Off-Centered Aperture Pixel Cells for Phase Difference Detection
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Solution Overview
Problem
Recent imaging elements face challenges in precisely detecting phase differences due to varying spot light sizes on pixel cells, leading to reduced precision in phase difference AF and unnatural coloration in captured images, especially when using multiple types of focus detecting pixel cells that detect different colors.
Innovation Solution
The imaging element employs pairs of pixel cells with off-centered light shielding film apertures, where the distance from the optical axis to the aperture center varies based on the wavelength detected, ensuring that the pixel cell detecting the longest wavelength has the largest spot size, thereby maintaining precision in phase difference detection across different pupil areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pixel cells detecting different colors are used as focus detecting pixel cells, then phase difference AF can be performed, but the spot light size varies depending on wavelength causing variation in phase difference detection precision
Solution Approach 1:
The patent applies local quality by configuring each pixel cell type (R, G, B) with specific aperture positions tailored to its wavelength characteristics. The light shielding film apertures are positioned at different locations for different color pixel cells, with longer wavelength pixels (R) having apertures positioned to accommodate larger spot light sizes, while shorter wavelength pixels (B) have apertures positioned for smaller spot light sizes. This localized optimization ensures each pixel cell type maintains consistent phase difference detection precision despite varying spot light dimensions.
Solution Approach 2:
The patent changes the positional parameter of the light shielding film apertures based on the wavelength detected by each pixel cell. Specifically, the distance from the optical axis to the aperture center is adjusted according to the spot light size characteristics of each color channel. This parameter adjustment compensates for the wavelength-dependent spot light size variations, maintaining uniform phase difference detection accuracy across all color channels.
2Ease of manufacture
If pixel cells with fixed aperture positions are used, then manufacturing is simplified, but phase difference detection precision varies with wavelength
Solution Approach 1:
Rather than using a uniform aperture configuration for all pixel cells, the patent implements local quality by positioning apertures differently for each pixel cell type based on its wavelength characteristics. This approach increases manufacturing complexity slightly but ensures optimal phase difference detection precision for each color channel, resolving the trade-off between manufacturing simplicity and detection accuracy.
3Measurement precision
If the aperture position is optimized for one wavelength, then phase difference detection precision is improved for that wavelength, but precision deteriorates for other wavelengths
Solution Approach 1:
The patent changes the aperture position parameter for each pixel cell type to match its specific wavelength characteristics. By adjusting the distance from the optical axis to the aperture center according to spot light size, the system achieves optimal phase difference detection precision for each wavelength band (R, G, B) simultaneously, rather than optimizing for only one wavelength at the expense of others.
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 allows for precise detection of phase differences between luminous fluxes passing through different pupil areas, enhancing the precision of phase difference AF and preventing unnatural coloration, thus improving imaging quality.
Implementation Method 1
micro lenses provided at light entrance sides of the photoelectric converting units to condense lights onto the photoelectric converting units
Implementation Method 2
pixel cells including photoelectric converting units
Data Source
AI summary
A solid-state imaging element includes pixel cells in which apertures of light shielding films are off-centered in opposite directions. The pixel cells includes a pixel cell which detects a R light component, a pixel cell which detects a G light component, and a pixel cell which detects a B light component. In the pixel cells, a relationship among an off-centered amount Or of the aperture in the pixel cell which detects the R light component, an off-centered amount Og of the aperture in the pixel cell which detects the G light component, and an off-centered amount Ob of the aperture in the pixel cell which detects the B light component is Or>Og>Ob.