Rotary variable resistor

Details Rotary variable resistor Rotary variable resistor

1999-11-01

2001-08-14

Easthom, Karl D. (Department: 2832)

Electrical resistors

Mechanically variable

Movable contact electrically adjustable over length of...

C338S163000, C338S174000, C338S188000

Reexamination Certificate

active

06275140

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary variable resistor suitable for use in various types of electronic apparatuses.
2. Description of the Related Art
A conventional rotary variable resistor will be described with reference to
FIGS. 7 and 8
.
A substrate
31
made of a molded article of synthetic resin has a circular base
31
a
, a rectangular leader
31
b
, and a hole formed in the center of the base
31
a.
Plural terminals
32
and
33
are made of metallic materials and are buried in the leader
31
b
of the substrate
31
. Ends
32
a
and
33
a
of the terminals
32
and
33
project outward from a side of the leader
31
b
, and the other ends
32
b
and
33
b
are exposed at the surface of the substrate
31
.
A first collector
34
made of a conductive material, such as silver, is formed on the surface of the substrate
31
, and has an annular part
34
a
provided around the hole
31
c
, and a leader
34
b
leading from the annular part
34
a
to the leader
31
b
. The leader
34
b
is connected to the other end of one of the terminals
32
.
A second collector
35
made of a conductive material, such as silver, is formed on the surface of the substrate
31
, and has a circular-arc part
35
a
provided on the outer periphery of the annular part
34
a
and a leader
35
b
leading from the circular-arc part
35
a
to the leader
31
b
. The leader
35
b
is connected to the other end
32
b
of the other one of the terminals
32
.
A first resistor
36
is formed on the surface of the substrate
31
, and has a horseshoe-shaped resistance part
36
a
formed at the outer periphery of the circular-arc part
35
a
and a leader
36
b
linearly leading from both ends of the resistance part
36
a
to the leader
31
b
. The leader
36
b
is connected to the other end
33
b
of one of the terminals
33
.
A second resistor
37
is formed on the surface of the substrate
31
and has a horseshoe-shaped resistance part
37
a
formed on the outer periphery of the resistance part
36
a
of the first resistor
36
and a leader
37
b
linearly leading from both ends of the resistance part
37
a
to the leader
31
b
. The leader
37
b
is connected to the other end
33
b
of one of the terminals
33
.
The first and second resistance parts
36
a
and
37
a
are connected to each other at one end thereof.
A knob
38
made of an insulating material is shaped like a disk, and a hole
38
is formed in the center thereof. Two sliding elements
39
and
40
are fixed to the underside of the knob
38
.
The sliding element
39
slides on the first collector
34
and the resistance part
36
a
of the first resistor
36
, and the sliding element
40
slides on the second collector
35
and the resistance part
37
a
of the second resistor
37
.
A shaft
37
is inserted through the hole
38
a
of the knob
38
and the hole
31
c
of the substrate
31
to thereby rotatably mount the knob
38
on the substrate
31
.
When the knob
38
is rotated, the slider elements
39
and
40
are rotated, the slider element
39
slides on the first collector
34
and the first resistor
36
to vary the value of resistance between the terminals
32
and
33
, and the slider element
40
slides on the second collector
35
and the second resistor
37
to vary the value of resistance between the terminals
32
and
33
. This allows the two resistors
36
and
37
to be variable.
In the above-described conventional rotary variable resistor, since the first collector
34
has the leader
34
b
leading from the circular part
34
a
to the leader
31
b
of the substrate
31
, a space for providing the leader
34
b
is required and the size of the resistor is thereby increased.
Therefore, the conventional rotary variable resistor is not suitable for size reduction.
In addition, the presence of the leader
34
b
interferes with the approach to both ends of the resistor
36
. and therefore an effective angle of the resistor
36
is smaller.
Furthermore, in the first resistor
36
, the leader
36
b
leading linearly from both ends of the resistance part
36
a
to the leader
31
b
is provided, and the leader
36
b
is connected to the other end
33
b
of one of the terminals
33
. Therefore, the space of the leader
36
b
is increased, and is not suitable for size reduction.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a rotary variable resistor capable of achieving a reduction in size by effectively using a surface of a substrate.
In accordance with an aspect of the present invention, there is provided a rotary variable resistor including: a substrate comprising synthetic resin; a first terminal comprising metal, embedded in said substrate, and leading from a side surface of the substrate; an annular collector formed on the surface of the substrate; a resistor formed on the surface of the substrate; and a sliding element sliding on the resistor and the collector, wherein an exposed part exposed at the surface of the substrate is formed on the first terminal within a range of the width of the annular collector, and the first terminal is connected to the collector at the exposed part.
In the rotary variable resistor, the sliding element may slide on the collector within a range not including the exposed part of the terminal.
In addition, in the rotary variable resistor, the resistor may be formed in a circular-arc shape on the outer periphery of the collector and both ends of the resistor may be disposed adjacent to each other, and a leader including silver and the like may be formed on the surface of the substrate so as to be curved along the outer shape of the resistor, and an end of the leader may be connected to an end of the resistor.
Furthermore, in the rotary variable resistor, exposed part of the first terminal may be formed at a position opposite to an end of the resistor across a hole formed in the substrate, and a second terminal may be embedded in the substrate, and the second terminal may have an exposed part exposed at the surface of the substrate, and the second terminal may be connected to the leader at the exposed part.


REFERENCES:
patent: 3579169 (1971-05-01), Dickinson
patent: 4210896 (1980-07-01), Benthuysen
patent: 4429297 (1984-01-01), Nakatsu
patent: 4839960 (1989-06-01), Yokoi et al.
patent: 4935718 (1990-06-01), Yagi et al.
patent: 4994782 (1991-02-01), Watanabe et al.
patent: 5059940 (1991-10-01), Thomas, Jr.
patent: 5847640 (1998-12-01), Fukaya et al.
patent: 02 101 708 (1990-07-01), None
patent: 02 101 705 (1990-07-01), None
patent: 7-245203 (1995-09-01), None
Japanese Unexamined Utility Model Publication No. 3-81607, 2 pages of English copy, 14 pages of publication and 8 pages of drawings in Japanese, dated Aug. 21, 1991.

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