Thermopile Infrared Sensor Array With Integrated Signal Processing
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Solution Overview
Problem
High-resolution thermopile infrared sensor arrays face challenges with low signal-to-noise ratio and increased noise bandwidth due to small pixel sizes and limited integration of signal processing channels on the chip, leading to reduced thermal resolution and power consumption issues.
Innovation Solution
The integration of multiple parallel signal processing channels with low-noise preamplifiers and high-resolution analog/digital converters on the sensor chip, along with a signal multiplexer and low-pass filters, to reduce noise bandwidth and power consumption while maintaining high thermal and geometric resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of pixels is increased to achieve high-resolution sensor arrays, then geometric resolution is improved, but the signal voltage decreases proportionally
Solution Approach 1:
The patent divides the sensor array into multiple independent signal processing channels, each handling a subset of pixels. This segmentation allows each channel to process fewer pixels with dedicated low-pass filters, reducing the noise bandwidth for each channel while maintaining high overall geometric resolution through the increased pixel count.
2Measurement precision
If high gain factors are used to amplify low signal voltages, then signal strength is improved, but the signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies low-pass filtering before signal amplification to pre-reduce the noise bandwidth. By limiting the frequency range of the signal before it enters the high-gain amplifier, the noise component is reduced in advance, allowing the amplifier to boost the signal without proportionally amplifying the noise, thus preserving the signal-to-noise ratio.
3Measurement precision
If traditional high gain amplifiers are used to amplify signals, then signal voltage is improved, but power consumption and self-heating increase
Solution Approach 1:
The patent segments the pixel array into multiple groups, each served by its own signal processing channel with dedicated low-pass filter and amplifier. This segmentation allows each amplifier to operate at lower power levels while collectively serving all pixels, reducing the total power consumption compared to a single high-power amplifier serving all pixels.
Solution Approach 2:
The patent employs cyclic multiplexing where signal processing channels are activated in periodic cycles rather than continuously. Each channel processes signals from its assigned pixels during its active cycle, then enters a low-power state. This periodic operation significantly reduces average power consumption while maintaining the ability to process all pixel signals.
4Device complexity
If fewer preamplifiers are integrated on the chip to save space, then device complexity is reduced, but noise bandwidth increases
Solution Approach 1:
The patent designs signal processing channels that can be selectively activated and deactivated based on the current measurement needs. Each channel is multi-functional, capable of processing signals from multiple different pixel groups at different times. This universality allows the system to use fewer physical preamplifiers while still providing dedicated noise filtering for each pixel group when needed, maintaining low noise bandwidth without requiring a preamplifier for every single pixel.
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 enhances thermal resolution by up to 8 times and reduces noise bandwidth, achieving better signal-to-noise ratio and lower power loss, allowing for more efficient processing of thermopile sensor signals with minimal space and power requirements.
Implementation Method 1
The thermopiles have so-called 'hot' contacts on a progressively smaller infrared receiving area and so-called 'cold' contacts on a heat sink at the edge of each pixel. The signal voltage generated by the thermopile depends directly on the achievable temperature difference between the 'hot' and 'cold' contacts.
Data Source
Figure 1
Figure 2~3
Figure 4a~4b
AI summary
The invention relates to a high-resolution thermopile infrared sensor array having monolithically integrated signal processing and a plurality of parallel signal processing channels for the signals from pixels of a sensor array, and to a digital port for the serial output of the pixel signals, wherein the sensor array is located on one or more sensor chips. The aim of the invention is to specify a thermal piled infrared sensor array having monolithically integrated signal processing and a plurality of parallel signal processing channels which, while having the lowest power loss, has a high integration density and which at the same time has high thermal and geometric resolution. Said aim is achieved in that each signal processing channel (K1... KN) has at least one analogue/digital converter (ADC), and in that each signal processing channel (K1...KN) is assigned a memory region in a memory (RAM) for storing the signals from the pixels (SE).