MEMS Light Deflector Rib Recess Stress Relief
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Solution Overview
Problem
The existing MEMS light deflectors face a limitation in increasing the limit deflection angle of the reflector while maintaining the strength of the joining between the outer piezoelectric actuator and the inner frame, as the current designs suffer from stress concentration and damage at the junctions, restricting further enhancement of the deflection angle.
Innovation Solution
The design incorporates an encircling rib and a projecting rib on the inner frame, with an outer recess on the piezoelectric cantilever to distribute stress and an inner recess adjacent to the cantilever, enhancing the joining strength and reducing damage, allowing for a higher limit deflection angle by directing the projecting rib's end towards the cantilever's distal end and forming the inner frame in an annular shape longer in the first axis direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the joining strength between the outer piezoelectric actuator and the inner frame is increased by using an encircling rib and a projecting rib, then the structural integrity is improved, but stress concentration occurs at the step created by the projecting rib, limiting further increase of the limit deflection angle
Solution Approach 1:
The patent applies local quality by creating an outer recess at the specific location where the projecting rib forms a step. This recess is strategically positioned to address the localized stress concentration problem without modifying the overall joining structure. The recess provides localized stress relief precisely where needed, allowing the projecting rib to maintain its joining function while eliminating the harmful stress concentration at the step.
2Adaptability or versatility
If the deflection angle of the reflector is gradually increased by increasing the drive voltage, then the scanning range is improved, but the limit deflection angle is reached when damage occurs to any part of the light deflector
Solution Approach 1:
The outer recess is designed as a preventive feature that cushions against stress concentration before damage can occur. By providing this stress-relief geometry in advance, the structure can withstand higher deflection angles and drive voltages without reaching the damage threshold. The recess acts as a built-in protective feature that allows the system to operate closer to its theoretical limits without failing.
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 limit deflection angle of the reflector by reducing stress concentrations and enhancing damage control, enabling further expansion of the deflection range without compromising the structural integrity of the light deflector.
Implementation Method 1
a piezoelectric actuator which oscillates the reflector about two axes
Data Source
AI summary
A light deflector 1 includes a reflector (2), inner piezoelectric actuators (4), an inner frame (5), outer piezoelectric actuators (6), and an outer frame (7). The reflector (2) is oscillated about a first axis Ua and a second axis Ub by the inner piezoelectric actuators (4) and the outer piezoelectric actuators (6), respectively. Formed on the rear surface of the light deflector 1 is a projecting rib (52), which projects from an encircling rib (51) of the inner frame (5) and reaches a corner portion (36) of a distal end portion of a piezoelectric cantilever (13a). A vertical side (22b) has an outer recess (35). The outer recess (35) extends along the projecting rib (52) in a portion of the distal end side of the piezoelectric cantilever (13a).