Folded Ribbon Electrostatic Actuator for High Force and Long Stroke
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Solution Overview
Problem
Conventional electrostatic actuators composed of ribbon-shaped electrode films face challenges in generating a large electrostatic force due to their paper spring-shaped structure, which limits their ability to produce a significant stroke while maintaining a large force.
Innovation Solution
The electrostatic actuator design involves folding and laminating ribbon-shaped first and second electrode films, with end and intermediate electrodes, and employing specific folding patterns to enhance the electrostatic force generation, allowing for a multilayer structure that increases the stroke amount and improves the spring characteristic by varying the spring constant between driving and overload regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the area of each electrode is increased to obtain a large generation force, then the electrostatic force is improved, but the device complexity and structural compactness deteriorate
Solution Approach 1:
The patent implements a nested structure where multiple electrode pairs are arranged in series along the length of the ribbon-shaped electrode films. The first and second electrode films are folded back and forth to create multiple overlapping electrode sections (first through fourth electrode sections) that are nested within each other along the longitudinal direction. This nesting arrangement allows multiple electrostatic force-generating elements to be packed into a compact linear structure, achieving large total electrostatic force without increasing the cross-sectional area or overall device footprint.
Solution Approach 2:
The patent transitions from a two-dimensional electrode arrangement to a three-dimensional folded structure. The ribbon-shaped electrode films are folded in the longitudinal direction to create multiple electrode pairs stacked along the length of the actuator. This dimensional transformation allows the electrostatic force to be generated across multiple planes and levels, effectively multiplying the force output while maintaining a compact linear form factor suitable for integration into limited spaces.
2Length of moving object
If a paper spring-shaped structure is used to achieve long stroke, then the stroke is improved, but the electrostatic force generation deteriorates
Solution Approach 1:
The patent divides the continuous ribbon-shaped electrode films into multiple discrete electrode sections (first, second, third, and fourth electrode sections) separated by hinge sections. Each electrode section can independently interact with its counter-electrode to generate electrostatic force. The hinge sections act as flexible joints that allow each segment to move relative to others, enabling the entire structure to achieve large stroke through cumulative displacement of multiple segments while each segment maintains effective electrostatic coupling.
Solution Approach 2:
The multiple electrode sections are nested along the longitudinal direction of the ribbon films, with each section positioned to overlap with its counter-electrode section. This nested arrangement allows the actuator to achieve long stroke by extending the series of nested electrode pairs along the length of the device, rather than relying on a single large electrode pair. The nesting maintains compact cross-sectional dimensions while providing extended stroke capability through the longitudinal arrangement of multiple force-generating elements.
3Force
If the electrode film is made thick to increase force, then the electrostatic force is improved, but the flexibility and stroke capability deteriorate
Solution Approach 1:
The patent applies different structural properties to different regions of the electrode film. The electrode sections are made with sufficient thickness to generate adequate electrostatic force, while the hinge sections connecting these electrode sections are made thinner and more flexible. This local differentiation allows the electrode sections to maintain structural integrity and force-generating capability, while the thinner hinge sections provide the necessary flexibility for large-range motion and bending, enabling the overall structure to achieve both force and stroke requirements.
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 enables the generation of a large electrostatic force while maintaining a long stroke, achieving an ideal spring characteristic with a significant increase in spring constant in the overload region, allowing for both contraction and extension with varying voltage polarities.
Implementation Method 1
an electrostatic actuator using a generation force based on an electrostatic attractive force to be generated between electrodes as a driving force
Data Source
AI summary
The present invention is directed to providing an electrostatic actuator that can generate a large electrostatic force even if composed of a ribbon-shaped electrode film.In an electrostatic actuator 10, 20 including a ribbon-shaped first electrode film 11 and a ribbon-shaped second electrode film 12, a plurality of first electrodes 1 formed of the first electrode film 11 and a plurality of second electrodes 2 formed of the second electrode film 12 are folded and laminated between one end 13 and the other end 14 of the electrostatic actuator 10, 20, and the plurality of first electrodes 1 include a pair of end electrodes 1a that are adjacent to each other in a direction in which the first electrode film 11 extends in a ribbon shape and are respectively positioned at the one end 13 and the other end 14 when laminated and at least one intermediate electrode 1b that is positioned between the end electrodes 1a when laminated.