Semi-resonant Ultrasonic Driver for Stable Precision Positioning
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Solution Overview
Problem
Existing ultrasonic driving systems for precise positioning, such as those used in image sensors and optical camera systems, operate at high speeds that are too fast for stable and high-quality image capture due to unstable motion and poor step resolution.
Innovation Solution
A semi-resonant driving system that utilizes an asymmetrical structure with two bending modes of different resonant frequencies, where one mode operates at resonance and the other at partial resonance, with phase-shifted vibration signals to control the direction of a movable element, enabling precise and stable movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic drivers operate at high speeds (100mm/s to 1000mm/s), then productivity is improved, but measurement precision and stability deteriorate due to unstable motion and poor step resolution
Solution Approach 1:
The patent utilizes mechanical vibration at resonant frequency to drive the structure. By operating at the resonant frequency of the first bending mode, the system achieves amplified vibration response with smaller actuator input, enabling precise control of the movable element's position while maintaining stable motion characteristics
Solution Approach 2:
The patent changes the operating parameters by operating at resonant frequency rather than high speed. The vibration frequency is set to match the resonant frequency of the structure, which fundamentally changes the motion characteristics from high-speed linear motion to resonant vibration-based controlled motion, achieving both precision and stability
2Productivity
If ultrasonic drivers operate at high speeds, then productivity is improved, but reliability deteriorates due to unstable motion
Solution Approach 1:
The system employs mechanical vibration at the resonant frequency of the structure's first bending mode. This resonant vibration creates stable and predictable motion patterns that significantly improve motion stability compared to high-speed operation, ensuring reliable position control of the movable element
Solution Approach 2:
The patent utilizes periodic vibration action at the resonant frequency. The periodic nature of resonant vibration ensures consistent and repeatable motion cycles, which enhances the reliability and stability of the driving system by eliminating the instability associated with high-speed operation
3Manufacturing precision
If a structure operates at resonance in one bending mode, then manufacturing precision is improved through amplified vibration response, but device complexity increases due to need for multi-mode control
Solution Approach 1:
The patent employs an asymmetrical structure design where the first and second bending modes have different resonant frequencies. This asymmetry allows independent control of each mode, enabling precise vibration response in the primary bending mode while using the second mode for directional control, thereby managing device complexity through intentional asymmetric design
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 system achieves more precise and stable movement, overcoming the limitations of prior art by allowing for smaller and more precise steps, making it suitable for applications like auto-focus and auto-zoom systems.
Implementation Method 1
piezoelectric devices include a ceramic that is formed into a capacitor that changes shape when charged and discharged
Implementation Method 2
the first bending mode resonant frequency in the ultrasonic range with a plus or minus 90-degree phase shift
Implementation Method 3
The structure has at least one point to frictional couple to and drive a movable element
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3
AI summary
A driving system in accordance with embodiments of the present invention includes a structure and a vibration system. The structure has at least one point to frictional couple to and drive a movable element in one of at least two directions. The structure also has at least two bending modes which each have a different resonant frequency. The vibration system applies two or more vibration signals which are at a vibration frequency to each of the bending modes of the structure. The vibration frequency is substantially the same as one of the resonant frequencies. At the vibration frequency one of the bending modes of the structure is vibrating substantially at resonance and the other of the bending modes of the structure is vibrating at partial resonance. The vibration system adjusts a phase shift between the two or more applied vibration signals to control which one of the at least two directions the moveable element is moved.