JPH0247676A - Electrostatic charging device for electrophotographic image forming device - Google Patents

Abstract

PURPOSE:To remove the influence of the fatigue of a photosensitive body due to repetitive use and an environmental change by correcting the electrostatic charging capacity of an electrostatic charger according to a potential which is induced by charging an electrode part electrostatically by the electrostatic charger by using equivalent circuits of the photosensitive body. CONSTITUTION:In the preprocess of the electrostatic charging of the photosensitive body 3, the electrostatic charger 1 is made to operate on the electrode part 4a to which equivalent circuits 4c-4f of the photosensitive body 3 are connected, the electrostatic charging capacity of the electrostatic charger 1 is adjusted according to the potential induced at the electrode part 4a, and the photosensitive body 3 is charged electrostatically with the adjusted electrostatic charging capacity. Then the equivalent circuits 4c-4f are switched according to, for example, the frequency of the repetitive use of the photosensitive body 3. Consequently, the influence of the fatigue of optical attenuation characteristics, etc., due to the repetitive use of the photosensitive body 3 and the environment in electrostatic charging operation is removed and a stable surface potential is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a charging device in an electrophotographic image forming apparatus, and particularly to adjusting the surface charging potential of a photoreceptor.

Conventionally, in an electrophotographic image forming apparatus, the voltage applied to the grid of a charger, for example, a scorotron charger, is switched depending on the number of times the photoreceptor is used and environmental conditions. To control the surface charging potential, or to adjust the surface potential by applying light to the photoconductor while detecting the surface potential of the photoconductor after charging the photoconductor to a high surface potential, for example, (Refer to Publication No. 669).

[Problems to be Solved by the Invention] However, with the method of switching the voltage applied to the grid of a scorotron charger, it is difficult to accurately determine the appropriate surface potential due to the time lag until the environmental conditions of the detector and charger become the same. Difficult to obtain well.

In addition, in the case of a color image forming apparatus, the method of adjusting the surface potential by applying light to the photoreceptor after charging the photoreceptor to a higher surface potential involves a series of multiple steps such as charging, exposure, development, and static elimination. Depending on the image being formed, fatigue (deterioration of light attenuation characteristics, etc.) may be concentrated on a specific part of the photoreceptor, and the detection range of the surface potential detector matches the fatigue concentrated part. When this happens, there are problems in that the photoreceptor cannot be uniformly charged, or that a surface potential detection device, a light source, etc. are required, resulting in high costs.

The present invention solves the above-mentioned problems, and provides a highly economical charging method that eliminates fatigue and environmental influences on the photoreceptor, stably charges the photoreceptor to an appropriate surface potential. The purpose is to provide equipment.

[Means for Solving the Problems] The present invention provides a method in which a photoconductive film is formed on a conductive support,
It has a photoreceptor that is used repeatedly and a charger that charges the photoreceptor, and an image exposure bag is placed on the charged photoreceptor! A charging device in an electrophotographic image forming apparatus that exposes to light to form an electrostatic latent image includes an electrode portion formed of a conductive member and disposed at a pre-process position for charging the photoreceptor; and an opposing t[i located opposite to the electrode section, which is electrically equivalent to the photoreceptor, and charging according to the potential induced in the electrode section by the charger. The device is equipped with a control section that adjusts the charging capacity of the device. Further, the charging device has a plurality of types of equivalent circuits, and is configured to switch the equivalent circuits according to the number of times the photoreceptor is repeatedly used.

[Function] In the above configuration, in the process before charging the photoconductor, a charger is operated on the electrode section to which a circuit equivalent to the photoconductor is connected, and charging is performed according to the potential induced in the electrode section. The charging capacity of the device is adjusted, and the photoconductor is charged using this adjusted charging capacity.With this adjustment, fatigue such as light attenuation characteristics due to repeated use of the photoconductor and environmental influences during charging operation are eliminated. A stable surface potential can be obtained.

[Embodiment] Hereinafter, the structure and operation of an embodiment of the charging device of the present invention will be described with reference to the drawings.

In this embodiment, a scorotron charger 1 is used,
The charger 1 is disposed at a slight interval so as to face a photoreceptor 3 made of a photoconductive film formed on a counter electrode 2 that is moved in the direction of arrow a during an image forming operation! has been done. Also,
An electrode portion 4a made of a conductive member is provided at a position upstream of the photoreceptor 3 in the direction of movement thereof. In this way, the electrode portion 4a is disposed at a position prior to the charging of the photoreceptor 3 by the charger 1.

The photoreceptor 3 has a conductive support 3b interposed between the photoconductive coating 3a and the counter electrode 2, and the electrode portion 4
An insulating member 4b is interposed between a and the counter electrode 2. Further, the counter electrode 2 is grounded.

The charger 1 includes a corona electrode 1a and a grid electrode 1b.
, a shield 1c, and an insulating support 1d for stretching and supporting the corona electrode 1a and the grid electrode 1b.The corona electrode 1a is connected to the corona discharge power source 1e, and the grid electrode 1b is connected to the grid power source. 1f, and the shield IC is grounded.

Corona discharge is performed by applying a high voltage between the corona electrode 1a, the shield lc, and the counter electrode 2 by the corona discharge power source 1e. t.

In addition, by applying the output of the grid power source 1f to the grid electrode 1b, the corona t, pole 1a and counter electrode 2
Alternatively, the current flowing to the photoconductive film 3a or the electrode portion 4a can be controlled.

Between the electrode portion 4a and the counter electrode 2, there is a first electrode which is equivalent to the photoreceptor 3 in terms of electric circuit. Second. Third. Fourth equivalent circuit 4c
, 4d, 4e, and 4f are connected via an equivalent circuit switch 4g. These equivalent circuits 4c to 4f are affected by the environment during charging in the same way as photosensitive #3, and are affected by fatigue that occurs depending on the number of times the photosensitive paper of the photoconductor 3 is used repeatedly (first to fourth times). The changes in photosensitive characteristics are taken into account and adapted accordingly. This can be determined by simulation.

Furthermore, an amplifier 5a that detects the potential induced in the electrode portion 4a, and a controller 5b that controls the equivalent circuit switch 4g, the corona discharge power source 1e, and the grid power source 1f using the output of the amplifier 5a are provided. It is being The controller 5b includes each equivalent circuit 4.
Regarding C to 4f, when the charger 1 is operated with the corona discharge power source 1e and the grid power source 1f set to predetermined outputs in an environment of specific temperature, humidity, atmospheric pressure, etc., it is detected by the amplifier 5a. The optimal potential induced in the electrode portion 4a is stored in advance as a target potential.

The photoconductive film 3a in the charging process is exposed to light by an exposure device not shown, so that an electrostatic latent image is formed on the photoconductive film 3a.

In the above configuration, first, 1 of the photoconductive wave InI3a
When used for the second time, the corona discharge power source 1e and the grid power source 1f are connected with the first equivalent circuit 4C connected.
The charger 1 is operated with an output of
In the pre-charging process, the electrode portion 4a is charged.

The surface potential induced in the electrode section 4a at that time is measured by an amplifier 5.
It is detected at point a and given to the controller 5b. The controller 5b compares the potential with a stored target potential, and adjusts the charging capacity of the charger 1, that is, the corona discharge power source 1e and the grid power source, so that this difference is at least zero. Adjust the output of 1f. After this adjustment, the charger 1 charges the photoconductive wave 1113a.

When using the photoconductive wave 1i3a for the second time or later, the second and subsequent equivalent circuits 4 are switched by the equivalent circuit switch 4g.
The same operation as above is performed with each of the terminals d connected.

In this way, it is possible to eliminate the optical attenuation characteristics caused by repeated use of the photoconductive film 3a and the influence of the environment, and it is possible to charge the photoconductive film 3a with a stable surface potential.

In particular, in the case of color image formation, since exposure is performed at least three times (Y, M, C), charging is also performed three times, which results in cumulative fatigue of the photoconductive film. By switching and using a plurality of different equivalent circuits, the photoconductive film can always be uniformly charged.

Although four equivalent circuits are used in the above embodiment, the present invention is not limited to this, and only one or two or more equivalent circuits may be used.

[Effects of the Invention] As described above, according to the present invention, an equivalent circuit of the photoconductor is used in the pre-process of applying IF electricity to the photoconductor, taking into consideration the degree of fatigue such as light attenuation characteristics due to repeated use of the photoconductor. hand,
The electrode section is charged with a charger, and the charging ability of the charger is corrected according to the potential induced thereby, making it possible to eliminate fatigue caused by repeated use of the photoreceptor and the effects of environmental changes. Therefore, an appropriate surface potential can be stably applied to the photoreceptor.

[Brief explanation of the drawing]

The drawing is a configuration diagram of an embodiment of a charging device in an electrophotographic image forming apparatus of the present invention. 1... Charger, 1e... Corona discharge power supply, 1f.
... Grid power source, 2... Counter electrode, 3... Photoreceptor, 3a... Photoconductive coating, 4a... Electrode portion, 4c
+4ci. 4e, 4f...Equivalent circuit, 5b...Controller (
control unit).

Claims (2)

[Claims] (1) A photoconductive film is formed on a conductive support and includes a photoconductor that is used repeatedly and a charger that charges the photoconductor, and the charged photoconductor is exposed to light by an image exposure device. A charging device in an electrophotographic image forming apparatus that forms an electrostatic latent image includes: an electrode portion formed of a conductive member and disposed at a position before charging the photoreceptor; An equivalent circuit that is electrically equivalent to the photoreceptor, connected between the electrode portion and a counter electrode located opposite to the electrode portion, and a charging ability of the charger according to the potential induced in the electrode portion by the charger. 1. A charging device for an electrophotographic image forming apparatus, comprising: a control section for adjusting the charging device. (2) The charging device in an electrophotographic image forming apparatus according to claim 1, wherein the charging device has a plurality of types of equivalent circuits, and is configured to switch the equivalent circuits depending on the number of times the photoreceptor is repeatedly used.