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

• US 20050007235A1
• Filed: 11/08/2001
• Published: 01/13/2005
• Est. Priority Date: 11/08/2001
• Status: Active Grant

• Current Assignee: VEGA Elettronica SRL
• Original Assignee: VEGA Elettronica SRL
• Inventors: Stasi, Paolo
• Granted Patent: US 7,301,438 B2
• Time in Patent Office: Days
• US Class Current: 340/5.720
• 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 an unauthorized use of a coded access and/or ignition key (4) with electronic identification to be inserted in a receptacle or lock (5), comprising the steps of:

procuring and installing a device of directional emission of electromagnetic energy (VSI, 6), positioning the antenna or directional emitter (6) of the device at a certain distance from the position of said receptacle or lock (5) hiding or disguising its presence;

irradiating toward means functioning at a certain frequency (2) present in said receptacle or lock (5) for sensing a signal containing information of said recognition code of the key, an amplitude modulated electromagnetic signal of the same working frequency of said means (2) to corrupt the information content of said sensed signal.

2. The method of claim 1, wherein said means (2) comprise a primary winding through which a sinusoidal signal at said frequency is forced to contactlessly powering circuits contained in said access key (4) and the frequency of said modulated electromagnetic signal is equal to the frequency of said sinusoidal signal forced in said primary winding.

3. The method of claim 1, wherein said electromagnetic signals is modulated at a frequency equal to or multiple of the bit rate at which the information contained in said sensed signal is read.

4. An ancillary protection system against an unauthorized use of a coded access and/or ignition key (4) with electronic identification to be inserted in a receptacle or lock (5), comprising a recognition device (PR) of the code of said key (4) in the form of a sequence of bits having a winding (2) with function of primary winding of an air-core transformer functioning at a certain frequency and for contactlessly powering a circuit contained in the key (4) comprising a winding (3) acting as secondary winding of said air-core transformer and an integrated circuit supplied from the voltage produced by magnetic induction in said secondary winding (3) and adapted to alternate phases of current absorption to phases of substantially null current absorption on a time base corresponding to said bit sequence of the key code and inducing on said primary winding (2) a corresponding back electromotive force, a comparator of the voltage present on said primary winding (2) 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 identification code of said key (4),

characterized in that it comprises

a device of directional emission of electromagnetic energy (VSI, 6) installable in a remote position from the lock (5), irradiating toward said primary winding (2) a modulated electromagnetic signal of the same frequency of the frequency of functioning of said air core transformer, automatically activated when the system is active by command (ENABLE) of the authorized user of the key, upon inserting the key (4) in said receptacle or lock (5), such to induce on said primary winding (2) a disturbing voltage.

5. The ancillary protection system of claim 4, wherein said electromagnetic signal is modulated using a modulating signal of a second frequency equal to or a multiple of the rate at which the coding bits of said sensed signal are read by said recognition device (PR).

6. The ancillary protection system according to claim 4, wherein said device of directional emission of electromagnetic energy (VSI, 6) comprises a directional antenna or emitter (6) composed of a LC resonant circuit. (7, 8, 9) tuned on said frequency of the emitted signal, constituted by a capacitor (9) and by a coil (8) wound on a ferromagnetic core (7) functioning as directional emitter (6) driven by a circuit (VSI) generating said modulated signal.

7. The ancillary protection system of claim 6, characterized in that said generating circuit (VSI) comprises:

a second microprocessor unit (CPU) turned on by a command (ENABLE) and receiving a synchronization signal (SYNC) when the key (4) is inserted in said receptacle or lock (5);

a generator (OSC) of a signal whose frequency is equal to the working frequency of the primary winding (2);

a generator of a modulation frequency (FREQ);

an amplitude modulator (MOD) of said signal at said working frequency with said modulation frequency;

an amplifier (AMP) coupled to the output of said modulator (MOD) and a tuned stage (TUNE) coupling the modulated and amplified signal to said directional emitter (6), means (ENABLE, DECODER) for activating the system by command (ENABLE) of the user.

8. The ancillary protection system according to claim 6, wherein said coil (8) is constituted by a double winding of Linz wire on a core of ferrite (7).

9. The ancillary protection system according to claim 7, wherein said command (ENABLE) is issued by the user via radio or by a remote control or by typing a code on a keyboard.

10. A car anti-theft device comprising an ancillary protection system according to claim 7, wherein said first microprocessor unit enables the ignition of the engine if the read bit sequence corresponds to the identification code of said key (4).