Image Sensor Phase Detection Shading Layers
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Solution Overview
Problem
Phase difference-based auto-focus systems in imaging devices are high-cost due to the requirement of a dedicated sensor and optical system, while contrast-based systems are slower and less accurate without a phase detecting sensor.
Innovation Solution
An image sensor with phase difference detecting pixels featuring a photoelectric conversion layer, color filter layer, and shading layers with specific light transmitting regions, allowing for improved accuracy and functionality in auto-focusing without the need for additional sensors or complex optical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference-based auto-focus systems are used, then auto-focusing accuracy and speed are improved, but system cost and complexity increase due to dedicated sensors and optical systems
Solution Approach 1:
The patent merges the phase difference detection function with the existing image sensor pixels by integrating shading layers that divide the pupil into multiple regions. This allows the image sensor to simultaneously perform both imaging and phase difference detection without requiring separate dedicated sensors, thereby reducing system complexity while maintaining detection accuracy
Solution Approach 2:
The patent segments the pupil aperture into multiple regions using shading layers positioned at different heights. By dividing the pupil into first and second regions with different shading configurations, the system enables phase difference detection through spatial segmentation of light paths, achieving accurate focus detection without additional optical components
2Device complexity
If contrast-based auto-focus systems are used, then system cost is reduced, but auto-focusing speed and accuracy decrease
Solution Approach 1:
The patent performs preliminary action by pre-positioning shading layers at specific heights during manufacturing to create predetermined light transmitting regions. This preliminary configuration enables rapid phase difference detection without requiring real-time complex calculations, achieving fast auto-focusing speeds comparable to optical methods while maintaining the simplicity of electronic processing
3Measurement precision
If shading layers are added to improve phase difference detection, then detection accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by implementing different shading layer configurations only in specific regions where phase difference detection is needed, rather than uniformly across the entire sensor. The first and second shading layers are positioned at different heights only in the pixel regions requiring pupil division, leaving other regions with simpler structures, thereby maintaining manufacturing ease while improving detection accuracy where required
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
Enhances the accuracy and cost-effectiveness of auto-focusing by integrating phase difference detecting pixels with shading layers that improve light transmission and reduce the distance between imaging lenses and shading masks, leading to improved phase difference detection and increased incident light, thus enhancing image characteristics in low illumination environments.
Implementation Method 1
a photoelectric conversion layer formed in a substrate
Implementation Method 2
a color filter layer formed over the photoelectric conversion layer; a first shading layer formed in the same plane as the color filter layer and defining a first light transmitting region
Data Source
AI summary
An image sensor includes: a plurality of pixels arranged in two dimensions, wherein at least one pixel among the pixels includes: a photoelectric conversion layer formed in a substrate; a color filter layer formed over the photoelectric conversion layer; a first shading layer formed in the same plane as the color filter layer and defining a first light transmitting region; and a second shading layer formed between the photoelectric conversion layer and the first shading layer and defining a second light transmitting region.