JPS63159881A - Electrostatic discharging device - Google Patents

Abstract

PURPOSE:To stabilize control in any environment and to perform uniform electrostatic charging and discharging by controlling a bias voltage between the bare electrode of an electrostatic discharging device and a member to be charged electrostatically by a control means within a predetermined range, and controlling an applied alternating voltage or its frequency when the bias voltage exceeds the control range. CONSTITUTION:Two buried electrodes 11 and 12 are buried in the electrostatic discharging member 1' of the electrostatic discharging device 1 and the bare electrode 13 is provided on the surface of a dielectric 10. Those electrodes 11 and 12 are applied with the voltage of an AC power source 14 to initiate electrostatic discharging. Then the electrode 13 is applied with the bias voltage which extracts ions generated by the electrostatic discharging toward the member 2 to be charged electrostatically. A detection part 20 which detects electrostatic charging and discharging currents flowing to the member 2 is provided between the electrode 13 and ground. A control circuit 21 is connected to the output side of this detection part 20 and the charging and discharging currents are controlled by the circuit 21 to preset values according to the output of the detection part 20. When the current exceeds the control range, the voltage or frequency of the power source 14 which applies the voltage to the electrodes 11 and 12 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is utilized in the field of discharge technology, and particularly relates to a discharge device for charging and neutralizing photoreceptors of electrophotographic copying machines.

(Prior art) This type of discharge device generates positive and negative ions by applying an alternating current voltage between electrodes that sandwich a dielectric material, and causing the discharge near one electrode. A charging device extracts ions of a predetermined polarity among these ions toward the charged member by an electric field formed by a bias voltage applied between the one electrode and the charged member, and makes them adhere to the charged member. or is known, for example as shown in US Pat. No. 4,155,093.

In this method, the electrodes where the discharge occurs are exposed;
Since the discharge occurs strongly near this exposed electrode,
The electrode is easily corroded by plasma etching, oxidation, etc. caused by discharge. When such corrosion occurs, the discharge becomes uneven, resulting in uneven charge removal and charging effects, which poses a problem in practical durability.

Therefore, with the aim of improving the above-mentioned durability, the applicant has
It has a dielectric material, at least two electrodes buried in the dielectric material, and an exposed electrode, and the buried electrode is capable of discharging the dielectric material at a predetermined discharge starting voltage when an alternating current voltage is applied between them. The exposed electrode is placed at a position where a discharge occurs near a part of the surface of the body, while the exposed electrode is located at or near a part of the surface and has a discharge starting voltage between it and any buried electrode. In Japanese Patent Application No. 61-18954, a discharge device was devised in which the discharge device was installed at a position higher than the predetermined discharge starting voltage.

According to the above-mentioned plan, the durability against electrode corrosion due to radiation is significantly improved.

(Problems to be Solved) However, when actually removing and charging electricity with this discharge device, the environment near the discharge electrode cannot be ignored in order to obtain uniform removal and charging. In other words, the discharge characteristics vary greatly depending on the surrounding environment (humidity, temperature, and atmospheric pressure), especially humidity, and it is difficult to maintain a uniform and stable discharge under relatively high humidity (e.g., relative humidity of 40% or more). Furthermore, in this discharge device, compared to other discharge devices such as corona discharge devices, the amount of ions generated increases significantly as the temperature rises, and the removal/charging current also increases accordingly. JJ Shita.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned particular problems, and includes at least two electrodes for alternate voltage application that are embedded in a dielectric material and that are exposed. a discharge member including an output electrode; a bias power supply that applies a bias voltage for applying ions to the charged member between the bare electrode and the charged member; and a detection unit that detects a current flowing through the charged member. means for controlling the h ri main current to a preset value;

- a control means for controlling the bias voltage within a predetermined range according to the current detected by the detection stage f; At a predetermined discharge starting voltage, the exposed electrode is placed at a position where a discharge occurs near a part of the surface of the A-heavy body, and the exposed electrode is located at or near a part of the surface, and is located at any buried The voltage for generating a discharge between the electrodes is also provided at a position higher than the predetermined discharge starting voltage, and a bias voltage is applied, and the control means controls when the bias voltage exceeds the control range. The present invention is characterized in that it is a control means that controls the current to a preset value by controlling the alternating voltage applied between the buried electrodes or the frequency of the alternating voltage.

(Example) Hereinafter, the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a sectional view of a discharge device according to an embodiment of the present invention.

The discharge device l of this embodiment includes at least two buried electrodes 11 and 12 buried in the dielectric IO and the dielectric 11.
] and has a bare electrode 13 provided on the surface. The two buried electrodes 1 and 12 are electrodes for applying heavy alternating current pressure to generate discharge, and the exposed electrode 13 extracts ions generated by discharge toward the charged member 2. This is the electrode to which a high-ass voltage is applied.

The electrodes 11 , 12 are connected to an AC power source 14 .

The voltage waveform applied between the electrodes 11 and 12 may be either a sine wave or a rectangular pulse waveform. In short, it is sufficient that the voltage is such that an alternating electric field is formed on the surface of the dielectric material.

The exposed electrode 13 is connected to a DC bias power supply 19. The bias voltage applied between the conductive base 18 and the bare electrode 13 of the member to be charged 2 is not limited to direct current, but may be alternating current biased so as to extract specific ions.

A detection unit 20 is provided between the bias power supply 19 and the earth as a detection means for detecting the neutralization/charging current flowing through the charged member 2 when the liquid gland/charging member 2 is neutralized or charged. The output of the detection section 20 is given to a control circuit 21 as a control means.

This control circuit 21 controls the removal/charging current to a preset value according to the output of the detection unit 20. In this embodiment, the above-mentioned bias is controlled according to the detected removal/charging current. This is done by controlling the bias voltage of the power supply 19 within a predetermined range, and if it exceeds the control range, the buried electrodes 11, 12
This is done by controlling the AC voltage of the AC power supply 14 applied between them.

The dielectric lO1 buried electrode It, 12 and exposed electrode 13 will be described in detail below, including their materials.

The dielectric IO is an inorganic electrically conductive material with high discharge resistance, such as glass, ceramic, oxides such as SiO□, MgO, and 81□03, or nitrides such as silicon nitride (SiJ4) and aluminum oxide (AIN). In this example, it is a long member with a rectangular cross section.

The electrodes 11.12 embedded in the dielectric IO are arranged in the figure parallel to the bottom surface of the dielectric (the surface facing the liquid gland/charging member 2) and equidistant therefrom. Although this is not essential, it is preferred for manufacturing reasons. The buried positions of the buried electrodes 11 and 12 are set at positions where a discharge occurs near a portion of the surface of the dielectric 10 at a predetermined discharge starting voltage when an alternating current voltage is applied between them. As the material for these electrodes, AI, (:r, Au, Ni, etc.) can be used.It should be noted here that in the end use, these electrodes are buried and not exposed, and corrosion does not occur. High durability can be maintained even when using materials such as those mentioned above.

The distance between buried electrodes should be 1k11 or more, considering dielectric strength.
However, it is particularly preferable that the thickness be 3 to 200 μm.

In the above description, the dielectric IO is an integral body, but it may be a two-layer dielectric that is joined at the upper surface or lower surface of the dielectric IO and/or the buried electrode 11. In this case, the materials of each layer may be the same or different. In particular, when the 7Aitt body layer is made of two layers, dielectric 10a and dielectric 10b, as shown in the figure, the dielectric layer where discharge occurs on the back side is made of an inorganic material with high discharge resistance to extend the life of the dielectric material. However, an organic dielectric may be used as the dielectric material on the opposite side. Regardless of whether it is a one-piece structure or a two-layer structure,
The thickness of the dielectric under the buried electrode is 1m or more, 500m
It is preferably 3 m or more and 2004 m or less, particularly 3 m or more and 2004 m or less.

In this embodiment, the bare electrode 13 is fixed to the bottom surface of the discharge device 1 in which discharge is generated by the alternating current voltage. This electrode 13
Examples of the material include conductive metals with high corrosion resistance and oxidation resistance, such as Ti, W, Cr, Te, Mo, Fe, Co,
High-melting point metals such as Ni, Au, and Pt, alloys containing these metals, or oxides are used. Its thickness is 0.1-100 μm, preferably 0.2-21
1g tri.

The width is at least 100 JL, preferably 10 to 500 JLIII. The position of the bare electrode is near the end of the discharge generation region 15, and the AC applied voltage that causes discharge to start between it and either of the buried electrodes (11 and 12) is higher than the predetermined discharge start voltage. Here, the vicinity of the discharge area includes the vicinity including the outside and inside thereof, and it is preferable to be outside, or even if it is inside, it is functionally satisfactory if it is near the end of the discharge area.

In this embodiment as described above, discharge is performed as follows. Note that the discharge device 1 of this embodiment can be used to neutralize or charge the liquid gland/charging member 2 consisting of the dielectric layer or photoreceptor layer 17 and the conductive substrate 18;
Since the principles of electrification removal and charging are the same, only the case where electrification is performed will be explained.

When an AC voltage higher than a predetermined discharge starting voltage is applied between the buried electrode 11 and the buried electrode 12 by the AC power supply 14, this causes the bottom surface of the illustrated discharge device 2t (same as the electrode 11 to which the AC voltage is applied) to be applied. 12)
Reference numeral 15 is centered on the portion facing the vicinity of the electrodes.
A discharge occurs in a single region shown by , and positive and negative ions are generated at an alternating voltage. However, since a bias voltage is applied to the exposed electrode 13 by the bias power supply 19, ions of a desired polarity among the ions are extracted toward the member to be charged 2, and the member to be charged 2 is not charged. Ru.

The electric field strength of the discharge region 15 is stronger toward the center and gradually becomes weaker toward the outside. The previous conventional one C is
Is the part corresponding to the center of the discharge area where the electric field strength is extremely strong the same as the end face of the conventional discharge electrode? Corresponds to the junction with the surface of the A-electrode, and a strong discharge attack can cause electrode deterioration (
In contrast, in the discharge device 1 shown in Fig. 1, alternating current discharge occurs between the surfaces of the dielectric, which causes deterioration of the dielectric. #There is almost no sound, and a stable AC discharge is connected for a long time, and the exposed electrode 13
By arranging the electrode near the discharge area 15 and applying a DC bias voltage between it and the conductive substrate 18 using the DC bias power supply 19, there is almost no deterioration or wear on the exposed end surface of the exposed electrode 1, and it can be used for a long period of time. Is it stable over time? iF'rt
(In addition, in the case of charge removal, an alternating current bias may be applied).

Furthermore, since the following control is performed, it is possible to perform uniform and stable charge removal and charging without being affected by environmental fluctuations such as temperature changes.

That is, as described above, the member 2 to be charged is charged by extraction of ions, but in this case, the current flowing through the member 2 is detected by the detection unit 20.

In Fig. 1, a direct current voltage is applied as a bias voltage to the bare electrode 13.
At this time, the charging current is detected by the current detection unit 20, and the bias voltage of the bias power supply 19 is adjusted by the control circuit 21 according to the detected charging current. The current value is controlled to be a preset value by changing the external electric field.

Furthermore, in this case, in this example, the second limit of the bias voltage is set, and if the set current is not reached even if the bias voltage is increased to this upper limit by the control circuit 21, then the AC voltage of the AC power supply 14 is increased. is controlled, and electrode 1 is controlled by changing the AC voltage.
The AC electric field applied between electrode 1 and electrode 12 is changed so that the current value becomes a preset value without further changing the external electric field (i.e., changing the bias voltage).

FIG. 2 shows an AC power source 14 used in the device shown in FIG.
, a block diagram of a specific example of the bias power supply 19, the detection section 20, and the control circuit 21 is shown.

The detection section 20 includes a current detection circuit 22, and the control circuit 21 includes a constant current control circuit 23. Further, the bias power supply 19 is connected to a PWM circuit (pulse width control circuit) 24 supplied with the output of the constant current control circuit 23.
, an inverter circuit 25 , and a rectifier circuit 26 , and the AC power supply 14 includes an AC oscillation circuit 27 , an AC amplifier circuit 28 controlled by the constant current control circuit 23 , and an AC
It has a C transformer 29.

In this configuration, the control circuit 14 controls the pulse width by the P-W-M circuit (pulse width control circuit) 24 inside the bias power supply 19 in accordance with the electric current detected by the current detection unit 13 to adjust the bias voltage. The output voltage of the source 19 is controlled by v so that the above current value becomes a predetermined value.

At this time, if a situation occurs in which a predetermined current value cannot be obtained even if the bias voltage reaches a certain limit value, the control circuit 14 further controls the AC amplifier circuit 28 inside the AC power supply 14. The output voltage of the AC power supply 14 is controlled to be the above-mentioned current value or a predetermined value.

In this way, the charging current is made to reach a preset value.

As a result, the external electric field can be controlled by changing the bias voltage, and the alternating current voltage can be controlled even if the discharge state due to environmental humidity changes and temperature changes near the exposed electrode, that is, changes in the amount of ions generated by the exposed electrode 13, can occur by changing the bias voltage. By controlling the AC electric field in the AC discharge region J5 described above by
It became possible to eliminate fluctuations in charging current.

FIG. 3 shows an example of a method for controlling the charging current of the discharge device 1 shown in FIG. 1 in response to, for example, temperature changes in the discharge member 1° comprising the electrodes 11, 12, the dielectric port 13, and the electrode 13.

As can be seen from FIG. 3, when a certain bias voltage is applied, for example, when the humidity of the discharge member l' changes, the charging current changes. This variation is detected and the bias voltage is controlled to maintain the set current. In this embodiment, even if this bias voltage reaches the upper limit value shown in the figure, if a situation occurs where the charging current is insufficient for the planting, next, the AC voltage is controlled,
The discharge state of the discharge region 15 is changed to increase the amount of ions generated near the bare electrode, thereby replenishing the shortage of charging current.

By performing such control, due to some reason (for example, if the discharge area 15 is extremely reduced due to the adhesion of a resistive substance to the dielectric surface), the charging current will be drastically reduced, and the bias voltage will become abnormal. Not only can it be used to prevent abnormal discharge from occurring between the bare electrode and the charged member, but even under such circumstances,
By changing the discharge state by controlling the AC voltage, it is possible to stabilize the charging.

Fig. 3 shows, as an example, a method of controlling temperature changes in the discharge member l゛; The discharge device of the present invention has the effect of stabilizing charging against all factors such as fluctuations in current in band i due to changes in characteristics of members.

Furthermore, compared to controlling the AC voltage, controlling the bias voltage can vary the amount of ions applied to the liquid glands/charging member 2 by a large 11%, and at the same time, a large increase in the AC voltage is caused by dielectric This will significantly increase the electric field strength in the discharge region 15 on the body surface, resulting in FA71! 1h in which the bias voltage is fixed and the neutralizing and charging current flowing through the fluid gland/charging member 2 is controlled by controlling only the alternating current voltage is not desirable because it shortens the durability of the body 10. Discharge device 711 in FIG.
Since the bias voltage is controlled, it is possible to prevent the disadvantage of shortening the durability of the dielectric IO, and it is also possible to vary the amount of ions attached over a wide range.

Furthermore, of course, making the charging current constant is not limited to the above-mentioned specific example, but basically involves the following mechanism: detecting the charging current, changing the external electric field depending on its value, and achieving a predetermined charging current. It is sufficient to have a mechanism that sets the current to a predetermined current value, and then changes the discharge shape IE of the discharge region 15 when a certain external electric field is reached and sets the current value to a predetermined value.

For example, instead of controlling the ti of the alternating current voltage, the above-mentioned effect can be obtained by changing the frequency of the alternating voltage. Here, the control of the frequency of the AC voltage is to change the discharge state by changing the number of discharges in the discharge region 15 described above, and by changing the discharge state in this way, the stabilization of charging can be achieved by 1λl. You can. Note that such a constant current control method is unique to the discharge device having this configuration, and is fundamentally different from the constant current control method by controlling the corona discharge voltage in conventional corona discharge devices.

(Effects of the Invention) As explained below, according to the device of the present invention, in order to control the current flowing through the member to be charged to a preset value, the naked output is detected in accordance with the current detected by the detection means. Control the bias voltage between the electrode and the charged member within a predetermined range, and if the bias voltage exceeds the limit u4wa range, control the alternating voltage applied between the buried electrodes or its frequency. Therefore, it is possible to perform stable and uniform charge removal and charging under any environment.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a specific example of the bias power supply, AC power supply, detection section, and control circuit shown in FIG. 1. FIG. 3 is a characteristic diagram for explaining a control example according to the invention. l・・・・・・・・・・・・Discharge device l°...
・・・・・・・・・Discharge member IO・・・・・・・
・・・・・・・・・Dielectric 11.12・・・・・・・・・
Buried electrode 13...Exposed electrode 19...Bias power supply 20
.........Detection means (detection section) 2
1・・・・・・・・・・・・・・・Control means (control circuit) Patent applicant Canon Co., Ltd. Agent
Patent Attorney Fujioka Shoji Figure 1 Figure 3 Bias voltage

Claims (1)

[Scope of Claims] A discharge member in which at least two electrodes for applying voltage alternately are buried in a dielectric material and also includes an exposed electrode, and a bias voltage for applying ions to a charged member is applied to the exposed electrode. a bias power source applied between the charged member and the charged member; a detection means for detecting the current flowing through the charged member; and a detecting means for detecting the current flowing through the charged member; and a control means for controlling the bias voltage within a predetermined range according to the buried electrode, and the buried electrode has a control means for controlling the bias voltage within a predetermined range, and the buried electrode has a predetermined discharge starting voltage when an alternating voltage is applied between them. The bare electrode is placed at a position where a discharge occurs near a part of the surface, and the exposed electrode is located at or near a part of the surface, and the voltage for causing a discharge between it and any of the buried electrodes is above the level above. The control means is provided at a position higher than a predetermined discharge starting voltage and applies a bias voltage, and when the bias voltage exceeds the control range, the control means controls the alternating voltage applied between the buried electrodes or the frequency of the alternating voltage. A discharge device characterized in that it is a control means that controls the current to a preset value by controlling the current.