Passive keyless entry system

Claim 2

A keyless entry system, comprising: (a) a means for defining an interrogation zones; (b) generating means for generating a magnetic field having a frequency band within said interrogating zone said generating means including a interrogating coil; (c) a marker responsive within at least one of said interrogation zones to undergo a substantial change in its effective magnetic permeability at a preselected frequency within said frequency band that provides the marker with signal identity, said marker comprising at least one strip of magnetostrictive, ferromagnetic , material, said strip being adapted to be magnetically biased and thereby armed to resonate mechanically at said preselected frequency within the frequency band of said magnetic field; (d) detecting means for detecting resonance of said marker within said interrogation zones; (e) decoding means for comparing said detected marker resonance against a predefined code to verify parity therebetween; and (f) actuating means for enabling said entry system in response to an indication of parity from said decoding means.

Claim 3

2, A keyless entry system as recited in claim 1, further comprising an activating means for detecting the presence of an object within said interrogation zones and activating said generating means in response to the presence of said object.

Claim 4

A keyless entry system as recited in claim 2, wherein said activating means comprises a proximity sensor disposed in the vicinity of said interrogation zone and adapted to undergo a change in electronic status in response to the presence of an object proximate thereto, and switching means for energizing said generating means in response to said change in electronic status.

Claim 5

A keyless entry system as recited in claim 1, wherein each of said generating and said detecting means comprises at least one antenna coil.

Claim 6

A keyless entry system as recited in claim 4, wherein said antenna coils of said generating and said detecting means are coplanar.

Claim 7

A keyless entry system as recited in claim 5, wherein said generating means comprises a pair of antenna coils disposed adjacent to each other and driven by said generating means alternately at phase angles of 0° and 180° with respect to each other.

Claim 8

A keyless entry system as recited in claim 4, wherein said system is disposed in a motor vehicle and said antenna coils of said generating and detecting means are disposed in a side rear view mirror of said vehicle.

Claim 9

A keyless entry system, comprising: (a) a means for defining a plurality of interrogation zones; (b) generating means associated with each of said interrogation zones for generating therein a magetic field having a frequency band, said generating means including a plurality of interrogating coils, at least one of said interrogating coils being disposed within each of said interrogation zones; (c) a marker responsive within at least one of said interrogation zones to undergo a substantial change in its effective magnetic permeability at a preselected frequency within said frequency band that provides the marker with signal identity, said marker comprising at least one strip of magnetostrictive, ferromagnetic meterial, said strip being adapted to be magnetically biased and thereby armed to resonate mechanically at said preselected frequency within the frequency band of said magnetic field; (d) a plurality of detecting means for detecting resonance of said marker within said interrogation zones; (e) decoding means for comparing said detected marker resonance against a predefined code to verify parity therebetween; and (f) a plurality of actuating means for enabling a plurality of electronic devices associated with said entry system in response to an indication of parity from said decoding means.

Claim 10

A keyless entry system, comprising: (a) a means for defining a plurality of interrogation zones; (b) generating means associated with each of said interrogation zones for generating therein a magetic field having a frequency band, said generating means including a plurality of interrogating coils, at least one of said interrogating coils being disposed within each of said interrogation zones; (c) a marker responsive within at least one of said interrogation zones to undergo a substantial change in its effective magnetic permeability at a preselected frequency within said frequency band that provides the marker with signal identity, said marker comprising at least one strip of magnetostrictive, ferromagnetic meterial, said strip being adapted to be magnetically biased and thereby armed to resonate mechanically at said preselected frequency within the frequency band of said magnetic field; (d) a plurality of detecting means for detecting resonance of said marker within said interrogation zones; (e) decoding means for comparing said detected marker resonance against a predefined code to verify parity therebetween; and (f) a plurality of actuating means for enabling a plurality of electronic devices associated with said entry system in response to an indication of parity from said decoding means.

Claim 11

A keyless entry system as recited in claim 8, further comprising a plurality of activating means for detecting the presence of an object withing each of said interrogation zones and activating said generating means in response to the presence of said object.

Claim 12

A keyless entry system as recited in claim 9, t wherein each of said activating means comprises a proximity sensor disposed in the vicinity of a different one of said interrogation zones and adapted to undergo a change in electronic status in response to the presence of an object proximate thereto, and switching means for energizing said generating means in response to said change in electronic status.