Electrostatic MEMS Micromirror Comb Frame for Stable Wide Rotation
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Solution Overview
Problem
Existing electrostatic MEMS micromirrors face challenges in expanding the rotation angle range and stability due to factors such as residual stress, temperature changes, and external impacts, which can cause buckling, fracture, and failure.
Innovation Solution
The design incorporates a comb frame located on both sides of the rotating axis, supporting the micromirror with multiple points, and includes reinforcement rods to enhance stability and driving force, with symmetrical comb structures and optimized slot configurations to increase the rotation angle range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the movable comb is extended near the rotating axis to increase driving force, then the rotation angle range is improved, but the device becomes more susceptible to external impact and residual stress
Solution Approach 1:
The movable comb is designed with asymmetric geometry where the distance from the fixed end to the rotating axis is greater than the distance from the free end to the rotating axis. This asymmetric configuration optimizes the moment arm for electrostatic force generation, maximizing driving torque while maintaining structural integrity. The asymmetric design allows the comb to achieve greater rotation angle range without proportionally increasing vulnerability to external impacts and residual stress.
2Stability of the object's composition
If the comb frame is positioned on both sides of the rotating axis to increase moment of inertia, then stability is improved, but the device complexity increases
Solution Approach 1:
The comb frame is designed to serve multiple functions simultaneously: it provides mechanical support for the micromirror, acts as a structural element to increase moment of inertia for stability, serves as an anchor for the movable comb, and functions as part of the electrostatic actuation system. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving improved stability.
3Reliability
If reinforcement rods are added to enhance stability and suppress high-order mode interference, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The reinforcement rods are integrated with the comb frame structure, merging the reinforcement function into the existing structural framework. This integration allows the reinforcement elements to be manufactured as a unified structure rather than separate components requiring additional assembly steps. The combined structure maintains stability enhancement while simplifying the manufacturing process by reducing the number of discrete parts and assembly operations.
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 improved design increases the moment of inertia and driving force, enhancing the stability and rotation angle range of the micromirror, while suppressing high-order mode interference.
Implementation Method 1
The stationary comb structure is configured to generate electrostatic force with the movable comb structure
Implementation Method 2
a moment of inertia of an area of the electrostatic MEMS micromirror is increased, thereby improving stability of a device
Data Source
AI summary
An electrostatic MEMS micromirror is provided, and may be used in a device such as a mobile phone, a microphone, a camera, a radar, or an optical switch. The electrostatic MEMS micromirror includes a support beam, a micromirror, and a drive component. The drive component includes a comb frame and a drive comb located in the comb frame. The support beam and the micromirror are mechanically coupled using the comb frame. Two sides of the comb frame that are mechanically coupled to the micromirror are separately located on two sides of a rotating axis determined by the support beam. The drive comb includes at least one comb pair. The comb pair includes a movable comb structure and a stationary comb structure. The movable comb structure includes a plurality of movable combs. One end of the movable comb is fastened to the comb frame.