Vibration Unit Piezoelectric Element Segmentation Voltage Isolation

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Solution Overview

Problem

Existing vibration units require complex control circuits to prevent high voltage from the drive circuit from flowing into the sensor circuit, complicating the control mechanism due to the voltage difference between the drive and sensor circuits.

Innovation Solution

A vibration unit design featuring a first piezoelectric element for sensing and a second piezoelectric element for driving, with a shared vibration plate and separate external electrodes, allowing the sensor circuit to detect electromotive force and apply drive voltage without the need for additional switching circuits, simplifying the control circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single piezoelectric element is used for both sensing and driving, then device complexity is reduced, but voltage level conflict causes control circuit complexity

Engineering Contradiction:

Improvecontrol circuit complexityVSAvoidvoltage isolation reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The piezoelectric element is divided into two separate elements: a first piezoelectric element for sensing that generates low voltage electromotive force, and a second piezoelectric element for driving that receives high voltage drive signals. This segmentation eliminates voltage level conflict and simplifies control circuit design while maintaining functional reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The vibration unit achieves multi-functionality by using two piezoelectric elements with the same basic structure (piezoelectric body between external electrodes) but different functions: one for sensing pressure input and generating detection signals, and the other for receiving drive signals and generating vibrations. This universal structure with differentiated functions resolves the voltage isolation problem.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If separate switching circuits are added to protect sensor circuit from high voltage, then voltage isolation is ensured, but control circuit complexity increases

Engineering Contradiction:

Improvevoltage isolation reliabilityVSAvoidcontrol circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The harmful high voltage drive signals are extracted and directed to a separate second piezoelectric element, preventing them from entering the sensor circuit. This extraction eliminates the need for protective switching circuits while maintaining voltage isolation reliability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The second piezoelectric element acts as an intermediary that receives high voltage drive signals from the drive circuit and transfers their effect to the vibration plate, preventing direct connection between high voltage and low voltage circuits. This intermediary eliminates the need for complex switching protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If piezoelectric element size is increased to enhance vibration amplitude, then vibration performance improves, but device area increases

Engineering Contradiction:

Improvevibration amplitudeVSAvoiddevice area

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

The second piezoelectric element for driving is designed with larger dimensions than the first piezoelectric element for sensing. This asymmetric design allows the drive element to generate stronger vibrations while the sense element maintains a compact size, optimizing both vibration performance and device area utilization.

Inventive Principle:

Principle #4Asymmetry

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 design simplifies the control circuit by isolating voltage levels, eliminating the need for separate switching circuits and enhancing design flexibility, while increasing vibration amplitude through larger expansion and contraction of the second piezoelectric element.

Implementation Method 1

a sensor circuit that detects an electromotive force occurring due to the flexure of the first piezoelectric element

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a drive circuit that applies a drive voltage to the second piezoelectric element

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11648585B2Vibration unit

Publication Date: 2023.05.16 TDK CORP

AI summary

In a vibration unit, a first electrode of a sensor circuit of a control unit is electrically connected to a first external electrode of a first piezoelectric element, a second electrode of the sensor circuit is electrically connected to a second external electrode of the first piezoelectric element, a first electrode of a drive circuit is electrically connected to a first external electrode of a second piezoelectric element, and a second electrode of the drive circuit is electrically connected to a second external electrode of the second piezoelectric element. Only a relatively small voltage induced by an electromotive force occurring due to the flexure of the first piezoelectric element is applied to the sensor circuit. In addition, only a relatively large drive voltage to be applied to the second piezoelectric element is applied to the drive circuit.