Autofocus Lens Settling Time Reduction via PID Gain Variation
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Solution Overview
Problem
Conventional autofocus systems in electronic devices experience a significant settling time due to mechanical oscillations, which delays the lens's ability to reach the target position, thereby limiting the frame rate of image capture.
Innovation Solution
The proposed solution involves gradually increasing the target position, varying the gain of a PID controller, and introducing a kick pulse to the position signal to reduce the settling time of the lens, utilizing a combination of actuators, sensors, and image signal processing to control the lens's movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional autofocus control is used, then the lens reaches the target position, but the settling time is long due to mechanical oscillations
Solution Approach 1:
The system performs preliminary actions by gradually increasing the target position in steps rather than jumping directly to the final position. This prevents large oscillations from occurring in the first place, allowing the lens to settle faster at each intermediate position before moving to the next step, thereby reducing overall settling time and enabling higher frame rates
Solution Approach 2:
The system dynamically adjusts the target position based on the lens's current state and response characteristics. By making the target position adaptive and incremental rather than fixed and abrupt, the system optimizes the control process to minimize oscillations and settling time, improving both response speed and frame rate
2Speed
If the target position is increased abruptly, then the lens responds quickly, but mechanical oscillations increase and settling time increases
Solution Approach 1:
The target position adjustment is segmented into multiple smaller steps rather than a single large jump. The system divides the total position change into incremental increments, applying them sequentially. This segmentation reduces the amplitude of mechanical oscillations at each step while maintaining cumulative progress toward the final position, achieving both speed and stability
Solution Approach 2:
The system applies periodic position adjustments with carefully controlled intervals. By timing the incremental position changes to allow partial settling between steps, the system creates a rhythmic control pattern that prevents oscillations from accumulating and extending the settling time, thereby improving both response speed and mechanical stability
Data Source
AI summary
Various embodiments of the present technology may comprise a method and apparatus for autofocus. In various embodiments, the methods and apparatus may decrease a settling time of a lens by increasing the target position gradually, varying the gain of a PID controller, and adding a kick pulse to a position signal.