MEMS Autofocus Actuator Piezoelectric Motion Stops
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Solution Overview
Problem
Existing MEMS actuators face challenges in effectively limiting motion, particularly out-of-plane motion, in MEMS piezoelectric autofocus actuators, which is crucial for maintaining precise positioning and preventing unwanted movement.
Innovation Solution
The integration of piezoelectric motion stops and snubbers within the MEMS piezoelectric autofocus actuator, which includes motion stop subframes, deployment locks, and piezoelectric hinges, allows for precise control of motion by restricting out-of-plane motion along the Z-axis and limiting in-plane motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion limiting features are integrated into the MEMS actuator, then motion control precision is improved, but device complexity increases
Solution Approach 1:
The motion limiting features are integrated directly into the MEMS actuator structure by forming the motion stop subframe, deployment lock spring, deployment lock, deployment hinge, and locking block as a unified assembly that moves with the moving stage. This integration eliminates the need for separate motion limiting devices while providing precise out-of-plane motion restriction.
Solution Approach 2:
The deployment lock mechanism is nested within the motion stop subframe structure, with the deployment lock spring and deployment lock positioned inside the actuator body. The locking block is nested within the motion control system, allowing it to engage with the moving stage when deployed. This nested arrangement minimizes the overall device footprint while maintaining full motion limiting functionality.
2Manufacturing precision
If piezoelectric motion stops are integrated to restrict out-of-plane motion, then positioning accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The motion limiting system is segmented into distinct functional components: the motion stop subframe provides structural support, the deployment lock spring provides actuation force, the deployment lock controls deployment timing, the deployment hinge enables rotation, and the locking block provides the actual motion restriction. This segmentation allows each component to be optimized independently while simplifying the overall manufacturing process through modular assembly.
Solution Approach 2:
The piezoelectric hinges utilize the piezoelectric effect to change their mechanical properties based on applied voltage. When voltage is applied, the piezoelectric material undergoes dimensional changes that cause the hinge to rotate, deploying the locking block to restrict motion. This parameter-based control allows precise positioning without complex mechanical actuation mechanisms, improving positioning accuracy while maintaining manufacturing feasibility.
3Reliability
If deployment locks and springs are used to hold the motion stops, then motion restriction reliability is improved, but device complexity increases
Solution Approach 1:
The deployment lock spring automatically engages the deployment lock with the deployment pad when the locking block reaches the deployed position, holding it in place without requiring additional actuation mechanisms. The piezoelectric hinges also provide self-latching behavior where the applied voltage maintains the deployed position, and removing the voltage returns the system to its initial state. This self-service mechanism ensures reliable motion restriction while minimizing the number of additional components needed.
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 precise control of the moving stage's position, restricts unwanted motion, and enhances the overall performance and reliability of MEMS piezoelectric autofocus actuators by ensuring accurate and stable motion control.
Implementation Method 1
one or more piezoelectric hinges connected to the deployment pad; and a locking block connected to the one or more piezoelectric hinges, wherein the locking block is actuatable via the one or more piezoelectric hinges
Implementation Method 2
a plurality of piezoelectric bending elements configured to deform the motion control system and thereby control a precise position of the moving stage relative to the fixed stage
Implementation Method 3
a deployment lock spring connected to the motion stop subframe; a deployment lock connected to the deployment lock spring
Data Source
AI summary
A micro-electrical-mechanical system (MEMS) piezoelectric autofocus actuator includes: a fixed stage that is stationary; a moving stage that is movable along a travel direction (Z-axis); a motion control system coupling the fixed stage to the moving stage and including motion control springs; piezoelectric bending elements configured to deform the motion control system and thereby control a precise position of the moving stage relative to the fixed stage; and integrated piezoelectric motion stops that are actuatable to restrict out-of-plane motion of the moving stage along the travel direction (Z-axis). In another example, a MEMS piezoelectric autofocus actuator includes integrated motion limiting snubbers configured to limit in-plane motion of the moving stage; integrated motion stoppers configured to restrict out-of-plane motion of the moving stage along the travel direction (Z-axis); and assembled motion stoppers disposed in assembly slots and configured to restrict out-of-plane motion of the moving stage along the travel direction (Z-axis).