Temperature Sensor with Light-Absorbing Cavity for Accurate Food Monitoring
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Solution Overview
Problem
Existing temperature measurement arrangements in refrigerated display cabinets fail to accurately monitor the temperature of packaged food due to thermal insulation provided by packaging, which can lead to inaccuracies in cooling capacity adjustments, particularly under the influence of ambient light.
Innovation Solution
A temperature measurement arrangement with a temperature sensor and light sensor housed in a light-absorbing cavity that simulates the greenhouse effect of food packaging, allowing for accurate temperature determination by accounting for ambient light influence, using a solar cell or photodiode for light sensing and an evaluation device for signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature measurement is performed in a refrigerated cabinet using conventional temperature sensors, then the measurement structure is simple, but the measurement precision is insufficient due to thermal insulation by packaging and ambient light influence
Solution Approach 1:
The patent creates a simplified copy of food packaging using a transparent housing with a light-absorbing interior surface. This copy replicates the thermal insulation and light absorption characteristics of actual food packaging, allowing the temperature sensor to measure temperatures under identical conditions without requiring complex real packaging samples.
Solution Approach 2:
The transparent housing acts as an intermediary structure between the ambient environment and the temperature sensor. It allows ambient light to enter while the light-absorbing interior surface captures and retains thermal radiation, creating a controlled microenvironment that simulates packaged food conditions.
2Measurement precision
If conventional temperature sensors are used without light consideration, then the device is simple, but measurement results are falsified due to greenhouse effect from ambient light
Solution Approach 1:
The patent converts the harmful ambient light into a beneficial measurement factor by allowing it to pass through the transparent housing and be absorbed by the light-absorbing interior surface. This absorption creates a controlled thermal environment that actually improves measurement accuracy by replicating real packaging conditions.
Solution Approach 2:
The patent changes the optical parameters of the measurement environment by introducing a transparent housing that allows specific wavelengths of light to pass through while the light-absorbing surface converts that light energy into thermal energy, thereby changing the temperature parameters under measurement.
3Reliability
If temperature measurement does not account for packaging thermal insulation, then the measurement system is simple, but it cannot meet hygiene and food law requirements
Solution Approach 1:
The transparent housing with light-absorbing interior creates a simplified model of packaged food that replicates the thermal insulation properties. This copy allows the temperature sensor to measure the actual temperature conditions that packaged food experiences, ensuring compliance with food safety requirements.
Solution Approach 2:
The housing structure is pre-configured with light-absorbing materials and transparent sections before measurement begins. This preliminary arrangement ensures that when the temperature sensor operates, it automatically measures temperatures under conditions that simulate real packaging, preparing the measurement system in advance for accurate compliance assessment.
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 solution ensures accurate temperature monitoring, meeting hygiene and food law requirements by simulating the greenhouse effect and compensating for thermal radiation, thereby enabling reliable cooling capacity adjustments.
Implementation Method 1
The packaging material allows electromagnetic radiation of a certain spectral range (e.g. visible light, near infrared radiation and near ultraviolet radiation), but not to the same extent the emission of thermal radiation (infrared radiation). Also, the heat (temperature increase) generated by radiation absorption in the interior of the packaging cannot be released to the environment by convection.
Implementation Method 2
A so-called container packaging should be mentioned as an example, in which a dark-colored foam tub is covered with a transparent film (e.g. for meat or cheese). The goods in such packaging are exposed to a kind of greenhouse effect due to the ambient light that is inevitably present, i.e. the packaging material allows electromagnetic radiation of a certain spectral range
Implementation Method 3
A temperature sensor (19) is arranged within a cavity (17) of a closed housing unit (11)
Implementation Method 4
The temperature measuring arrangement according to the invention additionally comprises a light sensor which is preferably arranged in the cavity in which the temperature sensor is also arranged
Implementation Method 5
a solar cell or a photodiode is preferably used as the light sensor, since these components have a defined characteristic of the voltage as a function of the illuminance
Data Source
Figure 1a~1c
Figure 1d~1e
Figure 2a~2c
AI summary
The temperature measuring arrangement has a housing (11), which is closed by a light entrance window (13). The housing and the light entrance window define a hollow area (17), in which a temperature sensor (19) is arranged. A photosensor e.g. solar cell or photodiode, is arranged in the hollow area in such a manner that the photosensor is subjected to environment light, which penetrates into the hollow area through the light entrance window.