Infrared Imaging Device Pixel Array Noise Compensation
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Solution Overview
Problem
Infrared imaging devices face challenges in reducing noise equivalent temperature difference (NETD) due to longitudinal streak noise caused by threshold voltage variations and noise components stored on signal lines during threshold voltage clamp processing.
Innovation Solution
The implementation of a semiconductor-based infrared imaging device with a matrix of pixels, including reference and detection pixels, utilizes a row selection circuit, column selection circuit, and signal processing units to clamp threshold voltages, amplify signals, and perform noise subtraction, effectively isolating infrared signal components from substrate temperature components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If threshold voltage clamp processing is performed to compensate for threshold voltage variation in amplification transistors, then measurement precision is improved, but longitudinal streak noise appears due to stored noise components on signal lines
Solution Approach 1:
The patent divides the pixel array into two distinct types: infrared detection pixels that detect infrared signals and reference pixels that do not detect infrared signals. This segmentation allows the reference pixels to serve as dedicated noise measurement units, separating the noise measurement function from the infrared detection function. By reading noise components from reference pixels and subtracting them from infrared detection pixel signals, the patent eliminates longitudinal streak noise while preserving threshold voltage compensation.
Solution Approach 2:
The patent introduces reference pixels as intermediary elements that act as mediators between the signal lines and the noise measurement process. These reference pixels are connected to the same signal lines as infrared detection pixels but do not contain infrared-absorbing structures, allowing them to capture only the noise components (including longitudinal streak noise) on the signal lines. The noise measured from these intermediary reference pixels is then used to cancel out the corresponding noise in the infrared detection signals.
2Device complexity
If uncooled infrared imaging device is used to eliminate cooling mechanism, then device complexity is reduced, but temperature resolution (NETD) increases due to noise and signal sensitivity limitations
Solution Approach 1:
The patent implements a self-service mechanism where the reference pixels automatically measure and provide noise component data for eliminating noise from infrared detection signals. The system uses its own internal reference pixels to generate the correction data needed for noise reduction, without requiring external calibration or additional complex noise measurement equipment. This self-service approach maintains the simplicity of uncooled devices while improving temperature resolution through active noise cancellation.
Solution Approach 2:
The patent establishes a feedback loop where noise components measured from reference pixels are fed back to the signal processing circuitry, which then subtracts these noise components from the infrared detection pixel signals. This feedback mechanism continuously compensates for noise including longitudinal streak noise, thereby improving the signal-to-noise ratio and reducing NETD while maintaining the simple uncooled device structure.
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 approach reduces longitudinal streak noise and enhances signal-to-noise ratio (S/N) while maintaining transistor threshold variation compensation, improving the temperature resolution and noise sensitivity of the infrared imaging device.
Implementation Method 1
an infrared absorption film to absorb the incident infrared rays and convert the incident infrared rays to heat
Implementation Method 2
converts a temperature change in a heat sensitive part generated by the converted feeble heat to an electric signal by using some thermoelectric conversion element
Data Source
AI summary
An infrared imaging device according to an embodiment includes: an imaging area formed on a semiconductor substrate, the imaging area having a plurality of pixels arranged in a matrix form, the plurality of pixels including a plurality of reference pixels arranged in at least one row and a plurality of infrared detection pixels arranged in remaining rows to detect incident infrared rays, each of the reference pixels having a first thermoelectric conversion element, each of the infrared detection pixel having a thermoelectric conversion unit, the thermoelectric conversion unit having an infrared absorption film to absorb the incident infrared rays and convert the incident infrared rays to heat and a second thermoelectric conversion element to convert the heat obtained by the conversion conducted by the infrared absorption film to an electric signal.