The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 26, 1988
Filed:
May. 19, 1986
Alfred Wuthrich, Stafa, CH;
Walter Meier, Orselina, CH;
Cerberus AG, Mannedorf, CH;
Abstract
An intrusion detector evaluates the infrared radiation emitted by an intruder within a closely defined zone or area by means of a virtual protective curtain. Uniform sensitivity independent of incident angle of the radiation is provided by a cylindrical Fresnel lens of small thickness, which divides the field of reception into sharply defined strips or elongate zones of substantially uniform sensitivity. The longitudinal axis of this Fresnel lens defines an arcuate sector of a circle whose radius is determined by the focal length in perpendicular direction, and an infrared sensor is arranged at the circular center point, i.e., the focal point of the curved Fresnel lens. One particularly advantageous embodiment of the intrusion detector includes a double sensor configuration, equipped with several sensor elements cooperating with one or more cylindrical Fresnel lenses, thus covering a number of separate zones for simultaneous radiation detection.