摘要 |
A safety system for automatically operated sliding panel doors, specifically elevator doors, having acoustic wave transmitters and receivers arranged in a row along the moving door's leading edge. Short bursts of acoustic energy are projected both in front of the door and to one or both sides so as to "sweep" a three-dimensional space, in and near the door's path, representing a zone of potential danger to persons or objects therein. Reflected energy from persons or objects in the danger zone is usable if it is received, following each transmitted burst, during a prescribed time interval representing combinations of the doorway opening distance and other selected parameters, and usable reflections are converted to a control signal to stop and re-open the doors before they strike the endangered person or object.
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