| 摘要 |
<p>A lock release apparatus for an exit door 1 comprises a door lock 4, a beam transmitter 5 and receiver 6, a timer for releasing said lock after a predetermined delay, trigger means associated with said timer and a beam reflector means 8 affixed to an operating means 2 of the exit door. While the exit door is undisturbed the transmitter directs a beam which is reflected by the reflector means and received by the receiver. When the operating means to open the exit door is moved the beam to the receiver is broken triggering said timer to release the lock after the predetermined delay. The beam may be pulsed infrared light while the operating means may be a latch handle (Fig 2) or a push bar. The apparatus may further include an alarm and monitors to advise security staff of door and lock status. When released the lock may be adapted to remain disengaged until reset.</p> |
