| 摘要 |
<p>An ultrasonic sensor system for automatic door openers of a swinging door type has at least one and preferably three microprocessor (45) controlled ultrasonic beam transducers (40, 41) for projecting expanding unidirectional ultrasonic beams in a detection zone SDZ in the path of the swinging door and for converting reflected single multiple path signals into an acoustical image of objects in the selected detection zone. This acoustical image is stored and compared with a later acoustical image of an object in the detection zone and used to signal a lack of correlation between the first and second acoustical images to produce a signal preventing operation of the door opening. Aspect ambiguities and problems of acoustic "transparency" are avoided by using direct multiple path reflections of more than one ultrasonic beam transducer projecting crossing beams and which have their signals multiplexed, controlled, and processed by a single computer microprocessor chip (45).</p> |
