Dual Humidity Sensor Dew Point Measurement Without Sawtooth Error
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Solution Overview
Problem
Existing dew point measurement technologies experience inaccuracies and time windows of unavailable data due to cyclic heating of humidity sensors, particularly at low dew point temperatures, leading to a 'sawtooth effect' and delayed accurate readings.
Innovation Solution
A measuring device with two humidity sensor units, one for dew point correction and one for continuous measurement, thermally decoupled and using a control unit to cyclically determine a dew point correction parameter, correcting the continuous dew point measurement of the second unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a humidity sensor is heated cyclically to maintain calibration, then measurement reliability is improved, but measurement continuity deteriorates due to time windows where accurate dew point determination is unavailable
Solution Approach 1:
The measuring device is divided into two functionally independent humidity sensor units: a first sensor unit dedicated to cyclic heating and calibration maintenance, and a second sensor unit dedicated to continuous dew point measurement. This segmentation allows each sensor to perform its specialized function without interfering with the other, eliminating the measurement gaps that occur when a single sensor must both measure continuously and be heated for calibration.
Solution Approach 2:
A control unit acts as an intermediary that coordinates the operation of both sensor units. It manages the cyclic heating of the first sensor unit while simultaneously processing data from the second sensor unit to provide continuous corrected dew point measurements. The control unit mediates between the conflicting requirements of calibration maintenance and continuous measurement.
2Measurement precision
If a humidity sensor is heated cyclically to correct drift, then measurement accuracy is improved, but response speed deteriorates due to delayed accurate readings after cooling
Solution Approach 1:
By separating the calibration function (first sensor unit with heating element) from the measurement function (second sensor unit), the system eliminates the response delay that occurs when a single sensor must cool down after heating. The second sensor unit remains at stable temperature and can provide immediate accurate readings without waiting for thermal equilibration.
Solution Approach 2:
The first sensor unit performs preliminary calibration actions through cyclic heating, establishing correction parameters in advance. These pre-determined correction parameters are then applied to the continuous measurements from the second sensor unit, eliminating the need for the measurement sensor itself to undergo heating cycles that would delay its response.
3Device complexity
If a single humidity sensor is used for both continuous measurement and cyclic heating, then device complexity is reduced, but measurement precision deteriorates due to the sawtooth effect
Solution Approach 1:
The device is segmented into two specialized sensor units with distinct functions: the first sensor unit handles cyclic heating for calibration, while the second sensor unit handles continuous measurement. This segmentation, while increasing component count, eliminates the sawtooth effect and significantly improves measurement precision by preventing the thermal interference that occurs when a single sensor must serve both purposes.
Solution Approach 2:
Each sensor unit is optimized for its specific function: the first sensor unit is designed with heating capability for calibration maintenance, while the second sensor unit is optimized for stable, continuous measurement. This local optimization of quality ensures that each component performs its designated function with maximum effectiveness, with the measurement sensor remaining thermally stable for accurate readings.
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
Ensures continuous and accurate dew point temperature determination without time windows of inaccuracy, eliminating the 'sawtooth effect' and enabling rapid response to dew point changes.
Implementation Method 1
the temperature of the first humidity sensor unit is changed cyclically and thereby a dew point correction parameter is determined
Implementation Method 2
the change in capacitance of a suitable polymer is typically used as the measure of relative humidity
Implementation Method 3
The dew point temperature is not usually measured directly, but rather by measuring temperature and relative humidity and appropriately calculating these values
Data Source
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Figure 3a
AI summary
The present invention relates to a measuring device and a method for determining and outputting the dew point temperature. A first humidity sensor unit (10; 110; 210) is configured for determining at least one dew point correction parameter and comprises a first humidity sensor (11), a first temperature sensor (12), and a temperature change element (13). A second humidity sensor unit (20; 120; 220) is configured for continuously determining the dew point temperature and comprises a second humidity sensor (21) and a second temperature sensor (22).By means of a control unit (30) the temperature of the first humidity sensor unit (10; 110; 210) is changed via the temperature change element (13) and a dew point correction parameter is determined; furthermore, the dew point correction parameter from the first humidity sensor unit (10; 110; 210) is used to correct measured values of the second humidity sensor unit (20; 120; 220) and to continuously output corrected dew point temperatures based on the corrected measured values.