Optical Deflector Rib Structure for Energy Leakage Reduction
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Solution Overview
Problem
Prior art optical deflectors suffer from energy leakage and reduced quality factor Q due to the low rigidity of outer coupling portions, leading to increased drive voltages required for desired deflection angles.
Innovation Solution
The optical deflector design incorporates a circumferential rib on the inner frame and branch ribs on the outer coupling portions to enhance the rigidity of the inner frame and prevent energy leakage, concentrating energy on the mirror and torsion bars, thereby increasing the quality factor Q and reducing drive voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the inner frame is made very thick to increase rigidity, then the rigidity of the inner frame is improved, but the rigidity of the outer coupling portions becomes insufficient and energy leaks to the outer frame
Solution Approach 1:
The inner frame is segmented into a frame body and multiple protrusions that extend toward the outer frame. These protrusions act as separate structural elements that provide rigidity support while isolating the frame body from direct rigid coupling with the outer frame, thereby preventing energy leakage through the coupling portions.
Solution Approach 2:
Different parts of the inner frame have different structural characteristics. The frame body has a specific thickness for overall rigidity, while the protrusions provide localized rigidity enhancement at critical coupling points. This local quality differentiation allows the frame to maintain rigidity without creating rigid pathways for energy leakage to the outer frame.
2Loss of energy
If the rigidity of outer coupling portions is increased, then energy leakage is reduced, but the complexity of the structure increases
Solution Approach 1:
The coupling structure is segmented into the frame body and multiple protrusions rather than being a single thickened coupling portion. This segmentation provides energy leakage prevention through distributed structural support while maintaining manufacturing simplicity, as the protrusions can be formed using standard semiconductor fabrication processes without requiring complex multi-step procedures.
3Reliability
If the quality factor Q is increased by reducing energy leakage, then drive voltages are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The segmented structure with protrusions provides inherent mechanical isolation that reduces energy leakage without requiring extremely tight manufacturing tolerances. The protrusions naturally create a structural configuration that prevents rigid coupling between the inner and outer frames, achieving high quality factor Q with moderate manufacturing precision suitable for standard semiconductor fabrication processes.
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 quality factor Q of the resonant structure, reducing the drive voltages needed for the inner piezoelectric actuators and improving the rocking controllability of the mirror, while maintaining or increasing deflection angles with lower power consumption.
Implementation Method 1
inner piezoelectric actuators coupled between the torsion bars and supported by the inner frame via inner coupling portions, serving as cantilevers for rocking the mirror with respect to the X-axis of the mirror
Implementation Method 2
the energy of the mirror energized by the piezoelectric actuators at the resonant frequency cannot be concentrated on the mirror, and this energy is dispersed into a frequency region around the resonant frequency
Data Source
AI summary
An optical deflector includes a mirror, an inner frame surrounding the mirror, first and second torsion bars coupled between the mirror and the inner frame, first and second inner piezoelectric actuators coupled between the first and second torsion bars supported by first and second inner coupling portions to the inner frame, and an outer frame surrounding the inner frame. The inner frame is supported by first and second outer coupling portions to the outer frame. A circumferential rib is provided on a rear surface of the inner frame. A first branch rib is provided on a rear surface of the first outer coupling portion, and a second branch rib is provided on a rear surface of the second outer coupling portion.