Thermal Infrared Detector Pixel Grouping for Sensitivity
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Solution Overview
Problem
Miniaturization of thermal infrared detectors leads to decreased sensitivity and increased noise equivalent temperature difference (NETD) due to reduced infrared absorption area and increased thermal conductivity, as well as increased noise due to the volume decrease of bolometer material.
Innovation Solution
A thermal infrared detector with a pixel array comprising resistive infrared devices grouped in rows and columns, where at least two adjacent devices are connected in series, allowing for increased effective area and reduced thermal conductivity through a driving circuit that sequentially drives pixel groups to measure series resistance, thereby enhancing sensitivity and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thermal infrared detectors are miniaturized to enable portable applications, then device size is reduced and ease of manufacture is improved, but sensitivity decreases and noise equivalent temperature difference increases due to reduced infrared absorption area and increased thermal conductivity
Solution Approach 1:
The pixel array is divided into multiple pixel groups, where each group contains multiple pixels that are electrically connected in series. This segmentation allows the detector to maintain a compact physical form while achieving higher effective detection area through the combined response of multiple pixels within each group, thereby resolving the contradiction between miniaturization and sensitivity maintenance.
Solution Approach 2:
Multiple pixels within each pixel group are merged through electrical series connection to function as a single detection unit with enhanced sensitivity. The combined effective area of multiple pixels compensates for the reduced individual pixel size, allowing the miniaturized device to maintain adequate measurement precision despite the smaller overall detector dimensions.
2Device complexity
If pixel size is reduced for miniaturization, then device complexity is reduced and ease of manufacture is improved, but thermal conductivity increases leading to decreased temperature resolution
Solution Approach 1:
The detector is segmented into multiple pixel groups with selective electrical connections. This segmentation allows for reduced individual pixel size and simplified manufacturing while maintaining temperature resolution through the collective measurement capability of multiple pixels in series, which enhances the signal-to-noise ratio and compensates for increased thermal conductivity in smaller pixels.
3Volume of moving object
If bolometer material volume is decreased for miniaturization, then device size is reduced and ease of manufacture is improved, but noise increases due to reduced material volume
Solution Approach 1:
Multiple pixels with reduced bolometer material volume are merged through electrical series connection within pixel groups. The combined signal from multiple pixels increases the effective detection capability and improves the signal-to-noise ratio, compensating for the increased noise that would result from using smaller amounts of bolometer material in each individual 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
The solution increases the effective area of the sensor, improves sensitivity, and reduces thermal conductivity, resulting in improved temperature resolution and signal-to-noise ratio, addressing the challenges of miniaturization in thermal infrared detection.
Implementation Method 1
Each of the plurality of resistive infrared devices may include a bolometer
Implementation Method 2
convert heat generated within a device into an electrical signal by absorbing far-infrared (LWIR) energy emitted from an object to be measured
Implementation Method 3
at least two resistive infrared devices among the plurality of resistive infrared devices that are included in each of the at least two groups are connected in series
Data Source
AI summary
Provided is a thermal infrared detector including a thermal infrared sensor array including a plurality of resistive infrared devices that are provided in a plurality of rows and a plurality of columns, and a driving circuit configured to drive the thermal infrared sensor array, wherein at least two resistive infrared devices among the plurality of resistive infrared devices adjacent to each other in a row direction or a column direction are grouped together, wherein at least one resistive infrared device among the plurality of resistive infrared devices is shared by at least two groups, and wherein at least two resistive infrared devices among the plurality of resistive infrared devices that are included in each of the at least two groups are connected in series.