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Theft warning system

  • US 4,574,268 A
  • Filed: 02/22/1985
  • Issued: 03/04/1986
  • Est. Priority Date: 05/22/1984
  • Status: Expired due to Term
First Claim
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1. A theft warning system for use in a vehicle having a plurality of doors with door lock devices, comprising:

  • first means for detecting whether an ignition switch of the vehicle is open or closed and generating a signal according to the condition of the ignition switch;

    second means for detecting whether each of said vehicle doors is open or closed and generating a signal according to the condition of each said door;

    third means for detecting whether said door lock device of at least one of said doors is locked or unlocked, and generating a signal according to the condition of said door lock device;

    fourth means for detecting whenever one of said door lock device is unlocked by actuation of a door key, and generating a signal indicating that one of said door lock devices has been so unlocked;

    control means for receiving the signals generated by the first, second, third and fourth means, said control means setting a theft detecting condition when a last of said doors is closed by an operator outside of the vehicle while the ignition switch is open and all of said door lock devices are locked, and for generating a theft warning signal when, after setting of said theft detecting condition, one of said vehicle doors is opened or unlocked without use of a door key; and

    alarm means responsive to said theft warning signal for generating an alarm signal.

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