| 摘要 |
PROBLEM TO BE SOLVED: To provide a rheostat which can increase voltage change width. SOLUTION: First to fourth resistors 61-64 and first to sixth conductors 65-70 are printed on a PC board 2 of a rheostat. The first to fourth resistors 61-64, the second to fourth conductors 66-68, a bend part 65b of the first conductor 65 and a bend part 69b of the fifth conductor 69 are printed on the same circle. A ring part 72 of the sixth conductor 70 is annular. A first sliding part of a sliding member slides along the ring part 72, and a second sliding part slides along a virtual circle formed by the first to fourth resistors 61-64. In each of the ranges in which an operation angle is 0-θ1,θ2-θ3,θ4-θ5,θ6-θ7 andθ8-θ9, a voltage ratio is constant. In each of the ranges, in which the operation angle isθ1-θ2,θ3-θ4,θ5-θ6 andθ7-θ8, the voltage ratio changes. Since the ranges where the voltage ratio becomes constant are arranged, the voltage change width can be increased in the ranges (especially inθ5-θ6), except for the ranges of a constant voltage ratio.
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