Buckle Arm SMA Actuator for Compact Z-Stroke
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Shape memory alloy (SMA) systems used in applications like auto-focusing drives face challenges due to their complexity, resulting in bulky designs with limited Z-stroke range and a large footprint, 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 designs with increased Z-stroke range and reduced footprint by using buckle arms and bimorph structures that move in the z-direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional SMA systems with moving assembly and support assembly are used, then the system can provide auto-focusing drive function, 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 independently actuated by separate SMA wires. Each buckle arm can move independently in the z-direction, allowing the system to achieve greater total Z-stroke range through coordinated movement of multiple segments rather than relying on a single large moving assembly.
Solution Approach 2:
The buckle arms are configured to move primarily in the z-direction (vertical dimension) rather than requiring lateral movement in the x-y plane. This dimensional change allows the actuator to achieve high Z-stroke range while maintaining a compact footprint, as the movement occurs perpendicular to the base plane where space is constrained.
2Duration of action of stationary object
If traditional SMA systems with bearing and flexure element are used, then the moving assembly can be supported for movement, but the system height increases and profile becomes large
Solution Approach 1:
Instead of supporting the moving assembly from below with bearings and flexure elements that extend vertically, the invention inverts the support approach by using buckle arms that pivot at their bases and move upward. The support function is achieved through the pivot points at the base level rather than through vertical support structures, thereby reducing the height clearance requirement.
Solution Approach 2:
The buckle arms function as flexible, thin structural elements that can bend and pivot at their bases. These thin-film-like components provide the necessary support and movement capability without requiring bulky bearing assemblies or thick flexure elements, thus minimizing the vertical height of the actuator.
3Ease of operation
If SMA wires are used to actuate the system, then electrical drive signals can be applied, but the system complexity increases
Solution Approach 1:
The buckle arm structure serves multiple functions simultaneously: it acts as the mechanical linkage, the pivot point serves as the bearing, and the arm itself provides both support and actuation surfaces. This multi-functionality reduces system complexity by eliminating separate components that would otherwise be needed for each function, while still allowing electrical drive signals to be applied to SMA wires for actuation control.
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 SMA actuators achieve a Z-stroke greater than 0.4 millimeters with a height of 2.2 millimeters or less in the de-actuated position, providing a compact footprint suitable for applications like autofocus systems, micro-fluidic pumps, 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
Shape memory alloy (SMA) systems have a moving assembly or structure that for example can be used in conjunction with a camera lens element as an auto-focusing drive.
Implementation Method 3
at least one bimorph actuator including a shape memory alloy material
Implementation Method 4
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.