Actuator Control via Back EMF Detection for Lens Settling
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Solution Overview
Problem
Autofocus systems in electronic devices face increased settling time due to back electromotive force (EMF) induced by external vibrations, affecting the precision and efficiency of lens positioning in imaging systems.
Innovation Solution
Implementing digital signal processing functions to detect back EMF and compute countermeasure values, which are used to generate drive signals that reduce ringing and facilitate faster settling times by adjusting the magnitude and direction of the drive signal during actuator operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If digital signal processing functions are implemented to detect back EMF and compute countermeasure values, then settling time is reduced, but device complexity increases
Solution Approach 1:
The system implements feedback by detecting the back EMF signal generated by the actuator and using this information to compute countermeasure values. The controller continuously monitors the back EMF and adjusts the drive signal accordingly, creating a closed-loop control system that actively compensates for vibrations and reduces settling time.
Solution Approach 2:
The patent introduces digital signal processing functions as an intermediary between the actuator and the control system. This intermediary processes the back EMF signal to extract vibration information and generates countermeasure values, effectively mediating the control process to reduce settling time without directly modifying the actuator hardware.
2Loss of time
If countermeasure drive signals are applied to reduce ringing, then settling time decreases, but energy consumption increases
Solution Approach 1:
The system applies countermeasure drive signals in a periodic manner, activating them only when back EMF indicates vibrations are present. The controller monitors the back EMF signal and applies corrective signals during specific periods when needed, rather than continuously, thereby reducing energy consumption while maintaining fast settling performance.
Solution Approach 2:
The controller dynamically changes the parameters of the drive signal based on the detected back EMF conditions. When vibrations are detected, the system adjusts the magnitude and timing of the countermeasure signal; when no vibrations are present, the system reduces or eliminates the countermeasure signal, optimizing energy usage according to actual operating conditions.
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
The solution significantly reduces the settling time of the actuator, allowing the lens to reach the target position more quickly, as demonstrated by a convergence time reduction from approximately 1 second to 150 milliseconds.
Implementation Method 1
the settling time of the actuator may be greater than desired due to the back electromotive force (back EMF) that is induced by external vibrations on the actuator
Data Source
AI summary
Various embodiments of the present technology may comprise a method and apparatus for actuator control. The methods and apparatus may comprise various digital signal processing functions to detect a back EMF (electromotive force) and compute a countermeasure value to reduce ringing. The methods and apparatus for actuator control may apply a drive signal corresponding to the countermeasure value. The magnitude and direction of the drive signal provided at particular times during operation may facilitate a shorter settling time.