Multi-Stage SMA Actuator for Extended Stroke Length
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Solution Overview
Problem
Existing actuator assemblies using shape-memory alloy (SMA) wires for optical image stabilization in cameras, particularly in portable devices, face limitations in achieving extended stroke lengths, which restricts the range of movement and effectiveness in miniaturized camera systems.
Innovation Solution
A multi-stage SMA actuator assembly with two sets of non-collinear SMA wires in each plane, allowing movement in two different non-parallel directions, and a bearing system with biasing springs and magnets to enhance the range of movement without applying net torque, enabling extended lateral movement perpendicular to the optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single set of SMA wires is used to move the lens assembly, then the device structure is simple, but the stroke length and range of movement are limited
Solution Approach 1:
The actuator assembly is divided into multiple independent sub-assemblies (first sub-assembly with first set of SMA wires, second sub-assembly with second set of SMA wires). Each sub-assembly contributes to the overall movement, enabling extended stroke length through combined displacement while maintaining modular simplicity in each segment.
Solution Approach 2:
The patent introduces movement in multiple dimensions by adding a second set of SMA wires that move the lens assembly in directions non-parallel to the first set. This multi-dimensional approach extends the total range of movement beyond what a single planar actuator could achieve.
2Adaptability or versatility
If multiple sets of SMA wires are used to extend stroke length, then the movement range is improved, but the device complexity increases
Solution Approach 1:
The actuator assembly is divided into multiple independent sub-assemblies (first sub-assembly with first set of SMA wires, second sub-assembly with second set of SMA wires). Each sub-assembly contributes to the overall movement, enabling extended stroke length through combined displacement while maintaining modular simplicity in each segment.
Solution Approach 2:
The bearing system is designed to support multiple functions: it bears the moving platform on the support platform, allows tilting motion, and works with multiple sets of SMA wires. This multi-functional design reduces the need for separate components for each function, thereby managing complexity while enhancing movement versatility.
3Reliability
If the lens assembly is constrained to move only in one plane, then the structure is simpler, but the optical image stabilization effectiveness is reduced
Solution Approach 1:
The patent introduces movement in multiple dimensions by adding a second set of SMA wires that move the lens assembly in directions non-parallel to the first set. This multi-dimensional approach extends the total range of movement beyond what a single planar actuator could achieve, improving OIS effectiveness.
Solution Approach 2:
The bearing system allows the moving platform to tilt dynamically during operation. This dynamic capability enables the lens assembly to adapt its orientation and movement path in real-time, enhancing stabilization effectiveness while maintaining a relatively simple structural design through the use of passive tilting rather than active control mechanisms.
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 provides a longer stroke length and improved movement range in the x-y plane, enhancing optical image stabilization capabilities in miniaturized camera systems by combining the movements of multiple SMA wire sets and utilizing a bearing system for stable support.
Implementation Method 1
The lateral movement of the lens assembly 3 is achieved by selective heating of the SMA wires 27
Implementation Method 2
an actuator assembly (2) including a support platform (21), a moving platform (23) that supports a lens assembly (3), shape memory alloy (SMA) wires (27) connected to the support platform (21) and the moving platform (23)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A shape memory alloy actuator assembly (2) is disclosed. The actuator assembly comprises a support (21), a first stage (22) moveable in at least two different non-parallel directions in a first plane relative to the support, a first set of at least two shape memory alloy wires (271) configured to move the first stage in the first plane, a second stage (23) moveable in at least two different non-parallel in a second plane parallel to or coplanar with the first plane relative to the first stage, and a second set of at least two shape memory alloy wires (272) configured to move the second stage in the second plane. The first stage is coupled to the support via the first set of shape memory alloy wires and the second stage is coupled to the first stage via the second set of shape memory alloy wires such that movement of the second stage in the second plane with respect to the support is a combination of movement of the first stage relative to support and the second stage relative to the first stage.