Camera Lens Focus Drive Control via Dynamic Speed Adjustment
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Solution Overview
Problem
Conventional camera systems face a trade-off between stopping accuracy and driving time for focus adjustment, with limited user-settable settings for focusing ring drive, leading to unpredictable performance in one-shot and AI servo modes, resulting in decreased frame speed and marginal performance.
Innovation Solution
An automatic focus adjustment apparatus and method that control acceleration/deceleration and driving time of the lens, allowing for optimum drive control of the focus operation member in both one-shot and AI servo modes by acquiring and transmitting the driving amount and permissible time, enabling precise drive control to satisfy the permissible time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If priority is given to stopping accuracy, then focus precision is improved, but driving time increases
Solution Approach 1:
The patent applies dynamics by making the driving speed of the focusing ring variable rather than constant. The control unit dynamically adjusts the driving speed based on the detected defocus amount and the current driving state. When the focusing ring is far from the target position, it drives at a higher speed; as it approaches the target, it gradually reduces speed. This dynamic speed adjustment allows the system to achieve both fast driving time and high stopping accuracy by optimizing the velocity profile throughout the driving process.
Solution Approach 2:
The patent changes the parameter of driving speed from a fixed value to a variable parameter that depends on the defocus amount and driving progress. By calculating an appropriate driving speed based on the magnitude of defocus and adjusting it during the driving process, the system optimizes the balance between driving time and stopping accuracy. This parameter change enables adaptive control that responds to different focusing conditions.
2Productivity
If driving speed of focusing ring is increased, then driving time is reduced, but stopping accuracy deteriorates
Solution Approach 1:
The system implements dynamic speed control where the driving speed of the focusing ring is continuously adjusted based on real-time feedback. The control unit calculates an appropriate driving speed considering the defocus amount and modifies it during operation. This allows high driving speeds to be maintained when far from the target (reducing overall driving time) while automatically reducing speed near the target position (maintaining stopping accuracy).
Solution Approach 2:
The patent employs feedback control by continuously monitoring the defocus amount and using this information to adjust the driving speed of the focusing ring. The control unit receives feedback about the current focusing state and modifies the driving parameters accordingly. This closed-loop control ensures that the system can drive quickly when needed while automatically slowing down to achieve precise stopping accuracy near the target position.
3Device complexity
If user-settable settings are limited to driving amount and driving speed, then device complexity is reduced, but adaptability to different modes deteriorates
Solution Approach 1:
The patent applies self-service by enabling the control unit to automatically calculate and determine the appropriate driving speed based on the detected defocus amount and driving conditions. Instead of requiring users to manually configure different speed parameters for different modes, the system autonomously optimizes the driving speed profile. This self-adjusting capability allows the system to adapt to both one-shot and AI servo modes effectively while keeping the user interface simple with limited settings.
Solution Approach 2:
The system changes the driving speed parameter dynamically based on the operating mode and defocus conditions, without requiring complex user configuration. The control unit automatically adapts the speed parameters according to the detected scenario, whether one-shot or AI servo mode. This automatic parameter adjustment provides mode-specific optimization while maintaining device simplicity.
Data Source
AI summary
An automatic focus adjustment method for transmitting, from a camera main body side to a lens side, a driving amount of a focus operation member configured to drive a lens, the automatic focus adjustment method includes, when a driving amount according to defocus of an object is transmitted, transmitting a driving permissible time of the focus operation member according to a control method of automatic focus adjustment as well. On the camera main body side, the driving permissible time is acquired according to the set control method of the automatic focus adjustment. On the lens side, drive control of the focus operation member is switched so that a driving time of the focus operation member satisfies the driving permissible time.