Gimbaled MEMS Mirror Actuation via Segmented Electrostatic and Electromagnetic Drivers
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Solution Overview
Problem
Current micro-mirror devices face challenges in achieving linear and repeatable scans with low power consumption, high resolution, and increased scan angles due to mechanical coupling and interference between two degrees of freedom, particularly in gimbaled micro-mirror scanners using electrostatic and electromagnetic actuators.
Innovation Solution
A micro-electro-mechanical system (MEMS) device employing a symmetric internal electrostatic actuator and a symmetric external electromagnetic actuator, with the electromagnetic actuator providing negligible residual force on the second degree of freedom and the electrostatic actuator using fringing fields for rotational movement, both fabricated using a 4-masks Silicon-On-Insulator process to eliminate mechanical coupling and optimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrostatic actuators are used to actuate micro-mirrors in two DOF, then the device can achieve two-dimensional scanning, but mechanical coupling between the two DOF occurs which affects scan linearity and image sharpness
Solution Approach 1:
The patent divides the actuation system into two separate actuators: an electrostatic actuator for one DOF and an electromagnetic actuator for the other DOF. This segmentation eliminates the mechanical coupling that occurs when a single electrostatic actuator attempts to control both DOF, thereby maintaining scan linearity while achieving two-dimensional scanning capability.
Solution Approach 2:
The patent introduces an electromagnetic actuator as an intermediary element to handle one of the two DOF. This intermediary actuator works in conjunction with the electrostatic actuator to provide independent control over each degree of freedom, preventing the mechanical coupling that would otherwise degrade scan linearity.
2Device complexity
If a single actuator is used to excite motion in both scanning axes, then device complexity is reduced, but mechanical coupling occurs which reduces operation quality and efficiency
Solution Approach 1:
Instead of using a single actuator for both scanning axes, the patent segments the actuation function into two separate actuators: an electrostatic actuator and an electromagnetic actuator. Each actuator is responsible for one DOF, which eliminates mechanical coupling and improves operation quality while maintaining reasonable device complexity.
Solution Approach 2:
The patent employs two different types of actuators (electrostatic and electromagnetic) to achieve multi-functionality in a single scanning system. This allows each actuator to be optimized for its specific DOF while working together to provide complete two-dimensional scanning capability.
3Volume of moving object
If electrostatic actuators are used for two DOF actuation, then the structure can be compact, but power consumption increases and scan linearity deteriorates
Solution Approach 1:
The patent segments the actuation load by using an electromagnetic actuator for one DOF and an electrostatic actuator for the other DOF. This segmentation allows each actuator to operate more efficiently in its optimized DOF, reducing overall power consumption while maintaining a compact device size.
Solution Approach 2:
The patent changes the actuation parameter by switching from purely electrostatic actuation to a hybrid electromagnetic-electrostatic approach. This parameter change enables more efficient energy utilization for two DOF actuation while eliminating the mechanical coupling that degrades scan linearity.
4Measurement precision
If the scan frequency is increased to improve resolution, then image quality improves, but the mechanical coupling and interference between DOF become more pronounced
Solution Approach 1:
By segmenting the actuation into two independent actuators, the patent eliminates mechanical coupling that would otherwise become more pronounced at high scan frequencies. This allows the system to achieve high display resolution through increased scan frequency without compromising scan linearity.
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 solution enables high-quality, linear, and repeatable scans across both axes with reduced power consumption and increased scan angles, eliminating mechanical coupling and improving feedback sensor resolution, thus enhancing the performance of micro-mirror devices.
Implementation Method 1
Electromagnetic, where alternating current in a magnetic field induces a magnetic force to move the mirror
Implementation Method 2
Electrostatic, where capacitance change induces an electrostatic force to move the mirror about an axis
Data Source
AI summary
A Micro-Electro-Mechanical Systems (MEMS) device for actuating a gimbaled element, the device comprising a symmetric electromagnetic actuator for actuating one degree of freedom (DOF) and a symmetric electrostatic actuator for actuating the second DOF.