OPTICAL INTRUSION ALARM SYSTEM

• US 3,739,372 A
• Filed: 10/27/1971
• Issued: 06/12/1973
• Est. Priority Date: 10/27/1971
• Status: Expired due to Term

• Current Assignee: Gabor Schlisser, Julius R. Insler
• Original Assignee: Gabor Schlisser, Julius R. Insler
• Inventors: Schlisser, Gabor, Insler, Julius R.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/192,926
• Time in Patent Office: 594 Days
• Field of Search: 340/258B,228S 250/221
• US Class Current: 340/556
• CPC Class Codes: G08B 13/183 by interruption of a radiation beam or barrier

Abstract

An intrusion alarm system comprises a pair of light sources which produce overlapping light beams that effectively cover the entire area being protected. When either of the beams is interrupted by an intrusion, an alarm is caused to be actuated. In the embodiment of the invention here described, one of the light sources acts as a master unit directed toward a first array of detectors and the second light source directed at a second array of detectors acts as a transponder unit. When each of the detectors in the first array receives light from the master unit, the second source is turned on. The alarm is actuated whenever one of the second array of detectors fails to receive a light beam from the transponder unit.

Claims

1. An intrusion warning system for providing an indication of an intrusion into a protected area, said area being defined by first and second boundaries, said system comprising a first beam source, a first array of detectors located at one of said boundaries and in optical communication with said first beam source, a second beam source, means coupled to said first array of detectors and to said second beam source for disabling the latter whenEver radiation from said first beam source is interrupted from one of said first array of detectors, a second array of detectors located at an opposite one of said boundaries and in optical communication with said second beam source, alarm means, and means coupled between said second detector array and said alarm means for actuating the latter whenever radiation from said second beam source to one of said second detector arrays is interrupted.

2. The system of claim 1, further comprising means respectively interposed between said first and second beam sources and said first and second detector arrays for shaping the output of said first and second sources into first and second beams that substantially completely cover said area.

3. The system of claim 2, in which said beam shaping means includes means for causing adjacent portions of said first and second beams to overlie one another at the central portion of said area.

4. The system of claim 3, in which said beam shaping means include means for developing the patterns of each of said first and second beams into an approximate triangular configuration.

5. The system of claim 4, in which said area has a transverse dimension D and a vertical dimension d, the base angle Alpha of said triangular beams being approximately equal to tan 1 d/D.