Sensor Device Bright-Time FPN Correction via Ratio Coefficients
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Solution Overview
Problem
Existing signal processing methods for photodetectors struggle to effectively reduce fixed-pattern noise (FPN) across varying light intensities, particularly the bright-time FPN, which increases with incident light, leading to significant noise in measurement signals.
Innovation Solution
A sensor device with a controller that uses correction coefficients based on ratios of measured signals under different reference light intensities to correct measurement signals, effectively removing both additive and multiplicative FPN components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional signal processing methods (subtraction of reference signals) are used to reduce FPN, then dark-time FPN can be reduced, but bright-time FPN remains significant and increases with light intensity
Solution Approach 1:
The patent transforms the FPN correction approach by changing from simple signal subtraction to a ratio-based correction method. By dividing the detection signal by a reference signal (Sx/Rx) and applying correction coefficients, the system adapts to varying light intensities and effectively reduces bright-time FPN that conventional subtraction methods cannot handle.
Solution Approach 2:
The system uses measured reference signals under uniform reference light to generate correction coefficients that are fed back to correct the detection signals. This feedback mechanism allows the system to adaptively compensate for FPN variations across different operating conditions and light intensities.
2Measurement precision
If correction coefficients are determined using multiple reference lights of different intensities, then correction accuracy across varying illumination is improved, but processing complexity increases
Solution Approach 1:
The system performs preliminary measurements under multiple reference lights of different intensities to determine correction coefficients before actual detection. These pre-determined coefficients are stored and reused, avoiding the need for complex real-time calculations during detection while maintaining high correction accuracy across varying illumination conditions.
3Ease of operation
If simple subtraction of reference signals is used, then processing is simple, but correction effectiveness deteriorates under varying light intensities
Solution Approach 1:
The patent replaces the mechanical subtraction operation with a ratio-based correction system that uses division and multiplication. This substitution transforms the correction mechanism from a simple but ineffective subtraction to a more sophisticated ratio-based approach that maintains computational simplicity while significantly improving correction effectiveness under varying light intensities.
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 significantly reduces noise in measurement signals across a wide range of illumination intensities, improving the accuracy of photodetection signals by adaptively determining correction coefficients for each pixel.
Implementation Method 1
each of the plurality of pixels includes: a photodetector
Data Source
AI summary
A sensor device includes a plurality of pixels and a controller configured to correct measurement signals of the plurality of pixels. Each of the plurality of pixels includes a photodetector and a pixel circuit configured to output a signal from the photodetector. The controller is configured to acquire an unknown measured signal from one of the plurality of pixels, and correct the unknown measured signal of the one pixel with a correction coefficient which is based on ratios between values obtained from measured signals of the one pixel under a plurality of reference lights having different intensities and statistic values obtained from the values obtained from the measured signals of the plurality of pixels under a plurality of reference lights having different intensities.