Variable resistance device

Details Variable resistance device Variable resistance device

2001-06-19

2002-09-03

Easthom, Karl D. (Department: 2832)

Electrical resistors

Mechanically variable

Movable contact electrically adjustable over length of...

C338S174000, C338S170000, C338S162000

Reexamination Certificate

active

06445279

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a variable resistance device; in particular, the invention relates to a variable resistance device that makes the assembling easier and enhances its quality.
2. Description of the Related Art
Variable resistance devices find many uses in electrical equipment. One common use of variable resistance devices is used to control voltage in, for example, flyback transformers.
When used in a flyback transformer, a variable resistance device must meet a number of requirements. The foremost requirement is size. This poses a problem for variable resistance devices that typically rely on electromechanical structures to provide variable resistance.
Known variable resistance devices also are typically constructed of a relatively large number of small parts, increasing the difficulty of assembly and, correspondingly, the cost of the devices. In addition, the reliability is impaired because of the likelihood that each of the many parts presents an opportunity for failure in the device.
One example of a known variable resistance device is shown in FIG.
1
. Such variable resistance device
10
is consisted of a substrate
11
and a rotor
12
. A resistive region
111
is formed on the substrate
11
. The resistive region
111
is consisted of a central part
1111
and a semi-circular path
1112
. A distance X
1
is maintained as a safe gap between the central part
1111
and the semi-circular path
1112
. The central part
1111
is electrically connected to an external circuit (not shown). A spring
121
is disposed at the bottom of the rotor
12
. The spring
121
has a first end
1211
and a second end
1212
.
The first end
1211
of the spring
121
is in contact with the central part
1111
of the resistive region
111
. The second end
1212
of the spring
121
is in contact with the semi-circular path
1112
of the resistive region
111
. The second end
1212
is movable along the semi-circular path
1112
.
Therefore, users can move the second end
1212
along the semi-circular path
1112
by rotating the rotor
12
to change the resistance.
The disadvantage of the variable resistance device
10
is that its size has a minimum limit. Specifically, since two ends of the spring
121
are on the same plane, in view of the safe gap X
1
, the size of the substrate
11
has a minimum limit.
The other example of a known variable resistance device is shown in FIG.
2
. Such variable resistance device
20
is also consisted of a substrate
21
and a rotor
22
. A resistive region
211
is formed on the substrate
21
. The resistive region
211
comprises a semi-circular path. A point C
1
is used as a center of the semi-circular path. A distance Y
2
is maintained as a safe gap between the point C
1
and the semi-circular path. The rotor
22
is provided with a rod
221
and an elastic strip
222
at its bottom. The elastic strip
222
has a first end
2221
and a second end
2222
. The rod
221
abuts the point C
1
of the substrate
21
. The first end
2221
is movable along the resistive region
211
, and the second end
2222
is electrically connected to an external circuit (not shown). Therefore, users can move the first end
2221
along the semi-circular path by rotating the rotor
22
to change the resistance.
As shown in
FIG. 2
, the first end
2221
of the variable resistance device
20
extends outwardly from the bottom of the rotor
22
in an inclined angle. Hence, comparing with the safe gap X
1
as shown in
FIG. 1
, the safe gap Y
2
can be reduced. As a result, the size of the substrate
21
can be decreased.
However, the disadvantages of the variable resistance device
20
are that its elastic strip
222
is easily deformed, it is hard to assemble, and it cannot be assembled repeatedly.
SUMMARY OF THE INVENTION
In view of the disadvantages of the aforementioned conventional variable resistance device, the invention provides a variable resistance device that can make the assembly easier and enhances its quality.
Accordingly, the variable resistance device of the invention comprises a substrate and a rotor. A resistive region is formed on the substrate. The rotor is disposed on the substrate, after which it is rotatable. The rotor comprises a first contact member, a mount, a rotating member and a second contact member. The first contact member has a first end and a second end, wherein the first end abuts the resistive region in an elastic manner. The mount is used for receiving the first contact member. The rotating member engages the mount. The second contact member, disposed between the mount and the rotating member, abuts the second end of the first contact member in a movable manner.
Furthermore, the mount has a first through hole and a receiving portion; therefore, the rotating member passes through the first through hole to engage the mount, and the receiving portion is used for receiving the first contact member.
Furthermore, the receiving portion is a second through hole.
Furthermore, the first contact member comprises a rivet, a spring and a ball. The rivet abuts the resistive region. The spring, surrounding the rivet, is disposed inside the second through hole and abutting the rivet in one end. The ball abuts the second contact member and the other end of the spring.
Furthermore, the first contact member comprises a spring, a first ball and a second ball. The spring is disposed inside the second through hole. The first ball is disposed between the second contact member and one end of the spring. The second ball is disposed between the substrate and the other end of the spring.
Furthermore, the first contact member comprises a rivet and a spring. The rivet abuts the resistive region in one end. The spring, surrounding the rivet, is disposed inside the second through hole.
Furthermore, the second contact member has a hollow portion for the rotating member passing through.
Furthermore, the variable resistance device further comprises a housing. The housing has a first portion for combining with the substrate and a second portion for combining with the rotor.
Furthermore, a variable resistance device of the invention comprises a substrate and a rotor. A resistive region is formed on the substrate. The rotor is rotatablly disposed on the substrate and comprises a first contact member, a mount, a rotating member, a second contact member and a cushion member. The first contact member has a first end and a second end. The first end abuts the resistive region. The mount is used for receiving the first contact member. The rotating member engages the mount. The second contact member, disposed between the mount and the rotating member, abuts the second end of the first contact member in a movable manner. The cushion member, disposed between the second contact member and the rotating member, is used for cushioning the contact between the first contact member and the resistive region.
Furthermore, a variable resistance device of the invention comprises a substrate and a rotor. A resistive region is formed on the substrate. The rotor is disposed on the substrate, after which it can rotate, and comprises a first contact member, a mount, a rotating member and a conducting interface. The first contact member has a first end and a second end. The first end abuts the resistive region. The mount is used for receiving the first contact member. The rotating member engages the mount, and the rotating member abuts the mount. The conducting interface is formed on a surface, abuts the mount, of the rotating member. The conducting interface abuts the second end of the first contact member in a movable manner.


REFERENCES:
patent: 3119089 (1964-01-01), Murry
patent: 3533043 (1970-10-01), Spaude
patent: 3629780 (1971-12-01), Burcham et al.
patent: 4821014 (1989-04-01), Masuda et al.
patent: 5726625 (1998-03-01), Hasebe et al.

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