JPH0311844Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Purpose of the Invention) Industrial Application Field The present invention relates to a variable resistor for an electronic tuner used for channel selection in a television receiver.

BACKGROUND ART A typical variable resistor for an electronic tuner has a variable resistor section 1, as shown in the plan view of FIG.
and a rotation drive section 2. The rotational drive shaft 2d of the rotational drive section 2 is the rotational shaft 1c of the variable resistance section 1.
By rotating the terminals 1a and 1b by a desired amount,
The resistance value between them is set to a desired value. Such an electronic tuner variable resistor is installed for each channel.

As shown in the sectional view of FIG. 5 (B-B' sectional view of FIG. 4), a typical rotary drive unit 2 includes a worm gear consisting of a wheel 2a and a worm 2b, and a worm gear that supports and accommodates the worm gear. It is composed of a box body 2c. When the end 2e of the worm exposed from the box 2c is rotated with a screwdriver while monitoring the electrical characteristics, the rotary drive shaft 2d rotates, and the resistance value of the variable resistor 1 selects the desired channel. is set to the value for

Problems to be solved by the invention In order to improve the accuracy of fine adjustment in the final stage, the above-mentioned conventional variable resistor for electronic tuners has the following features:
It uses a large speed ratio of several dozen. Therefore, when manufacturing and assembling a variable resistor for selecting channels at the high-frequency end and low-frequency end of the band, the worm shaft must be rotated dozens of times, and it takes time to set the resistance value. There is a problem. A similar problem occurs when a user switches between a high frequency channel and a low frequency channel according to his/her preference.

(Structure of the invention) Means for solving the problems The variable resistor for an electronic tuner of the present invention, which solves the problems of the prior art described above, has a box body, a spring body that presses the worm toward the wheel, and a wheel. The wheel is configured to include a support mechanism that supports the worm while allowing movement until the wheel is disengaged, and an opening that exposes a part of the outer circumference of the wheel.

Effects According to the present invention having the above configuration, first, with the wheel and worm disengaged, the worm is rotated using a part of the worm's circumference exposed through the opening of the box as a clue. Coarse corner adjustments are made. When this rough adjustment is completed, the worm is engaged with the wheel by the pressing force of the spring, and the final stage of fine adjustment is performed by rotating the shaft of the worm as in the conventional case.

Hereinafter, details of the structure and operation of the present invention will be explained using examples.

Embodiment FIG. 1 is a plan view showing the configuration of an embodiment of the present invention, and FIGS. 2 and 3 are sectional views taken along line A-A' in FIG. 1.

The variable resistor for an electronic tuner of this embodiment is composed of a variable resistance section 10 and a rotation drive section 20, as shown in the plan view of FIG. Variable resistance section 1
0 includes terminals 11 and 12 and a rotating shaft 13 for changing the resistance value between the terminals. This rotary shaft 13 is a rotary drive shaft 21 of the rotary drive section 20.
It is coaxially connected to b.

As shown in the cross-sectional view of FIG. 2, the rotation drive unit 20 is composed of a worm gear consisting of a wheel 21 and a worm 22, and a box 23 that supports and houses the worm gear.

The rotating shaft 21b of the wheel 21 is supported by bearings 23d and 23e provided on the wall of the box 23. The rotating shaft of the worm 22 is supported by a bearing 23b provided at the top of the box and a bearing 23c provided at the bottom of the box.

A leaf spring 23d is provided inside the box body 23. One end of the leaf spring 23d is fixed to the inner wall of the box, and the other end is brought into contact with the upper part of the worm 22. The leaf spring 23d presses the worm 22 toward the wheel 21, thereby enabling the worm 22 and the wheel 21 to engage with each other. The bearing 23b that supports the upper part of the worm 22 has enough play to allow the upper part of the worm 22 to rotate clockwise in the figure until the engagement with the wheel 21 is released against the pressing force of the leaf spring 23d. are doing.

The top 21 of the worm 21 is located on the top surface of the box 23.
An opening 23a is formed to the extent that a is slightly exposed.

The channel selection operation by setting the resistance value of the variable resistance section 20 will be explained with reference to FIG. First, the top part 22e of the worm exposed from the box body 23 is rotated clockwise by the amount of play in the bearing 23b.
The engagement between the worm 22 and the wheel 21 is released. In this state, the resistance value is roughly adjusted by rotating the wheel 21 using the tips of the teeth formed on the top 21a of the wheel exposed through the opening 23a at the top of the box as a clue.

When this rough adjustment is completed, the top 22 of the worm
Release the restraint of e. As a result, the leaf spring 23d
The worm 22 is pressed toward the wheel 21 by the pressing force, and the two are engaged, resulting in the state shown in FIG. 2. In this state, the final stage of fine adjustment is performed by rotating the top portion 22e of the worm using a screwdriver or the like, as in the conventional case.

Although a configuration has been illustrated in which one end of the worm is used as a fulcrum and the other end is rotated, the worm may be configured to temporarily disengage from the wheel by translating both ends of the worm.

Furthermore, as a configuration for applying a pressing force to the wheel to the worm, an example has been shown in which the worm is pressed against the wheel, but the worm may be drawn toward the wheel.

(Effects of the Invention) As explained in detail above, the variable resistor for an electronic tuner of the present invention temporarily releases the engagement between the wheel and the worm, and exposes part of the wheel from the box body. Since it is constructed so that it can be directly rotated, it is possible to perform rough adjustment prior to the final stage of fine adjustment, which has the effect of significantly shortening the channel selection time during manufacturing and assembly.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of this configuration, FIG.
3 is a sectional view taken along line AA' of the rotary drive section 20 in FIG. 1, FIG. 4 is a plan view of the conventional device, and FIG. be. 10... Variable resistance section, 20... Rotation drive section, 1
3. Rotating shaft of variable resistance section, 21. Wheel,
22... Worm, 30... Box body, 21a... Exposed part of wheel, 21b... Wheel rotation axis,
23a...Opening that exposes a part of the wheel, 2
3b: Bearing with play, 23d: Spring body.

Claims (1)

[Claims for Utility Model Registration] A worm gear consisting of a variable resistance part having a rotating shaft for changing the resistance value, a wheel having the rotating shaft connected to the rotating shaft of the variable resistance part, and a worm meshing with the wheel. , a variable resistor for an electronic tuner comprising a box supporting and housing the worm gear, wherein the box is disengaged from the wheel and a spring body that applies a pressing force to the worm against the wheel. A variable resistor for an electronic tuner, comprising: a support mechanism that supports the worm while allowing the worm to move; and an opening that exposes a part of the outer periphery of the wheel.