Autofocus Control Correcting Swirl Error in Thinned Phase Pixels
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing imaging apparatuses face challenges in maintaining focus detection precision when subject inclination causes swirl error, especially when focus detection pixels are thinned for increased readout speed, as previous solutions do not adequately address the reduced precision and swirl error correction.
Innovation Solution
An imaging apparatus with a two-dimensional array of focus detection and imaging pixels, including a readout section for thinning focus detection pixel signals, a focus detection section using phase difference detection, a swirl error determination section, and an AF control section that adjusts autofocus operations based on swirl error determination, allowing for accurate autofocus even with thinned readout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If focus detection pixels are thinned to increase readout speed, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
A swirl error determination section is introduced as an intermediary component that calculates correction values for swirl error based on thinned pixel signals. This mediator allows the system to maintain measurement precision by compensating for the precision loss caused by pixel thinning, enabling accurate phase difference AF even with reduced pixel sampling
Solution Approach 2:
The system dynamically changes processing parameters by applying swirl error correction values to the thinned pixel signals. By adjusting the correction parameter based on detected swirl error, the system maintains measurement precision despite the reduced number of pixels used for phase difference detection
2Manufacturing precision
If focus detection pixels are thinned to improve live view image quality, then image quality is improved, but phase difference AF precision deteriorates
Solution Approach 1:
The swirl error determination section serves as a mediator that enables the system to use thinned pixel readings for both improved live view quality and accurate focus detection. By calculating and applying correction values, it bridges the gap between using fewer pixels for display and maintaining precision for measurement
3Adaptability or versatility
If subject inclination is present, then swirl error occurs, but focus detection precision deteriorates
Solution Approach 1:
The system converts the harmful effect of subject inclination (which causes swirl error and precision loss) into a beneficial correction process. By detecting the swirl error pattern caused by inclination and applying appropriate correction values, the system not only compensates for the error but also enables accurate focus detection for inclined subjects that would otherwise be impossible
Solution Approach 2:
A feedback mechanism is implemented where the swirl error determination section continuously monitors for inclination-induced errors and feeds back correction values to the phase difference AF calculation. This closed-loop feedback ensures that focus detection precision is maintained despite subject inclination by dynamically adjusting for the swirl error
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
The solution enables accurate autofocus operations by determining and correcting swirl error, maintaining focus detection precision even when focus detection pixels are reduced, thereby improving image quality during live view display and image capture.
Implementation Method 1
a plurality of pixels provided with photoelectric conversion sections converting an optical image formed by an imaging optical system into electrical signals
Data Source
AI summary
An imaging apparatus, comprising a focus detection section that detects an out of focus amount and an out of focus direction by carrying out a focus detection operation using phase difference detection based on a pixel signal of focus detection pixels that has been thinned and read out, a swirl error determination section that determines swirl error arising in accordance with inclination of an optical image with respect to a direction that is orthogonal to a phase difference detection direction, based on the pixel signal of the focus detection pixels that has been thinned and read out, and an AF control section that determines whether or not to carry out AF operation adopting output of the focus detection section, based on output of the swirl error determination section.