Bolometric Detector Prediction Unit for Thermal Inertia Compensation

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Solution Overview

Problem

Thermal imaging cameras face challenges in rapidly generating measurement signals that accurately represent detectable infrared radiation due to the time delay caused by bolometric measuring cells, which are designed as delay elements with thermal resistance and capacity, leading to measurement inertia and delayed response to changes in infrared radiation intensity and wavelength.

Innovation Solution

A system comprising a bolometric detector array with a prediction unit that determines a prediction signal by calculating difference data sets between successive measurement data sets and using a parameter representing the measuring cells' time constant to compensate for the time delay, allowing for quick and quantitative representation of infrared radiation intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If bolometric measuring cells are used to detect infrared radiation, then infrared radiation detection is achieved, but measurement signal generation is delayed due to thermal resistance and capacitance

Engineering Contradiction:
Improveinfrared radiation detection accuracyVSAvoidmeasurement signal delay
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The prediction unit performs preliminary calculations using previously received measurement data sets to predict future measurement values before they are actually measured. By computing prediction values based on historical data and the known time constant behavior, the system anticipates the delayed measurement signals, effectively compensating for the thermal inertia of the bolometric cells without waiting for the actual delayed measurements to occur.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If bolometric measuring cells with thermal capacitance are used, then infrared radiation absorption is achieved, but measurement response time is slowed

Engineering Contradiction:
Improveinfrared radiation detection reliabilityVSAvoidmeasurement response speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The prediction unit uses feedback from previously received measurement data sets to continuously refine and update prediction values. By analyzing the pattern of past measurements and the known time constant characteristics of the bolometric cells, the system generates corrected prediction values that compensate for the inherent thermal delay, maintaining reliable detection while improving response speed.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If thermal capacitance is increased in measuring cells, then infrared radiation energy storage is improved, but time delay of measurement signal increases

Engineering Contradiction:
Improvethermal energy storage capacityVSAvoidmeasurement signal time delay
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The system changes the parameter of time constant from a fixed physical property of the bolometric cells to a variable that can be compensated for through computational methods. By using the known time constant value in prediction calculations and adjusting prediction values based on the relationship between previous measurements and the time constant, the system effectively counteracts the delay caused by thermal capacitance while maintaining the energy storage benefits.

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

The system enables the rapid generation of prediction signals that accurately represent the detected infrared radiation, overcoming the measurement inertia of bolometric measuring cells and providing timely and quantitative data, enabling faster detection of infrared radiation changes.

Implementation Method 1

The measuring principle can relate to the absorption of infrared radiation and the heating of the bolometric measuring cell

Methodology Applied
Scientific EffectAbsorption of infrared radiation: Absorption (EM radiation)

Implementation Method 2

the absorption of infrared radiation and the heating of the bolometric measuring cell

Methodology Applied
Scientific EffectHeating of bolometric measuring cell: Heating

Implementation Method 3

Each bolometric measuring cell therefore has a thermal capacitance. The thermal capacitance represents a value for the amount of thermal energy that can be stored by the respective bolometric measuring cell

Methodology Applied
Scientific EffectThermal capacitance: Capacitance

Implementation Method 4

Each bolometric measuring cell is also characterized by a thermal resistance. The thermal resistance of the respective measuring cell is a thermal parameter and/or a measure of the temperature difference that occurs in the respective measuring cell when a heat flow passes through it

Methodology Applied
Scientific EffectThermal resistance: Conduction (thermal)

Data Source

PatentEP3789743B1System and method for generating a prediction signal and a thermal imaging camera
Publication Date: 2024.07.17 BASLER AG
  • EP3789743B1 patent drawingFigure 1~3
  • EP3789743B1 patent drawingFigure 4~7
  • EP3789743B1 patent drawingFigure 6

AI summary

The invention relates to a system (2) for generating a prediction signal u, comprising: a bolometric detector array (4) with a plurality of bolometric measuring cells (6), and a prediction unit (8). Each bolometric measuring cell (6) is configured as a delay element with a time constant Tau. The detector array (4) is configured to generate a measurement data set Mtj at successive measurement times tj, each data set representing the measured values ​​mi,tj of the measuring cells (6) at the respective measurement time tj. The prediction unit (8) is configured to determine a difference data set Dtj for each received measurement data set Mtj compared to the previous measurement data set Mtj-1.Furthermore, the prediction unit (8) is configured to determine, for each received measurement data set Mtj, a prediction data set Ptj based on the difference data set Dtj thereby determined and a characteristic value representing the measuring cells (6), and to generate a prediction signal u that represents the prediction data sets Ptj. The invention also relates to a corresponding method and a thermal imaging camera (10) with such a system (2).