Image Sensor Light Shield Layout for PDAF Signal Compensation
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Solution Overview
Problem
Image sensors with phase-difference detection autofocus (PDAF) functions face image quality degradation due to signal differences caused by varying light transmission between phase-difference detection pixels and adjacent imaging pixels, affecting the amount of light received by peripheral pixels.
Innovation Solution
The image sensor incorporates a unit pixel array with phase-difference detection pixels, general pixels, and peripheral pixels, utilizing light shields of varying widths to adjust the light transmission and compensate for signal differences between peripheral and general pixels, ensuring consistent light reception and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If phase-difference detection pixels are used for autofocus, then autofocus functionality is improved, but signal difference between peripheral pixels and general pixels occurs causing image quality degradation
Solution Approach 1:
The patent applies local quality by configuring light shields with different widths in different regions of the pixel array. Specifically, light shields adjacent to phase-difference detection pixels have different widths compared to light shields in other regions, creating localized optical compensation that balances the light reception of peripheral pixels with general pixels while preserving autofocus functionality
Solution Approach 2:
The patent changes the physical parameter of light shield width to compensate for signal differences. By adjusting the width parameter of light shields in specific locations, the patent modifies the light transmission characteristics to balance signal levels between peripheral pixels and general pixels, thereby maintaining image quality alongside autofocus performance
2Manufacturing precision
If light shields of different widths are used to compensate signal differences, then image quality is improved, but device complexity increases
Solution Approach 1:
The patent segments the light shield structure into different width configurations based on their positional relationship with phase-difference detection pixels. This segmentation allows targeted compensation in specific regions while maintaining standard configurations in other areas, balancing image quality improvement with manageable device complexity
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 effectively compensates for signal differences between peripheral and general pixels, enhancing image quality by maintaining consistent light reception and improving autofocus functionality without altering the light-receiving rate of peripheral pixels.
Implementation Method 1
The first light shield is disposed in one of the general pixels and has a first width. The second light shield extends into the first peripheral pixel from a first area between the phase-difference detection pixels and the first peripheral pixel, and has a second width different from the first width.
Data Source
AI summary
An image sensor includes two or more phase-difference detection pixels disposed adjacent to each other, a plurality of general pixels spaced apart from the phase-difference detection pixels, first and second peripheral pixels, and first to third light shields. The first and second peripheral pixels are adjacent to the phase-difference detection pixels, and between the phase-difference detection pixels and the general pixels. The first light shield is disposed in one of the general pixels and has a first width. The second light shield extends into the first peripheral pixel from a first area between the phase-difference detection pixels and the first peripheral pixel, and has a second width different from the first width. The third light shield extends into the second peripheral pixel from a second area between the phase-difference detection pixels and the second peripheral pixel, and has a third width different from the first width.