Image Sensor Phase Difference Pixels with Antireflection Layers
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Solution Overview
Problem
Current image sensors with autofocus functions face challenges in accurately detecting phase differences for focusing, particularly in varying light conditions, due to limitations in the design of phase difference detection pixels and the integration of antireflection layers, which can degrade optical sensitivity.
Innovation Solution
The design incorporates phase difference detection pixels with antireflection layers covering microlenses in specific light receiving regions, allowing for improved light sensitivity and accurate phase difference detection by adjusting the position of the lens based on calculated defocus values from signals generated by first and second phase difference detection pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an antireflection layer is integrated over the microlens in phase difference detection pixels, then light sensitivity is improved, but manufacturing precision and optical performance are degraded due to reflection and sensitivity loss
Solution Approach 1:
The patent applies local quality by selectively positioning the antireflection layer only in specific regions where it provides benefit, rather than uniformly across the entire microlens. The antireflection layer is placed in regions that do not interfere with the optical path, thereby improving light sensitivity in those areas while preserving optical performance in critical regions.
Solution Approach 2:
The microlens surface is segmented into different functional zones: regions with antireflection layers for enhanced light sensitivity and regions without antireflection layers for maintaining optical performance. This segmentation allows the system to simultaneously achieve both improved light sensitivity and preserved optical performance in different areas of the same pixel structure.
2Measurement precision
If phase difference detection pixels are designed with shifted light receiving regions, then autofocus accuracy is improved, but device complexity increases due to additional structural elements
Solution Approach 1:
The patent merges multiple functions into the phase difference detection pixel structure by integrating the shifted light receiving regions, microlenses, and antireflection layers into a unified pixel design. This combination achieves accurate phase difference detection for autofocus while reducing overall device complexity compared to having separate components for each function.
Solution Approach 2:
The phase difference detection pixels are designed with multi-functionality, serving both as imaging pixels and as autofocus detection pixels. The shifted light receiving regions enable these pixels to perform phase difference detection for autofocus accuracy, while the same structure also maintains imaging capabilities, thereby reducing the need for separate dedicated autofocus pixels and lowering overall 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 enhances autofocus performance by maintaining optical sensitivity and improving accuracy in focusing, even in low illumination conditions, by selectively using main and sub patterns in phase difference detection signals to adjust the lens position effectively.
Implementation Method 1
a plurality of microlenses arranged over the plurality of photoelectric conversion elements to focus incident light on the plurality of photoelectric conversion elements
Implementation Method 2
at least one antireflection layer structured to cover another portion of the at least one of the microlenses to reduce a reflection of light at the at least one of the microlenses
Implementation Method 3
a plurality of photoelectric conversion elements structured to capture optical signals and detect a phase difference in the optical signals
Data Source
AI summary
The technology disclosed in this patent document can be implemented in embodiments to provide an image sensor that includes a first phase difference detection pixel having a light receiving region shifted by a first displacement distance, and a second phase difference detection pixel having a light receiving region shifted by a second displacement distance in a second direction opposite to the first direction, wherein the first and second phase difference detection pixels are structured to detect phase difference information of incident light for controlling focusing of incident light at the imaging pixels for image sensing by the imaging pixels, and each of the first phase difference detection pixel and the second phase difference detection pixel includes an antireflection layer structured to partially cover a microlens, in the light receiving region.