| 摘要 |
A multipurpose detector, eg for fire, intrusion and activity detection, comprises an array of passive infrared detector elements (14) and a plurality of spectral filters (29) and lenses (38, 39) which are selectable, eg by rotation of an indexed wheel (13), to permit detection of a range of event types that usually require individual detectors with specific spectral/optical designs. A broad bandpass lens may be used to detect any changes due to people or flames, then a 4.3žm filter used to confirm the presence of flame flicker, or wide and narrow angle lenses each with 5.5žm long wave pass filters used to confirm the presence of people using spatial information.
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