Image Sensor Pixel Layout for Faster, More Accurate Autofocus
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Solution Overview
Problem
Current image sensors face challenges in simultaneously optimizing the performance of normal pixels and auto-focus (AF) pixels, requiring improved design to enhance image capture speed and accuracy.
Innovation Solution
The image sensor design includes a pixel array with normal pixels and AF pixels arranged in specific configurations, where AF pixels have multiple photodiodes and larger sizes compared to normal pixels, allowing for enhanced focus detection and image capture capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AF pixels are designed with multiple photodiodes and larger size, then auto-focus detection precision is improved, but normal pixel performance is compromised
Solution Approach 1:
The pixel array is segmented into distinct normal pixels and AF pixels with different structures. Normal pixels use single photodiodes optimized for image capture, while AF pixels use multiple photodiodes (e.g., 2×2 or 3×3 arrays) optimized for focus detection. This segmentation allows each pixel type to be independently optimized without compromising the other.
Solution Approach 2:
Different regions of the pixel array are assigned different structural qualities. AF pixels in specific regions have larger sizes and multiple photodiodes for enhanced focus detection, while normal pixels in other regions maintain standard sizes and single photodiodes for optimal image capture. This local differentiation resolves the contradiction by applying appropriate structures to appropriate locations.
2Measurement precision
If AF pixels are made larger with multiple photodiodes, then focus detection capability is enhanced, but pixel array density is reduced
Solution Approach 1:
The pixel array is divided into normal pixels and AF pixels, with AF pixels occupying only specific regions (e.g., certain rows or columns). This segmentation ensures that while AF pixels have larger sizes for better focus detection, the overall pixel array density is maintained by keeping normal pixels at standard sizes in the remaining areas.
Solution Approach 2:
Instead of increasing AF pixel size uniformly across the entire array, the patent uses selective placement in specific dimensions or regions of the array. For example, AF pixels may be placed in alternating rows or columns, or in specific blocks, allowing large AF pixels to coexist with high overall density through strategic spatial arrangement.
3Adaptability or versatility
If normal pixels and AF pixels are integrated in the same array, then image capture and auto-focus functions are combined, but device complexity increases
Solution Approach 1:
The pixel array is segmented into normal pixels with single photodiodes for image capture and AF pixels with multiple photodiodes for focus detection. Each segment has a dedicated function, simplifying the design within each segment while achieving overall functional integration through their coexistence in the same array.
Solution Approach 2:
The pixel array structure is designed to serve multiple functions through different pixel types. Normal pixels handle image capture while AF pixels handle focus detection, and both can operate within the same array framework. This multi-functionality is achieved through a unified array structure that accommodates different pixel configurations without requiring separate systems.
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 enables improved auto-focus functionality and image quality by optimizing the performance of both normal and AF pixels, facilitating faster and more accurate image capture.
Implementation Method 1
each pixel may include at least one photodiode
Data Source
AI summary
An image sensor includes; a pixel array including pixels arranged in a first direction and a second direction, wherein the pixels includes a first normal pixel and a first auto focus (AF) pixel adjacent in the first direction, and a second AF pixel and a second normal pixel adjacent in the first direction. Each of the first AF pixel and the second AF pixel includes at least two photodiodes, each of the first normal pixel and the second normal pixel has a quadrangular shape, a first length of the first AF pixel in the first direction is greater than a first length of the first normal pixel in the first direction, and a first length of the second AF pixel in the first direction is greater than a first length of the second normal pixel in the first direction.