Focusing Control Device Magnification Adaptation
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Solution Overview
Problem
In autofocus systems, changes in image magnification cause the subject image to deviate within the distance measurement area, leading to inaccurate focusing and blurred images, as existing technologies fail to accurately determine the focusing position when the image of the subject moves relative to the focus lens.
Innovation Solution
A focusing control device and method that adjusts the processing based on image magnification changes, using either multi-point distance measurement or addition area distance measurement to stabilize contrast value detection, switching between these methods based on the amount of image position change, ensuring accurate focusing by moving the focus lens to the specified position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contrast value peak search is performed within a fixed distance measurement area, then focusing position can be determined, but the subject image may deviate from the measurement area due to image magnification changes, leading to inaccurate focusing
Solution Approach 1:
The distance measurement area is dynamically adjusted based on the amount of image magnification change. When magnification change exceeds a threshold, the measurement area is expanded to ensure the subject image remains within the measurement area throughout the focusing process, preventing measurement errors while maintaining focusing accuracy.
Solution Approach 2:
The size of the distance measurement area is changed as a parameter in response to image magnification changes. By adjusting the measurement area size according to the magnification change amount, the system adapts to different focusing conditions and ensures accurate subject image measurement regardless of magnification variations.
2Reliability
If the distance measurement area is expanded to accommodate image magnification changes, then the subject image remains within the measurement area, but the contrast value detection becomes less precise due to including more background areas
Solution Approach 1:
The distance measurement area is divided into multiple sub-areas, and contrast values are calculated for each sub-area separately. This segmentation allows the system to maintain a larger overall measurement area to accommodate magnification changes while still achieving precise contrast measurement by focusing on specific sub-regions where the subject image is located.
Solution Approach 2:
Different regions within the distance measurement area are treated with different quality requirements. The system identifies and prioritizes the local region containing the subject image for high-precision contrast measurement, while allowing other regions to serve the broader function of accommodating magnification changes without compromising overall measurement accuracy.
3Reliability
If multiple distance measurement areas are used to handle image deviation, then the subject image can be tracked, but the processing complexity increases due to multiple contrast value calculations and peak searches
Solution Approach 1:
Multiple distance measurement areas are merged into a single integrated processing framework. The system performs contrast value calculations and peak searches across multiple areas but combines the results through a unified selection process, reducing the overall processing complexity compared to independent processing of each measurement area while still maintaining reliable subject image tracking.
Solution Approach 2:
The system performs contrast value calculations for multiple distance measurement areas, but only processes the results from areas that actually contain the subject image. This partial processing approach reduces unnecessary calculations and processing complexity while ensuring the subject image is properly tracked and measured.
Data Source
AI summary
A focusing control device that moves a position of a focus lens included in an imaging lens along an optical axis direction. The device comprises a processor configured to execute a process. The process comprises receiving an input of a captured image obtained by imaging an optical image passed through the imaging lens including the focus lens; performing one processing of first processing that includes deriving a contrast value of an image within a distance measurement area which changes according to the movement of the position of the focus lens for each of a plurality of the distance measurement areas, specifying a peak of the contrast value based on the contrast value for each of the plurality of distance measurement areas, and specifying, as a focusing position, the position of the focus lens corresponding to the specified peak of the contrast value, or second processing that includes specifying the peak of the contrast value based on an added value obtained by adding the contrast values derived from the plurality of distance measurement areas and specifying, as the focusing position, the position of the focus lens corresponding to the specified peak of the contrast value; performing control such that the one processing is switched according to an amount of change of a position of an image of a subject corresponding to a change of an image magnification of the imaging lens, and moving the focus lens to the specified focusing position.