Auto Focus Adjusting Apparatus for Moving Subject Compensation
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Solution Overview
Problem
Existing auto focus methods, particularly contrast AF, face challenges in quickly and accurately focusing on moving subjects during continuous photography due to the time required to detect peak contrast values.
Innovation Solution
An auto focus adjusting method and apparatus that includes an image pickup lens with a variable focus lens, a focus lens driver, an image pickup device, an AF calculator, a peak detector, and a speed calculator, which detects the peak position of focus detection evaluation values and calculates the moving speed of the subject before exposure, allowing for moving body compensation driving to adjust the focal position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contrast AF method is used to detect peak contrast value, then focus accuracy is improved, but focusing speed deteriorates
Solution Approach 1:
The patent performs peak position detection in the image pickup interval before the light exposure preparation interval. By detecting the peak position in advance (preliminarily) during the image pickup interval, the system prepares the focus information before the actual exposure begins, thus resolving the contradiction between accurate peak detection and fast focusing response.
Solution Approach 2:
The patent implements moving body compensation driving that adjusts the focus lens position based on calculated subject moving speed. This dynamic adjustment allows the system to maintain accurate focus on moving subjects by continuously adapting the focal position to the subject's motion, thereby improving both focus accuracy and speed for moving objects.
2Measurement precision
If peak position detection is performed during light exposure preparation interval, then focusing accuracy is improved, but image capture timing is delayed
Solution Approach 1:
The patent performs peak position detection during the image pickup interval, which occurs before the light exposure preparation interval. This preliminary detection ensures that focus information is obtained in advance, avoiding any delay to the image capture timing while maintaining accurate focus detection.
Solution Approach 2:
The patent enables continuous operation by performing peak detection, moving speed calculation, and moving body compensation driving in a continuous sequence during the intervals between image captures. This continuous useful action ensures that the system is always prepared for the next capture without timing delays, maintaining both accuracy and timing efficiency.
3Measurement precision
If moving body compensation driving is performed, then focus accuracy on moving subjects is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the system detects peak positions, calculates subject moving speed based on peak position changes, and uses this feedback to perform moving body compensation driving. This feedback loop continuously adjusts the focus lens position to track moving subjects, improving focus accuracy while using a systematic approach to manage complexity.
Solution Approach 2:
The system uses its own detected peak position information and calculated moving speed to automatically perform the moving body compensation driving without external intervention. The autofocus system serves itself by using its detection capabilities to drive the compensation mechanism, reducing the need for additional complex external control systems.
Data Source
AI summary
An auto focus (AF) adjusting method, an AF adjusting apparatus, and a digital photographing apparatus including the same, the AF adjusting apparatus including: an AF calculator for calculating focus detection evaluation values; a peak detector for detecting a peak position of the focus detection evaluation values; and a speed calculator for calculating a moving speed of a subject by using the peak position. When continuous photographing of still images is performed, the peak detector detects the peak position in an image pickup interval before a light exposure preparation interval for image capturing, and the focus lens driver performs moving body compensation driving for compensating for a focal position by using a moving speed calculated in the light exposure preparation interval before capturing starts.