Image Sensor Focus Pixels with Shifted Openings for Defocus Detection
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Solution Overview
Problem
Conventional image sensors with focus detecting pixels arranged for phase difference method struggle with accurate focus detection in largely-defocused states, especially with fast photographing lenses, leading to longer autofocus times and compromised image quality.
Innovation Solution
The image sensor incorporates multiple focus detecting pixels with shifted opening positions and varying light shielding ratios, arranged in a specific pattern across the imaging plane, including first, second, third, and fourth focus detecting pixels, to enhance focus detection accuracy and image quality even in largely-defocused conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light shielding patterns are arranged for focus detecting pixels, then focus detection in largely-defocused states is improved, but image quality performance deteriorates
Solution Approach 1:
The patent applies dynamics by making the light shielding pattern configurable or switchable rather than fixed. The system can dynamically select or adjust which light shielding pattern is active based on the current focus state or detection needs. This dynamic capability allows the system to optimize for either near-focus or large-defocus detection as needed, while maintaining image quality by not permanently compromising any pixel's function.
Solution Approach 2:
The patent changes parameters of the light shielding patterns, such as opening ratios, opening positions, or shielding densities, to create multiple specialized pixel types. By varying these parameters across different pixel groups, the system achieves both improved defocus detection and maintained image quality, as each parameter set is optimized for specific detection scenarios without permanently degrading overall sensor performance.
2Measurement precision
If aperture is stopped down during AF operation to clarify brightness pattern, then defocus detection accuracy is improved, but autofocus time increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple light shielding patterns that are already optimized for different focus states. Instead of needing to stop down the aperture during AF operation to clarify the brightness pattern, the system has already prepared specialized pixels with appropriate light shielding patterns that work effectively at the intended aperture setting. This eliminates the time-consuming aperture adjustment step while maintaining detection accuracy.
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 quick and accurate focus detection in largely-defocused states while maintaining image quality performance by utilizing focus detecting pixels with different light shielding ratios and arrangements that improve defocus amount calculation.
Implementation Method 1
a photodiode, and a color filter, are arranged in correspondence with each other in a one-to-one manner
Data Source
AI summary
An image sensor comprising a plurality of imaging pixels, a plurality of focus detecting pixels in which opening positions of light receiving sections are shifted from those of the imaging pixels, and a plurality of color filters arranged corresponding to the imaging pixels and the focus detecting pixels, wherein first focus detecting pixels in which opening positions are shifted in a first direction are arranged at positions corresponding to first color filters of the imaging pixels, and second focus detecting pixels in which opening positions are shifted in the first direction and which have opening ratios different from those of the first focus detecting pixels are arranged at positions corresponding to the first color filters.