JPH0113361Y2 - - 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 body 1 is made of silicon carbide (SiC), tin oxide (Sn02), or iron oxide (Fe203).
A sintered body of titanium oxide (Ti02) or titanium oxide (Ti02) is used.

FIG. 3 is an electrical equivalent circuit diagram of the conventional varistor shown in FIGS. 1 and 2, in which the varistor characteristic is
In parallel with Vz2, Vz3, Vz4, capacitance C25,
The circuit configuration is that C35 and C45 are 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 electrostatic capacitance C25, C35,
It may be necessary to make adjustments to the C45. There are methods to adjust this capacitance value, such as selecting the composition of the varistor body 1 and selecting the manufacturing method, but there is also a method by adjusting the electrode area, such as reducing the electrode area of the electrodes 2 and 3. Easiest and surest. However, when adjusting the electrode area,
If the area is reduced, the adhesion area of the electrodes 2 to 4 to the varistor body 1 is also reduced, which reduces the electrode adhesion strength and causes problems such as electrode peeling. Also, when the electrode area becomes smaller,
A sufficient soldering area for soldering lead wires and the like to the electrodes 2 to 4 cannot be secured, making soldering difficult.

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, allows easy soldering of lead wires to electrodes, and facilitates electrode formation work.

Configuration of the Present Invention In order to achieve the above object, the varistor according to the present invention is characterized by having a glass layer formed in an annular shape in a portion below the electrode.

Embodiment FIG. 4 is a front partial cross-sectional view of a varistor according to the present invention, FIG. 5 is a cross-sectional view taken along line A--A in FIG. 4, and FIG. 6 is a rear partial cross-sectional view thereof.
In the figures, the same reference numerals as in FIGS. 1 and 2 indicate the same components. In this embodiment, glass layers 6 and 7 are formed in substantially coaxial annular shapes approximately at the center of both sides of a varistor body 1 formed in an annular shape. While forming divided electrodes 2 to 4,
It has a structure in which an annular common electrode 5 is deposited on a glass layer 7 provided on the back side. The glass layers 6 and 7 can be easily formed by applying a glass paste by screen printing and baking.

As described above, when the glass layers 6 and 7 are formed under a portion of the electrodes 2 to 5, the electrode area of the electrodes 2 to 5 that contributes to acquisition of capacitance is reduced by the overlapping glass layers below the electrodes 2 to 5. It is reduced by the area of 6 and 7. Therefore, the capacitance is reduced accordingly. That is, by adjusting the width, formation position, etc. of the glass layers 6 and 7 that overlap under the electrodes 2 to 5,
The capacitance obtained in 5 can be easily adjusted.

On the other hand, since the electrodes 2 to 5 are also formed on the glass layers 6 and 7, the surface area of the electrodes 2 to 5 is the same as that of the conventional one, despite the presence of the glass layers 6 and 7. can be kept.

Therefore, without reducing the surface area of the electrodes 2 to 5, only the electrode area that contributes to acquiring capacitance is reduced by the glass layers 6 and 7, and the electrode adhesion strength is high and lead wires etc. It becomes possible to obtain a varistor that is easy to solder and whose capacitance can be easily adjusted. In addition, glass layers 6 and 7
has a linear expansion coefficient similar to that of the varistor element body 1 and the electrodes 2 to 5, and can be firmly bonded to both by means such as baking treatment, so peeling etc. will not occur. Creates a strong adhesive structure with no cracks.

Furthermore, since the glass layer 6 is formed in an annular shape, it has no directionality in relation to the plurality of divided electrodes 2 to 4. Therefore, after forming the glass layer 6, when forming the electrodes 2 to 4 thereon, there is no need to worry about directionality, and the printing operation of the electrodes 2 to 4 becomes very easy. Moreover, since it is annular, the width of the glass layers 6 and 7 is
By selecting the formation position, etc., the area can be finely adjusted over a wide range. Therefore, effects such as being able to finely adjust the capacitance between the electrodes over a wide range can also be obtained.

Note that the type or shape of the varistor body 1, the number, shape, or structure of the electrodes 2 to 5, or the formation positions and widths of the glass layers 6 and 7 may be arbitrary and not limited to the examples. Further, in this embodiment, the glass layers 6 and 7 are provided on both sides of the varistor body 1, but for example, the glass layer 7 is omitted and the glass layer 6 is
It is also possible to have a structure that only includes the following. Furthermore, the glass layers 6 and 7 are, as shown in FIGS. 7 and 8,
They may be formed at positions that do not face each other.

Effects of the present invention As stated above, the barista according to the present invention has
Since it is characterized by having a glass layer formed in an annular shape in a part under the electrode, it is possible to reduce the capacitance without reducing the effective surface area of the electrode, and it is possible to adjust the capacitance. It is possible to provide a varistor that is easy to use, has high electrode adhesion strength, is easy to solder lead wires to the electrodes, and is easy to form electrodes.

[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 4 is a sectional view taken along the line A--A in FIG. 4, FIG. 6 is a rear partial sectional view, FIG. 7 is a front partial sectional view of another embodiment, and FIG. 8 is a rear partial sectional view. 1... Varistor element body, 2-5... Electrode, 6,7
...Glass layer, G...gap.

Claims (1)

[Claims for Utility Model Registration] (1) A varistor characterized by having a glass layer formed in an annular shape in a portion below an electrode. (2) The electrode having the glass layer underneath is composed of a plurality of electrodes divided by gaps and arranged on the same circumference, and the glass layer is arranged concentrically with respect to the arrangement of the plurality of electrodes. A barista characterized by being formed into a shape. (3) The utility model according to claim 1, wherein the electrode having the glass layer thereunder is formed in an annular shape, and the glass layer is formed concentrically with respect to the electrode. Barista.