Piezoelectric Sheet Sensor Mounting for Irregular Musical Surfaces

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Solution Overview

Problem

The voltage output from piezoelectric sheet sensors attached to vibrating musical instruments is low due to insufficient adhesion strength caused by surface irregularities on the vibrating body, which hinders effective vibration transmission.

Innovation Solution

A sensor unit is designed with a soft base material having stress conformability interposed between the sheet sensor and the vibrating body, along with a weight, to enhance bonding strength and vibration transmission, increasing the voltage output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a sheet sensor is merely adhered to the surface of the vibrating body, then the device complexity is reduced, but the voltage output becomes low due to insufficient adhesion strength

Engineering Contradiction:
Improvestructure complexityVSAvoidadhesion strength
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

A soft base material is introduced as an intermediary layer between the sheet sensor and the vibrating body. This soft base material conforms to surface irregularities and provides sufficient bonding strength, resolving the contradiction between simple structure and reliable adhesion.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a soft base material is interposed between the sheet sensor and the vibrating body, then the adhesion strength is improved, but the device complexity increases

Engineering Contradiction:
Improvebonding strengthVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The soft base material serves as a mediator that conforms to surface irregularities, ensuring sufficient bonding strength while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The soft base material changes the physical parameters of the bonding interface by conforming to surface irregularities, thereby improving adhesion strength without requiring complex bonding mechanisms.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the surface irregularities are present on the vibrating body, then the manufacturing precision of the vibrating body is maintained, but the vibration transmission to the sensor becomes insufficient

Engineering Contradiction:
Improvesurface irregularitiesVSAvoidvibration transmission
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The soft base material acts as an intermediary that adapts to surface irregularities, ensuring effective vibration transmission while preserving the original surface characteristics of the vibrating body.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The soft base material functions as a flexible layer that conforms to irregular surfaces, enabling effective coupling between the sensor and the vibrating body without requiring precise surface finishing.

Inventive Principle:
Principle #30Flexible shells and thin films

4Reliability

If adhesive layers are provided on both surfaces of the soft base material, then the bonding strength is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvebonding strengthVSAvoidmanufacturing process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The soft base material with adhesive layers on both surfaces serves as a complete bonding intermediary, providing sufficient adhesion to both the sheet sensor and the vibrating body while maintaining ease of assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 ensures sufficient bonding strength and efficient vibration transmission, resulting in higher voltage output from the sheet sensor, even on irregular surfaces, and maintains sensitivity across various vibrational modes and frequencies.

Implementation Method 1

a piezoelectric element (sheet sensor) including electrode layers on both surfaces of a porous resin film is attached to the surface of a vibrating body of a musical instrument. In this configuration, when the vibrating body of the musical instrument vibrates, a voltage corresponding to the vibration of the vibrating body is output from the piezoelectric element (sheet sensor).

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a soft base material having stress conformability is interposed between a sheet sensor and the vibrating body. Therefore, the surface of the soft base material facing the vibrating body conforms to irregularities of the surface of the vibrating body, and as a result, it is possible secure sufficient bonding strength between the sensor unit and the vibrating body. Thereby, it is possible to increase the voltage that is output from the sheet sensor.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3480568B1Sensor unit and musical instrument
Publication Date: 2021.12.08 YAMAHA CORP
  • EP3480568B1 patent drawingFigure 1~2
  • EP3480568B1 patent drawingFigure 3~4

AI summary

A sensor unit is for attaching to a vibrating body. The sensor unit includes: a sheet sensor that has a sheet shape and flexibility. The sheet sensor converts vibration that acts in a thickness direction of the sheet sensor to a voltage and outputting the voltage. The sensor unit further includes a first sticking member that includes a soft base material and two adhesive layers. The soft base material has a sheet shape and stress conformability. The two adhesive layers are respectively provided on both surfaces of the soft base material. The first sticking member is attached to one surface of the sheet sensor.