JP2006244794A - Discharge tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a discharge tube capable of preventing peel-off of a trigger discharge film due to shock of discharge generated at a discharge gap between discharge electrodes, and exerting an excellent discharge delay prevention effect. <P>SOLUTION: In the discharge tube 10, both-end openings of a case member 12 is sealed airtightly with a pair of lid members 14, 14 serving also as discharge electrodes to make up an airtight envelope 16, in which 16 discharge gas is sealed in, a discharge gap 22 is formed between discharge electrode parts 18, 18 of the lid members 14, 14, and a plurality of trigger discharge films 28 with both ends arranged so as to separate the lid members 14, 14 from micro discharge gaps 26 are formed on inner wall faces of the case member 12. The discharge electrode parts 18, 18 is enveloped by a ring-shape member 32 inserted into the case member 12, and at the same time, a plurality of trigger discharge films 28 with both ends arranged so as to separate the lid members 14, 14 from micro discharge gaps 26 are formed at an outer periphery face of the ring-shape member 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge tube, and in particular, as a switching spark gap for supplying a constant voltage for lighting or ignition to a high pressure discharge lamp such as a projector or a metal halide lamp of an automobile, or an ignition plug of a gas cooker, or The present invention relates to a discharge tube that can be suitably used as a gas arrester for absorbing surge voltage.

  As this type of discharge tube, the present applicant has previously proposed Japanese Patent Application Laid-Open No. 2003-7420. As shown in FIG. 6, the discharge tube 60 is hermetically sealed with a pair of lid members 64, 64 that also serve as discharge electrodes, at both ends of a cylindrical case member 62 made of an insulating material that opens at both ends. Thus, an airtight envelope 66 is formed, and a predetermined discharge gas is sealed in the airtight envelope 66.

The lid member 64 includes a flat discharge electrode portion 68 that protrudes greatly toward the center of the hermetic envelope 66, and a joint portion 70 that contacts the end surface of the case member 62. A predetermined discharge gap 72 is formed between the discharge electrode portions 68 and 68.
A plurality of pairs of trigger discharge films 78 and 78 are formed in the circumferential direction of the inner wall surface 74 of the case member 62 so as to face each other with a minute discharge gap 76 therebetween. Of the pair of trigger discharge films 78, 78, one trigger discharge film 78 is electrically connected to one discharge electrode portion 68, and the other trigger discharge film 78 is electrically connected to the other discharge electrode portion 68. It is connected.

On the surface of the discharge electrode portion 68, an insulating film 80 containing an alkali iodide effective for stabilizing the discharge start voltage is formed. As this alkali iodide, the simple substance or mixture of alkali iodides, such as potassium iodide (KI), sodium iodide (NaI), cesium iodide (CsI), and rubidium iodide (RbI), corresponds.
As the discharge gas sealed in the hermetic envelope 66, for example, a rare gas such as argon, neon, helium, xenon, or an inert gas such as nitrogen gas or a mixed gas is applicable. Also, a single or mixed gas of a rare gas or an inert gas, a mixed gas of negative polarity gas such as H ₂ corresponds.

When a voltage equal to or higher than the discharge start voltage of the discharge tube 60 is applied between the discharge electrode portions 68, 68 of the discharge tube 60 having the above-described configuration, an electric field is generated in the minute discharge gap 76 between the trigger discharge films 78, 78. As a result, electrons are emitted into the minute discharge gap 76, and creeping corona discharge as a trigger discharge is generated. Next, this creeping corona discharge shifts to glow discharge due to an electron priming effect. Then, this glow discharge is transferred to the discharge gap 72 between the discharge electrode portions 68 and 68, and is transferred to arc discharge as the main discharge.
JP 2003-7420 A

  The trigger discharge film 78 is formed to supply a function of preventing initial delay by supplying initial electrons, and a discharge generated in the discharge gap 72 between the discharge electrode portions 68 and 68 ( As a result, the function of preventing discharge delay gradually deteriorated.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to prevent the trigger discharge film from being peeled off due to the impact of discharge generated in the discharge gap between the discharge electrode portions, and to prevent excellent discharge delay. The object is to realize a discharge tube having an effect.

  In order to achieve the above object, a discharge type surge absorbing element according to the present invention hermetically seals both end openings of a case member made of an insulating material having both ends opened with a pair of lid members also serving as discharge electrodes. Thereby forming a hermetic envelope, enclosing a discharge gas in the hermetic envelope, and forming a discharge gap between the discharge electrode portions of the lid member disposed in the hermetic envelope. A discharge tube in which a trigger discharge film is formed on the inner wall surface of the case member so that both ends of the case member are separated from the lid member by a minute discharge gap, and the discharge electrode portion is inserted into the case member In addition to being surrounded by a ring-shaped member, a trigger discharge film is formed on the outer peripheral surface of the ring-shaped member so that both ends thereof are spaced apart from the lid member by a minute discharge gap.

In the discharge tube according to the present invention, since the discharge electrode portion is surrounded by the ring-shaped member inserted in the case member, the impact of the discharge (arc discharge) generated in the discharge gap between the discharge electrode portions is the above ring. The trigger discharge film can be prevented from being peeled off by being absorbed by the shaped member.
Further, in the discharge tube of the present invention, since the trigger discharge film is formed not only on the inner wall surface of the case member but also on the outer peripheral surface of the ring-shaped member, a large amount of initial electrons can be supplied, which is excellent. There is an effect of preventing discharge delay.

Hereinafter, a discharge tube 10 according to the present invention will be described with reference to FIGS. 1 is a schematic cross-sectional view showing a discharge tube 10 according to the present invention, FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a view of the discharge tube 10 with a ring-shaped member 32 to be described later removed. 4 is a front view showing the ring-shaped member 32, and FIG. 5 is a schematic cross-sectional view taken along the line BB of FIG.
As shown in FIGS. 1 and 2, a discharge tube 10 according to the present invention has a pair of lids that serve as discharge electrodes at both ends of a cylindrical case member 12 made of ceramic as an insulating material having both ends open. The hermetic envelope 16 is formed by hermetically sealing with the members 14 and 14.

The lid member 14 includes a planar discharge electrode portion 18 projecting greatly toward the center of the hermetic envelope 16, and a joint portion 20 in contact with the end surface of the case member 12. A predetermined discharge gap 22 is formed between the discharge electrode portions 18 and 18.
The lid member 14 provided with the discharge electrode portion 18 and the joint portion 20 is made of oxygen-free copper or zirconium copper containing oxygen-free copper containing zirconium (Zr). Note that the end face of the case member 12 and the joint portion 20 of the lid member 14 are hermetically sealed through a sealing material (not shown) such as silver solder.

As shown in FIGS. 2 and 3, the inner wall surface 24 of the case member 12 is arranged such that both ends of the case member 12 are disposed with a small discharge gap 26 between the lid members 14 and 14 that also serve as discharge electrodes. A plurality of trigger discharge films 28 are formed. 2 and 3 exemplify the case where eight trigger discharge films 28 are formed at intervals of 45 degrees in the circumferential direction of the inner wall surface 24 of the case member 12.
The trigger discharge film 28 is made of a conductive material such as a carbon-based material. The trigger discharge film 28 can be formed, for example, by rubbing a core material made of a carbon-based material.

A film 30 containing a mixture of cesium bromide (CsBr) and titanium (Ti) that has an effect of preventing an increase in initial discharge start voltage is formed on the surface of the discharge electrode portion 18.
The initial discharge start voltage refers to the first discharge start voltage when the discharge tube is repeatedly operated, and the second and subsequent discharge start voltages subsequent to the initial discharge start voltage are referred to as follow-up discharge start voltages.
The coating 30 can be formed by applying a mixture of a cesium bromide powder and a titanium powder to a binder composed of a sodium silicate solution and pure water on the surface of the discharge electrode portion 18. Alternatively, the binder to which cesium bromide is added and titanium powder added and mixed can be applied to the surface of the discharge electrode portion 18 to form.
The particle size of the titanium powder is, for example, 10 to 45 μm.
In this case, the mixing ratio of cesium bromide and titanium is preferably 20 to 80% by weight for cesium bromide and 80 to 20% by weight for titanium in order to effectively prevent an increase in initial discharge start voltage. .
The mixture ratio of the cesium bromide and titanium and the binder is such that the mixture of cesium bromide and titanium is 0.01 to 25% by weight and the binder is 99.99 to 75% by weight.
The mixing ratio of the sodium silicate solution and pure water in the binder is such that the sodium silicate solution is 0.01 to 70% by weight and the pure water is 99.99 to 30% by weight.

The pair of discharge electrode portions 18 and 18 are surrounded by a ring-shaped member 32 inserted into the case member 12. As a result, the discharge electrode portions 18 and 18 are disposed in the space 36 surrounded by the ring-shaped member 32, while the trigger discharge film 28 formed on the inner wall surface 24 of the case member 12 is outside the ring-shaped member 32. It will be arranged in the space 38. Further, as shown in FIGS. 1 and 2, a linear trigger discharge film disposed on the outer peripheral surface of the ring-shaped member 32 with a small discharge gap 26 and the lid members 14, 14 also serving as discharge electrodes. Four 28 are formed at intervals of 90 degrees in the circumferential direction.
The ring-shaped member 32 is made of an insulating material such as alumina, and a cut portion 34 is formed as shown in FIGS. 4 and 5. The notch 34 communicates with the space 36 where the discharge electrode 18 surrounded by the ring-shaped member 32 is present and the space 38 outside the ring-shaped member 32 where the trigger discharge film 28 is present. It is provided.

A predetermined discharge gas is sealed in the hermetic envelope 16. As this discharge gas, for example, a rare gas such as argon, neon, helium, or xenon, or an inert gas such as nitrogen gas or a mixed gas is applicable. Also, a single or mixed gas of a rare gas or an inert gas, a mixed gas of negative polarity gas such as H ₂ corresponds.

  In the discharge tube 10 of the present invention, when a voltage equal to or higher than the discharge start voltage of the discharge tube 10 is applied between the pair of lid members 14 and 14 also serving as discharge electrodes, the inside of the case member 12 The electric field concentrates in the minute discharge gap 26 between the both ends of the trigger discharge film 28 formed on the outer peripheral surface of the wall surface 24 and the ring-shaped member 32 and the lid members 14 and 14, whereby electrons are emitted into the minute discharge gap 26. Creeping corona discharge as trigger discharge occurs. Next, this creeping corona discharge shifts to glow discharge due to an electron priming effect. Then, the glow discharge is transferred to the discharge gap 22 between the discharge electrode portions 18 and 18, and the arc discharge is performed as the main discharge.

  As described above, the ring-shaped member 32 includes a space 36 where the discharge electrode portion 18 surrounded by the ring-shaped member 32 exists, and a space 38 outside the ring-shaped member 32 where the trigger discharge film 28 exists. Since the communicating cut 34 is formed, the flow of electrons discharged into the minute discharge gap 26 and the transition from the creeping corona discharge to the arc discharge in the discharge gap 22 are not hindered.

In the discharge tube 10 of the present invention, since the pair of discharge electrode portions 18 and 18 are surrounded by the ring-shaped member 32 inserted into the case member 12, the discharge generated in the discharge gap 22 between the discharge electrode portions 18 and 18 ( The arc discharge) is absorbed by the ring-shaped member 32, and the trigger discharge film 28 can be prevented from peeling off.
Further, in the discharge tube 10 of the present invention, the trigger discharge film 28 is formed not only on the inner wall surface 24 of the case member 12 but also on the outer peripheral surface of the ring-shaped member 32, so that a large amount of initial electrons are supplied. And has an excellent effect of preventing discharge delay.

Furthermore, since the discharge tube 10 of the present invention formed on the surface of the discharge electrode portion 18 a coating 30 containing a mixture of cesium bromide and titanium that has an effect of preventing an increase in the initial discharge start voltage, It is possible to prevent the discharge start voltage from increasing and to realize a long-life discharge tube 10 that does not cause an initial discharge delay.
Titanium contained in the coating 30 of the discharge tube 10 of the present invention has a very large ionization tendency, so that the titanium ionizes discharge gas molecules. Can be supplied in large quantities.

It is a schematic sectional drawing which shows the discharge tube which concerns on this invention. It is an AA schematic sectional drawing of FIG. It is a schematic sectional drawing which shows the discharge tube of the state which removed the ring-shaped member. It is a front view which shows a ring-shaped member. It is BB schematic sectional drawing of FIG. It is sectional drawing which shows the conventional discharge tube.

Explanation of symbols

10 discharge tube
12 Case material
14 Lid member
16 Airtight envelope
18 Discharge electrode
22 Discharge gap
26 Micro discharge gap
28 Trigger discharge membrane
30 coating
32 Ring-shaped member
34 notch
36 space
38 space

Claims (1)

An airtight envelope is formed by hermetically sealing the opening at both ends of the case member made of an insulating material with both ends open with a pair of lid members that also serve as discharge electrodes, and a discharge is generated in the airtight envelope. Gas is sealed, and a discharge gap is formed between the discharge electrode portions of the lid member disposed in the hermetic envelope, and both ends of the case member are disposed on the inner wall surface of the case member. A discharge tube formed by forming a trigger discharge film spaced apart from each other, wherein the discharge electrode portion is surrounded by a ring-shaped member inserted into the case member, and both ends of the ring-shaped member are disposed on the outer peripheral surface of the ring-shaped member. A discharge tube characterized in that a trigger discharge film is formed which is disposed with a gap between the lid member and the minute discharge gap.

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