JPH03180001A - Variable resistor - Google Patents

Abstract

PURPOSE:To prevent backlash by setting the hardness of the outer periphery of an elastic O-ring to a value lower than that of the center, and suppressing its distortion to a small value. CONSTITUTION:An elastic O-ring 8 is interposed, similarly to prior art, between a resistor board 5 and a rotor 2. The hardness of the outer periphery 8a of the ring 8 is set to a value lower than that of the center 8b. Accordingly, deformation of the ring 8 due to a frictional force between the rotating rotor 2 and the ring 8 can be prevented. Thus, returning repulsion force of the rotor 3 due to the distortion becomes very small, and the rotor 2 can be held at a set position. Thus, a backlash can be prevented.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to the structure of a variable resistor used in electronic equipment, etc., and particularly relates to a backlash prevention mechanism for a rotary variable resistor. be.

(Prior Art) A conventionally used rotary variable resistor will be explained.

In the attached Figures 4 and 5, there is a hole 1a in the center of the bottom.
A protrusion 2a protruding from the hole gila and a protrusion 2a are placed in a cylindrical case 1 having an opening tb on the upper surface.
A rotor 2 is provided with a slider 4 housed in a groove 2c drilled in the axial direction on the bottom surface 2b opposite to the rotor 2, and a resistor and a current collector electrode body that slide in pressure contact with the upper surface of the slider 4. A resistor substrate 5 printed and fired on the front surface 5a and an output extraction terminal 7 protruding from the back surface 5b of the resistor substrate 5 are housed. Further, the gap formed between the case 1 and the resistor substrate 5 is filled with an adhesive 6 and cured. By curing the adhesive 6, the output extraction terminal 7 is fixed so as not to move, and the opening 1b of the case 1 is sealed. In other words, the adhesive 6 serves as a base. The base may be made of an insulator integrally formed with the resistor substrate 5 instead of the adhesive 6. The rotor 2 has a resistance value adjusted on the surface of its protrusion 2a, as shown in FIG. When the phase driver groove 2d is carved and the rotor 2 is housed in the case 1, the stepped portion 2e of the rotor 2 can freely rotate inside the case 1 while being in contact with the inner circumferential surface 1d of the cavity of the case 1. It is stored in.

In addition, 3 is an elastic O-ring which is compressed between the rotor 2 and the resistor board 5 and serves as a complete seal, preventing unnecessary substances such as dust and grease from entering the surface 5a of the resistor board 5. It is something to do.

(Problem to be Solved by the Invention) In the conventional variable resistor, when adjusting the variable resistor to a predetermined setting value, the adjustment driver etc. is inserted into the driver groove 2d.
Adjustment is performed by rotating the rotor 2 when the rotor 2 is rotated, but due to the repulsive force caused by the displacement of the elastic O-ring 3 as the rotor 2 rotates, immediately after the adjustment, there is a slight rotation in the opposite direction to the rotated direction. Since a return phenomenon occurs, there is a problem in that delicate operations are required to adjust to a desired set value and it takes time.

Hereinafter, the return phenomenon of one revolution will be referred to as so-called backlash.The present invention aims to provide a variable resistor L supply that solves this problem.

(Means for solving problems) Means for preventing the above-mentioned backlash will be disclosed below.

A rotor 2 equipped with a slider 4 that can freely slide on the surface 5a of the resistor substrate 5 is housed in the case 1, and
In a variable resistor equipped with an elastic O-ring 8 for maintaining the airtightness of the elastic O-ring 8, the hardness of the central part 8b of the elastic O-ring 8 is high, the hardness of the outer peripheral part 8a is low, and in some cases, the hardness of the center part 8b of the elastic O-ring 8 is made low, and the resistor substrate and rotor are This variable resistor is characterized in that the hardness of the upper surface of the elastic O-ring facing the inner surface of the elastic O-ring is the same and lower than that of the core.

(Function) According to the present invention, in FIGS. 1 to 3 illustrating the embodiment, when the rotor 2 of the rotary variable resistor is rotated to change the resistance value, The accompanying elastic deformation of the elastic O-ring 8 is greatly reduced because the inner part 8b of the elastic O-ring has high hardness.

Furthermore, since the outer part 8a of the elastic O-ring 8 is formed to have an appropriate degree of elasticity, the airtightness between the first rotor 2 and the resistor board 5 is not lost. Therefore, even when the rotor 2 is rotated, Since the elastic deformation of the elastic O-ring 8 is very small, the so-called backlash phenomenon can be prevented.

(Example) Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 illustrate one embodiment of the present invention.The variable resistor of this embodiment is the same as the conventional example except for the O-ring, so the same components are The same reference numerals are given, and the explanation thereof will be omitted.

The elastic O-ring 8 of the present invention is interposed between the resistor substrate 5 and the rotor 2, as in the conventional example. The hardness of the outer peripheral portion 8a of this O-ring 8 is lower than the hardness of the central portion 8b.

Therefore, as pointed out in the conventional problem, when adjusting the variable resistance value setting by rotating the rotor 2, the elastic O-ring 8 is damaged by the frictional force between the rotating rotor 2 and the elastic O-ring 8. No deformation occurs, and the reason for this is as follows: Since the hardness of the inner part 8b of the elastic O-ring is higher than that of the outer part 8a, the distortion of the elastic O-ring 8 is set to be very small. Therefore, the repulsive force that causes the rotor 2 to return due to distortion becomes extremely small, and the rotor 2 can be maintained at the set position. As a result, backlash can be prevented from occurring.

FIG. 3 illustrates another embodiment of the elastic O-ring 8. A portion 8d of the O-ring 8 on the resistor substrate 5 side and a portion 8e on the rotor 2 side are formed to have the same hardness and to be lower than the core portion 8c of the O-ring 8. With this configuration, backlash can be prevented from occurring based on the same principle as in the first embodiment described above.

(Effects of the Invention) As explained above, according to the present invention, since the hardness of the outer peripheral part of the elastic O-ring is set lower than the hardness of the central part, when adjusting the set value by rotating the rotor once, 1. By suppressing the distortion of the elastic O-ring, backlash can be prevented, and the setting stability of the variable resistor can be improved, and the time required to set the set value can be shortened.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a variable resistor according to the present invention. Figure 2 is a cross-sectional view of the O-ring. FIG. 3 is a sectional view of another embodiment of the O-ring. FIG. 4 is a sectional view of a conventional variable resistor. FIG. 5 is a plan view of the rotor. 1... Case 2... Rotor 3... Elastic O-ring 4... Slider 5... Resistor board
7... Terminal 8... Elastic O-ring 8a... Outer circumferential part 8b of elastic O-ring... Center part 8C of elastic O-ring... Core part 8d of elastic O-ring... Outer part 8e...outer part of elastic O-ring

Claims (2)

[Claims] 1. In a variable resistor, a rotor equipped with a slider that can freely slide on the surface of a resistor board is rotatably housed in a case, and an elastic O-ring is interposed between the rotor and the resistor board. A rotary variable resistor characterized by an O-ring having high hardness at the center and low hardness at the outer periphery. 2. 2. The rotary variable resistor according to claim 1, wherein the upper surface of the elastic O-ring facing the resistor substrate and the rotor is formed to have the same hardness and lower hardness than the core thereof.