Interchangeable Lens Zoom Mechanism for Focus Stability
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Solution Overview
Problem
Existing camera systems face challenges in maintaining focus during zoom reversal operations, as focus movement occurs due to changes in focal length, leading to an out-of-focus state.
Innovation Solution
An optical apparatus comprising a fixed member, a base moving member, a rotating member, and a detection unit that directly detects the relative position between the base moving member and the fixed member, allowing the base moving member to move in the optical axis direction by rotating the rotating member, thereby engaging with grooves and cam grooves to stabilize the lens positions during zoom changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical mechanism is used to change focal length during zooming, then the focal length can be adjusted, but focus movement occurs leading to out-of-focus state
Solution Approach 1:
The detection unit directly detects the relative position between the base moving member and fixed member before focus movement occurs, allowing the control unit to pre-adjust the focus lens position according to tracking data to compensate for upcoming focus movement during zoom reversal
Solution Approach 2:
The detection unit provides real-time feedback on the relative position between moving and fixed members, enabling the control unit to continuously adjust the focus lens position to maintain in-focus state throughout the zoom operation including reversal
2Reliability
If the position of the moving lens unit and focus lens are strictly controlled according to tracking data, then in-focus state can be maintained, but the system complexity increases
Solution Approach 1:
The detection unit acts as an intermediary that directly measures the relative position between the base moving member and fixed member, simplifying the control system by providing accurate position feedback without requiring complex multi-sensor arrangements
Solution Approach 2:
The detection unit serves multiple functions by directly detecting the relative position between moving and fixed members, which is used for both zoom position detection and focus control, reducing the need for separate detection systems
Data Source
AI summary
An interchangeable lens comprises a guide barrel, a rear base that moves in an optical axis direction, a cam ring rotatably held with respect to the guide barrel, and a zoom position detection scale and a zoom position detection sensor configured to directly detect a relative position between the rear base and the guide barrel. The rear base holds a fourth main bearing that engages with one of a rear rectilinear groove and a cam groove provided in the guide barrel and one of a rear cam groove and a rectilinear groove provided in the cam ring. The rear base moves in the optical axis direction by rotation of the cam ring.