Compact SMA Actuator Using Segmented Wire for Large Stroke
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Solution Overview
Problem
Existing SMA actuators in image capture devices, such as cameras, face limitations in achieving a large enough displacement to move optical elements like IR filters due to the small contraction (about 8%) of shape memory alloy materials, which requires long wire lengths and increases the actuator size and cost, making them unsuitable for compact applications like smartphones.
Innovation Solution
A compact SMA actuator design that mechanically couples two segments of SMA actuator wire around a corner of a static component, allowing their contractions to additively combine and generate a larger output stroke, thereby moving a moveable component without the need for long wire lengths, utilizing a static component with corner elements like flexures or crimp components to amplify the displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long lengths of SMA actuator wire are used to achieve large displacement, then the output stroke is improved, but the actuator size and cost increase
Solution Approach 1:
The SMA actuator wire is divided into multiple segments that are mechanically coupled together in series around corners of a static component. Each segment contributes its contraction to the total displacement, allowing multiple segments to work in unison to achieve a larger output stroke without requiring a single excessively long wire, thus reducing overall actuator size.
Solution Approach 2:
The SMA wire segments are arranged around corners of a static component, utilizing the corner geometry to amplify displacement. The wire segments traverse multiple dimensions (sides and corners of the static component), converting the small linear contractions of each segment into a larger cumulative displacement in the output direction.
2Length of moving object
If long lengths of SMA actuator wire are used to achieve large displacement, then the output stroke is improved, but the manufacturing cost increases
Solution Approach 1:
By segmenting the SMA wire into multiple portions that can be mechanically coupled together, the design reduces the total length of SMA material required compared to a single long wire approach. This segmentation allows for more efficient material utilization and potentially lower manufacturing costs while achieving the same output stroke.
3Reliability
If the contraction of SMA material is utilized to move optical elements, then the actuator function is improved, but the displacement is insufficient for large stroke requirements
Solution Approach 1:
Multiple SMA wire segments are mechanically coupled together in series, merging their individual contraction effects. The displacement of each segment combines in an additive manner to generate a larger total contraction, thereby achieving the required large stroke for moving optical elements while maintaining the reliable SMA actuation mechanism.
Solution Approach 2:
The arrangement of SMA wire segments around corners of a static component utilizes geometric configuration to amplify displacement. The wire segments traverse multiple dimensions, converting the small linear contractions of each segment into a larger cumulative displacement in the output direction, thereby achieving sufficient stroke for optical element movement.
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
This design achieves a significant output stroke with minimal height, suitable for compact devices, enabling the movement of optical elements like IR filters in and out of the optical path, addressing the size and cost constraints of traditional SMA actuators.
Implementation Method 1
at least one shape memory alloy (SMA) actuator wire coupled to the static component and the moveable component, where a first segment of SMA actuator wire is provided on a first side of the static component, and a second segment of SMA actuator wire is provided on a second side of the static component
Implementation Method 2
contraction of the segments of SMA actuator wire additively combine to generate a total contraction that moves the moveable component
Data Source
AI summary
Broadly speaking, embodiments of the present techniques provide an actuator that comprises segments of shape memory alloy (SMA) actuator wire that can be used to deliver a relatively large output stroke. In particular, two segments of SMA actuator wire may be mechanically coupled together around a corner of a static component of the actuator such that a displacement (e.g. contraction) of one segment causes a displacement (e.g. contraction) of the other segment. In this way, the displacement of each segment combines in an additive manner to generate a large output stroke that is able to move a moveable component of the actuator.