MEMS Mirror Shock Protection via Planar Stop Structures
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Solution Overview
Problem
Micro-electro-mechanical mirror devices face robustness issues due to shocks in directions perpendicular to the rotation axis, particularly when the tiltable structure is rotated, which can cause damage to elastic decoupling elements and compromise the device's functionality.
Innovation Solution
A micro-electromechanical device with a tiltable structure featuring a planar stop structure and vertical stop structure, including projection/abutment surface pairs and stop pillars, that limit movement during rotation and provide shock protection by engaging with the tiltable structure and driving arms, ensuring robustness both in rest and rotated positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the tiltable structure is made movable to enable light beam deflection, then the device achieves optical functionality, but it becomes vulnerable to shocks in directions perpendicular to the rotation axis
Solution Approach 1:
The patent applies preliminary action by pre-positioning stop structures (projections and abutment surfaces) between the tiltable structure and fixed structure before shocks occur. These stop structures are arranged to engage with the tiltable structure in advance, creating pre-defined limits to movement that prevent excessive displacement during shock events, thereby protecting the elastic decoupling elements before damage can occur.
Solution Approach 2:
The patent introduces stop structures as intermediary elements positioned between the tiltable structure and the fixed structure. These intermediaries (projections on the fixed structure and corresponding abutment surfaces on the tiltable structure, or vice versa) act as mediators that limit relative movement in directions perpendicular to the rotation axis, absorbing shock energy and preventing direct transmission of harmful forces to the elastic decoupling elements.
2Reliability
If stop structures are added to limit movement and protect against shocks, then robustness is improved, but device complexity increases
Solution Approach 1:
The patent merges the stop structures with existing components of the device. The projections and abutment surfaces are integrated into the fixed structure and tiltable structure respectively, combining the shock protection function with the structural framework that already exists. This integration approach avoids adding completely separate, independent protection mechanisms, thereby limiting the increase in overall device complexity while still achieving the desired robustness.
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 device achieves high robustness against shocks in all directions, preventing excessive movement and stress on elastic decoupling elements, thereby enhancing the durability and functionality of the micro-electro-mechanical mirror devices.
Implementation Method 1
Each arm carries a piezoelectric band, and adjacent piezoelectric bands are biased by voltages of opposite polarity. Due to the properties of piezoelectric materials, biasing causes the deformation in opposite directions (upwards and downwards) of adjacent arms and the consequent rotation of the suspended frame in a first direction about the horizontal axis B.
Implementation Method 2
The tiltable structure 22 is elastically coupled to a frame 24' belonging to a fixed structure 24 via supporting elements 25A, 25B and elastic suspension elements 26A, 26B.
Data Source
AI summary
This disclosure pertains to a microelectromechanical systems (MEMS) device with a tiltable structure, a fixed supporting structure, and an actuation structure with driving arms connected to the tiltable structure by elastic decoupling elements. Described herein, particularly, is a planar stop structure between the driving arms and the tiltable structure, which functions to limit movement in the tiltable plane. This stop structure includes a first projection/abutment surface pair formed by a projection extending from a driving arm and an abutment surface formed by a recess in the tiltable structure. The projection and abutment surface are adjacent and spaced apart in the device's rest condition.