Passive infrared detector
First Claim
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1. An infrared detector, comprising:
- a pyroelectric detector equipped with a window and having first and second sensing elements disposed on a first side of said window;
a diffusely reflective septum disposed on a second side of said window; and
a Fresnel lens array disposed on said second side of said window.
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Abstract
An infrared detector (301) is provided which comprises a pyroelectric detector (303) having first and second sensing elements (345), an aperture stop (311), and a Fresnel lens array (305). The detector may be used as a passive infrared sensor unit for detecting intrusion into large openings.
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Citations
20 Claims
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1. An infrared detector, comprising:
a pyroelectric detector equipped with a window and having first and second sensing elements disposed on a first side of said window; a diffusely reflective septum disposed on a second side of said window; and a Fresnel lens array disposed on said second side of said window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An infrared detector, comprising:
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a window; first and second sensing elements disposed on a first side of a window; a diffusely reflective septum disposed on a second side of a window; and a Fresnel lens array; wherein the Fresnel lens array has a finite focal length. - View Dependent Claims (18, 19)
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20. A method for detecting an intrusion, comprising:
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disposing an infrared detector adjacent to an opening such that the infrared detector is positioned to detect the movement of an infrared emitting body across the opening, wherein the infrared detector includes (a) a pyroelectric detector equipped with a window and having first and second sensing elements disposed on a first side of said window, (b) a diffusely reflective septum disposed on a second side of said window, and (c) a Fresnel lens array disposed on said second side of said window; monitoring the opening with the infrared detector for the movement of an infrared emitting body across the opening; and generating an alarm signal when the movement of an infrared emitting body across the opening is detected.
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Specification