Autofocus Trigger Region of Focus Calculation
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Solution Overview
Problem
Current autofocus trigger systems in imaging devices often fail to reliably determine when an autofocus operation is needed, leading to unnecessary triggers or missed refocusing opportunities due to indirect metrics such as exposure changes or contrast variations.
Innovation Solution
The system determines the region of focus based on lens parameters like focusing distance, focal length, and aperture, and uses object tracking and distance monitoring to assess when the object distance falls outside this region, triggering an autofocus operation only when the object distance stabilizes outside the defined focus area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exposure change is used as a metric to trigger autofocus operation, then the system can detect lighting changes, but it causes unnecessary triggers when lighting changes occur without focus changes
Solution Approach 1:
The patent introduces an intermediary metric called 'region of focus' that mediates between the lens parameters and the autofocus trigger decision. Instead of directly using exposure change as a trigger metric, the system calculates the region of focus based on lens parameters (focusing distance, focal length, aperture) and compares the actual object distance to this region. This intermediary calculation filters out false triggers from lighting changes while maintaining sensitivity to actual focus changes.
2Device complexity
If indirect metrics like contrast or exposure are used to determine autofocus need, then the system can operate with simpler sensing, but it fails to reliably detect when refocusing is actually needed
Solution Approach 1:
The patent replaces indirect optical sensing methods (contrast detection, exposure monitoring) with a direct geometric calculation approach. Instead of using optical sensors to detect focus quality, the system uses lens parameters (focusing distance, focal length, aperture) to mathematically calculate the region of focus and determine whether the object distance falls outside this region. This substitution of mechanical/optical sensing with geometric calculation improves reliability while maintaining relatively simple system complexity.
3Reliability
If the system triggers autofocus on any scene change detection, then it ensures focus is updated frequently, but it triggers too often including false detections from non-focus-related changes
Solution Approach 1:
The patent applies local quality by making the autofocus trigger decision specific to the object of interest rather than the entire scene. The system calculates a region of focus specific to the tracked object based on lens parameters and object distance, and only triggers autofocus when this specific object's distance falls outside its calculated region. This localized approach prevents false triggers from unrelated scene changes while ensuring timely focus updates for the actual subject.
Data Source
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AI summary
Method and systems for autofocus triggering focusing are disclosed herein. In one example, a system may include a lens, a memory component configured to store lens parameters of the lens and regions of focus corresponding to the lens parameters, and a processor coupled to the memory and the lens. The processor may be configured to focus the lens on a target object at a first instance of time, receive information indicative of distances from an imaging device to the target object over a period of time, obtain lens parameters of the lens, and determine a region of focus, and trigger the lens to re-focus on the target object if the distance to the target object indicates the target object is outside of the region of focus and the distance to the target object is unchanged for a designated time period.