Piezoelectric Light Deflector with Asymmetric Rib
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Solution Overview
Problem
Existing light deflector technologies face challenges in achieving a wide deflection angle and high resonance frequency while maintaining mechanical strength and precision, often leading to increased size, cost, and risk of failure due to excessive misalignment of torsion bars and deformation forces.
Innovation Solution
The design misaligns the center of gravity of the mirror unit relative to its shape, allowing for enhanced rotational moment without increasing torsion bar misalignment, using a cylindrical rib to reinforce the mirror unit and reduce distortion, and employing a unimorph drive bar structure with piezoelectric materials to achieve large amplitude oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the diameter of the mirror unit is increased to improve deflection angle, then the deflection angle increases, but the mirror unit becomes more prone to deformation and requires increased torsion bar misalignment which increases asymmetry and stress
Solution Approach 1:
The patent introduces asymmetry by providing a rib on only one side of the mirror unit (the side opposite to the light reflection plane). This asymmetric reinforcement structure compensates for the increased stress and deformation risks associated with larger mirror diameters, allowing the mirror unit to achieve greater deflection angles while maintaining mechanical strength without requiring increased torsion bar misalignment.
2Speed
If the drive frequency is increased to a few kHz to tens of kHz to improve speed, then the resonance frequency increases, but the mirror unit deforms and the optically-required precision cannot be maintained
Solution Approach 1:
The patent employs a curved or arched rib structure on the mirror unit. This curved reinforcement structure enhances the rigidity and resistance to deformation at high drive frequencies, allowing the mirror unit to maintain its optically-required precision even when operated at resonance frequencies of a few kHz to tens of kHz.
3Force
If misalignment of torsion bars is increased to enhance rotational moment, then the moment of oscillation increases, but the asymmetry level increases and extra deformation force is applied to the torsion bars
Solution Approach 1:
The patent segments the mirror unit structure by adding a separate rib component on one side. This segmentation allows the reinforcement function to be separated from the torsion bar positioning, enabling enhanced rotational moment through the rib's asymmetric placement without requiring increased misalignment of the torsion bars, thereby avoiding extra deformation forces and reducing the risk of failure.
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 approach prevents breakage and failure, improves optical scanner performance by increasing the rotational amplitude and resonance frequency while maintaining mechanical strength and precision, and reduces power consumption.
Implementation Method 1
By applying voltage to the piezoelectric material fixed to the drive bar, the piezoelectric material expands and contracts and the drive bar bends and deforms
Implementation Method 2
When the mirror unit rotates and oscillates, the torsion bars twist and deform mainly around the axis and support the rotation and oscillation of the mirror unit
Implementation Method 3
a rib is provided on the other side of the mirror unit with which the light reflection plane is not provided to enhance the mechanical strength of the mirror unit and reduce the dynamic distortion of the light reflection plane
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A light deflector (2) includes a base (16), a mirror unit (6) having a light reflection plane (4), a pair of elastic supporting members (8, 10) each having one end attached to the mirror unit (6) and configured to support the mirror unit (6) in a rotatable and oscillatable manner, and a pair of drive bars (12, 14) each having one end attached to the other end of corresponding one of the elastic supporting members (8, 10) and the other end attached to the base (16) in a cantilever state, the pair of drive bards (12, 14) being configured to deform by application of voltage, where the mirror unit (6) rotates and oscillates as deformation of the drive bars (12, 14) caused by application of voltage is transferred to the mirror unit (6) through the elastic supporting members (8, 10).