Thermopile Sensor With Electromagnetic Blocker for Ambient Radiation Rejection
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Solution Overview
Problem
Thermopile sensors face challenges in accurately measuring object temperature due to the detection of electromagnetic radiation from both the object of interest and other unwanted sources, leading to voltage outputs that include ambient temperature signals, which can interfere with precise temperature measurements.
Innovation Solution
A sensor package is designed with a thermopile sensor and a reference thermopile sensor, where the latter is shielded from electromagnetic radiation using an electromagnetic blocker, allowing for the subtraction of ambient signals and enabling accurate temperature measurement by isolating the radiation from the object of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermopile sensor is used to measure object temperature, then temperature measurement capability is provided, but electromagnetic radiation from unwanted sources and ambient temperature signals interfere with measurement precision
Solution Approach 1:
The sensor system is segmented into multiple independent thermopile sensors: a primary thermopile sensor for detecting object radiation and a reference thermopile sensor for detecting ambient radiation. This segmentation allows independent optimization of each sensor's function and enables separate processing of the measurement signals to eliminate interference.
Solution Approach 2:
An electromagnetic blocker is introduced as an intermediary component between the reference thermopile sensor and the external environment. This blocker selectively allows infrared radiation from the object to reach the primary sensor while blocking electromagnetic radiation from unwanted sources from reaching the reference sensor, thereby isolating the reference measurement from interference.
2Measurement precision
If a reference thermopile sensor is added to subtract ambient signals, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The reference thermopile sensor and primary thermopile sensor are merged into a single integrated sensor package with shared structural components including the substrate, lid assembly, and electromagnetic blocker. This merging reduces the overall complexity compared to having separate reference and measurement systems, while still enabling accurate ambient signal subtraction through the combined sensor outputs.
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 allows for precise temperature measurement by isolating the object's radiation from ambient radiation, improving the accuracy of thermopile sensors in applications like non-contact temperature measurement.
Implementation Method 1
These sensors may utilize several thermocouples to generate an output voltage proportional to a local temperature difference
Implementation Method 2
The lid assembly includes a transparent structure that passes electromagnetic radiation occurring in a limited spectrum of wavelengths (e g., infrared radiation [IR])
Data Source
AI summary
A sensor package having a thermopile sensor and a reference thermopile sensor disposed therein. In one or more implementations, the sensor package includes a substrate, a thermopile sensor disposed over the substrate, a reference thermopile sensor disposed over the substrate, and a lid assembly disposed over the thermopile sensor and the reference thermopile sensor. The lid assembly includes a transparent structure that passes electromagnetic radiation occurring in a limited spectrum of wavelengths and an electromagnetic blocker disposed over the lid assembly. The electromagnetic blocker defines an aperture over the thermopile sensor such that at least a portion of the electromagnetic blocker is positioned over the reference thermopile sensor. The electromagnetic blocker is configured to at least substantially block the electromagnetic radiation occurring in a limited spectrum of wavelengths from reaching the reference thermopile sensor.