Thermal and Image Sensor Calibration for Forehead Temperature Accuracy
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Solution Overview
Problem
Existing auto forehead temperature measuring systems suffer from inaccuracies due to variable distances between the subject and the system, environmental temperature fluctuations, and position offsets between thermal and image sensors, leading to false alarms.
Innovation Solution
A temperature measurement system that uses an image sensor and a thermal sensor to capture overlapping images, compensates for position offsets, and calibrates temperatures based on forehead area and environmental conditions using a processor and memory to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a thermal sensor is used to measure temperature at a variable distance, then the measurement range is increased, but the measurement precision deteriorates due to distance variation and environmental interference
Solution Approach 1:
The patent combines a thermal sensor and an image sensor into a unified measurement system. The image sensor captures visual information to determine distance and environmental context, while the thermal sensor measures temperature. By merging these sensors and processing their data together, the system achieves both extended measurement range and improved temperature precision through compensatory algorithms.
Solution Approach 2:
The system dynamically adjusts measurement parameters based on environmental conditions detected by the image sensor. When distance or environmental temperature varies, the system modifies calibration parameters and compensation factors to maintain measurement precision across different operating conditions.
2Ease of operation
If the field of view covers environmental objects to enable auto measurement, then the ease of operation is improved, but the measurement precision deteriorates due to environmental interference
Solution Approach 1:
The system extracts and identifies the target object (e.g., forehead) from the broader environmental field of view using image processing. By separating the target detection function from the temperature measurement function, the system maintains ease of auto-operation while improving precision by focusing thermal measurement only on the identified target region, excluding environmental interference.
Solution Approach 2:
The image sensor acts as an intermediary between the thermal sensor and the environment. It first captures visual information to identify the target and environmental conditions, then guides the thermal sensor's measurement focus. This intermediary process enables automatic operation while filtering out environmental interference before temperature measurement.
3Measurement precision
If a calibration process is implemented to improve temperature accuracy, then the measurement precision is improved, but the loss of time increases due to calibration requirements
Solution Approach 1:
The system performs preliminary calibration by capturing an image frame to identify the target and determine measurement parameters before conducting the actual temperature measurement. This preliminary visual assessment enables the system to pre-adjust calibration factors and measurement settings, achieving high precision without requiring separate, time-consuming calibration steps for each measurement.
Solution Approach 2:
The system performs self-calibration using the image sensor's environmental data. By automatically analyzing the visual scene to determine distance, target position, and environmental conditions, the system generates its own calibration parameters without external intervention, maintaining precision while minimizing time loss.
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
Improves measurement accuracy by aligning and calibrating temperature readings to account for varying distances and environmental factors, reducing false alarms.
Implementation Method 1
a thermal sensor configured to capture a thermal image with a second field of view covering the predetermined heated region having the reference temperature
Data Source
AI summary
There is provided a temperature measurement system including an image sensor, a thermal sensor and a processor. The image sensor captures an image frame. The thermal sensor captures a thermal image. The processor calibrates measured temperatures of the thermal sensor and calibrates offset pixels between the image frame and the thermal image corresponding to different operating distances.