Optical Deflector Ringing Suppression via Frequency Filtering
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Solution Overview
Problem
Existing optical deflectors using piezoelectric actuators with sawtooth waveforms suffer from ringing phenomena due to mechanical natural frequency variations, leading to non-uniform scanning speeds and image deformation, as the removal of harmonic components based on predetermined frequencies is insufficient to suppress these issues.
Innovation Solution
An optical deflector with a control unit that detects the mechanical natural frequency using a detecting piezoelectric element and adjusts the drive voltage by removing specific frequency components, including the natural frequency and its harmonics, to maintain scanning speed uniformity and prevent ringing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If voltage signals of a sawtooth waveform are applied to the piezoelectric actuators, then the scanning speed uniformity is improved, but a ringing phenomenon occurs due to mechanical natural frequency resonance
Solution Approach 1:
The patent extracts and removes the mechanical natural frequency and its harmonic components from the sawtooth waveform voltage signal through filtering. This eliminates the resonant frequencies that cause ringing while preserving the scanning speed uniformity benefits of the sawtooth waveform.
Solution Approach 2:
The patent uses a detecting piezoelectric element to detect the actual mechanical natural frequency of the mirror part, and feeds this information back to dynamically adjust the filtering parameters. This ensures that the removed frequency components accurately match the actual resonant frequencies, effectively suppressing ringing.
2Device complexity
If the mechanical natural frequency is removed based on a predetermined value, then the device complexity is reduced, but the reliability deteriorates due to manufacturing errors and frequency variations
Solution Approach 1:
The patent employs a detecting piezoelectric element to detect the actual mechanical natural frequency and uses this detected value to dynamically adjust the filtering parameters. This feedback mechanism ensures reliable ringing suppression despite manufacturing variations and frequency drift, while keeping the device structure relatively simple.
Solution Approach 2:
The system uses its own detecting piezoelectric element to automatically detect and compensate for frequency variations without requiring external calibration or complex adjustment mechanisms. The system self-adjusts to maintain optimal performance.
3Reliability
If a detecting piezoelectric element is added to detect the mechanical natural frequency, then the reliability of ringing suppression is improved, but the device complexity increases
Solution Approach 1:
The detecting piezoelectric element serves multiple functions: it detects the mechanical natural frequency, monitors the vibration state of the mirror part, and provides feedback for dynamic filtering adjustment. This multi-functionality justifies the added component by providing significant reliability improvement.
Solution Approach 2:
The detecting piezoelectric element creates a closed-loop feedback system that automatically adjusts the filtering parameters based on actual conditions. This feedback mechanism provides high reliability in ringing suppression while keeping the control logic relatively simple through automated adjustment.
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 solution effectively suppresses ringing phenomena and maintains scanning speed uniformity by dynamically adjusting the drive voltage based on actual mechanical frequencies, ensuring consistent image quality without increasing deflection angles.
Implementation Method 1
a piezoelectric actuator of which one end is connected to the mirror part, of which the other end is connected to the support part, and which swings the mirror part about a predetermined axis relative to the support part by piezoelectric driving
Implementation Method 2
a detecting piezoelectric element which outputs a detection voltage based on bending deformation due to vibration transmitted by the piezoelectric actuator
Data Source
AI summary
An optical deflector is provided which can effectively suppress occurrence of a ringing phenomenon when a piezoelectric actuator is driven with a voltage signal of a sawtooth waveform. An optical deflector A1 includes a control circuit 20 that detects a mechanical natural frequency relevant to swinging about a second axis X2 of a movable part 9. The control circuit 20 applies a voltage signal of a sawtooth waveform from which the natural frequency and a harmonic component thereof are removed to outside piezoelectric actuators 10a and 10b. The control circuit 20 removes a frequency component, which is equal to or greater than a second threshold value G2 within a predetermined frequency range out of frequency components of a voltage signal output from a detecting piezoelectric body 62, from a drive voltage.