| 摘要 |
A passive infra-red, pet immune intruder detector includes upper and lower fields-of-view or zones. The detector is less sensitive to infra-red targets in the lower zones, compared to the upper zones, and the alarm threshold is set slightly above the level required to detect humans in the lower zones. Animals, which do not have access to the upper more sensitive zones are not detected in the lower relatively insensitive zones. The detector includes pyroelectric sensing elements and multi-faceted optics for directing infra-red energy onto the sensing elements from at least one lower zone, intercepting the floor plane, and at least one upper zone, extending entirely above the floor plane. The facet defining the lower zone focuses infra-red energy onto the sensing elements less efficiently than the facet defining the upper zone.
|
