JPS60143375A - Electrophotographic copying device - Google Patents

Abstract

PURPOSE:To form an excellent image which has no fog at the ground part even after numbers of copies are taken by carrying out principal electrostatic charge, exposure, and development in the 1st turn of a photosensitive body, and performing transfer electrostatic charge, cleaning, and destaticizing in the 2nd turn successively. CONSTITUTION:The principal electrostatic charge, exposure, and development are carried out in the 1st turn of the photosensitive body. In the 2nd turn, toner sticking on the surface of the photosensitive body is scraped off with a cleaning blade after the transfer is carried out by the transfer electrostatic charge and then the destaticizing is performed lastly. Consequently, even if toner sticks on the photosensitive body surface, the surface is cleaned with the cleaning blade, so there is no toner sticking on the photosensitive body surface after the cleaning regardless of whether a developer deteriorates or not, and no fogging appears at the ground part even after numbers of copies are taken repeatedly, thereby forming an excellent image.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to an electrophotographic copying apparatus, in particular, to complete a series of electrostatic copying steps during two rotations of the photoreceptor using a rotating photoreceptor. The present invention relates to an electrophotographic copying device.

Conventional Structure and Problems A two-rotation, one-process system in which a series of electrostatic copying steps is completed during two rotations of a rotary photoreceptor has been proposed in Japanese Patent Laid-Open Publication No. 11537/1983. In this system, an example in which a main charging function and a transfer charging function are repeatedly used in a zero and one corona charger is described in Japanese Patent Publication No. 55-37755.

It is also known that such a system has advantages such as the ability to easily downsize the copying apparatus.

The configuration of such a two-rotation, one-process copying apparatus will be described. FIG. 1 shows the configuration of a conventional two-rotation, one-process copying apparatus. The following mechanisms are arranged around the photoreceptor 1, which rotates counterclockwise, in the direction of rotation of the photoreceptor, starting from a charger 2 that faces the right side of the photoreceptor 1 in the drawing.

○Charging unit 2: Performs all main charging functions for forming a latent image during the first rotation of the photoconductor, and performs the main charging function for forming a latent image during the second rotation of the photoconductor, for image transfer to the transfer target. A device that performs the transfer charging function.

○Optical system 3°゛・Performs image exposure in the first of two rotations of the photoreceptor.

○Static charger 4゛・One that performs alternating current discharge during the second rotation of the photoreceptor.

○Developing device 5・P・Magnetic brush development in which a bias potential sufficient to remove toner from the background of the image is constantly applied, and the development of the latent image and the cleaning of the surface of the photoreceptor are performed alternately with each rotation of the photoreceptor. Device.

In addition, a fixing device 6 for fixing the image transferred to the transfer object. and switch 7 + 8k (jii + getting.

゛The operation of the conventional two-rotation, one-process copying apparatus configured as described above is as shown in Fig. 2, in which main charging, exposure, and development are performed in the first rotation, and transfer is performed in the second rotation. To perform all charging, neutralizing, and cleaning operations, or to stop the copying operation, press switch 7 after the second rotation is complete.
is opened, and the photoreceptor rotates once and stops while the charger 2 is not operating.

As described in U.S. Pat. No. 2,911,330, the arrangement of the charger, optical system, charger for static elimination, and developing device in the two-rotation, one-process copying apparatus described above is as follows. The mechanism is based on the fact that when the photoreceptor holds an electrostatic latent image, the developing action is performed, and when the photoreceptor is neutralized, the entire cleaning action is performed, and both the developing action and the cleaning action are performed. .

Cleaning is the process of removing toner remaining on the photoreceptor without being transferred by 10% to the transfer object when the toner image 'fc on the photoreceptor is transferred to the transfer object. Otherwise, when the next copy is made, toner will adhere to the background of the image, causing a phenomenon called "fogging" and impairing the image quality. Cleaning by the magnetic flage mechanism is performed by rubbing a magnetic brush formed by magnetic force against the surface of the photoreceptor from which the static charge has been removed. However, as the series of copying steps is repeated many times, the developer in the developing device will run out. As a result, cleaning with the magnetic brush is not performed sufficiently, and the next electrostatic copying step is carried out with toner still attached to the surface of the photoreceptor. - When copying is performed many times, with the conventional two-turn, one-process type electrophotographic copying machine, "fogging" during leaning is limited to the two-turn, one-process method; This problem overlaps with "fogging" at the time of zero image development, which is a problem common to all electrophotographic copying apparatuses, and causes a significant deterioration in image quality. If the image quality is severely degraded,
This requires the troublesome work of draining out all the developer in the developing device and replacing it with new developer, which is disadvantageous for serviceability.

OBJECT OF THE INVENTION The object of the invention is to provide a two-rotation, one-process type electrophotographic copying apparatus which is advantageous in terms of serviceability and has minimal fogging on the background of images even after repeated copying operations. That's true.

Structure your invention. expert. 1 month□1. . . Along the circumferential surface of the photoreceptor, which rotates twice during the process, there is a charger that has both the main charging function for forming a latent image and the transfer charging function for transferring the image to the transfer target, and a charger that performs exposure. As the photoreceptor rotates, the photoreceptor is rotated, and the developing device, which is equipped with a cleaning blade on the side where the photoreceptor exits within the device housing, and the power saving device act on each function on the photoreceptor in the above-mentioned order. and during the first rotation of the photoreceptor, the main charging, exposure and development functions are activated, and during the second rotation, the transfer charging, cleaning and static elimination functions are activated. This is because K fj is formed in such a way that it is possible to obtain an image with less "fogging" in the background area even after repeating the copying process 8 many times.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows a schematic configuration of a two-rotation, one-process type electrophotographic copying apparatus according to an embodiment of the invention. In FIG. 3, the photoreceptor 1 has a drum-shaped photoconductor layer, and the photoreceptor 1 rotates counterclockwise twice to complete one electrostatic copying process. . The photoreceptor 1 has the same structure as a photoreceptor commonly used in the past.
It is set according to the circumference and the longest value of the recorded image that requires copying. Along the circumferential surface of the photoreceptor 1,
Starting from the charger 2 facing the right side of the photoreceptor 1 in the drawing,
An optical system 3. A developing device 10 and a static elimination lamp 1°1 are arranged. The charger 2 is a well-known charger using corona discharge, and can be switched to an appropriate voltage when the applied voltage is main charging or transfer charging. 1, this charger 2 constitutes a part of the transfer device together with a transfer material supply device (not shown), and is provided with a well-known heat roll fixing device 8.

The optical system 3 is the same as the conventional one. The developing device 10 has a magnetic brush mechanism, and a bias potential sufficient to remove toner from the background portion of the image is applied thereto. The developing device 1o is also equipped with a cleaning blade 9 that operates on the photoconductor exit side of the housing, that is, after the photoconductor passes through the magnetic brush mechanism. This cleaning blade 9 does not work during the first rotation of the photoreceptor;
It works in the second rotation. The charge eliminating lamp 11 operates during the second rotation of the photoreceptor, and removes the charge from the photoreceptor.

The operation of the electrophotographic copying apparatus according to the embodiment of the present invention constructed in this manner will be described with reference to FIG.

During the first rotation of the photoreceptor, main charging, exposure, and development are sequentially performed as the photoreceptor 1 rotates, and the cleaning blade 9 and the charge removal lamp 11 do not operate. In the second rotation, after the transfer is performed, the photoreceptor passes through the optical system 3 on which no light is projected, and the toner adhering to the surface of the photoreceptor is scraped off by the cleaning blade 9 inside the housing of the developing device 1o. Cleaning is performed by dropping the battery, and finally, the static elimination lamp 11 is turned on to eliminate static electricity. The cleaning blade 9 is a well-known one, and the toner scraped off by the cleaning blade 9 is used again in the developing device. ' When copying is performed continuously as described above, the first rotation and the second rotation are repeated alternately, and when copying is to be stopped, the charger is turned on after the second rotation is completed. The photoreceptor 1 rotates once and then stops while the cleaning blade 9 and the static elimination lamp 11 continue to operate.

Here, each mechanism starts or stops its operation when the position corresponding to the leading edge of the image on the photoreceptor rotates to the position where each mechanism is arranged in synchronization with the rotation of the photoreceptor.

In a two-rotation, one-process type electrophotographic apparatus configured in this way, even if toner adheres to the surface of the photoreceptor when it passes through the developing device in the second rotation, the cleaner is removed afterwards.
Because cleaning is performed using a cleaning blade, toner does not adhere to the surface of the photoreceptor after cleaning, regardless of whether the developer has deteriorated or not. Since the surface of the photoreceptor is always thoroughly cleaned before proceeding to the electrostatic copying process, if the developer deteriorates, the conventional structure
Compared to an electrophotographic copying apparatus using a one-rotation process type, images with less "1 fog" can be obtained.

Further, the toner scraped off by the cleaning plate can be reused without requiring a complicated mechanism.

In addition, in the above-mentioned embodiment, the method of static elimination may be replaced with a known static elimination charger instead of the total static elimination lamp.

Further, the photoreceptor is a drum-shaped, sorted photoreceptor that has been processed into an endless belt. Even the configuration in which functional devices are arranged is not difficult.

Effects of the Invention As described above, the uninvented electrophotographic copying apparatus has a main charging function for forming a latent image and a transfer target along the circumferential surface of the photoreceptor, which rotates twice during one electrostatic copying process. The transfer charging function for image transfer to the body -e*= The charger used, the optical system for exposure, the developing device equipped with a cleaning blade metal fitting on the side where the photoconductor exits inside the device housing, and the entire static eliminator. , are arranged so that each function is applied to the photoreceptor in the above order as the photoreceptor rotates;
iJ photoreceptor During one rotation of photoreceptor, royal charging and exposure.

This is a 2-rotation, 1-process type electrophotographic recording device configured in such a way that the developing functions are activated, and during the second rotation, the transfer charging, cleaning, and static elimination functions are activated. For example, compared to a two-rotation, one-process type electrophotographic copying apparatus having a conventional configuration, an excellent effect of reducing "fogging" on the background area after copying is performed many times is obtained. As a result, the new developer deteriorates as it is copied over and over again, causing "fog" to appear on the image, resulting in a significant loss of image quality and the tedious task of replacing the developer. It is possible to obtain the effect of extending the period of use of copies of the same drawings, and by extension, the service life is excellent, and the copying cost is reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a conventional two-rotation, one-process type electrophotographic copying device, FIG. 2 is an explanatory diagram of the operation of the electrophotographic copying device of FIG. 1, and FIG. 3 is an embodiment of the invention. 2 rotations 1
FIG. 4 is a schematic diagram of the process type electrophotographic recording apparatus, and FIG. 4 is a clear diagram of the operation hS2 of the same embodiment. 1 Photoreceptor, 2 Charger, 3 Optical system, 9 Cleaning plate, 10 Developing device, 11. Static elimination lamp. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2A! f、'；＊'Electronic eight-dimensional cleaning Figure 3

Claims (1)

[Claims] A charger having both a main charging function for forming a latent image and a transfer charging function for transferring an image to a transfer target along the circumferential surface of the photoreceptor that rotates twice during one electrostatic copying process; The optical system that performs exposure, the developing device that is fully equipped with a cleaning blade on the side where the photoconductor exits inside the device housing, and the static eliminator.
As the photoreceptor rotates, each function is applied to the photoreceptor in the above-mentioned order, and during the first rotation of the photoreceptor, the main charging, exposure, and development functions are applied. 1. An electrophotographic copying apparatus characterized in that the electrophotographic copying apparatus is configured such that transfer charging, cleaning, and static elimination functions are activated during the second rotation.