Microlens Refractive Index Layout for PDAF Pixel Crosstalk
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Solution Overview
Problem
Image sensing devices face challenges in preventing crosstalk between adjacent pixels, particularly in phase detection autofocus (PDAF) pixels, which affects image quality and signal-to-noise ratio.
Innovation Solution
The implementation of microlenses with different refractive indexes, where a high-refractive-index lens is used for PDAF pixels to minimize crosstalk by directing incident light efficiently and reducing light diffusion into adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lens with uniform refractive index is used for all pixels, then the device structure is simple and easy to manufacture, but crosstalk occurs between adjacent pixels reducing image quality
Solution Approach 1:
The patent applies local quality by assigning different refractive indexes to lenses based on their specific function and position. PDAF pixels receive high-refractive-index lenses for precise phase detection, while other pixels use conventional lenses. This localized differentiation eliminates crosstalk in critical areas without requiring all lenses to be complex, thus improving image quality while controlling overall device complexity.
Solution Approach 2:
The patent segments the pixel array into different functional regions: PDAF pixels for phase detection and other pixels for standard imaging. By segmenting the lens array accordingly with high-refractive-index lenses only for PDAF pixels, the solution addresses crosstalk where it matters most while maintaining manufacturing efficiency for the majority of pixels.
2Reliability
If lenses with different refractive indexes are used for different pixels, then crosstalk between adjacent pixels is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The patent implements local quality by applying high-refractive-index lenses selectively only to PDAF pixels where crosstalk prevention is critical for phase detection accuracy. This targeted approach improves signal-to-noise ratio in the most sensitive areas while limiting the manufacturing complexity increase to a small subset of pixels, making the overall fabrication process more manageable.
3Reliability
If a high-refractive-index lens is used for PDAF pixels, then light diffusion into adjacent pixels is reduced, but the lens fabrication precision requirements increase
Solution Approach 1:
The patent applies high-refractive-index lenses specifically to PDAF pixels where crosstalk prevention is most critical for accurate phase detection. This localized application maximizes crosstalk prevention effectiveness in the most sensitive regions while concentrating manufacturing precision requirements on a limited number of lenses rather than all pixels, making the precision demands more manageable.
Solution Approach 2:
By segmenting the pixel array into PDAF and non-PDAF regions, the patent concentrates the high-precision manufacturing requirements for high-refractive-index lenses only in the PDAF segment. This segmentation allows the majority of pixels to use standard lenses with relaxed precision tolerances, thereby reducing overall manufacturing precision burden while maintaining effective crosstalk prevention where needed.
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 solution effectively prevents crosstalk and enhances light gathering power, improving image quality and signal-to-noise ratio by using a high-refractive-index lens for PDAF pixels, thereby reducing diffracted light introduction into adjacent pixels.
Implementation Method 1
a high-refractive-index lens is used for PDAF pixels to minimize crosstalk by directing incident light efficiently and reducing light diffusion into adjacent pixels
Data Source
AI summary
An image sensing device for preventing a crosstalk path is disclosed. The image sensing device includes a substrate including a plurality of photoelectric conversion elements, each of which generates and accumulates photocharges corresponding to incident light and a plurality of lenses disposed over the substrate, and arranged to receive the incident light and to direct received incident light to the plurality of photoelectric conversion elements, wherein the plurality of lenses includes a first lens and a second lens that are arranged to contact each other and have different refractive indexes from each other.