JPS61145576A - Correcting method of surface potential of photosensitive body - Google Patents

Abstract

PURPOSE:To hold the surface potential of a photosensitive body which is fatigued according to use constant and to prevent deterioration in picture quality in long-period use by moving and controlling an electrostatic discharger according to the degree of the fatigue of the photosensitive body. CONSTITUTION:The degree of fatigue of the photosensitive body is detected through the detection, etc., of sensors for the counted value of the quantity of copies, counted value of the rotating speed of the photosensitive body, or the surface potential of the photosensitive body, and the discharging lamp 6 is rotated around the shaft 6a through a driving coil 8, solenoid 7, etc., according to the degree of fatigue, so that the lamp 6 leaves an electrostatic charger uniformly. Consequently, the residual charge cancellation time of the photosensitive body becomes long and trap charges are reduced to prevent a decrease in surface potential, thereby holding the surface potential of the photosensitive body constant. therefore, the deterioration of the photosensitive body which is fatigued according to its use is prevented substantially to form an image of good quality even during long-period use.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method of keeping constant the surface potential of a photoreceptor that becomes fatigued with the use of a copying machine.

<Prior art and its drawbacks> A photosensitive material such as selenium is used in the photoconductor of a copying machine, but this photosensitive material causes optical fatigue due to repeated exposure and charging, and also due to friction with copying paper and cleaners. Causes mechanical surface fatigue. For this reason, when a copying machine is used for a long period of time, the performance of the photoreceptor deteriorates due to the fatigue described above, and the potential during uniform charging decreases, causing blurring and loss of density in the copied images. There were some drawbacks.

<Object of the Invention> In view of the above drawbacks, it is an object of the present invention to provide a surface potential correction method for keeping constant the surface potential of a photoreceptor whose performance has deteriorated due to long-term use.

<Configuration and Effects of the Invention> The present invention is characterized in that fatigue of a photoreceptor of a copying machine is detected, and a static elimination lamp is moved in accordance with the degree of fatigue.

With the above configuration, according to the present invention, the following effects can be achieved.

Due to the deterioration of photoreceptor performance due to long-term use of copiers,
When the potential during uniform charging decreases, uniform charging can be achieved by moving the static eliminating lamp to change the irradiation intensity of the static eliminating light, or by changing the time from irradiation with the static eliminating light to uniform charging. It is possible to correct the current potential to a normal value, thereby extending the life of the photoreceptor.

<Embodiment> FIG. 2 is a structural diagram of a main part of a copying machine that implements a surface potential correction method according to an embodiment of the present invention. Around the photoreceptor 1, there is a charger 2. Developing device 3. Transfer charger4. A cleaning layer 5 and a static elimination lamp 6 are installed.

FIG. 1 is an enlarged view of the vicinity of the static elimination lamp G of the copying machine. The static eliminating lamp 6 is installed near the charger 2, and is rotatably supported around a rotating shaft 6a as a fulcrum. Move between the position and the position of the dashed line.

FIG. 3 is a block diagram of the main parts of the drive device. This figure is a view from the back side of FIGS. 1 and 2. This drive device includes a drive coil 8. Consists of a solenoid 7 and a drive circuit 9,
When the drive circuit 9 receives a static elimination lamp movement signal from a control section (not shown), a current is applied to the drive coil 8 so as to move the static elimination lamp 6 to a predetermined position between the solid line position and the broken line position. . The solenoid 7 moves up and down by the magnetic force caused by the current applied to the drive coil 8. Since this solenoid 7 is connected to the lever 6b of the static elimination lamp 6, the static elimination lamp 6 rotates around the rotating shaft 6a.

Further, the control section includes a counter for counting the number of copies, and each time the count reaches a certain number of copies, it forms a charge removal lamp movement signal and outputs it to the drive circuit 9.

FIG. 4 is a diagram showing the change in potential when the photoreceptor is uniformly charged as the number of copies increases. The broken line indicates a change in the surface potential of the photoreceptor when the surface potential is not corrected. According to this, as the number of copies increases, the surface potential decreases.

In order to correct the surface potential using the above mechanism, the static eliminating lamp 6 is rotated from the solid line position to the broken line position in FIG. Control is performed to shift it away from the charger 2. As a result, the time necessary for canceling the residual charges can be saved, and the amount of trapped charges can be reduced. Therefore, as the photoreceptor 1 deteriorates, by gradually rotating the static elimination lamp 6 in the clockwise direction in FIG. 1, the surface potential can be stabilized.

The graph shown by the solid line shows the change in the photoreceptor surface potential when the above-mentioned surface potential correction control is performed. In this embodiment, each time the number of copies reaches a certain number, the static elimination lamp 6
is rotated by a certain angle in the position direction shown by the broken line in FIG. Therefore, as shown in FIG. 4, a decrease in the surface potential of the photoreceptor 1 is suppressed and a substantially constant potential can be maintained.

In this embodiment, the static eliminating lamp 6 is configured to rotate around the rotating shaft 6a, but the static eliminating lamp 6 can also be moved vertically from the photoreceptor to increase or decrease the irradiation distance. Similar effects can be obtained, and
Substantially the same effect can be obtained by moving the photoreceptor in the circumferential direction and increasing or decreasing the distance to the charger.

In order to detect the degree of fatigue of the photoreceptor, in this embodiment, the number of copies is counted, and each time the counted value reaches a certain value, it is determined that the photoreceptor is fatigued to the extent that the potential needs to be corrected. However, in addition to this detection method, the degree of fatigue of the photoreceptor can also be detected by a method that counts the number of rotations of the photoreceptor, a method that uses a sensor that detects the surface potential of the photoreceptor, or the like.

[Brief explanation of the drawing]

FIG. 1 is an enlarged view of the vicinity of the static elimination lamp of a copying machine that implements the method for correcting the surface potential of a photoreceptor according to the present invention, FIG. 2 is a structural diagram of the main parts of the copying machine, and FIG. FIG. 4, which is a block diagram of the main parts of the apparatus, is a diagram showing the relationship between the number of copies made by the copying machine and the surface potential of the photoreceptor. 1-Photoconductor, 6-Static elimination lamp, 7-Solenoid, 8-Drive coil, 9-Drive circuit.

Claims (5)

[Claims] (1) A surface potential correction method characterized by detecting fatigue of a photoreceptor of a copying machine and moving a static elimination lamp according to the degree of fatigue. (2) The surface potential correction method according to claim 1, wherein the static elimination lamp is rotated. (3) The surface potential correction method according to claim 1, wherein the static elimination lamp is moved perpendicularly to the photoreceptor. (4) The surface potential correction method according to claim 1, wherein the static elimination lamp is moved in the circumferential direction with respect to the photoreceptor. (5) The surface potential correction method according to any one of claims 1 to 4, wherein the degree of fatigue of the photoreceptor is detected depending on whether the number of copies has reached a certain number.