Shape Memory Alloy Camera Motor With Magnetic Anti-Eccentricity Centering
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Solution Overview
Problem
Conventional shape memory alloy motors used in camera modules suffer from significant eccentricity issues when powered off, affecting the appearance and yield of camera modules and mobile terminals.
Innovation Solution
Incorporation of an eccentricity-prevention magnetic assembly with magnetostatic forces and an elastic structure to ensure central axis alignment between the base and support base, even in a powered-off state, using a shape memory alloy actuator for driving in a powered-on state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a shape memory alloy motor is used to achieve AF and OIS functions, then the motor has advantages such as low costs, large thrust, long stroke, and no electromagnetic interference, but when the motor is powered off, the shape memory alloy wires get loose and the position and posture of the motor rotor become relatively free, resulting in a relatively large deviation between the center of the motor rotor and the central position of a motor stator
Solution Approach 1:
The patent applies preliminary action by pre-positioning the support base at the center of the base using magnetic attraction forces between magnetic assemblies before the shape memory alloy actuators are activated. This ensures that when power is off and actuators are relaxed, the rotor remains centered through the preliminary magnetic positioning, preventing eccentricity without requiring complex mechanical centering mechanisms.
Solution Approach 2:
The patent introduces magnetic assemblies as an intermediary mechanism between the base and support base. These magnetic assemblies create attractive forces that mediate the positioning relationship, holding the support base centered on the base when actuators are not active. This intermediary magnetic field solves the centering problem without direct mechanical contact or complex adjustment mechanisms.
2Device complexity
If the rotor is suspended only by shape memory alloy wires, then the motor structure is simplified, but the rotor position and posture become unstable when powered off due to gravity
Solution Approach 1:
The magnetic assemblies act as an intermediary force field that stabilizes the rotor position without requiring additional mechanical support structures. The magnetic attraction provides a continuous stabilizing force that counteracts gravity's effect on the suspended rotor, maintaining positional stability while preserving the simplified wire-suspension structure.
Solution Approach 2:
The patent replaces potential mechanical centering mechanisms with a magnetic field-based positioning system. Instead of using mechanical stops, guides, or adjustment mechanisms to maintain rotor position, the invention uses magnetic forces to achieve stable positioning, thereby maintaining structural simplicity while improving stability.
3Force
If shape memory alloy wires are used to drive the support base, then the motor achieves large thrust and long stroke, but significant eccentricity occurs when the motor is powered off
Solution Approach 1:
The magnetic assemblies provide a counteracting force that balances the eccentricity-tending forces when the shape memory alloy actuators are relaxed. The magnetic attraction creates a restoring force that pulls the support base back to the centered position, counterbalancing the gravitational and inertial forces that cause eccentricity during powered-off states.
Solution Approach 2:
The magnetic positioning system performs preliminary centering of the support base before actuator activation. This preliminary magnetic positioning ensures that the rotor starts from a centered position and returns to center when actuators are relaxed, preventing the accumulation of eccentricity errors while maintaining the high thrust capability of the shape memory alloy wires.
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
Reduces the possibility of eccentricity, improves product yield, and maintains structural integrity and functionality of camera modules and mobile terminals.
Implementation Method 1
the shape memory alloy actuator is configured to drive the support base to move relative to the base
Implementation Method 2
when the motor is in a powered-off state, a first central axis of the base coincides with a second central axis of the support base under the action of magnetostatic forces between the first eccentricity-prevention member and the second eccentricity-prevention member
Data Source
AI summary
A system includes a motor, a camera module, and a mobile terminal. The motor includes a base, a support base, and a shape memory alloy actuator. The shape memory alloy actuator is connected between the base and the support base, and the shape memory alloy actuator is configured to drive the support base to move relative to the base.