Autofocus Prediction and Dynamic Scan Control
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Solution Overview
Problem
Conventional autofocus techniques face difficulties in maintaining focus on moving subjects, especially under low contrast or low-light conditions, and may result in false focusing due to inappropriate scan area distribution.
Innovation Solution
A focusing control device that includes a scan control unit, a focus determination unit, and a prediction unit to predict the in-focus position based on previous exposure data, adjusting scan areas dynamically to ensure accurate focusing during continuous shooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If prediction of in-focus position is performed based on previous exposure data, then focusing speed is improved, but reliability deteriorates under low contrast or low-light conditions
Solution Approach 1:
The system performs preliminary scan operations to acquire focus evaluation values before relying on prediction, ensuring that even under low contrast or low-light conditions, accurate focus data is obtained in advance. This preliminary action provides a fallback mechanism when prediction reliability is questionable.
Solution Approach 2:
The system continuously monitors focus evaluation values and compares predicted positions with actual scan results, using this feedback to adjust and improve prediction accuracy over time. This feedback mechanism allows the system to adapt to varying lighting and contrast conditions dynamically.
2Measurement precision
If scan area is distributed widely to cover moving subject, then focusing accuracy on moving subject is improved, but false focusing on still subject increases
Solution Approach 1:
The scan area distribution is made dynamic rather than static. The system adjusts the scan area width based on detected subject movement, expanding it when movement is detected and narrowing it when the subject is still. This dynamic adjustment prevents false focusing on still subjects while maintaining accuracy on moving subjects.
Solution Approach 2:
The system changes the parameter of scan area width based on subject movement detection. By varying this parameter dynamically, the system optimizes the balance between capturing moving subjects accurately and avoiding false focus on still subjects.
3Reliability
If scan operation is performed continuously, then focusing reliability is improved, but productivity deteriorates due to increased processing time
Solution Approach 1:
Instead of continuous scan operations, the system implements periodic scanning combined with prediction. Scan operations are performed at specific intervals to acquire focus evaluation values, while prediction fills in between these intervals. This periodic approach maintains reliability while improving continuous shooting speed.
Solution Approach 2:
The system performs scan operations in advance to acquire focus data before it is needed for the next shot. This preliminary action allows the system to prepare focus information ahead of time, reducing processing delays during continuous shooting while maintaining focusing reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively maintains focus on moving subjects and prevents significant defocusing, even under low contrast or low-light conditions, by dynamically adjusting scan areas based on previous exposure data.
Implementation Method 1
image signals obtained by an imaging element performing photoelectric conversion of subject images focused by a photographic optical system
Data Source
AI summary
A focusing control device that can keep a moving subject in focus and can prevent significant defocusing of a low contrast subject or under a low-light intensity condition during continuous shooting. The focusing control device determines whether an in-focus position of a focusing lens can be obtained, predicts an in-focus position for the current exposure operation based on an in-focus position for the previous exposure operation when continuous main exposure operation is performed for shooting, and determines whether prediction of an in-focus position is possible. When prediction of an in-focus position for the current exposure operation is determined to be not possible, the focusing control device performs a scan operation to obtain an in-focus position based on an in-focus position of the previous exposure operation where obtaining of an in-focus position of the focusing lens was determined to be possible.