Communications: electrical – Continuously variable indicating – With meter reading
Reexamination Certificate
1998-06-17
2001-05-22
Horabik, Michael (Department: 2735)
Communications: electrical
Continuously variable indicating
With meter reading
C340S010100, C340S010300, C340S010400, C340S010330, C340S010340
Reexamination Certificate
active
06236333
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to passive security systems, and more particularly to a passive remote keyless entry system for a vehicle.
Remote Keyless Entry (RKE) is being installed at an ever increasing rate in automobiles. The dramatic rate of installation is being fueled by consumer acceptance and subsequent demand of RKE systems. Additional improvements in RKE system technology are possible and are even being requested by the consumer. The problem of fumbling for the existing active RKE FOB while standing in the rain or when in an emergency situation has provided the motivation to design and implement a passive RKE system.
Existing passive RKE systems cause unintentional lock actuations when the consumer is in the near vicinity of the vehicle whose desires do not include unlocking the vehicle (“false alarms”). False alarms present an additional drain on the vehicle and FOB batteries, prematurely reducting the operating life of the locking system. They can also present a security issue if the false alarm leaves the doors unlocked.
Many RKE schemes have been investigated incorporating capacitive/inductive proximity sensors and optical sensors. Many problems are associated with such sensors in addition to the prohibitive cost. For example, optic sensors suffer from contaminants (i.e. dirt, grease, salt, etc.) causing the lenses (apertures) to become opaque to the optic energy. Thermal sensors suffer in that they are unsuitable for detecting gloved hands (if under the door handle) or wearing winter clothes.
The task is further complicated by the relatively long actuation time required for the lock motors/solenoids and mechanical linkage to change the state of the lock(s). This means the passive RKE system must “read the consumer's mind”, at a distance far enough away from the lock (door) to allow sufficient time for the locks to unlock the door, without compelling the consumer to manipulate the door handle more than once.
SUMMARY OF THE INVENTION
The present invention provides a passive remote keyless entry system which includes a plurality of sensors each associated with a door of the vehicle (including the trunk). The sensors detect the presence and distance of a key fob from the sensor. By monitoring the distance of the key fob from the sensor, the sensor can determine if the key fob (and the driver) is approaching the associated door, moving away from the associated door, or simply passing by. If a sensor determines that the key fob is approaching it, an interrogation signal is sent from the security system to the key fob, in response to which the key fob sends a code. If the proper code is transmitted by the key fob, the door associated with the sensor is unlocked. Similarly, if the sensor determines that the key fob is moving away from the associated door, the associated door is locked or all of the doors are locked.
Preferably, the security system includes a sleep mode in which power is conserved. When one of the sensors determines that the key fob is within a second predetermined threshold distance greater than the first predetermined threshold distance from the sensor the security system wakes up and enters full power mode. Then, when the key fob is detected to be within the first predetermined threshold distance, the security system is ready to transmit the interrogation signal.
REFERENCES:
patent: 3725939 (1973-04-01), Saltzstein
patent: 5826450 (1998-10-01), Lerchner et al.
patent: 5973611 (1999-10-01), Kulha et al.
patent: 0 735 219 A2 (1996-02-01), None
patent: 2 732 798 (1996-11-01), None
patent: 2 749 607 (1997-12-01), None
International Search Report, Oct. 27, 1999.
Bangachon William
Brooks & Kushman P.C.
Horabik Michael
Lear Automotive Dearborn Inc.
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