Ultrasonic Phaco Handpiece Phase Measurement Circuit
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Solution Overview
Problem
Conventional phacoemulsification systems face challenges in maintaining optimal power transfer efficiency due to variations in phase angle caused by changes in load during surgery, requiring precise measurement and adjustment of the phase angle between voltage and current to ensure consistent energy transfer.
Innovation Solution
A method and system for determining the phase relationship between the voltage and current of a piezoelectric phacoemulsification handpiece using a master clock to correlate a reference amplitude component with a point in time, determining a phase count, and resetting the clock upon completion of a phase measurement, eliminating the need for integrators and A/D converters and reducing calibration requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase measurement methods using integrators and A/D converters are used, then phase angle can be measured, but device complexity increases and calibration requirements increase
Solution Approach 1:
The patent extracts and eliminates the unnecessary integrators and A/D converters from the phase measurement system. By directly measuring the phase angle between voltage and current signals using simplified circuitry, the system removes complex components while maintaining measurement capability, thereby reducing device complexity without sacrificing measurement precision.
Solution Approach 2:
The patent replaces the conventional electronic measurement system (integrators and A/D converters) with a simplified electrical measurement approach using direct signal comparison and phase detection circuitry. This substitution eliminates mechanical and complex electronic components, reducing overall system complexity while achieving accurate phase measurement.
2Measurement precision
If conventional phase measurement methods are used, then phase angle can be determined, but manufacturing precision requirements increase due to calibration needs
Solution Approach 1:
The patent removes the calibration-dependent components (integrators and A/D converters) from the measurement system. By using direct phase comparison methods that do not require integration or digital conversion, the system eliminates the need for precise calibration procedures, thereby reducing manufacturing precision requirements while maintaining measurement accuracy.
Solution Approach 2:
The measurement system is designed to be self-calibrating or calibration-free by using direct signal comparison techniques. The system automatically determines phase angle without requiring external calibration standards or procedures, making the manufacturing process less demanding while ensuring consistent measurement precision.
3Ease of operation
If phase angle variations are not compensated, then system operation is simpler, but power transfer efficiency decreases
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the phase angle between voltage and current signals and uses this information to adjust the operating frequency or impedance matching. This feedback loop automatically compensates for phase variations caused by load changes, maintaining optimal power transfer efficiency without requiring complex manual intervention, thus balancing ease of operation with energy efficiency.
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 provides precise, real-time phase measurement independent of operating frequency, reducing component variations and improving power control efficiency, reliability, and scalability by eliminating the need for additional hardware and calibration.
Implementation Method 1
The hollow needle 15 is generally driven or excited by an applied AC voltage creating a piezoelectric effect in crystals
Implementation Method 2
correlating a reference amplitude component of the digital representation with a point in time using a master clock
Data Source
Figure 1a
Figure 1b
Figure 2~3
AI summary
In one embodiment, a method for determining the voltage current phase relationship of a piezoelectric phacoemulsification handpiece generally includes the steps of obtaining an analog AC voltage signal corresponding to the operating AC voltage of a piezoelectric handpiece along with an analog AC current signal corresponding to the operating AC current of the piezoelectric handpiece. Using reference detection circuits, a digital voltage signal and a digital current signal is produced. A synchronous sample clock is taken that has a frequency that is 2N times faster than the frequency of the operating ultrasonic handpiece (i.e., driving frequency), where N is the number of digital bits allocated to the sample clock.. This clock measures the time between onsets of a voltage and current cycle. This time value equates to the phase time delta between the two signals. Dividing the synchronous sample clock to obtain the driving frequency ensures the signals are synchronous. Further dividing the end count value into 360° results in the phase shift between the two signals in degrees that is independent of the operating frequency.