Camera Module Actuator Dynamic Control Gain Adjustment
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Solution Overview
Problem
The reduction in thickness of mobile devices limits the movement range of camera module lens barrels, leading to increased rise time due to frictional forces and potential overshoot due to acceleration, especially when control gain is uniformly maintained.
Innovation Solution
An actuator system for camera modules that includes a magnet, a driving coil, a driving apparatus with a PID controller, and a position calculator, which dynamically adjusts the control gain based on error values to optimize movement, reducing the control gain during increased error and increasing it during decreased error, thereby reducing overshoot and rise time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the control gain is uniformly maintained in a camera module with limited movement range, then the system structure remains simple, but the rise time increases due to frictional force and overshoot may occur due to acceleration
Solution Approach 1:
The patent applies dynamics by transitioning from a static uniform control gain to a dynamic variable control gain that changes based on the lens barrel's movement state. The control gain is adjusted according to the error between target and actual positions, being larger when the error is large (to reduce rise time) and smaller when the error is small (to reduce overshoot and frictional effects), thereby optimizing performance throughout the movement range.
Solution Approach 2:
The patent implements parameter changes by modifying the control gain parameter based on the error value. The control gain is set to a first value when the error exceeds a threshold and to a second value (different from the first) when the error is within the threshold, allowing the system to adapt to different movement phases and resolve the contradiction between rise time and overshoot.
2Device complexity
If the control gain is uniformly maintained in a camera module with limited movement range, then the control system remains simple, but overshoot may occur due to acceleration
Solution Approach 1:
The system uses dynamic control gain adjustment to prevent overshoot. When the lens barrel approaches the target position (error within threshold), the control gain switches to a smaller value that reduces acceleration effects, thereby preventing overshoot and improving positioning reliability without requiring a complex multi-mode control structure.
Solution Approach 2:
By changing the control gain parameter based on the error magnitude, the system optimizes positioning accuracy. The control gain is reduced when the error is small to prevent excessive acceleration and overshoot, while maintaining a larger gain when the error is large to ensure timely response, thus resolving the contradiction between system simplicity and positioning reliability.
3Length of stationary object
If the movement range of the lens barrel is reduced to decrease device thickness, then the device becomes more compact, but frictional force increases leading to longer rise time
Solution Approach 1:
The patent compensates for the increased frictional force in limited movement ranges by dynamically adjusting the control gain. When the error is large (indicating the lens barrel is far from the target), a larger control gain is applied to overcome friction and reduce rise time, while maintaining device compactness through the inherent limited movement range design.
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 system effectively reduces overshoot and rise time by dynamically adjusting the control gain, enhancing the precision and efficiency of lens barrel movement in camera modules, even under limited movement ranges.
Implementation Method 1
a magnet, a driving coil facing the magnet, a driving apparatus including a driving circuit configured to apply a driving signal to the driving coil to move the magnet
Implementation Method 2
The position calculator may include a sensing coil configured to determine a frequency of the oscillation signal
Data Source
AI summary
An actuator of a camera module including a magnet, a driving coil facing the magnet, a driving apparatus including a driving circuit configured to apply a driving signal to the driving coil to move the magnet, and a position calculator configured to generate a feedback signal based on a current position of the magnet, wherein the driving apparatus is further configured to calculate an error value by comparing an input signal with the feedback signal, and to determine a control gain of a control signal provided to the driving circuit according to the error value, and wherein the control gain is reduced in response to an increase in the error value, and the control gain is increased in response to a decrease in the error value.