| 摘要 |
876,998. Measuring distances by sound waves. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. July 2, 1959 [July 3, 1958], No. 21378/58. Drawings to Specification. Class 40(7) Relates to sonic or ultrasonic apparatus for collision avoidance between two relatively moving bodies. According to the invention one body transmits a beam along an axis inclined to the direction of relative movement and a receiver is so positioned that it receives the beam only when the bodies are less than a predetermined distance apart. The received signal may be used to actuate an audible alarm or to prevent further relative movement. In one embodiment a crane carries a transmitter and a receiver and another crane, or a wall, carries a sound reflector, Fig. 1 (not shown); or each body carries a transmitter, receiver and reflector, Fig. 3 (not shown). In a further embodiment the transmitter is mounted on one body and the receiver on the other, Fig. 4 (not shown). A frequency of 11 kc./s. is preferred. Specification 779,658 is referred to. |
