DETECTOR SYSTEM

• US 3,725,888 A
• Filed: 04/05/1971
• Issued: 04/03/1973
• Est. Priority Date: 04/05/1971
• Status: Expired due to Term

• Current Assignee: Graviner Limited
• Original Assignee: Elias E. Solomon
• Inventors: Solomon, Elias E.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/131,222
• Time in Patent Office: 729 Days
• Field of Search: 340/258R,258A,258B,258D,228S,420
• US Class Current: 340/522
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G08B 13/189 using passive radiation detection systems
• CPC Class Codes: G08B 13/24 by interference with electromagnetic field distribution
• CPC Class Codes: G08B 13/2494 by interference with electro-magnetic field distribution combined with other electrical sensor means, e.g. microwave detectors combined with other sensor means

Abstract

An intruder detector system that utilizes both a Doppler effect detector system and an optical detector system monitoring the same space. An alarm output signal produced by either detector under alarm conditions is prevented from activating an alarm unless the other detector also is producing an alarm signal.

Claims

1. An intruder detector system, comprising first and second detector devices arranged to monitor substantially the same confined space, each of said detector devices being responsive to the entry of an intruder to provide an output signal, one of said detectors being responsive to a Doppler effect to produce its output signal, the other being responsive to a change in light intensity to produce its output signal, means receiving the output of each of said detectors, said means producing an alarm output signal only when said detectors produce an output signal simultaneously.

2. A detector system comprising a detection device of the type utilizing a change in frequency to cause an alarm output signal and a detector device utilizing a rate of change in light intensity to cause an alarm output signal, said detector devices being arranged to monitor substantially the same confined space, an AND gate, the output of said detectors being connected to said AND gate, the output of said AND gate being connected to an alarm actuating device, whereby the AND gate transmit a signal to the alarm actuating device only if both alarm devices produce an alarm output signal simultaneously.

3. A detector system, comprising a first detector producing an alarm signal output in response to a change in frequency between a transmitted signal and a received signal, and a second detector arranged to monitor at least a portion of a confined space being monitored by the first detector, said second detector being responsive to a predetermined change of light intensity to cause an alarm signal output, and means preventing said alarm signal output from either detector from actuating an alarm unless the other detector also simultaneously generates an alarm signal output.