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US 4,896,143 AGranted
Gas concentration sensor with dose monitoring
AssigneeThe Quantum Group, Inc.
InventorsEarl M. Dolnick, Terry G. Anderson
Life of this patent
Estimating the term…
Abstract
A tin oxide carbon monoxide sensor is operated in a manner to exclude effects of ambient temperature and humidity. Resistance of the sensor is measured at a lower temperature and again at a higher temperature. The target gas concentration is determined as a function of the first and second resistances, thereby cancelling the effects of humidity and ambient temperature.
Claims10
A method for measuring a target gas concentration comprising:
- measuring the resistance of a conductive metal oxide gas sensor exposed to a target gas at a first, relatively lower equilibrium temperature;
- measuring the resistance of the conductive metal oxide gas sensor exposed to the target gas at a second, relatively higher equilibrium temperature;
- and
- solving an equation for determining a plurality of values of target gas concentration as a function of resistance values, storing in a memory a plurality of such target gas concentration values as a function of resistance values, and using both of the measured resistance values to look up in the memory a value of target gas concentration.
1 more element
A method for measuring a target gas concentration comprising:
- measuring the resistance of a conductive metal oxide gas sensor exposed to a target gas at a first, relatively lower equilibrium temperature;
- measuring the resistance of the conductive metal oxide gas sensor exposed to the target gas at a second, relatively higher equilibrium temperature;
- and
- solving an equation for target gas concentration as a function of both measured resistances for determining target gas concentration as a function of at least the first and second resistances.
1 more element
A gas concentration sensor system comprising:
- a conductive metal oxide gas sensor having resistance which is variable in response to gas concentration, including concentration of a target gas;
- means connected to the gas sensor for measuring a first resistance of the gas sensor at a lower temperature;
- means connected to the gas sensor for intermittently heating the gas sensor from the lower temperature to a higher temperature;
- means connected to the gas sensor for measuring a second resistance of the gas sensor at the higher temperature;
- means connected to the measuring means for determining target gas concentration as a function of both the first and second resistances;
- register means for accumulating values of target gas concentration from the determining means;
- means for adding values to the register means when target gas concentration exceeds a selected value;
- and
- means for subtracting values from the register means when target gas concentration is less than the selected value.
6 more elements
A method for monitoring carbon monoxide concentration comprising:
- periodically measuring concentration of carbon monoxide;
- adding to a digital register when the concentration exceeds a selected value;
- and
- subtracting from the digital register when the concentration is less than the selected value.
1 more element
Dependencies are inferred from the claim text.