Digital Camera Autofocus Buffer Management for Continuous Shooting
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Solution Overview
Problem
Conventional digital cameras experience a slowdown in continuous shooting speed due to the autofocus process, leading to a high number of out-of-focus shots during continuous shooting, especially when capturing moving objects.
Innovation Solution
The digital camera system performs autofocus operations in conjunction with continuous shooting by using a buffer memory to suspend and resume photographing and focus-state detection processes, switching between AF modes to determine if the target object is stationary or moving, allowing for continuous shooting with minimal loss of speed and focus accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AF process is performed each time a picture is taken during continuous shooting, then the camera remains in focus, but the continuous shooting speed is slowed down
Solution Approach 1:
The camera performs autofocus in advance before continuous shooting begins, and then maintains focus by periodically rechecking focus state during shooting without performing full focusing lens group driving. This preliminary action allows the system to prepare focus in advance while avoiding repeated time-consuming focus adjustments during shooting.
Solution Approach 2:
The system dynamically adjusts the autofocus behavior based on the buffer memory status. When the buffer is not full, it performs lightweight focus state detection without driving the lens. When the buffer becomes full, it performs complete autofocus processing. This dynamic adaptation optimizes both speed and focus reliability.
2Productivity
If the camera is in AF lock state during continuous shooting, then the shooting speed is maintained, but the camera becomes out of focus when shooting moving objects
Solution Approach 1:
The system continuously monitors focus state during continuous shooting by detecting focus information from captured images. This feedback mechanism allows the camera to maintain AF lock for speed while periodically verifying focus accuracy, and to trigger autofocus when focus degradation is detected.
Solution Approach 2:
Instead of continuous autofocus processing, the system performs periodic focus state detection at intervals during continuous shooting. This periodic action maintains focus reliability for moving objects while minimizing interference with the continuous shooting speed.
3Reliability
If the imaging system suspends photographing operation when the buffer memory is full, then focus detection can be performed, but the shooting process is interrupted
Solution Approach 1:
When the buffer memory is full, the system performs only the necessary focus detection and adjustment actions without suspending the entire photographing operation. It performs partial autofocus processing on the buffered images and then resumes shooting, minimizing interruption time while ensuring focus reliability.
Data Source
AI summary
A digital camera includes an imaging system which performs a photographing operation and records captured image files in a buffer memory; an AF system which performs a focus-state detection process, in which the AF system detects a focus state, and a focusing lens group driving process, in which the AF system moves a focusing lens group to an in-focus position; and first and second switches which actuate the AF system and the imaging system, respectively. While the first and second switches are held ON, the digital camera performs a continuous shooting process in which the imaging system repeatedly performs the photographing operation and the AF system repeatedly performs the focus-state detection process. Upon the buffer memory becoming full during the continuous shooting process, the imaging system suspends the photographing operation and the AF system performs the focus-state detection process and the focusing lens group driving process.