2D Micromechanical Actuator With Multiple-Plane Comb Electrodes
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Solution Overview
Problem
Conventional electrostatic driven two-dimensional micro-electro-mechanical actuators, such as those with parallel plate electrodes, struggle to achieve large optical scanning angles due to limitations in actuation force, while comb-drive actuators require more space and higher manufacturing precision.
Innovation Solution
A two-dimensional micro-electro-mechanical actuator design incorporating both in-plane and vertical comb electrodes, with dual-side vertical comb electrodes, to enhance motion control and increase actuation force, allowing for larger optical scanning angles and improved manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If parallel plate electrodes are used, then the structure is simple, but the optical scanning angle is limited due to insufficient actuation force
Solution Approach 1:
The patent transitions from conventional parallel plate electrodes to comb-drive electrodes that extend in the vertical dimension, creating interdigitated fingers that provide larger lateral actuation force while maintaining a compact footprint. This dimensional change enables the mirror to achieve large scanning angles without requiring complex multi-layer staggered structures.
2Adaptability or versatility
If vertical comb actuators in staggered three-layer architecture are used, then bi-directional rotation is enabled, but the device occupies twice the space and requires higher manufacturing precision
Solution Approach 1:
The patent employs in-plane comb electrodes arranged in a planar configuration rather than vertical staggered layers, enabling bi-directional rotation while maintaining a compact footprint. The comb fingers are oriented to provide actuation forces in multiple directions within the same plane, eliminating the need for multi-layer vertical structures.
Solution Approach 2:
The in-plane comb electrode structure serves multiple functions simultaneously: it provides bidirectional actuation, maintains compact size, and simplifies manufacturing. The same planar electrode arrangement enables rotation about both principal axes without requiring separate vertical comb structures for each direction.
3Adaptability or versatility
If vertical comb electrodes in staggered structure are used, then bi-directional rotation is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent adopts in-plane comb electrodes that are fabricated within the same planar layer rather than requiring vertical alignment of staggered layers. This planar configuration significantly reduces manufacturing precision requirements by eliminating the need for precise vertical stacking and alignment of multiple layers, while still achieving bidirectional rotation capability.
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 actuator achieves enhanced motion control and larger optical scanning angles with reduced manufacturing complexity, enabling applications like scanning laser projection displays and confocal microscopes with smaller product footprints.
Implementation Method 1
the electrostatic attraction force is inverse proportional to the distance between the mirror and the underneath driving electrode
Data Source
AI summary
A micro-electro-mechanical actuator consists of a first semiconductor layer comprising a movable element with comb electrodes, a support element with inner and outer comb electrodes and a stationary element with comb electrodes, an electrical insulation layer, and a second semiconductor layer with a cavity to allow out-of-plane rotation of the movable and support elements. The movable element is mounted to the support element by a first pair of torsional hinges whereas the support element is mounted to the stationary element by a second pair of torsional hinges such that the actuator is in gimbaled structure. Inner comb electrodes of the support element interdigitate with comb electrodes of the movable element, and outer comb electrodes of the support element interdigitate with comb electrodes of the stationary element in the same plane defined by the first semiconductor layer to form in-plane comb-drive actuators. The in-plane comb-drive actuator may be controlled to generate two-dimensional oscillation of the movable element about the two axes defined by the torsional hinges. The second semiconductor layer may further comprise comb electrodes which interdigitate vertically with outer comb electrodes of support element to form vertical comb-drive actuators. Combing the in-plane and the vertical comb-drive actuators, the movable element is controllable to perform two-dimensional raster scan motion.