Lens Barrel Zoom Tracking with Variable Speed Correction
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Solution Overview
Problem
Existing autofocus systems in imaging apparatuses are limited to zoom tracking operations where the zoom lens is electrically driven and fail to accurately control focus when the zoom lens is manually operated, as they do not account for the variable speed of manual zoom operations.
Innovation Solution
A lens barrel with a correction lens and a controller that uses position and rate detectors to determine a focus position based on relational information, adjusting the focus position calculation according to the change rate of the zoom lens position, ensuring accurate zoom tracking regardless of the speed of manual zoom operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the focus lens or correction lens is driven based on the current position of the zoom lens, then the control system is simple, but the focus state cannot be obtained when the zoom lens has already moved to another position
Solution Approach 1:
The patent applies preliminary action by determining the control target position of the correction lens in advance, considering the moving speed of the zoom lens. Instead of reacting to the current position alone, the system calculates where the zoom lens will be when the correction lens reaches its target, and sets the control target accordingly to ensure focus is maintained throughout the zoom operation.
2Ease of operation
If the zoom lens is electrically driven by power zoom, then the zoom speed is constant and control target position determination is easy, but the system cannot support manual zoom operations with variable speed
Solution Approach 1:
The patent implements feedback by detecting the actual moving speed of the zoom lens during manual operation and using this information to dynamically adjust the control target position of the correction lens. The system continuously monitors zoom lens position, calculates moving speed, and modifies the correction lens control accordingly, enabling accurate focus tracking regardless of whether the zoom operation is manual or automatic.
3Adaptability or versatility
If the user manually operates the zoom lens at variable speed, then the zoom operation is flexible, but the determination of control target position becomes difficult
Solution Approach 1:
The system performs preliminary calculation of the control target position by considering the detected moving speed of the zoom lens. Before the correction lens reaches its initial target position, the system has already determined the adjusted target position based on the zoom lens's current speed, ensuring that focus tracking remains accurate throughout the variable-speed manual zoom operation.
Data Source
AI summary
A lens barrel includes a correction lens to move for zoom tracking, a zoom lens driver to mechanically move a zoom lens according to an amount of turn of a zoom ring, a storage unit to store relational information associating a zoom lens position with a focus position of the correction lens, and a controller to control the correction lens driver. The controller determines a focus position of the correction lens corresponding to a position distant by a predetermined amount from a detected zoom lens position, by referring to the relational information, and controls the correction lens driver to drive the correction lens to a target position set to the determined focus position. A formula varying with the change rate of the zoom lens position is used to calculate the predetermined amount, and is set according to positions of the zoom lens and the focus lens.