Light Deflector Fillet Shape Stress Distribution
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Solution Overview
Problem
Conventional light deflectors with cantilever structures face stress concentration issues at connecting parts between torsion bars and drive beams, leading to potential damage and breakdown due to increased rotational acceleration and resonance frequency, limiting the deflection angle and resolution.
Innovation Solution
Incorporating a fillet shape at both the fixed-end and free-end portions of the connecting parts between the torsion bars and drive beams, which distributes stress and reduces the maximum stress applied to the light deflector, allowing for a higher deflection angle without exceeding the breaking point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotational acceleration and resonance frequency of the mirror unit are increased to improve deflection angle and resolution, then the measurement precision and productivity are improved, but the stress concentration at the connecting parts increases leading to potential damage and reduced reliability
Solution Approach 1:
The connecting part is designed with a fillet shape (curved transition) instead of sharp corners at the junction between the drive beam and support. This curvature distributes stress more evenly throughout the connecting part, preventing stress concentration at specific points, thereby allowing the structure to withstand higher rotational acceleration and resonance frequencies without damage while maintaining improved deflection angle and resolution
2Measurement precision
If the deflection angle is increased to improve measurement precision, then the resolution is improved, but the stress on the connecting parts increases leading to potential breakdown
Solution Approach 1:
The fillet shape creates a curved transition zone in the connecting part that distributes mechanical stress more uniformly when the mirror unit deflects at larger angles. This prevents stress concentration at sharp corners, enabling the structure to accommodate increased deflection angles and their associated stresses without breakdown while maintaining high resolution
3Productivity
If the resonance frequency is increased to improve productivity and resolution, then the output and measurement precision are improved, but the stress concentration leads to reduced device lifespan
Solution Approach 1:
The fillet-shaped connecting part with its curved geometry distributes the cyclic stresses generated during high-frequency operation more evenly throughout the structure. This prevents stress concentration and fatigue failure at critical junctions, allowing the device to operate at higher resonance frequencies for extended periods, thereby improving productivity and resolution while extending device lifespan
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 configuration effectively increases the deflection angle and resolution of the light deflector by distributing stress more evenly, preventing damage and enabling higher resonance frequencies without compromising structural integrity.
Implementation Method 1
a piezoelectric actuator including an elastic beam and a mirror including a reflecting surface, which are formed as a single integrated unit on a wafer, the piezoelectric actuator also including a thin film of a piezoelectric material superposed co the elastic beam, and that causes the mirror to oscillate using the piezoelectric actuator
Data Source
AI summary
A light deflector includes a mirror unit having a reflecting surface; a pair of supports supporting the mirror unit; a pair of drive beams; a frame supporting the pair of drive beams in a cantilevered state; and connecting parts connecting the pair of drive beams to the pair of supports, respectively. Each of the connecting parts has a first area between the first axis and a corresponding drive beam of the pair of drive beams, and a second area at an opposite side of the first area relative to the first axis. The second area includes a projection projecting in a first direction opposite to a second direction toward a portion at which the corresponding drive beam is supported by the frame. The projection includes a first fillet of a fillet shape at an end proximate to a corresponding support of the pair of supports.