Sensor Circuit Leakage Suppression via Periodic Heating
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Solution Overview
Problem
Solid state sensors used for detecting environmental hazards like hydrogen sulfide face accuracy issues due to undesired electrical current leakage between the sensor and heating elements, leading to erroneous readings, especially in varying environmental conditions.
Innovation Solution
A suppression circuit is introduced to mitigate current leakage by alternately providing operating current to the heating element and equalizing the voltage across the sensor and heating elements, allowing accurate resistance measurement only when the heating element is disconnected from the higher voltage source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a heating element is used to maintain the sensor at a desired operating temperature, then the sensor accuracy is improved, but current leakage between the heating element and sensor circuit causes measurement errors
Solution Approach 1:
The patent applies periodic action by alternating between two circuit configurations: a first configuration where the heating element is connected to a first voltage source for temperature maintenance, and a second configuration where the heating element is disconnected and the sensor is connected to a second voltage source for accurate measurement. This periodic switching eliminates current leakage during measurement while maintaining temperature during heating operations.
Solution Approach 2:
The patent segments the operational cycle into distinct phases: a heating phase where the heating element is active and connected to the first voltage source, and a measurement phase where the sensor is isolated from the heating circuit and connected to the second voltage source. This segmentation allows the system to separate the conflicting functions of heating and measuring, eliminating interference between them.
2Temperature
If the heating element is continuously connected to power, then the sensor maintains optimal temperature, but energy is wasted and current leakage increases
Solution Approach 1:
The system uses periodic action to switch between heating and measurement modes. The heating element is only connected to power during the heating phase when temperature maintenance is needed, and is disconnected during the measurement phase. This periodic operation maintains sensor temperature when required while eliminating continuous energy waste and reducing current leakage during measurement operations.
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 approach significantly reduces errors in hydrogen sulfide concentration readings by minimizing current leakage, maintaining sensor accuracy across different environmental conditions and extending sensor lifespan.
Implementation Method 1
The sensor element senses the environmental constituent by presenting an electrical parameter which varies with the constituent... the sensor's resistance can vary in response to the concentration of hydrogen sulfide in ambient air
Implementation Method 2
solid state sensors may be provided with an electrical resistance heating element to maintain the sensor at a desired operating temperature... the resistive heating element is in direct contact with the solid state sensor for rapid conductive heating of the sensor
Data Source
AI summary
An apparatus for sensing a constituent in an environment including a sensor circuit and a suppression circuit. The sensor circuit has a sensor element and an operating state control element. The sensor element senses the constituent by presenting an electrical parameter which varies as a function of a degree of the constituent. The control element maintains the sensor at a preferred operating state. A detected electrical parameter of said sensor element is subject to error resulting from a leakage of electrical current between the control element and the sensor element. The suppression circuit reduces or stops the leakage to reduce the error.