Optical Deflection Apparatus Resonance Control via Piezoelectric Drive
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Solution Overview
Problem
Existing optical deflection apparatuses face challenges in achieving uniform rocking speed around one axis, leading to non-linear optical scanning and image quality degradation due to resonance modes and high-frequency vibrations.
Innovation Solution
The apparatus employs a moving part with a reflection surface and a supporting part having tortuous beams, with two drive signals having specific waveforms applied to adjacent piezoelectric members, ensuring that at least one mechanical resonance frequency falls within a frequency band where high-frequency signal intensities are minimized, and adjusting phase differences and symmetries to reduce resonance-related distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drive signals are applied to piezoelectric members in optical deflection apparatus, then the mirror can be driven for optical scanning, but resonance modes and high-frequency vibrations occur causing non-uniform rocking speed and image quality degradation
Solution Approach 1:
The patent applies parameter changes by carefully selecting the frequency of drive signals to avoid mechanical resonance frequencies of the system. The drive signal frequency is chosen such that it does not coincide with natural frequencies of the mirror-supporting part assembly, thereby preventing resonance-induced vibrations and achieving uniform rocking speed throughout the optical scanning range.
Solution Approach 2:
The patent employs periodic drive signals with specific frequencies to actuate the piezoelectric members. By using periodic sinusoidal signals at carefully selected frequencies, the system achieves smooth, uniform rocking motion of the mirror while avoiding excitation of high-frequency resonance modes that would degrade image quality.
2Measurement precision
If piezoelectric members are used to drive the mirror for optical scanning, then precise control is achieved, but high-frequency vibrations occur leading to brightness unevenness and image distortions
Solution Approach 1:
The patent modifies the frequency parameters of the drive signals applied to piezoelectric members. By selecting drive frequencies that avoid the mechanical resonance frequencies of the mirror-support structure, the system maintains precise control over mirror positioning while eliminating high-frequency vibrations that cause brightness unevenness and image distortions during optical scanning.
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 enhances the uniformity of rocking speed and linearity of optical scanning, reducing image distortions and brightness unevenness, thereby improving image quality and scanning efficiency.
Implementation Method 1
a plurality of piezoelectric members separately provided on the respective beams
Implementation Method 2
at least one mechanical resonance frequency of a system including the moving part and the supporting part is included in a frequency band where signal intensities of high-frequency components of the two drive signals become local minimum values
Data Source
Figure 1
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Figure 3A~4
AI summary
An optical deflection apparatus includes: a moving part having a reflection surface; a supporting part swingably supporting the moving part around one axis and having tortuous parts having respective plural beams connected in series to each other in a tortuous manner; and a plurality of piezoelectric members separately provided on the respective beams. Further, two drive signals having predetermined waveforms are respectively applied in parallel to two piezoelectric members separately provided on the beams adjacent to each other, and at least one mechanical resonance frequency of a system including the moving part and the supporting part is included in a frequency band where signal intensities of high-frequency components of the two drive signals become local minimum values.