Personnel intrusion detecting device

• US 3,237,105 A
• Filed: 05/09/1962
• Issued: 02/22/1966
• Est. Priority Date: 05/09/1962
• Status: Expired due to Term

• Current Assignee: Henry P. Kalmus
• Original Assignee: Henry P. Kalmus
• Inventors: Kalmus, Henry P.
• Application Number:
  US04/193,407
• Time in Patent Office: 1,385 Days
• US Class Current: 340/562
• CPC Class Codes: G08B 13/2491 Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field

Claims

1. AN INTRUSION WARNING SYSTEM OF THE CAPACITIVE TYPE FOR INDICATING THE PRESENCE OF AN INTRUDER IN A GIVEN UNOBSTRUCTED AREA COMPRISING A SINGLE TRANSMITTING ELECTRODE ON ONE SIDE OF THE GIVEN AREA TO BE PROTECTED, AN ELECTRIC OSCILLATOR CIRCUIT CONNECTED BETWEEN SAID ELECTRODE AND GROUND FOR PRODUCING A QUASI-STATIONARY FIELD BETWEEN SAID ELECTRODE AND GROUND;

A SINGLE RECEIVING ELECTRODE ON THE OTHER SIDE OF THE AREA TO BE PROTECTED SO ARRANGED THAT AN OBJECT TRAVERSING SAID AREA PASSES THROUGH A DIRECT LINE BETWEEN SAID TWO ELECTRODES;

SAID OSCILLATOR CIRCUIT OPERATING AT A WAVE LENGTH WHICH IS VERY LARGE COMPARED TO THE DISTANCE BETWEEN THE ELECTRODES;

SIGNAL AMPLIFYING MEANS CONNECTED TO SAID RECEIVING ELECTRODE FOR AMPLIFYING QUASI-STATIONARY FIELD SIGNALS RECEIVED FROM SAID TRANSMITTING ELECTRODE, AND DIRECT INDICATING MEANS FOR DETECTING AND INDICATING CHANGES IN THE RECEIVED QUASISTATIONARY FIELD SIGNALS DUE TO AN INTRUDING BODY IN SAID AREA.