JPH02264403A - High tension variable resistor - Google Patents

Abstract

PURPOSE:To improve revolution life characteristics and pulse-resisting characteristics by a method wherein an Ag electrode material is not used as a substrate at the position which becomes the starting and ending points of the sliding piece of a film resistor, a cermet resisting material same as the film resistor is used, and the generation of change in material of the film resistor on the above-mentioned part is prevented. CONSTITUTION:An insulated substrate 3 such as alumina and the like is fixed to the stepped part 2 on the inner wall of the lower case 1 of a high tension variable resistor, a pair of terminal electrodes 4 and 5 are formed on the upper surface of the above-mentioned substrate 3, and reference point electrodes 6 and 7 are formed linking to the electrodes 4 and 5. The electrodes 4 and 5 are formed by printing the resistive paste of an Ag electrode material, and reference electrodes 6 and 7 are formed by printing resistive paste, consisting of a cermet resistance material having the surface resistance lower than that of a film resistor 8. Then, notches 9 and 10 are formed at the position adjacent to the reference point electrodes 6 and 7 which become the starting and ending points of the sliding piece 13 of the film resistor 8, and the reference point electrodes 6 and 7 located between the substrate 3 and the film resistor 8 are exposed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a high-voltage variable resistor, and more particularly to a film resistor made of a cermet resistance material forming a variable resistance section provided on an insulating substrate surface. and a slider that slides on the film resistor.

(Prior Art) Conventionally, this type of high voltage variable resistor has been configured as shown in FIG. 4, for example.

That is, an insulating substrate 23 made of alumina or the like is adhesively fixed to an inner wall stepped portion 22 of a lower case 2I made of resin and having an opening on one side. As shown in FIG. 5, this insulating substrate 23 has a pair of terminal electrodes 24 and 25 formed on its upper surface.
A horse-shaped film resistor 26 is formed spanning the pair of terminal electrodes 24, 25 and forming a variable resistance section from above. In this film resistor 26, the part in contact with one terminal electrode 24 becomes the starting point of a slider to be described later, and the part in contact with the other terminal electrode 25 becomes the end point of the slider. Here, the terminal electrode 24 and 25 portions at the starting and ending points will be referred to as reference point electrodes. Then, the insulating substrate 2 surrounded by the film resistor 26
A center electrode 27 connected to the other terminal electrode 25 is formed in the center portion of the top of the electrode 3, and a film resistor 28 is formed to cover the center electrode 27 and the connecting portion between the center electrode 27 and the terminal electrode 25. It is formed.

An upper case 29 made of resin and having an opening on one side is fitted into the lower case 21, and a film resistor 29 is inserted into the upper case 29 with the film resistor 27 centered on the center electrode 27 on the surface of the insulating substrate 23.
A rotating shaft 31 to which a slider 30 is attached that slides on 6
is bearing.

(Problem to be Solved by the Invention) In the above high voltage variable resistor, the terminal electrode 24.2
5 is formed by printing a conductive paste made of an Ag-based electrode material such as Ag, Ag-Pt, Ag-Pd, etc., and the film resistor 26 is made of a cermet such as ruthenium oxide having a resistance on the order of IOMΩ/mm. It is formed by printing a resistive paste made of a resistive material. here,
The sheet resistance indicates the resistance value between opposing ends of a film resistor formed in a square shape.

However, high-voltage variable resistors using the above electrode materials and resistance materials have a problem in that their rotational life characteristics and pulse resistance characteristics are not very good. Furthermore, to be more specific, the initial resistance value between the starting point and the ending point is 100
When the slider 30 is slid 500 times between the starting point and the ending point on the film resistor 26 formed to have MΩ, the resistance value change (rotation life characteristic) is -5% (5 variable resistors average value). Also, the initial resistance value between the starting point and the ending point is 10
In the film resistor 26 formed to have a resistance of 0 MΩ,
The slider 30 is adjusted to a position where the resistance value between the pair of terminal electrodes 24 and 25 is approximately 5 MΩ, and in this state, a pulse voltage of 27 kV DC is applied for 10 minutes between the pair of terminal electrodes 24 and 25.
The change in resistance value when the voltage is applied twice (pulse resistance characteristics) is -
It was 80% (average value of 5 variable resistors). This pulse voltage is 200 o
This is obtained by connecting a pF capacitor between the terminal electrodes 24 and 25 and discharging its charge.

As described above, the reason why the rotational life characteristics and pulse resistance characteristics of conventional high voltage variable resistors are not so good is because the electrode material of the terminal electrodes 24 and 25 is Ag-based. This is thought to be due to the diffusion of the cermet into the cermet resistance material.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a high-voltage variable resistor with good rotational life characteristics and pulse resistance characteristics.

(Means for Solving the Problem) In order to achieve such an object, in the high voltage variable resistor of the present invention, a slider on a film resistor made of a cermet resistance material formed on an insulating substrate surface is used. A reference point electrode made of a cermet resistance material having a lower sheet resistance than the film resistor is provided between the film resistor and the insulating substrate at the starting and ending points of the film resistor.

(Function) The reference point electrodes at the starting and ending points of the slider of the film resistor are not made of conventional Ag-based electrode material, but are made of the same cermet resistance material as the film resistor, so the film at that part No material change occurs in the resistor, resulting in excellent rotational life characteristics and pulse resistance characteristics.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In FIG. 1, an insulating substrate 3 made of alumina or the like is fixed to an inner wall stepped portion 2 of a lower case 1 made of resin and having an opening on one side. As shown in FIG. 2, this insulating substrate 3 has a pair of terminal electrodes 4.5 formed on its upper surface, and a reference point electrode 6.7 connected to this terminal electrode 4.5. This terminal electrode 4.5 is formed by printing a conductive paste made of an Ag-based electrode material similar to the conventional one, and the reference point electrode 6.7 is formed by printing a conductive paste made of an Ag-based electrode material, for example, with a resistance of about 1 to 1 Ω/hole, which will be described later. It is formed by printing a resistance paste made of a cermet resistance material such as ruthenium oxide, which has a lower sheet resistance than a film resistor.

A reference point electrode 6 made of this cermet resistance material
．． A horse-shaped film resistor 8 is formed spanning over 7 and forming a variable resistance section. The film resistor 8 is formed by printing a resistance paste made of a cermet resistance material such as ruthenium oxide, which has a sheet resistance of about 10 MΩ/hole, similar to the conventional one.

Moreover, this film resistor 8 has notches 9. at positions where it contacts the reference point electrodes 6, 7, which are the starting and ending points of the slider. A reference point electrode 6° 7 located between the insulating substrate 3 and the film resistor 8 is exposed.

A center electrode 11 is formed at the center of the insulating substrate 3 surrounded by the film resistor 8 . This center electrode 11 is similar to the reference point electrode 6.7, for example 1
A resistive paste made of a cermet resistive material such as ruthenium oxide, which has a sheet resistance of about Ω/mm, lower than that of the film resistor 8, is printed and formed, and the same cermet resistive material as the center electrode 11 is used for the reference point electrode 7. It is connected.

An upper case 12 made of resin and having an opening on one side is fitted into the lower case l, and this upper case 12 has a center electrode 11 on the insulating substrate 3 surface (through which the film resistor 8 is slid). A rotating shaft 14 to which a moving slider 13 is attached is supported.

As is clear from the above description, the only difference between the high voltage variable resistor of the present invention and the conventional one is the structure of the film resistor etc. formed on the insulating substrate 3, and the other points are It is exactly the same as the conventional one. In the high-voltage variable resistor configured as described above, the change in resistance value representing the rotational life characteristics measured using the same method as before is -0.
, 1% or less, and the change in resistance value representing pulse resistance characteristics was -3% (all values are average values of five variable resistors).

In addition, in the high voltage variable resistor of the present invention, the cutouts 9. formed at the starting and ending points of the film resistor 8. IO is not necessarily essential.

Further, the center electrode 11 may be formed of the same Ag-based electrode material as in the past, and furthermore, another terminal electrode may be formed between the terminal electrodes 4.5 without being connected to the reference point electrode 7, It may be connected to that terminal electrode. In addition, the reference point electrode 6
．． The sheet resistance of the resistance material forming the resistor material 7 and the center electrode ll is not limited to the value as in the above embodiment, but may have a value lower than that of the film resistor 8 forming the variable resistance part. All you need is one. In addition, various other configurations can be adopted for the portions other than the insulating substrate 3.

Although the above embodiment concerns a high-voltage variable resistor with one variable resistance section, a similar configuration can be adopted for a high-voltage variable resistor with multiple variable resistance sections. .

That is, FIG. 3 shows an insulating substrate 15 of a high voltage variable resistor having two variable resistance sections.

Even in such a configuration, the reference point electrodes 18, 19, 20.21 and the center electrode 22.23 at the respective starting and ending points of the film resistor 16.17 forming the variable resistance section.
Conventionally, Ag-based electrode materials have been used, but at least for these reference point electrodes 1B and 19.20.21, a cermet resistance material with a lower sheet resistance than the cermet resistance material of the film resistor 16.17 is used. You can use

(Effects of the Invention) As is clear from the above explanation, according to the present invention,
A reference point electrode made of a cermet resistance material with a lower sheet resistance than the film resistor is provided between the film resistor and the insulating substrate at the starting and ending points of the slider on the film resistor, resulting in a long rotational life. It has excellent characteristics and pulse resistance.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a high-voltage variable resistor according to an embodiment of the present invention, Fig. 2 is a plan view of an insulating substrate used therein, and Fig. 3 is an insulation used in a high-voltage variable resistor of another embodiment. FIG. 3 is a plan view of the substrate. FIG. 4 is a sectional view of a conventional high voltage variable resistor, and FIG. 5 is a plan view of an insulating substrate used therein. I...Lower case, 2...Step part, 3...Insulating board,
4゜5...Terminal electrode, 6.7...Reference point electrode, 8.
... Film resistor, 9.10... Notch, 11... Center electrode, 12... Upper case, 13... Slider, 14...
... Rotating shaft, 15... Insulating substrate, 16.17... Film resistor, 18, 1920.21... Reference point electrode, 2
2.23...Center electrode.

Claims (1)

[Claims] (1) In a high-voltage variable resistor comprising a film resistor made of a cermet resistance material that forms a variable resistance section provided on an insulating substrate surface, and a slider that slides on the film resistor. , A reference point electrode made of a cermet resistance material having a lower sheet resistance than the film resistor is provided between the film resistor and the insulating substrate at the starting and ending points of the slider on the film resistor. Characteristic high voltage variable resistor.