Piezoelectric MEMS Mirror Electrode Segmentation
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Solution Overview
Problem
Conventional piezoelectric MEMS scanners require high voltage (about 40V) to achieve sufficient displacement angles and suffer from reduced driving force when used in resonance driving due to the need for a cantilever as a sensor, limiting their displacement efficiency.
Innovation Solution
The electrode arrangement is optimized to align with stress distributions in the piezoelectric body, allowing efficient driving and increased mirror inclination angles, even when part of the electrodes are used for sensing, by applying drive voltages with opposite phases to corresponding electrode sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional piezoelectric MEMS scanner structure is used, then high torque density is achieved, but high voltage (about 40V) is required to obtain sufficient displacement angle
Solution Approach 1:
The piezoelectric body is divided into multiple sections with electrodes arranged correspondingly to stress distribution. This segmentation allows different regions of the piezoelectric body to be activated efficiently, converting piezoelectric torque into tilting displacement more effectively and reducing the voltage requirement from 40V to a lower level while maintaining sufficient displacement angle.
Solution Approach 2:
Electrodes are arranged in specific patterns (first and second electrode sections) that correspond to the local stress distribution in the piezoelectric body. This local quality optimization ensures that electrical energy is converted to mechanical displacement with maximum efficiency in each region, improving overall displacement efficiency and reducing voltage requirements.
2Speed
If resonance driving is used with conventional structure, then high displacement angle is obtained, but driving force is significantly reduced to about half due to using one cantilever as sensor
Solution Approach 1:
The electrode arrangement enables the piezoelectric body to serve multiple functions simultaneously. The segmented electrodes allow for efficient torque conversion while maintaining sufficient driving force for resonance operation, eliminating the need to sacrifice one cantilever as a sensor and thereby preserving full driving force.
Solution Approach 2:
The invention changes the structural parameters of the electrode arrangement to optimize the conversion of piezoelectric torque into tilting displacement. This parameter optimization improves displacement efficiency and maintains large displacement angles during resonance driving without significantly reducing driving force.
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 approach enhances displacement efficiency and maintains large displacement angles, enabling effective optical scanning with reduced voltage requirements and stable resonance driving.
Implementation Method 1
a piezoelectric body 66
Implementation Method 2
resonance driving
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
In a mirror drive device, a first actuator section and a second actuator section are arranged on both sides of a mirror supporting section that supports a mirror section so as to sandwich the mirror supporting section. The upper electrode of a first actuator section includes a first electrode section and a second electrode section, and an upper electrode of a second actuator section includes a third electrode section and a fourth electrode section. The arrangements of the electrode sections correspond to stress distribution of principal stresses in the piezoelectric body in resonant mode vibration, and in a piezoelectric body portion that corresponds to positions of the first electrode section and the third electrode section and a piezoelectric body portion that corresponds to positions of the second electrode section and the fourth electrode section, stresses in opposite directions to each other are generated.