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Electronic security system

  • US 5,422,632 A
  • Filed: 10/28/1992
  • Issued: 06/06/1995
  • Est. Priority Date: 10/28/1992
  • Status: Expired due to Fees
First Claim
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1. A method for controlling access to an automotive vehicle having an ignition system which controls the operation thereof, a normally open relay interconnected with said ignition system, said ignition system being disabled when said relay is open, and an electronic keypad, comprising the steps of:

  • electrically connecting a computer having processor and memory subsystems electrically connected for bi-directional data transfers therebetween to said electronic keypad such that encoded signals may be propagated from said electronic keypad to said processor subsystem for processing and to said ignition system such that output signals propagated by said processor subsystem may selectively enable or disable said ignition system by selectively closing or opening said relay;

    storing first and second device codes and a first authorization code in said memory subsystem;

    propagating, from storage in a first, touch, memory portion of a first electronic key, an encoded signal having first and second data fields to said processor subsystem by electrically contacting said first electronic key with said electronic keypad;

    comparing said first data field of said propagated encoded signal to said first device code and determining that said propagated encoded signal is an enablement signal if said first data field matches said first device code;

    if said propagated encoded signal is an enablement signal, comparing said second data field of said propagated encoded signal to said first authorization code and determining that said enablement signal is authorized to enable said disabled ignition system if said second data field matches said first authorization code;

    if said propagated encoded signal is not an enablement signal, comparing said first data field of said propagated encoded signal to said second device code and determining that said propagated encoded signal is a reprogramming signal if said first data field matches said second device code;

    if said propagated encoded signal is a reprogramming signal, comparing said second data field of said propagated encoded signal to said first authorization code and determining that said reprogramming signal is authorized to reprogram said computer if said second data field matches said first authorization code;

    if said reprogramming signal is authorized, said processor subsystem requesting reprogramming information from said first electronic key;

    propagating, from storage in a second, non-touch, memory portion of said first electronic key, a second authorization code to said processor subsystem; and

    overwriting said first authorization code with said second authorization code.

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