Shared Microlens Architecture for Phase Detection Autofocus
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Solution Overview
Problem
Current image sensors face limitations in achieving multi-directional phase detection auto focus and high dynamic range imaging while maintaining efficient power consumption and resolution, particularly in capturing detailed scenes with varying light conditions.
Innovation Solution
The implementation of a shared microlens architecture in image sensors, where each full color pixel includes subpixels optically aligned with a common color filter and microlens, enables multi-directional phase detection auto focus and high dynamic range imaging by varying integration times of photodiodes, allowing for enhanced depth mapping and focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shared microlens architecture is implemented to enable multi-directional phase detection auto focus, then focus accuracy and depth mapping capabilities are improved, but device complexity increases due to the need for precise optical alignment of multiple subpixels with a common microlens
Solution Approach 1:
Multiple subpixels (first, second, third, and fourth subpixels) share a common microlens, merging the optical path to enable multi-directional phase detection. This allows the system to achieve improved focus accuracy by comparing light paths from different subpixels while reducing the total number of microlenses required, thereby managing device complexity.
Solution Approach 2:
The pixel is divided into multiple subpixels (first, second, third, and fourth subpixels) with specific color filters arranged in a segmented pattern. This segmentation enables the extraction of phase information from different directions, improving focus accuracy while maintaining a manageable optical structure through systematic arrangement.
2Adaptability or versatility
If integration times of photodiodes are varied to achieve high dynamic range imaging, then dynamic range is improved, but measurement precision may be affected due to different exposure times
Solution Approach 1:
The integration time of photodiodes is made variable and adjustable, allowing the system to adapt to different light conditions. By dynamically changing integration times, the system can capture both bright and dark regions in a scene, achieving high dynamic range imaging while maintaining measurement precision through controlled exposure variations.
3Measurement precision
If more photodiodes are integrated into each pixel to enable multi-directional phase detection, then focus detection capability is improved, but power consumption increases
Solution Approach 1:
Each photodiode is designed to serve multiple functions: capturing image information for color imaging and simultaneously providing phase detection information for focus measurement. This multi-functionality allows the system to achieve improved phase detection capability without proportionally increasing power consumption, as the same hardware infrastructure serves dual purposes.
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 enables image sensors to provide multi-directional phase detection auto focus and high dynamic range imaging, improving focus accuracy and depth mapping capabilities while optimizing power consumption and resolution across varying light conditions.
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 color filters has a second lateral area greater than the first lateral area, and each of the plurality of microlenses has a third lateral area that is less than the second lateral area but greater than the first lateral area
Data Source
AI summary
An image sensor includes a plurality of photodiodes, a plurality of color filters, and a plurality of microlenses. The plurality of photodiodes are arranged as a photodiode array, each of the plurality of photodiodes disposed within respective portions of a semiconductor material with a first lateral area. The plurality of color filters are arranged as a color filter array optically aligned with the photodiode array. Each of the plurality of color filters having a second lateral area greater than the first lateral area. The plurality of microlenses are arranged as a microlens array optically aligned with the color filter array and the photodiode array. Each of the plurality of microlenses have a third later area greater than the first lateral area and less than the second lateral area.