Chopped passive infrared sensor apparatus and method for stationary and moving occupant detection
AssigneeThe Research Foundation for The State University of New York
InventorsYa Wang, Haili Liu, Kevin Wang
Life of this patent
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Abstract
A chopped PIR (C-PIR) sensor is capable of detecting both stationary and moving objects with a high degree of accuracy using a narrow infrared semi-transparent chopper to temporally shutter incident radiation received by pyroelectric sensing elements. Demonstrating a field of view of 110° (horizontal) and 90° (vertical), the C-PIR sensor can detect stationary objects located within 4 m of the sensor, and moving objects located within 8 m of the sensor with 100% accuracy.
Claims19
A pyroelectric IR sensor comprising:
- a first pyroelectric sensing element for detecting infrared radiation emitted from an object;
- a Fresnel lens disposed over a surface of the pyroelectric sensing element;
- and
- an optical chopper for intermittently intercepting the infrared radiation from being incident onto said first pyroelectric sensing element, the optical chopper disposed between the sensing element and the Fresnel lens.
A method of detecting an occupant using a pyroelectric IR sensor comprising:
- collecting infrared radiation using a first pyroelectric sensing element, wherein prior to the infrared radiation being incident upon a surface of the first pyroelectric sensing element the infrared radiation passes through a Fresnel lens and an optical chopper,
- wherein the infrared radiation passes through the Fresnel lens prior to passing through the optical chopper.
A pyroelectric IR sensor comprising:
- a first pyroelectric sensing element for detecting infrared radiation emitted from an object;
- a second pyroelectric sensing element positioned adjacent the first pyroelectric sensing element, the second pyroelectric sensing element detecting the infrared radiation emitted from the object;
- a Fresnel lens disposed over the first pyroelectric sensing element and the second pyroelectric sensing element;
- and
- an optical chopper positioned between and substantially separating the first pyroelectric sensing element and the second pyroelectric sensing element and the Fresnel lens, the optical chopper including:
- a first end mounted on a pivot, and
- a second end formed opposite the first end, the second end positioned adjacent to the first pyroelectric sensing element and the second pyroelectric sensing element,
- wherein the optical chopper is configured to oscillate the second end between covering the first pyroelectric sensing element and the second pyroelectric sensing element to intermittently intercepting the infrared radiation from being incident onto the first pyroelectric sensing element or the second pyroelectric sensing element, and
- wherein the optical chopper includes at least one of a length or a width that prevents both the first pyroelectric sensing element and the second pyroelectric sensing element from being completely covered simultaneously during the oscillation.
Dependencies are inferred from the claim text.