JPH08138828A - Manufacture of discharge type surge absorbing element and discharge type surge absorbing element - Google Patents

Abstract

PURPOSE: To ensure formation of a layer and an auxiliary discharge electrode as desired without relying on gaps incidentally caused in the surface of an emitter layer by providing an exposure area on the surface of an electrode base, where no emitter layer exists, to supply material for the layer and the auxiliary discharge electrode therefrom. CONSTITUTION: A nickel electrode base 12 has barium carbonate deposited at the end 12a. It is arranged in an air-tight container 18 formed of dielectric to give heating and exhausting treatment thereto, so that an emitter layer 13 formed of barium oxide can be formed only at the end 12a of the electrode base 12 which has the base end 12b formed as an exposure area 12c where no emitter layer 13 exists. The surfaces of the emitter layer 13 and the exposure area 12c are melted and spattered to form a layer 20, which is formed of a mixture of barium oxide as dielectric and nickel oxide as semiconductor, and an auxiliary discharge electrode 22, formed of nickel, on the inner face of the air-tight container 18.

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 that absorbs a surge by utilizing a discharge phenomenon in a discharge gap enclosed in an airtight container, and is particularly suitable for air discharge in the discharge gap. The present invention relates to a discharge type surge absorbing element having improved surge response performance by taking various trigger means.

[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, the airtight container is made of a dielectric material, and a layer body made of a mixture of a dielectric material and a semiconductor is formed on the inner surface of the airtight container using a part of the constituent members housed in the airtight container. By arranging a number of auxiliary discharge electrodes on the surface of the layered body in a scattered manner by using a part of the constituent members housed in the airtight container,
There are technologies for improving the surge response performance.

As an example thereof, the discharge type surge absorber shown in FIG. 3 has an emitter layer 52 on the surface of a rod-shaped electrode base 52a.
Lead wires 53, 53 are connected to the lower ends of a pair of discharge electrodes 52, 52 formed by depositing b, and the lead wires 53, 53 are arranged in parallel with each other with a predetermined discharge gap 54 formed between them to form a glass tube. The airtight container 56 is sealed together with a predetermined discharge gas, the lead wires 53, 53 are led out of the airtight container 56, and the discharge electrode 52 of the discharge electrode 52 is provided at least between the lead wires 53, 53 on the inner surface of the airtight container 56. A layered body 60 formed using a part of it is applied. The layer body 60 is connected in parallel with the discharge gap 54 via lead wires 53, 53. Further, as shown in FIG. 4, a large number of conductive granular or lump auxiliary discharge electrodes 62 formed of the discharge electrode 52 as a material are arranged on the surface of the layer body 60, and lead wires 53 and Auxiliary discharge electrode
62 and the auxiliary discharge electrodes 62, the discharge gap 54
The auxiliary discharge gap 64 is much narrower than the above.

The discharge type surge absorbing element 50 is specifically manufactured as follows. First, a nickel electrode substrate 52a to which a lead wire 53 is connected is dipped in a bath filled with an emitter material such as barium carbonate to deposit the emitter material on the surface, and then inserted into the tube through one end opening of the glass tube. Then, the opening of the glass tube is melted and crushed to fix the middle portion of the lead wire 53 to the fused portion of the glass tube. Next, an exhaust device is connected to the other end opening of the glass tube, these are placed in a high-frequency coil to perform high-frequency heating, and the inside of the glass tube is exhausted. By this heat treatment, barium carbonate as an emitter material is thermally decomposed and an emitter layer 52b made of barium oxide is formed on the surface of the electrode base 52a to complete the discharge electrode 52. Since a gap is formed in the emitter layer 52b due to uneven coating of the emitter material and cracks generated during thermal decomposition, the surface of the electrode substrate 52a corresponding to the gap in the emitter layer 52b is subjected to the heat treatment. Melt by. And, by the depressurizing action in the glass tube accompanying the exhaust treatment,
The barium oxide and the molten nickel of the electrode substrate scatter around and adhere to the inner surface of the glass tube (airtight container 56) in a layered manner.

At this time, since air remains in the glass tube in the early stage of the exhaust process and the molten and scattered nickel is oxidized on the way, nickel oxide as a semiconductor and a dielectric are formed on the inner surface of the glass tube. Forming a layered body 60 of a mixture of barium oxide. Next, when air disappears in the glass tube as the exhaust process progresses, the molten and scattered nickel adheres to the surface of the layered body 60 without being oxidized, and the granular or lumped auxiliary discharge electrode 62 having conductivity is provided. Will be formed.

However, since the permittivity of the glass forming the hermetic container 56 and the permittivity of barium oxide contained in the layered body 60 are different from each other, a charge is easily held between the two dielectrics. In addition, since barium oxide exerts a high photoelectric effect, a large amount of electric charge is accumulated between the layer body 60 and the inner surface of the airtight container 56. Therefore, the lead wire 5
When a surge more than the rated value is applied to the discharge type surge absorbing element 50 via 3, 53, the electric charge is immediately transferred from the one lead wire 53 to the other via the nickel oxide in the layer body 60 by the tunnel effect of the semiconductor. To the lead wire 53 side, current flows between both lead wires 53, 53, and absorption of the surge is started. At the same time, a creeping corona discharge is generated between the layer body 60 and the discharge gas, and the surge is also absorbed through the creeping corona discharge. Then, electrons and ions are released into the airtight container 56 through the movement of charges in the layer body 60 and the surface corona discharge on the surface of the layer body 60, and the priming effect of the electrons and ions causes the surface to creep in the surface in a short time. The corona discharge is transferred to the auxiliary discharge gap 64 to generate the air discharge, the air discharge is transferred to the discharge gap 54, and finally the surge is absorbed through the large current of the arc discharge.

That is, this discharge type surge absorbing element 50
Is to quickly absorb surges through the electric current in the layer body 60 and the creeping corona discharge on the surface of the layer body 60,
The energization and creeping corona discharge are used as triggers for the air discharge in the auxiliary discharge gap 64, and the air discharge in the auxiliary discharge gap 64 is the main discharge (arc discharge) in the discharge gap 54.
It is intended to improve the surge response performance of the device as a whole by using it as a trigger of the. In particular, the auxiliary discharge gap 64 has a much smaller gap length than the discharge gap 54, and the distance from the layered body 60 is also shorter.
Air discharge is generated in the auxiliary discharge gap 64 in a shorter time. Moreover, since this air discharge emits much more electrons and ions than the creeping corona discharge, the creeping corona discharge on the surface of the layered body 60 and the discharge gap 54
By interposing the aerial discharge in the auxiliary discharge gap 64 with the main discharge in, the generation of the main discharge in the discharge gap 54 can be further speeded up.

[0008]

The layer body 60 and the auxiliary discharge electrode 62 are made of a part of the discharge electrode 52 housed in the airtight container 56 as described above, and the discharge type surge absorbing element Since it is formed using a normal manufacturing process, it is possible to simplify the manufacturing process and reduce the number of materials. However, in this conventional manufacturing method, since nickel composing the electrode base 52a is melted and scattered from the gap between the emitter layers 52b that is accidentally generated, there is a possibility that the amount of nickel that is melted and scattered varies. Yes, in extreme cases, the layered body 60 cannot be formed with the necessary components (mixing ratio with barium oxide), thickness and area, or the auxiliary discharge electrode.
It was possible that 62 could not be distributed with sufficient density. Further, in the discharge electrode 52, the discharge mainly occurs at the tip portion, and although the emitter layer 52b is originally required to be formed only at the tip portion, the discharge type electrode manufactured by the conventional manufacturing method is used. In the surge absorbing element 50, the emitter layer 52b is formed over substantially the entire area of the electrode base 52a, which consumes a relatively expensive emitter material more than necessary, which increases the manufacturing cost. It will be.

The present invention has been made in view of the above-mentioned conventional problems, and a certain amount of a substance is applied when a layered body and an auxiliary discharge electrode are formed by melting and scattering a part of the substance constituting the electrode substrate. To realize a method of manufacturing a discharge type surge absorbing element capable of reliably melting and scattering to form a layered body having necessary components, thickness and area, and an auxiliary discharge electrode having sufficient distribution density. It is in. Another object of the present invention is to realize a discharge-type surge absorption element that can be manufactured at low cost by refraining from using unnecessary emitter materials.

[0010]

In order to achieve the above-mentioned object, a method of manufacturing a discharge type surge absorbing element according to the present invention applies an emitter material to the surface of a pair of rod-shaped electrode bases to which lead wires are connected. , The two electrode substrates are housed in an airtight container made of a dielectric material while facing each other with a discharge gap therebetween,
The middle part of each lead wire is fixed to the airtight container and the ends are led out to the outside, the exhaust treatment in the airtight container is performed while the heat treatment is performed on the whole, and the emitter material is thermally decomposed by the heat treatment. An emitter layer made of a dielectric is formed on the surface of the electrode substrate, the surface of the electrode substrate is melted, and the constituent substance of the emitter layer and the constituent substance of the electrode substrate are scattered around by the depressurizing action by the exhaust treatment, Of the scattered constituent substances of the electrode substrate, those which are oxidized and become semiconductor during the scattering are adhered to the inner surface of the airtight container together with the constituent substances of the emitter layer, thereby forming a dielectric between at least lead wires on the inner surface of the hermetic container. A layered body made of a mixture of a metal and a semiconductor is formed, and the constituent substances of the electrode substrate that are not oxidized during the scattering are directly attached to at least the surface of the layered body. A plurality of granular or lumped auxiliary discharge electrodes, thereby forming an auxiliary discharge gap smaller than the discharge gap between the lead wires, and then filling the discharge gas into the airtight container to form the airtight container. In a method of manufacturing a discharge type surge absorption element for hermetically sealing, an emitter layer is formed by adhering the above-mentioned emitter material to a tip end side of an electrode substrate, and a side of a surface of the electrode substrate connected to a lead wire is an emitter layer. The exposed portion does not exist, and the surface of the exposed portion is melted and scattered through the heating and exhaust treatment, whereby the layer body and the auxiliary discharge electrode are formed.

Further, in the discharge type surge absorbing element according to the present invention, a pair of discharge electrodes formed by forming an emitter layer on the surface of a rod-shaped electrode base to which lead wires are connected are arranged to face each other with a discharge gap. This is stored in an airtight container made of a dielectric together with a discharge gas, the middle part of each lead wire is fixed to the airtight container, and the end portion is led out to the outside, and at least between both lead wires on the inner surface of the airtight container, A layered body made of a mixture of a dielectric and a semiconductor is formed by using the constituent material of the emitter layer and the electrode substrate as a material, and is formed on the surface of the layered body by the material of the electrode substrate. In a discharge-type surge absorption element comprising a large number of granular or lumped auxiliary discharge electrodes arranged in a scattered manner to form an auxiliary discharge gap narrower than the discharge gap between the lead wires,
The emitter layer is formed on the tip side of the electrode substrate,
It is characterized in that an exposed portion where the emitter layer does not exist is formed on the side of the surface of the electrode substrate where the lead wire is connected to the lead wire. It is desirable that the exposed portion occupy one-third or more of the length of the entire electrode substrate. It is desirable that the electrode substrate and the auxiliary discharge electrode are made of nickel, the emitter layer is made of barium oxide, and the layer body is made of a mixture of nickel oxide and barium oxide.

[0012]

In the above-mentioned manufacturing method, the exposed portion where the emitter layer does not exist is provided on the surface of the electrode substrate (on the side where the lead wire is connected) without forming the emitter layer on the entire surface of the electrode substrate. Since the material for forming the layered body and the auxiliary discharge electrode is supplied from the exposed portion, the layered body and the auxiliary discharge electrode can be formed as intended without depending on the gap that is accidentally generated on the surface of the emitter layer. It can be reliably formed. Further, since the discharge type surge absorption element obtained by this manufacturing method has the emitter layer formed only on the tip side of the electrode substrate, the amount of relatively expensive emitter material used can be minimized. As a result, a reduction in manufacturing cost can be realized.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a vertical cross-sectional view showing a discharge type surge absorber 10 according to an embodiment of the present invention. This discharge type surge absorbing element 10 is composed of a pair of electrode bases 12, 12 having tip portions 12a, 12
The discharge layer 1 is formed by depositing the emitter layers 13, 13 on the a-side surface.
4 and 14, and lead wires 15 and 15 made of Dumet wire (copper-coated iron-nickel alloy wire) or 42-6 alloy wire are connected to the base end portions 12b and 12b of the electrode bases 12 and 12, respectively. Discharge electrode 1
4 and 14 are arranged in parallel at a predetermined distance and the discharge gap 16
Of the discharge electrodes 14 and 14 and sealed in an airtight container 18 formed by processing a glass tube.
5, 5 are led out of the airtight container 18. The electrode base 12
Is formed by processing a metal such as nickel having excellent conductivity into an elongated rod shape or a plate shape. Further, the emitter layer 13 is
It is made of an emitter material having a small work function, such as barium oxide or lanthanum hexaboride, and is formed with the intention of reducing the discharge starting voltage and improving the sputtering resistance.

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 a dielectric material such as barium oxide is formed in the lower portion of the inner surface of the airtight container 18. A layer body 20 made of a mixture with a semiconductor such as nickel oxide is deposited and formed so as to connect at least both the lead wires 15 and 15. Further, as is apparent from FIG. 2 which shows an enlarged contact portion between the lead wires 15 and 15 and the inner surface of the airtight container 18, the auxiliary discharge electrode 22 made of granular or massive nickel or the like is scattered on the surface of the layer body 20. A large number of dots are arranged in a dot pattern, and between the lead wires 15 and the auxiliary discharge electrodes 22, and between the auxiliary discharge electrodes 22 and 22, an auxiliary discharge gap 24 that is much smaller than the discharge gap 16 is formed. There is.

Since the dielectric constant of the glass forming the hermetic container 18 and the dielectric constant of the barium oxide or the like contained in the layered body 20 are different from each other, it is considered that electric charges are easily held between the two dielectrics. In addition, since barium oxide and the like exert a high photoelectric effect, a large amount of electric charge is accumulated between the layer body 20 and the inner surface of the airtight container 18. Therefore, the lead wire
When a surge of more than the rated value is applied to the discharge type surge absorbing element 10 via 15 and 15, the charges are immediately transferred from one lead wire 15 through the nickel oxide in the layer body 20 due to the tunnel effect of the semiconductor. It moves to the other lead wire 15 side, current flows between both lead wires 15 and 15, and absorption of the surge is started. At the same time, a creeping corona discharge is generated between the layer body 20 and the discharge gas, and the surge is also absorbed through the creeping corona discharge. Then, electrons and ions are released into the airtight container 18 through the movement of charges in the layer body 20 and the surface corona discharge on the surface of the layer body 20, and by the priming effect of the electrons and ions, the surface of the layer surface is shortened. The corona discharge is transferred to the auxiliary discharge gap 24 to generate the air discharge, the air discharge is transferred to the discharge gap 16, and finally the surge is absorbed through the large current of the arc discharge.

Next, an example of a method of manufacturing the discharge type surge absorber 10 will be described. First, lead wires 15 and 15
On the surface of the electrode substrates 12, 12 made of nickel connected to
Deposit an emitter material consisting of barium carbonate. At this time, the emitter material is not attached to the entire surface of the electrode base 12, but is attached only to the tip end 12a side of the electrode base 12, and the base end 12b side of the electrode base 12 (connecting portion to the lead wire 15). Side) is exposed. The range where the emitter material is attached is preferably within two-thirds of the entire length of the electrode base 12 from the tip portion 12a of the electrode base 12.

Next, the lead wires 15 and 15 are aligned in the same direction and held by an aligning jig, the electrode substrates 12 and 12 are opposed to each other at a predetermined interval, and this is inserted into a glass tube whose both ends are open. The lead wires 15 and 15 are housed so that the lower end portions of the lead wires 15 and 15 project outward from one end opening of the glass tube. Then, the opening portion of the glass tube is heated and melted by a gas flame, the molten portion is crushed inward by a pincher and sealed, and the middle portions of the lead wires 15 and 15 are fixed to the sealed portion of the glass tube. At the same time, the lower ends of the lead wires 15 and 15 are led out of the glass tube. At this time, the exposed portions 12c, 12 of the electrode substrates 12, 12 are heated by heating the glass tube in the air.
c is oxidized to form nickel oxide on the surface.

Next, an exhaust device is connected to the other end opening of the glass tube, and these are placed in a high frequency coil for high frequency heating, and the inside of the glass tube is exhausted. By this heat treatment, barium carbonate as an emitter material is thermally decomposed and the emitter layers 1 made of barium oxide are formed on the surfaces of the electrode substrates 12 and 12.
3 and 13 are formed, and the discharge electrodes 14 and 14 are completed. At the same time, by this heat treatment, the exposed portions 12c, 12c of the electrode substrate are
The surface of the melts. Then, due to the depressurizing action in the glass tube accompanying the exhaust treatment, the barium oxide of the emitter layers 13 and 13, the nickel oxide formed on the surfaces of the exposed portions 12c and 12c of the electrode substrate in the previous step, and the molten electrode substrate. 1
2, 12 nickel scatters around and is deposited in layers on the inner surface of the glass tube.

At this time, since the residual air concentration in the glass tube is high at the beginning of the exhaust process, the molten nickel from the exposed portions 12c, 12c of the electrode base body is oxidized during the scattering, so that the inner surface of the glass tube is Is a layered body composed of a mixture of nickel oxide as a semiconductor and barium oxide as a dielectric 20
Are deposited and formed. If the heating is further continued, the residual air concentration in the glass tube decreases as the exhaust process progresses,
Finally, the scattered nickel is not oxidized.
Therefore, if this heating operation is terminated when the nickel that is not oxidized adheres to the surface of the layered body 20 on the scattering points, as shown in FIG. 2, the granular or lumped auxiliary discharge electrode 22 having conductivity is formed. However, many are arranged on the surface of the layered body 20. In addition, the lead wire 15 and the auxiliary discharge electrode 22 are also provided.
A large number of auxiliary discharge gaps 24 are formed between the auxiliary discharge electrodes 22, 22.

By the exhaust treatment, residual air, carbon dioxide by decomposition of barium carbonate, and impure gas emitted from the glass tube itself or a member housed in the glass tube are completely removed to bring the inside of the glass tube into a high vacuum state. After that, filling the discharge gas, further heating the other end opening of the glass tube,
This is melted and sealed off to complete the airtight container 18.

When the base end portions 12b, 12b of the electrode bases come into contact with the inner surface of the sealed portion of the airtight container 18 (glass tube), the heat of the electrode bases 12, 12 is conducted to the airtight container 18 and heated. Since the efficiency may decrease and the exposed portions 12c, 12c of the electrode base body may not be effectively melted / scattered, between the base end portions 12b, 12b of the electrode base body and the inner surface of the sealed portion of the airtight container 18, As shown, it is desirable to secure a constant distance D.

According to this manufacturing method, conditions such as heating temperature, heating time, or evacuation rate, and melting temperature or decomposition temperature or oxidation rate of the materials forming the discharge electrodes 14, 14 are appropriately selected, and optimum conditions are selected. By setting, the layer body 20 and the auxiliary discharge electrode can be prepared without preparing a special material or process.
22 and the auxiliary discharge gap 24 can be formed, and the manufacturing can be simplified. In setting these conditions, it is necessary to take particular care so that the nickel oxide forming the layered body 20 is successfully made into a semiconductor.

Further, the emitter material is adhered only to the tip end portions 12a, 12a of the electrode base, and the base end portions 12b, 12 of the electrode base body are adhered.
Since the b side is exposed from the beginning, it is easy to control the amount of nickel that is melted and scattered, and it is easy to secure the composition, thickness and area of the layer body 20 or the distribution density of the auxiliary discharge electrode 22 above a certain level. Becomes

Further, by forming the emitter layers 13 and 13 only on the tips 12a and 12a side of the electrode substrate, not only the emitter material can be saved but the manufacturing cost can be reduced, but also the surge response performance can be improved. Can also be achieved.
That is, when the elongated rod-shaped electrode bases 12 and 12 are adopted and the lead wires 15 and 15 are connected to the base end portions 12b and 12b of the electrode bases 12 and 12, the tip end portion 12 of the electrode base body 12 is caused by the edge effect.
The electric field strength between a and 12a becomes the strongest, and discharge is most easily generated between the two. Therefore, by forming the emitter layers 13, 13 having a relatively small work function and a function of lowering the discharge start voltage only on the tip portions 12a, 12a of the electrode base, the emitters are dazzled over the entire surface of the electrode base. Compared with the case where layers are formed, the tip portions 12a, 12 of the electrode base body are
The discharge start during the period a is further promoted.

[0025]

In the method of manufacturing a discharge type surge absorbing element according to the present invention, the exposed portion having no emitter layer is provided on the surface of the electrode base without forming the emitter layer on the entire surface of the electrode base. Since the material for forming the layered body and the auxiliary discharge electrode is supplied from the exposed portion, the layered body and the auxiliary discharge as intended without depending on the gap that is accidentally formed on the surface of the emitter layer. The electrodes can be reliably formed. Further, since the discharge type surge absorption element obtained by this manufacturing method has the emitter layer formed only on the tip side of the electrode substrate, the amount of relatively expensive emitter material used can be minimized. As a result, a reduction in manufacturing cost can be realized.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a discharge type surge absorber according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a connecting portion between the lead wire of the discharge type surge absorber and the inner surface of the airtight container.

FIG. 3 is a vertical cross-sectional view showing a conventional discharge type surge absorber.

FIG. 4 is an enlarged cross-sectional view showing a connecting portion between a lead wire of a conventional discharge type surge absorber and an inner surface of an airtight container.

[Explanation of symbols]

 10 Discharge type surge absorber 12 Electrode base 12a Tip of electrode base 12b Base end of electrode base 12c Exposed part 13 Emitter layer 14 Discharge electrode 15 Lead wire 16 Discharge gap 18 Airtight container 20 Layered body 22 Auxiliary discharge electrode 24 Auxiliary discharge gap

Claims (4)

[Claims] 1. An emitter material is applied to the surface of a pair of rod-shaped electrode bases to which lead wires are connected, and both electrode bases are housed in an airtight container made of a dielectric material in a state of facing each other with a discharge gap, The middle part of each lead wire is fixed to the airtight container and the ends are led out to the outside, the exhaust treatment in the airtight container is performed while the heat treatment is performed on the whole, and the emitter material is thermally decomposed by the heat treatment. An emitter layer made of a dielectric is formed on the surface of the electrode substrate, the surface of the electrode substrate is melted, and the constituent substance of the emitter layer and the constituent substance of the electrode substrate are scattered around by the depressurizing action by the exhaust treatment, Among the scattered constituent substances of the electrode substrate, those which are oxidized and become semiconductor during the scattering are adhered to the inner surface of the airtight container together with the constituent substances of the emitter layer. At least, a layered body made of a mixture of a dielectric and a semiconductor is formed between the lead wires, and further, the constituent substances of the electrode substrate which are not oxidized during the scattering are directly attached to at least the surface of the layered body to form a large number of granular or lump-like particles. A discharge type which forms an auxiliary discharge electrode, thereby forming an auxiliary discharge gap smaller than the discharge gap between the lead wires, and then filling the discharge gas into the airtight container to hermetically seal the airtight container. In the method of manufacturing a surge absorbing element, the emitter material is adhered to the tip end side of the electrode base to form an emitter layer, and the surface of the electrode base is connected to the lead wire at an exposed portion where the emitter layer does not exist. And a heating and exhaust treatment to melt and scatter the surface of the exposed portion to form the layered body and the auxiliary discharge electrode. . 2. A hermetically sealed container made of a dielectric together with a discharge gas, and a pair of discharge electrodes each having an emitter layer formed on the surface of a rod-shaped electrode base to which a lead wire is connected, arranged to face each other across a discharge gap. The inside of each of the lead wires is fixed to an airtight container, and the ends are led out to the outside, and at least the lead wires on the inner surface of the airtight container are made of the constituent material of the emitter layer and the electrode substrate. Forming a layered body composed of a mixture of a dielectric and a semiconductor formed by
A large number of granular or lumped auxiliary discharge electrodes formed of the constituent material of the electrode substrate are arranged on the surface of the layered body in a scattered manner, and the auxiliary discharges are narrower than the discharge gap between the lead wires. In a discharge type surge absorbing element formed with a gap, the emitter layer is formed on the tip end side of the electrode base body, and the emitter layer does not exist on the surface of the electrode base body on the connection side side with the lead wire. A discharge type surge absorbing element characterized by being formed as an exposed portion. 3. The discharge type surge absorbing element according to claim 2, wherein the exposed portion occupies a length of 1/3 or more of the entire length of the electrode substrate. 4. The electrode base and the auxiliary discharge electrode are made of nickel, the emitter layer is made of barium oxide, and the layer body is made of a mixture of nickel oxide and barium oxide. Alternatively, the discharge type surge absorbing element described in 3 above.