Passive Auto-Focus Device Adaptive Range Search
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Solution Overview
Problem
Passive auto-focus techniques face challenges with slow focusing speed and noise influence due to fixed focus-searching ranges, which can lead to erroneous focusing by either including or missing scenes of different depths of field.
Innovation Solution
A passive auto-focus device and method that adaptively determines a focus-searching range and step by comparing the current scene with a preceding scene, using a focus-searching-range decision circuit and a focal-distance-variation decision circuit to set appropriate ranges and steps for efficient focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed focus-searching range is used, then the focusing process is simple, but the focusing speed is slow and accuracy is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed focus-searching range to a variable range that adapts based on scene depth characteristics. The system dynamically adjusts the search range according to the detected depth information, allowing faster convergence on in-focus regions while maintaining simplicity through automated adaptation rather than manual intervention.
Solution Approach 2:
The patent changes the parameter of focus-searching range from a constant value to a variable parameter that depends on scene depth. By modifying the search range parameter based on depth detection results, the system achieves faster and more accurate focusing without requiring complex manual adjustment mechanisms.
2Adaptability or versatility
If a broad focus-searching range is used, then more scenes are covered, but erroneous focusing occurs due to including scenes of different depths
Solution Approach 1:
The patent applies local quality by focusing the search on specific depth regions rather than uniformly searching the entire range. The system identifies the depth region containing the in-focus scene and concentrates the search within that localized depth range, improving both scene coverage for the target object and focusing accuracy by excluding out-of-focus regions.
Solution Approach 2:
The patent uses feedback from depth detection to adjust the focus-searching range. The system continuously monitors the depth characteristics of captured images and uses this feedback to refine the search range, ensuring that only relevant scenes within the appropriate depth range are considered, thereby preventing erroneous focusing while maintaining comprehensive coverage.
3Measurement precision
If a narrow focus-searching range is used, then focusing precision is improved, but the target scene may be missed
Solution Approach 1:
The patent applies preliminary action by performing depth detection and scene analysis before initiating the focus search. The system preliminarily identifies the expected depth range of the target scene based on captured image data, then uses this information to set an appropriate search range that is narrow enough for precision but broad enough to guarantee target inclusion.
Solution Approach 2:
The patent uses dynamics to adjust the search range based on real-time depth detection. Rather than using a fixed narrow range that might miss the target, the system dynamically expands or contracts the search range according to the detected depth characteristics, ensuring both precision and reliability in target scene detection.
Data Source
AI summary
A passive auto-focus device and method are disclosed herein. An embodiment of the passive auto-focus device comprises: a focus-searching-range decision circuit operable to compare a range of a variation area of a current scene with a predetermined range and determine a focus-searching range, in which the variation area is defined according to the comparison between the current scene and a preceding scene; a focal-distance-variation decision circuit operable to compare the definition pertaining to the focus-searching range with a first predetermined definition and generate a current step setting value; an image record generating circuit operable to generate first step image records in connection with the focus-searching range while the current step setting value indicates a first step and to generate second step image records in connection with the focus-searching range while the current step setting value indicates a second step, in which the first step is shorter than the second step.