MEMS Light Deflector Protection Layers for Stable Vibration
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Solution Overview
Problem
Light deflectors manufactured using MEMS technology face issues with unstable vibration and durability due to rough side surfaces from incomplete protection layer removal or peeling during drive operation.
Innovation Solution
A light deflector design incorporating a pair of elastic support members with a silicon active layer, a piezoelectric section, and protection layers, where the second protection layer is partly removed and the first protection layer remains on the silicon active layer, ensuring stable vibration and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the protection layer is entirely removed, then the bar unit can be fully exposed for connection, but unstable vibration is induced by the roughed side surface
Solution Approach 1:
The patent applies local quality by selectively removing the second protection layer only from specific regions where electrical connections are needed, while retaining it on the bar unit's side surfaces. This localized approach provides protection exactly where required (preventing roughness-induced vibration) while enabling connections where exposed. The etching process targets specific areas to create different surface conditions in different locations of the same component.
Solution Approach 2:
The protection layer is segmented into two distinct layers (first and second protection layers) with different functions. The first protection layer provides baseline protection, while the second protection layer is selectively removed in specific segments to allow connections. This segmentation allows simultaneous protection and exposure functions within the same structural element.
2Reliability
If the protection layer remains unremoved, then the bar unit is protected, but the protection layer might peel off during drive operation
Solution Approach 1:
The patent extracts the second protection layer from specific regions where it would create adhesion problems during drive operation. By removing this layer only where necessary for connections and leaving it intact in other areas, the solution prevents peeling at critical interfaces while maintaining protection where needed. The selective extraction resolves the conflict between protection and adhesion stability.
Solution Approach 2:
The patent changes the physical state and presence of the protection layer through controlled etching parameters. By adjusting etching conditions to remove only the second layer in specific areas while preserving the first layer and the second layer in other areas, the solution creates optimal adhesion characteristics in different regions. This parameter control allows the structure to resist peeling during dynamic operation.
3Extent of automation
If piezoelectric sections and electrodes are added to the bar unit, then drive functionality is achieved, but layer separation and peeling occur during operation
Solution Approach 1:
The patent applies local quality by strategically positioning and selectively removing the second protection layer only in regions where electrical connections and piezoelectric sections are located. This creates locally optimized conditions: exposed surfaces for electrical contact where needed, and protected surfaces for mechanical strength where needed. The localized etching prevents layer separation at the interfaces between piezoelectric sections and electrodes by maintaining appropriate protection in those critical zones.
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 provides a light deflector with stable vibration and improved durability by preventing layer separation and side-surface roughness, enhancing the reliability of the device.
Implementation Method 1
a electrostrictive elements (piezoelectric force), thereby to perform two-dimensional optical scanning
Implementation Method 2
a movable unit having a reflecting surface to reflect light
Data Source
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AI summary
A light deflector (10) includes a movable unit (11) having a reflecting surface (5) to reflect light; a support (13 and 15) to support the movable unit (11); and a bar unit (111a, 111b, 112a, and 112b) connecting the movable unit (11) with the support (13 and 15). The bar unit (111a, 111b, 112a, and 112b) includes a pair of elastic support members (111a and 111b) to movably support the movable unit (11), and a pair of drive bars (112a and 112b) each including a silicon active layer (163), a piezoelectric section (202), a first protection layer (164), and a second protection layer (168) in the recited order. The pair of elastic support members (111a and 111b) each includes the first protection layer (164).