| 摘要 |
An energy detecting apparatus which operates by detecting at least the position of an object or other matter positioned in space, comprises a detector (13; 23) which includes sensor means (14, 14<1>; 25) for detecting energy received along at least one path (18; 24) extending from at least one energy source (12; 22, 22<1>). A pair of energy receiving devices (14, 14<1>) or transmitting devices (22, 22<1>) have different polar characteristics and are arranged as close together as possible, being comprised in either the sensor means or the source. The arrangement is such that the sensor means transmits two signals (S, S<1>; SR, SQ<1>) to a ratiometric amplifier (20; 27) which produces another output signal alpha in which all variables are cancelled out except that which is dependent on the direction THETA ; PHI of the energy path. Continuous detection of the direction is thus obtained without other parameters such as source intensity of distance between source and detector being known. Applications of the invention to position detection, Doppler and passive infra-red motion detection, and flame detection are also described. The invention has application to security systems, including intruder alarm systems. |
