Patent ID: 7830107
Filing Date: 2010-11-09
Classification: E05F,E05Y,H02H

Abstract:
1. A safety device for power window, characterized by having: a raising/lowering motor that raises or lowers a window glass of a vehicle, an operational switch that provides a positive or negative rotation instruction to the raising/lowering motor, a pulse generator that generates repetitive pulses in accordance with the amount of rotation of the raising/lowering motor, a window position counter that counts the pulses generated by the pulse generator to obtain opening information of the window glass, a pulse width detector that detects pulse width of each pulse generated by the pulse generator, a calculation unit that extracts predetermined, particular two kinds of pulse width from a plurality of kinds of pulse width detected by the pulse width detector, and calculates a change rate between the extracted, two kinds of pulse width while relating the change rate to window position information given by the window position counter, a storage unit that stores the change rate of pulse width calculated by the calculation unit in a certain reference setting condition, the change rate being related to the window position information, and a control unit that compares stored values of the change rate of pulse width stored by the storage unit, the change rate being related to the window position information, to calculation values of the change rate of pulse width calculated by the calculation unit respectively during raising operation of the window glass, the change rate being related to the window position information, and when the total of differences between both change rates of pulse width exceeds an allowable value, drives the raising/lowering motor in a direction of opening the window glass irrespectively of a state of the operational switch.