Resonant tag circuits having one or more fusible links

• US 4,021,705 A
• Filed: 03/24/1975
• Issued: 05/03/1977
• Est. Priority Date: 03/24/1975
• Status: Expired due to Term

• Current Assignee: George Jay Lichtblau
• Original Assignee: George Jay Lichtblau
• Inventors: Lichtblau, George Jay
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US05/561,085
• Time in Patent Office: 771 Days
• Field of Search: 317/101 A, 340/280, 340/258 R, 340/152 T, 343/6.5 SS, 336/200
• US Class Current: 361/765
• CPC Class Codes: G08B 13/242 Tag deactivation
• CPC Class Codes: G08B 13/2431 Tag circuit details
• CPC Class Codes: H01L 27/01 comprising only passive thin-film or thick-film elements formed on a common insulating substrate passive two-terminal components without a potential-jump or surface barrier for integrated circuits, details thereof and multistep manufacturing processes therefor H01L28/00
• CPC Class Codes: H03H 5/02 without voltage- or current-dependent elements
• CPC Class Codes: H05K 1/0293 Individual printed conductors which are adapted for modification, e.g. fusable or breakable conductors, printed switches
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/09727 Varying width along a single conductor; Conductors or pads having different widths
• CPC Class Codes: H05K 2201/10181 Fuse
• CPC Class Codes: H05K 2203/171 Tuning, e.g. by trimming of printed components or high frequency circuits
• CPC Class Codes: H05K 2203/175 Configurations of connections suitable for easy deletion, e.g. modifiable circuits or temporary conductors for electroplating; Processes for deleting connections

Abstract

A planar resonant tag circuit especially useful in electronic security systems wherein the value of a circuit component can be electrically and selectively altered by one or more fusible links integrally formed with the planar circuit. At least one fusible link is formed in bridging relationship with one or more turns of a planar inductor and which can be selectively fused by application of an energizing field to activate the resonant circuit or to alter the resonant characteristics of the circuit.

Claims

1. A multifrequency resonant tag circuit comprising:

a planar substrate of electrically insulative material;

a first conductive path formed on a surface of said substrate in a configuration to define a first inductor;

a second conductive path formed on said substrate in a configuration to define a second inductor;

first and second pairs of conductive areas formed on said substrate, each pair having conductive areas in alignment on respective opposite surfaces of said substrate to define a capacitor, the conductive areas on each substrate surface being electrically connected to said paths on the common substrate surface at selected points to define first and second tuned circuits; and

a conductive link having at least a portion of predetermined size, said link provided on a surface of said substrate in short circuit with at least a portion of one of said conductive paths and operative to fuse upon application of an energizing field to thereby alter the inductance of the associated conductive path and correspondingly alter the resonant properties of said tag circuit.

2. A resonant tag circuit according to claim 1 further including:

a conductive path provided through said substrate and completing at least one of said tuned circuits by interconnection of said first or second conductive path and one of said conductive areas.

3. A resonant tag circuit according to claim 1 wherein said conductive link is provided as a planar path on the same surface of said substrate as said first and second conductive paths.

4. A resonant tag circuit according to claim 1 wherein said conductive link is formed as a planar conductive path on the surface of said substrate opposite to that containing said first and second conductive paths and in alignment with one of said first and second conductive paths to be in mutual coupling relationship therewith.

5. A resonant tag circuit according to claim 1 further including:

a conductive path of predetermined size provided in circuit with said tag circuit on a surface of said substrate and operative to fuse upon application of an energizing field at a second resonant frequency.

6. A resonant tag circuit comprising:

a planar substrate of electrically insulative material;

a first conductive path formed on a surface of said substrate in a configuration to define an inductor;

at least one pair of conductive areas formed on said substrate in alignment on respective opposite surfaces of said substrate to define at least one capacitor, the conductive areas on the substrate surface containing said conductive path being electrically connected to said path at selected points to define a tuned circuit having a predetermined resonant frequency;

a conductive link of predetermined size provided on a surface of said substrate in short circuit with at least a portion of said conductive path and operative to fuse upon application of an energizing field to thereby alter the inductance of the associated conductive path and correspondingly alter the resonant properties of said tag circuit.

7. A resonant tag circuit according to claim 6 wherein said conductive link of predetermined size is provided on the surface of said substrate containing said conductive path.

8. A resonant tag circuit according to claim 6 wherein said conductive link of predetermined size is provided on a surface of said substrate opposite to the surface containing said conductive path and in alignment therewith to provide mutual coupling therebetween.

9. A multifrequency resonant tag circuit containing at least first and second tuned circuits respectively resonant at first and second frequencies comprising:

a planar substrate of electrically insulative material;

a first conductive path formed on a surface of said substrate in a configuration to define a first inductor;

a second conductive path formed on said substrate in a configuration to define a second inductor;

first and second pairs of conductive areas formed on said substrate each pair having conductive areas in alignment on respective opposite surfaces of said substrate to define a capacitor, the conductive areas on the substrate surface containing said first and second conductive paths being electrically connected to said paths at selected points to define said first and second tuned circuits;

a conductive path of predetermined size provided in circuit with said tag circuit on a surface of said substrate and operative to fuse upon application of electromagnetic energy at said second resonant frequency to thereby destroy the resonant properties of said tag circuit at said first frequency;

a conductive path of predetermined size provided in short circuit with at least a portion of one of said first and second conductive paths and operative to fuse upon application of electromagnetic energy at a third frequency to thereby render the tag circuit resonantly operative at said first and second frequencies; and

a conductive path provided through said substrate and completing at least one of said tuned circuits by interconnection of said first or second conductive path and one of conductive areas.

10. A multifrequency resonant tag circuit containing at least first and second tuned circuits respectively resonant at said first and second frequencies comprising:

a planar insulative substrate having formed on one surface thereof

a first conductive area centrally formed on said substrate surface;

a second conductive area formed along one side of said substrate surface;

a first conductive path arranged on said substrate surface between and in electrical connection with said first and second conductive areas;

a second conductive path formed on said substrate surface between and in electrical connection with said second conductive area and a third conductive area formed on said substrate surface near a corner thereof;

and wherein the opposite surface of said substrate includes;

fourth, fifth and sixth conductive areas each in alignment and substantially coextensive with said respective first, second and third conductive areas formed on said one substrate surface;

a conductive path connecting said fourth and fifth conductive areas;

a conductive path through said substrate connecting said third and sixth conductive areas;

a conductive path interconnecting said second and third conductive areas and dimensioned to fuse upon application of an electromagnetic field of predetermined power at a third frequency to thereby render said tag circuit operative at said first and second frequencies; and

a conductive path interconnecting said fifth and sixth conductive areas and dimensioned to fuse upon application of an electromagnetic field of predetermined power at said second frequency to thereby destroy the resonant properties of said tag circuit at said first frequency.

11. A multifrequency resonant tag circuit containing at least first, second and third tuned circuits respectively resonant at first, second and third frequencies comprising:

a planar insulative substrate having formed on one surface thereof;

a first conductive area;

a second conductive area;

a first conductive path in electrical connection with said first and second conductive areas arranged in a configuration to define a first inductor;

a third conductive area;

a second conductive path in electrical connection with said second conductive area and said third conductive area and formed in a configuration to define a second inductor;

said planar insulative substrate having formed on a second surface thereof;

fourth, fifth and sixth conductive areas each in alignment and substantially coextensive with said respective first, second and third conductive areas formed on said one substrate surface, said first and fourth conductive areas and said second and fifth conductive areas comprising respective first and second capacitors;

a conductive path connecting said fourth and fifth conductive areas;

a conductive path through said substrate connecting said third and sixth conductive areas;

a conductive path interconnecting said second and third conductive areas to short circuit said first inductor and dimensioned to fuse upon application of an electromagnetic field of predetermined power at a third frequency to thereby render said tag circuit operative at said first and second frequencies; and

a conductive path interconnecting said fifth and sixth conductive areas and dimensioned to fuse upon application of an electromagnetic field of predetermined power at said second frequency to thereby destroy the resonant properties of said tag circuit at said first frequency;

said first inductor, second inductor and second capacitor being electrically connected to form said first tuned circuit; and

said first capacitor, second inductor and second capacitor being electrically connected to form said second tuned circuit;

said second inductor and second capacitor being electrically connected to form said third tuned circuit.

12. A multifrequency resonant tag circuit containing at least first, second and third tuned circuits respectively resonant at first, second and third frequencies comprising:

a planar insulative substrate having formed on one surface thereof;

a first conductive area;

a second conductive area;

a first conductive path in electrical connection with said first and second conductive areas arranged in a configuration to define a first inductor;

a third conductive area;

a second conductive path in electrical connection with said second conductive area and said third conductive area and formed in a configuration to define a second inductor;

said planar insulative substrate having formed on a second surface thereof;

fourth, fifth and sixth conductive areas each in alignment and substantially coextensive with said respective first, second and third conductive areas formed on said one substrate surface, said first and fourth conductive areas and said second and fifth conductive areas comprising respective first and second capacitors;

a conductive path connecting said fourth and fifth conductive areas;

a conductive path through said substrate connecting said third and sixth conductive areas;

a conductive path in closed circuit with said fifth area and in alignment with at least one of said first and second conductive paths and defining a third inductor mutually coupled to at least one of said first and second inductors and dimensioned to fuse upon application of an electromagnetic field of predetermined power at a third frequency to thereby render said tag circuit operative at said first and second frequencies; and

a conductive path interconnecting said fifth and sixth conductive areas and dimensioned to fuse upon application of an electromagnetic field of predetermined power at said second frequency to thereby destroy the resonant properties of said tag circuit at said first frequency;

said first inductor, second inductor and second capacitor being electrically connected to form said first tuned circuit; and

said first capacitor, second inductor and second capacitor being electrically connected to form said second tuned circuit;

said second inductor and second capacitor being electrically connected to form said third tuned circuit.