Built-In Optical Filter Focus Compensation for Close-Object Imaging
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Solution Overview
Problem
Image pickup apparatuses with built-in optical filters face challenges in maintaining focus on close objects when the optical filter is used, as the optical path length changes, leading to an out-of-focus state.
Innovation Solution
The image pickup apparatus includes an optical filter that can be moved between an inserted and retracted position, with a control unit that adjusts exposure settings and lens focus to maintain in-focus states by changing the optical path length and aperture settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the optical filter is inserted into the imaging range, then the exposure control is improved, but the imaging focus deteriorates
Solution Approach 1:
The patent implements dynamic focus adjustment by detecting whether an optical filter is inserted and automatically adjusting the focus lens position accordingly. The control unit changes the focus lens driving amount based on filter insertion state, transforming a static focus system into a dynamic one that adapts to different optical conditions. This resolves the contradiction by making the focus system responsive to filter presence, maintaining imaging precision while allowing exposure control benefits.
Solution Approach 2:
The patent employs feedback mechanisms where the control unit detects the optical filter insertion state and uses this information to adjust the focus lens driving amount. The system continuously monitors filter presence and compensates for optical path changes in real-time, creating a closed-loop control system that maintains focus accuracy despite filter-induced optical path variations.
2Ease of operation
If the optical filter is used, then the exposure control is improved, but the optical path length changes causing out-of-focus state
Solution Approach 1:
The patent changes the focus lens driving amount parameter based on the optical filter insertion state. When a filter is detected, the system adjusts the focus lens position by a predetermined amount to compensate for the optical path length change. This parameter adjustment approach allows the system to maintain proper focus while utilizing the exposure control benefits of the optical filter.
3Manufacturing precision
If the focus lens is moved to achieve focus, then the imaging focus is improved, but the optical path length change caused by filter insertion remains unaddressed
Solution Approach 1:
The patent applies preliminary action by detecting filter insertion before image capture and pre-adjusting the focus lens position accordingly. The control unit determines the appropriate focus lens driving amount based on filter presence and sets the focus before the actual imaging operation. This preliminary adjustment prevents focus issues rather than correcting them afterward, simplifying the overall optical path management.
Data Source
AI summary
An image pickup apparatus includes an image sensor, an optical filter movable between a first position at which the optical filter is inserted into an imaging range of the image sensor and a second position at which the optical filter is retracted from the imaging range, and a control unit configured to perform exposure control for the image sensor in a case where the optical filter is located at the first position and an in-focus state cannot be obtained by moving a focus lens.