Lens Apparatus Adaptive Focus Speed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional autofocus systems face challenges in quickly achieving an in-focus state, particularly on the wide-angle side where the depth of field is large, leading to prolonged focus lens movement and reduced focusing speed due to the dependence on defocus amount thresholds.
Innovation Solution
The proposed lens apparatus includes a focus detector, defocus amount calculator, driving amount calculator, and controller that adjust the focus lens driving speed based on calculated defocus and driving amounts, using two threshold values to quickly achieve focus on both telephoto and wide-angle sides by shifting between high and low speed driving modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the focus lens is driven at high speed to quickly achieve focus, then the focusing speed is improved, but the focus accuracy deteriorates due to passing through the in-focus point
Solution Approach 1:
The driving speed of the focus lens is dynamically adjusted based on the defocus amount. When the defocus amount is large, high speed driving is used for quick focusing. When the defocus amount becomes small (approaching the in-focus point), the driving speed is reduced to prevent passing through the in-focus point, thus maintaining focus accuracy while achieving fast focusing.
Solution Approach 2:
The control method changes the driving speed parameter based on the defocus amount threshold. By monitoring the defocus amount and adjusting the driving speed accordingly, the system achieves both fast focusing and accurate focus. The switching between high speed and low speed driving is based on changes in the defocus amount parameter.
2Measurement precision
If the focus lens is driven at low speed to maintain focus accuracy, then the focus accuracy is improved, but the focusing speed deteriorates
Solution Approach 1:
The system dynamically adjusts the driving speed based on the defocus amount. During the majority of the focusing process, high speed driving is used to maintain fast focusing. Only when the defocus amount becomes small (near the in-focus point) does the system switch to low speed driving to ensure accuracy, thus minimizing the impact on overall focusing speed while maintaining accuracy.
Solution Approach 2:
The focus lens driving process is divided into distinct phases: high speed driving phase (when defocus amount is large) and low speed driving phase (when defocus amount is small). This periodic switching between different driving speeds optimizes both focusing speed and accuracy.
3Device complexity
If a single threshold value is used for defocus amount to control driving speed, then the control simplicity is improved, but the focus performance deteriorates on both telephoto and wide-angle sides
Solution Approach 1:
Different threshold values are applied for different focusing scenarios (telephoto side vs. wide-angle side). The first threshold value is used for telephoto side focusing while the second threshold value is used for wide-angle side focusing. This local differentiation of control parameters optimizes focus performance for each specific condition while maintaining relatively simple control logic.
Solution Approach 2:
The control method changes the threshold value parameter based on the lens focal length. By selecting different threshold values corresponding to different focal lengths, the system achieves optimal focus performance across the entire zoom range without requiring complex adaptive control algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables rapid and accurate focus adjustment irrespective of the lens focal length, ensuring quick in-focus state attainment on both telephoto and wide-angle sides by optimizing driving speed control.
Implementation Method 1
beams coming from a subject through different exit pupil regions of an image taking lens are imaged onto a pair of line sensors, and a pair of image signals are obtained through photoelectric conversion performed on subject images, to thereby determine a relative position displacement amount of the pair of image signals thus obtained. Based on the displacement amount, a defocus amount of the subject is calculated
Implementation Method 2
a controller for controlling a driving of the focus lens, in which the controller controls a driving speed of the focus lens depending on the defocus amount calculated by the defocus amount calculation unit and the driving amount calculated by the driving amount calculation unit
Data Source
AI summary
A lens apparatus has an image pickup optical system including a focus lens and a zoom lens, a focus detector, a defocus amount calculating unit, and a controller. The focus detector detects a focus state of the image pickup optical system. The defocus amount calculation unit calculates a defocus amount based on the detected focus state. The controller calculates a driving amount necessary to drive the focus lens to a focus position based on the calculated defocus amount. The controller controls the driving of the focus lens. In particular, the controller controls a driving speed of the focus lens depending on the calculated defocus amount and the calculated driving amount.