JPS63129364A - Discharging device - Google Patents

Abstract

PURPOSE:To uniformly and stably discharge under any circumstances and conditions by providing at least the discharge part of the surface of a dielectric with a means preventing a drop in the surface resistance of the dielectric on the side of a bare electrode. CONSTITUTION:The titled device has at least two buried electrodes 11 and 12 buried in the dielectric and the bare electrode 13 provided on the surface of the dielectric 10. Independent of the dielectric 10, a wind lead device is provided which brings an heated or dried air flow 20 to the discharge part of the dielectric 10. Hence the air heated or dried by a heater 21 is sent to a wind lead path 23, and it is fed toward the surface of the dielectric on the side of the bare electrode 13. Thus a drop in the surface resistance of the dielectric is prevented, whereby a uniform and stable discharge is attainable.

Description

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

(Prior Art) This type of discharge device applies an alternating current voltage between electrodes disposed to sandwich a dielectric material to generate a discharge near one electrode to generate positive and negative ions. A charging device extracts ions of a predetermined polarity among the 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, It is known, for example, as shown in US Pat. No. 4,155,093.

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

Therefore, in order to improve 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 electrodes react to 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.

With the above-mentioned proposal, the durability against electrode corrosion due to electric discharge has been significantly improved.

(Problems to be Solved) However, the discharge device using this method has a problem unique to this discharge method that is different from the corona discharge device. Adhesion of charged particles, which is a serious problem in corona dischargers, is hardly a problem with this method, and even some adhesion has almost no effect on the alternating current discharge, and a uniform and stable discharge is always possible. Warm, however.

Adhesion of substances that reduce the surface resistance of the dielectric surface where AC discharge occurs, such as adhesion (adsorption) of moisture in the air in high humidity, or discharge products, such as
The adhesion of low-resistance substances such as ammonia and nitric acid slightly lowers the surface resistance of the dielectric surface, and as a result, the alternating current discharge on the dielectric surface becomes extremely unstable in the low-resistance area, and the discharge becomes uneven. A problem arose in that it caused

Therefore, the present applicant has further developed a discharge device in which a heating element is embedded in the dielectric material or is formed in direct contact with the outer surface of the dielectric material according to the above-mentioned proposal. , in this one, the heating element is placed in the dielectric body,
For example, burying a resistance heating element, depositing it on the surface of a dielectric material,
It may be necessary to form them in direct contact with each other by etching or the like, and such special treatment may be required for the inducer according to the above-mentioned proposal.

(Means for Solving the Problems) The present invention has been made in view of the above points, and the discharge device of the present invention includes a dielectric body in which at least two electrodes for applying an AC voltage are embedded. An exposed electrode for applying a bias voltage is provided on the exposed electrode, and a means for preventing a decrease in surface resistance of the dielectric surface on the side of the exposed electrode is provided on at least the discharge portion of the dielectric surface.

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

FIG. 1 is a sectional view of a first embodiment of the discharge device of the present invention.

The discharge device l of this embodiment includes at least two buried electrodes 11 and 12 buried in the dielectric 10, and
It has a bare electrode 13 provided on the surface of the electrode. The two buried electrodes 11 and 12 are electrodes for applying an alternating current voltage to generate a discharge, and the one exposed electrode is a bias voltage for extracting ions generated by the discharge toward the charged member 2. This is an electrode to which a voltage is applied.

Further, separate from the dielectric IO, an air guide device is provided to bring a stream of heated or dry air 20 to the discharge portion of the dielectric IO, as a means for preventing a decrease in the surface resistance of the surface of the dielectric 10. There is. In this embodiment, the air guide device includes a heater 21 and an air guide path 23. The heater 21 is connected to a heating power source 22 and is surrounded by an air guide path 23, the outlet of which extends to the surface of the dielectric 10 and is directed toward the discharge portion.

The dielectric 10, buried electrodes 11, 12, and bare electrodes 13 will be described in detail below, including their materials.

The dielectric 10 is made of a non-411 dielectric material with high discharge resistance, such as glass, ceramic, etc. 5i02. MgO,AI□03
It is made of an oxide such as silicon nitride (SiJJ) or a nitride such as aluminum nitride (AIN), and in this embodiment, it is a long member with a rectangular cross section.

The electrodes 11, 12 embedded in the dielectric IO are arranged parallel to the bottom surface of the dielectric (facing the fluid gland/charging member 2) and equidistant therefrom. Although this is not essential, it is preferred for manufacturing purposes. The buried positions of the buried electrodes 11 and 12 are set at positions where, when an alternating current voltage is applied between them, a discharge occurs near a part of the surface of the dielectric IO at a predetermined discharge starting voltage. As materials for these electrodes, AI, Cr, Au, Ni, etc. can be used. What should be noted here is that in the present invention, these electrodes are buried and not exposed, and corrosion does not occur, so that high durability can be maintained even when the above materials are used.

The distance between buried electrodes should be 1 μm or more, taking into account dielectric strength.
In particular, it is preferably 3 to 200 μl.

The dielectric 10 may be a single piece in the above description, or it may be a two-layer dielectric joined at the upper surface or lower surface of the dielectric 10 and/or the buried electrode 11. In this case, the materials of each layer may be the same or different. In particular, when the dielectric layer is made of two layers, the first dielectric 10a and the second dielectric tab, 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 ensure the life of the dielectric material, a molar dielectric may be used as the dielectric material on the opposite side. In either case of integral structure or two-layer structure, the thickness of the dielectric material under the buried electrode is 1ILI11 or more and 500 fiLrn or less, especially 3JL11 or more20
0 gm or less is preferable. In this embodiment, the bare electrode 13 is fixed to the bottom surface of the discharge device 1 where discharge by the alternating current voltage occurs. A temperature increasing power source 20 is connected to the bare electrode 13. The material of this electrode 13 may be a conductive metal with high corrosion resistance and oxidation resistance, such as Ti, W, or Cr.
, Te.

High-melting point metals such as Mo, Fe, Co, Ni, Au, and Pt, alloys containing these metals, or oxides are used. Its thickness is from 0.1 to 1004 ff+, preferably from 0.2 to 20 I, and its width is at least 1 m, preferably from 10 to 500 gtn. The position of the bare electrode is near the end of the discharge generation region 15, and the AC applied voltage that causes discharge initiation between it and any of the buried electrodes (11 and 12) is higher than the predetermined discharge initiation voltage. It's the location. Here, the vicinity of the discharge area refers to the vicinity including the outside and the inside thereof, and the outside is preferable, but even if it is inside, it is functionally satisfactory as long as it is near the end of the discharge area.

In this particular embodiment 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 )
Reference numeral 15 is centered on the portion facing the vicinity of the electrodes.
A discharge occurs in a single region shown as , and positive and negative ions are generated alternately. 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.

Note that the polarity of the extracted ions is determined by the polarity of the applied bias voltage.

At the same time, air heated or dried by the heater 21 is sent into the air guide path 23, and is sent out toward the dielectric surface on the exposed electrode 13 side.
This prevents the surface resistance of the dielectric from becoming low, and allows uniform and stable discharge to occur at all times.

Here, the relationship between the surface resistance of the dielectric surface and the discharge state is as follows, for example.

The following Table 1 shows SiO as a dielectric material by sputter method.
20 pieces of 21A
The results of observing the discharge state and charging unevenness when changing the surface resistance in the discharge device manufactured with the configuration shown in the figure are shown.

In Table 1 above, the mark [○] indicates a uniform discharge state and the charging unevenness is within ±10%, and the mark [△] indicates whether the discharge state looks uniform or the charging unevenness is within the range of ±10% to 20%. The [x] mark above, which is beginning to be observed as charging unevenness, indicates that the discharge state is clearly non-uniform and the charging unevenness is also significant.

From Table 1, it can be seen that by maintaining the surface resistivity of the dielectric at 109[01 or more, preferably IQIO[01 or more], stable and uniform charge removal is always possible in the discharge device of this method.

Therefore, in conditions where the surface resistance is likely to decrease, such as when used in high humidity, it is sufficient to maintain the dielectric surface at a high resistance.

The following Table 2 shows, for example, temperature 300C1 relative humidity 90%
This example shows that it is possible to eliminate the discharge unevenness peculiar to the discharge device (Fig. 1) and to enable uniform discharge on the dielectric surface even under the environment of the discharge device (Fig. 1).
This indicates that it is sufficient to raise at least the surface temperature of the dielectric 10b to 38°C or more, preferably 40'C or more.

(Environment: 30℃, 90% (relative humidity))
According to the example shown in the figure, not only the adhesion of moisture in high humidity conditions, but also the adhesion of low-resistance discharge products (ammonia, nitric acid, etc.) on the dielectric surface as shown in Table 2 above. Due to the phenomenon of adhesion (adsorption) moisture content due to temperature rise,
It becomes possible to suppress a significant decrease in surface resistance, and it becomes possible to maintain uniform discharge even under the above conditions.

In this way, in this embodiment, the air flow 20 sent out as described above prevents low resistance and enables uniform and stable discharge, and also directly raises the temperature of the dielectric surface to lower the resistance. Instead, the surface resistance of the dielectric 10b is prevented from decreasing by increasing the temperature or by using the dry air flow 20, so there is no need for special processing such as embedding a heating element in the dielectric 10. In most cases, there is no need to change the structure or manufacturing method of the dielectric IO.

Note that the figure shows the case where the air is heated or dried by the heating heater 22, but any means that generates a heated or dry air flow may be used.

The second embodiment shown in FIG. 2 is an example in which an insulating material 24 is attached to the surface of the dielectric 10b as a surface resistance prevention means that is less susceptible to the effects of environments such as high humidity, and the surface is coated. For example, by applying a slightly thin layer (for example, a thickness of Igm or less) to the surface of silicone oil, it is possible to significantly prevent a decrease in surface resistance in high humidity, and to always achieve uniform and stable discharge.

The advantage of this method is that by rubbing with felt or the like containing silicone oil, a uniform coating can be formed on the surface and the discharge can be stabilized.

(Effects of the Invention) As described above, according to the device of the present invention, it is possible to prevent a decrease in the surface resistance of the dielectric surface of a structure in which at least two electrodes are buried and exposed electrodes are provided, so that it is possible to It is possible to perform a uniform and stable discharge even under the following conditions, and this can be done by heating the dielectric surface, drying air flow, or applying an insulating material. The effect can be achieved easily by using the body as it is.

[Brief explanation of the drawing]

The drawings are all schematic sectional views showing apparatuses according to embodiments of the present invention, and FIG. 1 shows a first embodiment, and FIG. 2 shows a second embodiment. I...Discharge device IO...Dielectric 11.12...Embedded electrode 13... ...Bare electrode 21.23...
...Surface resistance reduction prevention means (air guide device) 21...
......Heating heater 23...
... Air guide path 24 ...... Surface resistance reduction prevention means (
Insulating material) @Figure 1

Claims (3)

[Claims] (1) A bare electrode for applying a bias voltage is provided on a dielectric body in which at least two electrodes for applying an AC voltage are embedded, and the means for preventing a decrease in the surface resistance of the surface of the dielectric body on the side of the exposed electrode is provided as described above. A discharge device provided at least in a discharge portion of a dielectric surface. (2) The means for preventing a decrease in surface resistance is an air guide device that guides a heated or dry air flow through an air guide path to at least the discharge portion of the dielectric surface. (1) The discharge device described in paragraph (1). (3) The surface resistance reduction prevention means is an insulating material thinly applied to at least the discharge portion of the dielectric surface. The discharge device according to claim (1), characterized in that: