Autofocus Control Apparatus Interpolation Lens Position
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Solution Overview
Problem
Existing autofocus (AF) control methods using the imaging-plane phase-difference method are susceptible to errors when frame addition is performed, as the calculated lens position at the accumulation center time does not accurately reflect the influence of lens driving, leading to inaccurate AF control.
Innovation Solution
A control apparatus with a processor and memory that performs interpolation processing to acquire the position of the optical system across the interval between accumulation center times for multiple frames, allowing for accurate prediction of the in-focus position and reducing prediction calculation errors during frame addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frame addition is performed to improve image quality, then image signal quality is improved, but lens position calculation accuracy deteriorates because the calculated lens position at accumulation center time does not reflect lens driving influence
Solution Approach 1:
The patent performs preliminary action by calculating the lens position at the accumulation center time using interpolation before the actual AF control is executed. This preliminary calculation ensures that the lens position reflects the lens driving influence that occurred during the accumulation period, allowing the AF control to be based on accurate and up-to-date position information.
Solution Approach 2:
The patent implements feedback by continuously monitoring the lens position during frame addition and using this information to adjust the AF control. The lens position calculated at the accumulation center time serves as feedback information that is used to correct and refine the AF control process, ensuring high accuracy even when frame addition is performed.
2Ease of operation
If interpolation is performed using lens positions before and after accumulation center time, then lens position can be calculated, but the calculated position does not reflect lens driving influence leading to prediction errors
Solution Approach 1:
The patent performs preliminary action by calculating the lens position at the accumulation center time using interpolation before the actual AF control is executed. This preliminary calculation ensures that the lens position reflects the lens driving influence that occurred during the accumulation period, allowing the AF control to be based on accurate and up-to-date position information.
Solution Approach 2:
The patent applies parameter changes by adjusting the interpolation method to account for lens driving during the accumulation period. Instead of using simple linear interpolation between fixed time points, the system modifies the interpolation parameters to reflect the dynamic lens position changes, thereby improving measurement precision while maintaining ease of operation.
Data Source
AI summary
A control apparatus includes an acquiring unit configured to acquire a position of an optical system based on an image signal, and a predicting unit configured to predict an in-focus position of the optical system based on the position acquired by the acquiring unit. The acquiring unit acquires the position of the optical system by performing interpolation processing in a range equal to or wider than an interval between first accumulation center time for a first frame in the image signal and second accumulation center time for a second frame in the image signal.