JPH09185218A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adequately control the charging potential by electrification of a photoreceptor so as to obtain a good image even though the heating heater of the photoreceptor is eliminated and the thermostating of a drum is eliminated by detecting the temperature of the photoreceptor and controlling the charging potential by electrification of the photoreceptor and/or a developing bias according to the detected temperature. SOLUTION: As to this electrophotographic system in which an amorphous silicon photoreceptor 1 is used; a temperature detecting means 13 detects the temperature of the surface or the vicinity of the photoreceptor 1, a control circuit 14 controls a power source 15 supplying a scorotron current based on the temperature information, and controls the current in accordance with the temperature of the photoreceptor 1. In the same way, the circuit 14 controls the power source 16 by the temperature detected by the means 13, so that a developing bias impressed on the sleeve 9 of a developing means 8 is controlled. Thus, since the temperature of the surface or the vicinity of the photoreceptor 1 is detected, and electrification and a developing condition are controlled in accordance with the characteristic of the photoreceptor 1 changing while depending on the temperature; stable image formation can be performed without depending on the environmental temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a charging voltage or a developing bias in a system adopting an electrophotographic system such as a printer, a facsimile and a copying machine.

[0002]

2. Description of the Related Art Up to now, a selenium drum or an organic photoconductor has been widely used as a photoconductor in an apparatus which employs an electrophotographic system. However, since the selenium photoreceptor is highly toxic and harmful, it was necessary to collect it after use. Further, in recent years, organic photoconductors have been explosively popularized because of low production cost. However, since the organic photoconductor has a short life, the organic photoconductor is incorporated in a replaceable unit as a cartridge so that it can be replaced frequently, and is discarded as it is.

In recent years, amorphous silicon drums have been developed and mass-produced in consideration of extending the life of the photoconductor. This amorphous silicon drum is produced by introducing monosilane gas in a vacuum container and forming an amorphous silicon layer on the conductive substrate by plasma glow discharge. The surface of this drum has a structure similar to that of glass, and since it is an inorganic semiconductor, it has high durability. Outside diameter is 3
It has a durability of 300,000 sheets or more when it is vertically fed in A4 size at 0 mm.

[0004]

However, this drum is
The surface resistance is lower than that of a conventional drum, and a phenomenon called "image deletion" occurs in which an electrostatic latent image is disturbed especially in high temperature and high humidity conditions. The "image deletion" easily occurs because the amorphous silicon forming the photoconductor is an inorganic material, and the formed amorphous silicon coating itself has a low surface resistance. That is, since the surface resistance is low, a current flows at the boundary between the potential portion and the low portion of the electrostatic latent image formed on the drum, and the potential contrast at the boundary portion becomes small, resulting in "image deletion".

In order to solve the above-mentioned problems, conventionally, a heater is mounted on the photoconductor to control the photoconductor to a temperature higher than the outside air temperature to reduce moisture adsorbed on the surface of the photoconductor to prevent "image deletion". I went. However, mounting a heater inside the rotating cylindrical drum requires sliding electrodes to energize the heater, making the device larger, increasing the cost, and turning on the machine power to increase the temperature. There was a system problem such as a long warm-up time.

Since the amorphous silicon drum is an inorganic semiconductor, its chargeability and exposure sensitivity have a high temperature dependency, and in a normal use environment, the charging potential changes greatly as shown in FIG. Figure 3 shows the Kyocera printer LS-6
5 is a plot of the surface potential of the photosensitive member with respect to the surface temperature of the photosensitive member of 500. As is apparent from the figure, it can be seen that the charging potential changes depending on the surface temperature of the photoconductor. As described above, in the case of the amorphous silicon drum, there is a problem that stable image formation cannot be performed because of temperature fluctuation.

For this reason, it is necessary to take measures such as heating and isolating the temperature of the photoconductor in addition to the measures against image deletion.

In order to solve the above-mentioned problems, the present invention is capable of controlling an appropriate photoconductor charging potential even when the photoconductor heating heater is removed and constant temperature of the drum is removed in an apparatus using an amorphous silicon drum. The purpose is to obtain an image.

[0009]

In order to solve the above problems, the present invention has a means for detecting the temperature of a photoconductor in an electrophotographic system using an amorphous silicon photoconductor, and the photoconductor is controlled by the temperature. The charging potential and / or the developing bias of (1) are controlled.

[0010]

Embodiments of the present invention will be described below.

In the present invention, attention is paid to the fact that the amorphous silicon photoconductor has a surface temperature dependency, and the charging voltage and the developing bias are controlled according to the change of the charging potential due to the temperature dependency.

FIG. 1 is an explanatory view for explaining the charging control method of the present invention.

Reference numeral 1 denotes an amorphous silicon drum, which rotates in the direction of the arrow. Reference numeral 2 denotes a charging scoroton charger, and a voltage is applied to the wire 3 from a power supply 15. The shield case 4 and the grid 5 are grounded via the Zener diode 6. The zener diode 6 determines the potentials of the grid 5 and the shield case 4. Reference numeral 7 is a light irradiation means for forming an electrostatic latent image such as a laser or an LED. Reference numeral 8 denotes a developing means, and a developing sleeve 9 carrying a toner for forming a toner image faces the photoconductor 1. A developing bias is applied to the developing sleeve 9. Reference numeral 10 denotes a transfer unit such as a transfer roller for transferring the toner image on the photoconductor 1 onto the recording medium 11. A cleaning unit 12 removes the residual toner on the photoconductor 1 with a blade or the like. 13
Is a temperature detecting means for detecting the temperature on or near the surface of the photoconductor 1, and detects the temperature on or near the surface of the photoconductor 1.
The control circuit 14 controls the power supply 15 that supplies the scorotron current based on the detected temperature information, and performs current control corresponding to the temperature of the photoconductor 1. Similarly, the power supply 16 controls the developing bias applied to the sleeve 9 of the developing means 8 according to the temperature detected by the temperature detecting means 13.
Is controlled by the control circuit 14.

As described above, according to the present invention, the temperature detecting means 13 detects the temperature on or near the surface of the amorphous silicon photoconductor.
The charging and developing conditions can be controlled in accordance with the characteristics of the photosensitive member that are detected by the method described above and that change depending on the temperature. Therefore, stable image formation can be performed without depending on the environmental temperature.

[0015]

Embodiments of the present invention will be described below.

LS-6500 made by Kyocera, which is an LED printer using an amorphous silicon drum as an evaluation machine.
In the printer, the drum heater was removed, various control programs were modified, and the printer was modified to operate normally without the drum heater.

A scorotron charger as shown in FIG. 1 was used as a charging device, and the potentials of the grid and the shield case were fixed at 400 V by a Zener diode. For charging control, the surface temperature of the drum is detected and the scorotron current value Ic of the charger is controlled based on this data. The value of the charging potential at each temperature is shown in FIG.

FIG. 2 shows the dependence of the charging potential on the environment, and it can be seen that the charging potential is stable at 300 V even when the environmental temperature changes.

[0019]

As described above, according to the present invention, a stable charging potential can be maintained by controlling the control voltage or current of the charging or developing bias even when the environmental temperature changes.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining a charging control method of the present invention.

FIG. 2 is a diagram showing changes in the value of a charging potential at each temperature.

FIG. 3 is a diagram in which the surface potential of the photosensitive member is plotted against the surface temperature of the photosensitive member.

[Explanation of symbols]

 1 Photoconductor 2 Scoroton Charger 3 Wire 4 Shield Case 5 Grid 6 Zener Diode 7 Light Irradiating Means 8 Developing Means 9 Developing Sleeve 10 Transfer Means 11 Recording Medium 12 Cleaning Means 13 Temperature Detecting Means 14 Control Circuit 15 Power Supply

Claims (3)

[Claims] 1. An electrophotographic system using an amorphous silicon photoconductor, comprising means for detecting the temperature of the photoconductor, and controlling the charging potential and / or developing bias of the photoconductor by the temperature. And an electrophotographic device. 2. The electrophotographic apparatus according to claim 1, wherein the temperature of the photoconductor is detected and the DC component voltage or current of the power source of the charger is controlled based on the temperature. 3. The electrophotographic apparatus according to claim 1, wherein the temperature of the photoconductor is detected and the DC component voltage or current of the power source of the developing device is controlled based on the temperature.