JP3161498B2 - Discharge type surge absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone, a facsimile,
The present invention relates to a discharge surge absorber having a function of absorbing high-frequency noise in addition to a function of absorbing surge voltage applied to electronic components for communication devices such as telephone exchanges and modems. More specifically, the present invention relates to a counter electrode type surge absorber in which both ends of the tube are hermetically sealed by a pair of counter electrodes forming a discharge gap inside the tube.

[0002]

2. Description of the Related Art Conventionally, as a surge absorber of this type, an airtight container is formed by sealing both ends of a ceramic tube with a sealing cap via a sealing member, and at least a discharge gap is provided in the airtight container. Disclosed is a surge absorbing element in which opposing electrodes are accommodated, a sealing cap is formed of a material having a coefficient of thermal expansion matching that of the ceramic tube and the sealing member, and the electrodes are formed of a material having good discharge characteristics. (Jpn. Showa 61-63787). The ceramic tube of this surge absorbing element is formed of an insulating ceramic material such as forsterite. In the surge absorbing element configured as described above, when an instantaneous surge voltage such as a lightning surge is applied between the electrodes, an arc discharge occurs between the electrodes based on a discharge starting voltage determined by a discharge gap, and a surge occurs. The voltage can be absorbed. Further, in this surge absorbing element, the sealing operation can be performed easily, the reliability of the sealing is improved, and a longer life and a lower cost can be manufactured.

[0003]

However, in the above conventional surge absorbing element, since the ceramic tube is made of an insulating ceramic material such as forsterite, even if high-frequency noise enters electronic equipment, the noise is absorbed. When it is necessary to absorb high-frequency noise, a noise filter must be used separately from the surge absorbing element, which increases the number of electronic components, increases manufacturing costs, and reduces the size of electronic devices. It was an obstacle to the development. Further, the conventional surge absorbing element has difficulty in responding to a very steep surge at a sufficiently high speed, and has a drawback that the residual voltage increases.

An object of the present invention is to provide a discharge type surge absorber having a high frequency noise absorbing function in addition to a surge absorbing function without increasing the number of parts.
Another object of the present invention is to provide a discharge type surge absorber having good responsiveness to a surge impulse.

[0005]

A configuration of the present invention for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment. According to the present invention, a pair of sealing electrodes 12 and 13 are sealed opposite to each other at both ends of the ceramic tube 11 so as to seal an inert gas inside the ceramic tube 11, and a pair of sealing electrodes 12 and This is an improvement of the discharge type surge absorber 10 in which a discharge gap 14 is formed between 13. Its characteristic configuration is that the ceramic tube 11 has a relative dielectric constant of at least 10
A lead-based relaxor material or a barium titanate-based material
It has a function of absorbing high-frequency noise and is composed of a pair of sealing electrodes.
The poles 12 and 13 are almost equal to the coefficient of thermal expansion of the ceramic tube 11
Where it is made of a new metal .

Hereinafter, the present invention will be described in detail. The discharge type surge absorber 10 of the present invention is an arrester type, that is, a counter electrode type surge absorber, and a pair of sealing electrodes 12 facing each other at both ends of a ceramic tube 11 as shown in FIG.
13 at a predetermined interval, that is, a predetermined discharge gap 1
4, a pair of sealing electrodes 12 and 13 are sealed by filling an inert gas into a ceramic tube 11. The ceramic tube 11 has a relative dielectric constant of at least 10
However, a dielectric material having a relative dielectric constant of a lead-based relaxor material and a barium titanate-based material shown in Table 1 is preferable. These dielectrics are the same material as the dielectric used for the ceramic capacitor.

[0007]

[Table 1]

The PFW in Table 1 is Pb (Fe, W) O ₃ ,
PFN is Pb (Fe, Nb) O ₃ , and PZN is Pb (Z
n, Nb) O ₃ , PT is PbTiO ₃ , PMN is Pb
(Mg, Nb) O ₃ , PNW is Pb (Nb, W) O
₃ , BT for BaTiO ₃ , PMW for Pb (Mg, W)
The O _3, PZT and the _{Pb (Zn, Ti) O 3} , PLiFW
Is Pb (Li, Fe, W) O ₃ , and BCZT is (Ba,
Ca) (Zr, Ti) O ₃ , PG is Pb ₅ Ge ₃ O
₁₁ , BTS with Ba (Ti, Si) O ₃ , BSCZT
Is (Ba, Sr, Ca) (Zr, Ti) O ₃ , CZ is CaZrO ₃ , and BSCT is (Ba, Ca) (Zr, T
i) O ₃ and G each represent a glass composition.

The sealing electrodes 12 and 13 are formed of a metal having substantially the same thermal expansion coefficient as that of the ceramic tube 11 in order to prevent cracks due to thermal contraction of the ceramic tube 11 during sealing. 52 wt% iron for the sealing electrodes 12 and 13
-42 wt% nickel-6 wt% chromium alloy, 58 w iron
A t% -nickel 42 wt% alloy (hereinafter, referred to as a 42 alloy) and a copper clad material, Kovar, and the like are used. The 42 alloy and copper clad material is produced by a cladding method in which a copper thin film is adhered to one or both surfaces of a 42 alloy plate and mechanically rolled at a high temperature.

The sealing electrodes 12 and 13 are composed of sealing portions 12 a and 13 a which are sealed on the end face of the ceramic tube 11, and sealing portions 12 and 13.
a, 13a and electrode part 12 formed integrally with each other
b, 13b. The sealing portions 12a and 13a and the electrode portions 12b and 13b are simultaneously formed by forging, casting, cutting, or the like using any of the above metals. Alternatively, the sealing electrode may be formed by punching the clad material into a disc and then drawing. Alternatively, the sealing portion and the electrode portion may be separately formed and then formed by welding the electrode portion to the sealing portion. Further, a pair of sealing electrodes may be formed in a columnar shape. In this case, these electrodes are inserted into the ceramic tube while forming a predetermined discharge gap, and at the same time, after sealing an inert gas, are sealed to the ceramic tube.

The discharge gap 14 is 10 μm to 1 mm or less, preferably 10 to 100 μm, and particularly preferably 30 μm.
５０50 μm. The gap 14 is determined by an abnormal voltage to be absorbed, that is, a magnitude of a discharge starting voltage. The inert gas sealed inside the ceramic tube 11 when sealing the sealing electrodes 12 and 13 is A
r, Ne, He, N ₂ , CO ₂ , SF _{6 and the} like. The inert gas is 0 to 3000 Torr, preferably 3 Torr.
00 to 1500 Torr, more preferably 800 to 13
Sealed at a pressure of 00 Torr. In addition, the sealing electrode 12,
13 is sealed to the ceramic tube by the brazing material 16. When the metallizing treatment is performed on the end surface of the ceramic tube 11 as the brazing material 16, Ag, Ag-Cu, Ag-Cu
-In, Ag-Cu-Pd, Au-Ni, Ag-Pd, etc. can be used. If the metallization is not applied to the end surface of the ceramic tube 11, Ti-Cu,
Ti-Ni, Zr-Cu, Zr-Fe, Ag-Cu-T
A brazing material such as i can be used.

[0012]

The surge absorber 10 shown in FIG. 1 is represented by an equivalent circuit as shown in FIG. In FIG. 3, reference numeral 31 denotes a surge absorbing circuit, reference numeral 32 denotes a capacitor circuit, and reference numerals 33 and 34 denote lead terminals. The surge absorbing circuit 31 mainly includes the discharge gap 14 and the pair of sealing electrodes 12 and 13 shown in FIG.
The capacitor circuit 32 includes a pair of sealing electrodes 12 and 13 and the ceramic tube 11. For the sake of simplicity, it is assumed that a surge voltage of a square wave A (FIG. 4) including a high-frequency component exceeding each discharge starting voltage Vs of the surge absorber 10 as shown in FIG. 1 is applied to the lead wire. If the surge absorber 10 comprises only the surge absorbing circuit 31 as in the prior art, an arc discharge occurs between the sealing electrodes 12, 13 based on the discharge starting voltage determined by the discharge gap 14, and the surge voltage is absorbed. You. That is, the rise in the same way steep and applied waveform as shown in waveform B of FIG. 4, and discharges the delay time t ₁ after reaching the same peak value as the applied waveform. If the surge absorber 10 is constituted only by the capacitor circuit 32, the surge absorber 10 has the same peak value as the applied waveform as shown in the waveform C according to the capacitance of the ceramic tube 11 between the sealing electrodes 12 and 13. Since the high frequency component of the applied surge voltage is absorbed by the capacitor circuit 32, the waveform becomes dull. In the present invention the surge absorber 10 is composed of the surge absorption circuit 31 and the capacitor circuit 32, but rises in the same manner as the waveform C as shown in the waveform D, and discharged from beyond the discharge starting voltage Vs delay at time t ₁ . As a result, the impulse discharge starting voltage of the surge absorber 10 of the present invention can be kept low.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. <Embodiment> The discharge type surge absorber 10 shown in FIGS. 1 and 2 was manufactured by the following method. First, the ceramic tube 11
Was prepared. The ceramic tube 11 is obtained by cutting a cylindrical body having an inner diameter of 3 mm and an outer diameter of 7 mm formed of a ceramic dielectric made of a lead-based relaxer material of PT-PMN into a length of 4 mm. Next, a pair of sealing electrodes 12 and 13 were prepared. These electrodes 12 and 13 are connected to the ceramic tube 11.
Sealing portions 12a and 13a to be sealed to the end faces of
Frustoconical electrode part 1 formed integrally with 2a, 13a
2b and 13b, and formed by forging Kovar.

A ceramic tube 11 is connected to a pair of sealing electrodes 12,
After firmly sandwiching with 13 and evacuating the air inside the ceramic tube 11, argon (Ar) is used instead as an inert gas.
A gas was introduced at a pressure of 600 Torr, and in this state, the outer peripheral edges of the sealing portions 12a and 13a of the sealing electrodes 12 and 13 and the outer peripheral edges of both ends of the ceramic tube 11 were brazed with an Ag brazing material 16, respectively. At this time, the sealing electrode 12,
The discharge gap formed between the thirteen electrode portions 12b and 13b was 50 μm.

Comparative Example A comparative example was a surge absorber in which the ceramic tube of the above embodiment was formed of an alumina sintered body instead of the ceramic dielectric. Other configurations and dimensions are the same as those of the embodiment.

<Comparative Test and Evaluation> The relative permittivity, capacitance, discharge start voltage and impulse discharge start voltage of each of the surge absorbers of the embodiment and the comparative example were examined. The impulse discharge starting voltage of (1.2 × 50)
The measurement was performed by applying a standard lightning surge (pseudo surge) of 10 kV in μsec. The waveform is shown in FIG. The symbol E shown in FIG. 5A is the applied waveform, the symbol F shown in FIG. 5B is the waveform of the surge absorber of the comparative example, and the symbol G shown in FIG. 5C is the surge absorber of the example. 10 is a waveform of FIG.

[0017]

[Table 2]

As is clear from FIG. 5 and Table 2, the surge absorber of the comparative example having a small relative dielectric constant and a small capacitance has the following features.
As shown in FIG.
(B)), after reaching the discharge starting voltage Vs, discharged with a delay time t _1. On the other hand, in the surge absorber 10 of the embodiment, since the high frequency component is absorbed between the sealing electrodes 12 and 13 having a high relative dielectric constant and a large capacitance, the rising is not steep. Since the time t ₁ from when the discharge starting voltage Vs is reached to when the discharge is started is the same as in the comparative example, the wave front of the surge absorber 10 of the embodiment becomes slower and lower (FIG. 5C). As a result, the impulse discharge starting voltage of the surge absorber of the comparative example was 600 V, whereas the surge absorber 10 of the example was reduced to 500 V. Thereby, the response to the surge impulse was improved.

[0019]

As described above, according to the present invention, the ceramic tube of the conventional surge absorbing element is made of a ceramic dielectric, so that the high frequency noise can be obtained in addition to the surge absorbing function without increasing the number of parts. Can be provided. This reduces the cost of manufacturing and assembling electronic components, and contributes to downsizing of electronic devices. In addition, there is an advantage that the response waveform to the surge impulse is improved because the response waveform is not steep.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line HH of FIG. 2 showing a discharge type surge absorber according to one embodiment of the present invention.

FIG. 2 is a perspective view of the surge absorber.

FIG. 3 is an equivalent circuit diagram of the surge absorber.

FIG. 4 is a diagram showing a situation when a square wave surge voltage is applied to each of the discharge type surge absorbers of the present invention and a comparative example.

FIG. 5 is a diagram corresponding to FIG. 4, showing a situation when a standard lightning surge voltage is applied to each of the discharge type surge absorbers of the example and the comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Discharge type surge absorber 11 Ceramic tube 12, 13 Sealing electrode 14 Discharge gap

Continuation of front page (56) References JP-A-3-141572 (JP, A) JP-A-6-140210 (JP, A) JP-A-6-61018 (JP, A) JP-A-4-6190 (JP) , U) Japanese Utility Model Showa 60-137424 (JP, U) Japanese Utility Model Hei 9-92689 (JP, U) Japanese Patent Publication No. 1-36676 (JP, B2) Japanese Utility Model Hei 3-3995 (JP, Y2) Japanese Utility Model 6-16452 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01T 1/00-4/20

Claims (1)

(57) [Claims] A pair of sealing electrodes (12, 13) are sealed at both ends of the ceramic tube (11) so as to seal an inert gas inside the ceramic tube (11), And a discharge type surge absorber (10) in which a discharge gap (14) is formed between the pair of sealing electrodes (12, 13), wherein the ceramic tube (11) has a relative dielectric constant of at least 10.
Of lead-based relaxor material or barium titanate-based material
The ceramic tube (11) has a function of absorbing high-frequency noise by being formed of a ceramic dielectric formed by the above-mentioned method, and the pair of sealing electrodes (12, 13) is formed of the ceramic tube (11).
A discharge type surge absorber characterized by being formed of a metal having substantially the same thermal expansion coefficient .