Electricity: motive power systems – Automatic and/or with time-delay means – Movement – position – or limit-of-travel
Patent
1997-07-07
1998-07-14
Ro, Bentsu
Electricity: motive power systems
Automatic and/or with time-delay means
Movement, position, or limit-of-travel
318 16, 318286, 318468, 318480, E05F 1510
Patent
active
057809879
ABSTRACT:
A movable barrier or garage door operator has a barrier drive for moving the movable barrier or garage door between open and closed positions. Motion of the barrier is detected by a tachometer connected to the barrier drive or by upper and lower barrier travel limit switches. A test is made to determine if the barrier has been commanded to be in a closed state and to determine if a preselected time interval has elapsed following closure of the barrier. When both of those conditions are present and the door is moved upward without authorization an alarm signal is generated and can signal the barrier drive to apply a closing force. The timer prevents the barrier from being closed on a person or obstacle during normal operation and prevents injury. An obstacle detector also prevents unwanted closure on an obstacle.
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Fitzgibbon James J.
Moravec John V.
Ro Bentsu
The Chamberlain Group, Inc.
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