MEMS Optical Deflector Rigidity Tuning Without Torsion Bar Damage
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Solution Overview
Problem
The durability of torsion bars in MEMS optical deflectors is compromised due to piezoelectric film peeling or wiring breakage, and stress concentration occurs at intermediate points, affecting resonance frequency adjustment.
Innovation Solution
A MEMS optical deflector design with rigidity changing piezoelectric elements positioned in specific support regions, ensuring appropriate dimensions to adjust resonance frequency without durability issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a long piezoelectric film or wiring is formed on the torsion bar to adjust resonance frequency, then the resonance frequency can be changed, but the piezoelectric film peels off or the wiring breaks due to the thin and high-frequency reciprocating nature of the torsion bar
Solution Approach 1:
The patent transitions from forming piezoelectric films or wiring along the longitudinal direction of the torsion bar to forming them in the width direction at the center of the torsion bar. This dimensional change reduces the length of the piezoelectric film and wiring, minimizing their exposure to high-frequency reciprocation stresses and preventing peeling or breakage while maintaining resonance frequency adjustment capability.
2Adaptability or versatility
If a piezoelectric element is provided at an intermediate point between support point and mirror portion to adjust resonance frequency, then the resonance frequency can be changed, but stress concentration occurs at the intermediate point and durability is lowered
Solution Approach 1:
The patent applies local quality by concentrating the piezoelectric element at the center of the torsion bar in the width direction rather than distributing it along the length. This localized placement at the neutral axis minimizes stress concentration while still enabling effective resonance frequency adjustment through targeted rigidity modification.
3Area of stationary object
If multiple MEMS optical deflectors are used to scan images, then scanning coverage is improved, but seams appear in scanned images due to resonance frequency differences between deflectors
Solution Approach 1:
The patent employs parameter changes by adjusting the resonance frequency of multiple MEMS optical deflectors to a common value through controlled modification of torsion bar rigidity. By changing the rigidity parameter of each deflector's torsion bar, the resonance frequencies are standardized, eliminating seams in scanned images while preserving expanded scanning coverage.
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 design allows for smooth adjustment of resonance frequency while maintaining torsion bar durability, improving image quality by aligning resonance frequencies across multiple deflectors and reducing seams in scanned images.
Implementation Method 1
a piezoelectric film is formed in the torsion bar in the entire extending direction thereof, and the torsion bar is expanded and contracted in the extending direction by applying a voltage to the piezoelectric film to change a rigidity of the torsion bar
Implementation Method 2
the torsion bars are twisted and vibrated around the rotation axis, and the mirror portion is reciprocated around the rotation axis at a resonance frequency
Data Source
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AI summary
An optical scanning device of the present invention includes a mirror portion, a torsion bar (112a) extending along a resonance axis, an annular-shaped body coupled to the torsion bar (112a) from both sides of the resonance axis to rotate the mirror portion, and an intersection portion piezoelectric element (45) and/or coupling portion piezoelectric elements (46a, 46b) formed in a rigidity adjustment region including an intersection portion of the torsion bar (112a) and the annular-shaped body to change a rigidity of the rigidity adjustment region when a voltage is applied.