| 摘要 |
PCT No. PCT/GB89/00051 Sec. 371 Date Jul. 18, 1990 Sec. 102(e) Date Jul. 18, 1990 PCT Filed Jan. 19, 1989 PCT Pub. No. WO89/06806 PCT Pub. Date Jul. 27, 1989.A direction sensitive energy detecting apparatus characterized by having a pair of energy receiving and transmitting devices of different polar characteristics and so disposed that they define together one end of a path in such a way as to be coincident with each other; with the sensor being adapted to give two first outputs at least one of which is variable as a function of the direction of the path and the detector having ratiometric means for generating a second output which is a function of the ratio of the two first outputs and is variable only in response to changes in direction.
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