Safety device for power window

Abstract

A power-window safety device which includes an annular magnet mounted on a rotary shaft ( ) of a drive motor ( ) for opening and closing a window glass of an automotive vehicle, and a magnetic flux sensor ( ), disposed facing the annular magnet ( ), for sensing a change of a magnetic flux developed from the annular magnet ( ), which change in flux is caused by rotation of the rotary shaft ( ). The magnetic flux sensor includes Hall ICs ( A and B). An operational element ( A, B) performs a process of linearly approximating a sinusoidally varying voltage output from a Hall element ( A, B) which is provided in association with the operational element, and produces an output voltage (VA, VB) thus processed. Every angular position of the rotary output shaft, or every opening/closing position of the window glass, is detected over the range of one complete rotation on the basis of the output voltages (VA and VB) that are generated through the rotation of the rotary shaft ( ). A safety control operation is carried out, to prevent an object from being caught, on the basis of the detected position.