To miniaturize a safety device for a power window, by which the pinching of a hand, a neck or the like between a window pane and a sash is detected accurately and safety control operation is executed, and to simplify constitution.
A potentiosensor 20 detecting the rotary angular position of an output shaft for a decelerating mechanism 10 decelerating the shaft of a driving motor 9 for opening a window pane for a car is installed. The potentiosensor 20 has a resistance track plate 21, on which annular ring-shaped resistance track 25a and conductor tracks 25b, 25c are mounted, and a rotary plate 23 with conductive brushes 24a, 24b slid on the resistance track plate 21, and the rotary angular position of the output shaft is detected on the basis of a resistance value output when the conductive brushes 24a, 24b are rotated and moved on the resistance track 25a in response to the rotary position of the rotary plate 23. Since the resistance track 25a is supplied with high-side voltage and low-side voltage at the opposed places of the rotary plate 23 and the conductive brushes 24a, 24b divide the voltage at the angle of rotation of 180° and output it, position sensing is carried out with high accuracy, and a power window device can be miniaturized and circuit configuration simplified.
FUKAZAWA FUSAO
TAJIMA KEIICHI
