Piezoelectric Vibration Module With Silicone Rubber Plate

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Solution Overview

Problem

Piezoelectric acoustic modules face challenges with temperature-dependent resonance frequency due to materials like polyurethane, which harden at low temperatures and soften at high temperatures, leading to poor water-tightness and complex wiring connections that restrict vibration characteristics.

Innovation Solution

A piezoelectric vibration module with a silicone rubber elastic plate and a housing member, featuring a laminate structure with alternately layered piezoelectric and electrode components, and a flexible wiring board for simplified electrical connections, ensuring impact resistance and stable temperature characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polyurethane is used as the molding material for water-tightness, then ease of manufacture is improved, but temperature characteristics deteriorate due to hardening at low temperature and softening at high temperature

Engineering Contradiction:

Improvemolding processVSAvoidtemperature characteristics

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent changes the material parameter from polyurethane to silicone rubber, which has different thermal properties. Silicone rubber maintains its flexibility across a wider temperature range, preventing the hardening at low temperature and softening at high temperature that occurs with polyurethane, thereby improving temperature characteristics while maintaining ease of molding

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure combining silicone rubber with a resin coating layer. The silicone rubber provides water-tightness and temperature stability, while the resin coating enhances protection and maintains structural integrity, creating a composite material system that resolves the contradiction between ease of manufacture and temperature stability

Inventive Principle:

Principle #40Composite materials

2Productivity

If heating is used to cure silicone rubber solution, then curing speed is improved, but polarization of the bimorph element is lost due to high curing temperature

Engineering Contradiction:

Improvecuring speedVSAvoidpolarization retention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the curing parameter from thermal curing to moisture curing. This allows the silicone rubber to cure at room temperature or lower temperatures, preventing the loss of polarization that occurs at high temperatures (70-250°C), while still achieving complete curing through the moisture-curing mechanism

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal curing mechanism with a moisture-curing chemical mechanism. Instead of using heat to activate the curing process, the silicone rubber composition cures through reaction with moisture in the air, substituting a thermal process with a chemical process that occurs at lower temperatures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If complex wiring connections are provided for electrode layers, then electrical connection reliability is improved, but device complexity increases and vibration characteristics are restricted

Engineering Contradiction:

Improveelectrical connectionVSAvoidwiring structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the wiring function into the molding material itself. The silicone rubber contains conductive fillers or conductive particles that create electrical pathways, combining the structural support and electrical connection functions into a single integrated component, thereby reducing device complexity while maintaining connection reliability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The silicone rubber molding material serves multiple functions simultaneously: it provides water-tightness, mechanical support, electrical insulation or conduction (depending on composition), and vibration transmission. This multi-functionality eliminates the need for separate complex wiring structures, reducing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 module achieves improved temperature stability, enhanced vibration displacement, and simplified mounting with increased sound pressure and flattened frequency characteristics, while avoiding resonance issues with the mounting member.

Implementation Method 1

A piezoelectric acoustic module such as a piezoelectric speaker for use in a mobile telephone or the like is intended for sound amplification

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

an elastic plate attached to one surface of the piezoelectric element, wherein the elastic plate is made of a silicone rubber

Methodology Applied

Scientific EffectViscoelastic damping: Viscoelasticity

Data Source

PatentUS9544694B2Piezoelectric element, piezoelectric vibration module, and methods of manufacturing the same

Publication Date: 2017.01.10 TOKIN CORP

AI summary

A piezoelectric vibration module includes a piezoelectric element, a wiring member connected to the piezoelectric element and drawn out to the outside, and an elastic plate bonded to one surface of the piezoelectric element, wherein the elastic plate is made of a silicone rubber.