Image Stabilizer Driving Device Asymmetric Actuator Control
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Solution Overview
Problem
Image stabilizers using voice coil motors (VCM) face challenges in enlarging the movable amount of optical elements without increasing the diameter of the driving device, as larger magnets and coils are required, leading to increased size without proportional movable range.
Innovation Solution
A driving device with a dual actuator system, where each actuator has a coil and magnet arranged to face each other, and a control unit that adjusts electric currents based on position-specific coefficients and functions to optimize thrust and minimize device diameter, allowing for increased movable range without enlarging the device's diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the width of the magnet and the width of the coil are increased to increase the movable amount of the moving part, then the movable amount is improved, but the diameter of the driving device increases more than the addition of the movable amount
Solution Approach 1:
The patent applies asymmetry by intentionally offsetting the center of the voice coil from the center of the magnet. This asymmetric arrangement allows the voice coil to move in a circular path around the magnet center rather than along a straight line through it. The offset distance is specifically designed so that the thrust component in the moving direction remains maximized throughout the movement range, enabling larger movable amount without increasing the magnet and coil widths, thus resolving the contradiction between movable amount and device diameter.
Solution Approach 2:
The patent transitions from one-dimensional linear movement (through the magnet center) to two-dimensional circular movement (around the magnet center). By moving the voice coil in a circular path with radius equal to the offset distance, the system achieves larger effective movement range without increasing the radial dimensions of the magnet and coil, effectively resolving the size-movement contradiction.
2Length of moving object
If a single actuator with centered coil and magnet is used, then the structure is simple, but the movable amount is limited without increasing device diameter
Solution Approach 1:
The patent introduces dynamic control by varying the electric current supplied to the voice coil based on its position during circular movement. The control unit adjusts current magnitude and direction to maintain optimal thrust throughout the movement cycle, enabling precise control of the moving part's position and velocity. This dynamic control approach allows the single actuator to achieve functions that would otherwise require multiple actuators, resolving the contradiction between movable amount and device complexity.
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 effectively suppresses the enlargement of the device's diameter even when the movable amount of the optical element is increased, maintaining efficient image stabilization while keeping the device compact.
Implementation Method 1
a drive unit configured to have a first actuator and a second actuator each of which is provided with a coil arranged in one of the fixing part and the moving part and a magnet arranged in the other part so as to face the coil, and to give a thrust to the moving part so as to drive the moving part in the predetermined direction
Data Source
AI summary
A driving device that is capable of suppressing enlargement of diameter when a movable amount of a moving part increases. The driving device drives a moving part that is movably supported by a fixing part in a predetermined direction. A drive unit has first and second actuators each of which includes a coil arranged in one of the fixing part and moving part and a magnet arranged in the other part so as to face the coil, and gives a thrust to drive the moving part. A control unit controls the drive unit by controlling electric currents supplied to the coils of the first and second actuators in response to results obtained by multiplying first and second coefficients that vary in response to the position of the moving part to first and second control values obtained from first and second functions based on the position of the moving part, respectively.