Actuator Assembly with Segmented Flexures for OIS
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Solution Overview
Problem
Existing actuator assemblies for optical image stabilization in camera modules require high driving forces and significant displacements to tilt the camera module, which can be mechanically complex and inefficient.
Innovation Solution
An actuator assembly featuring a bearing arrangement with first to fourth flexures and four lengths of shape memory alloy wires, configured to convert lateral forces into tilting motion, reducing the required driving forces and displacements, and allowing for tilting about non-parallel axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SMA wire actuation is used to tilt the camera module, then the module can be stabilized for OIS, but high driving forces and significant displacements are required which makes the mechanical design complex
Solution Approach 1:
The flexure is segmented into multiple compliance features (first compliance feature, second compliance feature, third compliance feature) that independently contribute to different aspects of motion control. This segmentation allows each feature to be optimized for specific compliance requirements, reducing overall mechanical complexity while maintaining stabilization performance.
Solution Approach 2:
The flexure transitions from a rigid structure to a dynamic structure with controlled compliance characteristics. By incorporating compliance features that enable selective deformation in different directions, the system adapts its mechanical properties to reduce driving forces while maintaining OIS functionality.
2Reliability
If conventional SMA wire actuation is used to tilt the camera module, then the module can be stabilized for OIS, but high driving forces and significant displacements are required which reduces efficiency
Solution Approach 1:
The flexure's geometric parameters are changed by incorporating specific compliance features that modify its mechanical properties. These parameter changes enable the flexure to achieve the required tilting motion with reduced driving forces, improving actuation efficiency while maintaining OIS performance.
Solution Approach 2:
The patent replaces a purely mechanical rigid linkage system with a compliant mechanism that utilizes elastic deformation. This substitution reduces the mechanical advantage requirements and driving forces needed, thereby improving efficiency while achieving the same stabilization effect.
3Force
If the flexure has high compliance to lateral displacement, then the required driving forces are reduced, but the displacement of the second part other than tilting increases
Solution Approach 1:
Different regions of the flexure are assigned different compliance characteristics through localized compliance features. The first compliance feature provides lateral compliance to reduce driving forces, while the second and third compliance features constrain unwanted lateral displacements, achieving both goals simultaneously through spatially varying properties.
Solution Approach 2:
The flexure employs asymmetric compliance features that provide different compliance levels in different directions. This asymmetry allows the structure to be soft in the direction of desired tilting motion while remaining stiff in directions that would cause unwanted lateral displacement, resolving the contradiction between force reduction and displacement 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
The solution reduces the forces and displacements needed for tilting, simplifies the mechanical design, and enhances the efficiency of optical image stabilization in camera modules by utilizing the shape memory alloy wires to generate forces and torques for tilting the camera module.
Implementation Method 1
The drive arrangement includes four lengths of shape memory alloy wire. The four lengths of shape memory alloy wire are coupled to the second part and to the first part.
Implementation Method 2
The bearing arrangement includes first to fourth flexures arranged about a primary axis passing through the actuator assembly. The bearing arrangement is configured to convert lateral force(s) normal to the primary axis generated by the drive arrangement into tilting of the second part about the first and/or second axes.
Data Source
AI summary
An actuator assembly (4001) includes a first part (4002), a second part (4004), a bearing arrangement (4003) and a drive arrangement (4005). The bearing arrangement (4003) includes first to fourth flexures (40151, 40152, 40153, 40154) arranged about a primary axis (4009) passing through the actuator assembly (4001). The bearing arrangement (4003) supports the second part (4004) on the first part (4002). The second part (4004) is tiltable about first and/or second axes (4011, 4012) which are not parallel and which are perpendicular to the primary axis (4009). The drive arrangement (4005) includes four lengths of shape memory alloy wire (40101, 40102, 40103, 40104). The four lengths of shape memory alloy wire (40101, 40102, 40103, 40104) are coupled to the second part (4004) and to the first part (4002). The bearing 15 arrangement (4003) is configured to convert lateral force(s) normal to the primary axis (4009) generated by the drive arrangement (4005) into tilting of the second part (4004) about the first and/or second axes (4011, 4012). Each of the first to fourth flexures (40151, 40152, 40153, 40154) has a first end (4016) connected to the first part (4002) and a second end (4017) connected to the second part (4004). Each of the first to fourth flexures (40151, 40152, 40153, 40154) includes a feature (1016) configured to increase a first compliance of that flexure (40151, 40152, 40153, 40154) to displacement of the respective second end (4017) towards the respective first end (4016). The first compliance is less than a second compliance of that flexure (40151, 40152, 40153, 40154) to 25 displacement of the respective second end (4017) parallel to the primary axis (4009).