MEMS Actuator Flexure Design for Shock Resistance
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Solution Overview
Problem
Miniature cameras in electronic devices face challenges in reducing size while maintaining shock resistance, as smaller components are more delicate and prone to damage from rough handling.
Innovation Solution
The use of MEMS actuators with a movable and fixed frame structure, incorporating torsional and hinge flexures to provide high lateral stiffness and low rotational stiffness, allowing for precise motion control and shock absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of miniature cameras is reduced, then the size of electronic devices is reduced, but the shock resistance deteriorates
Solution Approach 1:
The actuator is divided into separate functional components: a movable frame, a fixed frame, torsional flexures, and hinge flexures. This segmentation allows each component to be optimized for its specific function while collectively providing shock resistance in a compact package.
Solution Approach 2:
The flexures are designed with specific geometric parameters (thickness, length, width) that control their stiffness characteristics. By adjusting these parameters, the flexures provide high lateral stiffness for positioning accuracy while maintaining low rotational stiffness for shock absorption, resolving the contradiction between size and shock resistance.
2Volume of moving object
If the size of miniature cameras is reduced, then the size of electronic devices is reduced, but the delicacy of components increases making them more prone to damage
Solution Approach 1:
The patent uses flexible hinge flexures and torsional flexures made from thin film materials (such as silicon nitride or polysilicon) that are deposited and patterned using standard MEMS fabrication processes. These thin film flexures provide the necessary mechanical compliance and shock absorption while maintaining a miniaturized form factor.
Solution Approach 2:
The actuator employs composite structures combining different materials with complementary properties: piezoelectric materials for actuation, flexible polymer or thin film materials for shock absorption in the flexures, and rigid materials for the frames. This composite approach enables small size while maintaining component durability.
3Manufacturing precision
If high lateral stiffness is provided between outer frame and movable frame, then positioning precision is improved, but rotational stiffness increases reducing motion control
Solution Approach 1:
The flexure design implements local quality by creating regions of high stiffness (lateral direction for positioning) and low stiffness (rotational direction for motion control) within the same component. The hinge flexure has a geometry that is stiff laterally but compliant rotationally, while the torsional flexure provides lateral support with controlled rotational characteristics.
Solution Approach 2:
The combination of hinge and torsional flexures creates a dynamic system where the movable frame can rotate with low resistance for motion control while maintaining high lateral positioning precision. The flexures allow the system to adapt its stiffness characteristics based on the direction and type of motion required.
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 enables the creation of smaller, more robust miniature cameras with enhanced shock resistance and improved motion control, suitable for various electronic devices like cellular telephones and surveillance devices, while reducing manufacturing costs and improving quality.
Implementation Method 1
At least one torsional flexure and at least one hinge flexure can cooperate to provide comparatively high lateral stiffness between the outer frame and the movable frame and can cooperate to provide comparatively low rotational stiffness between the outer frame and the movable frame
Data Source
AI summary
A device can have an outer frame and an actuator. The actuator can have a movable frame and a fixed frame. At least one torsional flexure and at least one hinge flexure can cooperate to provide comparatively high lateral stiffness between the outer frame and the movable frame and can cooperate to provide comparatively low rotational stiffness between the outer frame and the movable frame.