Humidity Sensor Auto-Calibration via Self-Heating
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Solution Overview
Problem
Conventional humidity sensor devices require labor-intensive and time-consuming calibration processes, especially when calibrating integrated circuit chips, which can be costly and inefficient, particularly due to long stabilization times and the need for precise climatic chambers.
Innovation Solution
A method involving self-heating of the humidity sensor device, where the device adjusts its calibration offset based on temperature changes, allowing for auto-calibration by determining differences in dew points at varying temperatures, thereby maintaining accurate relative humidity measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods using climatic chambers are employed, then measurement precision is improved, but time consumption and device complexity increase significantly
Solution Approach 1:
The humidity sensor device performs self-calibration by utilizing its own operational characteristics. The device determines dew point at different temperatures and adjusts its calibration offset automatically without requiring external climatic chambers or manual intervention, thereby eliminating the time-consuming conventional calibration process while maintaining precision.
Solution Approach 2:
The calibration method changes the temperature parameter of the sensor device to different values (first temperature and second temperature) and determines dew point at each temperature. By observing how the dew point determination varies with temperature, the system calculates and adjusts the calibration offset, achieving accurate calibration through parameter variation rather than requiring complex external equipment.
2Measurement precision
If conventional calibration methods using climatic chambers are employed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The sensor device calibrates itself using only its own components and operational characteristics. The processing means within the device determines dew point, controls temperature variation, and adjusts calibration offset automatically. This self-service approach eliminates the need for complex external climatic chambers, test benches, and manual calibration procedures, significantly reducing device complexity and cost while maintaining calibration accuracy.
Solution Approach 2:
The invention extracts the essential calibration function from the complex external climatic chamber system and implements it within the sensor device itself. By taking out only the necessary temperature variation and dew point determination capabilities and integrating them into the sensor, the system achieves calibration without requiring the full complexity of traditional calibration equipment.
3Productivity
If integrated circuit chips are calibrated at manufacture time, then productivity is improved, but manufacturing precision may be compromised due to lack of individual calibration
Solution Approach 1:
Each humidity sensor device performs individual self-calibration automatically during its operation. This eliminates the need for time-consuming individual calibration of each device at assembly time, as the device can self-correct its calibration offset. Consequently, high productivity is maintained through batch manufacturing while individual calibration accuracy is achieved through automatic self-calibration of each device.
Solution Approach 2:
The system performs preliminary rough calibration at manufacture time for all chips in batch, then enables individual precise calibration through automatic self-calibration during operation. This preliminary action at manufacture allows high-volume production while the subsequent self-calibration ensures individual precision without requiring manual intervention at assembly time.
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 enables efficient and reliable auto-calibration of humidity sensors, reducing calibration time and costs while ensuring accurate translation of measured voltage to real environmental humidity levels, allowing for continuous correct operation during service time.
Implementation Method 1
The capacitance of the film changes in response to humidity. The sensor detects humidity by detecting changes in capacitance between the pair of electrodes
Implementation Method 2
a layer or coating of a dielectric, highly moisture-sensitive material overlaying the electrodes and positioned so as to be capable of absorbing water from the surrounding atmosphere
Implementation Method 3
heating the humidity sensor device, in particular, by self-heating, thereby heating the environment (locally) to a second temperature higher than the first temperature
Data Source
AI summary
The present invention relates to a method of calibrating a humidity sensor device, comprising the steps determining a first dew point and a first relative humidity at a first temperature in an environment by the humidity sensor device using a first calibration offset; subsequently heating the humidity sensor device, in particular, by self-heating, thereby heating the environment to a second temperature higher than the first temperature; subsequently determining a second dew point at the second temperature by the humidity sensor device; subsequently determining whether the determined second dew point differs from the determined first dew point by more than a predetermined difference; and subsequently changing the first calibration offset of the humidity sensor device by a predetermined value to obtain a second calibration offset, if it is determined that the determined second dew point differs from the determined first dew point by more than the predetermined difference.