| 摘要 |
PROBLEM TO BE SOLVED: To facilitate adjusting the range of alert of a passive infrared sensor without using a complicated configuration. SOLUTION: The passive infrared sensor comprises two light collecting optical system, the first optical system 11 and second optical system 21, and these two light collecting optical systems are configured by a plurality of Fresnel lenses. The first element 12 and second element 22 are disposed corresponding to the first optical system 11 and second optical system 21 respectively. Because of these elements and light collecting optical systems, the detecting zone is arranged in the zone forming surface as predetermined fashion. For adjustment of the range of alert, the desired Fresnel lenses of the first optical system 11 and/or second optical system 21 are masked with masking member M. COPYRIGHT: (C)2006,JPO&NCIPI |
