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Gas concentration measuring apparatus compensating for error component of output signal

  • US 6,442,998 B2
  • Filed: 07/09/2001
  • Issued: 09/03/2002
  • Est. Priority Date: 11/02/1998
  • Status: Expired due to Term
First Claim
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1. A gas concentration measuring apparatus comprising:

  • a gas concentration sensor including a diffused resistor into which gasses flow, an oxygen pump cell responsive to application of a voltage to discharge oxygen contained in the gasses and produce a first electric current as a function of concentration of the discharged oxygen, an oxygen detecting cell measuring a concentration of the oxygen discharged by the oxygen pump cell, and a specified gas component measuring cell responsive to application of a voltage to produce a second electric current as a function of concentration of a specified gas component contained in the gasses from which the oxygen is discharged by the first cell;

    a first current measuring circuit measuring the first electric current flowing through said oxygen pump cell of said gas concentration sensor;

    a second current measuring circuit measuring the second electric current flowing through the given gas component measuring cell of said gas concentration sensor; and

    a correcting circuit correcting the second electric current measured by said second current measuring circuit based on the first electric current measured by said first current measuring circuit to compensate for an oxygen-caused error component of the second electric current which depends upon the concentration of oxygen in the gasses and provide an error-corrected second electric current.

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