MEMS Actuator Design for High Fill Factor and Minimal Lateral Displacement
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Solution Overview
Problem
Existing MEMS devices face challenges in achieving high area efficiency while maintaining large deflections, as they often experience lateral displacement during tilting motions, leading to light loss in optical applications and limited scan angles.
Innovation Solution
The MEMS design suspends a movable element over at least two column structures, which reduces lateral displacement during tilting, allowing for a more area-efficient configuration and minimizing light loss. This is achieved by connecting spring elements between the substrate and column structures, which support the movable element and enable precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If actuators are placed below the useful area to maintain long length, then area efficiency is improved, but lateral displacement occurs during tilting motion
Solution Approach 1:
The patent transitions from a single-plane actuator arrangement to a three-dimensional configuration by positioning actuators at different heights (first actuators below the useful area, second actuators above the useful area). This vertical dimensionality change enables the system to achieve both high fill factor and minimal lateral displacement by distributing actuation forces across multiple spatial dimensions.
Solution Approach 2:
The actuation system is segmented into multiple independent actuator groups: first actuators positioned below the useful area and second actuators positioned above it. This segmentation allows each actuator group to contribute differently to the tilting motion, with the combined effect achieving pure rotation without lateral displacement while maintaining high area efficiency.
2Length of moving object
If column height is increased to allow large mirror plate tilting, then tilt angle is improved, but light loss increases
Solution Approach 1:
Instead of increasing column height in the vertical dimension to achieve larger tilt angles, the patent uses a dual-plane actuator configuration that enables effective tilting through coordinated actuation of first and second actuators. This approach achieves the desired tilt angle without requiring excessive column height, thereby minimizing light loss while maintaining geometric feasibility.
3Adaptability or versatility
If actuators are arranged orthogonally along x- and y-axes, then two-axis tilt is achieved, but diagonal scan angle is limited to 70% of maximum
Solution Approach 1:
The patent adds a vertical dimension to the actuator arrangement by positioning second actuators above the useful area in addition to first actuators below it. This three-dimensional configuration enables independent control of tilting moments around both x and y axes, allowing the system to achieve full diagonal scan angles equal to the maximum axial scan angles, thereby eliminating the 70% limitation of orthogonal two-dimensional arrangements.
4Device complexity
If single column structure is used to support movable element, then device complexity is reduced, but lateral displacement occurs during tilting
Solution Approach 1:
While maintaining relatively simple column structures, the patent introduces a dual-plane actuator configuration that works in conjunction with the columns to eliminate lateral displacement. The first actuators below and second actuators above the useful area create balanced force distributions that prevent lateral movement, achieving this without significantly increasing column complexity.
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 design effectively reduces lateral displacement, enhances area efficiency, and minimizes light loss, enabling MEMS devices to achieve larger tilt angles and higher fill factors while maintaining precise control over the movable element.
Implementation Method 1
a first spring element connected between the substrate and a first column structure connected to the second main surface, and a second spring element connected between the substrate and a second column structure connected to the second main surface
Data Source
AI summary
A MEMS includes a substrate having an element movably suspended relative to the substrate, the element having a first main surface and an opposite second main surface. The MEMS includes a first spring element connected between the substrate and a first column structure connected to the second main surface, and includes a second spring element connected between the substrate and a second column structure connected to the second main surface.