SMA Actuator Buckle and Bimorph Designs for Compact Z-Stroke
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Solution Overview
Problem
Shape memory alloy (SMA) systems for actuators, such as those used in camera lens autofocus, face challenges with complexity leading to bulky designs and limited Z-stroke range in compact, low-profile applications.
Innovation Solution
The development of SMA actuators incorporating buckle and bimorph designs with compact footprints, utilizing SMA wires and materials to achieve high Z-stroke movement with a reduced footprint, including buckle actuators with laminate hammocks and bimorph actuators with center feed configurations for efficient actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional SMA systems use multiple components including flexure elements, bearing assemblies, and separate support structures, then the system can achieve reliable actuation, but the device complexity increases resulting in bulky designs with large footprint and height clearance requirements
Solution Approach 1:
The patent merges the flexure element and support assembly into a single integrated SMA actuator structure. The flexure element is directly coupled to the support assembly without requiring separate bearing assemblies or additional support structures, thereby reducing component count and simplifying the overall system while maintaining actuation reliability
Solution Approach 2:
The integrated SMA actuator structure performs multiple functions simultaneously: the flexure element provides both structural support and actuation capability, while the SMA wire serves both as a structural component and an actuator. This multi-functionality eliminates the need for separate specialized components, reducing device complexity
2Stability of the object's composition
If traditional SMA systems use conventional designs with multiple components, then the system can provide stable support, but the footprint area increases making it unsuitable for compact applications
Solution Approach 1:
The patent employs a nested configuration where the flexure element is positioned within the support assembly structure, and the SMA wire is integrated within the flexure element. This nesting arrangement allows multiple components to occupy the same spatial envelope, significantly reducing the overall footprint area while maintaining structural stability
Solution Approach 2:
The patent transitions from a planar, two-dimensional arrangement of components to a three-dimensional integrated structure. The flexure element and support assembly are configured in vertical and lateral dimensions rather than requiring extensive horizontal space, thereby reducing footprint area while preserving structural stability through spatial optimization
3Length of moving object
If traditional SMA systems use conventional actuator designs, then the system can provide adequate Z-stroke range, but achieving high Z-stroke with compact footprint and low profile height is not possible
Solution Approach 1:
The patent utilizes curved configurations of the flexure element and SMA wire to achieve enhanced Z-stroke movement. The curved geometry allows the flexure element to deflect and return more effectively, converting smaller input movements into larger output Z-stroke while maintaining a compact overall volume
Solution Approach 2:
The patent optimizes geometric parameters such as the thickness, length, and curvature radius of the flexure element and SMA wire to maximize Z-stroke output. By carefully selecting and adjusting these dimensional parameters, the actuator achieves high Z-stroke range without proportionally increasing the overall volume, maintaining a compact profile
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
These designs enable SMA actuators to achieve a Z-stroke greater than 0.4 mm with a height of 2.2 mm or less, providing a compact footprint suitable for applications like autofocus and optical image stabilization, while maintaining high actuation efficiency.
Implementation Method 1
Each of the SMA wires has one end attached to the support assembly, and an opposite end attached to the moving assembly. The suspension is actuated by applying electrical drive signals to the SMA wires.
Implementation Method 2
The SMA wires are heated by electrical drive signals to induce phase change from martensite to austenite, causing the wire to contract and actuate the buckle arms.
Implementation Method 3
at least one bimorph actuator including a shape memory alloy material. The bimorph actuator attached to the base.
Implementation Method 4
bimorph actuators with center feed configurations for efficient actuation
Data Source
AI summary
SMA actuators and related methods are described. One embodiment of an actuator includes a base; a plurality of buckle arms; and at least a first shape memory alloy wire coupled with a pair of buckle arms of the plurality of buckle arms. Another embodiment of an actuator includes a base and at least one bimorph actuator including a shape memory alloy material. The bimorph actuator attached to the base.