JPS58211669A - Calibration of surface potential meter - Google Patents

Abstract

PURPOSE:To enable the easy and automatic calibration of a surface potential meter without using any special jigs, by generating a reference potential within an image region of a photosensitive body for the calibration of the surface potential meter. CONSTITUTION:A photosensitive drum 1 is charged by a corona charger 2 and then deelectrified by an image exposure light 3, and thereby a latent image is formed. Next, this latent image is transferred on recording paper 6 by a transfer charger 5 via a developer 4, while a toner remaining after transfer is collected by a cleaner 7. Meanwhile, a potential sensor 8 and a surface potential meter 9 read the dark and light potentials of the latent image and controls a variable high-voltage power source 11 and a development bias power source 12 so as to stabilize the quantity of a picture. On the other hand, a reference potential for calibrating the surface potential meter is formed on the photosensitive drum 1 by using an exposure light source 13 having a sufficient quantity of light for deelectrifying uniformly the surface of a photosensitive body on the photosensitive drum 1, and based on the reference potential, a false control of the surface potential meter 9 due to a drift is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for calibrating a reference potential of a surface potential needle in an electrostatic recording device such as an electrophotographic device incorporating a surface electrometer.

Conventionally, in electrostatic recording devices such as electrophotography, in order to prevent image deterioration due to potential drift due to the environment and deterioration of the photoreceptor, 1. A surface electrometer is installed in the electrostatic recording device to monitor the potential of the photoreceptor, and if the potential deviates from a certain set value, the corona current applied to the photoreceptor, the image exposure amount, or the time of development is determined. There is a known method for keeping images stable by controlling the developing bias voltage.

However, this method has the disadvantage that if the surface electrometer itself drifts due to dirt or environmental conditions, the image immediately deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose a method for calibrating a surface electrometer that solves the problem of surface electrometer drift as described above.

The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a photosensitive drum is charged with corona by a corona charger, and then subjected to charge removal by exposure light J to form a latent image. do. Next, this fa image is visualized by a developer 41 and transferred onto a recording paper O by a transfer charger j. The remaining toner after transfer is sent to the cleaner 7 and is not collected. Furthermore, the dark potential and bright potential of the latent image are read by the potential sensor and surface potential meter, the detection signal is processed by the microcomputer IO, and the output is fed back to the variable high voltage power supply and/or the developing bias power supply. Yes, that's K.
The corona charger is feedback-controlled by changing the voltage of the stain source //, and the current charger is feedback-controlled by the power source, thereby stabilizing the image quality.

The above configuration relates to the conventionally known control method described above. In the present invention, in addition, a reference potential for calibrating the surface electrometer is formed on the photosensitive drum; Prevents erroneous control due to drift of the electrometer 2. For this purpose, in the present invention, as shown in FIG.
In order to create a reference potential, an exposure light source/J having a sufficient amount of light to uniformly neutralize the surface of the photoreceptor on the photoreceptor drum/J is provided. It uses amorphous silicon photoreceptors, which are becoming more and more practical. The present inventor has investigated that some amorphous silicon photoreceptors have a surface potential of /Q lX after being charged to about zoov in a dark area.
It has been found that the present invention can be carried out using a photoreceptor that can remove residual potential to about a to +V by applying visible light of about -5ee.

In this example, a photosensitive drum / having an amorphous silicon photoreceptor mounted on a conductive substrate as described above is used, and an exposure light source /3 is installed at an appropriate position near the exposure area of image 1 to perform image exposure. During the previous, so-called pre-rotation, the exposure light source/
In step 3, irradiate the light source with light to approximately 0.
The static electricity is removed to V, this value is read as a reference potential by the surface electrometer 9, and the zero point of the electrometer is adjusted. That is, the output from the electrometer 9 relative to the above-mentioned reference potential is read into the microcomputer 10 as a calibration dark potential, the reading of the electrometer 9 is corrected based on that value, and the power supply it and 7.
2 control is performed.

Note that in order to calibrate the electrometer, the microcomputer 10 may be used as described above. 7, potential sensor t
It is easy to directly calibrate the circuit of the electrometer 9 using the reference potential output detected by the sensor.

Furthermore, the exposure light source /J may be installed at any desired position on the outer periphery of the photosensitive drum /, but as it moves away from the potential sensor g, the pre-rotation time becomes longer, so in that case, the post-rotation The surface electrometer may be calibrated on the rotating surface of the drum by omitting the pre-rotation by stopping all corona charging and rotating the photosensitive drum by one rotation while performing exposure at the time of .

Furthermore, when a laser is used to obtain one image exposure light 3, the output of the laser may be increased and used in place of the exposure light source /J.

FIG. 1 shows another embodiment of the present invention. In this example, one end of the changeover switch/da is connected to the conductive substrate of the photosensitive drum/, and the ground terminal l on the other switching side is connected to the ground wire/6K.
, and the reference power supply terminal 17 is connected to the reference paper pressure generation power supply /II/
C Connect.

The changeover switch 14I is connected to the ground terminal /3 during printing. When calibrating the surface electrometer, zero point calibration is first performed with the switch LD connected to the ground terminal 1 to eliminate drift.

After that, while exposing the photosensitive drum l with the exposure light source /J, manually or using a relay (not shown), switch the connection switch /i to the reference power supply terminal 1tVc on the side of the reference voltage generation power supply /j to connect the surface potential meter. Perform the gain adjustment in step 9.

As described above, according to the present invention, it is possible to easily and automatically calibrate a surface potential meter without using a special jig, and it is possible to calibrate a surface potential meter easily and automatically without using a special jig. control can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the invention, and FIG. 1 is a diagram showing another embodiment of the invention. l...Photosensitive drum, -...Corona belt container,
3...Image exposure light, Da...Desk 1#V device, S.
...Transfer charger, 6...Transfer paper,
Ward 7...Cleaner, S...Potential sensor, -9°°°Surface potential needle.
Gland 10... Microcomputer, /l... Variable high voltage power supply, /Co... Developing bias power supply, /J... Exposure light source, /41... Changeover switch, /S... Ground terminal, /6 ...
Ground wire, /7...Reference power supply terminal, l...Reference power supply.

Claims (1)

[Scope of Claims] 1) In an electrostatic recording apparatus having a photoreceptor capable of performing silent recording and a surface electrometer for detecting the surface potential of the photoreceptor, a reference potential is generated in an image area of the photoreceptor. A method for calibrating a surface potential meter, characterized in that the surface potential needle is calibrated using the reference potential. 2) A method for calibrating a surface electrometer according to claim 1, characterized in that the photoreceptor is exposed to light and the reference potential is made approximately equal to the potential of a conductive substrate supporting the photoreceptor. . 5) The method for calibrating a surface potential meter according to claim 1 or 1, wherein the photoreceptor is amorphous silicon. 4) Support the photoreceptor with a conductive substrate, measure the output of the surface electrometer with respect to the potential of the conductive substrate and the third potential, and calculate the drift and gain of the surface potential needle, respectively. A method for calibrating a surface electrometer according to claim 2 or 3, which comprises calibrating a surface electrometer.