JPH05303286A - Separator for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To provide a separator capable of separating a transfer paper from a photosensitive body, even if an electrification current for separating is not increased. CONSTITUTION:In this electrophotographic copying machine supplying toner to an electrostatic latent image formed on the photosensitive body 11, to obtain a visible image, transferring the visible image on the transfer paper P by a transfer electrifier 23, and destaticizing the transfer paper having the completion of the transfer, by a separating electrifier 24, to separate the transfer paper from the photosensitive body, a guiding member 22 disposed on a side opposite to the photosensitive body 11 of the separating electrifier 24, and preventing the transfer paper P from being entered into the electrifier 24, is made electrical conductivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separating device for separating a transfer paper from a photoconductor in an electrophotographic copying machine.

[0002]

2. Description of the Related Art Toner is supplied to an electrostatic latent image formed on a photoconductor to form a visible image, and the visible image is transferred onto a transfer paper by a transfer charger, and then separated onto a transfer paper after transfer. 2. Description of the Related Art Electrophotographic copying machines in which charge is removed by a charger to separate transfer paper from a photoconductor are well known.

In the transfer type copying machine, the transfer paper 6
0 is separated from the photoconductor 61 through a process as shown in FIG. The photoconductor 61 is made of, for example, aluminum 61a and selenium 61b, and
It is grounded as shown in (a). Then, when the visible image (toner image) formed on the photoconductor 60 according to the copying process is transferred to the transfer paper 60, an electric charge (positive) is applied to the back surface of the transfer paper 60 by the action of the transfer charger. At the same time, the charge of the opposite polarity (negative) to the back surface of the photoconductor 61
Is induced.

Therefore, the induced charge (negative) and the transfer paper 6
By the electrostatic force F1 between the electric charges (positive) applied to 0,
The transfer paper 60 adheres to the surface of the photoconductor 61 as if it were attached to the surface thereof, so that it becomes difficult to separate the transfer paper 60. Therefore, a separating charger is arranged at a position downstream of the transferring charger in the sheet passing direction of the transfer sheet to perform corona discharge, and the charge (positive) on the back surface of the transfer sheet 60 is neutralized to form the transfer sheet 60. The applied charges are weakened so that the electrostatic force becomes F2 (<F1). As a result, as shown in FIG. 6C, the transfer paper 60 is separated from the photoconductor 61 by virtue of its own rigidity (strength of the waist) H and its own weight W overcoming the electrostatic force F2.

[0005]

In order to realize a copy speed that has been recently demanded, in a copying machine in which transfer and separation are performed as described above, the corona discharge of the separating charger causes transfer paper to be transferred. There is not enough time to work.
However, if the current value of the corona discharge of the separation charger is increased, it is possible to separate the transfer paper from the photoconductor, but conversely, the discharge at the time of the transfer paper separation from the photoconductor becomes stronger, which is a phenomenon called a print. Occur.

Therefore, as a means for avoiding such a phenomenon, a separation claw which is a transfer paper separation assisting means is provided at a position downstream of the separation charging device, and the separation must be performed by the claw. .. The separation method using the separation claw has a problem that a nail mark is generated at the front end of the image although reliable separation can be expected.

Therefore, an object of the present invention is to provide a separating device which can separate a transfer paper from a photoconductor without generating a print.

[0008]

According to a first aspect of the invention, toner is supplied to an electrostatic latent image formed on a photoconductor to form a visible image, and the visible image is transferred onto a transfer paper by a transfer charger. In an electrophotographic copying machine in which transfer is performed and charge is removed from the transferred transfer paper by a separation charger to separate the transfer paper from the photoconductor, the separation charger is disposed on the side facing the photoconductor. The guide member for preventing the transfer paper from entering the charger is electrically conductive.

The invention of claim 2 is characterized in that the guide member is grounded.

The invention of claim 3 is characterized in that the guide member has a curvature on the side facing the photoconductor.

According to a fourth aspect of the present invention, the guide member is formed of a metal plate, and a surface facing the separation charger is covered with an insulating member.

According to a fifth aspect of the present invention, the guide member is formed of resin, and a conductive material is vapor-deposited on the surface facing the photoconductor.

According to a sixth aspect of the present invention, a part of the conductive guide member extends downstream from the casing of the separating charger in the sheet passing direction of the transfer sheet, and guides the transfer sheet conveyance. It is characterized in that it is a conveying member.

[0014]

When the separation charger is operated after the toner increase is transferred from the photoconductor to the transfer paper, the transfer paper is transferred to the photoconductor by the electrostatic attraction force of the conductive guide member and the charge and polarization on the transfer paper. Separated from the surface.

In the third aspect of the present invention, the guide member having a curvature makes the electrostatic attraction force large by separating the transfer paper from the photoconductor by narrowing the space.

In the fifth aspect, the guide member having the conductive member vapor-deposited only on the surface facing the photosensitive member increases the distribution ratio of the separating charger to separate the transfer paper.

In the sixth aspect of the present invention, the guide member extending to the rear of the casing guides the separated transfer paper while applying electrostatic attraction force in a wide range.

[0018]

The present invention will be described in detail below with reference to the illustrated embodiments.

In FIG. 1, reference numeral 1 indicates the entire electrophotographic copying machine. A document placing table 2 made of transparent glass is arranged on the upper surface of the copying machine. An exposure optical system 10 including an illumination light source lamp 4, movable mirrors 5, 6 and 7, which reciprocate in the direction of an arrow, a lens block 8 and a fixed mirror 9 which are movable in the optical axis direction, is located below the document table 2. Are arranged. The optical system 10 forms an image of the document on the surface of the photoconductor 11 by optically scanning the document placed on the document table 2.

The photoconductor 11 is rotationally driven in the direction of the arrow,
First, the charger 12 is charged to a predetermined polarity, and then the exposure optical system 10 slit-exposes the original image to form an electrostatic latent image. The electrostatic latent image is formed by the toner supplied by the developing device 13. The image is visualized, and then the charge is removed by the pre-transfer charge removing lamp 14.

On the other hand, the transfer papers P are taken out one by one from the selected paper feed cassettes 15 and 16 by the feed rollers 17 and 18, and are guided to the registration rollers 21 through the paper guide portions 19 or 20. Registration roller 21
Is guided to the transfer portion X in synchronization with the visible image forming area of the photoconductor.

The transfer paper P sent to the transfer section X is brought into close contact with the surface of the photoconductor 11 at a portion facing the transfer charger 23, and the visible image on the surface of the photoconductor is produced by the action of the charger 23. Is transcribed. Transfer paper P on which a visible image is transferred
Is weakened by the action of the separating charger 24 to weaken the electrostatic force between the transfer paper and the photoconductor 11, and is guided and transferred to the transfer paper transfer path 25 with the guide member 22 as a guide. A separation claw 31 for assisting separation of transfer paper is provided at a position downstream of the separation charger 24 in the rotation direction of the photoconductor.

The guide member 22 includes a transfer sheet separating charger 2.
4 is provided with a function of preventing it from entering the inside, and details of the configuration thereof will be described later.

The transfer paper P separated from the photoconductor 11 is sent to a fixing device 26 provided on the transfer paper transport path 25 to fix a visible image, and then, a discharge tray is discharged by a discharge roller 27. It is discharged to 28. Also, the photoconductor 2 after transfer
Removes the residual toner remaining on the surface of the cleaning device 2
After being removed by 9, the residual charge is erased by the static elimination unit 30 that simultaneously irradiates the static elimination corona discharge and the static elimination lamp to prepare for the next image forming step.
A transfer paper conveying device 32 that conveys the separated transfer paper is disposed between the separating charger 24 and the fixing device 26.

Now, the structure of the guide member 22 will be described in detail. In FIG. 2, a plurality of guide members 22 are arranged in the width direction of the photoconductor 11 (perpendicular to the drawing). The separation charger 24 includes a casing 24a and a separation charger 24b, and irradiates a corona discharge having a predetermined polarity toward the photoconductor 11, specifically, the back surface of the transfer paper P that is in close contact with the photoconductor. ..

In FIG. 2, the guide member 22 is made of a conductive material and has a curved surface 22a formed by curving the surface facing the photoconductor 11. The guide member 22 is grounded. The guide member 22 is fixed by fitting the engaging grooves 22b and 22c formed at the front and rear ends thereof to the upper edge of the casing 24a.

Guide member 2 provided with conductivity and curvature
2 is capable of quickly separating the transfer paper P from which charge has been removed from the surface of the photoconductor by the action of the electrostatic attraction of the conductive portion. The efficiency is best when the curvature of the curved surface 22a of the guide member is the same as the curvature of the surface 11a of the photoconductor 11.

A guide member for preventing the transfer paper from entering the charging device has been conventionally installed, but it is provided in the opening of the casing of the charging device in a flat shape, and the guiding member It is provided in a direction away from the peripheral surface of the photoconductor in the rotation direction. Although it is advantageous to utilize the curvature of the photoconductor to separate the transfer paper from the photoconductor, the range of the corona discharge emitted from the separation charger 24b, in other words, the electrostatic attraction force of the separation charger 24, is reduced. It is desirable that the distance of influence on the photoconductor is as short and wide as possible. In that respect, the surface 2 of the guide member 22 in the present invention
The curvature of 2a allows the electrostatic attraction force for separating the transfer paper to act efficiently over a wide range.

Another configuration of the guide member will be described with reference to FIG. The guide member 22A is formed by covering the metal plate 22Aa with a cover member 22Ab made of an insulating resin. The edge of the metal plate 22Aa facing the photoconductor has a curved surface 22A.
c is formed to have the same curvature as the peripheral surface of the photoconductor, and this curved surface is not covered by the cover member. The cover member 22Ab may be formed to match the shape of the metal plate 22Aa. Alternatively, it may be formed by molding a metal plate. In this example, the cost of the guide member can be reduced.

The guide member 22B shown in FIG.
b is formed of an insulating resin, and a conductive material 22Ba is formed on the curved surface facing the photoconductor by vapor deposition. In the example shown in FIG. 4, compared with the example shown in FIG. 3, the distribution ratio of the separating charger 24 can be increased and the leakage margin can be increased, so that efficient transfer sheet separation can be expected.

FIG. 5 shows a guide member 22C suitable for a copying machine having a structure in which it is difficult to provide a curved guide member between the photoconductor 11 and the separating charger. The guide member 22C includes a transfer paper entry prevention portion 22Ca stretched across the opening of the casing 24a and a transport guide portion 22Cb as a transport member extending downstream from the casing in the transfer paper passing direction. Is becoming The transfer paper entry prevention portion 22Ca and the conveyance guide portion 22Cb are formed of an integral conductive material. Needless to say, this guide member 22C is grounded. The conveyance guide portion 22Cb guides and conveys the separated transfer paper toward the transfer paper conveyance device 32 forming a part of the transfer paper conveyance path 25.

In the example shown in FIG. 5, since it does not have a curved portion, it tends to gradually separate from the photoconductor 11 in the sheet passing direction of the transfer paper, but the transport guide portion 22Cb has the casing 2 formed therein.
By extending from 4a to the downstream side, a wide range of electrostatic attraction force is exerted on the transfer paper, so that the same action and effect as the guide member having a curvature can be obtained. Moreover, the separation charger 24
Since it also serves as a guide member between the transfer sheet conveying device 32 and the transfer sheet conveying device 32, the number of parts can be reduced.

[0033]

As described above, according to the first aspect of the present invention, by making the guide member conductive, it is possible to suppress the generation of prints without increasing the output of the separating charger and to transfer the transfer paper. It can be separated from the photoreceptor.

According to the third aspect, when the guide member has a curvature, the distance between the photoconductor and the guide member becomes small, and the transfer paper can be efficiently separated.

According to the fourth aspect, since the guide member is made of metal and is covered with resin, cost reduction can be realized.

According to the fifth aspect, since the conductive material is vapor-deposited only on the surface facing the photoconductor, the distribution ratio of the separating charger can be increased and the leakage margin can be increased.

According to the sixth aspect of the present invention, even in a copying machine in which it is difficult to dispose a curved object between the photoconductor and the guide member, the electrostatic attraction force for separation is applied in a wide range. The
Allows reliable transfer paper separation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an electrophotographic copying machine equipped with a separation device of the present invention.

FIG. 2 is an enlarged front view of a separation device showing an embodiment of the invention according to claims 1, 2, and 3.

FIG. 3 is an exploded perspective view showing an example of a guide member according to claim 4;

FIG. 4 is a perspective view showing an example of a guide member according to claim 5;

FIG. 5 is a perspective view showing an example of a separation device according to claim 6;

FIG. 6 is a cross-sectional view for explaining the principle that the transfer paper is separated from the photoconductor.

[Explanation of symbols]

 11 ... Photoconductor 23 ... Transfer charger 24 ... Separation charger 24a ... Casing 24b ... Separation charger 22 ... Guide member 22a ... Curved surface 22Aa ... Metal Plate 22Ab ... Cover member 22Ac ... Curved surface 22B ... Guide member 22Ba ... Conductive substance 22C ... Guide member 22Ca ... Transfer paper entry prevention part 22Cb ... Conveyance guide part P. ..Transfer paper

Claims (6)

[Claims] 1. A toner is supplied to an electrostatic latent image formed on a photoconductor to form a visible image, the visible image is transferred to a transfer paper by a transfer charger, and the transferred transfer paper is separated. In an electrophotographic copying machine in which charge is removed by a charger to separate transfer paper from a photoconductor, the transfer paper is disposed on the side of the separating charger facing the photoconductor and the transfer paper enters the charger. A separating device for an electrophotographic copying machine, characterized in that a guide member for preventing the occurrence of electric shock is made conductive. 2. The separation device for an electrophotographic copying machine according to claim 1, wherein the guide member is grounded. 3. The separation device for an electrophotographic copying machine according to claim 1, wherein the guide member has a curvature on the side facing the photoconductor. 4. The separation device for an electrophotographic copying machine according to claim 1, wherein the guide member is formed of a metal plate, and a surface facing the separation charger is covered with an insulating member. .. 5. The guide member is made of resin,
2. The separation device for an electrophotographic copying machine according to claim 1, wherein a conductive material is vapor-deposited on the surface facing the photoconductor. 6. A part of the conductive guide member extends to the downstream side of the casing of the separating charger in the sheet passing direction of the transfer sheet, and serves as a conveying member for guiding the transfer sheet. The separating device for an electrophotographic copying machine according to claim 1, wherein