Optical Deflection Device with Zig-Zag Beams for Constant Scanning Speed
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Solution Overview
Problem
Existing optical deflection devices face issues with uneven scanning speed due to varying piezoelectric deformation caused by voltage application during two-dimensional scanning, leading to non-linear optical scanning angles and image distortion.
Innovation Solution
The optical deflection device employs a pair of zig-zag beams with piezoelectric elements, where different sawtooth wave voltages are applied to each beam to flexibly deform them, allowing for adjustable oscillation of a reflection mirror at a constant speed by adjusting the voltage based on the piezoelectric constant, ensuring consistent scanning speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sawtooth wave voltage is applied to piezoelectric elements for vertical scanning, then optical scanning is achieved, but scanning speed becomes uneven due to varying piezoelectric deformation
Solution Approach 1:
The patent modifies the voltage waveform parameters applied to the piezoelectric elements. Instead of using a standard sawtooth wave, the invention uses a corrected waveform where the voltage change amount varies at different time points during the scanning period. This parameter modification compensates for the non-linear piezoelectric deformation characteristics, ensuring that the optical scanning angle changes linearly with time and achieving uniform scanning speed.
2Power
If resonance drive is used for horizontal scanning, then greater scanning angle is achieved with lower voltage, but flapping occurs in sub-scanning direction due to harmonic wave interference
Solution Approach 1:
The patent introduces a feedback control mechanism where the drive signal for horizontal scanning is adjusted based on the interaction between the resonance frequency and harmonic waves. By detecting the flapping phenomenon caused by frequency interference and providing feedback to the drive unit, the system can modify the drive signal to eliminate the harmful resonance interaction, thereby stabilizing the scanning motion while maintaining energy efficiency.
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 enables uniform image display by maintaining constant scanning speed and preventing image distortion, even when manufacturing errors occur, without the need for dedicated speed detection devices or complex signal processing.
Implementation Method 1
a plurality of piezoelectric elements disposed on the first beams and the second beams of the zig-zag beams, a voltage application unit to apply a first waveform voltage to the piezoelectric elements disposed on the first beams, and a second waveform voltage to the piezoelectric elements disposed on the second beams to flexibly deform the first beams and the second beams of the zig-zag beams
Data Source
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AI summary
An optical deflection device (2) includes a pair of zig-zag beams (22a, 22b), each of the zig-zag beams (22a, 22b) including a plurality of first beams (A) and a plurality of second beams (B) arranged with a zig-zag pattern, a frame (21) to support the zig-zag beams (22a, 22b), a reflection mirror (26), supported by the zig-zag beams (22a, 22b), to deflect light, a plurality of piezoelectric elements (23) disposed on the first beams (A) and the second beams (B) of the zig-zag beams (22a, 22b), a voltage application unit (422) to apply a first waveform voltage to the piezoelectric elements (23) disposed on the first beams (A), and a second waveform voltage to the piezoelectric elements (23) disposed on the second beams (B) to flexibly deform the first beams (A) and the second beams (B) of the zig-zag beams (22a, 22b). The reflection mirror (26) is oscillate-able by the flexible deformation of the first beams (A) and the second beams (B). The voltage application unit (422) adjusts voltage applied to the piezoelectric elements (23) depending on piezoelectric constant of the piezoelectric elements (23) to set the oscillation of the reflection mirror (26) at a constant speed.