Patent ID: 7196486

Claim:
An apparatus for detecting an obstacle to a power regulated window to be opened and closed by a motor comprising: current detecting means for detecting a momentary value of load current flowing through the motor; pulse-signal outputting means for outputting a pulse signal having a longer pulse interval correspondingly to retardation of rotating speed of the motor, said pulse-signal outputting means comprising: a ripple/pulse converting portion which detects a component of rotating speed of the motor by detecting ripples of input current flowing through the motor, and converts the rotating speed of the motor to pulses with variable periods in response to the rotating speed of the motor, and outputs the pulses with variable periods; and a one-shot timer which inputs the pulses with variable periods and outputs pulses with a constant pulse width synchronizing with rising edges of the pulses with variable periods as a control signal; average-value generating means for generating and outputting an average value, the average value having a rate-of-change of an amplitude that is variable in response to a time constant, wherein the time constant has been set to have a time length-corresponding to a period of the pulse signal, the average value being a reference value for judging when the load current value of the motor exceeds a predetermined value of over-load current; and comparing means for judging whether or not the momentary value detected by the current detecting means exceeds the average value outputted by average-value generating means by comparing the momentary value with the average value, wherein existence of a bitten obstacle is detected by a judging result of the comparing means.