Piezoelectric MEMS Mirror Tilting About Two Axes
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Solution Overview
Problem
Existing microelectromechanical mirror devices, particularly those of the vector-scanner type, face challenges with high operating voltages and power consumption in electrostatic and electromagnetic actuation systems, while piezoelectric actuation systems offer lower voltages and power consumption but are not optimized for devices requiring tiltable structures to assume four different quasi-static positions.
Innovation Solution
A microelectromechanical device with a piezoelectrically driven actuation structure, featuring a tiltable structure that can rotate about two axes due to the rotation of lever elements, which are elastically coupled to the actuation structure, allowing for efficient and low-power tilting movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electrostatic or electromagnetic actuation systems are used for microelectromechanical mirror devices, then the mirror structure can be actuated to rotate about two axes, but the operating voltages and power consumption become high
Solution Approach 1:
The patent replaces electrostatic or electromagnetic actuation systems with a piezoelectric actuation system. The piezoelectric material converts electrical signals directly into mechanical deformation, eliminating the need for complex electrostatic or electromagnetic fields while reducing power consumption and operating voltages.
Solution Approach 2:
The patent changes the actuation mechanism from high-voltage electrostatic/electromagnetic fields to low-voltage piezoelectric actuation. By utilizing the piezoelectric effect, the system achieves the same mirror rotation functionality with significantly reduced operating parameters (voltage and power).
2Power
If a piezoelectric actuation system is used to reduce operating voltages and power consumption, then the actuation efficiency improves, but the system is not optimized for devices requiring tiltable structures to assume four different quasi-static positions
Solution Approach 1:
The patent divides the actuation system into four independent piezoelectric actuator pairs, with each pair responsible for controlling the mirror structure's position about one of the two rotation axes. This segmentation allows the system to achieve four different quasi-static positions while maintaining low power consumption through targeted, independent actuation of each position.
Solution Approach 2:
The patent designs a universal piezoelectric actuation system that can achieve multiple functions: rotation about the first rotation axis, rotation about the second rotation axis, and assuming four different quasi-static positions. The same piezoelectric material and actuation mechanism are used for all these functions, demonstrating multi-functionality without requiring separate systems for each capability.
3Adaptability or versatility
If the tiltable structure is elastically suspended to enable rotation about two axes, then the mirror can be directed to a projection area four times larger, but the mechanical structure becomes more complex
Solution Approach 1:
The patent merges the suspension function and the actuation function into a single integrated structure. The elastic suspension elements not only support the mirror structure but also serve as the mechanical pathway for piezoelectric actuation forces. This merging reduces the number of separate components and simplifies the overall mechanical structure while maintaining the capability to rotate about two axes and achieve four times larger projection area coverage.
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 proposed solution enables efficient and low-power tilting of the microelectromechanical mirror device about two axes, achieving high linearity, wide angles of rotation, and a compact structure, suitable for applications in projection apparatuses and microelectromechanical speaker devices.
Implementation Method 1
each driving arm carries, on a top surface thereof opposite to the cavity, a respective piezoelectric material region... biasing of the piezoelectric material regions causes the driving arms to rotate about a vertical axis
Implementation Method 2
the first and second elastic driving elements are rigid with respect to movements out of the horizontal plane, along a vertical axis orthogonal to the horizontal plane, and compliant to torsion
Data Source
AI summary
A microelectromechanical device includes a fixed structure having a frame defining a cavity, a tiltable structure elastically suspended above the cavity with main extension in a horizontal plane, a piezoelectrically driven actuation structure which can be biased to cause a desired rotation of the tiltable structure about a first and second rotation axes, and a supporting structure integral with the fixed structure and extending in the cavity starting from the frame. Lever elements are elastically coupled to the tiltable structure at a first end by elastic suspension elements and to the supporting structure at a second end by elastic connecting elements which define a lever rotation axis. The lever elements are elastically coupled to the actuation structure so that their biasing causes the desired rotation of the tiltable structure about the first and second rotation axes.