Door and window sensors using ambient infrared
A sensor assembly for detecting open or closed state in windows and doors includes a passive infrared sensor configured to produce a change in an electrical signal based on a change in infrared radiation incident on the passive infrared sensor. A lens is operatively connected to the passive infrared sensor. At least a portion of the lens is configured to be mounted in an interface between a frame and a door or window mounted to open and close within the frame. The lens is configured to guide ambient infrared radiation to the passive infrared sensor at a first level when the door or window is closed and at a second level when the door or window is open or ajar.
1. A sensor assembly for detecting open or closed state in windows and doors comprising:
a passive infrared sensor configured to produce a change in an electrical signal based on a change in infrared radiation incident on the passive infrared sensor; and
a lens operatively connected to the passive infrared sensor, wherein at least a portion of the lens is configured to be mounted in an interface between a frame and a door or window mounted to open and close within the frame, and wherein at least a portion of the lens is a waveguide that is configured to guide ambient infrared radiation to the passive infrared sensor at a first level when the door or window is closed and at a second level when the door or window is ajar, wherein the lens includes:
a first portion housing the passive infrared sensor and including an ambient window configured to face an ambient environment; and
a second portion angled relative to the first portion, wherein the second portion is configured to be mounted in the interface between a frame and a door or window mounted to open and close within the frame, wherein the first and second portions of the lens are operatively connected to one another to direct ambient infrared radiation incident on the ambient window of the first portion, into the second portion, through the second portion to the passive infrared sensor in the first portion.
2. The sensor assembly of claim 1 , wherein the lens is configured to receive ambient infrared radiation incident thereon from a first direction, and to direct infrared radiation onto the passive infrared sensor in a second direction different from the first direction.
3. The sensor assembly of claim 2 , wherein the first and second directions are about 90° apart.
4. The sensor assembly of claim 1 , wherein the second portion of the lens includes an interface window configured to face into the interface between a frame and a door or window, wherein the interface window is configured to alter how much infrared radiation is incident on the passive infrared sensor depending on whether the door or window is ajar.
5. The sensor assembly of claim 1 , wherein at least the second portion of the lens has a thickness less than about 2 mm.
6. The sensor assembly of claim 1 , wherein the lens includes an adhesive surface configured for mounting the lens with at least a portion of the lens in the interface between a frame and a door or window mounted to open and close within the frame.
7. The sensor assembly of claim 1 , wherein the lens includes an acrylic material.
8. The sensor assembly of claim 1 , further comprising a capacitive sensor operatively connected to the lens to detect a change in capacitance based on whether the door or window is ajar to provide an additional modality of detection.
9. The sensor assembly of claim 1 , wherein the passive infrared sensor is a first passive infrared sensor, and further comprising a second infrared sensor operatively connected to the lens, wherein the second infrared sensor is oriented in a direction to receive a level of ambient infrared radiation independent of whether the door or window is ajar for adjustment of the first passive infrared sensor to account for changes in ambient infrared levels.
10. A sensor assembly for detecting state of an interface between two surfaces:
a passive infrared sensor configured to produce a change in an electrical signal based on a change in infrared radiation incident on the passive infrared sensor; and
a lens operatively connected to the passive infrared sensor, wherein at least a portion of the lens is configured to be mounted in an interface between a first surface and a second surface movable relative to the first surface, and wherein the lens is a waveguide that is configured to guide ambient infrared radiation to the passive infrared sensor at a first level when the first surface is in a first position relative to the second surface and at a second level when the first surface is in a second position relative to the second surface, wherein the lens includes:
a first portion housing the passive infrared sensor and including an ambient window configured to face an ambient environment; and
a second portion angled relative to the first portion, wherein the second portion is configured to be mounted in the interface between a frame and a door or window mounted to open and close within the frame, wherein the first and second portions of the lens are operatively connected to one another to direct ambient infrared radiation incident on the ambient window of the first portion, into the second portion, through the second portion to the passive infrared sensor in the first portion.