Interchangeable Lens Autofocus Control via Direction Feedback
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Solution Overview
Problem
Existing camera systems face challenges in accurately controlling autofocus during moving image recording due to uncertainties in the drive condition of the focus lens, leading to potential false control.
Innovation Solution
A camera system comprising an interchangeable lens and camera body that includes a focus lens, driver, lens-side and camera-side units for obtaining and transmitting control signals and information about the focus lens's direction and operational availability, enabling accurate autofocus control through wobbling control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the camera body controls the focus lens without obtaining direction information from the lens, then the control system is simpler, but the autofocus control accuracy deteriorates due to uncertainty in drive conditions
Solution Approach 1:
The lens-side transmission unit transmits direction information (first direction or second direction) about the focus lens movement to the camera body. The camera-side obtaining unit receives this feedback, allowing the camera controller to accurately know the drive condition of the focus lens and adjust subsequent control signals accordingly, preventing false autofocus control.
Solution Approach 2:
The lens-side transmission unit acts as an intermediary that conveys direction information from the lens drive system to the camera body. This intermediary component enables accurate communication of drive conditions without significantly increasing overall system complexity.
2Speed
If the focus lens is driven without information about operational availability, then the control process is faster, but the reliability of autofocus control deteriorates due to potential false control
Solution Approach 1:
The lens-side transmission unit transmits availability information indicating whether the focus lens can be driven in the instructed direction before the actual drive operation. This preliminary information allows the camera controller to verify drive feasibility and adjust control signals in advance, preventing false control while maintaining fast response.
Solution Approach 2:
The camera-side obtaining unit obtains availability information from the lens, creating a feedback loop that verifies drive conditions before execution. This feedback mechanism ensures reliable autofocus control by confirming the focus lens can actually respond to control signals.
3Device complexity
If the camera body does not obtain direction information from the lens, then the communication protocol is simpler, but the measurement of focus drive condition becomes inaccurate
Solution Approach 1:
The lens-side transmission unit provides feedback about the direction (first or second direction) in which the focus lens will move or has moved. This feedback information is transmitted through the communication interface between lens and camera body, enabling accurate tracking of focus drive conditions without significantly complicating the communication protocol.
Solution Approach 2:
The interchangeable lens autonomously determines and transmits its own drive direction information to the camera body. This self-service approach allows the lens to provide accurate drive condition information without requiring complex external monitoring systems.
Data Source
AI summary
An interchangeable lens mountable to a camera body, includes a focus lens operable to adjust a focus state of a subject, a driver operable to drive the focus lens by repeatedly performing slight advancing and retreating of the focus lens along an optical axis, a lens-side obtaining unit operable to obtain a control signal for driving the driver from the camera body, and a lens-side transmission unit operable to transmit, to the camera body, information about a direction of slight advancing and retreating operations of the focus lens.