high transfer efficiency of a corona discharge device. This is achieved by a transfer device of an electrophotographic copying machine characterized by the following.

(Function) When the transfer device is configured as described above and the paper is conveyed to the transfer area, the paper is transferred to the toner image on the photosensitive drum in the high transfer efficiency area of the corona discharge device by the paper guide member at the tip of the paper chute. The toner image on the photosensitive drum is completely transferred to the paper because the toner image on the photosensitive drum is completely transferred to the paper immediately after the photosensitive drum contacts the paper and passes through this paper guide member.

(Example) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing essential parts of a transfer device according to the present invention.

In Figure 1, 1 is a drum-shaped electrostatic charge retaining material (
(hereinafter referred to as a photosensitive drum), which rotates clockwise in this embodiment. Reference numeral 2 is a transfer corotron which is arranged in close proximity to face the photosensitive drum 1 and performs corona discharge toward the photosensitive drum 1; 3 is a corona wire; 4 is a transfer area formed by the photosensitive drum 1 and the transfer corotron 2; A harbor chute 5 for guiding paper (not shown) is a paper guide member attached to the tip of the paper chute 4 facing the photosensitive drum l. The paper guide member 5 is provided close to the photosensitive drum 1 so that its leading end projects into the transfer corotron 2.

Note that, according to the present invention, the fan paper guide member 5 and the photosensitive drum 1
The gap A between the sheet guide member 5 and the
It has been found that the distance C from the tip of the corona wire 3 to the corona wire 3 is preferably set to 5 mm or less.

Further, as the material of the paper guide member 5, stainless steel, which has excellent rust prevention properties, is used like the paper chute 4.

When image transfer is performed using the transfer device configured as described above,
The photosensitive drum 1 on which the toner image is formed rotates (clockwise)
to move the image surface to the transfer position.

On the other hand, the paper is guided by the a-bar chute 4 to a position close to the transfer position, and is guided by the paper guide member 5 so as to come into contact with the surface of the photosensitive drum 1 on which the image is formed. Immediately after the paper passes through the guide member 5, it is subjected to the discharge action of the transfer corotron 2 from the back side of the paper to the photosensitive drum l.
The upper toner image is transferred to the paper.

FIG. 2 is a graph showing experimental results when image transfer was performed using the transfer device of the present invention.

In the graph, the solid line indicates the transfer device according to the present invention, and the broken line indicates the case of the conventional device cited for comparison. Further, the moisture content of ordinary plain paper is 6 to 7%, and transfer is not performed when the moisture content is 10% or more.

As is clear from the graph in Figure 2, with the transfer device of the present invention, even if the moisture content increased, transfer efficiency was approximately the same as that of plain paper, whereas with the conventional device, the moisture content of the paper increased. As it increases, the transfer efficiency decreases rapidly.

In this embodiment, stainless steel, which has excellent rust prevention properties, is used as the material for the paper guide member 5, but it is more preferable to use a material with insulation properties, sliding properties, ease of processing, etc. .

Further, the paper guide member 5 may be provided integrally with the paper chute 4.

(Effects of the Invention) As described above, according to the transfer device of the present invention, by providing the paper guide member that guides the paper to the photosensitive drum surface in the area of the transfer corotron where the transfer efficiency is high, the discharge area of the transfer corotron can be improved. Used very effectively for transcription,
In addition, since the transfer is performed in a state where the discharge from the transfer corotron is always at its maximum, the transfer effect equivalent to that of plain paper can be obtained even on paper with a high moisture content.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main part of a transfer device according to an embodiment of the present invention, and FIG. 2 is a graph illustrating the results of an experiment in which transfer was performed using the transfer device shown in FIG. Symbols in the figure: 1...Photosensitive drum 2...Transfer corotron 3
... Corona wire 4 ... Paper chute 5
...Paper guide member (3 other people) Figure 1 Figure 2 Figure 1 Includes wood〒(%)

Claims (1)

[Claims] In a transfer device of an electrophotographic copying machine, a sheet of paper is superimposed on an image on a photosensitive drum, and a corona discharge device for transfer performs corona discharge from the back side of the sheet to transfer the image onto the sheet of paper.
A transfer device for an electrophotographic copying machine, characterized in that a paper guide member at the tip of a paper chute that guides paper to a transfer area is located close to a photosensitive drum and protrudes into a high transfer efficiency area of a corona discharge device. .