Two-axis MEMS Mirror with Separated Piezoelectric Drives
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Solution Overview
Problem
MEMS mirror systems used in LiDAR applications face challenges due to temperature-induced changes in resonance frequencies, requiring complex frequency tuning components and electronics to maintain scanning behavior, and manufacturing imperfections lead to complicated actuation and control of oscillation modes.
Innovation Solution
A micromechanical reflector system with a reflector body suspended by a plurality of suspenders, each comprising an outer, middle, and inner section, with piezoelectric actuators on the outer and inner sections, allowing for orthogonal rotation axes and reduced complexity in actuation, and using springs to connect the suspenders to the reflector body for efficient oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a gimbal-based system is used to achieve two-axis tilting oscillation, then the scanning capability across a solid angle is improved, but the device complexity increases due to significantly different resonance frequencies requiring complex frequency tuning components and electronics
Solution Approach 1:
The suspender is divided into three distinct sections (outer section, middle section, inner section) with different functions. The outer section provides structural support and attachment to the support structure, the middle section provides flexible suspension while maintaining geometric relationships, and the inner section contains the piezoelectric actuator and connects to the reflector body. This segmentation allows each section to be optimized independently for its specific function.
Solution Approach 2:
The middle section of the suspender acts as an intermediary element between the outer section and the inner section. It maintains the geometric relationships and flexible connections while isolating the actuator in the inner section from the structural support in the outer section, enabling independent optimization of structural and actuation functions.
2Ease of operation
If the resonance frequencies are tuned to be significantly different in a gimbal-based system, then the oscillation modes are well-separated, but the system becomes more sensitive to temperature changes requiring complex adaptive tuning
Solution Approach 1:
The resonant frequencies of the oscillation modes are made closely matched through the specific geometric configuration and material selection of the suspender sections. This parameter optimization reduces the frequency difference between modes, making the system less sensitive to temperature-induced frequency shifts and eliminating the need for complex adaptive tuning.
3Measurement precision
If four suspenders are used to achieve orthogonal rotation axes, then the scanning precision is improved, but the manufacturing complexity increases due to the need for precise geometric relationships between all suspenders
Solution Approach 1:
The suspender employs asymmetric section configurations where the outer, middle, and inner sections have different geometric properties optimized for their specific functions. This allows the four suspenders to be designed with standardized asymmetric patterns that can be manufactured with consistent precision while achieving the required orthogonal rotation capabilities.
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 system achieves stable and precise oscillation with reduced dynamic deformations and minimizes the effect of environmental changes on resonance frequencies, eliminating the need for complex adaptive tuning elements and circuitry, thereby enhancing scanning performance in LiDAR applications.
Implementation Method 1
a first piezoelectric actuator is located on the outer section and a second piezoelectric actuator is located on the inner section
Data Source
AI summary
The invention relates to microelectromechanical systems (MEMS), and specifically to a mirror system, for example to be used in LiDAR (Light Detection and Ranging). The MEMS mirror system of the invention uses four suspenders, each of which is connected to the reflector body at two separate connection points which can be independently displaced by piezoelectric actuators. By actuating adjacent and opposite pairs of piezoelectric actuators, the reflector body can be driven to oscillated about two orthogonal axes.