JPH01266865A - Acicular electrode for corona discharge and ion generator using said electrode - Google Patents

Abstract

PURPOSE:To prevent generation of dust by closely sticking a hollow cone (dielectric substance) made of ceramic to the tip of a conductor impressed with high voltage and forming it into an acicular electrode for corona discharge. CONSTITUTION:The tip 1a of a metallic rod 1 is worked to an acicular shape and a hollow cone 2 made of ceramic is formed into a hollow conical shape by working a transparent quartz pipe and the inner surface is finished so that it is thoroughly brought into contact with the tip 1a of the metallic rod 1. The wall thickness of the tip part 2a of this cone 2 is made as thin as possible in comparison with the other part and finished at least to 2mm or below desirably to about 0.1mm. Thereafter both the metallic rod 1 and the cone 2 are fixed by an adhesive 3 and the outside of the metallic rod 1 is covered with an insulating tube 4 and the adhesive joint to the quartz cone is covered with a silicon adhesive sealer 5 so that the metallic part is not exposed. The other end 1b of the metallic rod is connected with a high voltage generator and when it is impressed with AC high voltage, corona discharge is caused from the tip of the quartz cone and ions are generated. In this case, dust is not generated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention applies to the application of high voltage in air.
The present invention relates to a needle-shaped electrode that generates ions by corona 111 electricity from this electrode, and an ion generator using the electrode.

[Conventional technology] Precision electronic components and high purity materials are manufactured in a low humidity environment (40 to 45% R1+) while being transported using containers such as high-resistance, easily-charged plastics, Heleys, and pallets. When processing and inspecting, static electricity causes problems such as short circuits and reduced yields.This is because precision electronic components charged with static electricity may cause dielectric breakdown.
This means that the electrostatic charge attracts dust with an opposite charge due to the charged potential, shorting out minute circuits or contaminating high-purity materials. In recent years, as the density of precision electronic components and the purity of their materials have increased, the production environment has become required to be ultra-highly clean, and the electrostatic resistance of precision electronic components has also decreased, making them increasingly susceptible to static electricity. Production problems are a problem.

[Problem to be solved by the invention] Static electricity countermeasures can be roughly divided into two methods: one is to ground the object to quickly leak the electric charge, and the other is to neutralize the electric charge with ions. If the resistance is high, it is difficult to ground and leak the charge quickly.

In such a case, by applying a high DC or AC voltage to the needle-shaped gold FA electrode, a Ko discharge is generated at the tip of the needle, which ionizes the air around the electrode into positive and f1 ions.
A method is used in which the charge is carried by a uniform air flow in the room and the charge on the charged body is neutralized with ions of the opposite polarity.

However, in such an ion generator, when ions are generated from the metal electrode by corona discharge, metal particles are ejected into the air. The amount of g emitted from the electrode varies depending on the structure of the ion generator and the operating system f↑, but
For example, the commonly used tungsten electrode is 40cm/
When the electrode is placed in an airflow of S and 15 kV of alternating current is applied, approximately 2.6 x 10' particles of dust with a diameter of 003 μm or more are mixed into the air of 1[[3] near the electrode.

Naturally, if these metal fine particles adhere to or mix with M-density electronic components or high-purity materials, they will render them defective.

[Means for Solving the Problems] The present invention improves the deficiency λ of the conventional ion generator described above, and uses a needle-shaped electrode that generates clean f ions without generating metal particles, and the electrode. The present invention provides an ion generator with a high quality.

The basic principle of the present invention is to cover the metal needle electrode used in conventional ion generators with a dielectric material such as ceramics, apply a high AC voltage to the metal electrode, and generate a corona discharge through the dielectric material. It ionizes the air around the electrode and generates ions.

In other words, the present invention creates a corona t by attaching a ceramic hollow cone (dielectric material) to the tip of a conductor to which a high voltage is applied.
This is a needle-like electrode for III, and is used in an ion generator using this electrode. The ceramic hollow cone has a ceramic thickness of 2 at the tip.
mm or less, preferably on the order of 0.1 mm. The tip of a conductor (metal type ViA) is fitted into the hollow portion of this hollow cone, or is closely attached using a conductive adhesive.

Furthermore, glass having approximately the same coefficient of thermal expansion as the 'fJ lightning body is heat-welded to the tip of the needle-shaped conductor.

[Example] The detailed configuration of the present invention will be explained using the drawings.

FIG. 1 shows the configuration of one embodiment of the present invention. In the figure, 1 is a metal rod (conductor) with a diameter of φ2,
Its tip i a +, t ! It is processed into a + shape. The metal electrodes of conventional ion generators have a shape approximately like this. Reference numeral 2 denotes a hollow cone made of ceramics, which is formed by processing a transparent quartz tube into a hollow cone shape, and its inner surface is finished so as to make perfect contact with the tip 1a of the metal rod 1. The wall thickness of the tip 2a of the ceramic hollow cone 2 is made as thin as possible than the other parts, and is finished to at least 2s or less, preferably on the order of 0.1. It is particularly necessary that the tip 1a of the metal rod contacts the inside of the tip 2a of the hollow cone.

Thereafter, the metal rod 1 and the hollow cone 2, which is a quartz cone, are fixed with an adhesive 3. In the example, an epoxy resin adhesive was used. The outside of the metal rod 1 was covered with an insulating tube 4 such as an insulating vinyl tube, and the adhesive part with the quartz cone was covered with a silicon adhesive sealing material 5 to prevent the metal part from being exposed.

When the other end 1b of the metal rod is connected to a high voltage generator (not shown) and a high alternating current voltage is applied, a corona discharge occurs from the tip of the quartz forceps and ions are generated.

FIG. 2 shows the configuration of the measuring device used to measure the amount of ions generated in this example.

In FIG. 2, an AC high voltage generated by a power supply section 8 is applied to the quartz electrode section 7 of the ion generator 6, and the blower 10
Wind is blown onto the ion generator so that the wind speed passing through the electrode part 7 is approximately 1 TIL/S, and the ion counter 9 is placed downwind of the electrode part 7 from the electrode part 7 to 1TrLI!
! I installed it.

To measure the amount of dust generated from the electrodes, a neutralizer that electrostatically neutralizes the charge on dust particles and a condensation nucleus type particle counter were connected in series. The measurement results of particles with a particle size of 0.03 μm or more are shown in Table 1 in comparison with a conventional ion generator. The amount of dust generated was measured in a class 1 clean room.

Table 1 As is clear from Table 1, the ion generator of the present invention can generate approximately the same amount of ion suspension as the conventional ion generator, and furthermore, there is no dust generation.

Next, another embodiment will be explained with reference to the drawings.

FIG. 3 shows the configuration of another embodiment of the present invention.

The shape of the hollow quartz forceps (hollow cone) 2 is the same as in the first embodiment described above. After applying conductive adhesive 11 to the inside of quartz cone 2, metal rod 1 is inserted and fixed. in this case,
The tip of the metal rod does not need to be shaped into a needle. As the conductive adhesive 11, for example, one having a silver thread filler and an epoxy resin as a binder may be used, or a water-based colloidal graphite concentrate may be used. The other parts of the electrode are constructed in the same manner as in Example 1. The ion generator using the electrode configured in this manner can generate the same amount of ions as in Example 1, and generates no amount of dust. In the above embodiments, quartz was used as the ceramic, but glass, alumina porcelain, or alumina-silica porcelain may have the same effect.

Further, although a hollow quartz cone is used in the above embodiment, a hollow pyramid may also be used, and a general method of coating a metal cone with ceramics can also be used. That is, it is possible to use an electrode coated with glass by processing a metal rod into a needle shape and then heating and welding glass having a coefficient of linear expansion that is approximately the same as that of the metal rod to the metal portion.

Furthermore, it is also possible to use an electrode coated with glass by oxidizing a metal rod processed into a needle shape to form an oxide film on the surface and then welding glass.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, a sword-shaped electrode with excellent corona discharge can be obtained, and an ion generator without dust generation can be provided using this electrode. can do.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of one embodiment of the present invention, FIG. 2 is an explanatory diagram showing the configuration of an embodiment in which the effects of the present invention were measured,
FIG. 3 is an explanatory diagram that does not show the structure of another embodiment of the present invention. 1... Conductor (metal rod), 1a... Tip, 1b...
・Other end. 2... Hollow cone (quartz cone) made of Viramix. 2a... Tip portion, 3... Adhesive, 4... Insulating duplex. 5... Adhesive sealing material, 11... Conductive adhesive. Applicant: Takasago Thermal Engineering Co., Ltd. Japan Ozone Co., Ltd.

Claims (1)

[Scope of Claims] 1. A conductor to which a high voltage is applied in an ion generator that applies a high DC or AC voltage to a needle-shaped electrode placed in the air and ionizes the gas around the electrode by corona discharge. A needle-shaped electrode for corona discharge characterized by having a ceramic hollow cone closely attached to the tip of the electrode. 2. The needle-shaped electrode for corona discharge according to claim 1, characterized in that the tip of the conductor is fitted into the hollow portion of the ceramic hollow cone. 3. Claim 1, characterized in that a conductor is bonded to the hollow portion of the ceramic hollow cone using a conductive adhesive.
Or the acicular electrode for corona discharge according to 2. 4. The needle-shaped electrode for corona discharge according to claim 1, 2 or 3, wherein the thickness of the ceramic at the tip of the ceramic hollow cone is 2 mm or less, preferably about 0.1 mm. 5. The corona discharge electrode according to claim 1, 2 or 3, wherein the hollow cone is made of transparent quartz. 6 In an ion generator that applies a high DC or AC voltage to a needle-shaped electrode placed in the air and ionizes the gas around the electrode by corona discharge, the heat generated is approximately the same as the coefficient of thermal expansion of the needle-shaped metal electrode. A needle-shaped electrode for corona discharge, characterized in that a glass having a coefficient of expansion is heat-welded to the needle-shaped part of the metal electrode. 7. An ion generator, characterized in that the needle-like electrode for corona discharge according to any one of claims 1 to 6 is arranged to face an upper part of a charged object, and a corona is generated at the tip of a ceramic hollow cone.