JPH0341442Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Industrial Application Field) The present invention relates to a cylindrical varistor that can obtain a plurality of different varistor voltages. (Prior art) Conventionally, as a cylindrical varistor,
As shown in the figure, a cylindrical ceramic a whose main components are strontium titanate, titanium oxide, zinc oxide, etc. and has varistor properties has the entire inner circumferential surface, one end surface, and the edge of the outer circumferential surface connected to the end surface. It is known that a first electrode b made of silver, zinc, etc. is formed covering the first electrode b, and a second electrode c is formed on the remaining outer circumferential surface with a gap between the first electrode b and the second electrode c. The varistor voltage of such a varistor is 5V,
For IC operation such as 9V and 12V, for automotive use such as 12V and 24V,
Various voltages such as 100V and 200V for commercial power supply are set according to each application, and this varistor voltage is obtained by changing the wall thickness of the cylindrical ceramic. (Problem to be solved by the invention) According to the above-mentioned varistor, cylindrical ceramic varistors with various wall thicknesses corresponding to the varistor voltage are always available, and a specific wall thickness can be adjusted based on the specified varistor voltage. Since the ceramic varistor was selected, there were problems with poor production efficiency and high costs. An object of the present invention is to provide a cylindrical varistor that can solve these conventional problems. (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention includes at least one strip-shaped external electrode perpendicular to the axis of the ceramic on the outer peripheral surface of the cylindrical ceramic. At least two band-shaped internal electrodes perpendicular to the axis of the ceramic are provided on the circumferential surface, and internal electrodes at both outer ends are formed continuously from the inner circumferential surface of the ceramic to the outer circumferential edge via the end surface. By appropriately selecting the electrodes and external electrodes, one varistor element or a plurality of varistor elements connected in series can be formed by each internal electrode and each external electrode facing each other via the ceramic. It is characterized by (Example) An example of the present invention will be described with reference to the accompanying drawings. Example 1 In Figs. 1 and 2, 1 is a material whose main component is strontium titanate (SiTiO ₃ ), which has varistor characteristics, an outer diameter of 3.0 mmφ, an inner diameter of 2.3 mmφ, and a length of
It is a fired cylindrical ceramic with a thickness of 10.0 mm and a wall thickness of 0.35 mm, and a part of the inner circumferential surface, one end surface, and the edge of the outer circumferential surface of the cylindrical ceramic 1 are continuously coated with zinc (Zn) as the main component. Further, the same electrode paste is continuously applied to the remaining inner circumferential surface, the other end surface, and the other edge of the outer circumferential surface of the cylindrical ceramic 1 through gaps with the electrode paste. Further, electrode paste is applied in a ring shape at two places on the outer peripheral surface of the cylindrical ceramic 1 through a gap with the above electrode paste, perpendicular to the axis of the cylindrical ceramic 1, and the electrode paste is baked at 650°C. A copper film is formed on the zinc film formed by electroless plating to form two internal electrodes 2 ₁ , 2 ₂ and two external electrodes 3 .
_1,32 were formed _. Here, the width of the outer peripheral surface of the internal electrode 2 ₁ is 1.0 mm, the width of the inner peripheral surface connected to this is 6.0 mm, and the width of the outer peripheral surface of the internal electrode 2 ₂ is 1.0 mm.
mm, the width of the inner peripheral surface connected to this is 3.5 mm, the widths of the outer electrodes 3 ₁ and 3 ₂ are 2.0 mm and 4.5 mm, respectively, the gap between these electrodes is 0.5 mm, and the inner electrode 2 ₁ is the outer electrode. Ceramic 1 is applied to 3 ₁ and a part of the external electrode 3 ₂ .
The inner electrode 2 ₂ faced a part of the outer electrode 3 ₂ with the ceramic 1 interposed therebetween. Thus, one varistor element is obtained between the internal electrode 2 ₁ and the external electrode 3 ₁ , and two varistor elements connected in series between the external electrode 3 ₁ and the external electrode 3 ₂ via the internal electrode 2 ₁ are obtained. Thus, three varistor elements connected in series between the external electrode 3 ₁ and the internal electrode 2 ₂ via the internal electrode 2 ₁ and the external electrode 3 ₂ are obtained. The varistor voltage V _1n and the voltage nonlinearity index α of this varistor were determined by the measuring circuit shown in FIG. In this circuit, the internal electrode 2 ₁ and the external electrode 3 ₁ of the varistor, or the external electrode 3 ₁ are connected to the measurement terminals X and Y.
and 3 ₂ , or connect the external electrode 3 ₁ and the internal electrode 2 ₂ respectively, close the switch S and adjust the voltage of the DC power supply E, and calculate the voltage between the terminals V _1n when the current flowing through the DC ammeter A is 1 mA. and the voltage between the terminals at 10mA
V _10n was read with a digital voltmeter V, and the values of V _1n and V _10n were substituted into the following equation to obtain the voltage nonlinearity index α. α=1/10g (V10m/V1m) The varistor voltage and voltage non-linearity index thus determined are shown in the table below.

[Table] Example 2 In this example, as shown in the third diagram, an annular third internal electrode 2 is provided in addition to the two internal electrodes 2 ₁ and 2 ₃ formed in the same manner as in Example 1 as internal electrodes. ₂ was formed on the inner peripheral surface of the cylindrical ceramic 1. The length of the cylindrical ceramic 1 is 8.5 mm, and the internal electrodes 2 ₁ and 2 ₃
The width of the inner circumferential surface of is 3.0 mm, and the width of internal electrode ₂ is 3.0 mm.
mm, the outer electrodes 3 ₁ and 3 ₂ are each 2.5 mm, and the outer electrode 3 ₁ faces the inner electrodes 2 1 and 2 _{2 .}
was formed by the same method and under the same conditions as in Example 1, except that the external electrodes 3 ₂ were disposed opposite the internal electrodes 2 ₂ and 2 ₃ , respectively. In this way, one varistor element is obtained between the external electrode 3 ₁ and the internal electrode 2 ₁ , and the external electrode 3 ₁ and the external electrode 3 ₂
Two series connected varistor elements are obtained between the outer electrode 3 ₁ and the inner electrode 2 3 , three series connected varistor elements are obtained between the outer electrode 3 ₁ and the inner electrode 2 3 , and between the inner electrode 2 ₁ and the inner electrode 2 ₃ Four series connected varistor elements are obtained. The varistor voltage and voltage nonlinear coefficient α of this varistor are shown in the table below.

[Table] Example 3 In this example, as shown in the fourth diagram, two electrodes 2 are used as internal electrodes, which are continuous to the inner circumferential surface, end surface, and outer circumferential edge of the cylindrical ceramic 1, as in Example 1. ₁ and 2 ₂ were formed, and an external electrode 3 ₁ was formed on the outer peripheral surface so as to face the two internal electrodes 2 ₁ and 2 ₂ . In this way, one varistor element is obtained between the internal electrode 2 ₁ and the external electrode 3 ₁ , and two varistor elements connected in series are obtained between the internal electrode 2 ₁ and the internal electrode. (Effects of the invention) As explained above, according to the invention, 1
A varistor having a plurality of varistor voltages can be obtained from a varistor having one cylindrical ceramic, which has the effect of improving production efficiency and reducing costs.

[Brief explanation of the drawing]

1 and 2 are a sectional view and a perspective view of one embodiment of the present invention, FIGS. 3 and 4 are sectional views of other embodiments of the present invention, respectively, and FIG. 5 is a measurement circuit diagram. 6 and 7 are a sectional view and a perspective view of a conventional cylindrical varistor. DESCRIPTION OF SYMBOLS 1...Cylindrical ceramic, ₂₁ , ₂₂ , ₂₃ ...Internal electrode, ₃₁ , ₃₂ ...External electrode.

Claims (1)

[Scope of utility model registration request] At least one belt-shaped external electrode perpendicular to the axis of the ceramic is provided on the outer peripheral surface of the cylindrical ceramic, and at least two belt-shaped internal electrodes are provided perpendicular to the axis of the ceramic on the inner peripheral surface of the ceramic, Internal electrodes at both outer ends are formed continuously from the inner circumferential surface of the ceramic through the end surface to the outer circumferential edge, and by appropriately selecting the internal electrodes and the external electrodes, it is possible to form internal electrodes facing each other through the ceramic. A cylindrical varistor characterized in that one varistor element or a plurality of varistor elements connected in series are formed with each external electrode.