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Motor-powered opening/closing apparatus for a window or door

  • US 4,970,446 A
  • Filed: 07/12/1988
  • Issued: 11/13/1990
  • Est. Priority Date: 07/18/1987
  • Status: Expired due to Term
First Claim
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1. A motor-powered apparatus comprising:

  • a motor serving as a power source for a motor-powered mechanism for opening/closing a window or door;

    a constraint stop circuit comprising,a comparator having an input connected to said motor for comparing an electromotive force induced at a motor terminal of said motor with a reference voltage;

    a drive transistor connected to the output of said comparator and said motor terminal and controlled to be turned on/off in response to the output of said comparator, for supplying a drive current to said motor when said electromotive force is greater than said reference voltage and cutting off said drive current when said electromotive force is less than said reference voltage;

    a shut off transistor connected to the drive transistor for making the drive transistor periodically and instantaneously turn off so as to cause said comparator to periodically compare said electromotive force with said reference voltage; and

    a circuit for forming the reference voltage which determines a motor torque when said motor is going to be stalled,a sensor for detecting clamping of a foreign object between a fixed frame and an edge of a window or door, said sensor being arranged on the fixed frame close to and along a contact line between the fixed frame and the edge of the window or the door; and

    switching means connected to said constraint stop circuit for stopping the supply of the power to said motor or inverting a polarity of the power in response to an output from said sensor.

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