Phacoemulsification Handpiece Resonance Control
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Solution Overview
Problem
Phacoemulsification devices face inefficiencies due to shifts in resonant frequency caused by changes in mechanical load, heating, and aging of piezoceramic elements, leading to suboptimal energy transformation into mechanical energy and increased reactive power, resulting in reduced efficiency and potential thermal stress during cataract emulsification.
Innovation Solution
A phacoemulsification device with a handpiece equipped with piezoelectric elements and a controller that maintains oscillation at the natural frequency, using immediate feedback to adjust the power amplifier and reduce reactive power, along with a transformer for signal transmission and controlled energy supply to minimize thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the excitation frequency is regulated based on phase angle detection to maintain resonance, then the handpiece can operate near resonant frequency, but the regulation is slow and reactive power remains relatively high
Solution Approach 1:
The patent implements immediate feedback by detecting the voltage induced on the piezoelectric elements during operation and using this actual value to control the power amplifier in real-time. This closed-loop feedback system allows the handpiece to maintain oscillation at its natural frequency without the slow phase angle detection method, thereby reducing reactive power while ensuring reliable resonance maintenance.
Solution Approach 2:
The patent replaces the traditional mechanical/electrical phase angle detection and frequency regulation system with an electromechanical substitution approach. By utilizing the induced voltage on the piezoelectric elements as a direct indicator of natural frequency oscillation and feeding this back to the power amplifier, the system eliminates the need for separate phase detection and frequency adjustment mechanisms, reducing reactive power consumption.
2Adaptability or versatility
If the cutting tip is operated with forced vibration away from natural frequency to accommodate load changes, then the system can adapt to varying mechanical loads, but energy transformation efficiency decreases
Solution Approach 1:
The patent implements a dynamic control system where the power amplifier receives immediate feedback from the induced voltage on the piezoelectric elements and adjusts the excitation in real-time. This dynamic adaptation allows the handpiece to maintain oscillation at its natural frequency despite varying mechanical loads, ensuring optimal energy transformation efficiency while accommodating load changes through continuous real-time control rather than fixed frequency operation.
Solution Approach 2:
The system utilizes the induced voltage generated by the piezoelectric elements during operation as a self-diagnostic signal. This induced voltage serves as an actual value that automatically indicates whether the handpiece is oscillating at its natural frequency, enabling the control system to self-adjust without external intervention or complex sensing mechanisms, thereby maintaining energy efficiency under varying loads.
3Measurement precision
If multiple successive measuring points are recorded to determine phase angle, then the phase angle can be calculated, but the regulation speed becomes slow
Solution Approach 1:
The patent implements immediate feedback by using the voltage induced on the piezoelectric elements during operation as a direct measure of oscillation frequency. This single-point feedback measurement eliminates the need for recording multiple successive measuring points to calculate phase angle, enabling real-time regulation speed while maintaining the precision needed to detect natural frequency oscillation and adjust the power amplifier accordingly.
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 achieves higher efficiency by maintaining oscillation at the natural frequency, reducing reactive power, and minimizing thermal stress during the emulsification process, ensuring optimal energy transformation and reduced risk of thermal damage.
Implementation Method 1
If a voltage is applied to these piezoceramic elements, a change in length can be brought about due to the piezoelectric effect, so that a needle connected to the piezoceramic can be deflected in the longitudinal direction.
Implementation Method 2
In order to achieve the greatest possible amplitudes for the cutting tip, the piezoelectric elements are operated in the range of the resonant frequency of the handpiece.
Data Source
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AI summary
The invention relates to a phacoemulsification device, comprising: - a hand piece having a cutting tip for emulsifying a lens, wherein the tool holder is provided with piezoelectric elements for deflecting the cutting tip, - a regulator, the input of which is electrically connected to the tool holder, for receiving an actual value that is proportional to the voltage induced on the piezoelectric elements of the tool holder that is constantly oscillating on the natural frequency thereof, said regulator being suitable for comparing the actual value with a predetermined target value, thus determining an actuating variable, - a power amplifier, the input of which is connected to the regulator in order to receive the actuating variable, and the output of which is connected to the tool holder, wherein the tool holder may be actuated simultaneously with the receipt of the actual value and a power output to the tool holder being able to occur, such that a direct feedback coupling may be attained, thus enabling the tool holder to constantly oscillate at the natural frequency thereof with a deflection of the cutting tip corresponding to the actuating variable.