Passive infrared detector.

摘要

A passive infrared detector including an optical collector (1A) releasably attached to a base (20) with a sensor (30) on which incident infrared radiation directed through the optical collector (1A) is focused. The sensor (30) is held by a joint member (40) which is pivotally supported on the base (20) and to which said optical collector (1A) is releasably attached by means of a magnet ring (5), whereby the optical collector is rotatable together with the joint member (40) relative to the base (20) for adjustment of its angular position and the optical collector can be alone replaced as necessary without having to replace the base (20), the sensor and its associated electric circuitry (31).