| 摘要 |
A safety device for accurately preventing the catching of a hand or neck of a passenger of a vehicle between a windowpane and a window sash uses a potentiosensor 20 for detecting the rotational angular position of an output shaft adapted to rotate at a slower speed by reducing the speed of a rotating shaft of a driving motor 9 for opening and closing a windowpane of a vehicle with a speed reducing mechanism 10. This potentiosensor 20 comprises a resistance track plate 21 on which circular resistance track 25a and conductor tracks 25b, 25c are formed, and a rotating plate 23 having conductive brushes 24a, 24b adapted to slide over the resistance track plate 21. The windowpane position is detected based on a resistance value outputted when the conductive brushes 24a, 24b are rotationally moved on the resistance track 25a in response to the rotating position of the rotating plate 23. The resistance track 25a is supplied with a higher voltage and a lower voltage at diametrically opposite positions, respectively, and the conductive brushes 24a, 24b are constructed so as to output voltages which are divided at a rotating angle of 180 degrees. This enables not only the detection of the windowpane with high accuracy but also the miniaturization of a power window apparatus and simplification of the construction of a circuit thereof.
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