Theft alarm for shoplift prevention

• US 3,253,270 A
• Filed: 08/02/1963
• Issued: 05/24/1966
• Est. Priority Date: 08/02/1963
• Status: Expired due to Term

• Current Assignee: Frank Downer
• Original Assignee: Frank Downer
• Inventors: Downer, Frank
• Application Number:
  US04/299,513
• Time in Patent Office: 1,026 Days
• US Class Current: 340/568.4
• CPC Class Codes: G08B 13/1454 Circuit arrangements thereof

Claims

1. A THEFT ALARM SYSTEM FOR THE PROTECTION OF A PLURALITY OF MOVABLE OBJECTS, COMPRISING AN ELECTRIC ALARM, A SOURCE OF ELECTRIC POWER, A CIRCUIT CONNECTED TO SAID SOURCE INCLUDING A NUMBER OF INDEPENDENTLY MOVABLE LONG TWO-CONDUCTOR LINES IN SERIES WITH SAID SOURCE AND WITH EACH OTHER, EACH OF SAID LINES HAVING A FIXED END AT WHICH THE TWO CONDUCTORS ARE CONNECTED TO THE CIRCUIT, AND A FREE END AT WHICH THE TWO CONDUCTORS ARE CONNECTED TO EACH OTHER THROUGH A SMALL FIXED RESISTOR ELEMENT, THE TWO CONDUCTORS BEING SPACED AT THE FREE END TO PROVIDE A LOOP THROUGH WHICH THE LINE CAN BE PASSED AROUND A PORTION OF A MOVABLE OBJECT TO BE PROTECTED, ALL OF SAID LINES AND RESISTORS BEING IN THE SAME CIRCUIT TO PROVIDE A DEFINITE VALUE OF ELECTRIC CURRENT FLOW IN THE CIRCUIT, AND SENSING MEANS RESPONSIVE TO A CHANGE IN SAID VALUE OF CURRENT FLOW CORRESPONDING TO THE REMOVAL OF EVEN ONE OF SAID RESISTORS FROM THE CIRCUIT TO OPERATE SAID ELECTRIC ALARM DEVICE, SAID FIXED END COMPRISING A JACK HAVING TWO TERMINALS, SAID CIRCUIT HAVING A TWO-TERMINAL SOCKET FOR RECEIVING SAID JACK, AND A RESISTANCE ELEMENT NORMALLY CONNECTED IN SAID CIRCUIT ACROSS THE TERMINALS OF SAID SOCKET BY CIRCUIT MEANS INCLUDING MOVABLE CONTACT MEANS WHICH ARE NORMALLY ENGAGED, AND ARRANGED TO BE DISCONNECTED FROM THE CIRCUIT, BY DISENGAGEMENT OF SAID CONTACT MEANS, WHEN THE JACK IS PLUGGED INTO THE SOCKET, SAID RESISTANCE ELEMENT HAVING THE SAME VALUE AS SAID RESISTOR, WHEREBY PLUGGING THE JACK INTO THE SOCKET DOES NOT CHANGE THE ELECTRICAL VALUE OF THE CIRCUIT.