Thermal Imaging Temperature Calibration for High-Temperature Accuracy

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Solution Overview

Problem

Existing thermal imaging cameras suffer from temperature measurement errors due to the approximation of temperature difference versus output code difference curves using polynomial fitting functions, which increase in high-temperature regions and widen temperature measurement regions.

Innovation Solution

A temperature measuring device and method that utilizes an inverse function to obtain a curve-fitted function of temperature difference versus output code difference, reducing errors by fitting a quadratic curve to match the actual temperature of an object.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If contactless temperature measurement is performed using a thermal imaging camera, then convenience and hygiene are improved, but measurement precision deteriorates due to influence from surrounding temperature and reflected infrared rays

Engineering Contradiction:
Improvecontactless measurement convenienceVSAvoidtemperature measurement precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

A reference object with known temperature is introduced as an intermediary to calibrate the thermal imaging camera. The camera measures the infrared radiation from this reference object to establish a reference value, which then serves as a basis for correcting subsequent measurements of the target object, thereby compensating for environmental influences and improving precision

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the temperature parameter of the reference object to multiple different temperatures, and the camera measures infrared radiation at each temperature level. By establishing a relationship between the reference object's temperature and the camera's measured values across different parameters, the system creates a calibration curve that enables accurate correction of target object measurements

Inventive Principle:
Principle #35Parameter changes

2Loss of time

If temperature measurement is performed using a contactless thermal imaging camera, then time consumption is reduced, but measurement precision deteriorates due to lack of direct contact

Engineering Contradiction:
Improvemeasurement timeVSAvoidtemperature measurement precision
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The reference object is prepared in advance with known temperature characteristics before the actual measurement of the target object. The thermal imaging camera performs preliminary calibration measurements on the reference object to establish accurate reference values, which are then used to correct the subsequent target object measurement, ensuring precision without contact

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If thermal imaging camera measures infrared radiation to determine temperature, then non-contact measurement is achieved, but measurement accuracy deteriorates due to reflected infrared rays from surrounding objects

Engineering Contradiction:
Improvenon-contact measurement capabilityVSAvoidtemperature measurement accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The reference object acts as a mediator that provides known temperature information. By measuring the infrared radiation from the reference object with known temperature, the system can identify and compensate for the effects of reflected infrared rays from surrounding objects, thereby improving the accuracy of target object temperature measurements

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Significantly reduces temperature measurement errors between the actual object temperature and the measured temperature using thermal imaging cameras, especially in high-temperature regions and wide measurement ranges.

Implementation Method 1

a thermal imaging camera to measure a reference object at a plurality of different temperatures and to measure a target object

Methodology Applied
Scientific EffectInfrared radiation detection: Infrared Radiation

Implementation Method 2

a thermal imaging camera to measure a reference object at a plurality of different temperatures and to measure a target object

Methodology Applied
Scientific EffectThermal imaging: Thermography

Data Source

PatentEP3926311B1Temperature measuring device and method using thermal imaging camera, and computer-readable recording medium
Publication Date: 2026.05.20 U ELECTRONICS
  • EP3926311B1 patent drawingFigure 1
  • EP3926311B1 patent drawingFigure 2
  • EP3926311B1 patent drawingFigure 3

AI summary

A temperature measuring device using a thermal imaging camera according to an embodiment of the present invention may comprise: a first operation module for obtaining, for the thermal imaging camera, a curve of temperature difference versus output code difference where the X axis represents the output code difference and the Y axis represents the temperature difference indicated by a plurality of measured values; a second operation module for obtaining a function of temperature difference versus output code difference, the function curve-fitted by using the curve of temperature difference versus output code difference; and a third operation module for measuring the temperature of an object by applying the curve-fitted function of temperature difference versus output code difference.