Image Sensor Mixed Pixel Array Light Sensitivity
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Solution Overview
Problem
Existing electronic image sensors with two-dimensional arrays of pixels suffer from reduced light sensitivity due to the use of color filters, limiting their ability to capture high-quality images in low-light conditions or with moving objects, and existing solutions either increase noise or require complex and costly systems.
Innovation Solution
A two-dimensional image sensor with a pattern of intermixed color and panchromatic pixels, where panchromatic pixels have wider spectral sensitivity, allowing for improved light sensitivity and noise reduction by adjusting the sensitivity of color pixels to match panchromatic pixels, and employing various patterns and interpolation methods to produce full-color images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If color filters are applied to pixels to enable color image capture, then color information is obtained, but light sensitivity is reduced
Solution Approach 1:
The pixel array is segmented into multiple types of pixels including color-filtered pixels (red, green, blue) and panchromatic pixels without color filters. This segmentation allows different regions to serve different functions: color pixels capture chromatic information while panchromatic pixels maximize light sensitivity, resolving the contradiction between obtaining color information and maintaining light sensitivity.
Solution Approach 2:
Different regions of the pixel array are assigned different optical properties. Specifically, certain pixel locations are equipped with color filters to capture color information, while other locations use panchromatic pixels without filters to maximize light sensitivity. This local differentiation allows the system to optimize both color capture and light sensitivity in different spatial locations.
2Illumination intensity
If panchromatic pixels are added to improve light sensitivity, then noise is reduced, but device complexity increases
Solution Approach 1:
The pixel array is organized into repeating units that contain both color-filtered pixels and panchromatic pixels. This segmentation into manageable repeating patterns simplifies the overall design complexity while still providing the benefits of mixed pixel types. The regular structure makes manufacturing and data processing more tractable compared to irregular arrangements.
Solution Approach 2:
Rather than making all pixels panchromatic (which would maximize sensitivity but eliminate color information), the invention applies panchromatic pixels to a partial extent within the array. This partial application achieves improved light sensitivity and reduced noise while maintaining color capture capabilities through the remaining color-filtered pixels, thus avoiding excessive complexity.
3Illumination intensity
If all pixels are made monochrome to maximize sensitivity, then light sensitivity is improved, but color image capture is lost
Solution Approach 1:
The pixel array is segmented into multiple functional regions including color-filtered pixels (red, green, blue) and panchromatic pixels. This segmentation ensures that color information is captured by the color-filtered pixels while light sensitivity is maximized by the panchromatic pixels, resolving the contradiction between maintaining color information and improving light sensitivity.
Solution Approach 2:
The pixel array is designed to perform multiple functions simultaneously: color capture, high-sensitivity luminance capture, and noise reduction. By incorporating both color-filtered and panchromatic pixels within the same array, the system achieves multi-functionality that would require separate systems otherwise, maintaining color information while improving light sensitivity.
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 enhances light sensitivity, enabling high-quality image capture in low-light conditions and reducing noise, while maintaining cost-effectiveness and simplicity compared to previous solutions.
Implementation Method 1
a two-dimensional array of color and panchromatic pixels. Each pixel includes a photodetector and associated circuitry
Data Source
Figure 1
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Figure 4A~5
AI summary
An image sensor for capturing a color image is disclosed having a two-dimensional array having first and second groups of pixels wherein pixels from the first group of pixels have narrower spectral photoresponses than pixels from the second group of pixels and wherein the first group of pixels has individual pixels that have spectral photoresponses that correspond to a set of at least two colors. Further, the placement of the first and second groups of pixels defines a pattern that has a minimal repeating unit including at least twelve pixels. The minimal repeating unit has a plurality of cells wherein each cell has at least two pixels representing a specific color selected from the first group of pixels and a plurality of pixels selected from the second group of pixels (panchromatic = white pixels) arranged to permit the reproduction of a captured color image under different lighting conditions .