Piezoelectric Vibration Control Using Impedance-Based Frequency Tracking

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Solution Overview

Problem

Vibration devices with piezoelectric elements face challenges in maintaining appropriate driving frequencies due to changes in resonant frequencies caused by factors like temperature fluctuations and foreign matter, leading to inefficient cleaning of light-transmitting bodies in imaging units, and existing solutions increase manufacturing costs and processor complexity.

Innovation Solution

A control device that adjusts the clock width of drive signals to match the impedance of piezoelectric elements, determining the driving frequency based on measured impedance values, allowing for precise control of the driving frequency without requiring costly processor upgrades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the resonant frequency of the piezoelectric element is changed due to temperature fluctuations or foreign matter, then the driving frequency control becomes inaccurate, but increasing processor complexity or upgrading processors can resolve this issue

Engineering Contradiction:

Improvedriving frequency control accuracyVSAvoidprocessor complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control device measures the impedance of the piezoelectric element and uses this feedback to determine and adjust the driving frequency. This closed-loop feedback mechanism allows the system to adapt to frequency changes caused by temperature or foreign matter without requiring complex processor upgrades.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces complex processor-based frequency control with a simpler impedance measurement and determination system. By substituting the mechanical/electronic complexity of processor adjustments with a direct impedance-based control method, the system achieves accurate frequency control with reduced complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If the resonant frequency changes due to foreign matter or temperature, then the cleaning efficiency of light-transmitting bodies decreases, but implementing frequency adjustment mechanisms increases manufacturing costs

Engineering Contradiction:

Improvecleaning efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The control device automatically measures the impedance and determines the appropriate driving frequency without requiring external intervention or complex adjustment mechanisms. This self-service capability maintains cleaning efficiency while avoiding the need for expensive manual or automated frequency adjustment hardware.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system changes the driving frequency parameter based on measured impedance values, allowing the piezoelectric element to operate at optimal frequencies under varying conditions. This parameter adaptation maintains cleaning efficiency without requiring physical modifications or expensive adjustment mechanisms.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a constant alternating current is maintained through the piezoelectric element, then the resonant frequency control is improved, but the device complexity and manufacturing cost increase

Engineering Contradiction:

Improveresonant frequency controlVSAvoidcontrol circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex constant current control circuits with a simpler impedance measurement and frequency determination system. By substituting the complex electrical control mechanism with a direct impedance-based approach, the system achieves reliable resonant frequency control with reduced circuit complexity and manufacturing cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method effectively controls the driving frequency of piezoelectric elements, ensuring efficient cleaning of light-transmitting bodies while reducing manufacturing costs and simplifying processor requirements.

Implementation Method 1

a piezoelectric element provided in or on a vibration device... an alternating current flowing through the piezoelectric element... driving frequency for driving the piezoelectric element

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

measuring a value related to an impedance of the piezoelectric element, and determining a driving frequency for driving the piezoelectric element based on the measured value related to the impedance

Methodology Applied

Scientific EffectImpedance measurement: Electrical Resistance

Data Source

PatentUS20240421727A1Control device that controls vibration device, and method of controlling vibration device

Publication Date: 2024.12.19 MURATA MFG CO LTD

AI summary

The present disclosure relates to a method of controlling a vibration device including a piezoelectric element via a control device. The method includes changing a frequency of a drive signal for driving the piezoelectric element, measuring a value related to an impedance of the piezoelectric element, and determining a driving frequency for driving the piezoelectric element based on a change in the measured value related to the impedance of the piezoelectric element. The changing of the frequency of the drive signal includes changing a clock width such that a clock width of a first portion of clocks among a plurality of clocks included in the drive signal and a clock width of a second portion of clocks among a plurality of clocks are different from each other.