SMA Actuator Assembly With Nested Wires for Compact OIS Motion
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Solution Overview
Problem
Existing actuator assemblies for optical image stabilization in portable devices face challenges in miniaturization and efficient movement of lens assemblies due to space constraints and friction issues, particularly when using shape-memory alloy (SMA) wires.
Innovation Solution
The actuator assembly employs SMA wires with flexible configurations, including stacked and nested arrangements, flexures, and coupling parts to minimize friction and space requirements, allowing independent control of movements in multiple directions while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If SMA wires are used in a conventional configuration, then the actuator assembly can provide stabilization force, but the assembly size becomes too large for miniaturized portable devices
Solution Approach 1:
The patent implements a nested configuration where the first and second lengths of SMA wires are coupled together in a stacked arrangement. The coupling part connects the end of the first length to the start of the second length, allowing the wires to be arranged in a compact nested structure rather than extending linearly. This nesting principle reduces the overall volume of the actuator assembly while maintaining the necessary stroke and stabilization performance.
Solution Approach 2:
The patent transitions from a linear one-dimensional arrangement of SMA wires to a three-dimensional stacked configuration. By coupling the first and second lengths in a nested arrangement with coupling parts positioned at different heights, the system utilizes vertical stacking to reduce the horizontal footprint, enabling miniaturization while preserving functional performance.
2Speed
If conventional bearing arrangements are used, then the moving platform can be supported, but friction prevents efficient movement in portable devices
Solution Approach 1:
The patent replaces conventional mechanical bearing systems with a flexure-based passive bearing arrangement. The flexure members provide the necessary support and movement guidance through elastic deformation rather than mechanical contact, eliminating friction losses associated with traditional bearings. This substitution enables more efficient movement while supporting the moving platform.
3Volume of moving object
If rigid wire configurations are used, then the SMA wires can provide sufficient force, but the assembly cannot achieve compact nested arrangement
Solution Approach 1:
The patent employs flexible wire configurations that can bend and conform to the nested arrangement. The SMA wires are designed with appropriate flexibility to allow the stacked configuration while maintaining their force-generating capability. The flexible nature of the wires enables them to be routed through the compact nested structure without compromising the actuation force required for stabilization.
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 enhances the range of movement and reduces friction, enabling efficient optical image stabilization with a more compact actuator assembly, suitable for miniaturized applications.
Implementation Method 1
The actuator assembly employs SMA wires with flexible configurations
Data Source
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AI summary
A shape memory alloy actuator assembly comprising: a support, wherein a first plane is defined with reference to the support; a movable part movable relative to the support along at least two different non-parallel directions in the first plane; plural units of shape memory alloy wire, each unit connected between the movable part and the support so as to be capable of being driven to produce movement in the at least two directions without applying any net torque to the movable part in the first plane; wherein at least one of the units comprises a series of two or more lengths of shape memory alloy wire including a first length and a second length, wherein the first and second lengths are orientated at a non-zero angle relative to each other and are coupled to each other such that, when the unit is driven, contraction of the first length causes a displacement of the second length that provides a contribution to movement of the movable part that is in addition to the contribution provided by contraction of the second length.