Non-Lead Piezoelectric Vibrator With Split Resonance Modes

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Solution Overview

Problem

Existing ultrasonic motors face challenges in replacing lead-based piezoelectric ceramics with non-lead-based alternatives, resulting in reduced motor speed and increased power consumption due to differences in density and Young's modulus.

Innovation Solution

A vibrator design incorporating a non-lead-based piezoelectric ceramic with a Pb component content less than 1000 ppm, where the resonance frequencies of two vibration modes satisfy a specific frequency difference, allowing for efficient vibration wave generation and low power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If non-lead-based piezoelectric ceramic is used to replace lead-based piezoelectric ceramic, then environmental impact is reduced, but motor speed decreases and power consumption increases

Engineering Contradiction:

Improveenvironmental impactVSAvoidmotor speed

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The patent changes the physical parameters of the vibrator, specifically the resonance frequencies of the two vibration modes. By setting the absolute difference between the resonance frequencies to greater than 2 kHz, the vibrator compensates for the performance degradation caused by using non-lead-based piezoelectric ceramic, thereby restoring motor speed and reducing power consumption while maintaining environmental benefits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite approach by combining non-lead-based piezoelectric ceramic with a specifically designed vibrator structure that incorporates two vibration modes with controlled frequency separation. This composite solution integrates material substitution with structural optimization to achieve both environmental compliance and performance requirements

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If non-lead-based piezoelectric ceramic is used to replace lead-based piezoelectric ceramic, then environmental impact is reduced, but power consumption increases

Engineering Contradiction:

Improveenvironmental impactVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent modifies the operational parameters of the vibrator by establishing a specific frequency separation condition (absolute difference greater than 2 kHz) between the two vibration modes. This parameter change optimizes the vibration wave generation efficiency, allowing the motor to operate with lower power consumption despite using non-lead-based piezoelectric ceramic

Inventive Principle:

Principle #35Parameter changes

3Productivity

If resonance frequency difference between two vibration modes is increased, then vibration wave generation efficiency is improved, but device complexity increases

Engineering Contradiction:

Improvevibration wave generation efficiencyVSAvoiddevice complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs dynamic vibration modes that can be excited independently, allowing flexible control of the two vibration modes. This dynamic approach enables the system to achieve high vibration wave generation efficiency through frequency separation while maintaining relatively simple device structure by utilizing the inherent dynamic characteristics of the vibrator

Inventive Principle:

Principle #15Dynamics

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

Enables high-speed operation with low power consumption in ultrasonic motors using non-lead-based piezoelectric ceramics, addressing the limitations of previous designs by optimizing vibration mode intersection and displacement control.

Implementation Method 1

a piezoelectric element including a piezoelectric material and electrodes

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a resonance frequency fA in a vibration mode A and a resonance frequency fB in a vibration mode B satisfy a relation of an absolute value of (fB−fA)>2 (kHz)

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11831254B2Vibrator, vibration wave drive device, vibration wave motor, and electronical device

Publication Date: 2023.11.28 CANON KK

AI summary

The present invention provides a vibrator made of a non-lead-based piezoelectric material and capable of being driven at a sufficient speed with low power consumption, and provides a vibration wave drive device and an electronical device each using the vibrator. To that end, the vibrator according to the present invention includes a piezoelectric element including a piezoelectric material and electrodes, and an elastic body, wherein a Pb component contained in the piezoelectric material is less than 1000 ppm, and a resonance frequency fA in a vibration mode A and a resonance frequency fB in a vibration mode B satisfy a relation of an absolute value of (fB−fA)>2 (kHz), the vibration mode A and the vibration mode B generating vibration waves in the elastic body with wave fronts of the vibration waves intersecting each other.