Passive keyless entry system

• US 5,319,364 A
• Filed: 04/24/1990
• Issued: 06/07/1994
• Est. Priority Date: 05/27/1988
• Status: Expired due to Term

• Current Assignee: Quintras Foundation AG LLC (Intellectual Ventures LLC)
• Original Assignee: Lectron Products Incorporated
• Inventors: Douglas, Daniel G., Waraksa, Thomas J., Gilbert, Lee H., Fraley, Keith D., Kiefer, Richard E.
• Primary Examiner(s): Horabik, Michael
• Application Number:
  US07/513,900
• Time in Patent Office: 1,505 Days
• Field of Search: 340/825.72, 340/825.31, 340/825.69, 340/457, 307/10.1, 307/10.2, 307/10.5, 361/172, 235/382.5, 375/114, 375/116, 370/18, 370/107, 370/118
• US Class Current: 340/5.64
• CPC Class Codes: G07C 2009/0023 with encription of the transmittted data signal
• CPC Class Codes: G07C 2009/00246 periodically, e.g. after a time period
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2009/0096 Electronic keys comprising a non-biometric sensor
• CPC Class Codes: G07C 2209/63 Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: H04L 7/041 using special codes as synchronising signal

Abstract

A passive keyless entry system is disclosed that is specifically adapted for use with automotive vehicles. The system is designed to automatically unlock the vehicle as the operator approaches the vehicle. The system is further designed to automatically lock the vehicle as the operator, carrying the beacon, moves away from the vehicle. The system includes a portable beacon that is carried by the operator, a receiver/controller located in the vehicle, and an antenna connected to the receiver/controller for receiving the encoded transmission from the beacon. The beacon includes a motion sensor to conserve battery life when the beacon is stationary. Transmission between the beacon and the receiver/controller is characterized by a magnetically coupled radio frequency signal embodying differential phase encoded data with error correction coding of the data to enhance noise immunity and signal discrimination.

Claims

1. A keyless entry system for a vehicle comprising:

a portable beacon adapted to be carried by the operator of the vehicle and including transmitter means for transmitting a phase encoded radio frequency beacon signal comprising a plurality of data bits identifying said beacon, said beacon signal being transmitted at a single predetermined carrier frequency with the phase of the beacon signal shifted to distinguish between a logical "1" and a logical "0"; and

receiver means associated with said vehicle and including antenna means for receiving said beacon signal, signal processing means for decoding said beacon signal to recover said plurality of data bits by creating a signal having a frequency related to said carrier frequency and properly phased with respect to said beacon signal, and controller means for determining from said plurality of recovered data bits whether said beacon signal corresponds to a valid beacon and activating a predetermined function associated with said vehicle in response thereto.

2. The keyless entry system of claim 1 wherein said signal processing means includes phase lock loop circuit means for locking onto the frequency and phase of said beacon signal when a beacon is within range of said antenna means and sweep circuit means operatively connected to said phase lock loop circuit means for causing the frequency of said phase lock loop circuit means to gradually sweep up and down around a frequency related to said predetermined carrier frequency when a beacon is not within range of said antenna means.

3. The keyless entry system of claim 2 wherein said signal processing means further includes means for disabling said sweep circuit means when said phase lock loop circuit means has locked onto a beacon signal.

4. The keyless entry system of claim 1 wherein said antenna means is tuned to said predetermined carrier frequency to magnetically couple the energy of said beacon signal into said receiver means.

5. The keyless entry system of claim 2 wherein said controller means has an active state and an inactive state and said controller means is placed in said inactive state whenever a beacon is not within range of said antenna means.

6. The keyless entry system of claim 5 wherein said signal processing means is further adapted to produce a signal that is provided to said controller means and is operative to activate said controller means when a beacon signal has been locked onto.

7. The keyless entry system of claim 1 wherein said beacon further includes a portable power source, motion sensing means for sensing physical motion of said beacon, and circuit means responsive to said motion sensing means for activating said transmitter means to transmit said beacon signal.

8. The keyless entry system of claim 7 wherein the circuitry in said beacon has a current drain on said portable power source in the microamp range when said beacon is stationary.

9. The keyless entry system of claim 1 wherein said beacon signal includes identification information identifying the beacon and function information identifying the predetermined function to be performed by said receiver means.

10. The keyless entry system of claim 9 wherein said beacon signal comprises a digital code having a predetermined number of identification and function bits.

11. The keyless entry system of claim 10 wherein said beacon signal further includes an error correction code comprised of a number of bits equal to said predetermined number of identification and function bits.

12. The keyless entry system of claim 11 wherein said beacon signal is Miller encoded.

13. The keyless entry system of claim 1 further including means for producing an output signal when the ignition key of the vehicle is in the ignition that is provided to said controller means for disabling said controller means.

14. The keyless entry system of claim 13 wherein the vehicle is equipped with an electric door lock mechanism and said controller means is further adapted to automatically activate said electric door lock mechanism to lock the doors of the vehicle after the operator leaves the vehicle and carries said beacon away from the vehicle, provided said output signal is not present.

15. The keyless entry system of claim 14 wherein said controller means is adapted to automatically activate said door lock mechanism to lock the doors of the vehicle a predetermined period of time after said beacon signal is out of range of said antenna means.

16. The keyless entry system of claim 11 wherein the identification, function, and error correction code bits are superimposed with an anti-slip pattern, said anti-slip pattern preventing said signal processing means from decoding the beacon signal at an undesirable location in the bit sequence.

17. A keyless entry system for a vehicle comprising:

a portable beacon adapted to be carried by the operator of the vehicle and including transmitter means for transmitting a phase encoded radio frequency beacon signal comprising a plurality of data bits identifying said beacon, said beacon signal being transmitted at a single predetermined carrier frequency with the phase of the beacon signal shifted to distinguish between a logical "1" and logical "0"; and

receiver means associated with said vehicle, said receiver means including antenna means for receiving said beacon signal, signal processing means for decoding said beacon signal to recover said plurality of data bits by creating a signal having a frequency related to said carrier frequency and properly phased with respect to said beacon signal, said signal processing means including a phase lock loop circuit means for locking onto the carrier frequency and phase of said beacon signal when a beacon is within range of said antenna means and sweep circuit means operatively connected to said phase lock loop circuit means for causing the frequency of said phase lock loop circuit means to gradually sweep up and down around a frequency related to said predetermined carrier frequency when a beacon is not within range of said antenna means, wherein the frequency swept by the sweep circuit means is within the range of the bandwidth of the phase lock loop circuit means, and controller means for determining from said plurality of recovered data bits whether said beacon signal corresponds to a valid beacon and activating a predetermined function associated with said vehicle in response thereto.

18. The keyless entry system of claim 17 wherein said signal processing means further includes means for disabling said sweep circuit means when said phase lock loop circuit means has locked onto a beacon signal.

19. The keyless entry system of claim 17 wherein said antenna means is tuned to said predetermined carrier frequency to magnetically couple the energy of said beacon signal into said receiver means.

20. The keyless entry system of claim 17 wherein said controller means has an active state and an inactive state and said controller means is placed in said inactive state whenever a beacon is not within range of said antenna means.

21. The keyless entry system of claim 20 wherein said signal processing means is further adapted to produce a signal that is provided to said controller means and is operative to activate said controller means when a beacon signal has been locked onto.

22. The keyless entry system of claim 17 further including means for producing an output signal when the ignition key of the vehicle is in the ignition that is provided to such controller means for disabling said controller means.

23. The keyless entry system of claim 22 wherein the vehicle is equipped with an electric door lock mechanism and said controller means is further adapted to automatically activate said electric door lock mechanism to lock the doors of a vehicle after the operator leaves the vehicle and carries said beacon away from the vehicle, provided said output signal is not present.

24. The keyless entry system of claim 23 wherein said controller means is adapted to automatically activate said door lock mechanism to lock the doors of the vehicle a predetermined period of time after said beacon signal is out of range of said antenna means.

25. A keyless entry system for a vehicle comprising:

a portable beacon adapted to be carried by the operator of the vehicle and including transmitter means for transmitting a phase encoded radio frequency beacon signal comprising a plurality of data bits for identifying the beacon signal including an identification code and an error correction code, said beacon signal being transmitted at a single predetermined carrier frequency with the phase of the beacon signal shifted to distinguish between a logical "1" and a logical "0"; and

receiver means associated with said vehicle, said receiver means including antenna means for receiving said beacon signal, signal processing means for decoding said beacon signal to recover said plurality of data bits by creating a signal having a frequency related to said carrier frequency and being properly phased with respect to said beacon signal, and controller means for determining from said plurality of recovered data bits the content of said identification code and accordingly whether said beacon signal corresponds to a valid beacon and activating a predetermined function associated with said vehicle in response thereto.

26. The keyless entry system of claim 25 wherein said signal processing means includes means for creating a signal having a frequency related to said carrier frequency and properly phased with respect to said beacon signal comprising a phase lock loop circuit means for locking onto the frequency and phase of said beacon signal when a beacon is within range of said antenna means and sweep circuit means operatively connected to said phase lock loop circuit means for causing the frequency of said phase lock loop circuit means to gradually sweep up and down around a frequency related to said predetermined carrier frequency when a beacon is not within range of said antenna means.

27. The keyless entry system of claim 26 wherein said signal processing means further includes means for disabling said sweep circuit means when said phase lock loop circuit means has locked onto a beacon signal.

28. The keyless entry system of claim 25 wherein said antenna means is tuned to said predetermined carrier frequency to magnetically couple the energy of said beacon signal into said receiver means.

29. The keyless entry system of claim 25 wherein said controller means has an active state and an inactive state and said controller means is placed in said inactive state whenever a beacon is not within range of said antenna means.

30. The keyless entry system of claim 28 wherein said signal processing means is further adapted to produce a signal that is provided to said controller means and is operative to activate said controller means when a beacon signal has been locked onto.

31. The keyless entry system of claim 25 wherein said beacon further includes a portable power source, motion sensing means for sensing physical motion of said beacon, and circuit means responsive to said motion sensing means for activating said transmitter means to transmit said beacon signal.

32. The keyless entry system of claim 31 wherein the circuitry in said beacon has a current drain on said portable power source in the microamp range when said beacon is stationary.

33. The keyless entry system of claim 25 wherein said beacon signal includes function information identifying the predetermined function to be performed by said receiver means.

34. The keyless entry system of claim 32 wherein said beacon signal comprises a digital code having a predetermined number of identification and function bits.

35. The keyless entry system of claim 33 wherein said error correction code is comprised of a number of bits equal to said predetermined number of identification and function bits.

36. The keyless entry system of claim 34 wherein said beacon signal is Miller encoded.

37. The keyless entry system of claim 25 further including means for producing an output signal when the ignition key of the vehicle is in the ignition that is provided to said controller means for disabling said controller means.

38. The keyless entry system of claim 35 wherein the vehicle is equipped with an electric door lock mechanism and said controller means is further adapted to automatically activate said electric door lock mechanism to lock the doors of the vehicle after the operator leaves the vehicle and carries said beacon away from the vehicle, provided said output signal is not present.

39. The keyless entry system of claim 37 wherein said controller means is adapted to automatically activate said door lock mechanism to lock the doors of the vehicle a predetermined period of time after said beacon signal is out of range of said antenna means.

40. A keyless entry system for a vehicle comprising:

a portable beacon adapted to be carried by the operator of the vehicle and including transmitter means for transmitting at a predetermined frequency an encoded sinusoidal beacon signal comprising a plurality of data bits identifying said beacon, said beacon further including an antenna drive circuit and a tuned antenna circuit adapted to resonate at said predetermined frequency, said antenna drive circuit providing a pulsed signal to said tuned antenna circuit at a predetermined periodic rate related to said predetermined frequency such that the pulses in said pulsed signal substantially coincide with the peaks in said beacon signal, wherein the beacon signal is a phase encoded radio frequency signal being transmitted at a single predetermined carrier frequency with the phase of the beacon signal shifted to distinguish between a logical "one" and a logical "zero"; and

receiver means associated with said vehicle and including antenna means for receiving said beacon signal, signal processing means for decoding said beacon signal to recover said plurality of data bits, and controller means for determining from said plurality of recover data bits whether said beacon signal corresponds to a valid beacon in activating a predetermined function associated with said vehicle in response thereto.

41. The keyless entry system of claim 40 wherein said signal processing means includes means for creating a signal having a frequency related to said carrier frequency and properly phased with respect to said beacon signal comprising phase lock loop circuit means for locking onto the frequency and phase of said beacon signal when a beacon is within range of said antenna means and sweep circuit means operatively connected to said phase lock loop circuit means for causing the frequency of said phase lock loop circuit means to gradually sweep up and down around a frequency related to said predetermined carrier frequency when a beacon is not within range of said antenna means.

42. The keyless entry system of claim 40 wherein said antenna means is tuned to said predetermined carrier frequency to magnetically couple the energy of said beacon signal into said receiver means.

43. The keyless entry system of claim 40 wherein said beacon further includes a portable power source, motion sensing means for sensing physical motion of said beacon, and circuit means responsive to said motion sensing means for activating said transmitter means to transmit said beacon signal.

44. The keyless entry system of claim 40 wherein said predetermined rate is approximately every 1.5 cycles of the frequency beacon signal.

45. The keyless entry system of claim 43 wherein the circuitry in said beacon has a current drain on said portable power source in the microamp range when said beacon is stationary.

46. The keyless entry system of claim 40 wherein said beacon signal includes function information identifying the predetermined function to be performed by said receiver means.

47. The keyless entry system of claim 46 wherein said beacon signal comprises a digital code having a predetermined number of identification and function bits.

48. The keyless entry system of claim 47 wherein said beacon signal further includes an error correction code comprised of a number of bits equal to said predetermined number of identification and function bits.

49. The keyless entry system of claim 48 wherein said beacon signal is Miller encoded.