Variable Focus Detection Area Lens Apparatus
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Solution Overview
Problem
Existing auto-focusing technologies in cameras face challenges in maintaining high precision and speed due to changes in magnification and aspect ratios, which disrupt the relationship between the image pickup side and focus detection side, leading to improper focusing operations.
Innovation Solution
A lens apparatus with a branching optical system, a focus detector, and a driving unit controlled by an operational circuit, allowing for variable focus detection area size, driving amount, and detection precision to maintain optimal focusing performance across different shooting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the relationship between image pickup side and focus detection side is kept fixed, then focusing precision is maintained, but the system cannot adapt to changes in magnification and aspect ratio
Solution Approach 1:
The patent applies dynamics by making the focus detection area size variable rather than fixed. The operational circuit dynamically adjusts the focus detection area size based on detection signals, allowing the system to adapt to different magnification and aspect ratio conditions while maintaining focusing precision through real-time parameter changes.
Solution Approach 2:
The patent implements parameter changes by varying the focus detection area size as a controllable parameter. The operational circuit changes this parameter in response to detection signals, enabling the system to accommodate different shooting conditions (such as converter lens mounting or image pickup element changes) while preserving accurate focusing control.
2Adaptability or versatility
If the focus detection area size is made variable, then adaptability to different shooting conditions is improved, but the device complexity increases
Solution Approach 1:
The operational circuit is designed to perform multiple functions: it detects focus state, determines appropriate focus detection area size based on shooting conditions, and controls the focus moving unit. This multi-functionality reduces the need for separate control mechanisms for each function, thereby limiting the increase in device complexity while achieving high adaptability.
Solution Approach 2:
The operational circuit automatically adjusts the focus detection area size based on detection signals without requiring external intervention or complex external control systems. The system self-regulates its parameters to adapt to different shooting conditions, minimizing the need for additional complex control infrastructure.
3Measurement precision
If focusing precision is prioritized, then measurement accuracy is improved, but focusing speed decreases
Solution Approach 1:
The system dynamically adjusts the focus detection area size based on shooting conditions. For moving objects, a larger detection area is used to enable faster focus acquisition with adequate precision. For stationary objects, a smaller detection area provides higher precision when speed is less critical. This dynamic parameter adjustment allows the system to optimize the precision-speed trade-off in real-time.
Solution Approach 2:
The operational circuit changes the focus detection area size parameter according to detection signals and shooting conditions. By varying this parameter, the system can achieve high precision when needed (smaller area for stationary objects) and maintain adequate precision with faster operation when speed is prioritized (larger area for moving objects), thus resolving the precision-speed contradiction.
Data Source
AI summary
A lens apparatus includes an imaging optical system including a focus lens unit, a branching optical unit disposed at the image side of the focus lens unit, a focus-state detecting unit including a focus detecting element having a focus detection area that receives light beams from the branching optical unit, and detecting a focus state by using the focus detecting element, an actuator that drives the focus lens unit in an optical axis direction thereof, a controller that controls the actuator, in accordance with an output from the focus-state detecting unit, and a movable image-side optical unit disposed at the image side of the branching optical unit. The controller changes the size of the focus detection area of the focus detecting element within a range in accordance with the position of the image-side optical unit.