Comb Electrode Support Rib for Optical Positioning Reliability
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Solution Overview
Problem
The movable comb electrode and fixed comb electrode in optical devices can distort during movement, leading to reliability issues due to inconsistent intervals between comb fingers, affecting both driving and monitoring functions.
Innovation Solution
The optical device incorporates a rib portion in the electrode support portion, with a thickness greater than the movable comb fingers, supported by a substrate structure including a support layer, device layer, and intermediate layer, to suppress distortion and maintain consistent intervals between comb fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the movable comb electrode is provided with thin comb fingers to reduce mass and improve response speed, then the response speed improves, but the structural strength decreases leading to distortion during movement
Solution Approach 1:
The patent increases the thickness of the electrode support portion in the vertical direction (perpendicular to the main surface) to provide structural strength, while keeping the comb fingers thin for fast response. This dimensional differentiation allows the support structure to be strong without making the moving comb fingers bulky, thus resolving the contradiction between response speed and structural strength.
2Manufacturing precision
If the electrode support portion has uniform thickness to simplify manufacturing, then manufacturing precision improves, but distortion occurs during movement due to insufficient support stiffness
Solution Approach 1:
The patent applies different thickness values to different portions of the electrode support structure. The electrode support portion has a greater thickness than the comb fingers, creating local structural reinforcement. This local quality differentiation provides the necessary stiffness to prevent distortion during movement while maintaining manufacturing feasibility through defined geometric parameters.
3Use of energy by moving object
If the movable comb electrode is made lightweight to improve driving efficiency, then energy consumption decreases, but the electrode becomes more susceptible to distortion under electrostatic forces
Solution Approach 1:
The patent optimizes the mass-thickness ratio by making the comb fingers thin (reducing mass for energy efficiency) while making the support portion thick (providing stiffness for distortion resistance). This dimensional differentiation allows the structure to be lightweight yet rigid, resolving the contradiction between energy efficiency and distortion resistance.
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 enhances the reliability of the optical device by ensuring integral movement of the movable comb electrode with the movable unit, maintaining consistent electrostatic forces and capacitance detection over the movable range, thus improving both driving efficiency and monitoring accuracy.
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
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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.