JPH0214162Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a varistor used for noise prevention of small DC motors related to audio equipment, protection of relay contacts, protection of semiconductor elements against static electricity, and the like.

Conventional varistors of this type generally have a structure in which one or more electrodes are adhered to the front or back surface or both surfaces of a varistor element body formed in an appropriate shape such as an annular shape. ing. 1 and 2 show an example of a conventional varistor,
A plurality of electrodes 2, 3, and 4 divided by a gap G are provided on the front surface of a varistor body 1 formed in an annular shape, and a common electrode 5 is provided on the back surface of the varistor body 1, which commonly faces the electrodes 2 to 4. It has a unique structure. The varistor element 1 is made of silicon carbide (SiC), tin oxide (SnO2), or iron oxide (Fe2O3).
A sintered body of titanium oxide (TiO2) or titanium oxide (TiO2) is used.

FIG. 3 is an electrical equivalent circuit diagram of the conventional varistor shown in FIGS. 1 and 2, in which the varistor characteristics are
In parallel with Vz2, Vz3, Vz4, capacitance C25, C35,
The circuit configuration is that C45 is connected.

Disadvantages of conventional technology Varistors cut off the voltage due to their varistor characteristics when spike-like spark noise, lead propagation noise, etc. exceed the varistor voltage, but in the voltage range where the applied voltage is lower than the varistor voltage, a type of Since it operates as a capacitor, the capacitance C25, C35, C45 that occurs between the electrodes due to the oscillation conditions of the motor circuit, etc.
It may be necessary to make adjustments. There are methods to adjust this capacitance value, such as selecting the composition of the varistor body 1 and selecting the manufacturing method. Easiest and surest. However, when adjusting the electrode area, if the area is made smaller, the electrode 2 with respect to the varistor body 1 becomes smaller.
Since the adhesion area of 4 to 4 also becomes smaller at the same time, the electrode adhesion strength decreases, causing problems such as electrode peeling. Also, when the electrode area becomes smaller, the electrode 2
It becomes impossible to secure a sufficient soldering area for soldering lead wires, etc. to 4, making it difficult to solder.

Purpose of the present invention Therefore, the present invention solves the conventional problems mentioned above, makes it possible to reduce the capacitance without reducing the effective surface area of the electrode, makes it easy to adjust the capacitance, and makes it possible to bond the electrode. It is an object of the present invention to provide a varistor that has high strength and that allows easy soldering of lead wires and the like to electrodes.

Structure of the present invention In order to achieve the above object, a varistor according to the present invention is a varistor having a glass layer in a part under the electrode, and the electrode is composed of a plurality of electrodes divided by a gap. The glass layer is provided under the gap and the edge of the electrode adjacent to the gap.

Embodiment FIG. 4 is a partial front sectional view of a varistor according to the present invention, and FIG. 5 is a side view thereof. In the figures, the same reference numerals as in FIGS. 1 and 2 indicate the same components. Reference numeral 6 denotes a glass layer formed under a portion of the electrodes 2 to 4. In this embodiment, the glass layer 6 is adhered to a portion of the gap G on one surface of the varistor body 1 formed in an annular shape, with its edge entering the area where the electrodes 2 to 4 are formed. It has been formed. The glass layer 6 is placed at the position where the gap G of the varistor body 1 is to be formed.
It can be easily formed with a width W2 larger than the width W1 of the gap G by applying glass paste or the like in advance and baking it.

As described above, when the glass layer 6 is formed under a portion of the electrodes 2 to 4, the electrode area of the electrodes 2 to 4, which contributes to acquiring capacitance, is reduced by the area of the glass layer 6 that overlaps below the electrodes 2 to 4. It is reduced by the area. Therefore, the capacitance is reduced accordingly. That is, by adjusting the area of the glass layer 6 that overlaps under the electrodes 2 to 4, the capacitance obtained by the electrodes 2 to 4 can be easily adjusted. In fact, the conventional capacitance is 100%
According to the present invention, this can be reduced to approximately 30%.

On the other hand, since the electrodes 2 to 4 are also formed on the glass layer 6, the surface area of the electrodes 2 to 4 can be kept at the same level as the conventional one, regardless of the presence of the glass layer 6. .

Therefore, without reducing the surface area of the electrodes 2 to 4, only the electrode area that contributes to acquiring capacitance is reduced by the glass layer 6, and the electrode adhesion strength is high, making it easy to solder lead wires, etc. to the electrodes. It becomes possible to obtain a varistor whose capacitance can be easily adjusted. Moreover, the glass layer 6 has a coefficient of linear expansion that is close to that of the varistor body 1 and the electrodes 2 to 4, and can be firmly bonded to both by means such as baking. This creates a strong adhesive structure that does not cause peeling.

Furthermore, since the glass layer 6 is provided under the gap G and the edges of the electrodes 2 to 4 adjacent to the gap G, the glass bonding area can be increased and the bonding strength can be increased.

Note that the type or shape of the varistor body 1 or the number, shape, or structure of the electrodes 2 to 4 may be arbitrary and not limited to the examples.

Effects of the present invention As stated above, the barista according to the present invention has
A varistor having a glass layer under a part of the electrode, the electrode being composed of a plurality of electrodes divided by a gap, the glass layer being under the gap and the edge of the electrode adjacent to the gap. Because the glass layer reduces only the electrode area that contributes to acquiring capacitance without reducing the effective surface area of the electrode, the electrode bonding strength is high and the lead wire to the electrode can be reduced. It is possible to provide a varistor that is easy to solder and whose capacitance can be easily adjusted.

[Brief explanation of the drawing]

FIG. 1 is a front view of a conventional varistor, FIG. 2 is a side view thereof, FIG. 3 is an electrical equivalent circuit diagram thereof, FIG. 4 is a front partial sectional view of the varistor according to the present invention, and FIG. 5 is also a side view thereof. 1... Varistor element body, 2-4... Electrode, 6...
Glass layer, G...gap.

Claims (1)

[Claims for Utility Model Registration] A varistor having a glass layer in a part under the electrode, the electrode being composed of a plurality of electrodes divided by a gap, and the glass layer being connected to the gap. A varistor characterized in that the varistor is provided under an edge of the electrode adjacent to the gap.