Ancillary protection system against the unauthorized use of an access and/or ignition key

• US 7,301,438 B2
• Filed: 11/08/2001
• Issued: 11/27/2007
• Est. Priority Date: 11/08/2001
• Status: Expired due to Fees

• Current Assignee: VEGA Elettronica SRL
• Original Assignee: VEGA Elettronica SRL
• Inventors: Stasi, Paolo
• Primary Examiner(s): Holloway, III; Edwin C.
• Application Number:
  US10/490,420
• Publication Number:
  US 20050007235A1
• Time in Patent Office: 2,210 Days
• Field of Search: 340/825.72, 340/825.69, 340/10.1, 340 561- 564, 340/5.72, 340/5.31, 340/426.11, 340/426.36, 340/426.13, 340/426.16, 307/10.5
• US Class Current: 340/5.72
• CPC Class Codes: B60R 25/21 using hidden switches
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user
• CPC Class Codes: G07C 2009/00777 by induction
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

A protection system against the unauthorized use of an access key with electronic identification that, when is active, prevents the recognition of the original access key. This is done by disturbing the transfer of the code by magnetic induction from the circuit incorporated in the key to the device of contactless powering and recognition of the identification code installed in the lock. A code information corrupting disturbance in produced by a device of directionally emitting electromagnetic energy toward the point of space of magnetic coupling between a primary winding of an air transformer of the recognition device of the lock and the secondary winding of the air transformer coupled to an integrated circuit contained in the key. The emitting device acts from a distance that may be even larger than one meter from the so equipped lock.

Claims

1. A method of ancillary protection against unauthorized use of an unpowered uniquely coded access and/or ignition key embedding an electronic identification periodic bit coding means connected to a secondary coil to be inserted in a receptacle or lock having electrically powered bit code sensing electronic means connected to a primary coil driven at a certain frequency, for transferring electric power to the said secondary coil in the access and/or ignition key, the method comprising the steps of:

procuring and installing a device of directional emission of electromagnetic energy, positioning the antenna or directional emitter of the device at a certain distance from the position of said receptacle or lock, hiding or disguising its presence;

irradiating toward said primary and secondary coils, respectively associated to said receptacle and to the key inserted therein an electromagnetic signal of the same working frequency of said coupled primary and secondary coils, amplitude modulated at a frequency randomly varying between a lower bound equal to the bit rate of the periodic bit coding and an upper bound equal to a multiple of the bit rate, equal or greater than the rate of said periodic bit coding and detectable by said sensing electronic means to corrupt the information content of said sensed code.

2. The method of claim 1, wherein irradiation toward said primary and secondary coils staffs upon inserting said injection key into said receptacle or lock.

3. An ancillary protection system against unauthorized use of an unpowered uniquely coded access and/or ignition key embedding an electronic identification periodic bit coding means connected to a secondary coil, to be inserted in a receptacle or lock having electrically powered bit code sensing electronic means connected to a primary coil constituting an ak-core transformer with said secondary coil, driven at a certain frequency for contactlessly transferring electric power to the said secondary coil in the access and/or ignition key and comprising a recognition device of the code of said key in the form of a sequence of bits, said periodic bit coding means in said key being an integrated circuit supplied at a rectified and regulated voltage produced by magnetic induction in said secondary coil and adapted to alternate phases of current absorption to phases of substantially null current absorption on a time base corresponding to said periodic bit sequence of code identification and inducing on said primary coil a corresponding back electromotive force, a comparator in said code recognition device of the voltage amplitude present on said primary winding generating a signal representing said bit sequence, and at least a microprocessor unit receiving as input said signal and validating the key if the detected bit sequence corresponds to the unique identification code of said key,

the ancillary protection system comprising:

a device of directional emission of electromagnetic energy disguisingly installed in a remote position from the lock, irradiating toward said air transformer an electromagnetic signal of the same frequency of the frequency of functioning of said air core transformer and amplitude modulated at a frequency randomly varying between a lower bound equal to the bit rate of the periodic bit coding and an upper bound equal to a multiple of the bit rate;

means for determining an automatic activation of said disguisingly and remotely installed device when enabled by a user'"'"'s command upon insertion of the key in said receptacle or lock, such to induce on said primary winding a code recognition preventing disturbance voltage.

4. The ancillary protection system according to claim 3, wherein said device of directional emission of electromagnetic energy comprises a directional antenna or emitter composed of a LC resonant circuit tuned on said working frequency of the air transformer, constituted by a capacitor and by a coil wound on a ferromagnetic core functioning as directional emitter driven by a generating circuit for said modulated signal.

5. The ancillary protection system of claim 4, characterized in that said generating circuit comprises:

a second microprocessor unit enabled by a user'"'"'s command for receiving a synchronization signal when the key is inserted in said receptacle or lock;

a generator of a signal of frequency equal to the working frequency of the primary winding;

a generator of a modulation frequency;

an amplitude modulator of said signal at said working frequency with said modulation frequency; and

an amplifier coupled to the output of said modulator and a tuned stage coupling the modulated and amplified signal to said directional emitter, means for activating the system by command of the user.

6. The ancillary protection system according to claim 5 wherein said command is issued by the user via radio by a remote control or by typing a code on a keyboard.

7. A car anti-theft device comprising an ancillary protection system according to claim 5, wherein said first microprocessor unit enables the ignition of the engine if the read bit sequence corresponds to the identification code of said key.

8. The ancillary protection system according to claim 3 wherein said coil comprises a double winding of Litz wire on a core of ferrite.

9. A method of protecting against an unauthorized use of a passively powered and uniquely coded key having a periodic bit coding and a secondary coil associated therewith for use in conjunction with a receptacle or lock having a primary coil driven at a certain frequency, the method comprising:

providing an emission of electromagnetic energy at the certain frequency; and

directing the emission of electromagnetic energy to the secondary coil and the primary coil so as to interfere with sensing of an electrically powered bit code by the receptacle or lock,

where said step of providing an emission comprises amplitude modulating the electromagnetic energy at a frequency randomly varying between a lower bound equal to the bit rate of the periodic bit coding and an upper bound equal to a multiple of the bit rate and equal to or greater than a bit rate of said periodic bit coding, and

wherein said amplitude modulating corrupts an information content of said sensed electrically powered bit code.

10. The method of claim 9, wherein said step of directing the emission of electromagnetic energy comprises positioning an antenna or directional emitter at a certain distance from a position of said receptacle or lock, the method further comprising hiding or disguising the antenna or directional emitter.

11. An ancillary protection system, the system comprising:

a receptacle or lock comprising an electrically powered code recognition device configured to sense a bit code;

a primary coil operatively connected to the code recognition device;

a passively powered and uniquely coded key, said key comprising means for embedding an electronic identification periodic bit coding in the key;

a secondary coil arranged in the key and operatively coupled to the means for embedding, wherein the primary coil and the secondary coil form a transformer operating at a working frequency, and wherein the means for embedding receives electrical power from the primary coil through the secondary coil,

wherein the code recognition device senses the embedded electronic identification periodic bit coding in the key in the form of a sequence of bits of a certain bit rate; and

a directional electromagnetic energy emitting device hiddenly remotized from the receptacle or lock,

a circuit generating and feeding a signal to said directional electromagnetic energy emitting device of the same working frequency of the transformer and amplitude modulated at a frequency randomly varying between a lower bound equal to the bit rate of the periodic bit coding and an upper bound equal to a multiple of the bit rate, and

wherein said emitting device selectively emits an electromagnetic signal onto the receptacle or lock of the same working frequency so as to induce a code recognition disturbance voltage on said primary winding that prevents the code recognition device from correctly sensing the sequence of bits.

12. The system of claim 11, wherein said means for embedding in said key comprises an integrated circuit supplied by a voltage produced by magnetic induction in said secondary coil.

13. The system of claim 12, wherein said voltage produced by magnetic induction comprises a voltage produced by alternating phases of current absorption and phases of substantially null current absorption on a time base corresponding to said periodic bit sequence, whereby said voltage produced by magnetic induction is induced on said primary coil as a corresponding back electromotive force.

14. The system of claim 11, wherein the directional electromagnetic energy emitting device is disguised in a remote position from the lock so as to not be readily identified as a part of the system.

15. The system of claim 11, wherein said directional electromagnetic energy emitting device comprises a directional emitter comprising an LC resonant circuit tuned to said working frequency of the transformer, said LC resonant circuit comprising a capacitor and a coil wound on a ferromagnetic core.

16. The system of claim 15, wherein the coil comprises a double winding of Litz wire on the ferromagnetic core.

17. The system of claim 16, wherein said generating circuit comprises:

a microprocessor configured to receive a synchronization signal when the key is inserted in said receptacle or lock;

a signal generator producing a signal having a frequency equal to the working frequency of the primary winding;

a generator of a modulation frequency; and

an amplitude modulator;

said modulator amplitude modulating said signal at said working frequency of the transformer at said modulation frequency.

18. The system of claim 17, further comprising an amplifier coupled to the output of said modulator and a tuned stage arranged to couple the modulated and amplified signal to said directional emitter.

19. The system of claim 17, further comprising means for enabling the system by a user'"'"'s command.