JPH10241827A - Corona discharge generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform uniform corona discharge processing without generating a spark even if a high voltage is applied, a distance between electrodes is shortened, and a dielectric is thinned by a discharge electrode consisting of a terminal part that does hot have a discharge part and a protrusion. SOLUTION: Specifically, a terminal part has its spherical or semi-spherical shape or the like. When a terminal part is spherical, a discharge part 2 can have a wire-shaped, knife-shaped, rod-shaped shape or the like used conventionally. A radius of the terminal part 1 is preferably large from the viewpoint of scattering of an electric field, and specifically 5mm or more. In corona discharge generation, rare gas such as air, oxygen, or helium is preferably blown from an upper part of a discharge electrode to a corona discharge area. A voltage to be applied between the discharge electrode and an opposite electrode is a pulse high-frequency voltage of 10 to 300kV in wave-height value, 20pps or more in repetition frequency, and 0.1 microsecond or more in Pal width, and a distance between electrodes is 30mm or less, and an average electric field strength is 30kV/cm or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge generating device which is less likely to generate a spark.

[0002]

2. Description of the Related Art Conventionally, a corona discharge treatment method is often used for modifying the surface of plastic, cloth, or the like. In the corona discharge treatment, it is preferable to perform a uniform corona discharge with uniform electric field strength in order to uniformly treat the material to be treated, and
In order to increase the processing efficiency, attempts have been made to increase the applied voltage, reduce the distance between the electrodes, and reduce the thickness of the dielectric.

However, the shape of a discharge electrode conventionally used for corona discharge treatment is simply a wire shape, a knife shape, a thin round bar shape or the like from the viewpoint of corona discharge easiness, and protrusions are present at both ends. Therefore, if the applied voltage is increased as described above in order to improve efficiency, the distance between the electrodes is reduced, or the dielectric thickness is reduced, spark discharge occurs between the electrodes, particularly at the end of the discharge electrode having a sharp protrusion. Because the concentration of the electric field occurs more remarkably, a strong corona discharge occurs, the spark reaches the dielectric surface, further extends along the dielectric surface, and eventually reaches the counter electrode and the housing ground that supports them. In addition, uniform corona discharge treatment cannot be efficiently performed on the material to be treated. On the other hand, it has been considered to prevent the spark by increasing the thickness of the Teflon dielectric, but this causes a problem that the above-described discharge efficiency is significantly reduced.

[0004]

SUMMARY OF THE INVENTION The present invention provides an efficient and uniform corona discharge without sparking even when a high voltage is applied, the distance between the electrodes is reduced, or the dielectric is made thinner. An object of the present invention is to provide a corona discharge generator capable of performing a treatment.

[0005]

According to the present invention, there is provided a corona discharge generator comprising at least a discharge electrode and a counter electrode, wherein a high voltage is applied between both electrodes, wherein the discharge electrode comprises a discharge portion and a terminal portion, The present invention relates to a corona discharge generating device characterized in that the terminal has no projection.

The corona discharge generator of the present invention is characterized in that a terminal portion having no projection is provided at the terminal of the discharge electrode, thereby avoiding the concentration of an electric field at the terminal of the discharge electrode and applying a high voltage. It is possible to easily provide a corona discharge generating device in which spark does not occur.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, a "projection" refers to a part that protrudes partially, and specifically refers to a part where an electric field is concentrated. Therefore, "has no protrusion"
The term “rounded” means that the concentration of the electric field does not occur, and should not be construed as being limited to the spheres, hemispheres, pipes, and the like specifically listed in this specification.

The discharge electrode used in the present invention comprises a discharge portion and a terminal portion having no projection. Specifically, the terminal portion has a shape such as a spherical shape, a hemispherical shape, a capsule shape, or a donut-shaped ring shape formed of a pipe.

When the terminal portion is spherical, the discharge portion can take various shapes such as a wire shape, a knife shape and a rod shape which have been conventionally used. Specifically, the structure as shown in FIGS. 1 to 3 is adopted, in which FIGS. 1 (a), 2 (a) and 3 (a) show vertical cross sections of the discharge electrode passing through the axis of the discharge part. 1 (b), 2 (b) and 3 (b) are schematic perspective views of a discharge electrode viewed from an axial direction of a discharge portion (hereinafter simply referred to as an axial direction). (Referred to as a schematic perspective view). In this case, the radius of the terminal portion is preferably as large as possible from the viewpoint of electric field diffusion, specifically, 5 mm or more, more preferably 40 mm or more.
If this radius is less than 5 mm, sparks may occur due to application of a high voltage.

Also, the discharge portion is so arranged that the lowermost line of the discharge portion is in contact with the circle of the terminal portion on the counter electrode side in the axial sectional view.
Preferably, it is connected to a terminal. The axial length of the discharge part, for example, m, n, in FIGS.
The value of p is set in accordance with the size of the material to be processed, that is, slightly larger than the length of the material to be processed in the axial direction of the discharge portion, for example, 0.1 to 5.0 m, preferably 0.3 to 3 m. , And their lengths are independent of the shape of each discharge part.

When the terminal portion is hemispherical, the discharge portion has a pipe shape having a radius equal to the radius of the hemispherical terminal portion, and the discharge electrode as a whole has a capsule shape. In particular,
Take the configuration as shown in FIG.
4A shows an axial sectional view, and FIG. 4B shows a schematic perspective view in the axial direction. Also in this case, from the viewpoint of electric field diffusion, it is desirable that the radii of the terminal portion and the discharge portion are larger, preferably 15 mm or more, and more preferably 40 mm or more.

The axial length q of the discharge portion at this time is the same as that in the case where the terminal portion is spherical, for example, 0.1 to 0.5.
0 m, preferably 0.3 to 3 m.

When the terminal portion has a capsule-like shape composed of a hemisphere and a pipe-shaped portion having the same radius as the hemisphere, the discharge portion has various shapes such as a wire shape, a knife shape or a rod shape conventionally used. Can be taken. Specifically, for example, when the discharge part is wire-shaped and the number thereof is five, a configuration as shown in FIG. 5 is adopted, in which (a) is an axial direction passing through the axis of the discharge part. FIG. 3B is a cross-sectional view, and FIG. Also in these cases, the radius of the hemisphere and the pipe-shaped portion in the terminal portion is preferably larger from the viewpoint of electric field diffusion, specifically, 15 mm or more,
More preferably, it is more than 40 mm. This radius is 1
If the thickness is less than 5 mm, sparks may occur due to application of a high voltage. The axial length of the pipe-shaped portion is not particularly limited.

Further, the discharge portion is arranged such that the lowermost line of the discharge portion contacts the circle of the terminal portion on the counter electrode side in the axial sectional view.
Preferably, it is connected to a terminal. The axial length of the discharge part is, for example, 0.1 to 5.0 m, preferably 0.3 in accordance with the size of the material to be processed as described above.
３3 m, and their length is independent of the shape of the discharge part.

[0015] When the terminal portion comprises a spherical portion and a pipe-shaped portion, the discharge portion is a wire-shaped portion conventionally used,
It can take various shapes such as a knife shape or a bar shape. The radius of the pipe in the pipe shape is less than or equal to the radius of the sphere. Specifically, for example, a discharge electrode of the type shown in FIG. 13 (in this case, the discharge portion is a knife type) used in Example 2 described later. That is, a slit (8) is provided in the pipe-shaped portion, inside which the discharge portion (2) is connected to the spherical portion at both ends.

In this case as well, the radius of the spherical portion in the terminal portion is preferably as large as possible for the reasons described above.
mm or more, more preferably 40 mm or more. The pipe radius of the pipe-shaped portion in the terminal portion is not particularly limited as long as it is equal to or less than the spherical portion radius, but it is preferable that the pipe radius and the spherical portion have the same radius in terms of availability. The discharge portion is preferably connected to the spherical portion such that the lowermost line of the discharge portion contacts the circle of the spherical portion on the counter electrode side in the axial cross-sectional view. For the axial length of the discharge portion, according to the size of the material to be processed as described above, for example,
It is 0.1 to 5.0 m, preferably 0.3 to 3 m, and the axial length of the pipe-shaped portion is set accordingly. Further, these lengths are independent of the shape of the discharge portion.

When the end portion is a donut-shaped ring made of a pipe, the discharge portion is a conventionally used wire shape.
It can take various shapes such as a knife shape or a bar shape,
It may be planar. In the case of a flat shape, the flat surface may be a net shape or a flat shape. The donut-shaped ring includes not only a ring constituted by two circles when viewed from directly above but also a ring constituted by two polygons having rounded corners. Specifically, the terminal ring of the discharge electrode used in the present invention has, for example, a shape as shown in FIGS. 6 to 10, in which (a) shows the discharge electrode as viewed from the counter electrode side. (B) is a schematic perspective view of the discharge electrode when viewed from the axial direction when the discharge part is linear, and a schematic view of the discharge electrode when viewed from the side when the discharge part is planar. Is shown.

The larger the radius of the pipe is, the more preferable it is for the above-mentioned reason.
mm or more, more preferably 40 mm or more. When the discharge part is flat and mesh-shaped, it is possible to make the pipe radius smaller than when the discharge part is wire-shaped, knife-shaped or rod-shaped. Further, it is desirable that the two polygons forming the sketch when the discharge electrode terminal portion is viewed from directly above are rounded. This is because the electric field is diffused. Specifically, the radius of curvature of the curve when the terminal portion is viewed from directly above is 30 mm or more, preferably 80 mm
It is desirable that this is the case.

Specifically, when two polygons forming a sketch when the donut-shaped ring is viewed from directly above are, for example, a figure based on a square as shown in FIG. Is the radius of curvature as described above,
Further, the distances s and t between the two pairs of opposite sides are set so as to secure a discharge portion length set according to the size of the material to be processed. The discharge part length in the discharge electrode is, for the same reason as the discharge part length described above, for example, 0.1 to 5.0 m,
Preferably it is 0.3 to 3 m. It is desirable that the diameter u of the circular donut-shaped ring as shown in FIG. 9 is 30 mm or more, preferably 80 mm or more.

When the terminal portion has such a ring shape and the discharge portion is linear, one or more discharge portions may be used from the viewpoint of efficiency. The number is not particularly limited, and depends on the dimensions of the terminal portion. In view of the electric field diffusion, the number is set at least 0.5 cm or more in parallel in the sketch when viewed from the counter electrode side. Is preferred. FIG. 6 (c) is a schematic view of a discharge electrode when three discharge electrodes are used and three discharge electrodes are used and the discharge electrode is viewed from the discharge unit axial direction. When the discharge part is flat, the discharge part can specifically take the form of a net or a plate, and this plane is also shown in FIGS. 7 (a) and 8 (a) for the purpose of the present invention. It is preferable to make the corners of the polygon that matches the ring shape round as shown in FIG. It is not necessary to install these planar discharge portions so as to completely cover the terminal portion ring, and it is sufficient that the planar discharge portion is in contact with the terminal portion at several places. It is preferable that the size is smaller than the size of the shape drawn by the contact where the discharge section plane contacts the terminal section ring. If it is larger than that, a projection is formed, which may cause spark generation.

Further, the terminal portion and the discharge portion can have a curved shape according to the counter electrode. Any of the discharge electrodes described above can take a curved shape in accordance with the counter electrode.For example, when the counter electrode is in a roll shape, and the discharge electrode includes a ring-shaped terminal portion and a planar discharge portion, the terminal portion and As shown in FIG. 15, the discharge portion can take a shape curved along the circumference of the rolled counter electrode. FIG. 15A is a schematic view of the roll-shaped counter electrode 18 and the curved discharge electrode 19 when viewed from the side, and FIG. 15B is a schematic longitudinal sectional view of the curved discharge electrode. Other dimensions, such as a pipe radius when taking such a configuration, are the same as the above dimensions when not being used by being curved, but the discharge portion in the curved discharge electrode has a wire shape,
Regardless of the shape, such as a flat shape, it is necessary to maintain a uniform distance from the counter electrode. This is because if the discharge part is locally approaching the counter electrode, it will cause spark generation. By using the discharge electrode including the terminal portion and the discharge portion curved in accordance with the counter electrode as described above, the corona discharge treatment can be performed more efficiently.

As the material of the electrode portion and the terminal portion of the discharge electrode having the above-mentioned shape used in the device of the present invention, a conductor material conventionally used as an electrode can be used.
For example, stainless steel, iron, brass, copper, aluminum and the like can be mentioned.

As for the method of connecting the electrode part and the terminal part made of these materials and having the above-mentioned shape, any method conventionally used for metal connection unless a protrusion is formed for the purpose of the present invention. For example, welding, soldering, silver brazing, and the like can be used.

In the corona discharge generator of the present invention,
It is preferable to blow air, oxygen or a rare gas such as helium, neon, argon, krypton, xenon, or the like from above the discharge electrode to the corona discharge region. This allows
Corona discharge treatment can be performed effectively. In the apparatus of the present invention, in consideration of this point, it is preferable to use a wire-shaped or net-shaped discharge portion so as not to hinder the gas flow (see FIGS. 9C and 10C). Therefore,
When the discharge electrode has the above-mentioned capsule shape, it is disadvantageous in terms of efficiency for such a reason. However, as shown in FIG. 11, the inside of the discharge electrode is made hollow, and a slit (8) is formed on the counter electrode side of the discharge part. A supply port (9) is provided on the opposite side, and the gas flow is supplied to the supply port through a gas flow outlet (7), and corona discharge treatment is performed while blowing the gas flow from a slit to a corona discharge region. This eliminates this disadvantage. At this time, since the discharge efficiency may be reduced due to the provision of the slit, a net or a wire made of the above-described material used for the discharge unit and the terminal unit is used for the slit. In the case of a wire, it is preferable to dispose the wire in parallel to the axial direction of the discharge unit.

As the counter electrode in the apparatus of the present invention, the same counter electrode as in the prior art can be used. However, it is more preferable to eliminate the protrusion at the terminal for the same reason as the discharge electrode. From the viewpoint of processing efficiency, it is preferable that the counter electrode has a large installation area in which the material to be processed is easily installed. As the counter electrode material, the same material as the above-described discharge electrode material can be used.

Preferably, a dielectric is interposed between the counter electrode and the non-processed material. In this way, even when the applied voltage (peak value) is high and the average electric field strength is high, generation of harmful sparks can be further prevented. As the dielectric, a vinyl chloride resin, a Teflon resin, and other general dielectric materials can be arbitrarily used. Note that comparing the conventional corona discharge generator and the corona discharge generator of the present invention, if the discharge conditions are the same, the device of the present invention has a smaller thickness and length of the dielectric than the conventional device. be able to. The thickness of the dielectric used in the device of the present invention is 1 to 8 mm or more, and its length is sufficiently longer than the counter electrode. The position of the dielectric is not particularly limited, and can be installed at any position. When a relatively thin dielectric layer is formed on the surface of the counter electrode, it is preferable to use a plate material of 0.1 mm or more, preferably 1.6 mm or more, as the counter electrode in order to obtain sufficient mechanical strength and durability. A thin film or foil of a conductive material such as copper or aluminum formed on the back surface of the dielectric may be used as the counter electrode. In this case, it is preferable to increase the thickness of the dielectric, for example, to about 5 mm or more in order to provide mechanical strength. In order to perform the corona discharge treatment continuously and uniformly, the counter electrode and the dielectric can be formed on a drum and used while rotating so that the material to be treated can be transported at a constant speed.

In using the corona discharge generator of the present invention, the present invention is particularly useful when performing a corona discharge treatment by applying a high voltage, and is further effective when the distance between the electrodes is to be reduced. . Specifically, as the voltage applied between the discharge electrode and the counter electrode, the peak value is 10 to 30.
0 kV, preferably 40-200 kV, more preferably 5 kV
0 to 120 kV, repetition frequency 20 pps or more, preferably 20 to 2000 pps, more preferably 100 to 10 pps
00 pps, pulse width 0.1 μsec or more, preferably 0.1
A pulse-type high-frequency voltage of 10 to 10 μsec, more preferably 2 to 5 μsec is employed, the distance between the electrodes is 30 mm or less, preferably 10 to 30 mm, and the average electric field strength represented by the applied voltage (peak value) / the distance between the electrodes is 30 kV. / cm or more, preferably 40 to
It is desirable to make it 180 kV / cm and follow the conventional procedure.

By using the corona discharge generator according to the present invention, the surface of the material to be treated can be efficiently and uniformly subjected to corona discharge treatment.

The apparatus of the present invention comprises a plastic film,
The present invention may be applied to a flat surface such as a plastic sheet, a plastic panel, a natural fiber cloth, a synthetic fiber cloth, and a nonwoven cloth, but is also useful for a plastic molded article having a three-dimensional structure. Hereinafter, the present invention will be described with reference to examples.

[0030]

【Example】

Example 1 A corona discharge generator (FIG. 12) according to the present invention using a tetrafluoroethylene-perfluoroether copolymer film (hereinafter, PFA film) using a capsule-type discharge electrode and a roll-type counter electrode shown in FIG. 4 was used. And subjected to corona discharge treatment under the following conditions. The counter electrode (10) and the dielectric (11) were formed in a drum shape and used while being rotated by a film belt (12).

(Corona discharge conditions) The radius of the terminal hemisphere of the discharge electrode is 15.5 mm, 27.5 mm or 40.0 m, respectively.
When the distance between the electrodes was set to 70 mm to 10 mm, spark generation during corona discharge was observed. Other conditions are shown below. Discharge conditions: Discharge part of discharge electrode: Length; 300 mm, radius; same as radius of hemisphere Repetition frequency: 100 pps Pulse peak value: 100 kV Pulse width: 2 μsec Maximum average electric field intensity: 100 kV / cm Processing speed: 6 m / min Dielectric Thickness: 7mm L in FIG. 12: 100mm

As a comparative example, the discharge electrode was set to have a discharge part length 3
The results are shown in Table 1 below together with the results when a knife-type electrode having a thickness of 00 mm (without a terminal portion) was used.

[Table 1]

From this result, it has been clarified that the occurrence of spark can be prevented by taking the protrusion of the terminal portion.
Further, it has been clarified that the larger the pipe diameter, the more the occurrence of spark can be prevented. This is considered to be because the electric field can be diffused as the pipe diameter increases.

Embodiment 2 As shown in FIG.
Using a corona discharge generator of the present invention, which is a knife-shaped electrode having a diameter of 20 mm, a pipe-shaped portion having a radius of 20 mm, and a discharge portion having a length of 300 mm, a PFA film (40 μm thick) is corona-coated while blowing oxygen, argon or helium with a gas feeder. It was subjected to a discharge treatment. The spraying conditions and discharge conditions are shown below. The film to be processed was processed 5 times and 10 times while being conveyed at a processing speed of 6 m / min.

Blowing condition: Gas supply amount: 2 liter / min Slit: 10 mm long × 260 mm wide Discharge condition: Discharge electrode: Knife type electrode Distance between electrodes: 10 mm Discharge part length of discharge electrode: 300 mm (effective 260 mm) Repetition frequency: 100 pps Pulse height: 100 kV Pulse width: 2 μsec Maximum average electric field strength: 100 kV / cm Dielectric thickness: 5 mm

The wettability of the film subjected to the corona discharge treatment 5 times and 10 times while blowing the above gas was evaluated by measuring the water contact angle with a contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.). The water contact angle of the film not subjected to the corona discharge treatment was 116 °. Figure 1 shows these results.
It is shown in FIG.

It has been found that when corona discharge treatment is performed while the gas is sprayed on the plastic surface, the wettability of the plastic surface with water is more efficiently improved. At this time, no spark is generated.

[0038]

According to the corona discharge generator of the present invention, even if a high voltage is applied, the distance between the electrodes is reduced, or even if the dielectric material is made thin, sparks do not occur and the corona discharge can be performed efficiently and uniformly. Discharge processing can be easily performed. Further, when a specific gas flow is blown to the corona discharge region, the efficiency is further improved.

[Brief description of the drawings]

FIG. 1A is a vertical cross-sectional view of a discharge electrode having a wire shape and a spherical terminal portion passing through an axis of a discharge part, and FIG. 1B is a view when viewed from the discharge part axial direction. 1 shows a schematic perspective view.

2A is a vertical sectional view of a discharge electrode having a knife-shaped discharge portion and a spherical terminal portion passing through the axis of the discharge portion, and FIG. 2B is a view when viewed from the discharge portion axial direction. 1 shows a schematic perspective view.

FIG. 3A is a vertical cross-sectional view of a discharge electrode having a round bar shape and a discharge electrode formed of a spherical terminal portion passing through the axis of the discharge portion, and FIG. 1 shows a schematic perspective view of FIG.

FIG. 4 (a) is a vertical cross-sectional view of a capsule-type discharge electrode including a hemispherical terminal portion and a pipe-shaped discharge portion having a radius equal to the radius thereof, taken through the axis of the discharge portion;
(B) is a schematic perspective view when viewed from the discharge part axial direction.

FIG. 5 (a) is a vertical view passing through the axis of the discharge part for a discharge electrode composed of a plurality of discharge parts having a wire shape and a capsule-shaped terminal part comprising a hemispherical part and a pipe-shaped part having a radius equal to the radius thereof A cross-sectional view is shown, and (b) is a schematic perspective view when viewed from the axial direction of the discharge part.

FIG. 6A is a perspective view of a discharge electrode including a terminal portion having a donut-shaped ring shape and a discharge portion having a wire shape when viewed from the counter electrode side, and a vertical cross-sectional view passing through the axis of the discharge portion. (B) is a cross-sectional view taken along line (a) perpendicular to the axis of the discharge part in (a), and (c) corresponds to (b) in the case where there are three wires as the discharge part. FIG.

7A is a perspective view of a discharge electrode including a terminal portion having a donut-shaped ring shape and a net-shaped discharge portion when viewed from the counter electrode side, and FIG. FIG. 4 shows a cross-sectional view when cut perpendicular to a plane.

FIG. 8A is a schematic view of a discharge electrode including a terminal portion having a donut-shaped ring shape and a plate-shaped discharge portion when viewed from the counter electrode side, and FIG. FIG. 3 shows a cross-sectional view when cut perpendicular to a partial plane.

FIG. 9A is a perspective view of a discharge electrode including a terminal portion having a donut-shaped ring shape and a discharge portion having a wire shape when viewed from the counter electrode side;
(B) is a cross-sectional view taken along line (a) perpendicular to the axis of the discharge part in a straight line x, and (c) is a cross-sectional view corresponding to (b) in the case of having a gas flow outlet. Show.

10A is a perspective view of a discharge electrode including a terminal portion having a donut-shaped ring shape and a reticulated discharge portion when viewed from the counter electrode side, and FIG.
2 shows a cross-sectional view taken along a straight line x and perpendicular to the plane of the discharge portion, and FIG. 3C shows a cross-sectional view corresponding to FIG.

FIG. 11 (a) shows a side view of a capsule-type discharge electrode corresponding to a case where a gas flow is blown to a corona discharge region and a view when viewed from the counter electrode side,
(B) is a cross-sectional view taken along a line x in FIG. (A) perpendicular to the axis of the discharge part, and shows the flow of gas flow.

FIG. 12 is a schematic configuration diagram of a corona discharge generator used in Example 1.

FIG. 13 is a schematic configuration diagram of a corona discharge generator used in Example 2.

FIG. 14 is a diagram showing a water contact angle on the surface of a material to be treated after corona discharge treatment while blowing various gas flows.

FIG. 15A is a schematic view of a roll-shaped counter electrode and a curved discharge electrode viewed from the side, and FIG.
Shows a schematic vertical sectional view of a curved discharge electrode.

[Explanation of symbols]

1: spherical terminal part, 2: discharge part, 3: hemispherical terminal part, 4:
Donut-shaped ring-shaped terminal portion, 5: net-shaped discharge portion, 6: plate-shaped discharge portion, 7: gas flow outlet, 8: slit, 9: gas flow supply port, 10: counter electrode, 11: dielectric, 12: Film belt, 13: material to be treated, 14: drum shaft, 1
5: capsule-type terminal, 16: spherical part in terminal,
17: pipe-shaped part in the terminal part, 18: roll-shaped counter electrode, 19: curved discharge electrode, 20: curved terminal part, 21: curved discharge part.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Osamu Katayama 19-17 Ikedanakacho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (11)

[Claims] 1. A corona discharge generator comprising at least a discharge electrode and a counter electrode and applying a high voltage between both electrodes, wherein the discharge electrode comprises a discharge portion and a terminal portion, and the terminal portion has a projection. A corona discharge generator characterized by not performing. 2. The corona discharge generator according to claim 1, wherein the terminal portion has a spherical or hemispherical shape with a radius of 5 mm or more. 3. The corona discharge generator according to claim 1, wherein the discharge section has a wire, knife or rod shape. 4. The corona discharge generation according to claim 1, wherein the discharge portion has a pipe shape having a radius of 15 mm or more, and the terminal portion has a hemispherical shape having a radius equal to the radius of the discharge portion. apparatus. 5. The corona discharge generator according to claim 1, wherein the terminal portion has a capsule-like shape comprising a hemisphere having a radius of 15 mm or more and a pipe-shaped portion having a radius equal to the hemisphere. 6. The corona discharge generator according to claim 5, wherein the discharge section has a wire, knife or rod shape. 7. A slit is provided on the opposite electrode side of the discharge portion, and a supply port is provided on the opposite side. A gas selected from air, oxygen or a rare gas is supplied to the supply port, and the gas is supplied from the slit to a corona. 5. The corona discharge generator according to claim 4, wherein the corona discharge generator is sprayed on a discharge area. 8. The end portion is formed of a pipe having a radius of 5 mm or more, and has a donut-shaped ring shape.
The corona discharge generator according to claim 1. 9. The corona discharge generator according to claim 8, wherein the discharge section has a wire, a knife, a rod, or a planar shape. 10. A method in which air, oxygen or a rare gas is blown from the upper portion of the discharge electrode to the corona discharge region.
The corona discharge generator according to claim 1, 2, 3, 5, 6, 8, or 9. 11. A voltage applied between both electrodes has a peak value of 10
300kV, repetition frequency 20pps or more, pulse width 0.
2. A pulse-type high-frequency voltage of 1 .mu.sec or more, wherein a distance between the electrodes is 30 mm or less, and an average electric field strength represented by applied voltage (peak value) / distance between the electrodes is 30 kV / cm or more. The corona discharge generator according to any one of claims 10 to 10.