JPS582011Y2 - high voltage variable resistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high voltage variable resistor, such as a focus variable resistor for a television receiver.

As shown in FIGS. 1 and 2, this type of resistor is made by printing a resistor 2 on a substrate 1 and firing it, which is housed in an insulating case 5 having a slider 3 and a rotating shaft 4 for adjustment thereof, and is also made of resin. external connection terminals 7 and 8 connected to both ends of the resistor 2 and an external connection terminal 9 connected to the slider 3;
The rotating shaft 4 is biased outwardly by the spring of the slider.
It also has a structure that protrudes to the outside.

However, the part where the slider 3 and the resistor 2 come into contact is hollow as shown in Figure 3, so moisture, corrosive gas, conductive ionic gas, dust, etc. can enter from the outside. Must not be.

If it were to flow in, corona discharge would occur in the resistor 2 portion, or internal leakage current would increase, resulting in heat generation in the resistor and burnout of the resistor.

For this reason, a rubber backing or a rubber ring is applied to prevent external harmful gases from flowing in through the gap in the rotating shaft 4 portion.

Figure 3 shows a conventional method of sealing by pressing a ring-shaped rubber 10 placed in the gap between the case 5 and the rotating shaft 4 with the spring force of the slider 3.
The disadvantage is that the hardness of the rubber changes or distorts during long-term use due to external forces, causing the sealing effect to be lost.Also, rubber is easily affected by external gases, such as ozone or fluid gas. It has the disadvantage of being significantly degraded.

Figure 4 shows a method that does not use sealing rubber, case 5.
In this conventional example, the fitting part between the rotary shaft 4 and the rotary shaft 4 is made as long as possible, and grease is used between the two to prevent the intrusion of external moisture and harmful gases. Since the length is longer than necessary, the gap between the molded product and the case becomes large, making it substantially difficult to prevent external objects from entering.

That is, although the case 5 is a molded product, the gap becomes larger in the direction of the base of the fitting portion due to the taper of the mold.

Furthermore, although FIG. 5 shows a method of preventing the intrusion from the outside by making the surface as short as possible and creating a grease retainer 11, it was still impossible to achieve a complete seal.

The present invention proposes a high-voltage variable resistor that has good processing accuracy, has a sufficient sealing effect, and is designed to maintain its effect stably over a long period of time.The details will be explained below according to the embodiment shown in the drawings. do.

As shown in FIGS. 6 to 8, in the present invention, a tapered portion 12 is provided on the rotating shaft 4 that drives the slider 3, and the case 5 is provided with a tapered portion 12.
A part of the inner surface of the tapered part 13 is shaped like a step, and the stepped part 13 and the tapered part 12 are in line contact with each other, and the space created between them is filled with grease 14.

Note that the grease 14 is, for example, compound grease.

Note that by pressing the rotating shaft 4 with the spring force of the slider 3, the contact pressure can be increased considerably.

Also, in Figure 7, external pressure P.

is applied, the pressure is reduced to Pl in the first stage,
In the second stage, the pressure is further reduced to P2, and so on, and so on, and so on. By performing P4, it can finally be made zero or close to zero.

In addition, when considering specifically the rolling properties of each step, in Fig. 8, the contact pressure Pa on the contact line of the first step is P8, the pressure due to the spring of the slider 3 is P8, and the external temperature is increased. When the internal pressure of the variable resistance part is p+ (however, Pl is at room temperature (2
If the inner diameter of the first stage is a, then the inner diameter of the second stage is b, then the contact pressure becomes zero at 5°C). However, as mentioned earlier, the external pressure also decreases as it goes to the later stages, so the sealing effect is not impaired.

According to the present invention, since a plurality of line contacts are made when fitting the case and the rotating shaft, a sealing effect can be easily and reliably obtained by setting the contact pressure higher than the external pressure in advance. It is extremely effective.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a conventional high voltage variable resistor, FIG. 2 is a perspective view of the completed state, and FIG. 3 is a side sectional view thereof. 4 and 5 are side sectional views of other conventional examples, respectively. FIG. 6 is a side sectional view of a high-voltage variable resistor embodying the present invention, FIG. 7 is an enlarged view of its main parts, and FIG. 8 is an explanatory diagram thereof. 1...Substrate, 2...Resistor, 3...
...Slider, 4...Rotating shaft, 5...
Case, 6... Resin, 7, 8.9...
External connection terminal, 12...Tapered portion, 13...
...Stepped portion, 14...Grease.

Claims (1)

[Scope of utility model registration request] A substrate having a resistor having at least a circular shape and a slider provided opposite to the substrate and sliding on the circular portion of the substrate are arranged in one case, and the resistor has a circular shape. A high voltage variable resistor having an external connection terminal connected to both ends and a slider, and a part of the rotating shaft connected to the slider and urged outwardly exposed to the outside, the rotating shaft being connected to the rotating shaft. A tapered part is provided, and a part of the inner surface of the case is shaped like a step, and the stepped part and the tapered part are brought into line contact, and the space created between them is filled with grease. High voltage variable resistor.