Infrared Detector Array Drift Correction via Dummy Pixels
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Solution Overview
Problem
Existing non-contact temperature measurement methods, such as infrared thermometers and thermal imaging cameras, face challenges in accurately determining surface temperature distributions, especially in scenarios where temperature drift occurs due to aging effects in infrared detector arrays, requiring complex calibration methods and shutter mechanisms for correction.
Innovation Solution
An infrared measuring system with a detector array comprising reference pixels, measuring pixels, and dummy pixels, where the reference and dummy pixels are insensitive to infrared radiation, allowing for differential signal processing to correct temperature drift without a shutter, using a hand-held thermal imaging camera to provide precise and contact-free temperature measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If infrared detector arrays are used for non-contact temperature measurement, then measurement speed and non-contact capability are improved, but temperature drift due to aging effects occurs reducing measurement accuracy
Solution Approach 1:
The patent introduces dummy pixels as intermediary elements that are not sensitive to infrared radiation but experience the same temperature drift as measuring pixels. These dummy pixels serve as mediators to detect and compensate for temperature drift effects, allowing the system to maintain both fast non-contact measurement capability and accurate temperature readings by subtracting the drift signal from the measurement signal.
Solution Approach 2:
The patent changes the sensitivity parameter of certain pixels (dummy pixels) to be insensitive to infrared radiation while maintaining their temperature response characteristics. This parameter change allows differentiation between infrared signal and temperature drift signal, enabling accurate temperature measurement despite drift occurring in the detector array over time.
2Measurement precision
If shutter mechanisms are added to correct temperature drift, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical shutter system with a purely electronic/digital solution using dummy pixels. Instead of physically blocking infrared radiation to measure drift, the system uses specially designed dummy pixels that electronically simulate the drift condition, eliminating moving parts and mechanical complexity while maintaining drift correction capability.
Solution Approach 2:
The patent creates copies of the measuring pixel structure as dummy pixels that replicate the temperature drift behavior without copying the infrared sensitivity. These dummy pixel copies allow drift measurement through signal processing rather than mechanical intervention, simplifying the overall device structure.
3Measurement precision
If complex calibration methods are used to correct temperature drift, then measurement accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The patent enables the infrared measuring system to automatically correct its own temperature drift using the dummy pixels as built-in reference elements. The system performs self-calibration by comparing measuring pixel signals with dummy pixel signals, eliminating the need for external calibration procedures or specialized operation knowledge, thus maintaining high accuracy while improving ease of operation.
4Measurement precision
If dummy pixels with different thermal conductivity are used, then temperature drift correction is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies different thermal conductivity characteristics locally to specific pixels (dummy pixels versus measuring pixels) within the same detector array. By concentrating the thermal conductivity differentiation only where needed for drift correction rather than requiring uniform precision across all pixels, the system achieves accurate drift correction while reducing overall manufacturing precision requirements.
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
Enables accurate, real-time, and continuous correction of temperature measurements by eliminating temperature drift, improving measurement accuracy and eliminating the need for complex calibration and shutter mechanisms, thus enhancing the reliability of non-contact temperature determination.
Implementation Method 1
The temperature measurement using an infrared-sensitive thermometer is based on the detection of thermal radiation, i.e. infrared radiation in particular in a wavelength range between 3 μm and 50 μm, which is emitted by every object with different intensity depending on its temperature
Implementation Method 2
at least one reference pixel having a first thermal conductivity λRP are connected to the detector array substrate, and which a reference signal URP provide, a plurality of measurement pixels, each with a second thermal conductivity λMP are connected to the detector array substrate, the measurement pixels being sensitive to infrared radiation
Data Source
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AI summary
The invention relates to a method for determining a temperature of a surface (22) without contact, in particular for determining a temperature distribution of a surface (22) without contact, which method proceeds from an infrared measuring system (10, 10a), which at least has an infrared detector array (36) having a detector array substrate (72). According to the invention, at least one reference pixel (65) and blind pixel (64) are provided, which are substantially insensitive to infrared radiation, wherein the first thermal conductivity λ RP (123) of the reference pixel and the third thermal conductivity λ BΡ (122) of the blind pixel are both greater than the second thermal conductivity λ ΜΡ (120) of the measuring pixel, and temperature measurement values T MP (67), which are independent of a reference signal U RP of the at least one reference pixel (65), are determined in that in each case a temperature measurement value T MP,rel 1 (66) of a first measuring pixel (62) and a temperature measurement value Τ ΒΡ,rel 1 (68) of a first blind pixel (64) are subtracted from each other (T MP = T MP-rel 1 - T BP , rel 1), wherein the temperature measurement value T MP-rel 1 (66) and the temperature measurement value Τ ΒΡ,rel 1 (68) are determined by using a reference signal U RP of the same reference pixel (65), temperature measurement values T BP (69), which are independent of the reference signal U RP of the at least one reference pixel (65), are determined in that in each case a temperature measurement value Τ ΒΡ,rel 1 (68) of a first blind pixel (64) and a temperature measurement value Τ ΒΡ,rel 2 (68) of a second blind pixel (64) are subtracted from each other (T BP = T BP,rel 1 - Τ ΒΡ,rel 2), wherein the temperature measurement value T BP,rel 1 (68) and the temperature measurement value Τ ΒΡ,rel 2 (68) are determined by using a reference signal U RP of the same reference pixel (65); temperature measurement values T MP (67) are corrected by pixel-associated temperature drift components T drift (46), wherein the temperature drift components T drift (46) are determined by using temperature measurement values T BP (69) and/or T MP (67). The invention further relates to an infrared measuring system (10, 10a) operated by means of the method.