Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2001-03-29
2004-04-13
La, Anh V (Department: 2636)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S572600
Reexamination Certificate
active
06720877
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to markers and labels for electronic article surveillance (EAS) systems, and more particularly to manufacturing methods for magnetomechanical and magnetoacoustic EAS markers and labels using RF molding and deposition.
2. Description of the Related Art
U.S. Pat. No. 4,510,489, the '489 patent, discloses an EAS marker made of an elongated strip of magnetostrictive ferromagnetic material disposed adjacent to a ferromagnetic element that, when magnetized, magnetically biases the strip and arms it to resonate mechanically at a preselected resonant frequency. The marker resonates when subjected to an interrogation field at a frequency at or near the marker's resonant frequency. The response of the marker at the marker's resonant frequency can be detected by EAS receiving equipment, thus providing an electronic marker for use in EAS systems. As used herein, the term “marker” refers to, and is used interchangeably with, markers, labels, and tags used to trigger EAS systems.
The marker of the '489 patent is constructed of a resonator, an elongated ductile strip of magnetostrictive ferromagnetic material disposed adjacent a ferromagnetic element. The ferromagnetic element is a high coercivity biasing magnet that, when magnetized, is capable of applying a DC magnetic bias field to the resonator. The resonator is placed within a hollow recess or cavity of the marker housing with the bias held in an adjacent plane parallel to the resonator so that the bias does not cause mechanical interference with the vibration of the resonator. Because the resonator must vibrate freely within its cavity and the bias is maintained in a parallel adjacent plane, the marker has a required minimum thickness to accommodate the adjacent parallel planes and permit free vibration of the resonator.
Presently, the EAS markers described above are manufactured using a vacuum thermal forming process. Referring to
FIG. 1
, the resonator cavity
2
is formed from a flat planar plastic material
3
, and results in a flange
4
extending around the cavity perimeter to which the lid material
5
is thermo-sealed. The lid
5
tends to sag toward the cavity
2
, and the label
1
has a tendency to bow due to shrinkage in the polymer laminates
6
during the thermo-sealing process effectively reducing the depth of the cavity
2
. The resonator cavity
2
must be made deeper to compensate for this cavity depth reduction to permit mechanical freedom for the resonator
7
. Since the thermo-formed cavity
2
essentially rises out of the plane of its flanges
4
, it can be crushed by applied pressure such as by stacking merchandise or vandalism. Crushing the resonator cavity
2
prevents the resonator
7
from freely moving when resonating. The quality of the cavity formation can be improved.
In addition, there are EAS marker applications in which a flat marker is desired. A flat EAS marker is defined herein as an EAS marker of lower minimum thickness than is required to accommodate a bias and a resonator that are maintained in stacked parallel adjacent planes as described above. A flat marker can provide a larger surface area for the attachment of indicia, and may be more bendable. U.S. patent application Ser. No. 09/584,559, the '559 application, assigned to Sensormatic Electronics Corporation, discloses a “side-by-side” bias configuration that results in flat magnetomechanical EAS marker. The disclosure of the '559 application is incorporated herein by reference in its entirety. The '559 application includes disclosure of manufacturing methods for flat EAS markers. Improved manufacturing methods are desired.
BRIEF SUMMARY OF THE INVENTION
A first aspect of the invention is a method of making a magnetomechanical electronic article surveillance marker that includes deposition of at least one elongated bias magnet onto a substrate, depositing a cavity layer onto the substrate where the cavity layer defines an elongated cavity adjacent the bias magnet. Placing a magnetomechanical resonator into the cavity and sealing a cover onto the cavity layer wherein the resonator is captured in the cavity and free to mechanically vibrate substantially unencumbered.
Further, two elongated bias magnets can be deposited on the substrate layer in parallel relation to each other, the elongated cavity can be defined between the two elongated bias magnets. A resonator support member can be deposited in the cavity that rests against a mechanical vibration nodal point of the resonator when the resonator is disposed in the cavity to support the resonator without substantially encumbering mechanical vibration thereof. The elongated bias magnet and the cavity layer can be deposited on opposite sides of the substrate. A first portion of the cavity layer can be deposited on the substrate and a second portion of the cavity layer can be deposited on the cover where sealing connects the first and second cavity layer portions together defining the cavity so the cavity is substantially impervious to restricting the resonator. An adhesive layer can be deposited on the cavity layer prior to sealing a cover onto the cavity layer.
A second aspect of the invention is a method of making a magnetomechanical electronic article surveillance marker that includes placing at least one elongated bias magnet on a substrate layer, depositing a cavity layer on the substrate that covers and attaches the bias magnet to the substrate and defines an elongated cavity adjacent the bias magnet. Placing a magnetomechanical resonator in the cavity and sealing a cover onto the cavity layer where the resonator is captured in the cavity and free to mechanically vibrate unencumbered.
Further, two elongated bias magnets can be placed on the substrate layer in parallel relation to each other with the elongated cavity defined between the two elongated bias magnets. A resonator support member can be deposited in the cavity to rest against a mechanical vibration nodal point of the resonator when the resonator is disposed in the cavity thereby supporting the resonator without substantially encumbering mechanical vibration thereof. A first portion of the cavity layer is deposited on the substrate and a second portion of said cavity layer is deposited on the cover where sealing connects the first and second cavity layer portions together defining the cavity where the cavity is substantially impervious to restricting the resonator. An adhesive layer can be deposited on the cavity layer prior to sealing a cover onto the cavity layer.
A third aspect of the invention is a method of making a magnetomechanical electronic article surveillance marker that includes depositing a cavity layer on a magnetizable substrate layer, the cavity layer defining an elongated cavity. A resonator support member can be deposited in the cavity. Placing a magnetomechanical resonator in the cavity, the resonator support member being disposed between the resonator and the magnetizable substrate layer, and sealing a cover onto the cavity layer wherein the resonator is captured in the cavity and free to mechanically vibrate unencumbered.
Further, the resonator support member is adapted to rest against a mechanical vibration nodal point of the magnetomechanical resonator when the resonator is disposed in the cavity thereby supporting the resonator without substantially encumbering mechanical vibration thereof.
A fourth aspect of the invention is a method of making a magnetomechanical electronic article surveillance marker including molding a cavity in a plastic substrate, the cavity sized to receive a magnetomechanical resonator, the substrate sized relatively slightly larger than the magnetomechanical resonator. Placing the magnetomechanical resonator into the cavity and sealing a first cover layer to the plastic substrate wherein the resonator is captured in the cavity and free to m
Hansen Norm
Lian Ming-Ren
Morgado Eugenio
Patterson Hubert A.
Simone Robert
La Anh V
Sensormatic Electronics Corporation
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