Vibration Actuator Structure for Symmetric Lead-Free Piezo Motion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vibration-type actuators using lead-free piezoelectric ceramics experience temperature distribution and in-plane distribution of piezoelectric properties, leading to inequivalent vibration characteristics in forward and reverse directions.
Innovation Solution
A vibration-type actuator design with a rectangular-shaped elastic body and piezoelectric element, featuring protruding portions with space portions and specific area ratios, and a manufacturing method involving controlled bonding and polarization temperatures to ensure uniform piezoelectric properties and symmetric vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free piezoelectric ceramics are used to reduce environmental impact, then the harmful factors to the environment are reduced, but temperature distribution and in-plane distribution of piezoelectric properties occur during polarization treatment, leading to inequivalent vibration characteristics in forward and reverse directions
Solution Approach 1:
The elastic body is designed with asymmetric protruding portions that create different thermal mass distributions. This asymmetric structure compensates for the inherent temperature distribution during polarization treatment, ensuring that the piezoelectric properties remain uniform across the element plane, thereby achieving equivalent vibration characteristics in both forward and reverse directions while maintaining lead-free environmental benefits
Solution Approach 2:
The invention optimizes the geometric parameters of the elastic body, specifically the area ratio of protruding portions (S2/S1 < 0.178), to control heat distribution during polarization treatment. By carefully selecting these parameters, the temperature distribution is minimized, ensuring uniform piezoelectric properties and symmetric vibration characteristics without requiring lead-based materials
2Reliability
If the elastic body structure is optimized to improve vibration symmetry, then the round-trip speed difference is reduced, but the device complexity increases due to specific geometric constraints
Solution Approach 1:
The elastic body features localized protruding portions with specific geometric properties (area ratio S2/S1 < 0.178) that are strategically positioned to address temperature distribution issues. This local optimization approach improves vibration symmetry without requiring complete redesign of the entire device structure, thereby limiting the increase in device complexity to only the critical geometric parameters of the protruding portions
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 actuator achieves reduced round-trip speed difference and improved vibration symmetry, ensuring equivalent vibration characteristics in both directions with minimal lead content, thus reducing environmental impact.
Implementation Method 1
a vibration body configured such that, when an alternating voltage is applied to an electro-mechanical energy conversion element such as a piezoelectric element, a vibration is excited in an elastic body joined to the piezoelectric element
Implementation Method 2
heating piezoelectric ceramics to perform polarization treatment
Data Source
AI summary
A vibration-type actuator in which the content of lead included in a piezoelectric material is 1000 ppm or less has an elastic body that includes a protruding portion and a flat portion. The protruding portion includes a top portion that contacts a contact body. The protruding portion is provided with a space portion therein, and includes an outer surface and an inner surface. The top portion is arranged at a position crossing a nodal line of out-of-plane vibration of the elastic body in plan view. A value obtained by dividing a total area of a portion surrounded by the outer surface when a base portion of the protruding portion is viewed in cross-section in a direction parallel to the flat portion by a product of a length of a short side and a length of a long side of a principal surface of the piezoelectric element is smaller than 0.178.