Movable Comb Electrode Rib Structure for Stable Finger Spacing
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Solution Overview
Problem
The reliability of optical devices with movable comb electrodes and fixed comb electrodes is compromised due to distortion during movement, leading to fluctuations in the interval between comb fingers, which affects their performance as driving or monitoring electrodes.
Innovation Solution
Incorporating an electrode support portion with a rib portion that is thicker than the movable comb fingers, which supports the movable comb electrode, preventing distortion and maintaining a consistent interval between comb fingers, thereby enhancing the reliability of the optical device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable comb electrode and fixed comb electrode are merely provided without additional support structure, then the device complexity is reduced, but the movable comb electrode becomes distorted during movement, causing fluctuation in the interval between comb fingers and deteriorating device reliability
Solution Approach 1:
The electrode support portion is designed with non-uniform thickness, featuring a thicker rib portion (second thickness) at the support location and a thinner comb finger portion (first thickness). This local quality variation provides enhanced structural support exactly where needed to prevent distortion of the movable comb electrode during movement, while maintaining simplicity in other areas.
Solution Approach 2:
The electrode support portion is segmented into functionally distinct regions: the rib portion that provides structural support and the comb finger portion that participates in electrostatic actuation. This segmentation allows each region to be optimized for its specific function, with the rib portion preventing distortion and the comb finger portion enabling movement.
2Stability of the object's composition
If the thickness of the electrode support portion is increased to prevent distortion, then the structural stability is improved, but the device complexity increases
Solution Approach 1:
The electrode support portion implements local quality by having different thicknesses in different regions. The rib portion has a greater thickness (second thickness) to provide the necessary structural stability and prevent distortion during movement, while the comb finger portion maintains a smaller thickness (first thickness) to allow for proper electrostatic actuation and reduce unnecessary mass.
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 solution effectively suppresses distortion of the electrode support portion and maintains a consistent interval between movable and fixed comb fingers, ensuring reliable operation as both driving and monitoring electrodes, improving the overall reliability of the optical device.
Implementation Method 1
a voltage is applied to between the movable comb electrode and the fixed comb electrode to move the movable unit along a movement direction
Implementation Method 2
electrostatic capacitance between the movable comb electrode and the fixed comb electrode is detected to understand a position of the movable unit that is moving along the movement direction
Data Source
AI summary
An optical device includes a base that includes a main surface, a movable unit that includes an optical function unit, an elastic support unit that supports the movable unit so that the movable unit is movable along a predetermined direction perpendicular to the main surface, a fixed comb electrode that includes a plurality of fixed comb fingers, and a movable comb electrode that includes a plurality of movable comb fingers which are disposed alternately with the plurality of fixed comb fingers. At least one of the movable unit and the elastic support unit includes an electrode support portion that supports the movable comb electrode. The electrode support portion includes a rib portion that is formed so that the thickness of the electrode support portion in the predetermined direction is larger than the thickness of the movable comb fingers in the predetermined direction.