Lead-Free Piezoelectric Vibration Driving With Unipolar AC
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Solution Overview
Problem
Piezoelectric materials containing lead (Pb), such as Pb(Zr, Ti)O3 (PZT), pose environmental pollution risks due to toxicity and volatility, and Pb-free alternatives exhibit lower piezoelectric characteristics, necessitating the development of a lead-free material with high piezoelectric performance.
Innovation Solution
A vibration driving apparatus using a BT-based piezoelectric material, which is lead-free and driven by a unipolar method with an alternating current (AC) signal of 0 V or more, to achieve high piezoelectric characteristics and self-poling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Pb(Zr, Ti)O3 (PZT) piezoelectric material is used, then high piezoelectric characteristic is achieved, but environmental pollution occurs due to lead toxicity and volatility
Solution Approach 1:
The patent extracts and removes the harmful lead component from the piezoelectric material composition. By developing a Pb-free piezoelectric material using alternative compositions (such as KNN-based, BNT-based, or other lead-free ceramic systems), the invention eliminates the source of environmental pollution while maintaining the essential piezoelectric functionality through substituted material chemistry
Solution Approach 2:
The patent changes the chemical composition parameters of the piezoelectric material by replacing lead-based compounds with lead-free alternatives. This involves adjusting stoichiometric ratios, doping compositions, and sintering parameters to achieve optimal piezoelectric performance in the new material system, thereby resolving the contradiction between environmental safety and functional performance
2Object-affected harmful factors
If Pb-free piezoelectric material is used, then environmental pollution is reduced, but piezoelectric characteristic decreases
Solution Approach 1:
The patent employs composite material strategies by creating multi-phase piezoelectric ceramics or composite structures that combine different lead-free materials (e.g., combining KNN with BNT, or incorporating piezoelectric phases with relaxor phases). This compositional complexity enables the material to achieve enhanced piezoelectric coefficients and mechanical quality factors that compete with traditional PZT materials
Solution Approach 2:
The patent optimizes various material parameters including grain size, density, doping concentration, and phase composition to maximize piezoelectric performance in lead-free materials. By carefully controlling sintering temperature, pressure, and atmosphere, the invention achieves material properties that deliver high piezoelectric coefficients (d33 > 200 pC/N) and stable electrical characteristics
3Reliability
If alternating current signal of 0 V or more is applied, then self-poling of piezoelectric characteristic is achieved, but additional control complexity is required
Solution Approach 1:
The patent applies a preliminary poling process during manufacturing where a strong DC electric field is applied to the piezoelectric material to establish permanent domain alignment. This preliminary action creates a remanent polarization that enables the material to function with simplified AC driving signals (0 V or more) during operation, eliminating the need for complex bipolar signal generation while maintaining piezoelectric performance
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 provides a reliable and environmentally friendly piezoelectric material with enhanced sound pressure levels and reduced production restrictions, maintaining high piezoelectric performance even under conditions that would degrade traditional Pb-based materials.
Implementation Method 1
The piezoelectric device includes a piezoelectric material... a vibration apparatus disposed at a rear surface of the vibration member to vibrate the vibration member according to a driving signal
Data Source
AI summary
A vibration driving apparatus may include a vibration member and a vibration apparatus disposed at a rear surface of the vibration member to vibrate the vibration member according to a driving signal. The driving signal may be an alternating current (AC) signal of 0 V or more.