Cascaded Electrostatic Actuator for Extended Travel Range
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Solution Overview
Problem
Existing gap-closing MEMS actuators have limited travel range due to the inverse square law of electrostatic attraction, making them less versatile compared to comb actuators, which lack the actuation force of gap-closing actuators.
Innovation Solution
A cascaded electrostatic actuator design is implemented, where multiple parallel plates are stacked with alternating fingers or electrodes, allowing for increased travel by closing multiple gaps simultaneously under controlled voltage pulses, enhancing both travel range and actuation force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If gap-closing actuators are used to achieve high actuation force, then force is improved, but travel range deteriorates
Solution Approach 1:
The actuator is divided into multiple independent gap-closing units stacked in series, each capable of closing its own gap independently. This segmentation allows the system to achieve both high force (from individual gap closure) and extended travel (from cumulative closure of multiple gaps), resolving the contradiction between force and travel range.
Solution Approach 2:
The invention transitions from a single-plane actuation mechanism to a three-dimensional stacked architecture. By arranging multiple gap-closing units vertically in series along the travel direction, the system achieves extended travel range through cumulative displacement while maintaining high actuation force from each individual gap closure event.
2Length of moving object
If comb actuators are used to achieve large travel range, then travel range is improved, but actuation force deteriorates
Solution Approach 1:
The comb actuator structure is segmented into multiple discrete gap-closing units, each contributing to the overall travel range while maintaining the high force characteristics of gap-closing mechanisms. This segmentation allows the system to achieve large cumulative travel without sacrificing actuation force, as each segment independently closes its gap with high force.
Solution Approach 2:
The invention merges the advantages of both gap-closing and comb actuator architectures by combining the high force mechanism of gap-closing actuators with the extended travel capability of comb actuators. The resulting hybrid structure achieves both large travel range and high actuation force simultaneously.
3Length of moving object
If multiple gaps are closed simultaneously to increase travel, then travel range is improved, but control complexity increases
Solution Approach 1:
The control system dynamically selects which gaps to close based on the desired travel distance, rather than closing all gaps simultaneously. This dynamic control approach allows the system to achieve variable travel ranges by activating only the necessary number of gap-closing units, reducing control complexity while maintaining extended travel capability.
Solution Approach 2:
The actuator operates through periodic cycles of voltage application and release, where each cycle closes a specific subset of gaps. This periodic action pattern simplifies control by using repetitive voltage pulse sequences to achieve cumulative travel, rather than requiring complex simultaneous multi-gap control.
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 provides greater travel and force capabilities while maintaining controlled movement, suitable for applications like camera lenses and image stabilization, by leveraging the electrostatic attraction across multiple gaps, thus bridging the gap between the advantages of gap-closing and comb actuators.
Implementation Method 1
the electrostatic attractive force is inversely proportional to the square of the separation distance according to Coulomb's law. Thus as the gap separation is reduced towards zero, the electrostatic attractive force is markedly increased
Implementation Method 2
the electrostatic attractive force is inversely proportional to the square of the separation distance according to Coulomb's law
Data Source
AI summary
In one embodiment, a device is provided that includes: a plurality of actuators arranged into a plurality of rows and a plurality of columns; a plurality of row conductors corresponding to the plurality of rows; a plurality of column conductors corresponding to the plurality of columns; and a controller configured to select at least one of the actuators in a row by raising a voltage on the corresponding row conductor to couple each selected actuator to its corresponding column conductor.