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Sobriety interlock

  • US 4,592,443 A
  • Filed: 01/16/1984
  • Issued: 06/03/1986
  • Est. Priority Date: 02/01/1983
  • Status: Expired due to Fees
First Claim
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1. A sobriety interlock comprising:

  • a power supply;

    a ground terminal;

    an "ignition on" input terminal;

    an "OK to drive" output terminal;

    means defining a breath receiving port;

    a thermocouple adjacent to and aligned with said port, said thermocouple being connected to said power supply and said ground terminal and having a junction and a temperature output line for electrical signals generated in response to the temperature of a breath sample flowing through said port, said thermocouple having means for heating the junction thereof to a temperature different from that of a breath sample received in said port;

    a gas sensor adjacent to and aligned with said port, said gas sensor being connected to said power supply and said ground terminal and having an alcohol level output line for electrical signals generated in response to the alcohol level of a breath sample flowing through said port;

    an analog-to-digital converter having a first input connected to the thermocouple output line, a second input connected to the gas sensor output line, and a plurality of output lines for digital signals indicating the temperature and alcohol level of a breath sample flowing through the port;

    a microcomputer responsive to a signal at the "ignition on" terminal to read the digital signals on the converter output lines and to provide a signal at said "OK to Drive" terminal as a function of whether the alcohol level in a breath sample is different from a predetermined level.

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