Adaptive Phase Difference Focusing Filter Control
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Solution Overview
Problem
Existing phase difference focusing methods in imaging devices, such as digital cameras, face challenges in accurately detecting phase differences during high-resolution imaging, especially under varying subject conditions like brightness, spatial frequency, and contrast, leading to unstable focus and discomfort in video capturing.
Innovation Solution
A focusing control device with first and second signal detection units, filter processing units, correlation calculation units, and lens position control units that select appropriate filter processing based on subject conditions to enhance phase difference detection accuracy, using differential and integral filter processing to adapt to changing imaging conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If differential filter processing is performed on each signal group to increase detection resolution of phase difference, then detection resolution is improved, but phase difference detection fails or becomes incorrect under certain subject conditions
Solution Approach 1:
The patent changes the processing parameter by switching between differential filter processing and integral filter processing based on subject conditions. When differential processing fails under certain conditions (low brightness, specific spatial frequencies), the system switches to integral filter processing, which applies cumulative summation instead of differential calculation, thereby maintaining reliable phase difference detection across varying subject conditions while preserving high detection resolution.
2Speed
If phase difference AF method is used for moving image capturing, then high-speed processing is achieved, but focus stability deteriorates when phase difference detection fails
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors subject conditions (brightness, spatial frequency, contrast) and adjusts the filter processing method accordingly. When detection reliability drops under certain conditions, the feedback loop triggers a switch to alternative processing, ensuring focus stability is maintained without sacrificing the high-speed processing capability of phase difference AF.
3Ease of operation
If still image capturing is performed, then manual focus adjustment can compensate for detection issues, but moving image capturing cannot adapt in real-time
Solution Approach 1:
The patent enables the system to serve itself by automatically detecting subject conditions and selecting the appropriate filter processing method without user intervention. This self-service capability allows real-time adaptation during moving image capturing, eliminating the need for manual focus adjustment while maintaining ease of operation through automated decision-making based on captured image data.
Data Source
AI summary
A focusing control device includes a filter processing unit 11a which performs first filter processing selected from among a plurality of kinds of filter processing on each of a first signal group output from a plurality of phase difference detection pixels 52A and a second signal group output from a plurality of phase difference detection pixels 52B, a correlation calculation unit 11b which performs correlation calculation of the first signal group after the first filter processing and the second signal group after the first filter processing, and a lens position control unit 11c which controls a position of a focus lens based on the result of the correlation calculation. The filter processing unit 11a selects the first filter processing from among the plurality of kinds of filter processing based on subject condition information.