| 摘要 |
An intruder detector consists of an element of pyroelectric material having three defined regions; two being active to infra-red radiation and one being relatively inactive to infra- red radiation. The inactive region A2 and one of the active regions A1 are connected together in parallel and the other active region B is connected in series with these two. The arrangement has full cancellation of environment effects whilst being partially unbalanced for infra-red detection so that isolated areas of infrared radiation (such as an intruder) can be detected at long and short ranges. The element is used with a concave mirror for increased zonal coverage. Each of the regions of pyroelectric material has a substantially constant thickness and all of the three regions have the same thickness. <IMAGE> |
