Linear sliding variable resistor

Details Linear sliding variable resistor Linear sliding variable resistor

2000-11-07

2001-11-06

Easthom, Karl D. (Department: 2832)

Electrical resistors

Mechanically variable

Movable contact electrically adjustable over length of...

C338S033000, C338S202000

Reexamination Certificate

active

06313730

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a linear sliding variable resistor for use in a position detecting sensor for example.
2. Description of Related Art
The general structure of a linear sliding variable resistor known as a conventional example is shown in the side sectional view of FIG.
5
. The linear sliding variable resistor is comprised of a case
23
having a through hole
21
in one end face and an opening
22
in the opposite side surface, an operating shaft inserted extending outward from inside of the case
23
through the through hole
21
, an insulated board
25
provided with an unillustrated electrically conductive pattern of resistance on the surface, a sliding contact
26
sliding on the electrically conductive pattern, a sliding contact retainer
27
holding the sliding contact
26
and secured on the operating shaft, a cover
28
attached at the opening
22
of the case
23
, and a spring
29
mounted between the cover
28
and the sliding contact retainer
27
.
The linear sliding variable resistor of the above-described configuration is assembled by the following procedure. First, the insulated board
25
is inserted from the opening
22
side of the case
23
, then the operating shaft
24
is inserted into a through hole
30
provided in the sliding contact retainer
27
. Subsequently, the operating shaft
24
and the sliding contact retainer
27
are inserted into the case
23
from the opening
22
side of the case
23
, with its forward end being inserted into the through hole
21
. Next, the spring
29
is inserted into the operating shaft
24
until the spring
29
comes into contact with the sliding contact retainer
27
. Then, the cover
28
is attached to the case
23
with the rear end of the operating shaft
24
inserted into the through hole
31
.
The sliding contact retainer
27
was a few millimeter small square part. Assembling the above-described conventional example of linear sliding variable resistor required time and labor, centering much of attention in supporting the small part firmly and inserting the operating shaft
24
into the through hole
30
measuring 1 to 2 mm in diameter, which is nearly the same as the operating shaft
24
.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, it is an object of this invention to provide an easy-to-assemble linear sliding variable resistor in which a sliding retainer can be easily and firmly fixed on the operating shaft without increasing the component count.
To achieve the object stated above, the linear sliding variable resistor of this invention comprises a case having a through hole, an operating shaft inserted in the through hole and axially movably held, an insulated board arranged in the case and having an electrically conductive pattern on the surface, a sliding contact sliding on the pattern, and a sliding contact retainer for retaining the sliding contact and fixed on the operating shaft; the sliding contact retainer having a pair of snap legs and a retaining section having a U-sectioned recess; and the operating shaft being held by the recess in the retaining section and the snap leg.
According to the above-described configuration, the operation for fixing the sliding contact retainer to the operating shaft needs just pushing the operating shaft into the recess of the bearing, thereby enabling a much easier assembling operation than conventional ones.
Furthermore, the operating shaft in this invention has a small-diameter portion; and the recess of the retainer is partly provided with stepped portions. The stepped portions fit the small-diameter portion, so that the sliding contact retainer may follow the axial movement of the operating shaft, thereby enabling reliable restriction of the axial direction of the sliding contact retainer and the operating shaft.
In this invention, the recess stated above is open in the opposite side of the surface of the sliding contact retainer on which the sliding contact is retained. Therefore, the sliding pressure of the sliding contact acts in a direction in which the sliding contact retainer is pressed against the operating shaft, thereby insuring more reliable retaining. The sliding contact retainer, having a simple shape of bilateral similarity, is advantageous for fabrication.
Furthermore, it is desirable for this invention that the retaining section is provided on either side of the snap leg along the axial direction of the operating shaft, and the bottom surface of the recess of the retaining section is in contact with the peripheral surface of the operating shaft. Because of this configuration, the positional relation between the operating shaft and the sliding contact retainer is properly kept, firmly securing the sliding contact retainer on the operating shaft.


REFERENCES:
patent: 3364454 (1968-01-01), Froebe
patent: 4053865 (1977-10-01), Brown, Jr.
patent: 4213112 (1980-07-01), Alman et al.
patent: 4473814 (1984-09-01), Blessing
patent: 4479107 (1984-10-01), Bleeke
patent: 11-23210 (1999-01-01), None

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