MEMS Mirror Backside Skeleton for LiDAR Stiffness
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Solution Overview
Problem
Large aperture MEMS micro-mirrors in LiDAR systems face challenges with dynamic deformation and increased moment of inertia, leading to reduced image resolution and higher power requirements due to the need for stiffer springs and larger driving forces.
Innovation Solution
A semiconductor integrated circuit with a microelectromechanical system (MEMS) micro-mirror assembly featuring a gimbal and support structure with etched cells to reduce material and increase stiffness, coupled with multiple torsion springs and electrostatic comb drives to enhance rotational force and reduce dynamic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If large aperture MEMS micro-mirrors are used to increase detection range, then the moment of inertia increases, but dynamic deformation increases causing light spot divergence and reduced image resolution
Solution Approach 1:
The support structure is segmented into a matrix of cells with radial and circumferential ridges, creating a skeletal framework that provides structural support while minimizing mass. This segmentation allows the mirror to maintain large aperture for detection range while reducing dynamic deformation through the distributed rigid support framework.
2Area of moving object
If large aperture MEMS micro-mirrors are used to increase detection range, then the moment of inertia increases, but larger driving force is required increasing power consumption
Solution Approach 1:
The cellular support structure segments the mirror assembly, creating a lightweight rigid framework that reduces the overall moment of inertia. This segmentation enables large aperture mirrors to be driven with smaller forces, reducing power consumption while maintaining the required aperture for detection range.
Solution Approach 2:
The invention changes the structural parameters of the support framework by creating a cellular matrix with specific ridge configurations. This parameter optimization reduces the mass and moment of inertia of the mirror assembly, allowing for lower power consumption while maintaining large aperture for extended detection range.
3Measurement precision
If springs with higher stiffness are used to maintain resonant frequency for high resolution imaging, then image resolution improves, but driving force requirement increases markedly
Solution Approach 1:
The invention optimizes the structural parameters of the support framework through cellular matrix design with radial and circumferential ridges. This parameter optimization enables the system to achieve high resonant frequency for image resolution while reducing the moment of inertia, thereby lowering the driving force and power requirements compared to conventional solid support structures.
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 solution effectively reduces the moment of inertia and dynamic deformation of the micro-mirror, improving image resolution and reducing the power requirements for LiDAR systems while maintaining structural integrity.
Implementation Method 1
electrostatic comb drives to enhance rotational force
Implementation Method 2
at least two torsion springs coupled to diametrically opposed ends of the gimbal, wherein the torsion springs are configured to apply a rotational force that causes the gimbal to rotate at the resonant frequency
Implementation Method 3
the support structure being etched to form a matrix of cells such that at least 50% of support structure material forming the support structure is removed
Data Source
AI summary
A Light Detection and Ranging (LiDAR) module for a vehicle can include a semiconductor integrated circuit with a microelectromechanical system (MEMS) and a substrate, the MEMS comprising a micro-mirror assembly including a mirror and a gimbal structure. The gimbal can be configured concentrically around and coplanar with the mirror. When rotated, the gimbal drives the mirror to oscillate at or near a resonant frequency and is coupled to the mirror via mirror-gimbal connectors. A support structure can be coupled to a backside of the mirror and gimbal structures and can increase the stiffness of the mirror to help the mirror better resist dynamic deformation. To limit the added rotational moment of inertia, the support structure can be etched to form a matrix of cells (e.g., formed by a mesh of circumferential and radial ridges) such that up to approximately 90% of the support structure material forming the support structure is removed.