Hybrid MEMS Mirror-Gimbal Scanning for Low Power and Durability
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Solution Overview
Problem
MEMS scanning devices face a tradeoff between energy efficiency and durability due to the need for flexible hinges, which are prone to breaking under mechanical stress, and stiff mechanical bearings that require more energy to drive.
Innovation Solution
A hybrid scanning device design combining MEMS hinges and mechanical bearings, where MEMS mirrors oscillate about flexible hinges at resonant frequencies for low power consumption and the gimbal rotates in low-friction mechanical bearings for robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If flexible MEMS hinges are used to allow mirror oscillation, then the device can operate at resonant frequencies for low power consumption, but the hinges are prone to breaking under mechanical stress
Solution Approach 1:
The scanning device is divided into two functional segments: the mirror assembly with flexible MEMS hinges for high-frequency oscillation, and the gimbal with rigid mechanical bearings for low-frequency rotation. This segmentation allows each component to use the most appropriate support mechanism for its specific operational requirements, resolving the contradiction between flexibility and durability.
Solution Approach 2:
The patent merges two different support mechanisms (MEMS hinges and mechanical bearings) into a hybrid system. The mirror assembly combines flexible hinges for resonant oscillation with a rigid gimbal structure for mechanical support, achieving both low power consumption and high reliability by allowing each subsystem to operate in its optimal regime.
2Reliability
If stiff mechanical bearings are used to support the gimbal, then the structure is more durable, but more energy is required to drive the rotation
Solution Approach 1:
The system uses dynamic operation at resonant frequencies for the mirror oscillation, which minimizes the energy required to drive the flexible hinges. The gimbal rotates at lower frequencies where mechanical bearings are more efficient, creating a dynamically optimized hybrid system that reduces overall energy consumption while maintaining structural robustness.
Solution Approach 2:
The patent changes the operational parameters of different components: the mirror assembly operates at high resonant frequencies with flexible hinges, while the gimbal operates at lower frequencies with mechanical bearings. This parameter differentiation allows each subsystem to minimize its energy consumption in its optimal operating regime.
3Duration of action of stationary object
If the gimbal rotates at low frequencies, then the mechanical bearings experience less wear, but the mirror oscillation frequency must be much higher
Solution Approach 1:
The scanning device segments the rotational motion into two distinct frequency domains: low-frequency gimbal rotation supported by mechanical bearings for durability, and high-frequency mirror oscillation supported by flexible MEMS hinges for efficiency. This frequency segmentation resolves the contradiction between bearing lifespan and oscillation speed.
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 hybrid design achieves lower energy consumption and increased durability by allowing mirrors to oscillate at desired frequencies with high quality factor and gimbal rotation with minimal energy input, enhancing versatility and robustness.
Implementation Method 1
an electromagnetic drive, which includes a stator assembly, which is fixed to the base and includes at least one core containing an air gap and one or more coils including conductive wire wound on the at least one core so as to cause the at least one core to generate a magnetic field in the air gap in response to an electrical current flowing in the conductive wire. At least one rotor includes one or more permanent magnets, which are fixed to the shaft of the gimbal and which are positioned in the air gap so as to rotate in response to the magnetic field.
Implementation Method 2
Typically, the first frequency is a resonant frequency of rotation of the at least one mirror within the support.
Data Source
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AI summary
A scanning device (20) includes a base (44) containing one or more rotational bearings (32) disposed along a gimbal axis. A gimbal (30) includes a shaft (70) that fits into the rotational bearings so that the gimbal rotates about the gimbal axis relative to the base. A mirror assembly (60) includes a semiconductor substrate, which has been etched and coated to define a support (26), which is fixed to the gimbal, at least one mirror (24), contained within the support, and a connecting member (28) connecting the at least one mirror to the support and defining at least one mirror axis, about which the at least one mirror rotates relative to the support.