Electrical resistors – Mechanically variable – Movable contact electrically adjustable over length of...
Reexamination Certificate
2000-09-19
2001-05-29
Easthom, Karl D. (Department: 2832)
Electrical resistors
Mechanically variable
Movable contact electrically adjustable over length of...
C338S128000, C338S130000, C338S131000, C338S150000, C338S137000
Reexamination Certificate
active
06239688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a variable resistor in which a movable member formed with a resistor is attached to a fixed member having a slider element fixed thereto in such a way that the movable member can be reciprocated, and further the slider element and the resister are brought into sliding contact with each other.
2. Description of the Prior Art
Referring now to
FIGS. 12
to
14
, this type of variable resistor of the prior art will be described. This variable resistor is comprised of a cylindrical-formed insulating housing
51
acting as a fixed member; an insulating rotary shaft
52
rotatably stored in the housing
51
and acting as a movable member having an engaging part
52
a
in at least one end thereof to be engaged with a screw driver or the like; a flexible insulating sheet
53
wound around the rotary shaft
52
within the housing
51
; a resistance circuit
54
formed at this flexible insulating sheet
53
; a slider element
55
attached to the housing
51
is in sliding contact with the resistance circuit
54
; and a connecting terminal
56
connected to the slider element
55
.
FIG. 13
is a development view for showing the flexible insulating sheet
53
and the resistance circuit
54
arranged in the flexible insulating sheet.
FIG. 14
is a sectional view taken along line
14
—
14
of
FIG. 13
, wherein the resistance circuit
54
is comprised of one resistor
54
a
and two electrodes
54
b
,
54
c
extending in parallel with a circumferential direction of the rotary shaft
52
, and they are connected to each other in series with the resistor
54
a
being an intermediate one of them. The slider element
55
is comprised of three slider elements
55
a
,
55
b
,
55
c
of which extremity ends are in sliding contact with the resistor
54
a
and the electrodes
54
b
,
54
c
, respectively, and the connecting terminal
56
is comprised of three connecting terminals
56
a
,
56
b
,
56
c
each of which is electrically connected to the slider elements
55
a
,
55
b
,
55
c
, respectively.
The variable resistor constructed as described above is constituted such that when the rotary shaft
52
is turned by a screw driver and the like under a state in which a predetermined voltage is applied between the slider elements
55
b
,
55
c
through the connector terminals
56
b
,
56
c
, the resistance circuit
54
wound around the rotary shaft
52
is rotationally moved in respect to the slider elements
55
a
,
55
b
,
55
c
and then the sliding contact positions of the slider elements
55
a
,
55
b
,
55
c
on the resistor
54
a
and the electrodes
54
b
,
54
c
are changed. With such an arrangement as above, a resistance value (a voltage value) between the slider elements
55
a
,
55
b
and a resistance value (a voltage value) between the slider elements
55
a
,
55
c
are changed, an electrical signal (a voltage signal) corresponding to a rotation of the rotary shaft
52
is taken out of the connecting terminal
56
a
through the slider element
55
a.
Then, in the case that the resistance circuit
54
is formed on the flexible insulating sheet
53
, it is necessary to provide two steps: an electrode forming step and a resistor forming step, wherein at first, at the electrode forming step, the electrodes
54
b
,
54
c
such as a silver foil or a copper foil and the like are adhered by vapor deposition or adhered with adhesive agent, then the resistor
54
a
such as a beryllium foil, nichrome foil and tungsten foil or the like is adhered by vapor deposition or adhered with adhesive agent to form the resistance circuit
54
.
However, in the case of the prior art variable resistor described above, the slider elements
55
a
,
55
b
,
55
c
fixed to the housing
51
slide on the resistor
54
a
and the electrodes
54
b
,
54
c
wound around the rotary shaft
52
under a rotation of the rotary shaft
52
. Due to this fact, the prior art needs not only a troublesome step for forming the electrodes
54
b
,
54
c
, but also requires the electrode forming step and the resistor forming step, resulting in that an entire manufacturing step for the variable resistor is extend in addition due to the fact that there is present only one resistor
54
a
and its maximum length merely corresponds to a value of one circumference around the rotary shaft
52
, it is not possible to set a rated voltage to high value and so if a high voltage is applied between the slider elements
55
b
,
55
c
, there occurs a problem that the resistor
54
a
is burned.
SUMMARY OF THE INVENTION
This invention has been invented in view of the aforesaid circumstances of the prior art and it is an object of the present invention to provide a variable resistor in which an electrode connected to the resistor is not be required and its rated voltage can be set high.
In order to accomplish the aforesaid object, the variable resistor of the present invention has the major feature that there are provided a resistor formed at a movable member arranged to be reciprocatable and a slider element fixed to a fixing member fixed in opposition to the movable member, slidingly in contact with the resistor to form an electrical signal generating part together with the resistor, the resistor has a first resistor, a second resistor and a third resistor extending in a reciprocating direction of the movable member and electrically independent from each other, a first resistor pattern having one end of each of the first resistor and the second resistor connected to each other, a second resistor pattern having the other end opposite to one end of the third resistor connected to the other end of the second resistor, the slider element is comprised of a first slider element, a second slider element and a third slider element slidingly contacted with the first resistor, the second resistor and the third resistor. The first, second and third slider elements slide on the first, second and third resistors through a reciprocating motion of the movable member. When the movable member moves from one end to the other end of each of the first, second and third resistors, a resistance value between the first and second slider elements is increased and a resistance value between the second slider element and the third slider element is decreased, and in turn when the movable member is moved from the other end to one end of each of the first, second and third resistors, a resistance value between the first slider element and the second slider element is decreased and a resistance value between the second slider element and the third slider element is increased.
Accordingly, since it is not necessary to form the electrodes as found in the prior art, it is possible to simplify a manufacturing stage for the variable resistor and at the same time the length of the resistor can be increased as compared with that of the prior art resistor, resulting in that a rated voltage can be set large. In addition, since the first, second and third resistors and the first and second patterns described above can be formed simultaneously at the same stage by applying a screen printing method, productivity of the variable resistor is improved.
Further, the first and third resistors having the aforesaid constitution are arranged side by side in a direction crossing at a right angle with a reciprocating motion of the movable member and formed in parallel along the second resistor.
Thus, it is possible to reduce a size of the resistor in a reciprocating direction of the movable member and correspondingly to make a small-sized variable resistor.
Further, the first and third resistors in the aforesaid constitution are arranged in opposition to each other while holding the second resistor.
Accordingly, it is possible to reduce a size of the resistor in a reciprocating direction of the movable member and attain a more small-sized variable resistor.
In addition, the first, second and third resistors and the first and second resistor patterns in the aforesaid constitution are integrally formed.
Thus, these elements can b
Kurantani Junichi
Ogawa Toshio
Takahashi Kisaburo
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Easthom Karl D.
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