Shared Microlens Image Sensor for Omni-Directional Phase Detection Autofocus
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Solution Overview
Problem
Current image sensors face challenges in achieving multi-directional phase detection auto focus and full-size resolution recovery without the need for fine-tuning via contrast detection, especially when dealing with complex scenes featuring diagonal, horizontal, and vertical features.
Innovation Solution
The implementation of an image sensor architecture with a shared microlens between multiple subpixels, which enables dense and omni-directional phase difference calculations for instant autofocus, utilizing a phase detection pixel surrounded by subpixels with individual microlenses and color filters, allowing for accurate auto focus and depth mapping without contrast detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a shared microlens is used between multiple subpixels, then multi-directional phase detection auto focus capability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple microlens functions into a single shared microlens structure that serves multiple subpixels simultaneously. This shared microlens is positioned over a group of photodiodes (typically four) arranged in a 2x2 pattern, allowing phase detection in multiple directions without requiring separate microlens assemblies for each subpixel, thus improving versatility while managing complexity through functional integration.
Solution Approach 2:
The shared microlens is designed to perform multiple functions: it enables phase detection for autofocus in multiple directions (horizontal, vertical, diagonal), supports full-size resolution recovery, and works across different scene orientations. This multi-functional design allows a single component to replace what would traditionally require multiple specialized components.
2Measurement precision
If phase detection pixels with shared microlens are implemented, then instant autofocus accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The sensor array is segmented into repeating units, each containing a phase detection pixel with a shared microlens surrounded by subpixels. This modular segmentation allows the complex alignment requirements to be managed at the unit level rather than across the entire sensor, making manufacturing more controllable while maintaining high measurement precision through consistent repeating patterns.
Solution Approach 2:
The shared microlens is positioned at specific locations (over groups of photodiodes) rather than uniformly across the entire sensor. This localized approach concentrates the precision requirements to specific critical areas while allowing other regions to have relaxed tolerances, optimizing the balance between measurement precision and manufacturing feasibility.
3Use of energy by moving object
If individual microlenses are used for each subpixel, then light collection efficiency is improved, but device complexity and cost increase
Solution Approach 1:
Adjacent subpixels share a common microlens structure, reducing the total number of microlenses required compared to having individual microlenses for each subpixel. This merging approach maintains adequate light collection efficiency by directing light from multiple subpixels through a shared optical path to their respective photodiodes, while significantly reducing device complexity and manufacturing cost.
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 provides a single sensor solution for multi-directional phase detection auto focus and full-size resolution recovery, enabling instant and accurate autofocus capabilities across various scene features, enhancing image sensor performance and functionality.
Implementation Method 1
The image sensor includes an array of pixels having photosensitive elements (e.g., photodiodes) that absorb a portion of the incident image light and generate image charge upon absorption of the image light
Implementation Method 2
Each of the plurality of subpixels may include a subpixel color filter optically disposed between the photodiodes, other than the group of neighboring photodiodes, and a plurality of microlenses
Data Source
AI summary
An image sensor pixel includes a plurality of photodiodes, a shared microlens, and a plurality of microlenses. The plurality of photodiodes are arranged as a photodiode array with each of the plurality of photodiodes disposed within a semiconductor material. The shared microlens is optically aligned with a group of neighboring photodiodes included in the plurality of photodiodes. Each of the plurality of microlenses are optically aligned with an individual one of the plurality of photodiodes other than the group of neighboring photodiodes. The plurality of microlenses laterally surrounds the shared microlens.