Gas Sensor Thermistor Circuit for Humidity Interference Cancellation
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Solution Overview
Problem
Existing gas sensors face measurement errors due to the influence of gases different from the detection target, requiring computation processing and increasing sensor size with separate measurement parts for oxygen and humidity.
Innovation Solution
A gas sensor design featuring thermistors with different operating temperatures and a correction resistor to cancel humidity influence directly through hardware, eliminating the need for computation processing by connecting thermistors in series and a correction resistor in parallel to accurately measure target gas concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate measurement parts for oxygen concentration and humidity are provided outside the hydrogen sensor unit, then the influence of different gases can be corrected, but the size of the entire sensor increases and computation processing is required
Solution Approach 1:
The patent combines multiple measurement functions (hydrogen detection, oxygen concentration measurement, and humidity measurement) into a single integrated sensor unit. The sensor unit includes a hydrogen sensor element, an oxygen concentration sensor element, and a humidity sensor element all housed together, eliminating the need for separate external measurement parts and reducing overall sensor size while maintaining measurement accuracy.
Solution Approach 2:
The sensor unit is designed as a multi-functional device that simultaneously performs hydrogen gas detection, oxygen concentration measurement, and humidity measurement. This universal design allows one compact unit to replace multiple separate sensors, reducing device complexity while providing comprehensive gas analysis capabilities.
2Measurement precision
If separate measurement parts for oxygen concentration and humidity are provided outside the hydrogen sensor unit, then the influence of different gases can be corrected, but computation processing is required
Solution Approach 1:
The patent replaces the computational correction method with a hardware-based electrical circuit solution. The sensor unit includes a signal processing circuit that uses electrical connections (series and parallel configurations of resistors and sensor elements) to automatically compensate for humidity and oxygen interference, eliminating the need for complex computation processing while maintaining high measurement accuracy.
3Measurement precision
If computation processing is performed for calculation of gas concentration, then measurement accuracy can be improved, but the device complexity increases
Solution Approach 1:
The patent substitutes computational algorithms with an electrical circuit-based signal processing system. The measurement circuit uses predetermined resistor connections and electrical signal combinations to automatically calculate and compensate for interference gases, providing accurate gas concentration measurements without requiring complex computation processing or additional software algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for highly accurate elimination of interference from non-target gases without computation processing, ensuring precise measurement of target gas concentrations.
Implementation Method 1
a first sensor part S1 including a first thermistor Rd1 and a first heater resistor MH1 that heats the first thermistor Rd1
Implementation Method 2
a first sensor part S1 including a first thermistor Rd1 and a first heater resistor MH1 that heats the first thermistor Rd1
Data Source
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AI summary
An object of the present invention is to measure a concentration of a detection target gas with eliminating the influence of a gas different from a detection target gas. A gas sensor includes: a first thermistor Rd1 having a resistance value that changes according to a concentration of a first gas with a first sensitivity and changes according to a concentration of a second gas with a second sensitivity; a second thermistor Rd2 connected in series to the first thermistor, the second thermistor having a resistance value that changes according to a concentration of the first gas with a third sensitivity that is lower than the first sensitivity and changes according to a concentration of the second gas with a fourth sensitivity that is different from the second sensitivity; and a correction resistor R1 connected in parallel with the first or second thermistor. According to the present invention, the first and second thermistors are connected in series to each other, and a change in potential at the connection point between the first and second thermistors according to the concentration of the second gas is canceled by the correction resistor, so that it is possible to easily and highly accurately eliminate the influence of the second gas without requiring computation processing, allowing accurate computation of the concentration of the first gas.