IR Sensor Integration Time Compensation for Thermal Drift

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Solution Overview

Problem

Thermal imaging cameras face significant deviations in measured values due to temperature-induced drift, particularly when transitioning from warm to cold environments, caused by bolometer sensitivity changes and temperature dependencies in control and supply voltages, housing, and lenses, which existing methods struggle to compensate for efficiently without complex electronics or high energy consumption.

Innovation Solution

An IR measuring device with a thermally coupled temperature sensor that adjusts the integration period of the sensor output signal to compensate for temperature-induced drift, allowing for software-controlled optimization of measurement quality without complex electronic circuits, thereby simplifying the structural design and reducing energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If temperature stabilization systems (Peltier elements) are used to maintain constant detector temperature, then measurement precision is improved, but device complexity and energy consumption increase

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidstructural complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameter being controlled from temperature to integration period. Instead of actively stabilizing temperature using complex Peltier elements, the system compensates for temperature-induced drift by dynamically adjusting the integration period based on detected temperature changes, thereby maintaining measurement precision without complex stabilization hardware

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/thermal stabilization system (Peltier elements) with an electronic/software-based compensation method. By using evaluation electronics to detect temperature and adjust integration period parameters, the system substitutes complex thermal management hardware with simpler electronic control

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If Peltier elements are used for active temperature stabilization, then measurement precision is improved, but energy consumption increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system compensates for temperature drift by changing the integration period parameter rather than actively controlling temperature. This passive compensation method consumes minimal energy compared to active Peltier stabilization, while still maintaining measurement accuracy across varying temperatures

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system uses the temperature information already present in the environment to self-compensate for drift. By detecting temperature changes and automatically adjusting integration period, the system serves itself without requiring additional energy-intensive cooling or heating mechanisms

Inventive Principle:
Principle #25Self-service

3Measurement precision

If complex electronic control circuits are used for temperature compensation, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidelectronic circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent simplifies the control approach by adjusting a single parameter (integration period) rather than using complex multi-parameter control circuits. The evaluation electronics detect temperature and directly modify the integration period, eliminating the need for sophisticated electronic temperature stabilization circuits

Inventive Principle:
Principle #35Parameter changes

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 ensures constant sensitivity of the IR radiation detector over a wide ambient temperature range, minimizing environmental influences on measurement accuracy without the need for active temperature stabilization, thus maintaining high dynamic range and reducing operational costs.

Implementation Method 1

the IR radiation detector is thermally coupled to at least one temperature sensor and means for influencing the integration period are formed by an output signal of the at least one temperature sensor

Methodology Applied
Scientific EffectTemperature sensing:

Implementation Method 2

an infrared (IR) measuring device with an IR radiation detector with at least one sensor element which is sensitive to infrared radiation, the at least one sensor element being designed as a bolometer

Methodology Applied
Scientific EffectBolometer effect: Bolometer

Data Source

PatentEP2245849B1Thermographic camera
Publication Date: 2019.03.27 TESTO AG
  • EP2245849B1 patent drawingFigure 1

AI summary

Disclosed is an IR measuring instrument (1) comprising a least one sensor element (29) which is sensitive to infrared radiation and generates an output signal (12) that depends on the radiation incident on the at least one sensor element (29). The output signal (12) for a predefined incident radiation can be varied by means of an integration time. The actual temperature prevailing on the at least one sensor element (29) is detected and is used for varying the integration time in such a way that the integration time compensates the influence of the temperature variations on the output signal (12) of the at least one sensor element (29).