| 摘要 |
An automatic lighting controller applies a turn-off control signal to a gate controlled power switch for switching OFF lighting when a timer circuit determines that motion activity above a threshold level has not occurred within the controlled area during a prescribed interval. A counter produces a grace period count signal and a reset count signal, with the grace period count signal occurring within a predetermined sub-interval, for example, one count cycle prior to the reset count signal. The grace period count cycle (N-1) interval is adjustable, for example, from about 0.6 second (for test purposes) to about 14 seconds. The grace period count signal enables an audio transducer which provides an audible alert that the lights are about to be switched OFF automatically. A person in the controlled area can override the impending automatic shutoff simply by initiating some motion activity during the grace period.
|
