EP0670562A1

EP0670562A1 - Resonant tag label detection system and method utilizing multiple frequency response

Info

Publication number: EP0670562A1
Application number: EP95850044A
Authority: EP
Inventors: John R. Pennace; Frank A. Mcconville
Original assignee: Flexcon Co Inc
Current assignee: Flexcon Co Inc
Priority date: 1994-03-01
Filing date: 1995-02-28
Publication date: 1995-09-06
Also published as: CN1129333A; JPH0883384A

Abstract

A security system and method for detecting unauthorized removal of items at an exit from a control area. The system includes labels applied to the items, the labels including a plurality of circuit elements, each circuit element being responsive to a different frequency. The labels are modifiable from an initial condition in which all of the circuit elements are actively responsive to their respective frequencies, to a live condition in which at least one but not all of the circuit elements is deactivated and rendered non-responsive to its respective frequency. The labels are also modifiable from the live condition to a dormant condition in which at least one additional circuit element is deactivated and rendered non-responsive to its respective frequency. Different frequencies are generated at the exit of the monitored area, to which said plurality of circuit elements are responsive so as to induce frequency responses by the circuit elements which remain activated. A control unit is responsive to the frequency responses generated by labels in the live condition for generating a control signal.

Description

BACKGROUND OF THE INVENTION

The invention relates to resonant tag labels which are used in electronic article surveillance and identification systems.
Conventional electronic article surveillance systems are utilized widely as an effective deterrent to unauthorized removal of items from specified surveillance areas. In surveillance systems of this type, articles to be monitored are provided with resonant tag labels which are used to detect the articles when the articles pass through a surveillance zone. The surveillance zone typically comprises an electromagnetic field of a predetermined frequency generated in a controlled area. The tag label resonates at the frequency of the electromagnetic field. The resonant frequency is detected by the system and provides an alarm indicating the presence of the label and, therefore, the article. For deactivation, either a strong surge current is induced in the resonant tag label or the circuit is mechanically disrupted in order to produce a short-circuit. Examples of conventional resonant tag labels and systems which detect them include U.S. Pat. Nos. 4,598,276, 5,214,410, 4,843,404, 5,241,299, 4,876,555, 4,900,386, 3,913,219, and 4,970,495, all of which are herein incorporated by reference.
Unfortunately, conventional resonant tag detection systems preclude the manufacturer's packaging source of an item from applying the label prior to the item being sent to a retail distributor. This is due in part to the fact that many retail distributors are not equipped to either detect or deactivate preapplied resonant tag labels on items. If an active resonant tag were applied at the packaging source of an item, which was subsequently purchased, for example, or legitimately removed from a retail distributor not equipped to deactivate the tag, possible problems could ensue. For instance, if the item is inadvertantly brought within a monitored area of a different retail distributor which is equipped to detect resonant tags, the still active tag on the item could be erroneously detected as an unauthorized removal of goods when the item is again removed from the equipped retailer. Despite these problems, it remains desirable in terms of cost and efficiency for the packaging source, rather than at the retail level, to apply resonant tag labels to items desired to be monitored. It is therefore an object of the present invention to provide a resonant tag label which would accommodate transport of items having tags applied thereto between areas which are equipped to detect resonant tags and those areas which are not.
It is a further object of the present invention to provide a resonant tag label which can be applied to all packaged items and which is activated only by those equipped to do so.

SUMMARY OF THE INVENTION

A security system and method for detecting unauthorized removal of items at an exit from a control area. The system includes labels applied to the items, the labels including a plurality of circuit elements, each circuit element being responsive to a different frequency. The labels are modifiable from an initial condition in which all of the circuit elements are actively responsive to their respective frequencies, to a live condition in which at least one but not all of the circuit elements is deactivated and rendered non-responsive to its respective frequency. The labels are also modifiable from the live condition to a dormant condition in which at least one additional circuit element is deactivated and rendered non-responsive to its respective frequency. Different frequencies are generated at the exit to which said plurality of circuit elements are responsive so as to induce frequency responses by the circuit elements which remain activated. A control unit is responsive to the frequency responses generated by labels in the live condition for generating a control signal.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a resonant tag label with multiple frequency response capability for use in the detection system of the present invention;
Fig. 2 shows a functional block diagram of the resonant tag detection system in accordance with the present invention;
Fig. 3 shows an operational flow chart of the detection system in accordance with the present invention; and
Fig. 4 shows a perspective view of the construction of an exemplary resonant tag label for use with the detection system of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

With reference to Fig. 1, an exemplary embodiment of a resonant tag label 10 is shown. The label 10 is constructed in a planar manner, for example in a row as illustrated, to include adjacently disposed label segments 12, 16 having respective tuned antenna circuits 14, 18. Each of the antenna circuits is configured in accordance with conventional label construction techniques, for example as described in any of the disclosures mentioned heretofore, or preferably as described with reference to copending U.S. Pat. App. Ser. No. Unknown, entitled Resonant Tag Label and Method of Making Same, filed ?. The resonant tag label 10 is therefore configured to be responsive to a plurality of frequencies. For illustrative purposes, the invention herein will be described with respect to a resonant tag label which is responsive to two distinct frequencies. Accordingly, antenna circuit 14 is responsive to frequency F₁ and antenna circuit 18 is responsive to frequency F₂.
With reference now to Figs. 2, a resonant tag label detection system 20 in accordance with the present invention is described. Initially, the system is dependent upon the application of the resonant tag label 10 to items 22 which are to be monitored. The antenna circuits 14, 18 associated with the label 10 are selectively deactivated by a deactivation devices 24 and 25, one associated for each frequecy of the antenna circuits. The deactivation devices, for example, are high power radio frequency transmitters which when operated proximate to an antenna circuit, the antenna circuit is rendered inoperable. Alternatively, the deactivation devices operate to mechanically engage the label 10 so as to physically damage the antenna circuits, thus rendering the antenna circuit inoperable.
A radio frequency transmitter unit 26 is disposed preferably near an exit of the area which is being monitored. The transmitter unit is operable for creating a multiple frequency field adjacent the exit area. For the example illustrated, the transmitter unit 26 generates two distinct frequencies, F₁ and F₂, to correspond to the antenna circuits associated with the label 10 which are responsive to these frequencies.
A radio frequency receiver unit 27 is correspondingly disposed adjacent the monitored area. The receiver unit is preferably operable for monitoring for the specific frequency responses associated with the antenna circuits of the resonant tag label 10.
It will be appreciated by those of skill in the art that the transmitter unit 26 and receiver unit 27 may alternatively include a single frequency transceiving unit. Once the receiver unit 27 receives the predetermined sequence of frequency responses from the resonant tag label, a control signal is generated corresponding to the label status. In accordance with a predetermined frequency response from the resonant tag label, the control signal is provided to an alarm unit 28 for providing an indication of an alarm condition.
A preferred operational sequence of the system 20 is illustrated in Fig. 3. Preferably, the system 20 is operational for providing an alarm signal in response to the receiver unit 27 receiving only one frequency response from the resonant tag label 10. Accordingly, this will accommodate the application of resonant tag labels 10 to all items at the packaging source (step 300). Thus, according to the exemplary operation illustrated, the resonant tag label includes antenna circuits which are responsive to the two distinct frequencies, F₁ and F₂.
In the example provided for illustrative purposes, the item 22 with the applied resonant tag label 10 is furnished to a controlled retail distributor. Once this item is inventoried at the controlled retailer, one of the antenna circuits of the resonant tag label 10 is deactivated to create a live status (step 302). When the item is purchased or rendered otherwise suitable for an authorized removal from the monitored area, the second of the antenna circuits is deactivated in order to create a disabled status (step 304). Thus, when the item 22 and resonant tag label 10 are subjected to the multiple frequency field at the exit of the monitored area, no frequency responses are induced by the antenna circuits. Accordingly, an alarm condition is not indicated (step 308). However, if an unauthorized removal of the item occurs, thus bypassing the deactivation of the second antenna circuit, the resonant tag label 10 remains in a live status when encountering the multiple frequency field at the exit. In this situation, a frequency response is induced by the remaining active antenna circuit (step 310), and a subsequent indication of an alarm condition is provided (step 312).
In the case where the item 22 with the resonant tag label 10 is provided to an uncontrolled retail distributor, it follows that there would be no deactivation of the antenna circuits, thus leaving the resonant tag label in a disabled status (step 314). It follows that upon removal of the item from the uncontrolled retailer, the resonant tag label 10 remains in a disabled status due to neither antenna circuit being deactivated (step 316). However, upon the item being innocently brought within a monitored area at a controlled retailer, the resonant tag label as such precludes triggering of a false alarm condition due to the disabled status of the resonant tag label (steps 318, 320). Accordingly, the system as described accommodates the application of resonant tag labels to items at the packaging source which are rendered into a live status only by deactivation of one of the antenna circuits.
It will be appreciated by those of skill in the art that modifications to the operational sequence of the invention are possible. For instance, the system may be rendered operable for resonant tag labels which include more than two antenna circuits, and which provide indications of an alarm condition in response to receiving predetermined combinations of frequency responses from the active antenna circuits associated with the resonant tag label.
An alternative embodiment of the resonant tag label 10 used in the system 20 is illustrated in Fig. 4, wherein a first antenna pattern 46 which is applied to the surface 44 of a carrier film 42. It will be appreciated that the base layer may include a dielectric coating by itself or in conjunction with the carrier film.
Subsequent layers including a first dielectric coating 48 with through-hole 49 and a conductive plate 50 are applied to the first antenna pattern 46 to form a first tuned antenna circuit 52 with a first predetermined frequency. Thereafter, consecutive layers of a second dielectric coating 54 with through-hole 55 and a second antenna pattern 56 are applied onto the conductive plate 50 to form a second tuned antenna circuit 58 with a second predetermined frequency. Accordingly, the resonant tag label 40 is operational with respect to two different frequencies. As a further aspect of this embodiment, additional alternate layers of conductive plates and antenna patterns with a dielectric coating therebetween may be applied to the label structure, thus rendering the resonant tag label operational with respect to a plurality of frequencies.
The foregoing description has been set forth to illustrate the invention and is not intended to be limited. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the scope of the invention should be limited solely with reference to the appended claims and the equivalents thereof.

Claims

A security system for detecting unauthorized removal of items at an exit from a control area, said system comprising: labels applied to said items, said labels including a plurality of circuit elements, each circuit element being responsive to a different frequency; first deactivating means for modifying said labels from an initial condition in which all of said circuit elements are actively responsive to their respective frequencies, to a live condition in which at least one but not all of said circuit elements is deactivated and rendered non-responsive to its respective frequency; second deactivatinq means for modifying said labels from said live condition to a dormant condition in which at least one additional circuit element is deactivated and rendered non responsive to its respective frequency; frequency generating means at said exit for generating the different frequencies to which said plurality of circuit elements are responsive so as to induce frequency responses by the circuit elements which remain activated; and control means responsive to the frequency responses generated by labels in said live condition for generating a control signal.
The system of claim 1, wherein each of said labels comprises first and second circuit elements.
The system of claim 2, wherein each of said labels comprise a single label component for supporting said first and second circuit elements.
The system of claim 2, wherein each of said labels comprise separate label components for supporting said first and second circuit elements.
The system of claim 2, wherein said first and second circuit elements comprise distinct antenna circuits.
The system of claim 2, wherein said first and second circuit elements comprise a single antenna circuit, said second circuit element being formed by deactivating a predetermined portion of said single antenna circuit.
The system of claim 1, wherein said circuit elements comprise multi-layered antenna circuits.
The system of claim 7, wherein said multi-layered antenna circuits each comprise a plurality of coating layers.
The system of claim 1 further comprising an alarm unit which generates an alarm signal in response to receiving said control signal.
A method of detecting unauthorized removal of items at an exit from a control area, said method comprising the steps of: applying labels to said items, said labels including a plurality of circuit elements, each circuit element being responsive to a different frequency; modifying said labels from an initial condition in which all of said circuit elements are actively responsive to their respective frequencies, to a live condition in which at least one but not all of said circuit elements is deactivated and rendered non-responsive to its respective frequency; modifying said labels from said live condition to a dormant condition in which at least one additional circuit element is deactivated and rendered non-responsive to its respective frequency; generating the different frequencies at said exit to which said plurality of circuit elements are responsive so as to induce frequency responses by the circuit elements which remain activated; and generating a control signal in response to the frequency responses generated by labels in said live condition.
A resonant tag label detection system comprising: a label structure adapted for application to an object; a first circuit element associated with said label structure, said first circuit element being responsive to a predetermined first frequency; a second circuit element associated with said label structure, said second circuit element being responsive to a predetermined second frequency; a frequency generation source for generating said first and second frequencies so as to induce frequency responses by said first and second circuit elements; a receiver unit for receiving said frequency responses induced by said first and second circuit elements; and a control unit which generates a control signal in response to said receiver unit receiving a frequency response from only one of said first and second circuit elements.
The system of claim 11, wherein said label structure comprises a single label component for supporting said first and second circuit elements.
The system of claim 11, wherein said label structure comprises separate components for supporting said first and second circuit elements.
The system of claim 11, wherein said control unit does not generate said control signal in response to said receiver unit receiving no frequency response from said first and second circuit elements or receiving frequency responses from both said first and second circuit elements.
The system of claim 11, wherein said first and second circuit elements comprise multi-layered antenna circuit.
The system of claim 15, wherein said multi-layered antenna circuits each comprise a plurality of coating layers.
The system of claim 11, wherein said first and second circuit elements are initially configured to be active with respect to frequency responses to said predetermined first and second frequencies.
The system of claim 17 further comprising a deactivation unit for deactivating either or both of said first and second circuit elements.
The system of claim 11 further comprising an alarm unit which generates an alarm signal in response to receiving said control signal.
The system of claim 11, wherein said first and second circuit elements comprise distinct antenna circuits.
The system of claim 11, wherein said first and second circuit elements comprise a single antenna circuit, said second circuit element being formed by deactivating a predetermined portion of said single antenna circuit.
A method of detecting an object having a resonant tag label applied thereto, said method comprising the steps of: providing first and second circuit elements associated with said resonant tag label; selectively deactivating said first and second circuit elements; producing predetermined first and second frequencies from a source to said resonant tag label; inducing a first frequency response by said first circuit element in response to being in an active state and receiving said first frequency; inducing a second frequency response by said second circuit element in response to being in an active state and receiving said second frequency; and generating a control signal in response to the inducement of only one of said first and second frequency responses.
The method of claim 22 further comprising the step of generating an alarm signal in response to said control signal being generated.
The method of claim 22, wherein said resonant tag label comprises a single support structure for supporting said first and second circuit elements.
The method of claim 22, wherein said tag resonant label comprises separate structure elements for supporting said first and second circuit elements.
The method of claim 22, wherein said control signal is not generated in response to said no frequency response being induced from said first and second circuit elements or both frequency responses are induced from said first and second circuit elements.
The method of claim 22, wherein said first and second circuit elements comprise multi-layered antenna circuits.
The system of claim 27, wherein said multi-layered antenna circuits each comprise a plurality of coating layers.
The system of claim 22, wherein said first and second circuit elements are initially configured to be active with respect to frequency responses to said predetermined first and second frequencies.
The method of claim 22, wherein said first and second circuit elements comprise distinct antenna circuits.
The method of claim 22, wherein said first and second circuit elements comprise a single antenna circuit, said second circuit element being formed by deactivating a predetermined portion of said single antenna circuit.