Thermal Imaging Cavity Emissivity Tracking
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Solution Overview
Problem
Infrared temperature measurements on targets with low or variable emissivity often result in substantial errors, and existing methods like single-spot thermometers and thermal imagers face challenges in accurately aligning with moving cavities, leading to inaccuracies in temperature profiling.
Innovation Solution
A method that determines the line of optimal emissivity enhancement in a cavity formed by a sheet material and a roller, using thermal imaging to identify and track this line, thereby generating an accurate temperature profile, even when the cavity is not fixed or aligned perfectly with the imager.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single-spot infrared thermometer is used to measure temperature, then the device is simple to operate, but only a single track on the strip can be monitored and precise alignment is difficult to maintain
Solution Approach 1:
The patent transitions from single-spot (0D/1D) temperature measurement to two-dimensional thermal imaging, allowing the entire cavity region to be monitored simultaneously. This dimensional expansion enables both ease of operation and high measurement precision by capturing temperature data across the whole cavity without requiring precise alignment of a single measurement point.
Solution Approach 2:
The thermal imager serves multiple functions: it monitors the entire cavity region, identifies the optimal emissivity enhancement line, and provides comprehensive temperature profiling. This multi-functionality resolves the contradiction by enabling both simple operation (single device does everything) and precise measurement (multiple measurement points simultaneously).
2Measurement precision
If an infra-red linescanner is used to monitor temperature profile across the strip, then a temperature profile can be obtained, but alignment is even more difficult than for a single-spot thermometer
Solution Approach 1:
The system automatically identifies the optimal emissivity enhancement line within the cavity region without requiring manual alignment. The thermal imager captures the entire cavity, and the system self-adjusts to find and track the line of maximum emissivity enhancement, eliminating the alignment difficulty while maintaining precise temperature profiling capability.
Solution Approach 2:
The system dynamically adapts to cavity position changes by continuously identifying and tracking the optimal emissivity enhancement line. This dynamic adjustment capability allows the system to maintain measurement precision even when the cavity moves or changes position, without requiring manual realignment.
3Ease of operation
If a thermal imager is aimed at the wedge cavity, then a two dimensional temperature image can be displayed without precise alignment, but extracting temperatures from the cavity region in real time is difficult due to cavity movement and misalignment
Solution Approach 1:
The system uses feedback from the thermal image data to automatically identify and track the optimal emissivity enhancement line. By analyzing the thermal image to locate the cavity region and extract temperature data from the optimal line, the system maintains measurement precision despite cavity movement, while keeping the operation simple (no manual alignment needed).
Solution Approach 2:
The system performs preliminary identification of the cavity region and optimal emissivity enhancement line from the thermal image before extracting temperature data. This preliminary action ensures that even if the cavity moves or misaligns, the correct region is identified and temperature extraction is performed accurately from the appropriate location.
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 significantly increases the accuracy of temperature monitoring by consistently enhancing emissivity and tracking the optimal emissivity line, reducing errors caused by misalignment and movement of the cavity within the image.
Implementation Method 1
Infrared energy is emitted by all materials at temperatures above absolute zero. This energy travels in the form of electromagnetic waves with wavelengths typically in the range 0.7 microns to 20 microns.
Implementation Method 2
Infrared imaging systems convert the energy transmitted in the infrared spectrum into a visible light image.
Implementation Method 3
One way to alleviate such errors is to aim the infra-red thermometer into a 'cavity' in the target. This cavity acts to a greater or lesser degree as a 'black-body' cavity. The effective value of the emissivity is raised and stabilised by reflections within the cavity.
Implementation Method 4
A 'black body' is a hypothetical object or system which does not reflect or transmit any infrared energy incident upon it. All such radiation is absorbed and the black body re-radiates energy characteristic of its temperature only.
Data Source
Figure 1a~1c
Figure 2~3
Figure 4a~4c
AI summary
A method of measuring the temperature of a sheet material is provided. The sheet material is arranged such that it forms at least one side of a cavity so as to enhance the effective emissivity of the sheet material in the vicinity of the cavity. The method comprises: a) generating a thermal image of at least part of the inside of the cavity using a thermal imaging device to detect radiation emitted by the cavity, the thermal image comprising a plurality of pixels each having a pixel value representative of radiation emitted by a respective region of the cavity; b) identifying a first subset of the plurality of pixels whose pixel values meet predetermined criteria; c) using the identified first subset of pixels to determine a line on the thermal image representative of optimal emissivity enhancement in the cavity; and d) selecting a second subset of the plurality of pixels based on the determined line and generating a temperature profile along the determined line derived from the pixel values associated with each of the second subset of pixels.