Optical Deflector Zig-Zag Beams Resonance Control
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Solution Overview
Problem
Conventional optical deflectors with moveable units and piezoelectric elements face challenges in achieving uniform oscillation speed, leading to uneven brightness and image distortion due to resonance modes and harmonic components in the scanning process.
Innovation Solution
The optical deflector employs a configuration with two drive units and piezoelectric elements on zig-zag beams, where sawtooth and reverse sawtooth voltages are applied to achieve efficient oscillation about two axes, with phase differences and symmetry adjustments to suppress resonance modes and harmonic components, ensuring linear scanning and reduced vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional drive unit with piezoelectric elements is used to drive the optical deflector, then the device can achieve oscillation of the moveable unit, but the evenness of oscillation speed cannot be enhanced securely due to resonance modes and harmonic components
Solution Approach 1:
The patent applies phase difference control to convert the harmful resonance modes and harmonic components into beneficial effects. By adjusting the phase differences between drive signals to specific values, the patent suppresses unwanted resonance while enhancing the desired oscillation, thereby improving the evenness of oscillation speed. This transforms the harmful vibrational modes into a controllable parameter for optimization.
Solution Approach 2:
The patent changes the parameters of the drive signals, specifically the phase differences between signals applied to different piezoelectric elements. By optimizing these phase difference parameters, the patent achieves suppression of resonance modes and harmonic components, thereby improving the evenness of oscillation speed without changing the fundamental drive unit structure.
2Speed
If multiple piezoelectric elements are used to drive the moveable unit about one axis, then the oscillation capability is improved, but the complexity of controlling oscillation evenness increases due to multiple resonance modes
Solution Approach 1:
The patent implements a control mechanism that adjusts phase differences between drive signals based on observed oscillation characteristics. By monitoring the oscillation evenness and adjusting the phase difference parameters accordingly, the system achieves suppression of resonance modes while maintaining oscillation capability. This feedback-based optimization reduces the effective control complexity by providing a systematic approach to managing multiple resonance modes.
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 evenness of oscillation speed and linearity of scanning, reducing image distortion and improving image quality by effectively managing resonance frequencies and harmonic components.
Implementation Method 1
a plurality of piezoelectric elements disposed for the plurality of beams respectively
Data Source
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Figure 3A~4
AI summary
An optical deflection apparatus (1000) includes a moveable unit (100M) having a reflection face, and a support unit (100S). The support unit (100S) includes a zig-zag unit (210a, 210b) having a plurality of beams (108a, 108b) continuously formed with a zig-zag pattern to support the moveable unit (100M) oscillate-ably about one axis, the plurality of beams including a plurality of first beams (108a) and a plurality of second beams (108b), the first beams (108a) and the second beams (108b) being disposed adjacently, and a plurality of piezoelectric elements (11, 12) disposed for the plurality of beams (108a, 108b) respectively, the plurality of piezoelectric elements including a plurality of first piezoelectric elements (11) disposed on the plurality of the first beams (108a) one by one, and a plurality of second piezoelectric elements (12) disposed on the plurality of the second beams (108b) one by one. A a first drive signal having a first waveform is input-able to the first piezoelectric element (11) disposed on each of the first beams (108a), and a second drive signal having a second waveform is input-able to the second piezoelectric element (12) disposed on each of the second beams (108b). A time ratio of a rising period and a falling period in one cycle of the first drive signal and a time ratio of a rising period and a falling period in one cycle of the second drive signal are set with values so that a given resonance frequency among a plurality of resonance frequencies belonging to the moveable unit (100M) is set between a first frequency in the first drive signal that a signal intensity of higher frequency component of the first drive signal becomes a local minimum and a second frequency in the second drive signal that a signal intensity of higher frequency component of the second drive signal becomes a local minimum.