Plessey Handel Und Investments A.g.

David Appleby

Stephen George Porter

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 and one of the active regions are connected together in parallel and the other active region is connected in series with these two. The arrangement has full cancellation of environment effects while being partially unbalanced for infra-red detection so that isolated areas of infra-red 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.

Pyroelectric detectors

A pyroelectric detector which includes at least one pyroelectric element consisting of a pyroelectric material sandwiched between first and second electrodes, and a semiconductor chip having a field effect transistor formed on one surface thereof and having an electrical contact for the gate electrode of the transistor formed on the surface thereof, opposite to said one surface, the gate electrode contact of the chip being secured in electrical contact to the first one of the electrodes of the pyroelectric element, the size of the chip being such that a major portion of the first electrode is not covered by the chip.

Growing community of inventors

Northampton, United Kingdom

David Appleby