Meander Piezoelectric Actuator Crossing Bar Alignment
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Solution Overview
Problem
Existing optical deflectors with meander-type piezoelectric actuators face challenges in accurate alignment due to manufacturing fluctuations, leading to resonance issues and potential deformation from external impacts, which affect the mirror's deflection accuracy and reliability.
Innovation Solution
The introduction of crossing bars that couple specific folded portions of the piezoelectric cantilevers to prevent Z-axis motion asymmetry, enhancing the spacing between cantilevers and reducing resonance with abnormal modes, thus maintaining the mirror's alignment and preventing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If meander-type piezoelectric actuators are used to rock the mirror, then the mirror deflection function is achieved, but manufacturing fluctuations cause misalignment of cantilevers leading to resonance issues and reduced precision
Solution Approach 1:
A crossing bar is introduced as an intermediary component to couple folded portions of piezoelectric cantilevers from opposite actuators. This mediator maintains symmetric Z-axis positions of folded portions, preventing resonance caused by asymmetric Z-axis motions while being simple to manufacture and integrate into the existing actuator structure
Solution Approach 2:
The design changes the positional parameters of folded portions by coupling them with crossing bars to maintain symmetric Z-axis positions. This parameter control ensures that folded portions remain at predetermined symmetric positions, eliminating resonance issues without requiring complex manufacturing processes
2Area of stationary object
If meander-type piezoelectric actuators are positioned close to each other, then the device size is reduced, but external impacts cause displacement and deformation leading to interference with the mirror
Solution Approach 1:
The crossing bar structure provides beforehand structural reinforcement by coupling folded portions of cantilevers from opposite actuators. This pre-established coupling prevents excessive displacement and deformation under external impacts, protecting the fragile piezoelectric actuators from breaking while maintaining compact device dimensions
3Manufacturing precision
If accurate symmetric alignment of cantilevers is required to prevent resonance, then manufacturing complexity and cost increase, but without it resonance occurs at abnormal frequencies
Solution Approach 1:
The crossing bar serves as a simple intermediary that automatically enforces symmetric positioning of folded portions without requiring complex alignment control during manufacturing. The coupling structure inherently maintains symmetric Z-axis positions, eliminating the need for precise manual or automated alignment processes
Solution Approach 2:
The design shifts from requiring precise positional parameters of folded portions to using a coupling mechanism that automatically maintains symmetric Z-axis positions. This parameter control through coupling rather than precise manufacturing reduces alignment control complexity while preventing resonance
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 solution enhances the resonance at the natural frequency of the normal mode while avoiding interference with the mirror, maintaining the deflection angle's amplitude and preventing the meander-type piezoelectric actuators from being twisted or deformed by external impacts.
Implementation Method 1
a pair of meander-type piezoelectric actuators 3a and 3b coupled between the fixed frame 2 and the mirror 1 and serving as cantilevers for rocking the mirror 1 around an X-axis
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
In an optical deflector including a mirror (1), a fixed frame (2) surrounding the mirror (1), and first and second piezoelectric actuators (3a, 3b) of a meander-type provided opposite to each other with respect to the mirror (1), for rocking the mirror (1) around an axis on a plane of the fixed frame (2), the first piezoelectric actuator (3a) includes a plurality of first piezoelectric cantilevers (3a-1, 3a-2, 3a-3, 3a-4) folded at first folded portions (Fa12, Fa23, Fa34) and coupled to the fixed frame (2), and the second piezoelectric actuator (3b) includes a plurality of second piezoelectric cantilevers (3b-1, 3b-2, 3b-3, 3b-4) folded at second folded portions (Fb12, Fb23, Fb34) and coupled to the fixed frame (2). The optical deflector further includes at least one first crossing bar (4) coupled between one of the first folded portions (Fa12, Fa23, Fa34) and one of the second folded portions (Fb12, Fb23, Fb34) symmetrically located with respect to the mirror (1).