METHOD AND APPARATUS FOR DETECTING THE THEFT OF ARTICLES

• US 3,859,652 A
• Filed: 06/26/1972
• Issued: 01/07/1975
• Est. Priority Date: 06/26/1972
• Status: Expired due to Term

• Current Assignee: Edward S. Wainwright, Kenneth Clarkson, Roger L. Hall
• Original Assignee: Edward S. Wainwright, Kenneth Clarkson, Roger L. Hall
• Inventors: Hall, Roger L., Wainwright, Edward S., Clarkson, Kenneth
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/266,130
• Time in Patent Office: 925 Days
• Field of Search: 340/258R,280,224 325/16,21,185,186 343/6.8R
• US Class Current: 340/572.3
• CPC Class Codes: G08B 13/2414 using inductive tags
• CPC Class Codes: G08B 13/2434 Tag housing and attachment details

Abstract

The theft of articles or goods maintained in a vending place such as a department store having at least one exit passageway is prevented by affixing thereto a preferably small detection element comprising a receiver of first predetermined frequency, a transmitter of second predetermined frequency, and power supply means coupled from said receiver and capable of disabling said transmitter. At the authorized checkout area of the store there is disposed a relatively high power transmitter of first predetermined frequency capable of preferably permanently disabling the power supply means and in turn said transmitter of second predetermined frequency of the detection element. In one preferred embodiment the power supply means includes a rectifier circuit which is destroyed (burned out and thus opened) when the detection element comes within predetermined proximity to the high power transmitter at the checkout area. At the exitway there is disposed a transmitter of first predetermined frequency and a receiver of second predetermined frequency which only detects a signal when the power supply means has not been disabled at the authorized checkout area whereby an alarm signal is generated.

Claims

1. A system for detecting the unauthorized removal of articles from an enclosure having a checkout area and a passageway through which said articles may be moved, said system comprising;

a transmitter of a signal of first signal characteristic disposed at said passageway, a receiver of a signal of second signal characteristic disposed at said passageway and being non-responsive to a signal of first signal characteristic, means for establishing an alarm condition when said receiver receives a signal of second signal characteristic, a detection signal attached to the article and comprising a receiver of a signal of first signal characteristic, a transmitter of a signal of second signal characteristic, and means responsive to a signal, of a level less than a predetermined threshold level, from said receiver of a signal of first signal characteristic for providing power to said transmitter of a signal of second signal characteristic, a power transmitter of a signal of first signal characteristic disposed at said checkout area for establishing a signal of a level greater than said predetermined threshold level from said receiver of a signal of first signal characteristic to thereby inhibit the providing of power to said transmitter of a signal of second signal characteristic when said article is at said checkout area, whereby said receiver of a signal of second signal characteristic receives a signal to thereby establish an alarm condition when an unauthorized removal of said article has occurred, and does not receive a signal when an authorized removal has occurred, said receiver of first characteristic comprising a tank circuit and said transmitter of said second characteristic comprising a tank circuit, said power providing means including a transistor having an input electrode and an output electrode, means for biasing the transistor including a resistor coupled to the input electrode of the transistor, a diode coupling from the output electrode of the transistor to one of the tank circuits and capacitance means coupling from the output electrode of the transistor to both tank circuits, each said tank circuit including an inductor defining part of the tank circuit and forming an antenna means for transmitting or receiving signals.

2. The system of claim 1 comprising a demodulator associated with said receiver of a signal of second signal characteristic.

3. The system of claim 2 comprising means positioned adjacent the checkout area for registering a total count of each article passing through the checkout area.

4. The system of claim 3 wherein said means for registering includes an accumulator means.

5. The system of claim 1 wherein the anode of said diode couples to the output electrode and the cathode of said diode connects to the receiver tank circuit.

6. The system of claim 1 wherein said detection element comprises a modulator coupling to said transmitter of a signal of second signal characteristic and means for coupling power to said modulator from said power providing means of said detection element.