Masked passive infrared intrusion detection device and method of operation therefore
US5818337A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 13, 1997 |
| Grant date | Oct 6, 1998 |
| Priority date | — |
| Expiry date | Jan 13, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/191
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A passive infrared intrusion detection device uses a dual element pyroelectric detector and a housing for surrounding and containing the dual element pyroelectric detector. The housing has a plurality of Fresnel lens elements for gathering infrared radiation from a "look down" volume of space and for focusing the gathered infrared radiation onto the pyroelectric detector. A mask positioned between the plurality of Fresnel lens elements and the detector partially occludes the gathered infrared radiation from the Fresnel lens elements to one of the elements of the dual element pyroelectric detector creating an imbalance in the signal thereby preventing common mode rejection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.