Lens Barrel Focus Detection Using Variable Image Plane Transfer Coefficients
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Solution Overview
Problem
Existing lens barrels struggle to accurately detect the focus state of an optical system, particularly in varying positions of the focus adjustment lens.
Innovation Solution
A lens barrel equipped with an imaging optical system, a focus adjustment lens, a driver, a transceiver, and a controller that repeatedly transmits first and second image plane transfer coefficients to the camera body, allowing for precise focus detection and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a focus adjustment lens is driven at a predetermined driving speed to detect focus state, then the focus detection process can be simplified, but the accuracy of focus state detection deteriorates when the lens position varies
Solution Approach 1:
The patent applies dynamics by making the image plane transfer coefficient variable based on the focus adjustment lens position. Instead of using a fixed predetermined coefficient, the system dynamically selects or calculates the appropriate coefficient corresponding to the current lens position, thereby maintaining measurement precision across varying positions while keeping the detection process relatively simple
Solution Approach 2:
The patent changes the parameter of the image plane transfer coefficient from a fixed value to a variable value that depends on the focus adjustment lens position. By storing multiple coefficients corresponding to different lens positions and selecting the appropriate one, the system resolves the contradiction between simplified detection process and accurate focus state detection
2Device complexity
If a single image plane transfer coefficient is used for focus detection, then the system structure can be simplified, but the adaptability to different lens positions is reduced
Solution Approach 1:
The patent segments the image plane transfer coefficient into multiple discrete coefficients, each corresponding to a specific focus adjustment lens position. This segmentation allows the system to maintain a relatively simple structure while improving adaptability, as the controller can select from a finite set of pre-calculated coefficients rather than requiring a complex continuous calculation system
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing multiple image plane transfer coefficients corresponding to different focus adjustment lens positions before actual focus detection. This preparation allows the system to quickly adapt to different lens positions during operation without requiring complex real-time calculations, thus maintaining simple system structure while improving adaptability
Data Source
AI summary
A lens barrel of the invention includes: an imaging optical system including a focus adjustment lens; a driver that drives the focus adjustment lens in a direction of an optical axis; a transceiver that transmits and receives a signal to and from a camera body; and a controller that controls the transceiver to repeatedly transmit a first image plane transfer coefficient which is determined in correspondence with a position of the focus adjustment lens included in the imaging optical system and a second image plane transfer coefficient which does not depend on the position of the focus adjustment lens to the camera body at a predetermined interval, and, when the controller repeatedly transmits the second image plane transfer coefficient to the camera body, the controller varies the second image plane transfer coefficient over time.