Meta-Photodiode Image Sensor for Filter-Free Color Separation
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Solution Overview
Problem
Image sensors face reduced light utilization efficiency due to color filters and resolution limitations as pixel size decreases, leading to color separation issues and potential resolution degradation.
Innovation Solution
The design incorporates a pixel array with full-color imaging and autofocusing pixels, each equipped with meta-photodiodes for red, green, and blue wavelength bands, along with a lens array featuring micro and super lenses to enhance light collection and separation without the need for color filters, allowing for efficient color detection and autofocusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a color filter is used to sense color, then color detection is enabled, but light utilization efficiency is reduced
Solution Approach 1:
The patent removes the color filter layer from the image sensor structure. Instead of using a color filter to detect color, the invention uses meta-photodiodes with selective wavelength absorption capabilities built into the photodetector layer itself, thereby eliminating the harmful light absorption by color filters and improving light utilization efficiency
Solution Approach 2:
The patent replaces the optical filtering mechanism (color filter) with a photodetector-based wavelength selection mechanism (meta-photodiodes). The meta-photodiodes use nanoscale resonant structures to selectively absorb specific wavelengths, substituting the mechanical/optical filtering approach with an electromagnetic resonance-based detection approach
2Productivity
If pixel size is decreased to increase resolution, then more pixels can be packed, but color separation function is limited
Solution Approach 1:
The patent changes the operational parameters of the photodetectors by introducing meta-photodiodes with wavelength-selective absorption characteristics. Each meta-photodiode is designed to resonate and absorb specific wavelength bands (red, green, blue), enabling color separation at the photodetector level rather than relying on spatial color filter arrays, thus maintaining color separation capability even at reduced pixel sizes
Solution Approach 2:
The patent transitions from spatial color separation (using color filter arrays in the optical path) to spectral color separation (using wavelength-selective absorption in the photodetector layer). This dimensional shift from spatial filtering to spectral filtering at the detector level enables full-color detection in each pixel without requiring large pixel areas for multiple color filters
3Difficulty of detecting and measuring
If energy is divided into R, G, and B effective areas, then color detection is achieved, but resolution degradation occurs due to under-sampling
Solution Approach 1:
The patent merges the color detection function and the resolution function into a single integrated approach. By using meta-photodiodes that can detect multiple wavelengths simultaneously within each pixel, the invention combines what were previously separate functions (color filtering and high-resolution detection) into one unified detection mechanism, eliminating the need for color filter arrays that cause under-sampling and resolution loss
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 configuration improves light utilization efficiency and maintains high resolution by enabling effective color separation and autofocusing without the limitations of traditional color filters, reducing the occurrence of image artifacts and enhancing overall image quality.
Implementation Method 1
a first red meta-photodiode configured to selectively absorb light of a red wavelength band, a first green meta-photodiode configured to selectively absorb light of a green wavelength band, and a first blue meta-photodiode configured to selectively absorb light of a blue wavelength band
Implementation Method 2
a lens array including a plurality of micro lenses facing the plurality of imaging pixels, respectively, and one or more super lenses facing the plurality of autofocusing pixels
Implementation Method 3
Each of the plurality of micro lenses and the one or more super lenses included in the lens array may be a refractive lens having a curved surface
Data Source
AI summary
Provided is an image sensor including a pixel array including a plurality of imaging pixels and a plurality of autofocusing pixels, and a lens array including a plurality of micro lenses facing the plurality of imaging pixels, respectively, and one or more super lenses facing the plurality of autofocusing pixels, wherein each imaging pixel of the plurality of imaging pixels includes a first red meta-photodiode configured to selectively absorb light of a red wavelength band, a first green meta-photodiode configured to selectively absorb light of a green wavelength band, and a first blue meta-photodiode configured to selectively absorb light of a blue wavelength band.