Lens Apparatus with Composite Focus Control for Continuous AF
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Solution Overview
Problem
Existing camera systems face challenges in accurately performing automatic focus control when multiple focus units are present, leading to errors and complications in communication and control, especially during continuous AF and moving image capturing.
Innovation Solution
A lens apparatus and camera system that integrates multiple focus units into a composite focus unit, allowing for a single driving command to be generated and transmitted, compensating for potential lags in focus unit movements, and maintaining accurate focus control through the use of a composite focus position and sensitivity calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple focus units are controlled independently with separate driving commands, then each focus unit can be precisely controlled, but the camera system requires program updates and complex control logic that increases error probability
Solution Approach 1:
The patent combines multiple focus units into a single composite focus unit concept. The lens apparatus integrates the positions and drive amounts of multiple focus units (first focus unit and second focus unit) into unified control parameters that the camera can handle as a single entity. This merging approach maintains precise control over each focus unit while presenting a simplified interface to the camera system, avoiding the need for program updates and reducing control complexity.
Solution Approach 2:
The lens apparatus acts as an intermediary between the camera's single driving command and the multiple focus units. It receives one driving command from the camera, internally processes it to determine appropriate drive amounts for each focus unit based on their respective positions and characteristics, and then controls each focus unit accordingly. This intermediary role resolves the contradiction by translating between the camera's simplified control interface and the complex multi-unit actuation requirements.
2Device complexity
If only one driving command is generated for a lens apparatus with multiple focus units, then communication remains simple, but the correspondence relation between focus unit position and defocus amount collapses when focus units move at different speeds
Solution Approach 1:
The patent implements dynamic control by continuously monitoring the positions of multiple focus units and adjusting their drive amounts in real-time based on current state. The lens apparatus calculates appropriate drive amounts for each focus unit considering their respective positions, movement characteristics, and the single driving command received from the camera. This dynamic adjustment ensures that even when focus units move at different speeds, the correspondence relation between focus unit position and defocus amount is maintained, preserving control reliability while keeping communication simple.
3Ease of operation
If the camera transmits multiple driving commands for multiple focus units, then each focus unit receives appropriate control signals, but program updates and complicated control increase error likelihood
Solution Approach 1:
The patent merges the control of multiple focus units into a single driving command interface. The lens apparatus receives one driving command from the camera that encompasses control for all focus units, internally processes this unified command to determine individual drive amounts for each focus unit, and executes the control. This approach maintains full focus control capability while avoiding the need for the camera program to handle multiple separate commands, thereby reducing complexity and error likelihood.
Data Source
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AI summary
The lens apparatus according to the present invention includes an optical system including a plurality of lens units configured to move in adjusting an in-focus state of a subject image, a detection unit configured to detect respective positions of the plurality of lens units, an acquisition unit configured to acquire position information regarding a single position representing the respective positions of the plurality of lens units corresponding to a current subject distance, based on the respective positions of the plurality of lens units and relational information indicating a relation between a subject distance and the respective positions of the plurality of lens units, and a control unit configured to control the respective positions of the plurality of lens units based on the position information acquired by the acquisition unit.