CA1196986A - Amorphous antipilferage marker - Google Patents
Amorphous antipilferage markerInfo
- Publication number
- CA1196986A CA1196986A CA000414116A CA414116A CA1196986A CA 1196986 A CA1196986 A CA 1196986A CA 000414116 A CA000414116 A CA 000414116A CA 414116 A CA414116 A CA 414116A CA 1196986 A CA1196986 A CA 1196986A
- Authority
- CA
- Canada
- Prior art keywords
- atom
- ranges
- marker
- interrogation zone
- magnetic
- 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
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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
- 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
- G08B13/2411—Tag deactivation
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C45/00—Amorphous alloys
- C22C45/02—Amorphous alloys with iron as the major constituent
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
- H01F1/147—Alloys characterised by their composition
- H01F1/153—Amorphous metallic alloys, e.g. glassy metals
- H01F1/15308—Amorphous metallic alloys, e.g. glassy metals based on Fe/Ni
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Electromagnetism (AREA)
- Computer Security & Cryptography (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Dispersion Chemistry (AREA)
- Power Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Burglar Alarm Systems (AREA)
Abstract
ABSTRACT
AMORPHOUS ANTIPILFERAGE MARKER
A magnetic theft detection system marker is adapted to generate magnetic fields at frequencies that (1) are harmonically related to an incident mag-netic field applied within an interrogation zone and (2) have selected tones that provide the marker with signal identity. The marker is an elongated, ductile strip of amorphous ferromagnetic material having a composition defined by the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g"
ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)]
is less than about 0.84.
AMORPHOUS ANTIPILFERAGE MARKER
A magnetic theft detection system marker is adapted to generate magnetic fields at frequencies that (1) are harmonically related to an incident mag-netic field applied within an interrogation zone and (2) have selected tones that provide the marker with signal identity. The marker is an elongated, ductile strip of amorphous ferromagnetic material having a composition defined by the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g"
ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)]
is less than about 0.84.
Description
DESCRIPTION
AMC)RPHOUS AMTIPILFERAGE MARKER
BACKGROUND OF THE INVENTION
1. Field of the Inventlon This invention relates to antipilferage systems and markers for use therein. More particularly, the invention provides ductile, amorphous metal markers that enchance the sensitivity and reliability of the antipilferage system. The markers contain lower pro-portions of costly and stategic metals.
AMC)RPHOUS AMTIPILFERAGE MARKER
BACKGROUND OF THE INVENTION
1. Field of the Inventlon This invention relates to antipilferage systems and markers for use therein. More particularly, the invention provides ductile, amorphous metal markers that enchance the sensitivity and reliability of the antipilferage system. The markers contain lower pro-portions of costly and stategic metals.
2. Description of the Prior Art Theft of articles such as books, wearing apparel, appliances and the like from retail stores and state-funded institutions is a serious problem. The cost of replacing stolen articles and the impairment of services rendered by institutions such as libraries exceeds $6 billion annually and is increasing.
Systems employed to prevent ~heft of articles generally comprise a marker element secured to an object to ~e detec~ed and instruments adapted to sense a signal produced by the marker upon passage thereof through an interrogation ~one~
One of the major problems with such theft detection systems is the low signal level produced by the marker. This limits the sensitivity and reliability of the theft detection system~ Ancther problem is the dificulty of preventing degradation of the maker signal.
If the marker is broken or bent, the signal can be lost or altered in a manner that impairs its identifying 6~6 characteristics. Such bending or breaking of the marker can occur inadvertently during manufacture of the marker and subsequent handling of merchandise by employees and ~ustomers, or purposely in connection with attempted theft of goods. The present invention is directed to overcoming the foregoing problems.
SUMMARY OF THE INVENTION
.
BrieEly stated, the invention provides an amorphous ferromagnetic metal marker capable of produc-ing identifying signal characteristics in the presenceof an applied magnetic field. The marker comprises an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula FeaCrbccPdMoecufB9sih where "a" ranges from about 63-81 a~om %, "b" ranges from about 0-10 atom ~, ~c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e~ ranges from about 0-2 atom ~, "f " ranges from about 0-1 atom ~, 119~ ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c~d+g~h) ranges from 19-24 atom % and the fraction [c/(c~d-~g+h)] is less than about 0.84.
The marker is capable of producing magnetic fields at fre~uencies which are harmonics of the frequency of an incident field. Such frequencies have selected ~ones that provide the marker with signal identity. A de~ecting means is arranged to detect magnetic field variations at selected tones of the harmonics produced in the vicinity of the interrogation zone by the presence of the marker therewithin. The marker retains its signal identity after being flexed or bent. ~s a result, the theft detection system is more reliable in operation than system wherein signal degradation is effected by bending or flexing of the marker. Further, ~he marker contains no costly and strategic metals such as nickel or cobalt.
BRIE~ DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood and further advantages will become apparent when reference is made to the following detailed description of the preferred embodiment of the invention and the accompanying drawings in which:
FIG~ 1 is a block diagram of a magnetic theft detection system incorporating the present invention;
FIG. 2 i~ a diagrammatic illustration of a typical 6tores installation of the system of Fig. l;
: 3 FIG. 3 is an isomeric view of a marker adapted for use in the system of Fig. l;
FIG. 4 is an isomeric view of a desensitizable marker adapted for use in the system of Fig. l; and FIG. 5 is a schematic electrical diagram of a harmonic signal amplitude ~est apparatus used to measure the signal retention capability of the amorphous ferro-magnetic metal marker of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figures 1 and 2 of the drawings, there is shown a magnetic theft detection system 10 responsive to the presence of an article within an interrogation zone. The system 10 has means for de-fining an interrogation zone 12. A field generating means 14 is provided for generating a magnetic field within the interrogation zone 12. A marker 16 is secured to an article 19 appointed for passage through the interrogation zone 12. The marker comprises an elongated, ductile strip 18 of amorphous, ferromagnetic metal having a composition consisting essentially of ula FeacrbccpdMoecufBgsih where ~a~ ranges from 30 about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom ~, "e" ranges from abou~ 0--2 atom %, "f" ranges from about 0~1 atom %, llgll ranges from about 0-4 atom % and "i" ranges from about 0-2 atom ~, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/lc~d~g+h)] is less than about 0~84.
The marker is capable of producing magnetic fields at f~equencies which are harmonics of the frequency of an incident field. Such frequencies have selected tones that provide the marker with signal identity. A detecting means 20 is arranged to detect magnetic field variations at selected ~ones of the harmonics produced in the vicinity of the interrogation zone 12 by the presence of marker 16 therewithin.
Typically, the system 10 includes a pair of coil units 22, 24 disposed on opposing sides of a path ! 10 leading to the exit 26 of a store. Detection circuitry, including an alarm 28, is housed within a cabinet 30 located near the exit 26. Articles of merchandise 19 such as wearing apparel, appliances, books and the like are di~played within the store. Each of the artlcles 19 has secured thereto a marker 16 constructed in accordance with the present invention. The marker 16 includes an elongated, ductile amorphous ferromagnetic strip 18 that is normally in an activated mode. When marker 16 is in the activated mode, placement of an article 19 between coil units 22 and 24 of interrogation zone 12 will cause an alarm to be emitted from cabinet 30. In this manner, the system 10 prevents unauthorized - removal of articles of merchandise 19 from the store.
Disposed on a checkout counter near cash reg-ister 36 is a deactivator system 38. The latter is electrically connected to cash register 36 by wire 40.
Articles 19 that have been properly paid for are placed within an aperture 42 of deactivation system 38, where~
upon a magnetic field similar ~o that produced by coil units 22 and 24 of interrogation zone 12 is applied to marker 16. The deactivation system 38 has detection circuitry adapted to activate a gaussing circuit in response to harmonic signals generated by marker 16.
The gaussing circuit applies to marker 16 a high mag-netic field that places the marker 16 in a deactivated mode. The article 19 carrying the deactivated marker 16 may then be carried through interrogation zone 12 without triggering the alarm 2B in cabinet 30O
- s -The theft detection system circuitry with which the marker 16 is associated can be any system capable of (1) generating within an interrogation zone an incident magnetic field, and (2) detecting magnetic field variations at 6elected harmonic frequencies pro-duced in the vicinity of the interrogation zone by the presence of the marker therewithin. 5uch systems typically include means for transmitting a varying ¦, electrical current from an oscillator and amplifier through conductive coils that form a frame antenna capable of developing a varying magnetic field. An example of such antenna arrangement is disclosed in French Patent 763,681, published May 4, 1934, which description is incorporated herein by reference thereto.
lS In accordance with a preferred embodiment of the invention, an amorphous ferromagnetic metal marker is provided. The marker is in the form of an elongated/
ductile s~rip having a composition consisting essential-ly of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63~81 atom ~, "b" ranges from about 0-10 atom %,"c" ranges from about 11-16 atom ~, "d" range~ from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom ~, "g" ranges Erom about 0-4 atom % and "i" ranges from about 0-2 atom ~, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom ~ and the fraction [c/(c+d+g+h)] is less than about 0.84.
The marker is capable of producing ma~netic fields at frequencies which are harmonics of the frequency of an incident field Examples of amorphous ferromagnetic marker compositions within the scope of the inve~tion are set forth in Table I below:
~ Ei9~
TABLE X
COMPOSITION PERCENT
Fe Cr Mc~ C~ C P B Si 1 Atom % 73025 6 0.25 0 13 7 0.5 0 Weight % 85.14 6.49 0.50 0 3.25 4.51 0.11 0 2 Atam % 73.25 6 0.25 0 15 5 0.5 0 Weight ~ 85.81 6.55 0.50 O 3.78 3.25 0.11 O
Systems employed to prevent ~heft of articles generally comprise a marker element secured to an object to ~e detec~ed and instruments adapted to sense a signal produced by the marker upon passage thereof through an interrogation ~one~
One of the major problems with such theft detection systems is the low signal level produced by the marker. This limits the sensitivity and reliability of the theft detection system~ Ancther problem is the dificulty of preventing degradation of the maker signal.
If the marker is broken or bent, the signal can be lost or altered in a manner that impairs its identifying 6~6 characteristics. Such bending or breaking of the marker can occur inadvertently during manufacture of the marker and subsequent handling of merchandise by employees and ~ustomers, or purposely in connection with attempted theft of goods. The present invention is directed to overcoming the foregoing problems.
SUMMARY OF THE INVENTION
.
BrieEly stated, the invention provides an amorphous ferromagnetic metal marker capable of produc-ing identifying signal characteristics in the presenceof an applied magnetic field. The marker comprises an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula FeaCrbccPdMoecufB9sih where "a" ranges from about 63-81 a~om %, "b" ranges from about 0-10 atom ~, ~c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e~ ranges from about 0-2 atom ~, "f " ranges from about 0-1 atom ~, 119~ ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c~d+g~h) ranges from 19-24 atom % and the fraction [c/(c~d-~g+h)] is less than about 0.84.
The marker is capable of producing magnetic fields at fre~uencies which are harmonics of the frequency of an incident field. Such frequencies have selected ~ones that provide the marker with signal identity. A de~ecting means is arranged to detect magnetic field variations at selected tones of the harmonics produced in the vicinity of the interrogation zone by the presence of the marker therewithin. The marker retains its signal identity after being flexed or bent. ~s a result, the theft detection system is more reliable in operation than system wherein signal degradation is effected by bending or flexing of the marker. Further, ~he marker contains no costly and strategic metals such as nickel or cobalt.
BRIE~ DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood and further advantages will become apparent when reference is made to the following detailed description of the preferred embodiment of the invention and the accompanying drawings in which:
FIG~ 1 is a block diagram of a magnetic theft detection system incorporating the present invention;
FIG. 2 i~ a diagrammatic illustration of a typical 6tores installation of the system of Fig. l;
: 3 FIG. 3 is an isomeric view of a marker adapted for use in the system of Fig. l;
FIG. 4 is an isomeric view of a desensitizable marker adapted for use in the system of Fig. l; and FIG. 5 is a schematic electrical diagram of a harmonic signal amplitude ~est apparatus used to measure the signal retention capability of the amorphous ferro-magnetic metal marker of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figures 1 and 2 of the drawings, there is shown a magnetic theft detection system 10 responsive to the presence of an article within an interrogation zone. The system 10 has means for de-fining an interrogation zone 12. A field generating means 14 is provided for generating a magnetic field within the interrogation zone 12. A marker 16 is secured to an article 19 appointed for passage through the interrogation zone 12. The marker comprises an elongated, ductile strip 18 of amorphous, ferromagnetic metal having a composition consisting essentially of ula FeacrbccpdMoecufBgsih where ~a~ ranges from 30 about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom ~, "e" ranges from abou~ 0--2 atom %, "f" ranges from about 0~1 atom %, llgll ranges from about 0-4 atom % and "i" ranges from about 0-2 atom ~, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/lc~d~g+h)] is less than about 0~84.
The marker is capable of producing magnetic fields at f~equencies which are harmonics of the frequency of an incident field. Such frequencies have selected tones that provide the marker with signal identity. A detecting means 20 is arranged to detect magnetic field variations at selected ~ones of the harmonics produced in the vicinity of the interrogation zone 12 by the presence of marker 16 therewithin.
Typically, the system 10 includes a pair of coil units 22, 24 disposed on opposing sides of a path ! 10 leading to the exit 26 of a store. Detection circuitry, including an alarm 28, is housed within a cabinet 30 located near the exit 26. Articles of merchandise 19 such as wearing apparel, appliances, books and the like are di~played within the store. Each of the artlcles 19 has secured thereto a marker 16 constructed in accordance with the present invention. The marker 16 includes an elongated, ductile amorphous ferromagnetic strip 18 that is normally in an activated mode. When marker 16 is in the activated mode, placement of an article 19 between coil units 22 and 24 of interrogation zone 12 will cause an alarm to be emitted from cabinet 30. In this manner, the system 10 prevents unauthorized - removal of articles of merchandise 19 from the store.
Disposed on a checkout counter near cash reg-ister 36 is a deactivator system 38. The latter is electrically connected to cash register 36 by wire 40.
Articles 19 that have been properly paid for are placed within an aperture 42 of deactivation system 38, where~
upon a magnetic field similar ~o that produced by coil units 22 and 24 of interrogation zone 12 is applied to marker 16. The deactivation system 38 has detection circuitry adapted to activate a gaussing circuit in response to harmonic signals generated by marker 16.
The gaussing circuit applies to marker 16 a high mag-netic field that places the marker 16 in a deactivated mode. The article 19 carrying the deactivated marker 16 may then be carried through interrogation zone 12 without triggering the alarm 2B in cabinet 30O
- s -The theft detection system circuitry with which the marker 16 is associated can be any system capable of (1) generating within an interrogation zone an incident magnetic field, and (2) detecting magnetic field variations at 6elected harmonic frequencies pro-duced in the vicinity of the interrogation zone by the presence of the marker therewithin. 5uch systems typically include means for transmitting a varying ¦, electrical current from an oscillator and amplifier through conductive coils that form a frame antenna capable of developing a varying magnetic field. An example of such antenna arrangement is disclosed in French Patent 763,681, published May 4, 1934, which description is incorporated herein by reference thereto.
lS In accordance with a preferred embodiment of the invention, an amorphous ferromagnetic metal marker is provided. The marker is in the form of an elongated/
ductile s~rip having a composition consisting essential-ly of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63~81 atom ~, "b" ranges from about 0-10 atom %,"c" ranges from about 11-16 atom ~, "d" range~ from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom ~, "g" ranges Erom about 0-4 atom % and "i" ranges from about 0-2 atom ~, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom ~ and the fraction [c/(c+d+g+h)] is less than about 0.84.
The marker is capable of producing ma~netic fields at frequencies which are harmonics of the frequency of an incident field Examples of amorphous ferromagnetic marker compositions within the scope of the inve~tion are set forth in Table I below:
~ Ei9~
TABLE X
COMPOSITION PERCENT
Fe Cr Mc~ C~ C P B Si 1 Atom % 73025 6 0.25 0 13 7 0.5 0 Weight % 85.14 6.49 0.50 0 3.25 4.51 0.11 0 2 Atam % 73.25 6 0.25 0 15 5 0.5 0 Weight ~ 85.81 6.55 0.50 O 3.78 3.25 0.11 O
3 ~tom % 71.25 ~ 0.25 O 13 7 0.5 O
Weight % 82.94 8.67 OD50 O 3.25 4.52 0.11 O
Weight % 82.94 8.67 OD50 O 3.25 4.52 0.11 O
4 Atc~n % 71.25 8 0~25 0 15 5 0.5 0 ~eight % 83.60 8.74 0.50 O 3.78 3.25 0.11 O
Atcm % 73.5 6 1.0 0 13 7 0.5 0 W~ight % 83.92 6.38 1.96 0 3.19 4.43 0.11 0 6 Atom % 73.5 6 1.0 0 15 5 0.5 0 W~ight % 84.58 6.43 1.98 0 3.71 3.19 0.11 0 7 Atom % 70.5 8 1.0 0 13 7 0.5 0 Weight % 81.56 8.62 1.99 0 3.23 4.49 0.11 0 8 ~tom % 70.5 8 1.0 O 15 5 0.5 O
We.ight % 82.20 8.69 2.00 O 3.76 3.23 0.11 O
9 Atan % 79 0 0 0 13 4 2 2 Wei~ht ~ 92.5 O O O 3.27 2.60 0.45 1.8 - 10 Atom % 73.15 6 0.25 0.1 15 5 005 0 Weight % 85.68 6.54 0.50 0.13 3.78 3.25 0.11 O
11 Atcm % 71.0 10 0 0 14 4.5 0.5 0 Weight % 82.64 .10.84 0 0 3.50 2.90 0~11 O
12 Atar % 71.5 6 2 0 15 5 0.5 0 Weight % 82055 6.45 3.97 O 3.72 3.20 0.11 0 l 30 Examples of amorphous metallic alloys that have been found suitable for use as a magnetic theft detection system marker but which are outside the scope of this invention and are set Eorth in Table II below:
TABLE II
COMPOSIT _N PERCENT
Fe Co Ni Mo _ P Si Fe-Ni-Mo-B Atom % 40 - 40 2 18 - -We.ight% 45 - 47 4 4 Fe-Ni-P-B Atom % 39.2 - 40.2 - 6.2 14.4 -Weight % 43.23 - 46.62 - 1.32 8.83 -Fe-Ni-B Atom % 40 - 40 - 20 Weight % 46.6 - 48.9 - 4.5 -Fe-B Atom % 79.7 - - - 20.3 - -Weight % 95.38 - - - 4.62 -Fe-Mo-B Atom % 77.5 - - 2.520 Weight % 90.47 - - 5.01 4.52 -Co-FeiMo- Aton % 5.5 67.5 - 2 12 - 13 B-Si Weight % 6.19 80 - 3.86 2.61 - 7.34 Examples of amorphou.s me*al alloys that have been found unsuitable for use as a magnetic theft detec-tion system are set forth in Table III below:
'l~i' TABLE III
Composition Percent Example 1 Example 2 Ni Atom % 71.67 Ni Atom % 65.63 Weight % 84.40 Weight % 76.97 Cr Atom % 5.75 Cr Atom % 11~55 Weight % 6 Weight % 12.0 B Atom ~ 12.68 B Atom % 11.58 Weight % 2.75 Weight % 2.5 Si Atom ~ 7.10 Si Atom % 7.13 , 10Weight % 4 Weight % 4 Fe Atom ~ 2.23 Fe Atom % 3.14 Weight ~ 2.5 Weight % 3.5 C Atom % .25 C Atom ~ .12 Weight % .06 Weight % .03 P Atom % .032 P Atom %
Weight ~ .02 Weight %
S Atom % .031 S Atom %
Weight % .02 Weight ~ -Al Atom % .093 Al Atom %
Weight % .05 Weight %
- Ti Atom ~ .052 Ti Atom %
Weight % .05 Weight %
Zr Atom ~ .027 Zr Atom %
Weight % .05 Weight ~ -Co Atom % .085 Co Atom % .85 Weight ~ .1 Weight % 1.0 The amorphous ferromagnetic metal marker of the invention is prepared by cooling a melt of the desired composition at a rate of at least about 105C/
sec, employing metal alloy quenching techniques well-known to the glassy metal alloy art; see, e.g., U.S.
Patent 3,856,513 to Chen et al. The purity of all compositions is that found in normal commercial practice.
A variety of techniques are available for fabricating continuous ribbon, wire, sheet, etc. Typi-cally, a particular composition is selected, powders or granules of the requisite elements in the desired por-tions are melted and homogeni~ed, and the molten alloy is xapidly quenched on a chill surface, such as a rapidly rotating metal cylinder, a rapidly moving metal belt or the like.
Under these quenching conditions, a meta-stable, homogeneous, ductile material is obtained. I'he metastable material may be glassy, in which case there is no long-range order. X-ray diffraction patterns of glassy metal alloys show only a diffuse halo, similar to that observed for inorganic oxide glasses. Such glassy alloys must be at least 50~ glassy to be suffi-ciently ductile to permit subsequent handling, such as stamping complex marker shapes from ribbons of the alloys without degradation of the marker's signal iden-tity. Preferably, the glassy metal marker must be at least 80% glassy to attain superior ductility.
The metastable phase may also be a solid solu-tion of the constituent elements. In the case of themarker of the invention, such metastable, solid solution phases are not ordinarily produced under conventional processing techniques employed in the art of fabricating crystalline alloysO X-ray diffraction patterns of the solid solution alloys show the sharp diffraction peaks characteristic of crystalline alloys, with some broaden-ing of the peaks due to desired fine-grained size of crystallites. Such metastable materials are also duc-tile when produced under the conditions described above.
The marker of the invention is advantageously produced in foil (or ribbon) form, and may be used in theft detection applications as cast, whether the material is glassy or a solid solution. Alternatively, foils of glassy metal alloys may be heat treated to obtain a crystallilne phase, preferably fine-grained, in order to promote longer die life when stamping of com-plex marker shapes is contemplated. Markers having par-tially crystalline, partially glassy phases are parti-cularly s~ited to be desensitized by a deactivation system 38 of the type shown in Fig. 2~ Totally amor-phous ferromagnetic marker strips can be provided with one or more small magnetiæable elements 44. Such ele-ments 44 are made of crystalline regions of ferromagne-tic material having a higher coercivity than thatpossessed by the strip 18. Moreover, totally amorpho~s marker strip can be spot welded, heat treated with coherent or incoherent radiation, charged particle beams, directed flames, heated wires or the like to provide the strip with magnetizable elements 44 that are integral therewith. Further, such elements 44 can be integrated with strip 18 during casting thereof by selectively altering the cooling rate of the strip 18.
Cooling rate alteration can be effected by quenching the alloy on a chill surface that is slotted or contains hea~ed portions adapted to allow partial crystallazation during quenching. Alternatively, alloys can be selected that partially crystallize during casting. The ribbon thickness can be varied during casting to produce crystalline regions over a portion of strip 18.
Upon permanent magnetization of the elements 44, their permeability is s~bstantially decreased~ The magnetic fields associated with such magnetization bias the strip 18 and thereby alter its response to the mag-netic field extant in the interrogation zone 12. In the activated mode, the strip 18 is unbiased with the result that the high permeability state of strip 1~ has a pro-nounced effect upon the magnetic field applied thereto by field generating means 14. The marker 16 is deacti-vated by magnetizing elements 44 to decrease the effec-tive permeability of the strip 18. The reduction in per~neability significantly decreases the effect of the marker 16 on the magnetic field, whereby the marker 16 loses its signal identity (e.g., marker 16 is less able to distort or reshape the field). Under these condi-tions, the protected articles 19 can pass through interrogation zone 12 without triggering alarm 28.
The amorphous ferr~magnetic mar~er of the present invention is e~ceedingly ductile. B~ d~ctile is meant that the strip 18 can be bent to a bend diameter less than 35 mils. The term ~'bend diameter" is defined as D=S-2T, where D is the bend diame~er in mils, S is the minimum spacing between micrometer anvils within which a ribbon may be looped without breakage and T is the ribbon thickness. Such bending of the marker pro-duces little or no degradation in magnetic harmonics generated by the marker upon application of the inter-rogating magnetic field thereto. As a result, the marker retains its signal identity despite being flexed or bent during (1) manufacture (e7g., cutting, stamping or otherwise forming the strip 18 into the desired length and configuration) and, optionally, applying hard magnetic chips thereto to produce an on/off marker, (2) application of the marker 16 to the protected articles 19, (3) handling of the articles 19 by employees and customers and (4) attempts at signal destruction designed to circumvent the system 10.
Generation of harmonics by marker 16 is caused by nonlinear magnetization response of the marker 16 to an incident magnetic field. High permeability - low coercive force material such as Permalloy, Supermalloy and the like produce such nonlinear response in an amplitude region of the incident field wherein the mag-netic field strength is sufficiently great to saturate the material. ~morphous ferromagnetic materials have nonlinear magneti~ation response over a significantly greater amplitude region ranging from relatively low magnetic fields to higher magnetic field values approaching saturation. The additional amplitude region of nonlinear magnetization response possessed by amorphous ferromagnetic materials increases the magni-tude of harmonics generated by, and hence the signalstrength of, marker 16, This feature permits use of lower magnetic fields, eliminates false alarms and improves detection reliability of the system 10.
The following examples are presented to pro-vide a more complete understanding of the in~ention.The specific techniques, conditions, materials and reported data set forth to illustrate the principles and practice of the invention are exemplary and should not be construed as limiting the scope of the invention.
EXAMPLE I
In order to demonstrate quantitatively the improved harmonic generation of the amorphous antipil-ferage marker of the invention, elongated strips corn-posed of ferromagnetic amorphous and crystalline materials were prepared. The strips ~7ere evaluated to determine their signal strength before and after flexure using a harmonic signal amplitute test apparatus 100.
A schematic electrical diagram of the test apparatus 100 is shown in Fig. 5. The apparatus 100 had an oscil-lator generator 101 for generating a sinusoidal signal at a frequency of 2.5 KHz. Oscillator generator 101 drove a power amplifier 102 connected in series with an applied field coil 104 through a sampling resistor 106.
The current output of amplifier 102 was adjusted to produce a magnetic field of 1.0 Oersted within applied field coil 104. The voltage, V, across sampling resistor 106 was measured by digital voltmeter 100, and the current, I, in the coil 2 was calculated from Ohms Law, I = V/R. A dc 0.41 Oersted field was used to bias the sample and the coil 104 were oriented perpendicular to the earth's magnetic fieldO Applied field coil 104 was constructed of 121 twins of closely wrapped, #14 AWG. insulated copper wire. Coil 104 had an inside diameter of 5.1 cm and was 45.7 cm long. Pick up coil 112 was constructed of 540 turns of closely wrapped ~26 AWG. insulated copper wire. The coil 112 had an inside diameter of 1.9 cm and was 7.6 cm long. A sample marker 110 was placed in pick-up coil 11~, which is coaxially disposed inside the applied field coil 104. The voltage generated by the pick-up coil 112 was fed into ~unable wave analizer 114 comprised of a frequency selectable band pass filter and a c voltmeter. The band pass filter was tuned to 15 KHz, an integer multiple of the drive frequency generated by the oscillator generator 101. The amplitude of harmonic response by the sample marker 110 was measured with the wave analyzer 114 and indicated by an analogue display. A dual channel oscilloscope 116 was also used to graphically display the applied and reradiated signal.
The harmonic generation test apparatus 100 was used to test marker samples composed of material identi-fied in Table IV. Each of the samples, numbered 1-15 in Table IV was 10.2 cm long. The samples were placed inside pickup coil 112 and applied field coil 104 and the amplitude of harmonic response for each sample 110 was obse rve d.
TABLE IV
Sample No Fe Ni Cr Mo Cu C P B Si _ Alloys of ~his Invention 1 73O25 0 6 0.25 0 13 7 0.5 0 2 73.25 0 6 ~.25 0 15 5 0.5 0 3 71.25 0 8 0.25 0 13 7 0.5 0 4 71.25 0 8 0.25 0 15 5 0.5 0 73.5 0 6 1.0 0 13 7 0.5 0 6 73.5 0 6 1.0 0 15 5 0.5 0 7 70.5 0 8 1.0 0 13 7 0.5 0 8 70.5 0 8 1.0 0 15 5 0.5 0 Marker Dimensions Sample Length Width THK Harmonic Signal No. Structure cm cm mV NV/m3 r Alloys of this Invention 1 Amorphous 10.2 0.041 33 46.7 33.8 2 Amorphous 10.2 0.038 25 41.7 43.0 3 Amorphous 10.2 0.036 31 25.0 22.0 4 Amorphous 10.2 0.046 33 43.3 28.0 ~morphous 10.2 0.038 28 31.3 28.8 6 Amorphous 10.2 0.036 38 31.7 22.7 7 Amorphous 10.2 0~036 36 28.3 21.4 8 Amorphous 10.2 0O043 36 35.0 22.2 Sample No Fe Ni Cr Mo Cu C P B Si _lloys Not of This Inventio ~0 0 2 0 0 0 18 0 11 40 ~0 0 2 0 0 0 18 0 Marker Dimensions SampleLength Width THK Harmonic Signal No. Structure cm cm mV MV/m3 _ Alloys Not of This Invention 109 Amorphous 10.2 0.051 25 28.3 21.8 10 Amorphous 10.2 0.051 31 20.3 12.6 11 Amorphous 10.2 0.178 58 167 15.8 As shown by the data reported in Table IV, the samples composed of the amorphous ferromagnetic materi-als of this invention showed equal or improved harmonic amplitude per unit volume of sample compared to the control samples. Thus sample No. 2 of Table IV of composition Fe 73.25, Cr 6, Mo 0.25, C 15, P 5, B 0.5 showed a harmonic signal of 43.0 megavolts per cubic 20 meter ~MV/m3) of sample compound to 12.6 to 21.8 MV/m3 for the control samples. It should be further noted that the alloys of this invention contained no content of strategic and costly metals such as nickel or cobalt other than in concentrations which normally would be present as impurities.
The samples of Table IV were helically woundaround a 5-mm diameter mandrel to produce a degraded condition, straightened and placed in pickup coil 112 and applied field coil 104, as before, to observe the amplitude of harmonic response produced thereby. All samples retained in excess of 90% of their original har-monic amplitude after flexing and bendingO
Having thus described the invention in rather full detail, it will be understood that these details need not be strictly adhered to but that further changes and modifications may suggest themselves to one having ordinary skill in the art, all falling within the scope of the invention as defined by the subjoined claims.
Atcm % 73.5 6 1.0 0 13 7 0.5 0 W~ight % 83.92 6.38 1.96 0 3.19 4.43 0.11 0 6 Atom % 73.5 6 1.0 0 15 5 0.5 0 W~ight % 84.58 6.43 1.98 0 3.71 3.19 0.11 0 7 Atom % 70.5 8 1.0 0 13 7 0.5 0 Weight % 81.56 8.62 1.99 0 3.23 4.49 0.11 0 8 ~tom % 70.5 8 1.0 O 15 5 0.5 O
We.ight % 82.20 8.69 2.00 O 3.76 3.23 0.11 O
9 Atan % 79 0 0 0 13 4 2 2 Wei~ht ~ 92.5 O O O 3.27 2.60 0.45 1.8 - 10 Atom % 73.15 6 0.25 0.1 15 5 005 0 Weight % 85.68 6.54 0.50 0.13 3.78 3.25 0.11 O
11 Atcm % 71.0 10 0 0 14 4.5 0.5 0 Weight % 82.64 .10.84 0 0 3.50 2.90 0~11 O
12 Atar % 71.5 6 2 0 15 5 0.5 0 Weight % 82055 6.45 3.97 O 3.72 3.20 0.11 0 l 30 Examples of amorphous metallic alloys that have been found suitable for use as a magnetic theft detection system marker but which are outside the scope of this invention and are set Eorth in Table II below:
TABLE II
COMPOSIT _N PERCENT
Fe Co Ni Mo _ P Si Fe-Ni-Mo-B Atom % 40 - 40 2 18 - -We.ight% 45 - 47 4 4 Fe-Ni-P-B Atom % 39.2 - 40.2 - 6.2 14.4 -Weight % 43.23 - 46.62 - 1.32 8.83 -Fe-Ni-B Atom % 40 - 40 - 20 Weight % 46.6 - 48.9 - 4.5 -Fe-B Atom % 79.7 - - - 20.3 - -Weight % 95.38 - - - 4.62 -Fe-Mo-B Atom % 77.5 - - 2.520 Weight % 90.47 - - 5.01 4.52 -Co-FeiMo- Aton % 5.5 67.5 - 2 12 - 13 B-Si Weight % 6.19 80 - 3.86 2.61 - 7.34 Examples of amorphou.s me*al alloys that have been found unsuitable for use as a magnetic theft detec-tion system are set forth in Table III below:
'l~i' TABLE III
Composition Percent Example 1 Example 2 Ni Atom % 71.67 Ni Atom % 65.63 Weight % 84.40 Weight % 76.97 Cr Atom % 5.75 Cr Atom % 11~55 Weight % 6 Weight % 12.0 B Atom ~ 12.68 B Atom % 11.58 Weight % 2.75 Weight % 2.5 Si Atom ~ 7.10 Si Atom % 7.13 , 10Weight % 4 Weight % 4 Fe Atom ~ 2.23 Fe Atom % 3.14 Weight ~ 2.5 Weight % 3.5 C Atom % .25 C Atom ~ .12 Weight % .06 Weight % .03 P Atom % .032 P Atom %
Weight ~ .02 Weight %
S Atom % .031 S Atom %
Weight % .02 Weight ~ -Al Atom % .093 Al Atom %
Weight % .05 Weight %
- Ti Atom ~ .052 Ti Atom %
Weight % .05 Weight %
Zr Atom ~ .027 Zr Atom %
Weight % .05 Weight ~ -Co Atom % .085 Co Atom % .85 Weight ~ .1 Weight % 1.0 The amorphous ferromagnetic metal marker of the invention is prepared by cooling a melt of the desired composition at a rate of at least about 105C/
sec, employing metal alloy quenching techniques well-known to the glassy metal alloy art; see, e.g., U.S.
Patent 3,856,513 to Chen et al. The purity of all compositions is that found in normal commercial practice.
A variety of techniques are available for fabricating continuous ribbon, wire, sheet, etc. Typi-cally, a particular composition is selected, powders or granules of the requisite elements in the desired por-tions are melted and homogeni~ed, and the molten alloy is xapidly quenched on a chill surface, such as a rapidly rotating metal cylinder, a rapidly moving metal belt or the like.
Under these quenching conditions, a meta-stable, homogeneous, ductile material is obtained. I'he metastable material may be glassy, in which case there is no long-range order. X-ray diffraction patterns of glassy metal alloys show only a diffuse halo, similar to that observed for inorganic oxide glasses. Such glassy alloys must be at least 50~ glassy to be suffi-ciently ductile to permit subsequent handling, such as stamping complex marker shapes from ribbons of the alloys without degradation of the marker's signal iden-tity. Preferably, the glassy metal marker must be at least 80% glassy to attain superior ductility.
The metastable phase may also be a solid solu-tion of the constituent elements. In the case of themarker of the invention, such metastable, solid solution phases are not ordinarily produced under conventional processing techniques employed in the art of fabricating crystalline alloysO X-ray diffraction patterns of the solid solution alloys show the sharp diffraction peaks characteristic of crystalline alloys, with some broaden-ing of the peaks due to desired fine-grained size of crystallites. Such metastable materials are also duc-tile when produced under the conditions described above.
The marker of the invention is advantageously produced in foil (or ribbon) form, and may be used in theft detection applications as cast, whether the material is glassy or a solid solution. Alternatively, foils of glassy metal alloys may be heat treated to obtain a crystallilne phase, preferably fine-grained, in order to promote longer die life when stamping of com-plex marker shapes is contemplated. Markers having par-tially crystalline, partially glassy phases are parti-cularly s~ited to be desensitized by a deactivation system 38 of the type shown in Fig. 2~ Totally amor-phous ferromagnetic marker strips can be provided with one or more small magnetiæable elements 44. Such ele-ments 44 are made of crystalline regions of ferromagne-tic material having a higher coercivity than thatpossessed by the strip 18. Moreover, totally amorpho~s marker strip can be spot welded, heat treated with coherent or incoherent radiation, charged particle beams, directed flames, heated wires or the like to provide the strip with magnetizable elements 44 that are integral therewith. Further, such elements 44 can be integrated with strip 18 during casting thereof by selectively altering the cooling rate of the strip 18.
Cooling rate alteration can be effected by quenching the alloy on a chill surface that is slotted or contains hea~ed portions adapted to allow partial crystallazation during quenching. Alternatively, alloys can be selected that partially crystallize during casting. The ribbon thickness can be varied during casting to produce crystalline regions over a portion of strip 18.
Upon permanent magnetization of the elements 44, their permeability is s~bstantially decreased~ The magnetic fields associated with such magnetization bias the strip 18 and thereby alter its response to the mag-netic field extant in the interrogation zone 12. In the activated mode, the strip 18 is unbiased with the result that the high permeability state of strip 1~ has a pro-nounced effect upon the magnetic field applied thereto by field generating means 14. The marker 16 is deacti-vated by magnetizing elements 44 to decrease the effec-tive permeability of the strip 18. The reduction in per~neability significantly decreases the effect of the marker 16 on the magnetic field, whereby the marker 16 loses its signal identity (e.g., marker 16 is less able to distort or reshape the field). Under these condi-tions, the protected articles 19 can pass through interrogation zone 12 without triggering alarm 28.
The amorphous ferr~magnetic mar~er of the present invention is e~ceedingly ductile. B~ d~ctile is meant that the strip 18 can be bent to a bend diameter less than 35 mils. The term ~'bend diameter" is defined as D=S-2T, where D is the bend diame~er in mils, S is the minimum spacing between micrometer anvils within which a ribbon may be looped without breakage and T is the ribbon thickness. Such bending of the marker pro-duces little or no degradation in magnetic harmonics generated by the marker upon application of the inter-rogating magnetic field thereto. As a result, the marker retains its signal identity despite being flexed or bent during (1) manufacture (e7g., cutting, stamping or otherwise forming the strip 18 into the desired length and configuration) and, optionally, applying hard magnetic chips thereto to produce an on/off marker, (2) application of the marker 16 to the protected articles 19, (3) handling of the articles 19 by employees and customers and (4) attempts at signal destruction designed to circumvent the system 10.
Generation of harmonics by marker 16 is caused by nonlinear magnetization response of the marker 16 to an incident magnetic field. High permeability - low coercive force material such as Permalloy, Supermalloy and the like produce such nonlinear response in an amplitude region of the incident field wherein the mag-netic field strength is sufficiently great to saturate the material. ~morphous ferromagnetic materials have nonlinear magneti~ation response over a significantly greater amplitude region ranging from relatively low magnetic fields to higher magnetic field values approaching saturation. The additional amplitude region of nonlinear magnetization response possessed by amorphous ferromagnetic materials increases the magni-tude of harmonics generated by, and hence the signalstrength of, marker 16, This feature permits use of lower magnetic fields, eliminates false alarms and improves detection reliability of the system 10.
The following examples are presented to pro-vide a more complete understanding of the in~ention.The specific techniques, conditions, materials and reported data set forth to illustrate the principles and practice of the invention are exemplary and should not be construed as limiting the scope of the invention.
EXAMPLE I
In order to demonstrate quantitatively the improved harmonic generation of the amorphous antipil-ferage marker of the invention, elongated strips corn-posed of ferromagnetic amorphous and crystalline materials were prepared. The strips ~7ere evaluated to determine their signal strength before and after flexure using a harmonic signal amplitute test apparatus 100.
A schematic electrical diagram of the test apparatus 100 is shown in Fig. 5. The apparatus 100 had an oscil-lator generator 101 for generating a sinusoidal signal at a frequency of 2.5 KHz. Oscillator generator 101 drove a power amplifier 102 connected in series with an applied field coil 104 through a sampling resistor 106.
The current output of amplifier 102 was adjusted to produce a magnetic field of 1.0 Oersted within applied field coil 104. The voltage, V, across sampling resistor 106 was measured by digital voltmeter 100, and the current, I, in the coil 2 was calculated from Ohms Law, I = V/R. A dc 0.41 Oersted field was used to bias the sample and the coil 104 were oriented perpendicular to the earth's magnetic fieldO Applied field coil 104 was constructed of 121 twins of closely wrapped, #14 AWG. insulated copper wire. Coil 104 had an inside diameter of 5.1 cm and was 45.7 cm long. Pick up coil 112 was constructed of 540 turns of closely wrapped ~26 AWG. insulated copper wire. The coil 112 had an inside diameter of 1.9 cm and was 7.6 cm long. A sample marker 110 was placed in pick-up coil 11~, which is coaxially disposed inside the applied field coil 104. The voltage generated by the pick-up coil 112 was fed into ~unable wave analizer 114 comprised of a frequency selectable band pass filter and a c voltmeter. The band pass filter was tuned to 15 KHz, an integer multiple of the drive frequency generated by the oscillator generator 101. The amplitude of harmonic response by the sample marker 110 was measured with the wave analyzer 114 and indicated by an analogue display. A dual channel oscilloscope 116 was also used to graphically display the applied and reradiated signal.
The harmonic generation test apparatus 100 was used to test marker samples composed of material identi-fied in Table IV. Each of the samples, numbered 1-15 in Table IV was 10.2 cm long. The samples were placed inside pickup coil 112 and applied field coil 104 and the amplitude of harmonic response for each sample 110 was obse rve d.
TABLE IV
Sample No Fe Ni Cr Mo Cu C P B Si _ Alloys of ~his Invention 1 73O25 0 6 0.25 0 13 7 0.5 0 2 73.25 0 6 ~.25 0 15 5 0.5 0 3 71.25 0 8 0.25 0 13 7 0.5 0 4 71.25 0 8 0.25 0 15 5 0.5 0 73.5 0 6 1.0 0 13 7 0.5 0 6 73.5 0 6 1.0 0 15 5 0.5 0 7 70.5 0 8 1.0 0 13 7 0.5 0 8 70.5 0 8 1.0 0 15 5 0.5 0 Marker Dimensions Sample Length Width THK Harmonic Signal No. Structure cm cm mV NV/m3 r Alloys of this Invention 1 Amorphous 10.2 0.041 33 46.7 33.8 2 Amorphous 10.2 0.038 25 41.7 43.0 3 Amorphous 10.2 0.036 31 25.0 22.0 4 Amorphous 10.2 0.046 33 43.3 28.0 ~morphous 10.2 0.038 28 31.3 28.8 6 Amorphous 10.2 0.036 38 31.7 22.7 7 Amorphous 10.2 0~036 36 28.3 21.4 8 Amorphous 10.2 0O043 36 35.0 22.2 Sample No Fe Ni Cr Mo Cu C P B Si _lloys Not of This Inventio ~0 0 2 0 0 0 18 0 11 40 ~0 0 2 0 0 0 18 0 Marker Dimensions SampleLength Width THK Harmonic Signal No. Structure cm cm mV MV/m3 _ Alloys Not of This Invention 109 Amorphous 10.2 0.051 25 28.3 21.8 10 Amorphous 10.2 0.051 31 20.3 12.6 11 Amorphous 10.2 0.178 58 167 15.8 As shown by the data reported in Table IV, the samples composed of the amorphous ferromagnetic materi-als of this invention showed equal or improved harmonic amplitude per unit volume of sample compared to the control samples. Thus sample No. 2 of Table IV of composition Fe 73.25, Cr 6, Mo 0.25, C 15, P 5, B 0.5 showed a harmonic signal of 43.0 megavolts per cubic 20 meter ~MV/m3) of sample compound to 12.6 to 21.8 MV/m3 for the control samples. It should be further noted that the alloys of this invention contained no content of strategic and costly metals such as nickel or cobalt other than in concentrations which normally would be present as impurities.
The samples of Table IV were helically woundaround a 5-mm diameter mandrel to produce a degraded condition, straightened and placed in pickup coil 112 and applied field coil 104, as before, to observe the amplitude of harmonic response produced thereby. All samples retained in excess of 90% of their original har-monic amplitude after flexing and bendingO
Having thus described the invention in rather full detail, it will be understood that these details need not be strictly adhered to but that further changes and modifications may suggest themselves to one having ordinary skill in the art, all falling within the scope of the invention as defined by the subjoined claims.
Claims (7)
1. For use in a magnetic theft detection system, a marker adapted to generate magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, said marker comprising an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g" ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)] is less than about 0.84.
2. A marker as recited in claim 1, said mar-ker having at least one magnetizable portion integral therewith, the magnetizable portion having coercivity higher than that of said amorphous material.
3. A marker as recited in claim 2, wherein said magnetizable portion is adapted to be magnetized to bias said strip and thereby decreases the amplitude of the magnetic fields generated by said marker.
4. A marker as recited in claim 2, wherein said magnetizable portion comprises a crystalline region of said material.
5. A marker as recited in claim 3, wherein said decrease in amplitude of magnetic fields generated by said marker causes said marker to lose its signal identity.
6. In a magnetic theft detection system mar-ker for generating magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, the improvement wherein:
a. said marker comprising an elongated, duc-tile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g" ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)] is less than about 0.84.
a. said marker comprising an elongated, duc-tile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g" ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)] is less than about 0.84.
7. A magnetic detection system responsive to the presence of an article within an interrogation zone, comprising:
a. means for defining an interrogation zone;
b. means for generating a magnetic field within said interrogation zone;
c. a marker secured to an article appointed for passage through said interrogation zone, said marker comprising an elongated, ductile strip of amorphous ferromagnetic metal having a composition consisting essentially of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g" ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)] is less than about 0.84 said marker being capable of producing magne-tic fields at frequencies which are harmonics of the frequency of an incident field;
d. detecting means for detecting magnetic field variations at selected tones of said harmonics produced in the vicinity of the interrogation zone by the presence of the marker therewithin, said selected tones providing said marker with signal identity and said marker retaining said signal identity after being flexed or bent.
a. means for defining an interrogation zone;
b. means for generating a magnetic field within said interrogation zone;
c. a marker secured to an article appointed for passage through said interrogation zone, said marker comprising an elongated, ductile strip of amorphous ferromagnetic metal having a composition consisting essentially of the formula FeaCrbCcPdMoeCufBgSih where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g" ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)] is less than about 0.84 said marker being capable of producing magne-tic fields at frequencies which are harmonics of the frequency of an incident field;
d. detecting means for detecting magnetic field variations at selected tones of said harmonics produced in the vicinity of the interrogation zone by the presence of the marker therewithin, said selected tones providing said marker with signal identity and said marker retaining said signal identity after being flexed or bent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US31762581A | 1981-11-02 | 1981-11-02 | |
| US317,625 | 1981-11-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1196986A true CA1196986A (en) | 1985-11-19 |
Family
ID=23234528
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000414116A Expired CA1196986A (en) | 1981-11-02 | 1982-10-25 | Amorphous antipilferage marker |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0078401B1 (en) |
| JP (1) | JPS5886694A (en) |
| CA (1) | CA1196986A (en) |
| DE (1) | DE3265257D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4960651A (en) * | 1987-06-08 | 1990-10-02 | Scientific Generics Limited | Magnetic devices |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60204100A (en) * | 1984-03-28 | 1985-10-15 | 日本電気株式会社 | Magnetic maker |
| DE3545647A1 (en) * | 1985-12-21 | 1987-06-25 | Vacuumschmelze Gmbh | DEACTIVATE SECURITY LABEL FOR ANTI-THEFT SECURITY SYSTEMS |
| SE8603415D0 (en) * | 1986-08-14 | 1986-08-14 | Leif Arnold Persson | REMOTE SENSING OF METGLASS IDENTIFIERS |
| DE3717043A1 (en) * | 1987-05-21 | 1988-12-15 | Vacuumschmelze Gmbh | AMORPHOUS ALLOY FOR STRIP-SHAPED SENSOR ELEMENTS |
| US5146204A (en) * | 1990-03-13 | 1992-09-08 | Knogo Corporation | Theft detection apparatus and flattened wire target and method of making same |
| US5029291A (en) * | 1990-04-10 | 1991-07-02 | Knogo Corporation | Electromagnetic sensor element and methods and apparatus for making and using same |
| US5304983A (en) * | 1991-12-04 | 1994-04-19 | Knogo Corporation | Multiple pulse responder and detection system and method of making and using same |
| US5395460A (en) * | 1992-10-16 | 1995-03-07 | Alliedsignal Inc. | Harmonic markers made from Fe-Ni based soft magnetic alloys having nanocrystalline structure |
| US5798693A (en) * | 1995-06-07 | 1998-08-25 | Engellenner; Thomas J. | Electronic locating systems |
| JP5653051B2 (en) | 2010-03-03 | 2015-01-14 | ローランド株式会社 | Electronic keyboard instrument pedal device |
| CN109778082B (en) * | 2019-01-24 | 2020-01-21 | 南京航空航天大学 | High-low temperature annealing toughness iron-based amorphous alloy and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR763681A (en) * | 1933-11-10 | 1934-05-04 | Method of locating objects by modifying a magnetic field | |
| US3665449A (en) * | 1969-07-11 | 1972-05-23 | Minnesota Mining & Mfg | Method and apparatus for detecting at a distance the status and identity of objects |
| US3820104A (en) * | 1972-12-15 | 1974-06-25 | Stop Loss Inc | Method and system for detecting an object within a magnetic field interrogation zone |
| US3856513A (en) * | 1972-12-26 | 1974-12-24 | Allied Chem | Novel amorphous metals and amorphous metal articles |
| US3938125A (en) * | 1974-02-20 | 1976-02-10 | Minnesota Mining And Manufacturing Company | Antipilferage system and marker therefor |
| US4298862A (en) * | 1979-04-23 | 1981-11-03 | Allied Chemical Corporation | Amorphous antipilferage marker |
-
1982
- 1982-10-11 EP EP82108920A patent/EP0078401B1/en not_active Expired
- 1982-10-11 DE DE8282108920T patent/DE3265257D1/en not_active Expired
- 1982-10-25 CA CA000414116A patent/CA1196986A/en not_active Expired
- 1982-11-02 JP JP19327682A patent/JPS5886694A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4960651A (en) * | 1987-06-08 | 1990-10-02 | Scientific Generics Limited | Magnetic devices |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5886694A (en) | 1983-05-24 |
| EP0078401A1 (en) | 1983-05-11 |
| DE3265257D1 (en) | 1985-09-12 |
| EP0078401B1 (en) | 1985-08-07 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |