JPH0817548A - Discharge type guide absorbing device and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance response characteristics to surge by arranging a defective part formed by removing part of a dielectric layer between lead wires of a discharge type surge absorbing device. CONSTITUTION:In a discharge type surge absorbing device 10, a pair of discharge electrodes 14, 14 connected with lead wires 12, 12 to one end of them are placed in parallel at specified intervals, and a discharge space 16 is formed between the electrodes 14, 14. Discharge gas such as noble gas is sealed in a gastight container 18, and a dielectric layer 20 with high surface discharge characteristics such as nickel oxide is formed inside the container 18. A large number of auxiliary electrodes 22 comprising particles or blocks of metal with high discharge characteristics are scatteringly arranged at least between the lead wires on the surface of the dielectric layer 20. By irradiating YAG laser and evaporating the irradiated part, a defective part 26 is formed in a part of the dielectric layer 20. By the defective part 26, drop in insulating resistance of the dielectric layer caused when surge is applied is prevented, and arc discharge is preferably generated in a discharge gap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge type surge absorbing element which absorbs a surge by utilizing a discharge phenomenon in a discharge gap enclosed in an airtight container and a method for manufacturing the same, and more particularly to an air discharge in the discharge gap. The present invention relates to a discharge type surge absorbing element having improved surge response performance by using a creeping corona discharge on the surface of a dielectric layer and an air discharge in an auxiliary discharge gap as a trigger means, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in order to protect an electronic circuit element from a surge such as a transient abnormal voltage intruding into an electronic device or an induced lightning, a discharge type surge absorption utilizing a discharge phenomenon in a discharge gap enclosed in an airtight container. The element is used. Since such a discharge type surge absorbing element absorbs a surge by using arc discharge which is a main discharge, it has an advantage that it has a large current withstanding capability, but has a drawback that it has poor surge response performance. Therefore, a technique for improving surge response performance by connecting a dielectric having good creeping discharge characteristics in parallel to the discharge gap and using the creeping corona discharge on the surface of the dielectric as a trigger for the main discharge in the discharge gap. Exists (Japanese Patent Publication No. 5-7835, Japanese Patent Publication No. 5-87)
No. 36).

As shown in FIG. 4, this discharge type surge absorbing element 50 has barium oxide, lanthanum hexaboride and the like on the surface of an electrode base 52a made of a metal material having good discharge characteristics such as nickel, copper and iron. Emitter layer 52b composed of the emitter material of
The rod-shaped discharge electrodes 52 and 52 formed by adhering are arranged in parallel with each other with a predetermined discharge gap 54 therebetween, and this is put together with a predetermined discharge gas in an airtight container 56 formed by processing a glass tube. The lead wires 58, 58 that are enclosed and connected to the lower ends of both discharge electrodes 52, 52 are led out to the outside of the airtight container 56, and at the same time at least between the lead wires 58, 58 on the inner surface of the airtight container 56, the creeping discharge characteristic It is formed by depositing a good dielectric layer 60. The discharge gap 54 and the dielectric layer 60 form the lead wires 58, 58.
Are connected in parallel via.

As shown in FIG. 5, which is an enlarged view of the connecting portion between the lead wires 58, 58 and the airtight container 56, from the surface of the dielectric layer 60, a granular or conductive material such as nickel, copper, iron or the like is formed. A large number of lump-shaped auxiliary discharge electrodes 62 are projected, and an auxiliary discharge gap much smaller than the above-mentioned discharge gap 54 is provided between the lead wire 58 and the auxiliary discharge electrodes 62 and between each auxiliary discharge electrode 62.
64 are formed.

However, when a surge is applied to the discharge type surge absorbing element 50 through the lead wires 58, 58, a creeping corona discharge is immediately generated on the surface of the dielectric layer 60 between the lead wires 58, 58. Then the surge absorption is started. Then, due to the priming effect of electrons and ions emitted along with this creeping corona discharge, an air discharge is first generated in the narrow auxiliary discharge gap 64. Next, the air discharge in the auxiliary discharge gap 64 is transferred to the discharge gap 54 between the discharge electrodes 52, 52, and finally the surge is absorbed through the large current of the arc discharge.

As described above, this discharge type surge absorbing element 50
Uses the creeping corona discharge, which is excellent in surge response, as the trigger discharge to improve the surge response performance, and at the same time, the air in the auxiliary discharge gap 64 between the creeping corona discharge and the main discharge in the discharge gap 54. The generation of the main discharge is made smoother by interposing the discharge.

[0007]

By the way, the dielectric layer 60 and the auxiliary discharge electrode 62 are the electrode base 52a of the discharge electrode 52.
The emitter layer 52b or the metal forming the lead wire 58 is used as a material. For example, the nickel electrode base 52
a is inserted into the airtight container 56, and the electrode base 52a is subjected to high-frequency heating in a depressurized atmosphere associated with the evacuation process in the airtight container 56 to melt and scatter nickel on the surface of the electrode base 52a to form an inner surface of the airtight container 56. To adhere to. At the beginning of the exhaust process, air remains in the airtight container 56, and the molten and scattered nickel is oxidized on the way.Therefore, on the inner surface of the airtight container 56, first, a dielectric layer made of an insulating nickel oxide is formed.
60 is formed. Next, when air disappears in the airtight container 56 as the exhaust process progresses, the molten and scattered nickel adheres to the surface of the dielectric layer 60 without being oxidized, and a granular or lumped auxiliary discharge having conductivity is formed. The electrode 62 will be formed. In this way, if the dielectric layer 60 and the auxiliary discharge electrode 62 are formed by using the metal forming the electrode base 52a as a material, it is not necessary to separately prepare a special device or material, and the manufacturing process can be simplified. There is an advantage that you can.

However, it is difficult to precisely control the melting / scattering process of the metal forming the electrode substrate 52a, so that some of the metal particles 66 that should originally be scattered only on the surface of the dielectric layer 60 are It is buried and mixed in the dielectric layer 60 inevitably, and as a result, the insulation resistance of the dielectric layer 60 itself is lowered. Then, when the insulation resistance of the dielectric layer 60 is lowered in this way, when a surge is applied, the creeping corona discharge between the lead wires 58, 58 becomes a continuous state, and it becomes impossible to shift to the main discharge in the discharge gap 54. . Also, due to the continuation of this creeping corona discharge, the dielectric layer 60 may be peeled off in some cases, or partially melted and scattered due to heat generation, and trigger discharge does not occur even when the next surge is applied. In the discharge gap 54, the discharge cannot be transferred to the main discharge due to the discharge delay, and there is a risk that the large current cannot be absorbed by using the arc discharge. Of course, if only a very small amount of metal particles 66 are mixed in, there is no problem, but in order to realize air discharge in the auxiliary discharge gap 64, the auxiliary discharge electrode 62 should be formed on the dielectric layer 60 with a certain density or more.
Must be distributed on the surface of the dielectric layer 60, and as a result, a non-negligible amount of metal particles 66 will be buried / mixed inside the dielectric layer 60.

The present invention has been made in view of the above-mentioned conventional problems, and even when the auxiliary discharge electrode is formed by using the metal constituting the member housed in the airtight container, the inter-lead wires are formed. The purpose of the present invention is to realize a discharge type surge absorbing element that can effectively prevent a creeping corona discharge in a continuous state from occurring, and therefore can reliably generate an arc discharge in the discharge gap. It is an object of the present invention to obtain a manufacturing method capable of easily manufacturing an absorbing element.

[0010]

In order to achieve the above object, a discharge type surge absorbing element according to the present invention has a plurality of discharge electrodes connected with lead wires facing each other in an airtight container filled with discharge gas. A discharge gap is formed between the respective discharge electrodes, the lead wires of the respective discharge electrodes are led out to the outside of the airtight container, and a dielectric having good creeping discharge characteristics at least between the lead wires on the inner surface of the airtight container. A plurality of auxiliary discharge electrodes formed by using a metal forming a member housed in the hermetic container as a material on at least the surface of the dielectric layer to form a discharge layer. In a discharge type surge absorbing element formed by forming an auxiliary discharge gap smaller than the gap between the lead wires, a defect formed by removing a part of the dielectric layer at least between the lead wires on the inner surface of the hermetic container. Intervening part Characterized in that was.

The defective portion is formed, for example, in a band shape having a width of 50 to 300 μm that crosses between the lead wires. Further, a recess may be formed in a portion of the inner surface of the airtight container corresponding to the defective portion. The defective portion is formed, for example, by irradiating a laser beam from the outside of the glass airtight container to evaporate a part of the dielectric layer formed on the inner surface of the airtight container.

[0012]

When a surge is applied to the discharge type surge absorbing element constructed as described above, creeping corona discharge is immediately generated on the surface of the dielectric layer between the lead wires to start surge absorption. This creeping corona discharge acts as a trigger discharge, and due to the priming effect of electrons and ions emitted by this discharge, the distance from the surface of the dielectric layer is shorter than the discharge gap between the discharge electrodes and the gap length is narrower. In the discharge gap, an air discharge is promptly generated. Next, the air discharge in the auxiliary discharge gap is transferred to the discharge gap between the discharge electrodes within an extremely short time due to the priming effect of a large amount of electrons and ions emitted by the discharge. As a result, an arc discharge is generated in the discharge gap through the glow discharge, and the surge is absorbed through the large current of the arc discharge.

Between the lead wires, since a defective portion formed by removing a part of the dielectric layer is interposed, metal particles are mixed in the dielectric layer during formation of the auxiliary discharge electrode, which causes a dielectric loss. Even if the insulation resistance of the body layer itself is reduced, the insulation between the lead wires is maintained. Therefore, when the surge is applied, the creeping corona discharge is maintained between the lead wires, and the problem that the arc discharge cannot be generated in the discharge gap does not occur.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a vertical sectional view showing a discharge type surge absorber 10 according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA. In this discharge type surge absorbing element 10, a pair of discharge electrodes 14, 14 having lead wires 12, 12 connected at one end are arranged in parallel at a predetermined distance, and a discharge gap 16 is provided between both electrodes.
Is formed, and is enclosed in an airtight container 18 formed by processing a glass tube, and the lead wire 12 of each discharge electrode 14 is led out of the airtight container 18.

The discharge electrode 14 is made of a metal material having good discharge characteristics, such as nickel, copper or iron, which is processed into a rod or plate shape on the surface of an electrode substrate 14a, and is made of an emitter material such as barium oxide or lanthanum hexaboride. It is formed by depositing an emitter layer 14b. The lead wire 12 is made of Dumet wire (copper-coated iron-nickel alloy wire), 42-6 alloy wire, or the like.

A discharge gas composed of a rare gas, a nitrogen gas, a sulfur hexafluoride gas, or the like is enclosed in the airtight container 18, and the inner surface of the airtight container 18 has good creeping discharge characteristics such as nickel oxide. The dielectric layer 20 is formed. At least the lead wires 12, 12 on the surface of the dielectric layer 20
In the meantime, as shown in FIG. 3, a large number of auxiliary discharge electrodes 22 made of particles or lumps of metal having good discharge characteristics such as copper, nickel or iron are arranged in a scattered manner. A large number of auxiliary discharge gaps 24, which are much smaller than the discharge gaps 16 between the discharge electrodes 14 and 14, are formed between the lead wires 12 and the auxiliary discharge electrodes 22, and between the auxiliary discharge electrodes 22. .

Further, on the inner surface of the airtight container 18, there is a defective portion 26 formed by partially removing the dielectric layer 20. The defect portion 26 is formed in a strip shape having a width of about 50 to 300 μm, and as shown in FIG.
The dielectric layer 20 arranged between 2 and 12 is divided by the missing portion 26. A fine recess 28 having a depth of 20 μm or less is formed in a portion of the inner surface of the airtight container 18 corresponding to the defective portion 26.

Next, an example of a method of manufacturing the discharge type surge absorber 10 will be described. First, the lead wires 12, 12
An emitter material made of barium carbonate is adhered to the surfaces of the electrode bases 14a, 14a made of nickel connected to each other so as to expose a part of the surfaces of the electrode bases 14a, 14a. Then, the lead wires 12, 12 are aligned in the same direction and held by an aligning jig, the electrode base bodies 14a, 14a are opposed to each other at a predetermined interval, and this is inserted into a glass tube having both ends open,
The lead wires 12, 12 are housed so that the lower end portions of the lead wires 12 and 12 project outside from one end opening of the glass tube. Further, one end of the glass tube is heated by a gas flame to be melted, and the melted portion is crushed inward by a pincher to seal the lead wire 12,
The middle part of 12 is fixed to the sealing part of the glass tube, and the lower ends of the lead wires 12 and 12 are led out of the glass tube. At this time, by heating the glass tube in the air,
The exposed portions of the surfaces of the electrode bases 14a, 14a are oxidized to form nickel oxide.

Next, an exhaust device is connected to the other end of the glass tube, which is placed in a high-frequency coil for high-frequency heating, and when the glass tube is evacuated, barium carbonate as an emitter material is thermally decomposed. The discharge layers 14 are completed by forming emitter layers 14b, 14b made of barium oxide on the surfaces of the electrode bases 14a, 14a. At the same time, the exposed parts of the surfaces of the electrode bases 14a, 14a are melted and start to scatter due to the pressure reduction in the glass tube accompanying the exhaust. At the beginning of the evacuation process, since the residual air concentration in the glass tube is high, the electrode bases 14a, 14
Nickel composing a is oxidized during scattering to become nickel oxide, which is layered on the inner surface of the glass tube together with the nickel oxide formed on the surfaces of the electrode substrates 14a, 14a in the previous step, and the creeping discharge characteristic is excellent. A dielectric layer 20 of nickel oxide is formed.

After that, as the exhaust work progresses, the concentration of residual air in the glass tube decreases, and finally the scattered nickel is not oxidized. Therefore, if this operation is finished at the time when the non-oxidized nickel adheres to the surface of the dielectric layer 20 in a scattered manner, the granular or massive auxiliary discharge electrode 22 is formed. The auxiliary discharge electrode 22 is a lead wire.
It can also be formed by melting and scattering the metal (copper or barium) that constitutes 12 or the emitter layer 14b and adhering them to the surface of the dielectric layer 20 in a scattered manner.

Next, the exhausting operation removes residual air, carbon dioxide by the decomposition of barium carbonate, and impure gas emitted from the glass tube itself or a member housed in the glass tube to bring the inside of the glass tube into a high vacuum state. After that, fill the discharge gas, and further heat the other end of the glass tube,
This is melted and sealed off to form the airtight container 18.

Finally, from the outside of the airtight container 18, YAG is applied.
When a laser is applied, the laser beam passes through the glass and reaches the dielectric layer 20 on the inner surface of the airtight container 18 to evaporate it. By moving the irradiation position of this laser beam along a predetermined pattern, the band-shaped defective portion 26 is formed. Although the laser beam itself passes through the glass,
Due to the influence of the dielectric layer 20 that absorbs the laser beam and generates heat and melts, the inner surface of the airtight container 18 is melted and recessed, resulting
A recess 28 having a pattern corresponding to the defective portion 26 is formed at substantially the same time on a portion of the inner surface 18 corresponding to the defective portion 26.

According to this manufacturing method, conditions such as heating temperature, heating time, or exhaust speed, and melting temperature or decomposition temperature or oxidation rate of the material forming each member are appropriately selected and optimum conditions are set. This allows the dielectric layer 20 and the auxiliary discharge electrode 22 to be prepared without preparing any special material or process.
Can be formed, and the manufacturing can be simplified. On the other hand, in forming the auxiliary discharge electrode 22, the auxiliary discharge electrode 22
The metal particles 30, which are the material of, are inevitably buried and mixed in the dielectric layer 20, but as described above, the lead wires 12, 12
Since the defect portion 26 that crosses the gap is formed, the lead wire 12,
The insulation between the 12 can be maintained.

Further, the defective portion 26 forms a minute gap, and as a result, the effect of further improving the surge response performance is produced. That is, since the conductive metal particles 30 are mixed in the dielectric layer 20, the dielectric layer 20 itself becomes conductive to some extent, and therefore the electric field strength in the defect portion 26 (small gap) at the time of applying a surge. Becomes extremely high, and a large amount of electrons and ions are emitted. And
Since this functions as a trigger, the early generation of the air discharge in the auxiliary discharge gap 24 and the early generation of the arc discharge in the discharge gap 16 are realized.

Further, a concave portion 28 is formed in a portion of the inner surface of the airtight container 18 corresponding to the defective portion 26, and the creepage distance between the lead wires 12 and 12 is increased by that much, resulting in improvement of life characteristics against repeated surge application. Can be achieved.

The defective portion 26 does not necessarily have to be formed by irradiating a laser beam, but can be formed by removing a part of the dielectric layer 20 using a means such as cutting or etching. Further, the defective portion 26 is at least the lead wire 1.
It suffices if it is interposed between 2 and 12, and it is not always necessary to form it over a wide range as shown in FIGS. 1 and 2.

[0027]

As described above, in the discharge type surge absorbing element according to the present invention, the defective portion formed by removing a part of the dielectric layer is interposed at least between the lead wires on the inner surface of the hermetic container. Therefore, even if metal particles are buried and mixed in the dielectric layer at the time of forming the auxiliary discharge electrode and the insulation resistance of the dielectric layer itself is lowered, the insulation between the lead wires is maintained. Therefore, when a surge is applied, the creeping corona discharge is maintained between the lead wires due to the decrease in the insulation resistance of the dielectric layer, and as a result, arc discharge cannot be generated in the discharge gap, which is a problem that the conventional technology has. Can be effectively resolved.

Further, according to the method of manufacturing a discharge type surge absorber of the present invention, after forming a hermetic container by sealing a glass tube or the like, a laser beam is irradiated from the outside to form on the inner surface of the hermetic container. Since it is configured to evaporate a part of the dielectric layer, it is possible to form the defect portion very easily, and particularly, it is possible to form the defect portion even for the existing discharge type surge absorbing element. Can contribute to effective utilization of.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a discharge type surge absorber according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view showing a space between lead wires of the discharge type surge absorber.

FIG. 4 is a vertical sectional view showing a conventional discharge type surge absorber.

FIG. 5 is an enlarged view showing a space between lead wires of a conventional discharge type surge absorbing element.

[Explanation of symbols]

 10 Discharge type surge absorber 12 Lead wire 14 Discharge electrode 16 Discharge gap 18 Airtight container 20 Dielectric layer 22 Auxiliary discharge electrode 24 Auxiliary discharge gap 26 Defect 28 Depression

Claims (4)

[Claims] 1. A plurality of discharge electrodes connected to lead wires are arranged to face each other in an airtight container filled with a discharge gas to form a discharge gap between the discharge electrodes, and the lead wires of each discharge electrode are hermetically sealed. A member housed in the airtight container, which is led out to the outside of the container, forms a dielectric layer having good creeping discharge characteristics between at least the lead wires on the inner surface of the airtight container, and at least the surface of the dielectric layer. A large number of auxiliary discharge electrodes formed by using the metal forming the
In a discharge-type surge absorbing element, wherein an auxiliary discharge gap smaller than the discharge gap is formed between the lead wires, a part of the dielectric layer is removed at least between the lead wires on the inner surface of the hermetic container. Discharge type surge absorbing element, characterized in that a defective portion is interposed. 2. The discharge type surge absorber according to claim 1, wherein a portion of the inner surface of the airtight container corresponding to the defective portion is a recess. 3. The discharge type surge absorber according to claim 1, wherein the defective portion is formed in a band shape having a width of 50 to 300 μm that crosses between the lead wires. 4. A plurality of discharge electrodes connected to lead wires are arranged to face each other in an airtight container filled with discharge gas to form a discharge gap between the discharge electrodes, and the lead wires of each discharge electrode are hermetically sealed. A member housed in the airtight container, which is led out to the outside of the container, forms a dielectric layer having good creeping discharge characteristics between at least the lead wires on the inner surface of the airtight container, and at least the surface of the dielectric layer. A large number of auxiliary discharge electrodes formed by using the metal forming the
An auxiliary discharge gap smaller than the discharge gap is formed between the lead wires, and a defect formed by removing a part of the dielectric layer is interposed between at least the lead wires on the inner surface of the airtight container. A method of manufacturing a discharge type surge absorbing element comprising: a hermetic container made of glass, and a part of the dielectric layer formed on the inner surface of the hermetic container by irradiating a laser beam from the outside of the hermetic container. A method of manufacturing a discharge type surge absorbing element, characterized in that the defect portion is formed by evaporation.