Focus Detection Signal Generation for Phase Difference Autofocus Accuracy
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Solution Overview
Problem
In imaging-plane phase difference method, the difference between the detected in-focus position based on focus detection signals and the best in-focus position based on imaging signals leads to inaccurate focus detection due to differing spatial frequency bands.
Innovation Solution
Generating first and second focus detection signals from color signals received by different pupil regions in an imaging optical system, ensuring the centroids of these signals coincide in the pupil division direction to calculate defocus amounts accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If focus detection signals are generated from color signals received by different pupil regions, then focus detection speed is improved, but focus detection accuracy deteriorates due to spatial frequency band differences
Solution Approach 1:
The patent changes the spatial frequency band parameter of the focus detection signal to match the imaging signal's spatial frequency band. This is achieved by generating focus detection signals from color signals received by different pupil regions and adjusting their spatial frequency characteristics, thereby resolving the contradiction between fast focus detection and accurate focus positioning.
Solution Approach 2:
The patent applies different processing methods to different parts of the color signals based on their spatial frequency characteristics. By generating focus detection signals from specific pupil regions and adjusting their local spatial frequency properties, the system achieves both rapid detection and high accuracy without compromising overall image quality.
2Productivity
If phase difference detection method is used for high-speed focus control, then focus control speed is improved, but in-focus position accuracy deteriorates due to spatial frequency band mismatch
Solution Approach 1:
The patent modifies the spatial frequency band parameter of the focus detection signal to align with the imaging signal's spatial frequency band. This parameter adjustment enables the phase difference detection method to achieve both high-speed focus control and precise in-focus positioning by eliminating the spatial frequency mismatch that previously caused accuracy deterioration.
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 reduces the difference between detected and actual in-focus positions, enabling high-accuracy focus detection by aligning the spatial frequency bands of focus detection and imaging signals.
Implementation Method 1
an image pickup element which includes a first pixel group and a second pixel group configured to receive light beams passing through partial pupil regions different from each other
Data Source
AI summary
A control apparatus (121) includes a generation unit (121a) for generating first and second focus detection signals based on a plurality of types of color signals from first and second pixel groups that receive light beams passing through partial pupil regions different from each other, and a calculation unit (121b) for calculating a defocus amount by a phase difference detection method by using the first and second focus detection signals, and the generation unit combines the color signals with respect to the first pixel group so that centroids of the color signals in a pupil division direction coincide with each other to generate the first focus detection signal, and combines the color signals with respect to the second pixel group so that centroids of the color signals in the pupil division direction coincide with each other to generate the second focus detection signal.