Infrared Sensor Housing with External Window Fixation
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Solution Overview
Problem
Infrared sensors, particularly thermopile-based temperature measurement systems, are susceptible to fluctuations in ambient temperature, which interfere with accurate temperature measurements by influencing the electrical output signal and indirect temperature measurement.
Innovation Solution
The sensor design includes a housing with a radiation inlet window made of a radiation-transmissible material, such as a Fresnel lens or phase plate, fixed externally to prevent fixation material from entering the field of view and emitting interfering radiation, and inner surfaces with low emissivity or concave geometry to minimize ambient radiation reflection onto the sensor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor element is thermally isolated from the housing to improve temperature measurement accuracy, then the sensor becomes more sensitive to ambient temperature changes
Solution Approach 1:
The patent introduces a membrane as an intermediary structure between the sensor element and the housing. This membrane provides thermal isolation while maintaining mechanical support, acting as a mediator that prevents direct thermal contact between the sensor and the housing, thereby reducing the harmful effect of ambient temperature changes on measurement accuracy
Solution Approach 2:
The patent employs a thin membrane structure to thermally isolate the sensor element from the housing. This flexible thin film provides adequate thermal barrier properties while maintaining the structural integrity and positioning of the sensor, effectively reducing heat transfer from the ambient environment to the sensor element
2Strength
If fixation material is used to secure the radiation inlet window, then the window is firmly attached, but the fixation material emits interfering radiation into the sensor's field of view
Solution Approach 1:
The patent extracts the harmful fixation material from the sensor's field of view by positioning the radiation inlet window such that the fixation material is located outside the detection area. This separation removes the source of interfering radiation from the measurement path while maintaining the structural attachment of the window
Solution Approach 2:
The patent applies different properties to different parts of the system: the radiation inlet window maintains high transmissivity in the measurement area, while the fixation material located outside the field of view can have different properties without affecting the measurement. This local differentiation allows the fixation material to provide strong attachment without generating harmful radiation in the detection path
3Measurement precision
If inner surfaces have high emissivity to reduce ambient radiation reflection, then measurement accuracy improves, but the sensor becomes more sensitive to temperature changes of the housing
Solution Approach 1:
The patent modifies the emissivity parameter of the inner surfaces by applying low-emissivity coatings. This parameter change reduces the reflection of ambient thermal radiation from the housing walls while maintaining the ability to detect incoming infrared radiation, thereby improving measurement accuracy without excessive sensitivity to housing temperature variations
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 configuration reduces the impact of ambient temperature changes and interfering radiation on the measurement, enhancing the sensor's insensitivity to temperature fluctuations and improving the accuracy of infrared radiation and temperature measurements.
Implementation Method 1
a radiation inlet window (35) closed by a material transmissible for the radiation to be detected and frequently having imaging properties (lens, Fresnel lens, lattice, phase plate)
Implementation Method 2
They may be thermopiles or pyrodetectors or bolometers
Implementation Method 3
infrared sensors, particularly thermopile-based temperature measurement systems, are susceptible to fluctuations in ambient temperature
Implementation Method 4
inner surfaces with low emissivity or concave geometry to minimize ambient radiation reflection onto the sensor element
Implementation Method 5
The temperature difference between the cold and the hot end results in a measurable voltage difference
Data Source
AI summary
A sensor for detecting electromagnetic radiation comprises a sensor element, a housing in which the sensor element is disposed, and a radiation inlet window provided in the housing and closed by a material transmissible for the radiation to be detected. The transmissible material is fixed to the housing by fixation means not disposed in the field of view of the sensor element.