Nano-Post Color Separation Lens Array for Filterless Image Sensors
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Solution Overview
Problem
Existing image sensors using color filters suffer from reduced light utilization efficiency due to absorption of light other than the corresponding color, leading to significant light loss.
Innovation Solution
An image sensor with a color separation lens array comprising nano-photonic structures that separate and converge light of different wavelengths without using color filters, utilizing nano-posts arranged in specific patterns to achieve efficient color separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are used to separate colors in an image sensor, then color separation is achieved, but light utilization efficiency is reduced due to absorption of non-corresponding light wavelengths
Solution Approach 1:
The patent extracts the color separation function from traditional color filters and implements it through a color separation lens array with nano-structures. This removes the absorbing color filter layer that causes light loss while maintaining color separation capability through refractive index differences in the nano-structures.
Solution Approach 2:
The patent replaces the mechanical/optical absorption mechanism of color filters with a refractive phase modulation mechanism using nano-structures. The color separation is achieved through phase differences introduced by nano-posts of varying heights, rather than through absorption, thereby eliminating light loss from absorption.
2Measurement precision
If nano-structures with sub-wavelength dimensions are used for color separation, then light can be separated by wavelength, but manufacturing precision becomes challenging due to small feature sizes
Solution Approach 1:
The patent segments the color separation function into multiple discrete height levels of nano-posts (first height for first wavelength, second height for second wavelength). This segmentation allows each nano-post height to be optimized for specific wavelength ranges, improving manufacturing feasibility while maintaining spectral separation performance.
Solution Approach 2:
The patent changes the geometric parameters of the nano-structures, specifically using discrete height values (first height and second height) for the nano-posts. By optimizing these height parameters, the patent achieves effective wavelength separation while making the structures manufacturable with current fabrication capabilities.
3Measurement precision
If multiple nano-photonic color sorting layers are used to improve color separation, then color separation efficiency increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies local quality by having different regions of the color separation lens array contain nano-posts with different height configurations. Specific pixel regions are assigned specific nano-post height patterns (first height or second height) to optimize color separation for those particular pixels, rather than using a uniform structure throughout.
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
Enhances light utilization efficiency by maximizing color separation efficiency while minimizing process errors during manufacturing.
Implementation Method 1
a color separation lens array (130) including a plurality of nano-posts (NP) arranged in a matrix pattern along first and second directions, wherein the color separation lens array separates and converges light of a first wavelength to a first pixel of the plurality of pixels and light of a second wavelength to a second pixel of the plurality of pixels
Data Source
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AI summary
Disclosed is an image sensor (1100) including a sensor substrate (110) including a plurality of light sensing cells (111, 112); a transparent spacer layer (120) provided over the sensor substrate; and a color separation lens array (130) provided over the spacer layer and including a plurality of nano-posts (NP1, NP2) configured to change a phase of incident light according to an incident location, wherein the plurality of nano-posts are arranged in a plurality of layers (LE1, LE2), wherein, from among the plurality of nano-posts, nano-posts having widths less than wc may be arranged only in any one layer of the plurality of layers. Also, wc may be greater than or equal to 80 nm and less than or equal to 200 nm. Therefore, the minimum width of the nano-posts provided in the color separation lens array may be increased, which is advantageous for a manufacturing process.