JP6579443B2 - Surge protective element - Google Patents

Description

  The present invention relates to a surge protection element used for protecting various devices from a surge caused by a lightning strike and preventing accidents.

  Abnormal voltage (such as lightning surge or static electricity) on the part where electronic devices for communication devices such as telephones, facsimiles, modems, etc. are connected to communication lines, power lines, antennas or image display drive circuits such as CRTs, liquid crystal televisions and plasma televisions. A surge protection element is connected to a portion that is easily subjected to electric shock due to a surge voltage) in order to prevent destruction due to abnormal damage due to thermal damage or ignition of an electronic device or a printed circuit board on which the device is mounted.

Conventionally, as shown in Patent Documents 1 and 2, for example, an arrester type comprising a pair of protruding electrode portions protruding in a facing state from a pair of sealing electrodes, and having a discharge auxiliary portion formed on the inner peripheral surface of the insulating tube A surge protection element is described.
In these surge protection elements, the opposing surfaces of the pair of protruding electrode portions are arranged so as to be parallel to each other and orthogonal to the axis of the insulating tube.

JP 11-354244 A JP 2001-102148 A

The following problems remain in the conventional technology.
Usually, the projecting amount of the projecting electrode portion has a dimensional variation (error) within accuracy. For this reason, in the conventional structure in which the opposing surfaces of the pair of protruding electrode portions are arranged so as to be parallel to each other and perpendicular to the axis of the insulating tube, when the protruding amount varies, the variation amount is reflected as it is. There is a problem that the gap width between the protruding electrode portions of the first and second electrode portions fluctuates and the center value of the discharge start voltage Vs fluctuates.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a surge protection element that can suppress the fluctuation of the discharge start voltage Vs more than the conventional one even if the dimension of the protruding electrode part fluctuates. To do.

  The present invention employs the following configuration in order to solve the above problems. That is, the surge protection element according to the first aspect of the present invention includes an insulating tube and a pair of sealing electrodes that closes both end openings of the insulating tube and seals the discharge control gas inside. The sealing electrode has a pair of flange portions fixed in close contact with both end openings of the insulating tube, and a pair of protruding electrode portions that protrude inward from the pair of flange portions and face each other. The opposed surfaces of the pair of protruding electrode portions are parallel to each other and inclined with respect to the axis of the insulating tube.

  In the surge protection element of the present invention, the opposing surfaces of the pair of protruding electrode portions are parallel to each other and inclined with respect to the axis of the insulating tube. Therefore, when the angle between the axis and the opposing surface is θ, By reducing the displacement (error) of the dimension to a displacement of cos θ, the displacement of the discharge start voltage Vs can be made smaller than before.

A surge protection element according to a second invention is characterized in that, in the first invention, the tip of the protruding electrode portion is chamfered.
That is, in this surge protection element, since the tip end portion of the protruding electrode portion is chamfered, it is possible to suppress the concentration of the electric field at the corner portion of the tip end portion.

According to a third aspect of the present invention, there is provided the surge protection element according to the first or the second aspect, wherein the pair of discharge active layers are made of materials having higher electron emission characteristics than the material of the sealing electrode on the opposing surfaces of the pair of protruding electrode portions. The pair of discharge active layers are formed in the same shape at positions overlapping each other when viewed in the vertical direction of the pair of opposed surfaces.
That is, in this surge protection element, since the pair of discharge active layers are formed in the same shape at positions overlapping each other when viewed in the vertical direction of the pair of opposed surfaces, the pair of discharge active layers are directed in the opposite direction from the pair of discharge active layers. Thus, electrons can be emitted in the same manner.

A surge protection element according to a fourth invention is the surge protection element according to any one of the first to third inventions, further comprising a discharge auxiliary portion formed of an ion source material on an inner peripheral surface of the insulating tube, wherein the discharge auxiliary portion is , And formed in a region other than the region facing and adjacent to the tip portions of the pair of protruding electrode portions.
That is, in this surge protection element, since the discharge auxiliary portion is formed in a region other than the region facing and adjacent to the tip portions of the pair of protruding electrode portions, the tip portion of the protruding electrode portion is formed on the inner peripheral surface of the insulating tube. By disposing the discharge assisting portion so as to avoid the region facing the tip portion that is most susceptible to the influence of the discharge generated in the above, deterioration of the discharge assisting portion can be suppressed.

The present invention has the following effects.
That is, according to the surge protection element according to the present invention, since the opposing surfaces of the pair of protruding electrode portions are parallel to each other and inclined with respect to the axis of the insulating tube, the discharge due to the variation in the protruding amount of the protruding electrode portion. The displacement of the start voltage Vs can be made smaller than before.
Therefore, in the surge protection device according to the present invention, even if the gap width between the pair of projecting electrode portions varies due to the dimensional accuracy (error) of the projecting electrode, the variation in the center value of the discharge start voltage Vs is suppressed and the accuracy is improved. High discharge characteristics can be obtained.

It is sectional drawing of the axial direction which shows 1st Embodiment of the surge protection element which concerns on this invention. It is AA arrow sectional drawing of FIG. In 1st Embodiment, it is explanatory drawing which shows the relationship between the distance between the opposing surfaces in the direction perpendicular | vertical to an opposing surface, and the distance between the opposing surfaces in an axial direction. It is sectional drawing of the axial direction which shows 2nd Embodiment of the surge protection element which concerns on this invention. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 4.

  Hereinafter, a first embodiment of a surge protection element according to the present invention will be described with reference to FIGS. 1 to 3. In each drawing used for the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

As shown in FIGS. 1 and 2, the surge protection element 1 of this embodiment includes a pair of seals that close the insulating tube 2 and both ends of the insulating tube 2 and seal the discharge control gas inside. A stop electrode 3 is provided.
The pair of sealing electrodes 3 includes a pair of flange portions 4 fixed in close contact with both end openings of the insulating tube 2 and a pair of protruding electrode portions 5 protruding inward from the pair of flange portions 4 and facing each other. And have.
The opposed surfaces 5 a of the pair of protruding electrode portions 5 are parallel to each other and inclined with respect to the axis C of the insulating tube 2.

The tip portion 5b of the protruding electrode portion 5 is chamfered and the tip shape is rounded.
A pair of discharge active layers 6 are formed on the opposing surfaces 5 a of the pair of protruding electrode portions 5 with a material having higher electron emission characteristics than the material of the sealing electrode 3.
The pair of discharge active layers 6 are formed in the same shape at positions overlapping each other when viewed in the vertical direction of the pair of opposed surfaces 5a.
In the present embodiment, the discharge active layer 6 is formed in a circular shape.

Further, the surge protection element 1 of this embodiment includes a discharge auxiliary portion 7 formed of an ion source material on the inner peripheral surface of the insulating tube 2.
The discharge auxiliary portion 7 is formed in a region other than the region facing and adjacent to the tip portions 5b of the pair of protruding electrode portions 5. That is, in this embodiment, as shown in FIG. 2, among the four inner surfaces of the rectangular tubular insulating tube 2, the discharge auxiliary portions 7 are respectively formed on the pair of inner surfaces that do not face the tip portion 5b. Yes.

The discharge auxiliary portion 7 is a conductive material, and is formed of, for example, a carbon material.
The insulating tube 2 is a rectangular tube member made of a crystalline ceramic material such as alumina. The insulating tube 2 may be an amorphous tube such as lead glass.

The sealing electrode 3 is made of, for example, 42 alloy (Fe: 58 wt%, Ni: 42 wt%), Cu, or the like.
The sealing electrode 3 has a rectangular plate-like flange portion 4 that is fixed in close contact with an opening portion at both ends of the insulating tube 2 by a heat treatment using a conductive adhesive (not shown). The flange portion 4 and the protruding electrode portion 5 are integrally formed.

The conductive fusing material is formed of, for example, an Ag—Cu brazing material as a brazing material containing Ag.
The discharge control gas sealed in the insulating tube 2 is an inert gas or the like, for example, He, Ar, Ne, Xe, Kr, SF ₆ , CO ₂ , C ₃ F ₈ , C ₂ F ₆ , CF ₄ , H ₂ , the atmosphere, etc. and a mixed gas thereof are employed.

  The discharge active layer 6 contains, for example, Si and O as main components and includes at least one of Na, Cs, and C. The discharge active layer 6 is prepared, for example, by adding a cesium carbonate powder to a sodium silicate solution to apply a precursor to the surface of the sealing electrode 3, and then the sodium silicate softens against the precursor. The heat treatment is performed at a temperature equal to or higher than a temperature at which the cesium carbonate is melted and decomposed.

  In the surge protection device 1 of the present embodiment, as shown in FIG. 3, when the angle between the axis C and the facing surface 5a is θ, the distance L1 between the facing surfaces in the direction perpendicular to the facing surface 5a is the direction of the axis C. The distance L2 between the opposing surfaces becomes shorter by cos θ times. For this reason, when the distance L2 between the opposing surfaces in the direction of the axis C varies, the variation in the distance L1 between the opposing surfaces in the direction perpendicular to the opposing surface 5a is also reduced by cos θ.

  In this surge protection element 1, when an overvoltage or overcurrent enters, first, initial discharge is preferentially performed between the discharge auxiliary portion 7 and the tip portion 5b of the protruding electrode portion 5, and triggered by this initial discharge, Discharge progresses and discharge is performed between the pair of flange portions 4 or between the protruding electrode portions 5.

  Thus, in the surge protection element 1 of the present embodiment, since the opposing surfaces 5a of the pair of protruding electrode portions 5 are parallel to each other and inclined with respect to the axis C of the insulating tube 2, the axis C and the opposing surface 5a. If the angle with respect to is θ, the displacement (error) of the dimension in the axial direction is reduced to a displacement of cos θ times, so that the displacement of the discharge start voltage Vs can be made smaller than before.

Further, since the tip portion 5b of the protruding electrode portion 5 is chamfered, it is possible to suppress the concentration of the electric field at the corner portion of the tip portion 5b.
Further, since the pair of discharge active layers 6 are formed in the same shape at positions overlapping each other when viewed in the vertical direction of the pair of opposed surfaces 5a, they are the same as each other from the pair of discharge active layers 6 toward the opposite direction. It becomes possible to perform electron emission.

  Furthermore, since the discharge auxiliary portion 7 is formed in a region other than the region facing and adjacent to the tip portions 5b of the pair of protruding electrode portions 5, the tip portion 5b of the protruding electrode portion 5 is formed on the inner peripheral surface of the insulating tube 2. By disposing the discharge assisting portion 7 so as to avoid the region facing the distal end portion 5b that is most susceptible to the discharge generated in the above, deterioration of the discharge assisting portion 7 can be suppressed.

  Next, a second embodiment of the surge protection element according to the present invention will be described below with reference to FIGS. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The difference between the second embodiment and the first embodiment is that the first embodiment is a rectangular tube-shaped insulating tube 2, whereas the surge protection element 21 of the second embodiment is shown in FIGS. As shown in FIG. 5, the insulating tube 22 has a round cylindrical shape.
That is, in the second embodiment, the axis of the projecting electrode portion 5 and the axis of the insulating tube 22 coincide with each other, and the distance between the inner peripheral surface of the insulating tube 22 and the outer peripheral surface of the projecting electrode portion 5 is the circumference. The direction is constant.

Also in the second embodiment, the opposing surfaces 5 a of the pair of protruding electrode portions 5 are parallel to each other and inclined with respect to the axis C of the insulating tube 2.
Thus, even in the surge protection element 21 of the second embodiment, as in the first embodiment, even if the gap width between the pair of protruding electrode portions 5 varies, the variation in the center value of the discharge start voltage Vs is suppressed. Highly accurate discharge characteristics can be obtained.

  The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1,21 ... Surge protective element 2,22 ... Insulating tube, 3 ... Sealing electrode, 4 ... Flange part, 5 ... Projection electrode part, 5a ... Opposite surface of projection electrode part, 5b ... Tip part of projection electrode part , 6 ... discharge active layer, 7 ... discharge auxiliary part, C ... axis of insulating tube

Claims (4)

An insulating tube;
A pair of sealing electrodes for closing the opening at both ends of the insulating tube and sealing the discharge control gas inside;
A pair of sealing electrodes, a pair of flange portions fixed in close contact with both end openings of the insulating tube;
A pair of protruding electrode portions protruding inward from the pair of flange portions and facing each other;
The surge protection element, wherein opposing surfaces of the pair of protruding electrode portions are planes parallel to each other and inclined in the same direction with respect to the axis of the insulating tube. The surge protection element according to claim 1,
A surge protection element, wherein a tip portion of the protruding electrode portion is chamfered. The surge protection element according to claim 1 or 2,
A pair of discharge active layers are formed of materials having higher electron emission characteristics than the material of the sealing electrode on the opposing surfaces of the pair of protruding electrode portions,
The surge protection element, wherein the pair of discharge active layers are formed in the same shape at positions overlapping each other when viewed in the vertical direction of the pair of opposed surfaces. In the surge protection element according to any one of claims 1 to 3,
A discharge auxiliary portion formed of an ion source material on the inner peripheral surface of the insulating tube;
The surge protection element, wherein the discharge assisting portion is formed in a region other than a region facing and adjacent to the tip portions of the pair of protruding electrode portions.

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