Metal-Oxide Semiconductor Gas Sensor Air Resistance Ratio Correction
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Solution Overview
Problem
Accurate detection of low concentration gases using metal oxide semiconductor gas sensors is challenging due to fluctuating resistance values caused by various factors, making it difficult to convert stationary resistance values into reliable gas detection values.
Innovation Solution
A digital information processing device is used to extract and compare resistance data from a metal oxide semiconductor gas sensor, generating a comparison value based on the ratio of resistance in air to resistance in gas, allowing for accurate detection of gas concentrations by adjusting for changes in air resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If stationary resistance values of the gas sensor are used for gas detection, then the detection process is simple, but the detection accuracy deteriorates due to resistance fluctuations from miscellaneous factors
Solution Approach 1:
The patent applies preliminary action by pre-establishing the relationship between air resistance and gas resistance ratio through prior experiments. The correction values are calculated in advance based on the strong correlation observed between air resistance and the ratio of gas sensor resistance in air versus in gas. This allows the system to compensate for resistance fluctuations without complex real-time calculations, thereby maintaining detection simplicity while improving accuracy.
2Ease of operation
If simple multiplication of stationary resistance values by a constant is used, then the processing is easy, but the conversion to expected gas resistances becomes inadequate
Solution Approach 1:
The patent applies parameter changes by introducing a dynamic correction value that adjusts the conversion process based on the measured air resistance. Instead of using a fixed constant for multiplication, the system calculates a correction value that reflects the current air resistance conditions. This allows the processing to remain relatively simple while significantly improving the accuracy of converting stationary resistance values to expected gas resistance values.
3Device complexity
If the resistance of the gas sensor in air is not considered, then the detection method is straightforward, but the ratio of resistance between air and gas cannot be accurately determined
Solution Approach 1:
The patent applies the taking out principle by separating the measurement of air resistance from the gas detection process. The system first measures the resistance of the gas sensor in air conditions, extracts this information, and uses it as a reference to determine the ratio between air resistance and gas resistance. This extracted air resistance data is then used to correct the gas detection readings, thereby improving accuracy without significantly increasing overall system complexity.
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 method enables precise detection of low concentration gases by correlating air and gas resistance ratios, improving the accuracy of gas concentration measurement and overcoming fluctuations in sensor resistance.
Implementation Method 1
a metal oxide semiconductor gas sensor whose resistance decreases in reducing gases
Data Source
AI summary
A gas detector comprises a metal oxide semiconductor gas sensor whose resistance decreases in reducing gases and a digital information processing device that treats the output of the gas sensor and compares the output with a comparison value for gas detection. The digital information processing device extracts data representing the resistance of the gas sensor in air from the output of the gas sensor and generates the comparison value such that the larger the resistance of the gas sensor in air is, the larger the ratio between the resistance of the gas sensor in air and a resistance value corresponding to the comparison value is.