Image Sensor Phase Detection Pixel Multiplexing
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Solution Overview
Problem
Image sensors face challenges in achieving quick and accurate auto-focusing while maintaining image quality, particularly in applications like automobiles and consumer electronics, where existing technologies struggle to balance phase detection and image sensing functions effectively.
Innovation Solution
The image sensor incorporates a pixel array with a combination of image sensing pixels and phase detection pixels, including shared phase detection pixels configured to generate phase signals for calculating phase differences, connected through a row driver and selection signal lines, allowing for efficient auto-focusing and high-resolution image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phase detection pixels are increased to improve auto-focusing speed and accuracy, then auto-focusing performance is improved, but image quality and resolution deteriorate
Solution Approach 1:
The patent implements dynamic pixel function switching where pixels can change their operational mode between image sensing and phase detection based on timing signals. During specific time periods, pixels function as phase detection pixels for rapid focusing, while at other times they function as image sensing pixels for high-quality capture. This temporal multiplexing allows the system to achieve both fast auto-focusing and high image quality without permanent pixel dedication.
Solution Approach 2:
The patent designs pixels with multi-functional capability, allowing each pixel to serve dual purposes: image sensing and phase detection. By equipping pixels with the ability to perform both functions through configurable circuitry and control mechanisms, the system eliminates the need for separate dedicated phase detection pixel arrays, thereby maintaining image quality while enabling rapid auto-focusing.
2Measurement precision
If dedicated phase detection pixels are used, then auto-focusing accuracy is improved, but pixel array complexity increases
Solution Approach 1:
The patent segments the pixel array into functional groups that can be dynamically assigned to different roles. Rather than creating a complex heterogeneous array with permanently dedicated phase detection pixels, the system divides pixels into groups that can be switched between image sensing and phase detection functions based on operational requirements, simplifying the overall array structure.
Solution Approach 2:
The patent employs periodic switching between image sensing and phase detection modes using time-division multiplexing. Control signals periodically activate phase detection functionality during specific time intervals while maintaining image sensing capability at other intervals. This periodic action allows accurate phase detection without requiring permanently complex pixel structures.
Data Source
AI summary
Provided is an image sensor including a pixel array which provides a plurality of pixels arranged in rows and columns. The plurality of pixels include: a plurality of image sensing pixels each including a plurality of image sensing sub pixels that include the same color filter; and a plurality of phase detection pixels each including at least one phase detection sub pixel which generates a phase signal for calculating a phase difference between images, wherein the plurality of image sensing sub pixels included in the same image sensing pixel are connected to one selection signal line and receive the same selection signal.