Piezoelectric Actuator Sawtooth Drive Waveform Ringing Suppression
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Solution Overview
Problem
Conventional light scanning apparatuses using piezoelectric actuators with sawtooth voltage drive suffer from ringing oscillations, which degrade image quality, especially when the frequency of the sawtooth waveform varies or when there are irregular waiting times between cycles, and existing frequency filtering methods fail to effectively suppress ringing in these scenarios.
Innovation Solution
A method involving the generation of a first and second staircase waveform, where the second waveform continues from the first, to create a drive signal that combines these waveforms and forms a sawtooth waveform, specifically designed to suppress ringing by aligning the oscillations of the first staircase waveform with the ringing generated by the second, thereby canceling it out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a frequency filter is applied to the entire drive waveform to suppress ringing, then ringing is reduced, but the straight line section of the sawtooth waveform becomes dull and image quality degrades
Solution Approach 1:
The drive waveform is segmented into multiple sections: a first staircase waveform section that generates ringing, a second staircase waveform section that continues from the first, and a third section. By applying different processing to different segments, the patent suppresses ringing in the main scan section while preserving the linearity needed for image quality.
Solution Approach 2:
Different waveform characteristics are applied to different sections of the drive signal. The main scan section uses a staircase waveform optimized for ringing suppression, while other sections maintain characteristics suitable for their specific functions, allowing local optimization without compromising overall performance.
2Adaptability or versatility
If the sawtooth waveform frequency varies or waiting time between cycles is irregular, then adaptability to different scanning requirements is improved, but existing frequency filtering methods fail to suppress ringing effectively
Solution Approach 1:
The patent employs dynamic waveform generation where the drive signal characteristics can change between cycles and sections. The staircase waveform parameters (number of steps, rise time, amplitude) can be adjusted dynamically to match varying scanning requirements while maintaining ringing suppression through the specific two-stage staircase structure.
Solution Approach 2:
The first staircase waveform section is designed to preemptively generate a controlled ringing oscillation that counteracts the ringing that would be generated by the second section. This preliminary action occurs before the main scan section, preparing the system to cancel out subsequent ringing regardless of frequency variations.
3Device complexity
If a simple staircase waveform is used to drive the piezoelectric actuator, then device complexity is reduced, but ringing oscillation occurs and degrades image quality
Solution Approach 1:
The patent uses periodic staircase waveforms with a specific structure: a first staircase section followed by a second staircase section. This periodic pattern is repeated for each scan cycle, providing a systematic approach to ringing suppression that maintains relatively simple waveform generation logic while effectively canceling oscillations.
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 effectively suppresses ringing in the main scan section of the sawtooth waveform without affecting the entire waveform, ensuring clear and undistorted scanning even with varying frequencies and irregular cycle times.
Implementation Method 1
an actuator having a drive source of a piezoelectric element including an upper electrode on its upper surface and a lower electrode on its lower surface
Data Source
AI summary
An actuator including a beam configured to support an object to be driven, and a drive source to which a drive signal is input, wherein the drive signal includes a drive waveform in a shape of sawtooth waveform, a rising of the drive waveform in the shape of sawtooth waveform includes a first staircase waveform and a second staircase waveform continuing from the first staircase waveform, the first staircase waveform generates oscillation of a ringing suppressing waveform for suppressing a ringing waveform to be generated in the second staircase waveform, and the object to be driven is driven to swing in a direction of rotating around the predetermined axis by driving the drive source.