Focus Adjustment Device Using Contrast and Phase Difference Detection
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Solution Overview
Problem
Existing focus adjustment systems face challenges in precision and speed when either the phase difference detection system or contrast detection system cannot be used, leading to inadequate focus adjustment and prolonged adjustment times.
Innovation Solution
A focus adjustment device incorporating both contrast and phase difference detection systems, with a control unit that dynamically switches between them to ensure accurate focus detection and adjustment, using image signals to evaluate contrast and phase difference for optimal focus positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both phase difference detection system and contrast detection system are used sequentially, then focus detection accuracy is improved, but focus adjustment time is increased
Solution Approach 1:
The phase difference detection system performs preliminary focus detection to obtain initial focus information before the contrast detection system conducts detailed focus measurement. This preliminary action allows the contrast detection to start from a closer position to the optimal focus, reducing the time required for accurate focus detection while maintaining precision.
Solution Approach 2:
The patent implements continuous operation of both detection systems simultaneously rather than sequentially. The phase difference detection system continuously provides focus guidance while the contrast detection system continuously measures focus accuracy, allowing both systems to work in parallel and eliminate idle time between detection phases.
2Device complexity
If only one detection system is used, then device complexity is reduced, but focus detection reliability is insufficient when the single system cannot detect focus
Solution Approach 1:
The patent changes the operational parameters of the two detection systems based on scene conditions. When the phase difference detection system cannot obtain sufficient focus information (e.g., in low-contrast scenes), the system automatically switches to rely more heavily on the contrast detection system, and vice versa. This dynamic parameter adjustment maintains reliability without requiring both systems to operate at full complexity simultaneously.
Solution Approach 2:
The patent designs the detection system with multi-functionality where both the phase difference detection system and contrast detection system can serve as primary or backup detection methods depending on the imaging conditions. This universal design allows either system to take the lead role in different scenarios, ensuring reliable focus detection across diverse scenes without permanently increasing system complexity.
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
Enables precise and efficient focus adjustment by leveraging both detection systems, improving focus detection accuracy and reducing adjustment time, even in scenarios where one system is ineffective.
Implementation Method 1
a first detector (221) which uses a contrast detection system to detect a focused state; the first detector (221) uses an image signal which is output by the imaging unit as the basis to calculate an evaluation value which relates to contrast of the image formed by the optical system
Implementation Method 2
second detectors (222a, 222b) which use a phase difference detection system to detect a focused state; the second detectors (222a, 222b) use the phase difference to detect the focused state of the optical system
Data Source
AI summary
A focus adjustment device comprising: a first detector which detects a focused state by a contrast detection system; second detectors which detect a focused state by a phase difference detection system; and a control unit which controls the first detector and second detectors so as to detect the focused state by the second detectors when detecting the focused state by the first detector.