Imaging Sensor Pixel Segmentation for Low Light Color Imaging
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Solution Overview
Problem
Existing imaging sensors face significant challenges in capturing true color images under low light conditions due to limited signal-to-noise ratio (SNR), particularly in night vision applications, as silicon-based sensors with color filters suffer from reduced photon count and image quality degradation due to NIR blocking filters.
Innovation Solution
The proposed solution involves an imaging sensor with an array of pixels, each comprising a panchromatic and a sub-band pixel portion, where the sub-band pixel is independently addressable and filtered to capture a narrower spectral range within the panchromatic range, allowing for true color image acquisition with minimal loss in sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If color filters are applied to a silicon-based image sensor to capture true color images, then color information is obtained, but the signal-to-noise ratio and image quality are significantly degraded due to reduced photon count
Solution Approach 1:
Each pixel is divided into multiple pixel portions, with each portion having a different spectral response characteristic. Some portions are sensitive to visible light only, while others are sensitive to both visible and near-infrared light. This segmentation allows the sensor to capture color information from visible light while simultaneously capturing additional photons in the near-infrared range, thereby improving the signal-to-noise ratio without sacrificing color information.
2Loss of information
If an NIR blocking filter is used to block near-infrared light, then color accuracy is improved, but the overall light sensitivity and signal level are reduced
Solution Approach 1:
Different pixel portions within the same pixel have different spectral sensitivity characteristics. Some pixel portions have color filters that block NIR light for accurate color rendering, while other pixel portions lack NIR blocking and are sensitive to both visible and NIR light. This local differentiation allows the sensor to maintain color accuracy in specific regions while maximizing photon capture in other regions, thereby increasing overall signal level without compromising color accuracy.
3Reliability
If a panchromatic sensor is used to maximize light sensitivity, then signal-to-noise ratio is improved, but color information is lost
Solution Approach 1:
The imaging sensor is designed to perform multiple functions simultaneously through different pixel portions. Some pixel portions function as color-sensitive elements with visible light filters, while other portions function as high-sensitivity elements sensitive to both visible and near-infrared light. By combining the outputs from these different pixel portions, the sensor achieves both color information capture and high signal-to-noise ratio performance, making it universally applicable to both color imaging and low-light imaging requirements.
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 enables the acquisition of true color information with a high signal-to-noise ratio in low light conditions, maintaining sensitivity comparable to panchromatic imaging while reducing light loss by 25% or less, suitable for applications like night vision, surveillance, and automotive systems.
Implementation Method 1
The first pixel portion is responsive to light in a panchromatic spectral range
Implementation Method 2
The second pixel portion is responsive to light in a sub-band spectral range
Implementation Method 3
filtering light incident on the second pixel portion so that only light in a sub-band spectral range that is narrower than and contained within the panchromatic spectral range is incident on the photosensitive area of the second pixel portion
Data Source
AI summary
An imaging sensor for low light level color imaging includes an array of pixels. Each pixel has a first pixel portion that has a first photosensitive area and is responsive to light in a panchromatic spectral range and a second pixel portion that has a second photosensitive area and is responsive to light in a sub-band spectral range. The first photosensitive area is greater than the second photosensitive area and the sub-band spectral range is narrower than and contained within the panchromatic spectral range. The first and second pixel portions of each pixel are independently addressable. The imaging sensor is beneficial for applications requiring wide dynamic range, low light sensitivity and color discrimination, and enables improved object discrimination and scene interpretation.