Changing one of many access codes upon removal of ignition key

• US 5,252,965 A
• Filed: 03/15/1991
• Issued: 10/12/1993
• Est. Priority Date: 03/15/1991
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delco Electronics Corporation (General Motors Company)
• Inventors: Gidwani, Sachal B., Slone, Eric L., Campbell, Kenneth R.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US07/669,708
• Time in Patent Office: 942 Days
• Field of Search: 340/825.56, 340/825.31, 340/825.34, 340/825.54, 307/10.2, 455/343, 540/825.69
• US Class Current: 340/5.23
• CPC Class Codes: G07C 2009/0038 whereby the wake-up circuit is situated in the keyless data carrier
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A system for unlocking any of several vehicles by a passive electronic key coupled to base units in the vehicles by a radio link uses short range LF transmission for signals to the key and VHF transmission for signals to the base units. The key has a ferrite antenna connected to a receiver comprising a comparator. When an operator pulls the door handle, codes stored in the base are transmitted to identify any authorized key within the range. The key has a memory partitioned into separate blocks for different base units and another block for a scratchpad memory. A state machine stores the block addresses and controls access to the blocks according to the transmitted codes. When a block is accessed, a secure ID in the block is sent to the base unit to verify that the key is authorized to unlock the vehicle. The ID can be updated upon command from the base unit using the same codes to assure that an authorized unit is receiving the new ID. The new ID is written to the scratchpad, verified for correctness, and the scratchpad address is exchanged for the address of the block containing the old ID. Auxiliary data specific to the vehicle or to the user of the electronic key may also be stored in the memory blocks and retrieved along with the ID.

Claims

1. A system for secure entry to a plurality of vehicles, each vehicle having an ignition system activated by an ignition key coupled therewith, the system comprising:

a plurality of base units, one for each vehicle, for controlling a vehicle function and at least one remote unit coupled to the base units for communication therewith,

each base unit storing a unique base number and a secure remote ID,

the remote unit having a memory partitioned into assigned memory blocks, one for each base unit, and an additional temporary memory block, each assigned memory block containing a secure ID,

the remote unit further having logic means for selectively assigning a base number to each memory block, for writing an ID to each memory block and for accessing a memory block when a corresponding base number is communicated to the remote unit to read out the secure ID from the memory block for transmission to the base unit,

each base unit having means for automatically initiating an update of an ID, in response to a withdrawal of the ignition key from the ignition system, by transmitting a new ID from the base unit to the remote, and

wherein the logic means is effective, upon receipt of a new ID from a base unit, to write the new ID to the temporary memory block, to reassign the corresponding base number to the temporary memory block, and to reassign the memory block formerly containing the ID for the corresponding base number as a new temporary memory block.

2. The system of claim 1 in which each vehicle has an access door with a lock and an outside access handle and further has power unlocking apparatus for the lock, the base unit is activated by activation of the outside access handle to send its base number to the remote unit and is further effective upon receipt of an ID from the remote which matches its own stored secured remote ID to activate the power unlocking apparatus.