Passive infra-red intrusion sensor
First Claim
1. An infra-red lens array comprising a plurality of lenses arranged in at least one upper row comprising at least one convex lens, and at least one lower row comprising at least one cylindrical lens whose cylindrical axis is aligned substantially perpendicular to the direction of the row.
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Accused Products
Abstract
An improved infra-red lens array for use in a passive infra-red intrusion sensor, which maintains high detection capability for intruders moving in the middle and near field, and yet discriminates well between the movement of intruders and of pets in the near field. The upper part of the lens array is composed of at least one row containing convex lenses, operative to focus the far and middle field radiation of the area to be protected onto the detector of the sensor. The lower part of the array has at least one row containing cylindrical lenses, with their axes of symmetry aligned vertically, operative to focus infra-red radiation from the middle and near fields onto the detector. Each cylindrical lens focuses a vertical curtain of the protected area onto the infra-red detector. In order to ensure reduced sensor sensitivity close to the floor of the protected area, so as to provide pet movement discrimination, the cylindrical lenses are provided with spatially selective attenuation, so as to reduce their transmission factor as a function of the angle between the sensor and points on the floor.
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Citations
45 Claims
- 1. An infra-red lens array comprising a plurality of lenses arranged in at least one upper row comprising at least one convex lens, and at least one lower row comprising at least one cylindrical lens whose cylindrical axis is aligned substantially perpendicular to the direction of the row.
- 4. An infra-red lens array comprising at least one row including at least one cylindrical lens operative to provide spatially varying partial attenuation to radiation imaged by said lens.
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22. A passive infra-red intrusion sensor comprising:
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a housing;
an infra-red detector;
a lens array comprising at least one row including at least one cylindrical lens for imaging infra-red radiation onto said detector; and
optical apparatus causing spatially varying partial attenuation to radiation imaged by said at least one cylindrical lens. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 42, 43, 44, 45)
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37. A passive infra-red intrusion sensor comprising optical apparatus including a cylindrical lens arranged generally vertically causing spatially varying partial attenuation to radiation being imaged, said spatially varying attenuation being operative to reduce detection sensitivity close to floor level where a human emits lower levels of radiation, and to maintain detection sensitivity at human head and hand level, where a human emits higher level of radiation, thereby providing a lower probability of detecting a pet and a higher probability of detecting a human.
Specification