Piezoelectric Light Deflection Device Correcting Linearity Errors
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Solution Overview
Problem
Conventional light deflection devices using piezoelectric elements suffer from linearity errors in displacement due to voltage application, leading to inaccuracies in rotation angle and speed, resulting in image distortion and failure in optical scanning applications.
Innovation Solution
A light deflection device with a piezoelectric drive circuit that applies specific waveforms of drive voltage to the piezoelectric element, featuring periods of positive and negative slopes, which are adjusted based on the piezoelectric constant to correct for the linearity errors and maintain consistent rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piezoelectric element is used to drive the reflector, then the reflector can be rotated to deflect light, but linearity errors occur in the displacement of the piezoelectric element with respect to the applied voltage, resulting in inaccurate rotation angles and speeds
Solution Approach 1:
The patent applies parameter changes by modifying the drive voltage waveform parameters (slope periods) to compensate for the non-linear piezoelectric characteristics. The circuitry outputs drive voltage waveforms with adjusted positive and negative slope periods that account for the piezoelectric element's non-linear displacement response, thereby achieving accurate rotation angles and speeds despite the inherent linearity errors of the piezoelectric material
2Ease of operation
If the piezoelectric element deforms according to a simple sinusoidal waveform, then the drive circuit is simple, but the rotation speed varies and image distortion occurs
Solution Approach 1:
The patent applies dynamics by transitioning from a static, simple sinusoidal waveform to a dynamic, adjustable waveform with variable slope periods. The drive circuit generates waveforms where the positive and negative slope periods are dynamically adjusted based on the piezoelectric element's characteristics, enabling consistent rotation speed and eliminating image distortion while maintaining circuit simplicity
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
The solution effectively reduces deflection-angle errors, ensuring linear deflection-angle changes and maintaining consistent rotation speed, thereby improving the accuracy and quality of optical scanning and image projection.
Implementation Method 1
a piezoelectric element that is deformable according to a waveform of a drive voltage. The piezoelectric element is configured to drive the reflector by deforming of the piezoelectric element
Data Source
AI summary
A light deflection device includes a reflector; a drive beam supporting the reflector such that the reflector is movable; a supporting section supporting the drive beam; and a piezoelectric drive circuit disposed on the drive beam. The light deflection device further includes circuitry configured to output a first drive-voltage waveform and a second drive-voltage waveform to the piezoelectric drive circuit. The first drive-voltage waveform has a period of a positive slope within one cycle, the period of the positive slope includes a period of a first slope and a period of a second slope different from the first slope. The second drive-voltage waveform has a period of a negative slope within one cycle, and the period of the negative slope includes a period of a third slope and a period of a fourth slope different from the third slope.