SMA Wire Actuator for Tunable Lens Force and Volume Trade-off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical devices, such as camera modules in smartphones, face challenges in generating sufficient force for deforming elastic tunable lenses for focusing and image stabilization operations, with existing actuators like VCM and piezo-electric motors producing insufficient force for these applications.
Innovation Solution
An optical device utilizing shape memory alloy (SMA) wires to actuate a movable structure connected to an elastic lens, allowing precise and high-force deformation of the lens for focusing and image stabilization, with low power consumption and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional actuators (VCM or piezo-electric motors) are used to deform the elastic lens, then the device structure is simple and easy to manufacture, but the generated force is insufficient for effective lens deformation
Solution Approach 1:
The patent replaces conventional electromagnetic actuators (VCM) and piezo-electric motors with a shape memory alloy (SMA) based actuator system. The SMA wires convert thermal energy directly into mechanical work through phase transformation, generating sufficient force ( several hundred mN) to deform the elastic lens effectively, while avoiding the complexity of electromagnetic or piezo-electric actuator structures.
Solution Approach 2:
The patent utilizes the phase transformation temperature parameter of shape memory alloy to generate mechanical force. By controlling the temperature (through electrical heating or other means), the SMA wires transform between martensite and austenite phases, producing large reversible deformation and generating the required actuation force for lens deformation.
2Force
If larger forces are generated to deform the elastic lens effectively, then the focusing and image stabilization performance improves, but the device size and power consumption increase
Solution Approach 1:
The SMA-based actuator generates large forces ( several hundred mN) through phase transformation without requiring large mechanical structures. The wires can be made very thin and compact, and their force generation capability comes from the material's intrinsic phase transformation properties rather than from large electromagnetic coils or piezo-electric stacks, thus achieving high force in a compact volume.
Solution Approach 2:
By utilizing the phase transformation temperature parameter of SMA, the actuator achieves high force output from a compact structure. The phase transformation enables large reversible deformation in the wire itself, converting thermal energy directly into mechanical work without requiring large mechanical leverage or structural components.
3Force
If conventional actuators are used for lens actuation, then the device structure is compact, but the force generation capability is insufficient for elastic lens deformation
Solution Approach 1:
The SMA actuator utilizes phase transformation temperature parameter to generate force. By controlling the temperature cycling of the SMA wires, the system achieves large reversible deformation and high force output. The energy consumption is optimized by applying heat only during actuation phases and allowing passive cooling during return strokes, reducing overall power consumption compared to continuous electromagnetic actuation.
Solution Approach 2:
The SMA-based actuator operates through periodic heating and cooling cycles to achieve continuous actuation. The shape memory alloy wires are heated to transform from martensite to austenite phase for actuation, then cooled to return to martensite phase for reset, creating a periodic action that enables continuous focusing and image stabilization operations with reduced average power consumption.
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
Enables high-speed and precise focusing and image stabilization operations with low power consumption, suitable for compact camera modules, and electromagnetic immunity, avoiding interference from adjacent magnetic fields.
Implementation Method 1
one or more shape memory alloy (SMA) wires, wherein length changes of the one or more SMA wires cause a movement of the movable structure
Implementation Method 2
The SMA wires are operable to change their lengths, in particular by heating the SMA wires
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to an optical device for an optical system of a light transmitting or light receiving device. The optical device is suitable for a camera module, e.g. as used in a mobile device like a smartphone. The optical device comprises an elastic lens, a movable structure connected to the elastic lens, and one or more SMA wires coupled to the movable structure. Length changes of the one or more SMA wires cause a movement of the movable structure, and the movement of the movable structure causes a deformation of the elastic lens.