JPH01185584A - electrophotographic equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to electrophotographic devices such as copying machines, facsimiles, and printers. In particular, forming an electrostatic latent image on a photoreceptor,
A rotating developing roller disposed near the photoreceptor carries toner to the surface of the photoreceptor, the toner turns the electrostatic latent image on the photoreceptor into a visible image, and the visible image is transferred onto a transfer material. It relates to an electrophotographic device.

BACKGROUND OF THE INVENTION Generally, in the above-mentioned electrophotographic apparatus, a discharge device called a charger, a discharge charger, etc. is used to apply electric charge to a photoreceptor. This discharge device discharges the charge to be applied to the photoreceptor and also generates ozone.

By the way, photoreceptors are made of organic photoconductors (OPC), inorganic photoconductors, etc., but these conductors are deteriorated by ozone, and in some cases, there is a risk that cracks may occur on the surface of the photoreceptor. There is. In particular, when the photoreceptor is in the form of a belt, the photoreceptor belt is stretched in the circumferential direction and the width direction (direction perpendicular to the circumferential direction), so that the above-mentioned cracks are likely to occur. When the photoreceptor deteriorates or cracks occur, abnormal images such as image blurring and image blurring occur in the electrostatic latent image formed on the photoreceptor and the toner image transferred onto the transfer material. do.

Purpose The invention of each claim aims to provide an electrophotographic apparatus that can prevent the occurrence of abnormal images due to deterioration, cracking, etc. of a photoreceptor.

The invention according to claim 1 forms an electrostatic latent image on a photoconductor, carries toner to the surface of the photoconductor by a rotating developing roller disposed near the photoconductor, and uses the toner to form an electrostatic latent image on the photoconductor. An electrophotographic apparatus that converts an electrostatic latent image into a visible image and transfers the visible image onto a transfer material, the developing voltage applying means applying a voltage to a developing roller so that the toner is charged to a potential that does not adhere to a photoreceptor. and a photoconductor scraping member that uniformly and slightly scrapes the surface of the photoconductor to which toner is not attached.

The invention according to claim 2 is the electrophotographic apparatus according to claim 1, characterized in that a roller control means for stopping rotation of the developing roller is provided in place of the developing voltage applying means.

The invention according to claim 3 is the electrophotographic apparatus according to claim 1, characterized in that a roller separating means for moving the developing roller away from the photoreceptor is provided in place of the developing voltage applying means.

The present invention will be explained below using examples.

FIG. 1 is a side sectional view of an electrophotographic copying machine using a photoreceptor belt, which is an embodiment. In the figure, a document mounting table 1 made of a transparent member such as glass is placed on an original to be copied, and is placed at an arrow A.
It reciprocates in the A' direction, and the short-focus, small-diameter imaging element array 2 transfers the original image to the photoreceptor 4 (endless op) of the photoreceptor magazine 3.
A c-belt photoreceptor or a drum-type photoreceptor) is subjected to slit exposure through the opening slit 6 of the case 5. The charger 7 has a grid electrode 8 attached to the case 5.
The surface of the photoreceptor 4 is uniformly charged in cooperation with the photoreceptor 4.

The charged photoreceptor 4 is imagewise exposed by the element array 2, thereby forming an electrostatic latent image on the photoreceptor. This latent image is turned into a visible image by being supplied with toner from the developing device 9.

A transfer material, for example, a transfer paper P, is sent out by a paper feed roller 10, separated into one sheet by a conveyance separation roller 11, and one sheet of transfer paper is transferred to a registration roller 12.
sent to. The roller 12 feeds the transfer paper to the photoreceptor 4 so that the toner image on the photoreceptor and the transfer paper overlap. The toner image superimposed on the transfer paper is transferred onto the transfer paper under the discharge of the transfer charger 13. Thereafter, the transfer paper is separated from the photoreceptor 4 and moved to the fixing device 14, where it is fixed, and then the paper is transferred to the paper ejection roller 15.
is discharged onto the tray 16.

A cleaning device 17 is provided on the left side of the photoreceptor 4. The cleaning device 17 includes a cleaning blade 18 that removes residual toner on the photoreceptor 4, a seal 27 that prevents the toner that has fallen from the photoreceptor 4 from falling further downward, and a collection tank that collects the fallen toner. 2
4 is provided. The toner remaining on the photoconductor 4 after the transfer by the transfer charger 13 is completed is removed from the photoconductor by the cleaning blade 1B, transported to the collection tank 24 by the scraping member 26, and stored there.

The developing device 9 includes a developer tank 19 containing a developer (toner in the case of a -component type, toner and carrier in the case of a two-component type) and a developing roller 20 arranged near the photoreceptor 4. . The developing roller 2° rotates counterclockwise in the figure, and conveys the developer in the developer tank 19, and thus the toner, to the photoreceptor 4. Further, a bias voltage application circuit 21 as a development voltage application means is connected to the development roller 20. This circuit 21 applies an appropriate voltage to the developing roller 20, and by applying this voltage, the toner on the developing roller 20 is charged to an appropriate polarity and an appropriate magnitude. While the electrophotographic process consisting of the above-described series of steps of charging, exposure, development, transfer, and cleaning is being performed, especially while at least the developing step is being performed, the developing roller 2
0, a bias voltage application circuit is installed so that the electrostatic latent image on the photoreceptor 4 can be visualized with a desired density, and at the same time, the toner can be charged with enough charge to prevent the toner from transferring to the background area. An appropriate voltage is applied by 21.

Furthermore, in this embodiment, after the electrophotographic process described above is completed, while the cleaning blade 18 remains in contact with the photoreceptor 4, the operations of other devices for performing the electrophotographic process are stopped, and in particular, , from the developing device 9 to the photoreceptor 4
The photoreceptor 4 is rotated at least one rotation while no hetner is applied.

Generally, discharge devices such as the electrification charger 7 and the transfer charger 13 discharge charges toward the photoreceptor 4, but at the same time, they also generate ozone. This ozone deteriorates the surface of the photoreceptor 4 and may cause cracks in some cases. When such a situation occurs, abnormal images such as image blurring and image blurring occur in the image on the photoreceptor 4.

On the other hand, in this embodiment, as described above, after the electrophotographic process is completed, with the cleaning blade 18 in contact with the photoreceptor 4, the operation of each other device is stopped, and the toner application from the developing device 9 is stopped. The photoreceptor 4 is rotated while the light is shut off. By this operation, the surface of the photoreceptor 4 is scraped very slightly by the cleaning blade 18, and the layer deteriorated by ozone is removed from the photoreceptor.

This prevents cracking of the photoreceptor and, in turn, prevents image abnormalities. In this case, the application of toner to the photoreceptor 4 by the developing device 9 is blocked because if even a small amount of toner is present on the photoreceptor 4, the cleaning blade 1
This is because the small amount of toner will be present between the photoreceptor 8 and the photoreceptor 4, making it impossible to scrape off the photoreceptor 4 with the cleaning plate rta.

As is clear from the above description, the cleaning blade 18 functions to remove residual toner from the photoreceptor 4 during execution of an electrophotographic process, and functions to remove residual toner from the photoreceptor 4 when the electrophotography process is not executed. It functions as a photoconductor scraping member to uniformly and slightly scrape the surface of the photoconductor. In order to ensure that the cleaning blade 18 performs both of the above functions, the cleaning blade 18 is made of a relatively soft and wear-resistant material such as polyurethane rubber, and the relatively sharp angle portion of the light leakage is removed. It is convenient to make it lightly contact the photoreceptor 4.

However, regarding the material, shape, and way of contacting the cleaning blade 18 with the photoreceptor 4, certain specifications may be used as long as the cleaning blade 18 can uniformly and slightly scrape the surface of the photoreceptor 4 with no toner attached. It is not limited to things. In addition to the cleaning blade, a dedicated photoreceptor scraping member can also be provided.

During the scraping process on the surface of the photoreceptor 4, the developing device 9
There are several methods for blocking toner from being applied to the photoreceptor 4.

The first is the development roller 2 by the bias voltage application circuit 21.
By appropriately switching the magnitude and polarity of the voltage applied to 0, the toner on the developing roller 20 is charged to a potential that does not adhere to the photoreceptor.

Second, the rotation of the developing roller 20 is stopped and the agent tank 19 is
The supply of toner to the photoreceptor 4 is cut off.

Thirdly, a supporting means (not shown) for the developing roller 20 is separately provided to support the developing roller 20 so that it can be moved closer to or away from the photoreceptor 4, and the developing roller 20 is moved closer to the photoreceptor 4 during the electrophotographic process. 4, and move it away when the photoconductor is being taken up.

FIG. 2 is a graph showing the number of cracks on the photoreceptor when the surface of the photoreceptor is slightly scraped according to this embodiment, and the number of cracks that occur in a conventional device in which no scraping is performed.

Effects According to the present invention, deterioration, cracking, etc. of the photoreceptor are prevented, and high-quality images can always be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of one embodiment, and FIG. 2 is a graph showing the degree of cracking prevention of the photoreceptor. 4...Photoreceptor 2o...Developing roller P...
・Transfer material 21...Developing voltage application means 18...Photoconductor scraping member Fig. 2 (x) ON Funo May 17, 1988

Claims (3)

[Claims] (1) An electrostatic latent image is formed on the photoreceptor, and a rotating developing roller disposed near the photoreceptor carries toner to the surface of the photoreceptor, and the toner causes the electrostatic latent image on the photoreceptor to In an electrophotographic apparatus that converts a latent image into a visible image and transfers the visible image onto a transfer material, the toner comprises: a developing voltage applying means that applies a voltage to a developing roller so that the toner is charged to a potential that does not adhere to a photoreceptor; 1. An electrophotographic apparatus comprising: a photoconductor scraping member that uniformly and slightly scrapes off a surface of a photoconductor to which no photoreceptor is attached. (2) The electrophotographic apparatus according to claim 1, further comprising roller control means for stopping rotation of the developing roller in place of the developing voltage applying means. (3) The electrophotographic apparatus according to claim 1, further comprising a roller separating means for moving the developing roller away from the photoreceptor in place of the developing voltage applying means.