MEMS Mirror Antistatic Structure for Drift Control
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Solution Overview
Problem
MEMS mirror devices face challenges with drift phenomena due to electrostatic forces, requiring effective methods to suppress drift and achieve low-voltage driving while maintaining high yield and cost reduction, especially in small-scale devices where inertial forces are minimal.
Innovation Solution
Incorporating an antistatic structure between the mirror and electrode substrates, along with a method of manufacturing that includes forming metal layers on both surfaces of the mirror and using a protective layer to prevent damage, allows for precise control of the mirror's pivot angle and reduces charge/discharge time constants, thereby minimizing drift and enhancing manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interelectrode distance is increased to reduce the risk of discharge, then the voltage difference required increases, but this leads to higher power consumption and reduced driving efficiency
Solution Approach 1:
The patent introduces an antistatic structure that changes the electrical parameters of the system by providing an additional charge discharge path. This structure includes conductive elements connected to ground that enable static charge dissipation, allowing the mirror device to operate at lower voltages without discharge risks, thus reducing power consumption while maintaining reliability
2Volume of moving object
If the mirror size is reduced to achieve miniaturization, then inertial forces become negligible, but electrostatic drift becomes more significant and harder to control
Solution Approach 1:
The patent introduces an antistatic structure as an intermediary element between the mirror and the driving electrodes. This structure includes conductive layers and charge dissipation paths that actively manage electrostatic charges, preventing drift while allowing the mirror to maintain its small size for miniaturization applications
3Ease of manufacture
If conventional manufacturing methods are used without protective layers, then the manufacturing process is simpler, but the mirror substrate is vulnerable to damage and yield is reduced
Solution Approach 1:
The patent implements a protective layer structure that is formed beforehand during the manufacturing process. This protective layer includes sacrificial layers and support structures that prevent damage to the mirror substrate during fabrication and assembly, thereby increasing manufacturing yield without significantly complicating the manufacturing process
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 drift in MEMS mirror devices, allows for controlled warp and increased pivot angles, and reduces power consumption by enabling low-voltage driving, resulting in more reliable and efficient optical switches.
Implementation Method 1
an antistatic structure which is arranged in a space between the mirror and the electrode substrate
Implementation Method 2
A positive voltage is applied to the driving electrodes 8003-1 to 8003-4 to generate an asymmetrical potential difference between the driving electrodes 8003-1 to 8003-4. An electrostatic force attracts the mirror 8103 and causes it to pivot in an arbitrary direction.
Data Source
AI summary
A mirror device includes a mirror (153) which is supported to be pivotable with respect to a mirror substrate (151), a driving electrode (103-1-103-4) which is formed on an electrode substrate (101) facing the mirror substrate, and an antistatic structure (106) which is arranged in a space between the mirror and the electrode substrate. This structure can fix the potential of the lower surface of the mirror and suppress drift of the mirror by applying a second potential to the antistatic structure.