Phase-Detection Imaging Layout for Astigmatism-Aware Autofocus
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Solution Overview
Problem
Existing imaging devices face challenges in accurately adjusting focus positions due to parallax changes caused by lens astigmatism, particularly in structures where a single microlens is applied to multiple pixels, leading to non-uniform focus adjustment and difficulties in performing autofocus operations.
Innovation Solution
The imaging device measures parallax considering central symmetry around the optical axis, using a pixel array with phase-difference detection pixels to calculate radial and tangential parallax, and adjusts the focus position based on these calculations to improve autofocus accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single microlens is applied to multiple pixels to improve device structure, then device complexity is reduced, but manufacturing precision and focus uniformity deteriorate due to parallax changes caused by lens astigmatism
Solution Approach 1:
The patent segments the pixel array into multiple regions, each with its own reference pixel for parallax calculation. By dividing the image field into different zones and calculating parallax separately for each zone, the system compensates for astigmatism-induced focus variations across different field positions, thereby maintaining focus precision without increasing overall structural complexity
Solution Approach 2:
The patent dynamically adjusts parallax calculation parameters based on the position of phase-difference detection pixels relative to reference pixels. By changing the reference pixel selection and parallax calculation method according to spatial position, the system compensates for astigmatism effects and maintains uniform focus adjustment across the entire image field
2Device complexity
If traditional autofocus methods are used without considering central symmetry, then calculation simplicity is maintained, but measurement precision of parallax deteriorates due to astigmatism effects
Solution Approach 1:
The patent introduces asymmetric parallax calculation methods that account for the directional nature of astigmatism. By calculating parallax differently in radial and tangential directions relative to the optical axis, and by selecting reference pixels based on asymmetric positioning strategies, the system achieves accurate parallax measurement that compensates for astigmatism while maintaining reasonable calculation complexity
3Productivity
If focus adjustment is performed without considering radial and tangential parallax separately, then processing speed is maintained, but focus uniformity across the image field deteriorates
Solution Approach 1:
The patent implements dynamic parallax calculation that adapts to the position of phase-difference detection pixels in real-time. By dynamically selecting reference pixels and adjusting calculation parameters based on spatial position, the system maintains focus uniformity across the image field while avoiding excessive processing overhead through efficient conditional logic
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 approach enables accurate and uniform focus adjustment across the image field, enhancing autofocus performance by accounting for astigmatism effects and maintaining central symmetry, thereby improving image clarity and focus precision.
Implementation Method 1
a plurality of phase-difference detection pixels configured to detect phase difference information in light rays from the target object
Implementation Method 2
calculate a parallax for the plurality of phase images in at least one of a first direction proceeding from a center point of an optical axis or a second direction perpendicular to the first direction
Data Source
AI summary
An imaging device is provided to include a pixel array including phase-difference detection pixels; a position determiner configured to determine a position of each unit pixel; a weight setting unit configured to set different weights for each position of each phase-difference detection pixel based on an output signal of the position determiner; a signal blending unit configured to generate phase images by adding the weight set by the weight setting unit to each phase-difference detection pixel; a parallax calculator configured to calculate a parallax in at least one direction from among a first direction from a center point of an optical axis in the phase images and a second direction from the center point of the optical axis in the phase images; and a focus position determiner configured to generate a driving signal for adjusting a position of a lens based on the parallax calculated by the parallax calculator.