SMA Actuator Buckle Arms Radial Z-Stroke
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Solution Overview
Problem
Shape memory alloy (SMA) systems for auto-focusing drives, such as those used in camera lens elements, face challenges due to complexity, resulting in bulky designs with large footprints and limited Z-stroke range, failing to provide a compact, low-profile solution with high actuation height.
Innovation Solution
The development of SMA actuators incorporating buckle and bimorph actuators with SMA wires, which utilize electrical signals to actuate and de-actuate, allowing for compact footprints and increased Z-stroke range by leveraging the properties of shape memory alloys to change length and move components efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional SMA systems with moving assembly and bearing are used, then the system can achieve movement functionality, but the system becomes bulky with large footprint and limited Z-stroke range
Solution Approach 1:
The actuator is divided into multiple buckle arms (typically four) that are segmented and arranged radially around a central axis. Each buckle arm independently responds to SMA wire actuation, allowing the moving assembly to achieve cumulative Z-stroke displacement while maintaining a compact radial footprint. The segmentation enables parallel actuation mechanisms that multiply the effective stroke without increasing overall footprint.
Solution Approach 2:
The design transitions from linear actuation to radial/dimensional actuation by arranging buckle arms in a radial configuration around a central axis. The SMA wires are positioned to actuate the buckle arms from the sides, converting lateral forces into vertical Z-stroke movement. This dimensional transformation allows high stroke range to be achieved within a small planar footprint by utilizing the third dimension (height) more effectively.
2Ease of operation
If traditional SMA systems with multiple components are used, then the system can provide actuation functionality, but the system complexity increases resulting in bulky design
Solution Approach 1:
Multiple functional components are merged into integrated assemblies: the buckle arms combine structural support, actuation response, and motion transmission functions; the moving assembly integrates the lens mounting, actuation interface, and positional control; the SMA wires directly couple electrical actuation signals to mechanical movement. This merging reduces the number of separate components and simplifies the overall system architecture while maintaining actuation performance.
Solution Approach 2:
The buckle arms serve multiple functions simultaneously: they provide structural support for the moving assembly, act as the primary actuation elements that convert SMA wire contraction to vertical motion, and function as mechanical linkages that transmit force efficiently. The moving assembly itself serves as both the platform for lens mounting and the interface for receiving actuation forces from multiple buckle arms, reducing the need for separate transmission components.
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 SMA actuators achieve a Z-stroke greater than 0.4 millimeters with a height of 2.2 millimeters or less, providing a compact footprint suitable for applications like autofocus systems, micro-fluidic pumps, and haptic feedback devices, while maintaining high actuation performance.
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 suspension is actuated by applying electrical drive signals to the SMA wires.
Implementation Method 3
at least one bimorph actuator including a shape memory alloy material
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.