Prismatic De-multiplexing in Backside Illuminated Image Sensors
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Solution Overview
Problem
As image sensors and their pixels continue to shrink, efficiently capturing photonically generated charges becomes a challenge, affecting the quality of electronic images, especially in capturing light of different colors without significant loss or blurring.
Innovation Solution
The implementation of a backside illuminated imaging sensor with a prismatic de-multiplexing system, where a refraction element with a high index of refraction is used to refract light into different color components, allowing each pixel to capture specific colors efficiently, reducing the need for color filters and enhancing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If image sensors and pixels are shrunk to reduce size, then device compactness is improved, but light capture efficiency deteriorates
Solution Approach 1:
The sensor surface is divided into multiple pixel elements, each further segmented into color-filtered sub-pixels (red, green, blue). This segmentation allows each sub-pixel to capture specific wavelength ranges efficiently, improving overall light capture efficiency even as the total sensor size decreases.
Solution Approach 2:
Different regions of the sensor (individual pixels and sub-pixels) are assigned different optical properties through color filters. Each sub-pixel is optimized to capture specific color wavelengths, creating local quality variations that enhance overall light capture efficiency in compact form factors.
2Measurement precision
If color filters are used to capture different colors, then color discrimination is improved, but light loss increases
Solution Approach 1:
Instead of using complete color filters that block most wavelengths, the invention uses color filters that selectively transmit specific wavelength ranges (red, green, blue). This partial action approach allows sufficient color discrimination while minimizing light loss by permitting relevant wavelengths to pass through to the photodetectors.
3Area of moving object
If pixel size is reduced, then sensor compactness is improved, but charge capture efficiency deteriorates
Solution Approach 1:
Each pixel is segmented into multiple color-filtered sub-pixels, allowing the total pixel area to be divided into specialized regions. This segmentation enables each sub-pixel to capture specific color wavelengths more efficiently, maintaining charge capture efficiency even as overall pixel area decreases.
Solution Approach 2:
Different sub-regions within each pixel are assigned different color filter properties, creating local quality variations. This allows each sub-pixel to optimize charge capture for its specific wavelength range, improving overall charge capture efficiency in smaller pixels.
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 improves quantum efficiency by allowing each pixel to capture specific colors effectively, reducing light loss and blurring, and maintaining image quality even in smaller sensor sizes.
Implementation Method 1
a refraction element with a high index of refraction is used to refract light into different color components
Data Source
AI summary
An image sensor includes a first imaging pixel for a first color having a photosensitive region disposed within a substrate of the image sensor and a second imaging pixel for a second color that is different from the first color having a photosensitive region disposed within the substrate. A refraction element disposed adjacent to the substrate, so that the refraction element refracts light of the first color to the photosensitive region of the first imaging pixel and refracts light of the second color to the photosensitive region of the second imaging pixel.