CROSS REFERENCES TO RELATED APPLICATIONS

Not Applicable

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic diagram of the resonant circuit used in the present invention.

FIG. 2 is a schematic diagram of one embodiment of the present invention.

FIG. 3 is a top plan view of one embodiment of the present invention.

FIG. 4 is a bottom plan view of that shown in FIG. 3.

FIG. 5 is a schematic diagram of an alternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the basic resonant circuit associated with the present invention includes capacitor C1 and inductor L1. A conductor coil on one or more layers of a multi-layered EAS label typically forms inductor L1. Two conductive plates separated by a dielectric material form capacitor C1.

Referring to FIG. 2, inductor L1 is connected to conductive capacitor plates 2 and 4 as shown in the illustration of the relevant portions of an RF EAS tag 1, according to one embodiment of the present invention. Capacitor plates 2 and 4 of capacitor C1 are separated by dielectric material 6. Dielectric material 6 can be an adhesive layer that retains plates 2 and 4 in their desired position. Inlaid in a cutout or void area of dielectric material 6 is a matrix made of a conductive material in a nonconductive binder 8. The conductive material can be any suitable conductive material that is adapted to be mixed with a binder, and can include, but is not limited to, a metal such as copper, aluminum, bronze, and the like, or a conductive material such as carbon. The nonconductive binder can be made of, but is not limited to, varnish, polymers, polyurethane, and other nonconductive materials, the selection of which is well known in the art. Upon exposure to an electromagnetic field of sufficient magnitude and at the appropriate frequency and duration, the matrix of conductive material and nonconductive binder 8 forms a carbonized or conductive path between capacitor plates 2 and 4. The carbonized path shorts plates 2 and 4 of capacitor C1 rendering the EAS tag 1 non-resonant at its operating frequency, or deactivated. The field level required to resonate tag 1 for normal operation is lower than the magnitude required to short capacitor C1. Normal operation means that when tag 1 resonates it produces a signal detectable by an electronic article surveillance receiver (not shown). Deactivation occurs only when tag 1 is radiated with a field level of sufficient magnitude required for deactivation, which shorts plates 2 and 4.

Referring to FIG. 3, a top plan view of one embodiment of the present invention shows inductor L1 may be formed by a coil of copper or other suitable conductor material on adhesive dielectric material 6, which also carries conductor plate 2 of capacitor C1. Additional layers may be present, but are not shown. Inductor L1 is connected to through contact 9.

Referring to FIG. 4, a bottom plan view of the embodiment illustrated in FIG. 3 shows through contact 9 in electrical connection with conductor plate 4 of capacitor C1. The electrical circuit is thus completed as illustrated in FIG. 1. As stated, additional layers may be present, as well as other physical implementations of coil L1 and capacitor plates 2 and 4.

Referring to FIG. 5, the relevant portions of an alternate embodiment of RF EAS tag 10 is illustrated. In tag 10, conductive capacitor plates 12 and 14 are both separated from dielectric material 6 by an oxide layer 16. A conductive material 18, which can be a conductive material as described hereinabove or another conductive material, is inlaid in an opening or void area in dielectric material 6. Exposing tag 1 to an electromagnetic field of sufficient magnitude, frequency, and duration causes a carbonizing path through oxide layer 16 between the conductive plates 12 and 14 and conductive material 18. The resulting short circuit of capacitor C1 renders tag 10 non-resonating at the intended operating frequency, and deactivates tag 10.

In the present invention, one resonant frequency selection is about 8 MHz, but the invention is not so limited and can be used at other frequencies. The desired deactivation electromagnetic field can be a similar RF field but of relatively high magnitude, and can be an RF pulse. The invention can be implemented at other frequencies as long as a suitable shorting deactivation mechanism can be implemented by an electrically weakened area as disclosed herein.

It is to be understood that variations and modifications of the present invention can be made without departing from the scope of the invention. It is also to be understood that the scope of the invention is not to be interpreted as limited to the specific embodiments disclosed herein, but only in accordance with the appended claims when read in light of the forgoing disclosure.