SMA Wire Optical Actuator for Thin Smartphone Zoom
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Solution Overview
Problem
The challenge is to develop a camera module for smartphones that can achieve a large-stroke zoom capability while maintaining a thin and lightweight design, as traditional motor-driven systems occupy too much space and periscope camera modules are difficult to miniaturize further due to the compact internal design of smartphones.
Innovation Solution
An optical actuator using shape memory alloy wires is employed, where the wires are arranged on the sides of a lens module to provide a consistent force along the optical axis, allowing the lens to move through expansion and contraction, with a periscope structure to reduce the camera module's size and prevent wire interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional motor-driven systems are used to achieve large-stroke zoom capability, then the zoom capability is improved, but the camera module volume increases
Solution Approach 1:
The patent replaces the traditional motor-driven mechanical system with a shape memory alloy (SMA) wire-based actuation system. The SMA wires expand and contract in response to temperature changes, directly driving the lens module along the optical axis without requiring a motor, gear mechanisms, or other complex mechanical components. This substitution dramatically reduces the camera module volume while maintaining large-stroke zoom capability.
Solution Approach 2:
The patent utilizes the temperature-dependent dimensional change parameter of shape memory alloy materials. By controlling the temperature of the SMA wires through electrical heating, the wires expand and contract to drive the lens module, converting thermal energy into mechanical motion. This parameter change enables compact actuation while achieving the required lens movement stroke.
2Volume of stationary object
If periscope camera modules are used to reduce volume, then the camera module size is reduced, but the internal design space becomes extremely limited
Solution Approach 1:
The patent segments the camera module into distinct functional zones: a fixed base structure, a movable lens module, and strategically positioned SMA wire groups. The wire groups are divided into multiple subsets arranged at different locations, each contributing to the overall lens actuation. This segmentation allows for optimized space utilization and simplified internal design within the compact periscope configuration.
Solution Approach 2:
The patent arranges SMA wire groups in three-dimensional space around the lens module, with wires positioned at different heights and locations. This spatial distribution in multiple dimensions allows the wires to converge on the lens from different directions, enabling compact packaging while maintaining effective actuation force and reducing interference between components.
3Volume of stationary object
If shape memory alloy wires are used to reduce volume, then the camera module volume is reduced, but wire interference and wear may occur
Solution Approach 1:
The patent employs asymmetric arrangement of SMA wire groups, with different numbers of wire groups positioned at different locations around the lens module. This asymmetric configuration optimizes the force distribution and minimizes interference between wires during lens movement. The asymmetric layout also ensures that wires follow optimal paths that reduce wear and improve reliability.
Solution Approach 2:
The patent introduces guiding structures and fixing devices as intermediaries between the SMA wires and the lens module. These intermediaries constrain the wires to specific movement paths, prevent direct contact and friction between wires, and reduce wear. The guiding structures act as mediators that maintain wire integrity while enabling smooth lens actuation.
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 solution significantly reduces the size of the optical actuator, enhances the stability of the lens module, and allows for a thinner camera module design, facilitating the installation of front cameras in smartphones with high screen-to-body ratios by increasing the driving force and preventing wire wear.
Implementation Method 1
the shape memory alloy wire has the property of expanding and contracting with temperature changes
Implementation Method 2
the shape memory alloy wire has the property of expanding and contracting with temperature changes
Data Source
AI summary
An optical actuator, including: a base; a lens module comprising two first side surfaces opposite each other; and a plurality of shape memory alloy wires forming two wire groups, the two wire groups being disposed on the two first side surfaces, respectively, wherein two ends of each shape memory alloy wire are fixed to a base-end fixing device and a lens-end fixing device, respectively; and the direction of the resultant force acting on the lens module by the two wire groups is consistent with the direction of the optical axis of the lens module, so that the lens module is driven to move along the direction of the optical axis of the lens module by means of expansion and contraction of the shape memory alloy wires of the two wire groups.