(57) A rotary variable resistor comprising a resistive film (33) formed on an insulating
substrate (302), a current collecting conductive member (36) disposed in such a manner
as to be concentric with the resistive film (33) and to be spatially isolated from
the resistive film (33) and the lead members (34) thereof (33), a circular arc shaped
auxiliary conductive member (39) formed in such a manner as to be concentric with
the resistive film (33), and to be spatially isolated from the resistive film (33),
the current collecting conductive member (36) and the lead members (34,37) of the
patterns (33,36), also to cover a larger angular range than the angular opening of
the resistive film (33), a first brush (31) made of an elastic metal plate and fixed
to an operation shaft which is repeatedly rotatable, also having first contact portions
(42) which respectively elastically contact to the resistive film (33) and to the
current collecting conductive member (36), wherein the first brush (31) forms a first
resistor unit (43) together with the resistive film (33) and the current collecting
conductive member (36), and, a second brush (32) made of an elastic metal plate and
fixed to the operation shaft in such a manner as to be electrically isolated from
the first brush (31), also having second contact portions (44) which respectively
elastically contact to the resistive film (33) and to the auxiliary conductive member
(39) in the rotational angular range of the operation shaft, in which a predetermined
output voltage is unobtainable from the first resistor unit (43), wherein the second
brush (32) forms a second resistor unit (45) together with the resistor film (33)
and the auxiliary conductive member (39). The above structure simplifies the pattern
structure of a resistor board (30) and decreases the number of terminals, also simplify
the production process.
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