Optical Deflector Coupling Bars at Vibration Nodes
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Solution Overview
Problem
The existing one-dimensional optical deflectors suffer from reduced endurance of coupling bars due to resonant vibration loops and nodes, leading to degradation and increased inertial moment, which affects the stability and precision of the mirror's rocking operation.
Innovation Solution
The optical deflector design incorporates first and third coupling bars along nodes of resonant vibration and second and fourth coupling bars along other nodes, with piezoelectric actuators strategically placed on loops to minimize vibration at nodes and enhance endurance, using a silicon-on-insulator substrate and MEMS technology for construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coupling bars are arranged along the X-axis perpendicular to the Y-axis (prior art configuration), then the structure is simple and easy to manufacture, but the coupling bars are located at loop portions of resonant vibration which degrades their endurance
Solution Approach 1:
The patent changes the symmetric arrangement of coupling bars (prior art had two bars at ±90°) to an asymmetric arrangement where four coupling bars are positioned at specific angles (±θ and ±(90°-θ)) relative to the Y-axis. This asymmetric configuration strategically places coupling bars at node portions of resonant vibration rather than loop portions, thereby improving endurance while maintaining manufacturability.
Solution Approach 2:
The patent considers the dynamic resonant vibration characteristics of the movable ring-shaped frame and uses this knowledge to optimize the static arrangement of coupling bars. By analyzing the resonant vibration patterns (identifying loop and node portions), the coupling bars are positioned to coincide with node portions where vibration amplitude is minimal, thus improving reliability under dynamic operating conditions.
2Stability of the object's composition
If reinforcement is attached to the back surface of the mirror to suppress deformation, then the mirror deformation is suppressed, but the inertial moment is substantially increased which degrades coupling bar endurance further
Solution Approach 1:
The patent extracts the function of suppressing resonant vibration from the reinforcement structure and transfers it to the coupling bar arrangement. Instead of adding reinforcement that increases inertial moment, the patent uses the strategic positioning of coupling bars at node portions to naturally suppress vibration, thereby avoiding the need for additional reinforcement and its associated negative effects.
Solution Approach 2:
The coupling bars serve as intermediaries that both support the movable ring-shaped frame and suppress resonant vibration. By positioning them at node portions, they act as vibration dampers without requiring separate reinforcement structures, thus mediating between the need for structural support and vibration suppression while avoiding increased inertial moment.
3Strength
If coupling bars are positioned at loop portions of resonant vibration, then the structure provides adequate support, but the maximum vibration amplitudes at these locations degrade the endurance of the coupling bars
Solution Approach 1:
The patent applies dynamic analysis of resonant vibration to determine the optimal static positions of coupling bars. By identifying node portions where vibration amplitude is minimal during resonant operation, the coupling bars are positioned to experience minimal dynamic stress, thereby improving endurance while maintaining adequate support strength through the four-bar configuration.
Solution Approach 2:
The patent changes the positional parameters of the coupling bars from the prior art configuration (at ±90° to Y-axis) to a new configuration at specific angles (±θ and ±(90°-θ)) that correspond to node portions of resonant vibration. This parameter change optimizes both support strength and endurance by aligning coupling bar positions with the dynamic vibration characteristics of the system.
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 enhances the endurance of coupling bars, stabilizes the rocking operation of the mirror, and maintains effective deflection while suppressing deformation, ensuring precise and durable optical deflection performance.
Implementation Method 1
Piezoelectric actuators (not shown) formed on the entire movable ring-shaped frame 2 associated with the torsion bars 3a and 3b are of a resonance type.
Implementation Method 2
In a resonance state, when the rocking frequency 'f' of the piezoelectric actuators is close to the natural frequency of a mechanically-vibrating system of the mirror 1, the deflection angle of the mirror 1 with respect to the Y-axis can be increased.
Data Source
AI summary
In an optical deflector including a mirror, a movable ring-shaped frame surrounding the mirror, a pair of torsion bars connected between the mirror and the movable ring-shaped frame and oppositely arranged along a rocking direction of the mirror, a support body surrounding the movable ring-shaped frame, and piezoelectric actuators for rocking the mirror through the torsion bars along the rocking direction, first, second, third and fourth coupling bars are connected between the support body and the movable ring-shaped frame. The first and third coupling bars are oppositely arranged along a first direction obtained by inclining the rocking direction by a first predetermined angle between +30° and +45°, and the second and fourth coupling bars are oppositely arranged along a second direction obtained by inclining the rocking direction by a second predetermined angle between −30° and −60°.