Thermal Conductivity Gas Sensor Timing for Temperature-Mismatch Correction
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Solution Overview
Problem
Conventional thermal conductivity gas sensors suffer from decreased accuracy and sensitivity due to mismatched temperatures between the environmental temperature sensor and detection sensor, leading to residual errors after temperature correction.
Innovation Solution
A thermal conductivity gas sensor system that includes a measurement unit with a sensor unit and heater unit, a control unit with timing and heater control circuits, and a calculation unit to acquire and correct output signals before and after heating, ensuring accurate temperature correction by stabilizing output signals within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature correction is performed using an environmental temperature sensor, then temperature compensation is achieved, but measurement precision deteriorates due to temperature mismatch between sensors
Solution Approach 1:
The measurement process is segmented into distinct phases: a first measurement phase where the heater is off and temperature matches environmental conditions, and a second measurement phase where the heater is on and temperature differs. By separating these measurements and using the first phase data to correct the second phase data, the patent resolves the temperature mismatch problem while maintaining temperature compensation benefits.
Solution Approach 2:
The patent performs preliminary measurement during the first time period when the heater is not heated and temperature is stable. This preliminary output signal is then used to correct the main measurement taken during the second time period when the heater is active, ensuring accurate compensation without temperature mismatch errors.
2Measurement precision
If the heater is continuously heated to maintain sensor temperature, then detection sensitivity is improved, but temperature stability deteriorates causing measurement drift
Solution Approach 1:
The heater operates periodically rather than continuously - switching between an off state (first time period) and an on state (second time period). This periodic operation allows the sensor temperature to stabilize at environmental temperature during the off phase, eliminating drift, while still achieving the necessary temperature elevation during the on phase for sensitive detection.
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
The system achieves highly accurate gas concentration measurements by stabilizing output signals and correcting for temperature variations, improving sensitivity and reducing residual errors to within ±0.01% in some cases.
Implementation Method 1
a heater unit capable of heating the sensor unit
Implementation Method 2
a thermal conductivity gas sensor that detects a gas concentration by using two sensors including a detection sensor that detects a change in thermal conductivity while being heated by a heater
Data Source
AI summary
A thermal conductivity gas sensor system according to an embodiment includes: a measurement unit that includes a sensor unit capable of measuring a resistance value and a heater unit capable of heating the sensor unit; a control unit that includes a heater control circuit capable of controlling heating and non-heating of the heater unit and a timing control circuit capable of controlling timing of a control signal for heating and non-heating of the heater unit and timing of an output signal from the sensor unit; and a calculation unit that is configured to acquire a first output signal from the sensor unit when the heater unit is not heated and correct a second output signal from the sensor unit when the heater unit is heated using the first output signal.