CA1245321A - Method, system and apparatus for use in article surveillance - Google Patents
Method, system and apparatus for use in article surveillanceInfo
- Publication number
- CA1245321A CA1245321A CA000496093A CA496093A CA1245321A CA 1245321 A CA1245321 A CA 1245321A CA 000496093 A CA000496093 A CA 000496093A CA 496093 A CA496093 A CA 496093A CA 1245321 A CA1245321 A CA 1245321A
- Authority
- CA
- Canada
- Prior art keywords
- marker
- magnetic
- component
- field
- ribbon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
- G08B13/24—Electrical actuation by interference with electromagnetic field distribution
- G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
- G08B13/2405—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting characterised by the tag technology used
- G08B13/2408—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting characterised by the tag technology used using ferromagnetic tags
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
- G08B13/24—Electrical actuation by interference with electromagnetic field distribution
- G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
- G08B13/2428—Tag details
- G08B13/2437—Tag layered structure, processes for making layered tags
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
- G08B13/24—Electrical actuation by interference with electromagnetic field distribution
- G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
- G08B13/2428—Tag details
- G08B13/2437—Tag layered structure, processes for making layered tags
- G08B13/244—Tag manufacturing, e.g. continuous manufacturing processes
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
- G08B13/24—Electrical actuation by interference with electromagnetic field distribution
- G08B13/2402—Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting
- G08B13/2428—Tag details
- G08B13/2437—Tag layered structure, processes for making layered tags
- G08B13/2442—Tag materials and material properties thereof, e.g. magnetic material details
Abstract
Abstract of the Disclosure There is described an electronic surveillance system marker which may include a unitary active component responsive to incident magnetic energy for causing an associated article surveillance system to render an output alarm. The marker is adapted to be deactivated through change in the molecular organization of the active component without requiring disruption of the component, or change in its chemical composition. There is also described a method which provides for the deactivating of an article surveillance marker, which method includes the step of modifying the molecular organization of the active component of the marker.
Description
~LZ~ 53Zl C4-069/076 Application of Floyd B. Humphrey METHOD, SYSTEM AND APPARATUS FOR USE IN ARTICLE SURVEILLANCE
FIELD OF THE INVENTION , The present invention relates broadly to article surveillance and more particularly to article surveillance systems generally referred to as of the magnetic type and to methods and apparatus therefor.
BACKGROUND OF THE INVENTION
Common to prior art magnetic type article surveillance systems is the detection of perturbations induced in an incident magnetic field by an article marker in the course of reversal of magnetic polarity of the field. Typically, such prior art systems include a magnetic field generator, operative to establish an alternating magentic field in an area of interes~, i.e., a surveillance control zone, and a receiver operative to detect perturbations in the magnetic field which may be induced, speclfically those of such markers.
When the marker magnetic material is driven around its hysteresis loop, from one polarity to the opposite, as occurs upon its exposure to the alternating magnetic field, a signal pulse is produced by the receiver. The shape of this pulse is a function of the time it takes to reverse polarity, i.e., proceed ~, ~
.:
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from one saturation point to the other, or from a residual induction point to the reverse saturation point. This time element, in prior art systems, is a function of the time rate of change of the incident field between levels sufficient to effect such polarity reversal. , The primary prior art effort has been directed to the finding of marker magnetic materials with higher and higher permeability and lower and lower coercivity, thereby-to give rise to increased slope of the ~ransition from one polarity to the other, otherwise stated,lesser time for the transition.
Since the generation of higher order harmonics of sufficient amplitude to be readily detectable attends such increased slope, enhanced discrimination as against perturbations induced in the magnetic field by commonplace objects in the surveillance control zone is thereby attainable. With the same purpose in view, prior art systems have looked to operation at relatively high fre~uencies and/or with strong incident fields, and the latter is generally sought by establishing narrow surveillance control zones to limit the distance from marker to antenna.
In applicant's view, these efforts have not yielded magnetic markers which produce article tags which, in.response to a surveillance field interrogation, provide a signal su~ficiently uni~ue that the marker is free from being mimicked by at least some commonplace article. For example, certain samples of nickel plating have been observed to produce signals,
FIELD OF THE INVENTION , The present invention relates broadly to article surveillance and more particularly to article surveillance systems generally referred to as of the magnetic type and to methods and apparatus therefor.
BACKGROUND OF THE INVENTION
Common to prior art magnetic type article surveillance systems is the detection of perturbations induced in an incident magnetic field by an article marker in the course of reversal of magnetic polarity of the field. Typically, such prior art systems include a magnetic field generator, operative to establish an alternating magentic field in an area of interes~, i.e., a surveillance control zone, and a receiver operative to detect perturbations in the magnetic field which may be induced, speclfically those of such markers.
When the marker magnetic material is driven around its hysteresis loop, from one polarity to the opposite, as occurs upon its exposure to the alternating magnetic field, a signal pulse is produced by the receiver. The shape of this pulse is a function of the time it takes to reverse polarity, i.e., proceed ~, ~
.:
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from one saturation point to the other, or from a residual induction point to the reverse saturation point. This time element, in prior art systems, is a function of the time rate of change of the incident field between levels sufficient to effect such polarity reversal. , The primary prior art effort has been directed to the finding of marker magnetic materials with higher and higher permeability and lower and lower coercivity, thereby-to give rise to increased slope of the ~ransition from one polarity to the other, otherwise stated,lesser time for the transition.
Since the generation of higher order harmonics of sufficient amplitude to be readily detectable attends such increased slope, enhanced discrimination as against perturbations induced in the magnetic field by commonplace objects in the surveillance control zone is thereby attainable. With the same purpose in view, prior art systems have looked to operation at relatively high fre~uencies and/or with strong incident fields, and the latter is generally sought by establishing narrow surveillance control zones to limit the distance from marker to antenna.
In applicant's view, these efforts have not yielded magnetic markers which produce article tags which, in.response to a surveillance field interrogation, provide a signal su~ficiently uni~ue that the marker is free from being mimicked by at least some commonplace article. For example, certain samples of nickel plating have been observed to produce signals,
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responsively to such magnetic fields, that cause false alarms in sys~ems intended to selectively respond to markers containing Permalloy as their magnetic matter.
In one prior art magnetic type system, deactivation of a magnetic marker is effected by the inclusio~ in a marker of first and second separate and distinct components of diverse magnetic material, the first serving to generate the detectable signal, and the second serving, upon the occurrence of certain marker deactivating events, to mask and render inoperative the first component. Such masking takes place at a deactivation station and is effected by subjecting the composite marker to a magnetic field of such strength as to activate the second component.
Typically, the marker is subject to a magnetic field adapted to provide output indication of an alarm condition upon presence of the marker in the surveillance zone on the basis of magnetic polarity reversal of the first marker component. On the other hand, upon the presence of the article with marker in an authorized checkout area preceding the surveillance zone, one can deactivate the marker by disposing the same in a magnetic field of character activating the second component that in turn changes the magnetic response of the first marker component.
Another prior approach to marker deactivation involves the formation, in a resonant frequency marker printed circuit, of a fusible link, i.e., a portion of lessened cross-section than the
responsively to such magnetic fields, that cause false alarms in sys~ems intended to selectively respond to markers containing Permalloy as their magnetic matter.
In one prior art magnetic type system, deactivation of a magnetic marker is effected by the inclusio~ in a marker of first and second separate and distinct components of diverse magnetic material, the first serving to generate the detectable signal, and the second serving, upon the occurrence of certain marker deactivating events, to mask and render inoperative the first component. Such masking takes place at a deactivation station and is effected by subjecting the composite marker to a magnetic field of such strength as to activate the second component.
Typically, the marker is subject to a magnetic field adapted to provide output indication of an alarm condition upon presence of the marker in the surveillance zone on the basis of magnetic polarity reversal of the first marker component. On the other hand, upon the presence of the article with marker in an authorized checkout area preceding the surveillance zone, one can deactivate the marker by disposing the same in a magnetic field of character activating the second component that in turn changes the magnetic response of the first marker component.
Another prior approach to marker deactivation involves the formation, in a resonant frequency marker printed circuit, of a fusible link, i.e., a portion of lessened cross-section than the
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remaining marker printed circuitry, and the disrupting of the link by exposing the marker to increased field energy sufficient to disrupt the integrity of the link. Whereas the marker was of resonant frequency for alarm ac-tivation prior to the link dis-ruption, it becomes otherwise upon that event, and passes freely through the surveillance control zone.
The deactivation schemes of the referenced prior art have evident disadvantage, the former in its requirement for plural separate components, respectively for activation and deactivation of the marker, and the latter in its requirement for fusible link formation in the marker printed circuit.
According to the present invention there is providèd a marker for use in an article surveillance system in which an alternating magnetic field is established in a surveillance region and an alarm is activated when a predetermined perturba-tion to the field is detected, the marker comprising a body of magnetic with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that exposure of the body to an external magnetic field, whose field strength in the direction opposing the magnetic polariæation of the body exceeds a predetermined threshold value, results in regenerative reversal of the magnetic polarization, and means Eor securing the body to an article to be maintained under surveillance.
The invention also provides for deactivating an article surveillance marker such as of type having an active component responsive to incident magnetic energy for causing an associated article surveillance system to render an output alarm, the " l2L~cj3zl method including a step of modifying the molecular organization of the active component.
In a further aspect, the invention provides an electronic article surveillance system operative with an article marker such as of type comprising a component responsive to incident magnetic energy for causing an associated article surveillance system to render an output alarm, the marker being adapted to be deactivated through change in the molecular organization of its active component, such system comprising transmitting means for establishing an alternating magnetic field of intensity in excess of a predetermined threshold value in a control zone of interest, receiving means for detection in said control zone of the presence of such marker iE same is not deactivated.
Means may be provided for deactivating such marker through such molecular organizational change.
Turning more particularly to the preferred products, methods and systems of the invention, the marker active component is selected to be of molecularly unorganized, e.g., amorphous matter, provided such as by ~netal wire obtained directly from the rapid quench of molten metal and having dimensions below discussed.
In one product aspect, the marker is used in such unannealed state as a surveillance device. The deactivation step involves mole-cularly organizing such matter, e.g., by rendering crystalline at least a portion of the component. Such deactivation step is desirably practiced by maintaining such portion of the marker component at a temperature above the crystallization temperature of the component and thereby to crystallize a coercive force in that portion different from its previous coercive force.
~ Z~5~Zi In a preferred embodiment, the marker deactivating means of systems of the invention modifies the molecular organi-zation of the marker component by including an electric current supply for selective electrical connection to at least a portion of the marker component and providing such current level therein as to maintain the portion of the marker component, thereby to crystallize such coercive force in the portion different from its previous coercive force. Radiant energy may also be employed in this deactivating practice.
Alternatively, the marker actlve component has stress mechanically induced therein, as by annealing wire in twisted state and constraining same in untwisted form following cooling.
Stress-relieving deactivation here involves the relieving of such retained mechanical stress, as by releasing the constraint on the active component. In this instance, the deactivating means may impart mechanical force or radiant energy to the marker component.
The following is a description by way of example of certain embodiments of the invention and practices thereof, reference being had to the accompanying drawings wherein like reference numerals identify like parts throughout:
~ Z~532~
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspectlve view with portlons broken away of a typical prior art magnetic marker;
Fig. 2 is a typical hysteresis curve illustrative of the magnetic characteristics of the marker of Fig. 1, Fig. 3 is a view similar to Fig. 1, but showing a marker for deactivation in accordance with the present invention;
Fig. 4 is a hysteresis curve illustrative of the--magnetic characteristics of the marker of Fig~ 3i Fig. 5 is a perspective view of a ribbon of magnetic material that has been specially processed to produce at least one Barkhausen discontinuity in its hysteresis loop and which represents another product embodiment for deactivation in accordance with the present invention;
Fig. 6 ls a series of four curves showing the pulse response to external excitation as obtained from a marker such as that of Fig. 1, when constructed of permallo~, in response to four different levels of field excitation;
Fig. 7 is a series of four curves, similar to those of Fig.
6, but for the marker of Fig. 1 when constructed of "Metglas"
ductile amorphous metal ribbon;
Fig. 8 is a series of four curves, similar to those of Fig.
6, showing for purpose of comparison the response of a marker in accordance with the invention to the same our levels of field excitation;
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Fig. 9 is a block diagram of the test equipment utilized to produce the curves of Figs. 6, 7, 8 and 14, as well as the spectrograms of Figs. 10, 11 and 12;
Fig. 10 is a series of four spectrograms presenting the frequency content of the signal obtained from a prior art marker exposed to an incident field at 60 hertz and field strengths of 0.6, 1.2, 2.4 and 4.5 oersteds;
Fig. 11 is a series of four spectrograms showing-the frequency content of the signal obtained from the markers of the invention when exposed to the same levels of excitation as in Fig. 10;
Fig. 12 is similar to Fig. 10, but showing the response of a 'IMetglas'' ribbon to the same four excitation levels;
Fig. 13 is a block diagram of a typical system for establishing a surveillance field and detecting the markers of the invention;
Fig. 14 is a series of three curves showing and comparing the pulse response to an external excitation, at a frequency of 20 Hz and a level of 1.2 oersteds, of the permalloy, "Metglas", and invention markers whose response at 60 Hz is shown in Figs.
6, 7 and 8;
Fig. 15 is a block diagram of a typical electronic article surveillance system in accordance with the invention;
Fig. 16 is a schematic diagram of a first embodiment of the deactivating unit of the Fig. 15 system shown with a marker ,~ _ .
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thereof;
Fig. 17 is a schematic diagram of a second embodiment of the deactivation unit of the Fig. 15 system again shown with a marker thereof; and Fig. 18 illustrates a third embodiment of the deactivation unit of the Fig. 15 system for use with markers having stress induced magnetic discontinuities.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS AND PRACTICES
Referring now to Fig. 1, a typical prior art marker designated generally by the reference numeral 10, is shown as consisting of a substrate 11 and an overlayer 12 between which is sandwiched and concealed a length of ribbon 13 of high permeability magnetic material. The undersurface of the substrate 11 can be coated with a suitable pressure sensitve adhesive for securing the marker to an article to be maintained under surveillance. Alternatively, any other known arrangement can be employed to secure the marker to the article. In this particular example, which was used to obtain the reference test data to be discussed below, the ribbon 13 was formed from 4-79 Molybdenum Permalloy 0.100" wide, 0.001"thick, and 3.0" long.
It had a coercivity, Hc, of 0.05 oersteds, and permeability at 100 Hz of 45,000 to 55,000.
The hysteresis loop or cuxve of the ribbon 13 is shown in rather general terms in Fig. 2. No attempt has been made to _ ~ _ ".. . ..
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draw the loop to any type of scale or in scale proportions for such curve would appear very tall along the B axis and very narrow along the H axis. Wh~at is significant is that the curve between the knee at 14 and positive saturation at 15, as well as from the knee 16 down to the negative satur~tion point at 17, has a finite slope less than infinite. In ordex to reverse the magnetic polarity of the ribbon 13 it is necessary to subject it to an external field of at least Hm to bring the material to at least its maximum induction point 18. The speed with which this can be accomplished is a direct function of the rate of change of the incident magnetic field, and the rate of change is proportional to both the frequency and the peak amplitude of such incident field.
In order to illustrate this effect, the sample described with reference to Fig. 1 was subjected to a 60 Hz field of selectable intensity, and a curve tracer was employed to obtain a plot of the pulse thereby~produced when thP ribbon 13 reversed polarity. Fig. 6A shows the wave shape in response to a 1.2 oersteds field, while Figs. 6B, 6C and 6D show the effect of increasing the field stxen~th, respectively, to 204, 3.4, and
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remaining marker printed circuitry, and the disrupting of the link by exposing the marker to increased field energy sufficient to disrupt the integrity of the link. Whereas the marker was of resonant frequency for alarm ac-tivation prior to the link dis-ruption, it becomes otherwise upon that event, and passes freely through the surveillance control zone.
The deactivation schemes of the referenced prior art have evident disadvantage, the former in its requirement for plural separate components, respectively for activation and deactivation of the marker, and the latter in its requirement for fusible link formation in the marker printed circuit.
According to the present invention there is providèd a marker for use in an article surveillance system in which an alternating magnetic field is established in a surveillance region and an alarm is activated when a predetermined perturba-tion to the field is detected, the marker comprising a body of magnetic with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that exposure of the body to an external magnetic field, whose field strength in the direction opposing the magnetic polariæation of the body exceeds a predetermined threshold value, results in regenerative reversal of the magnetic polarization, and means Eor securing the body to an article to be maintained under surveillance.
The invention also provides for deactivating an article surveillance marker such as of type having an active component responsive to incident magnetic energy for causing an associated article surveillance system to render an output alarm, the " l2L~cj3zl method including a step of modifying the molecular organization of the active component.
In a further aspect, the invention provides an electronic article surveillance system operative with an article marker such as of type comprising a component responsive to incident magnetic energy for causing an associated article surveillance system to render an output alarm, the marker being adapted to be deactivated through change in the molecular organization of its active component, such system comprising transmitting means for establishing an alternating magnetic field of intensity in excess of a predetermined threshold value in a control zone of interest, receiving means for detection in said control zone of the presence of such marker iE same is not deactivated.
Means may be provided for deactivating such marker through such molecular organizational change.
Turning more particularly to the preferred products, methods and systems of the invention, the marker active component is selected to be of molecularly unorganized, e.g., amorphous matter, provided such as by ~netal wire obtained directly from the rapid quench of molten metal and having dimensions below discussed.
In one product aspect, the marker is used in such unannealed state as a surveillance device. The deactivation step involves mole-cularly organizing such matter, e.g., by rendering crystalline at least a portion of the component. Such deactivation step is desirably practiced by maintaining such portion of the marker component at a temperature above the crystallization temperature of the component and thereby to crystallize a coercive force in that portion different from its previous coercive force.
~ Z~5~Zi In a preferred embodiment, the marker deactivating means of systems of the invention modifies the molecular organi-zation of the marker component by including an electric current supply for selective electrical connection to at least a portion of the marker component and providing such current level therein as to maintain the portion of the marker component, thereby to crystallize such coercive force in the portion different from its previous coercive force. Radiant energy may also be employed in this deactivating practice.
Alternatively, the marker actlve component has stress mechanically induced therein, as by annealing wire in twisted state and constraining same in untwisted form following cooling.
Stress-relieving deactivation here involves the relieving of such retained mechanical stress, as by releasing the constraint on the active component. In this instance, the deactivating means may impart mechanical force or radiant energy to the marker component.
The following is a description by way of example of certain embodiments of the invention and practices thereof, reference being had to the accompanying drawings wherein like reference numerals identify like parts throughout:
~ Z~532~
DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspectlve view with portlons broken away of a typical prior art magnetic marker;
Fig. 2 is a typical hysteresis curve illustrative of the magnetic characteristics of the marker of Fig. 1, Fig. 3 is a view similar to Fig. 1, but showing a marker for deactivation in accordance with the present invention;
Fig. 4 is a hysteresis curve illustrative of the--magnetic characteristics of the marker of Fig~ 3i Fig. 5 is a perspective view of a ribbon of magnetic material that has been specially processed to produce at least one Barkhausen discontinuity in its hysteresis loop and which represents another product embodiment for deactivation in accordance with the present invention;
Fig. 6 ls a series of four curves showing the pulse response to external excitation as obtained from a marker such as that of Fig. 1, when constructed of permallo~, in response to four different levels of field excitation;
Fig. 7 is a series of four curves, similar to those of Fig.
6, but for the marker of Fig. 1 when constructed of "Metglas"
ductile amorphous metal ribbon;
Fig. 8 is a series of four curves, similar to those of Fig.
6, showing for purpose of comparison the response of a marker in accordance with the invention to the same our levels of field excitation;
_ ~ _ ~2453,~
Fig. 9 is a block diagram of the test equipment utilized to produce the curves of Figs. 6, 7, 8 and 14, as well as the spectrograms of Figs. 10, 11 and 12;
Fig. 10 is a series of four spectrograms presenting the frequency content of the signal obtained from a prior art marker exposed to an incident field at 60 hertz and field strengths of 0.6, 1.2, 2.4 and 4.5 oersteds;
Fig. 11 is a series of four spectrograms showing-the frequency content of the signal obtained from the markers of the invention when exposed to the same levels of excitation as in Fig. 10;
Fig. 12 is similar to Fig. 10, but showing the response of a 'IMetglas'' ribbon to the same four excitation levels;
Fig. 13 is a block diagram of a typical system for establishing a surveillance field and detecting the markers of the invention;
Fig. 14 is a series of three curves showing and comparing the pulse response to an external excitation, at a frequency of 20 Hz and a level of 1.2 oersteds, of the permalloy, "Metglas", and invention markers whose response at 60 Hz is shown in Figs.
6, 7 and 8;
Fig. 15 is a block diagram of a typical electronic article surveillance system in accordance with the invention;
Fig. 16 is a schematic diagram of a first embodiment of the deactivating unit of the Fig. 15 system shown with a marker ,~ _ .
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thereof;
Fig. 17 is a schematic diagram of a second embodiment of the deactivation unit of the Fig. 15 system again shown with a marker thereof; and Fig. 18 illustrates a third embodiment of the deactivation unit of the Fig. 15 system for use with markers having stress induced magnetic discontinuities.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS AND PRACTICES
Referring now to Fig. 1, a typical prior art marker designated generally by the reference numeral 10, is shown as consisting of a substrate 11 and an overlayer 12 between which is sandwiched and concealed a length of ribbon 13 of high permeability magnetic material. The undersurface of the substrate 11 can be coated with a suitable pressure sensitve adhesive for securing the marker to an article to be maintained under surveillance. Alternatively, any other known arrangement can be employed to secure the marker to the article. In this particular example, which was used to obtain the reference test data to be discussed below, the ribbon 13 was formed from 4-79 Molybdenum Permalloy 0.100" wide, 0.001"thick, and 3.0" long.
It had a coercivity, Hc, of 0.05 oersteds, and permeability at 100 Hz of 45,000 to 55,000.
The hysteresis loop or cuxve of the ribbon 13 is shown in rather general terms in Fig. 2. No attempt has been made to _ ~ _ ".. . ..
~t.53a~
draw the loop to any type of scale or in scale proportions for such curve would appear very tall along the B axis and very narrow along the H axis. Wh~at is significant is that the curve between the knee at 14 and positive saturation at 15, as well as from the knee 16 down to the negative satur~tion point at 17, has a finite slope less than infinite. In ordex to reverse the magnetic polarity of the ribbon 13 it is necessary to subject it to an external field of at least Hm to bring the material to at least its maximum induction point 18. The speed with which this can be accomplished is a direct function of the rate of change of the incident magnetic field, and the rate of change is proportional to both the frequency and the peak amplitude of such incident field.
In order to illustrate this effect, the sample described with reference to Fig. 1 was subjected to a 60 Hz field of selectable intensity, and a curve tracer was employed to obtain a plot of the pulse thereby~produced when thP ribbon 13 reversed polarity. Fig. 6A shows the wave shape in response to a 1.2 oersteds field, while Figs. 6B, 6C and 6D show the effect of increasing the field stxen~th, respectively, to 204, 3.4, and
4.5 oersteds.
In like manner, a ribbon of "Metglas" ductile amorphous metal produced by Allied Corporation of Morris Township, New Jersey, was subjected to the same levels of excitation, also at 60 Hz, and the resulting pulses are plotted in Figs. 7A, 7B, 7C
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and 7D. The "Metglas" ribbon was 0.070" wide, 0.0007" thick, and 3.0" long. It was identified as "Metglas" strip/2826M~2, having a maximum permeability of 180,000, a coercivity, Hc, of 0.035 oersteds, and saturation magnetization of 9,000 Gauss.
Before discussing in further detail the~,wave shapes shown in Figs. 6 and 7 and their implication with regard to an article surveillance system, it will be useful to have an understanding of the present invention and the pulse forms thereby--obtainable~ Referring to Fig. 3, there is shown a marker 20 having a substrate 21 and an overlayer 22 that can be the same as the components 11 and 12, respectively, in Fig. 1, and can be attached to an article in similar fashion. However, instead of the ribbon 13, the active element in the embodiment of Fig. 3 is a length of amorphous metal wire 23. A sample used to provide the test data to be discussed was approximately 7.6 cm t3") long, has a diameter of 0.125 mm, and its composition satisfied the formula Fe81 Si4 B14 Cl, where the percentages are in atomic percent. These parameters should be considered only as representing one example~for the purpose of explanation since, as will appear from the ensuing discussion, the diameter can range between O.O9 and 0.15 mm while the length can range between about 2.5 and 10 cm for use as a surveillance marker.
The demagnetizing factor for the length of wire, 23, preferably does not exceed 0.000125. At present, however, the dimensions of the above sample are preferred for the wire 23.
What has been described so far is not unusual, but the _ ~ _ .. . ~ . ~ . , .
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particular wire used for the element 23 is unique in that it is characterized by a discontinuous hysteresis characteristic. Not by a slight discontinuity, but by a large Barkhausen discontinuity such that when the magnitude of an incident field of appropriate direction relative to the ma~netic polarity of the wire exceeds a low threshold value, in this case substantially less than 1.0 oersted, the magnetic polarity of the wire will reverse regeneratively, independent of--any further increase in the incident field, up to its maximum induction point. The threshold for the above sample is actually less than 0.6 oersted.
The nature of the hysteresis loop is shown in Fig. 4.
Again, the scale and proportions in Fig. 4 are grossly distorted from reality for the sake of convenience in explanation. Thus, the magnetizing field from the negative residual induction point 24 to the threshold point 25 is less than 1.0 oersted. Once the magnetizing field exceeds th~e threshold value for the smaple, there occurs an abrupt regenerative reversal of the polarity, represented by the broken line segment 26 of the hysteresis loop, until the maximum induction point 27 is reached. If the magnetizing field continues to increase above the threshold point, the flux density will increase toward the positive saturation point 28. Otherwise, the element 23 will head toward its positive residual induction point 29 as the magnitude of the magnetizing field approaches zero, and will remain there until ~LZ~532~
the magnetizing field departs from zero. If the magnetizing field now increases in the negative direction, the flux density will follow the stable portion of the loop to the negative threshold point 30 from which it shifts regeneratively and-substantially instantaneously along the broken line segment 31 to the negative maximum induction point 32 and then to a point between saturation at 33 and threshold 25 as a function of the magnetizing field.
It should now be apparent that change in the magnetic polarity of the wire 23 between either points 25 and 27 or 30 and 32 occurs independent of the rate of change of the magnetizing field. All that is important is that the magnetizing field exceed the threshold level of the particular wire element 23. This fact is borne out by the pulse forms obtained from the wire 23 under different Ievels of field excitation which pulse forms are shown in Fig. 8. While there is some difference between the sharpness or time duration of the signal spikes such differences are slight when a comparison is made with Figs. 6 and 7 showing the pulses from prior art marker strips.
The above-mentioned sample of wire 23 was 7.6 cm. long. It has been found that varying the length over the mentioned range will influence the hysteresis loop by chanaing the slope of the portions 28-30 and 33-25, shown in solid lines. As the wire is made shorter, the aforementioned slope will increase, while as 1~
3~
the wire is made longer, the slope in question will decrease.
Changing the aforesaid slope will alter the sharpness of the pulse. Thus, if a longer wire 23 can be tolerated and it is so desired, the differences between the pulses in the various parts of Fig. 8 can be reduced. However, it is ge.nerally the sensitivity and selectivity of the surveillance system in which the marker is to operate that determines what pulse wave shapes can be tolerated and that imposes a limit on the minimum length of wire. The wire 23 must be long enough to produce a pulse with sufficient definition that it can be detected by the detecting system.
While the pulses illustrated in Fig. 7 were from a test sample of amorphous metal, it did not have a Barkhausen discontinuity, and comparison with the pulses in Fig. 8, also from an amorphous metal but with a Barkhausen discontinuity, reveals a profound difference. The significant change in pulse width shown in Fig. 7 and the very close mimicking of the permalloy sample as the excitation is increased from 1.2 to 4.5 oersteds is but an indication that the "Metglas" sample did not have a Barkhausen discontinuity in its hysteresis characteristic. By contrast, Fig. 8 reveals the pxesence of a Barkhausen discontinuity, which is necessary~ at the specified levels and frequency of the exciting ~ield, to give rise to the extremely short duration pulses with comparatively little change in width over the exciting range.
.
_ ~_ .
3~i The invention is not limited to a wire marker. Instead, it encQmpasses any body of magnetic material having a large Barkhausen discontinuity in its hysteresis loop associated with a relatively low switching threshold, preferably no greater than about 1.0 oersted. For example, similar results can be obtained if the same material from which wire 23 was produced is used to producç a ribbon of amorphous metal such as shown in Fig. 5.
The ribbon designated 35 in Fig. 5, can be produced by any known method for rapidly quenching molten metal to avoid crystallization. Starting with a ribbon about 2 mm wide and about .025 mm thick between 3 and 10 cm long, it should be twisted up to 4 turns per 10 cm and annealed while so twisted, the annealing being performed at about 3~0C. for about 25 minutes. When cool, the ribbon should be untwisted and laminated within substrate and over ayer in a flat condition similar to that shown in Fig. 1. The flattened ribbon will have locked in stresses providing a helical easy axis of magnetization and giving rise to the subject discontinuities.
In other words, the ribbon or strip should have stress induced magnetic discontinuity when restrained in flattened condition.
In order to understand the implication o~ using the above described markers, having large hysteresis loop Barkhausen discontinuities, in an article surveillance system, it is helpful to examine the fre~uency spectra of the pulse signals obtained from such markers. For this purpose a testing system ; ~ If 1~53;~:1 was assembled as shown in Fig. 9. An adjustable fre~uency generator or source 40 was connected through an adjustable attenuator 41 to a field generating coil 42. With this arrangement a magnetizing field could be established within a controlled space having a desired ~requency,,and field strength.
By appropriate calibration and metering (not shown) known levels of excitation were obtainable at the position of the marker 43.
Any stimulation of the marker .43 resulting in field perturbation was detected by a suitable field receiving coil 44 whose output was coupled through a receiver'45 to a curve tracer and spectrum analyzer 46. This system was used to produce the curves in Figs. 6, 7, 8 and 14 as well as the spectrograms of Figs. 10 to 12.
Referri~g now to Figs. 10 to 12, they constitute spectrograms of the pulse trains obtained from the prior art markers and a marker according to the invention when such markers were excited by magnetizing fields of fixed frequency ~60 Hz) and various levels of field excitation. The frequency of the harmonic component is plotted along the x-axis while the pea~ amplitude of the harmonic is plotted along the y-axis.
However, the x-axis has a zero offset with the origin corresponding to 60 Hæ, the fundamental fre~uency, so that the ~irst component to the right, designated by the numeral 50 in Fig. lOA, corresponds to the 2nd harmonic at 120 Hz.' A series of dots above a bar line signifies that the amplitude exceeded 1~
,~
. . :
~2~5~Z~
the range covered by the graph.
If Fig. 10 is examined, it reveals how field strength dependent is the output from prior art permalloy strip markers.
The same marker element was used for these spectrograms as was described with re~erence to Fig. 6. Thus, when subjected to 0.6 oersted field excitation the permalloy strip produced a pulse in which the 33rd harmonic was the highest detectable with sufficient amplitude not to be masked by background noise in a surveillance system. At an excitation of 1.2 oersted as shown in Fig. lOB, the 33rd harmonic is still the highest detectable, although there is a stronger presence of the low order harm~nics. The magnitude of the 33rd harmonic, however, has remained essentially the same as at the lower 0.6 oersted excitation. The 63rd harmonic is noticeable at 2.4 oersteds ~Fig. lOC), while at an excitation of 4.5 oersteds (Fig. lOD) the 99th harmonic is beginning to appear.
Now, compare with Fig. ao the corresponding spectrograms for the marker according to the invention as shown in Fig. 11. With the invention, at every level of excitation, from 0.6 oersted on up, harmonics on out as far as the 99th harmonic are present with significant amplitude to be readily detectable. whether the pulse envelopes of Fig. 8 are compared with those of Fig. 6, or the spectrograms of Fig. 11 are compared with those of Fig.
10, the differences are readily perceived. With the invention, a broad band of higher order harmonics appears at a relatively 1~
~2~S3;~1 low level of magnetizing field excitation, an excitation level below that level at which prior art permalloy strips produce any significant detectable output. Consequently, a detection system can be assembled to detect the new marker wlthout interference by permalloy strips or any other similar prior art marker. An example of a system is shown in Fig. 13 wherein a low frequency generator 60 of 60 Hz signal drives a field generating coil 61.
When a marker 20 is in the field from coil 61, its perturbations are received by a field receiving coil 62 whose output is passed through a high pass filter circuit 63 having a suitable cutoff ~requency. Signals passed by filter 63 are supplied to a frequency selection/detection circuit 64. Depending upon the screen provided in circuit 64, when a predetermined pattern of fre~uency, amplitude and/or pulse duration is detected~ the circuit 64 will furnish an output to activate an alarm 65. From a consideration of the graphs of Figs. 10 and 11 it should be evident that the unique markers according to the invention can be detected by systems that can be made immune to permalloy strips. Also, from a consideration of Fig. 11, it should be evident that the response of the invention marker is detectab~e over a wide range of magnetizing field strength.
Referring now to Fig. 12, there is shown the corresponding frequency spectra that was obtained from the "Metglas" ductile amorphous metal sample. At an excitation of 0.6 oersteds the highest order harmonic detectable with any significant amplitude 1~5~Z~
is the 26th. At 1.2 oersteds excitation the 29th harmonic has appeared, while the 33rd harmonic first appears at 2.4 oersted excitation. At the maximum excitation of 4.5 oersteds, the highest noticeable harmonic is the 65th. The overall spectral pattern bears an extremely close resemblanc~ to that shown in Fig. 10 for permalloy, and cannot be mistaken for the drastically different spectrum shown in Fig. 11 for the invention.
The dependency of prior art markers on time rate of change f the incident field has led prior workers in the article surveillance field toward the use of higher and higher frequencies. However, because of the unique qualities of the markers according to the invention, there is an advantage to be obtained from resorting to lower rather than higher excitation frequencies. This follows from the fact that since the subject markers are relatively insensitive to the rate of change of the incident field, the subject~markers respond well to very low frequency exçitation. However, the low frequency, coupled with the same low field strengths as used theretofore, gives rise to smaller rather than larger rates of change of field, and this causes resp~nses from permalloy or other similar magnetic marker materials to become less rather than more readily detectable.
In this connection, it has been found that the wlre marker described above with reference to Fig. 3 will produce a signal pulse of less than ~400 Sec. duration when excited by a 1.2 Oe \~
_ ,~ _ .~,.
~4~32~
field at 20 Hz. This pulse is rich in harmonics. See the comparison shown in Fig. 14. Consequently, the wire of the invention is easily detected while prior art markers are essentially invisible to the same interrogation field.
By way of summary, for the purpose of providing an element useful as an article surveillance marker, in accordance with the present invention, the element should have a large Barkhausen discontinuity in its hysteresis loop. S~ch discontinuity should respond to a low level of field excitation, preferably below 1.0 oersted,!and should result in a reversal of magnetic polarization from the threshold excitation point to the maximum induction point for the element, or at least close to such maximum induction point. The element should be positive magnetostrictive. Finally, the geometry of the element should be such as to limit the demagnetizing factor to a very low level, preferably not in excess of 0.000125. While amorphous metal is presently preferred, the invention contemplates use of any material with which the mentioned perform~ce parameters can be obtained.
Satisfactory results have been obtained with amorphous wire mar~ers having the following compositions:
a) Fegl si4 B14 Cl;
b) Fegl Si4 Bls; and c) Fe77.s Si7.5 B15-However, it is believed that a wide range o~ such materials can _ ~ _ ' ~L'2~532~
be used, all falling within the general formula:
Fegs_x Six B15-y Cy~
where the percentages are in atomic percent, x ranges from about 3 to 1~, and y ranges from about O to 2.
Amorphouse metal has been known for use;in surveillance markers. However, -to the extent that information is available, it has been uniform practice by the manuacturers of surveillance marker material to subject the metal to a final, stress-relieving, annealing step to improve the mechanical parameters of the product. Such stress-relieving(annealing would eliminate any large ~arkhausen discontinuities that might have existed in the hysteresis loop of the element and lose herein desired magnetic characteristics, if it were of type discussed herein,e.g., amorphous metal wire obtained directly - from the rapid quench of molten metal and of desired dimensions.
In accordance with the invention, such wire or that annealed mechanically-stressed ribbon of Fig. 5 is used, without having its stress relieved, as surveillnace tag material and thereafter is deactivated by relievin~ such stress.
In the course of deactivation of an amorphous material marker in accordance with the invention, the unitary character of its active component,~ wlre 23 or ribbon 35, can be maintained and the chemical composition of the component persists unchanged. There occurs, however, a change in the molecular organization of the entire active component or a portion .
~2~532~
thereof. Thus, the entire marker active component or the portion thereof subjected to temperature elevation through current flow becomes molecularly ordered, i.e., is rendered Crystalline. The remainder of the component remains molecularly unorganized, i.e., amorphous. The magnetic,performance character of the marker is accordingly modified from that existing prior to deactivation, in effect, being transformed from a single active component into two active subcornponents separated from one another by the crystallized portion. The practice preferably is by use of a fast pulse of current which flash anneals, locally crystallizing a high coercive force band across the active component in contrast to the low coercive force prevailing in the remnant amorphous regions of the active component. As noted above, the entirety of the active component may be crystallized, in which case the coercive force prevailing throughout the component differs from its previous coercive force.
The system of the-invention is shown in block diagram in Fig. 15. A control or surveillance zone, e.g., an exit area of a store, is lndicated by broken lines at 66 and an article marker 67 of the above-discussed types is sh~wn in control ~one 66. The transmitter portion of the system includes frequency generator 68, the output of which is applied over line 69 to adjustable attenuator 70. The attenuator output, namely a desired level of the output of frequency generator 68, is S3'Z~
applied over line 71 to field generating coil 72, which accordingly establishes an alternating magnetic field in control zone 66.
The receiving portion of the system of Fig. 15 includes field receiving coil 73, the output of which is applied over line 74 to receiver 75. When the receiver detects harmonic content in signals received from coil 73 in a prescribed range, the receiver furnishes a triggering signal over line 76 to alarm unit 77.
Marker 78 is shown at a location outside of control zone 66 and accordingly not subject to the field established in ~one 66. An authorized checkout station includes marker deactivation unit 79 of the Fig. 15 system. A marker to be deactivated is introduced along path 80 into the deactivation unit and issued therefrom as deactivated marker 81, which now may pass freely through control zone 76 without acting upon the field therein in manner triggering aIarm unit 77.
A first embodiment of deactivation unit is shown in Fig. 16 as including an electrical power supply 82 having one output terminal grounded and a second output terminal connected through resistor 83 and capacitor 84 to ground. The supply, resistor and capacitor are selected to provide the desired output current pulse over line 85 when loaded by marker 86, shown in section and comprising the above-mentioned layers 21 and 22 and either wire 23 or ribbon 35. Insulation-piercing contacts 87 and 88 ~3 ~ _ 1~453Zl are provided, the former being connected to line 85 and the latter grounded. The capacitor will thus discharge into portion P of marker 86, elevating same to a temperature above the stress-relief temprature of the material comprising the marker active component. :;
A variation from the Fig. 16 deactivation unit is shown in Fig. 17. Here, the invention looks to preconditioning the marker for localized crystallization. Laser 89 has its output dlrected onto the portion of the marker 86 intended to be crystallized. The resultant local heating of the marker portion gives rise to an increase in the electrical reslstivity of the portion. Upon application of electrical current thereafter to the marker active componént, as long as contacts 87 and 88 straddle the preconditioned portion, the current induced heating will be localized at the portion of higher resistance and hence crystallization will be confined to a narrow range along the component. Where desired, full crystallization may be efected through the use of radiant energy, without subsequent application of current.
The deactivator embodiment of Flg. 18 is particularly useful for markers of type having locked-in stress. Here, the marker active component 35 is confined within heat-shrinkable laminates 90 and 91. Upon application of heat to the laminates from heating gun 92, the laminates shrink from their illustrated dimensions, thereby relaxing their constraint upon component 35 iL2'~53;~
and permitting the component to relax and to have its locked-in stress released. The resulting marker has vastly different magnetic response characteristics since its stress-induced magnetic discontinuity is no longer present. It will be understood that the release of locked-in stress may be achieved by other mechanical arrangements.
As noted above, in making markers of type having stress-induced magnetic discontinuity, an annealing step is employed at temperature level below the material crystallization temperature. Accordingly, the material retains its amorphous character to the point of deactivation, and the embodiments of Figs. 16 and 17 also apply for deactivation of this type of marker.
While the practices above discussed for deactivation have involved a change in the molecular organization of the marker active component, with the separation of the component into subcomponents of a body which remains unitary throughout the deactivation, the invention contemplates that one can actually cause physical separation of the component into separate bodies by use of the capacitor discharge of the Fig. 17 showing. The invention thus may be practiced by effecting molecular organization change in the course of deactivation involving additional effects, such as subsequent unitary body disruption.
It is to be appreciated, however, that such disruption is not required for deactivation, but may occur following modification . .
. .
~;~4532i of molecular organization, e.g., where the flash deactivation current pulse is of level sufficiently high to disrupt the unitary body after causing such change in molecular organization. Further, the invention contemplates deactivation of surveillance tag markers by modification:of molecular organization as between surveillance use state and deactivation state irrespective of the magnetic character exhibited by the marker during surveillance use, e.g., markers subject to deactivation by molecular reorganiæation and not exhibiting large Barkhausen discontinuities.
Various changes in structure and modifications in method may be introduced in the foregoing without departing from the invention. Accordingly, it is to be appreciated that the particularly depicted and described preferred embodiments and practices are intended in an illustrative and not in a limiting sense. The true spirit and scope of the invention is set forth in the following claims.
.
~b . .
In like manner, a ribbon of "Metglas" ductile amorphous metal produced by Allied Corporation of Morris Township, New Jersey, was subjected to the same levels of excitation, also at 60 Hz, and the resulting pulses are plotted in Figs. 7A, 7B, 7C
-~ *Trade Mark ~2~3Z~L
and 7D. The "Metglas" ribbon was 0.070" wide, 0.0007" thick, and 3.0" long. It was identified as "Metglas" strip/2826M~2, having a maximum permeability of 180,000, a coercivity, Hc, of 0.035 oersteds, and saturation magnetization of 9,000 Gauss.
Before discussing in further detail the~,wave shapes shown in Figs. 6 and 7 and their implication with regard to an article surveillance system, it will be useful to have an understanding of the present invention and the pulse forms thereby--obtainable~ Referring to Fig. 3, there is shown a marker 20 having a substrate 21 and an overlayer 22 that can be the same as the components 11 and 12, respectively, in Fig. 1, and can be attached to an article in similar fashion. However, instead of the ribbon 13, the active element in the embodiment of Fig. 3 is a length of amorphous metal wire 23. A sample used to provide the test data to be discussed was approximately 7.6 cm t3") long, has a diameter of 0.125 mm, and its composition satisfied the formula Fe81 Si4 B14 Cl, where the percentages are in atomic percent. These parameters should be considered only as representing one example~for the purpose of explanation since, as will appear from the ensuing discussion, the diameter can range between O.O9 and 0.15 mm while the length can range between about 2.5 and 10 cm for use as a surveillance marker.
The demagnetizing factor for the length of wire, 23, preferably does not exceed 0.000125. At present, however, the dimensions of the above sample are preferred for the wire 23.
What has been described so far is not unusual, but the _ ~ _ .. . ~ . ~ . , .
~2~532,~
particular wire used for the element 23 is unique in that it is characterized by a discontinuous hysteresis characteristic. Not by a slight discontinuity, but by a large Barkhausen discontinuity such that when the magnitude of an incident field of appropriate direction relative to the ma~netic polarity of the wire exceeds a low threshold value, in this case substantially less than 1.0 oersted, the magnetic polarity of the wire will reverse regeneratively, independent of--any further increase in the incident field, up to its maximum induction point. The threshold for the above sample is actually less than 0.6 oersted.
The nature of the hysteresis loop is shown in Fig. 4.
Again, the scale and proportions in Fig. 4 are grossly distorted from reality for the sake of convenience in explanation. Thus, the magnetizing field from the negative residual induction point 24 to the threshold point 25 is less than 1.0 oersted. Once the magnetizing field exceeds th~e threshold value for the smaple, there occurs an abrupt regenerative reversal of the polarity, represented by the broken line segment 26 of the hysteresis loop, until the maximum induction point 27 is reached. If the magnetizing field continues to increase above the threshold point, the flux density will increase toward the positive saturation point 28. Otherwise, the element 23 will head toward its positive residual induction point 29 as the magnitude of the magnetizing field approaches zero, and will remain there until ~LZ~532~
the magnetizing field departs from zero. If the magnetizing field now increases in the negative direction, the flux density will follow the stable portion of the loop to the negative threshold point 30 from which it shifts regeneratively and-substantially instantaneously along the broken line segment 31 to the negative maximum induction point 32 and then to a point between saturation at 33 and threshold 25 as a function of the magnetizing field.
It should now be apparent that change in the magnetic polarity of the wire 23 between either points 25 and 27 or 30 and 32 occurs independent of the rate of change of the magnetizing field. All that is important is that the magnetizing field exceed the threshold level of the particular wire element 23. This fact is borne out by the pulse forms obtained from the wire 23 under different Ievels of field excitation which pulse forms are shown in Fig. 8. While there is some difference between the sharpness or time duration of the signal spikes such differences are slight when a comparison is made with Figs. 6 and 7 showing the pulses from prior art marker strips.
The above-mentioned sample of wire 23 was 7.6 cm. long. It has been found that varying the length over the mentioned range will influence the hysteresis loop by chanaing the slope of the portions 28-30 and 33-25, shown in solid lines. As the wire is made shorter, the aforementioned slope will increase, while as 1~
3~
the wire is made longer, the slope in question will decrease.
Changing the aforesaid slope will alter the sharpness of the pulse. Thus, if a longer wire 23 can be tolerated and it is so desired, the differences between the pulses in the various parts of Fig. 8 can be reduced. However, it is ge.nerally the sensitivity and selectivity of the surveillance system in which the marker is to operate that determines what pulse wave shapes can be tolerated and that imposes a limit on the minimum length of wire. The wire 23 must be long enough to produce a pulse with sufficient definition that it can be detected by the detecting system.
While the pulses illustrated in Fig. 7 were from a test sample of amorphous metal, it did not have a Barkhausen discontinuity, and comparison with the pulses in Fig. 8, also from an amorphous metal but with a Barkhausen discontinuity, reveals a profound difference. The significant change in pulse width shown in Fig. 7 and the very close mimicking of the permalloy sample as the excitation is increased from 1.2 to 4.5 oersteds is but an indication that the "Metglas" sample did not have a Barkhausen discontinuity in its hysteresis characteristic. By contrast, Fig. 8 reveals the pxesence of a Barkhausen discontinuity, which is necessary~ at the specified levels and frequency of the exciting ~ield, to give rise to the extremely short duration pulses with comparatively little change in width over the exciting range.
.
_ ~_ .
3~i The invention is not limited to a wire marker. Instead, it encQmpasses any body of magnetic material having a large Barkhausen discontinuity in its hysteresis loop associated with a relatively low switching threshold, preferably no greater than about 1.0 oersted. For example, similar results can be obtained if the same material from which wire 23 was produced is used to producç a ribbon of amorphous metal such as shown in Fig. 5.
The ribbon designated 35 in Fig. 5, can be produced by any known method for rapidly quenching molten metal to avoid crystallization. Starting with a ribbon about 2 mm wide and about .025 mm thick between 3 and 10 cm long, it should be twisted up to 4 turns per 10 cm and annealed while so twisted, the annealing being performed at about 3~0C. for about 25 minutes. When cool, the ribbon should be untwisted and laminated within substrate and over ayer in a flat condition similar to that shown in Fig. 1. The flattened ribbon will have locked in stresses providing a helical easy axis of magnetization and giving rise to the subject discontinuities.
In other words, the ribbon or strip should have stress induced magnetic discontinuity when restrained in flattened condition.
In order to understand the implication o~ using the above described markers, having large hysteresis loop Barkhausen discontinuities, in an article surveillance system, it is helpful to examine the fre~uency spectra of the pulse signals obtained from such markers. For this purpose a testing system ; ~ If 1~53;~:1 was assembled as shown in Fig. 9. An adjustable fre~uency generator or source 40 was connected through an adjustable attenuator 41 to a field generating coil 42. With this arrangement a magnetizing field could be established within a controlled space having a desired ~requency,,and field strength.
By appropriate calibration and metering (not shown) known levels of excitation were obtainable at the position of the marker 43.
Any stimulation of the marker .43 resulting in field perturbation was detected by a suitable field receiving coil 44 whose output was coupled through a receiver'45 to a curve tracer and spectrum analyzer 46. This system was used to produce the curves in Figs. 6, 7, 8 and 14 as well as the spectrograms of Figs. 10 to 12.
Referri~g now to Figs. 10 to 12, they constitute spectrograms of the pulse trains obtained from the prior art markers and a marker according to the invention when such markers were excited by magnetizing fields of fixed frequency ~60 Hz) and various levels of field excitation. The frequency of the harmonic component is plotted along the x-axis while the pea~ amplitude of the harmonic is plotted along the y-axis.
However, the x-axis has a zero offset with the origin corresponding to 60 Hæ, the fundamental fre~uency, so that the ~irst component to the right, designated by the numeral 50 in Fig. lOA, corresponds to the 2nd harmonic at 120 Hz.' A series of dots above a bar line signifies that the amplitude exceeded 1~
,~
. . :
~2~5~Z~
the range covered by the graph.
If Fig. 10 is examined, it reveals how field strength dependent is the output from prior art permalloy strip markers.
The same marker element was used for these spectrograms as was described with re~erence to Fig. 6. Thus, when subjected to 0.6 oersted field excitation the permalloy strip produced a pulse in which the 33rd harmonic was the highest detectable with sufficient amplitude not to be masked by background noise in a surveillance system. At an excitation of 1.2 oersted as shown in Fig. lOB, the 33rd harmonic is still the highest detectable, although there is a stronger presence of the low order harm~nics. The magnitude of the 33rd harmonic, however, has remained essentially the same as at the lower 0.6 oersted excitation. The 63rd harmonic is noticeable at 2.4 oersteds ~Fig. lOC), while at an excitation of 4.5 oersteds (Fig. lOD) the 99th harmonic is beginning to appear.
Now, compare with Fig. ao the corresponding spectrograms for the marker according to the invention as shown in Fig. 11. With the invention, at every level of excitation, from 0.6 oersted on up, harmonics on out as far as the 99th harmonic are present with significant amplitude to be readily detectable. whether the pulse envelopes of Fig. 8 are compared with those of Fig. 6, or the spectrograms of Fig. 11 are compared with those of Fig.
10, the differences are readily perceived. With the invention, a broad band of higher order harmonics appears at a relatively 1~
~2~S3;~1 low level of magnetizing field excitation, an excitation level below that level at which prior art permalloy strips produce any significant detectable output. Consequently, a detection system can be assembled to detect the new marker wlthout interference by permalloy strips or any other similar prior art marker. An example of a system is shown in Fig. 13 wherein a low frequency generator 60 of 60 Hz signal drives a field generating coil 61.
When a marker 20 is in the field from coil 61, its perturbations are received by a field receiving coil 62 whose output is passed through a high pass filter circuit 63 having a suitable cutoff ~requency. Signals passed by filter 63 are supplied to a frequency selection/detection circuit 64. Depending upon the screen provided in circuit 64, when a predetermined pattern of fre~uency, amplitude and/or pulse duration is detected~ the circuit 64 will furnish an output to activate an alarm 65. From a consideration of the graphs of Figs. 10 and 11 it should be evident that the unique markers according to the invention can be detected by systems that can be made immune to permalloy strips. Also, from a consideration of Fig. 11, it should be evident that the response of the invention marker is detectab~e over a wide range of magnetizing field strength.
Referring now to Fig. 12, there is shown the corresponding frequency spectra that was obtained from the "Metglas" ductile amorphous metal sample. At an excitation of 0.6 oersteds the highest order harmonic detectable with any significant amplitude 1~5~Z~
is the 26th. At 1.2 oersteds excitation the 29th harmonic has appeared, while the 33rd harmonic first appears at 2.4 oersted excitation. At the maximum excitation of 4.5 oersteds, the highest noticeable harmonic is the 65th. The overall spectral pattern bears an extremely close resemblanc~ to that shown in Fig. 10 for permalloy, and cannot be mistaken for the drastically different spectrum shown in Fig. 11 for the invention.
The dependency of prior art markers on time rate of change f the incident field has led prior workers in the article surveillance field toward the use of higher and higher frequencies. However, because of the unique qualities of the markers according to the invention, there is an advantage to be obtained from resorting to lower rather than higher excitation frequencies. This follows from the fact that since the subject markers are relatively insensitive to the rate of change of the incident field, the subject~markers respond well to very low frequency exçitation. However, the low frequency, coupled with the same low field strengths as used theretofore, gives rise to smaller rather than larger rates of change of field, and this causes resp~nses from permalloy or other similar magnetic marker materials to become less rather than more readily detectable.
In this connection, it has been found that the wlre marker described above with reference to Fig. 3 will produce a signal pulse of less than ~400 Sec. duration when excited by a 1.2 Oe \~
_ ,~ _ .~,.
~4~32~
field at 20 Hz. This pulse is rich in harmonics. See the comparison shown in Fig. 14. Consequently, the wire of the invention is easily detected while prior art markers are essentially invisible to the same interrogation field.
By way of summary, for the purpose of providing an element useful as an article surveillance marker, in accordance with the present invention, the element should have a large Barkhausen discontinuity in its hysteresis loop. S~ch discontinuity should respond to a low level of field excitation, preferably below 1.0 oersted,!and should result in a reversal of magnetic polarization from the threshold excitation point to the maximum induction point for the element, or at least close to such maximum induction point. The element should be positive magnetostrictive. Finally, the geometry of the element should be such as to limit the demagnetizing factor to a very low level, preferably not in excess of 0.000125. While amorphous metal is presently preferred, the invention contemplates use of any material with which the mentioned perform~ce parameters can be obtained.
Satisfactory results have been obtained with amorphous wire mar~ers having the following compositions:
a) Fegl si4 B14 Cl;
b) Fegl Si4 Bls; and c) Fe77.s Si7.5 B15-However, it is believed that a wide range o~ such materials can _ ~ _ ' ~L'2~532~
be used, all falling within the general formula:
Fegs_x Six B15-y Cy~
where the percentages are in atomic percent, x ranges from about 3 to 1~, and y ranges from about O to 2.
Amorphouse metal has been known for use;in surveillance markers. However, -to the extent that information is available, it has been uniform practice by the manuacturers of surveillance marker material to subject the metal to a final, stress-relieving, annealing step to improve the mechanical parameters of the product. Such stress-relieving(annealing would eliminate any large ~arkhausen discontinuities that might have existed in the hysteresis loop of the element and lose herein desired magnetic characteristics, if it were of type discussed herein,e.g., amorphous metal wire obtained directly - from the rapid quench of molten metal and of desired dimensions.
In accordance with the invention, such wire or that annealed mechanically-stressed ribbon of Fig. 5 is used, without having its stress relieved, as surveillnace tag material and thereafter is deactivated by relievin~ such stress.
In the course of deactivation of an amorphous material marker in accordance with the invention, the unitary character of its active component,~ wlre 23 or ribbon 35, can be maintained and the chemical composition of the component persists unchanged. There occurs, however, a change in the molecular organization of the entire active component or a portion .
~2~532~
thereof. Thus, the entire marker active component or the portion thereof subjected to temperature elevation through current flow becomes molecularly ordered, i.e., is rendered Crystalline. The remainder of the component remains molecularly unorganized, i.e., amorphous. The magnetic,performance character of the marker is accordingly modified from that existing prior to deactivation, in effect, being transformed from a single active component into two active subcornponents separated from one another by the crystallized portion. The practice preferably is by use of a fast pulse of current which flash anneals, locally crystallizing a high coercive force band across the active component in contrast to the low coercive force prevailing in the remnant amorphous regions of the active component. As noted above, the entirety of the active component may be crystallized, in which case the coercive force prevailing throughout the component differs from its previous coercive force.
The system of the-invention is shown in block diagram in Fig. 15. A control or surveillance zone, e.g., an exit area of a store, is lndicated by broken lines at 66 and an article marker 67 of the above-discussed types is sh~wn in control ~one 66. The transmitter portion of the system includes frequency generator 68, the output of which is applied over line 69 to adjustable attenuator 70. The attenuator output, namely a desired level of the output of frequency generator 68, is S3'Z~
applied over line 71 to field generating coil 72, which accordingly establishes an alternating magnetic field in control zone 66.
The receiving portion of the system of Fig. 15 includes field receiving coil 73, the output of which is applied over line 74 to receiver 75. When the receiver detects harmonic content in signals received from coil 73 in a prescribed range, the receiver furnishes a triggering signal over line 76 to alarm unit 77.
Marker 78 is shown at a location outside of control zone 66 and accordingly not subject to the field established in ~one 66. An authorized checkout station includes marker deactivation unit 79 of the Fig. 15 system. A marker to be deactivated is introduced along path 80 into the deactivation unit and issued therefrom as deactivated marker 81, which now may pass freely through control zone 76 without acting upon the field therein in manner triggering aIarm unit 77.
A first embodiment of deactivation unit is shown in Fig. 16 as including an electrical power supply 82 having one output terminal grounded and a second output terminal connected through resistor 83 and capacitor 84 to ground. The supply, resistor and capacitor are selected to provide the desired output current pulse over line 85 when loaded by marker 86, shown in section and comprising the above-mentioned layers 21 and 22 and either wire 23 or ribbon 35. Insulation-piercing contacts 87 and 88 ~3 ~ _ 1~453Zl are provided, the former being connected to line 85 and the latter grounded. The capacitor will thus discharge into portion P of marker 86, elevating same to a temperature above the stress-relief temprature of the material comprising the marker active component. :;
A variation from the Fig. 16 deactivation unit is shown in Fig. 17. Here, the invention looks to preconditioning the marker for localized crystallization. Laser 89 has its output dlrected onto the portion of the marker 86 intended to be crystallized. The resultant local heating of the marker portion gives rise to an increase in the electrical reslstivity of the portion. Upon application of electrical current thereafter to the marker active componént, as long as contacts 87 and 88 straddle the preconditioned portion, the current induced heating will be localized at the portion of higher resistance and hence crystallization will be confined to a narrow range along the component. Where desired, full crystallization may be efected through the use of radiant energy, without subsequent application of current.
The deactivator embodiment of Flg. 18 is particularly useful for markers of type having locked-in stress. Here, the marker active component 35 is confined within heat-shrinkable laminates 90 and 91. Upon application of heat to the laminates from heating gun 92, the laminates shrink from their illustrated dimensions, thereby relaxing their constraint upon component 35 iL2'~53;~
and permitting the component to relax and to have its locked-in stress released. The resulting marker has vastly different magnetic response characteristics since its stress-induced magnetic discontinuity is no longer present. It will be understood that the release of locked-in stress may be achieved by other mechanical arrangements.
As noted above, in making markers of type having stress-induced magnetic discontinuity, an annealing step is employed at temperature level below the material crystallization temperature. Accordingly, the material retains its amorphous character to the point of deactivation, and the embodiments of Figs. 16 and 17 also apply for deactivation of this type of marker.
While the practices above discussed for deactivation have involved a change in the molecular organization of the marker active component, with the separation of the component into subcomponents of a body which remains unitary throughout the deactivation, the invention contemplates that one can actually cause physical separation of the component into separate bodies by use of the capacitor discharge of the Fig. 17 showing. The invention thus may be practiced by effecting molecular organization change in the course of deactivation involving additional effects, such as subsequent unitary body disruption.
It is to be appreciated, however, that such disruption is not required for deactivation, but may occur following modification . .
. .
~;~4532i of molecular organization, e.g., where the flash deactivation current pulse is of level sufficiently high to disrupt the unitary body after causing such change in molecular organization. Further, the invention contemplates deactivation of surveillance tag markers by modification:of molecular organization as between surveillance use state and deactivation state irrespective of the magnetic character exhibited by the marker during surveillance use, e.g., markers subject to deactivation by molecular reorganiæation and not exhibiting large Barkhausen discontinuities.
Various changes in structure and modifications in method may be introduced in the foregoing without departing from the invention. Accordingly, it is to be appreciated that the particularly depicted and described preferred embodiments and practices are intended in an illustrative and not in a limiting sense. The true spirit and scope of the invention is set forth in the following claims.
.
~b . .
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A marker for use in an article surveillance system in which an alternating magnetic field is established in a surveillance region and an alarm is activated when a predetermined perturbation to said field is detected, said marker comprising a body of magnetic material with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that exposure of said body to an external magnetic field, whose field strength in the direction opposing the magnetic polarization of said body exceeds a predetermined threshold value, results in regenerative reversal of said magnetic polarization, and means for securing said body to an article to be maintained under surveillance.
2. The invention claimed in claim 1 wherein said body comprises an amorphous metal.
3. The invention claimed in claim 2 wherein said body comprises a length of wire.
4. The invention claimed in claim 1 wherein said body comprises a length of amorphous metal ribbon.
5. The invention claimed in claim 4 characterized in that said ribbon when restrained in a flat position has a helical easy axis of magnetization resulting from annealing said ribbon while twisted to relax helical stresses resulting from said twisting and thereafter untwisting.
6. The invention claimed in claim 1 wherein said body comprises a length of an amorphous metal which, due to its manufacturing history, has said retained stress.
7. The invention claimed in claim 3 wherein said wire has a diameter within the range of 0.09 to 0.15 mm and a length within range of 1 to 10 cm.
8. The invention claimed in claim 3 wherein the demagnetizing factor for said length of wire does not exceed 0.000125.
9. The invention claimed in claim 2 wherein the metallurgical composition of said body is essentially given by the formula Fe85-x Six B15-y Cy, where the percentages are in atomic percent, x ranges from about 3 to 10, and y ranges from about 0 to 2.
10. The invention claimed in claim 1 wherein said marker is deactivatable by modification of the molecular organization of at least a portion of said body.
11. The invention claimed in claim 2 wherein said body is deactivatable by rendering crystalline at least a portion thereof.
12. The invention claimed in claim 1 wherein said body is decativatable by relieving said retained stress.
13. The invention claimed in claim 1 wherein said body is a length of amorphous metal ribbon supported in a magnetic Barkhausen discontinuity inducing stressed condition and is deactivatable by relieving said retained stress in said body.
14. An electronic article surveillance system operative with the marker of claim 1 for detection of said marker comprising (a) transmitting means for establishing an alternating magnetic field of intensity in excess of the predetermined threshold value in a control zone of interest; and (b) receiving means for detection in said control zone of the presence of such marker.
15. The invention claimed in claim 14 with means for modifying the molecular organization of said marker component, thereby deactivating said marker.
16. The invention claimed in claim 15 wherein such deactivation means includes means for modifying the molecular organization of at least a portion of said marker component.
17. The invention claimed in claim 14 wherein said marker comprises an amorphous ferromagnetic material with means for crystallizing at least a portion of said marker, thereby deactivating said marker.
18. The invention claimed in claim 16 wherein said decativation means comprises an electric current supply for selective electrical connection to said portion of said marker component.
19. The invention claimed in claim 17 wherein said current supply is operable at such current level as to maintain such portion of said marker component at a temperature above the crystallization temparature of said component and thereby to crystallize a coercive force in said portion different from the coercive force in the remainder of said component.
20. The invention claimed in claim 15 wherein such deactivation means comprises means for applying radiant energy to said marker component.
21. The invention claimed in claim 14 in which means are provided for deactivating said marker by relieving the retained stress.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/675,005 US4660025A (en) | 1984-11-26 | 1984-11-26 | Article surveillance magnetic marker having an hysteresis loop with large Barkhausen discontinuities |
| US675,005 | 1984-11-26 | ||
| US06/761,611 US4686516A (en) | 1984-11-26 | 1985-08-01 | Method, system and apparatus for use in article surveillance |
| US761,611 | 1985-08-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1245321A true CA1245321A (en) | 1988-11-22 |
Family
ID=27101256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000496093A Expired CA1245321A (en) | 1984-11-26 | 1985-11-25 | Method, system and apparatus for use in article surveillance |
Country Status (13)
| Country | Link |
|---|---|
| US (1) | US4686516A (en) |
| KR (1) | KR900005650B1 (en) |
| AR (1) | AR241392A1 (en) |
| BE (1) | BE903717A (en) |
| BR (1) | BR8505914A (en) |
| CA (1) | CA1245321A (en) |
| DE (3) | DE3546642C2 (en) |
| ES (2) | ES8802097A1 (en) |
| FR (1) | FR2573895A1 (en) |
| GB (1) | GB2167627B (en) |
| IT (1) | IT1201385B (en) |
| NL (1) | NL193508C (en) |
| SE (1) | SE502894C2 (en) |
Families Citing this family (61)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4769631A (en) * | 1986-06-30 | 1988-09-06 | Sensormatic Electronics Corporation | Method, system and apparatus for magnetic surveillance of articles |
| EP0287905B1 (en) * | 1987-04-23 | 1993-03-03 | Actron Entwicklungs AG | Method for deactivating a resonant target, and circuit for carrying out this method |
| DE3723310A1 (en) * | 1987-07-15 | 1989-01-26 | John Urquhart | PHARMACEUTICAL PREPARATION AND METHOD FOR THE PRODUCTION THEREOF |
| DE3828691B4 (en) * | 1987-08-28 | 2004-11-25 | Sensormatic Electronics Corp., Boca Raton | Electronic article surveillance system |
| US4859991A (en) * | 1987-08-28 | 1989-08-22 | Sensormatic Electronics Corporation | Electronic article surveillance system employing time domain and/or frequency domain analysis and computerized operation |
| US4980670A (en) * | 1987-11-04 | 1990-12-25 | Sensormatic Electronics Corporation | Deactivatable E.A.S. marker having a step change in magnetic flux |
| DE3741780A1 (en) * | 1987-12-10 | 1989-06-29 | Karl Harms Handels Gmbh & Co K | MAGNETIC THEFT OR BURGLAR SECURITY SYSTEM AND SENSOR METAL ELEMENT SUITABLE FOR THIS |
| ATE93066T1 (en) * | 1988-04-18 | 1993-08-15 | Security Tag Systems Inc | FREQUENCY-DIVING RESPONDER WITH AN AMORPHIC WIRE FOR APPLICATION IN A PRESENCE DETECTION SYSTEM. |
| US4899134A (en) * | 1988-08-04 | 1990-02-06 | Wheeless Jr Clifford R | Newborn anti-theft device |
| US5003291A (en) * | 1988-12-27 | 1991-03-26 | Strom Olsen John O | Ferromagnetic fibers having use in electronical article surveillance and method of making same |
| GB8923155D0 (en) * | 1989-10-13 | 1989-11-29 | Emi Plc Thorn | Improvements in or relating to financial transaction cards |
| US5029291A (en) * | 1990-04-10 | 1991-07-02 | Knogo Corporation | Electromagnetic sensor element and methods and apparatus for making and using same |
| CH682957A5 (en) * | 1991-04-16 | 1993-12-15 | Kobe Properties Ltd | Method for deactivating a resonant tag. |
| TW198154B (en) * | 1991-08-20 | 1993-01-11 | Allied Signal Inc | |
| US5304983A (en) * | 1991-12-04 | 1994-04-19 | Knogo Corporation | Multiple pulse responder and detection system and method of making and using same |
| JPH06282229A (en) * | 1993-01-27 | 1994-10-07 | Unitika Ltd | Anti-theft label |
| SE9401450L (en) * | 1994-04-26 | 1995-10-27 | Rso Corp | Method of detecting magnetic elements |
| US5428346A (en) * | 1993-05-28 | 1995-06-27 | Sealed Air Corporation | Theft alarm activating absorbent pad |
| SE9401436L (en) * | 1994-04-26 | 1995-10-27 | Rso Corp | Amorphous bands with improved properties |
| SE9401449L (en) * | 1994-04-26 | 1995-10-27 | Rso Corp | Methods and apparatus for encoding electronic labels |
| SE9401448L (en) * | 1994-04-26 | 1995-10-27 | Rso Corp | Methods and apparatus for excitation and detection of magnetic elements |
| US5532598A (en) * | 1994-05-25 | 1996-07-02 | Westinghouse Electric Corporation | Amorphous metal tagging system for underground structures including elongated particles of amorphous metal embedded in nonmagnetic and nonconductive material |
| US5565849A (en) * | 1995-02-22 | 1996-10-15 | Sensormatic Electronics Corporation | Self-biased magnetostrictive element for magnetomechanical electronic article surveillance systems |
| US5528914A (en) | 1994-09-27 | 1996-06-25 | Sensormatic Electronics Corporation | Security tag and complemental deactivation apparatus |
| US6310963B1 (en) * | 1994-09-30 | 2001-10-30 | Sensormatic Electronics Corp | Method and apparatus for detecting an EAS (electronic article surveillance) marker using wavelet transform signal processing |
| SE503526C2 (en) * | 1994-10-26 | 1996-07-01 | Rso Corp | Ways of detecting labels with amorphous magnetoelastic bands |
| US5729201A (en) * | 1995-06-29 | 1998-03-17 | International Business Machines Corporation | Identification tags using amorphous wire |
| US5949334A (en) * | 1995-10-02 | 1999-09-07 | Sensormatic Electronics Corporation | Magnetostrictive element having optimized bias-field-dependent resonant frequency characteristic |
| CA2189827A1 (en) * | 1995-11-08 | 1997-05-09 | Tatsuya Matsumoto | Antitheft label |
| BR9605445A (en) | 1995-11-08 | 1998-08-04 | Unitika Ltd | Continuous marker for use in a labeling apparatus and labeling system |
| JPH09180936A (en) | 1995-12-27 | 1997-07-11 | Unitika Ltd | Magnetic element |
| JPH09232141A (en) * | 1996-02-28 | 1997-09-05 | Unitika Ltd | Magnetic element |
| US5821859A (en) * | 1996-06-07 | 1998-10-13 | Ibm Corporation | Concealed magnetic ID code and antitheft tag |
| CA2216897A1 (en) * | 1996-09-30 | 1998-03-30 | Unitika Ltd. | Fe group-based amorphous alloy ribbon and magnetic marker |
| US5801630A (en) * | 1996-11-08 | 1998-09-01 | Sensormatic Electronics Corporation | Article surveillance magnetic marker having an hysteresis loop with large barkhausen discontinuities at a low field threshold level |
| JPH10222283A (en) * | 1997-01-31 | 1998-08-21 | Seiko Denshi Kiki Kk | Coordinate reader and its coordinate indicator |
| SE9700542L (en) * | 1997-02-17 | 1998-08-18 | Rso Corp | Method of deactivating an item monitoring sensor |
| FR2766581B1 (en) * | 1997-07-24 | 1999-09-10 | Stefil | DEVICE FOR PROTECTING OBJECTS AGAINST THEFT |
| HUP9701312A3 (en) * | 1997-07-28 | 2000-06-28 | Magyar Allamvasutak Reszvenyta | Method for complex shaping of marks or a system of marks by means of modifying texture and inner stresses in materials and by non-destructive read-out of marks or packets of marks |
| US6137413A (en) | 1998-10-29 | 2000-10-24 | Sensormatic Electronics Corporation | Cap with integrated eas marker |
| EP1258538B1 (en) * | 2000-07-17 | 2006-10-11 | NHK Spring Co., Ltd. | Magnetic marker and its manufacturing method |
| US6373390B1 (en) | 2000-08-08 | 2002-04-16 | Sensormatic Electronics Corporation | Electronic article surveillance tag having arcuate channel |
| US6535130B2 (en) | 2001-04-25 | 2003-03-18 | Sensormatic Electronics Corporation | Security apparatus for electronic article surveillance tag |
| EP1463962A2 (en) | 2001-12-10 | 2004-10-06 | Innovision Research & Technology PLC | Detectable components and detection apparatus for detecting such components |
| US6752837B2 (en) | 2002-06-28 | 2004-06-22 | Hewlett-Packard Development Company, L.P. | Security tags with a reversible optical indicator |
| US7126479B2 (en) * | 2004-08-17 | 2006-10-24 | Francis M. Claessens | Metal container closure having integral RFID tag |
| US7061382B2 (en) * | 2003-12-12 | 2006-06-13 | Francis M. Claessens | Apparatus for electronically verifying the authenticity of contents within a container |
| US7017807B2 (en) * | 2003-09-08 | 2006-03-28 | Francis M. Claessens | Apparatus and method for detecting tampering with containers and preventing counterfeiting thereof |
| JP4489082B2 (en) * | 2003-12-12 | 2010-06-23 | クレセンス、フランシス・エム | A device for electronically determining whether a tax has been paid on a product |
| US7068172B2 (en) * | 2004-05-21 | 2006-06-27 | Xiao Hui Yang | Method and apparatus for deactivating an EAS device |
| ES2268964B1 (en) | 2005-04-21 | 2008-04-16 | Micromag 2000, S.L. | "ACTIVABLE / DEACTIVABLE MAGNETIC LABEL BASED ON MAGNETIC MICROWAVE AND METHOD OF OBTAINING THE SAME". |
| US7633396B2 (en) * | 2006-02-07 | 2009-12-15 | Sensormatic Electronics, LLC | Electronic article surveillance tag having an expulsion detrimental substance system with substance routing system |
| ES2317769B1 (en) | 2006-12-15 | 2010-02-03 | Micromag 2000, S.L. | MAGNETOACUSTIC LABEL BASED ON MAGNETIC MICRO-THREAD, AND METHOD OF OBTAINING THE SAME. |
| EP2081191A1 (en) | 2008-01-21 | 2009-07-22 | Tecnicas Pantra S.L. | Non symmetric devices with alarms for compact discs and similar articles |
| US20090212952A1 (en) * | 2008-02-22 | 2009-08-27 | Xiao Hui Yang | Method and apparatus for de-activating eas markers |
| US8089362B2 (en) * | 2009-04-08 | 2012-01-03 | Avery Dennison Corporation | Merchandise security kit |
| BR112012000038A2 (en) | 2009-07-03 | 2016-03-15 | Nestec Sa | a beverage preparation capsule comprising an identification element |
| EP2355064A1 (en) * | 2010-02-03 | 2011-08-10 | Nxp B.V. | A method of de-activating and activating an electronic article surveillance (esa) device, and an eas device |
| DE102014014913B3 (en) | 2014-10-08 | 2015-09-17 | Alexander Schneider | Seal for securing goods |
| CN105469702A (en) * | 2016-01-09 | 2016-04-06 | 赵晓旭 | Magnetic sealing patch |
| ES2581127B2 (en) | 2016-04-13 | 2017-05-04 | Universidad Complutense De Madrid | Label, system and method for long-distance object detection |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1330482A (en) * | 1969-07-11 | 1973-09-19 | Minnesota Mining & Mfg | Apparatus for detecting the status and identity of objects |
| US3624631A (en) * | 1970-04-27 | 1971-11-30 | Sanders Associates Inc | Pilferage control system |
| US4053331A (en) * | 1974-09-20 | 1977-10-11 | University Of Pennsylvania | Method of making amorphous metallic alloys having enhanced magnetic properties by using tensile stress |
| NL7702946A (en) * | 1976-04-03 | 1977-10-05 | Bizerba Werke Kraut Kg Wilh | METHOD AND ARRANGEMENT FOR DETERMINING THE PRESENCE OF OBJECTS IN A PARTICULAR CONTROL AREA, IN PARTICULAR FOR PREVENTION OF SHOP THEFT. |
| DE2641876C3 (en) | 1976-09-17 | 1979-05-23 | Bizerba-Werke Wilhelm Kraut Kg, 7460 Balingen | Deactivable marking element for the detection of objects in a surveillance area, in particular to prevent shoplifting |
| DE2709522C3 (en) * | 1977-03-04 | 1980-02-21 | Woerl Geb. Mueller, Waltraud, 8031 Stockdorf | Annex for reporting marking bodies |
| US4484184A (en) * | 1979-04-23 | 1984-11-20 | Allied Corporation | Amorphous antipilferage marker |
| US4298862A (en) * | 1979-04-23 | 1981-11-03 | Allied Chemical Corporation | Amorphous antipilferage marker |
| GB2080075A (en) * | 1980-07-10 | 1982-01-27 | Evans Samuel Cornelious | Improved Magnetic Marker |
| US4289862A (en) * | 1980-07-14 | 1981-09-15 | Ethyl Corporation | Liquid phosphazene compositions |
| US4342904A (en) * | 1980-10-27 | 1982-08-03 | Minnesota Mining And Manufacturing Company | Lightweight ferromagnetic marker for the detection of objects having markers secured thereto |
| US4510489A (en) * | 1982-04-29 | 1985-04-09 | Allied Corporation | Surveillance system having magnetomechanical marker |
| JPS58219677A (en) * | 1982-06-03 | 1983-12-21 | アイデンテイテツク コ−ポレ−シヨン | Coded monitor system with magnetomechanical marker |
| US4553136A (en) * | 1983-02-04 | 1985-11-12 | Allied Corporation | Amorphous antipilferage marker |
| CA1234891A (en) * | 1983-10-20 | 1988-04-05 | 746278 Ontario Limited D/B/A I.D. Systems Canada | Security system label |
| US4622543A (en) * | 1984-03-22 | 1986-11-11 | Anderson Iii Philip M | Surveillance system having acoustic magnetomechanical marker |
-
1985
- 1985-08-01 US US06/761,611 patent/US4686516A/en not_active Expired - Lifetime
- 1985-11-25 GB GB8528979A patent/GB2167627B/en not_active Expired
- 1985-11-25 DE DE3546642A patent/DE3546642C2/de not_active Revoked
- 1985-11-25 SE SE8505551A patent/SE502894C2/en not_active IP Right Cessation
- 1985-11-25 ES ES549240A patent/ES8802097A1/en not_active Expired
- 1985-11-25 CA CA000496093A patent/CA1245321A/en not_active Expired
- 1985-11-25 DE DE19853541536 patent/DE3541536A1/en active Granted
- 1985-11-25 IT IT09526/85A patent/IT1201385B/en active
- 1985-11-25 DE DE3546746A patent/DE3546746C2/de not_active Expired - Fee Related
- 1985-11-26 BE BE0/215915A patent/BE903717A/en not_active IP Right Cessation
- 1985-11-26 BR BR8505914A patent/BR8505914A/en not_active IP Right Cessation
- 1985-11-26 NL NL8503268A patent/NL193508C/en not_active IP Right Cessation
- 1985-11-26 AR AR85302383A patent/AR241392A1/en active
- 1985-11-26 FR FR8517458A patent/FR2573895A1/en active Granted
- 1985-11-26 KR KR1019850008821A patent/KR900005650B1/en not_active IP Right Cessation
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1987
- 1987-12-31 ES ES557794A patent/ES8900074A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| KR900005650B1 (en) | 1990-08-01 |
| US4686516A (en) | 1987-08-11 |
| NL8503268A (en) | 1986-06-16 |
| ES8900074A1 (en) | 1988-11-16 |
| BR8505914A (en) | 1986-08-19 |
| ES549240A0 (en) | 1988-03-16 |
| NL193508B (en) | 1999-08-02 |
| KR860004311A (en) | 1986-06-20 |
| IT8509526A0 (en) | 1985-11-25 |
| DE3546746C2 (en) | 1990-02-15 |
| ES8802097A1 (en) | 1988-03-16 |
| NL193508C (en) | 1999-12-03 |
| GB8528979D0 (en) | 1986-01-02 |
| ES557794A0 (en) | 1988-11-16 |
| GB2167627A (en) | 1986-05-29 |
| DE3541536C2 (en) | 1990-02-08 |
| SE8505551L (en) | 1986-05-27 |
| DE3541536A1 (en) | 1986-06-05 |
| FR2573895B1 (en) | 1994-11-25 |
| SE8505551D0 (en) | 1985-11-25 |
| IT1201385B (en) | 1989-01-27 |
| BE903717A (en) | 1986-03-14 |
| AR241392A1 (en) | 1992-06-30 |
| FR2573895A1 (en) | 1986-05-30 |
| GB2167627B (en) | 1989-06-14 |
| DE3546642C2 (en) | 1990-02-08 |
| SE502894C2 (en) | 1996-02-12 |
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| MKEX | Expiry |