Ultrasonic Driving Device with Harmonic Decomposition for Stable Vibration

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Solution Overview

Problem

Ultrasonic operation apparatuses face challenges in maintaining stable ultrasonic vibration amplitude due to fluctuating mechanical loads, as existing constant current control methods are inadequate in accurately determining the driving current required for the ultrasonic transducer.

Innovation Solution

The proposed solution involves a driving device with an ultrasonic transducer and an electrical equivalent circuit that includes a second capacitor in parallel with a series circuit of an inductor and a resistor, utilizing an output voltage and current decomposition system to calculate and sum the basic and harmonic components of the driving current, enabling precise constant current control by generating control data for the driving voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If constant current control is performed by fixing the current supplied to the ultrasonic transducer, then stable vibration amplitude is maintained, but the control accuracy deteriorates when mechanical load fluctuates due to inadequate separation of driving current from capacitor current

Engineering Contradiction:

Improvestable vibration amplitudeVSAvoiddriving current determination accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the output current into two distinct components: capacitor current (through the parallel capacitor) and driving current (through the series circuit). By calculating and subtracting the capacitor current component from the total output current, the system accurately isolates the driving current that actually contributes to ultrasonic vibration, thereby maintaining control accuracy under varying mechanical loads.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system continuously monitors the output voltage and current, decomposes them into basic and harmonic components, calculates the capacitor current in real-time, and uses this information to dynamically adjust the driving voltage. This closed-loop feedback mechanism ensures accurate driving current control despite fluctuations in mechanical load conditions.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If the electrical equivalent circuit includes a parallel capacitor, then the ultrasonic transducer model is more accurate, but the current control complexity increases due to the need to separate capacitor current from driving current

Engineering Contradiction:

Improvetransducer model accuracyVSAvoidcurrent control system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex physical current separation hardware with computational analysis. By using mathematical decomposition of output voltage and current into basic and harmonic components, and calculating the capacitor current through circuit analysis, the system achieves accurate driving current determination without requiring additional physical sensors or complex hardware circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system transforms the control approach by changing from direct current measurement to voltage-based calculation. By monitoring output voltage and using the known capacitor characteristics along with the decomposed current components, the system derives the driving current through parameter relationships rather than direct measurement, simplifying the control architecture.

Inventive Principle:

Principle #35Parameter changes

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 allows for accurate control of the driving current, ensuring stable ultrasonic vibration amplitude and effective treatment of living tissues by separating the driving current from the capacitor current, thereby enhancing the precision and reliability of ultrasonic operations.

Implementation Method 1

The ultrasonic transducer includes a piezoelectric element such as a piezoelectric device

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a second capacitor connected in parallel with a series circuit formed of an inductor, a first capacitor, and a resistor

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Data Source

PatentUS10022569B2Driving device and method for controlling the same

Publication Date: 2018.07.17 OLYMPUS CORPORATION(JP)

AI summary

A driving device includes an output voltage decomposing unit which decomposes an output voltage applied to an ultrasonic transducer into a basic and harmonic components; an output current decomposing unit which decomposes an output current flowing through the ultrasonic transducer into a basic and harmonic components; a capacitor current calculator which calculates a basic and harmonic components of a capacitor current, based on the basic and harmonic components of the output voltage; a driving current calculator which calculates a basic and harmonic components of a driving current based on the basic and harmonic components of the output current and the capacitor current, a driving current summing unit which sums up the basic and harmonic components of the driving current, and a constant current controller which generates constant current control data.