Stepped Piezoelectric Assembly for Sound Directivity

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Solution Overview

Problem

Conventional piezoelectric assemblies in mobile terminals have a large vibration range and broad energy distribution, leading to poor directivity and inefficient space utilization due to uniform ceramic elements, which results in a large internal space occupation and reduced space efficiency.

Innovation Solution

A piezoelectric assembly with a stepped structure formed by stacking piezoelectric layers of varying sizes, where each layer is smaller than the previous one, creating a conical or trapezoidal shape, which concentrates deformation force at the center and reduces the occupied space, enhancing directivity and energy concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If piezoelectric ceramic elements with uniform overall thickness and same cross-sectional area are used, then the actuator has large vibration range and broad energy distribution area, but the signal output has poor directivity and the actuator occupies large internal space

Engineering Contradiction:
Improveoccupied spaceVSAvoiddirectivity
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The piezoelectric ceramic element is segmented into multiple piezoelectric layers with different cross-sectional areas, forming a stepped structure. This segmentation allows different regions to contribute differently to the vibration, concentrating energy at the center while reducing overall volume occupation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from a uniform two-dimensional cross-section to a three-dimensional stepped structure with varying cross-sectional areas at different heights. This dimensional change enables simultaneous achievement of compact volume and centralized energy distribution for improved directivity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If piezoelectric ceramic elements with uniform overall thickness and same cross-sectional area are used, then the actuator has large vibration range, but the space utilization rate of the mobile terminal is reduced

Engineering Contradiction:
Improvespace utilization rateVSAvoidvibration range
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The stepped structure resembles a nested doll configuration where smaller piezoelectric layers are positioned above larger ones, creating a compact vertical arrangement. This nesting approach maximizes space utilization by reducing the horizontal footprint while maintaining the necessary vibration range through the stacked layers.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Quantity of substance

If the overall size of piezoelectric ceramic elements is balanced, then the actuator occupies large internal space, but the energy distribution is broad

Engineering Contradiction:
Improveenergy concentrationVSAvoidinternal space occupation
Core Design Contradiction:
Quantity of substanceVSVolume of stationary object

Solution Approach 1:

The stepped structure implements local quality by concentrating piezoelectric material at the center region with larger cross-sectional area at lower layers, while reducing material quantity at the periphery through smaller cross-sectional areas at upper layers. This creates localized energy concentration where needed while minimizing overall space occupation.

Inventive Principle:
Principle #3Local quality

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 stepped structure design increases deformation force concentration at the center, reduces the occupied space, and improves the directivity of sound output, enhancing user experience and space utilization in mobile terminals.

Implementation Method 1

a piezoelectric assembly includes a vibrating member made of a piezoelectric material and a signal line connected to the vibrating member. The vibrating member includes two or more piezoelectric layers stacked in sequence

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3852159B1Piezoelectric assembly and fabrication method thereof, screen component, and mobile terminal
Publication Date: 2024.05.01 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP3852159B1 patent drawingFigure 1
  • EP3852159B1 patent drawingFigure 2
  • EP3852159B1 patent drawingFigure 3

AI summary

A piezoelectric assembly and a fabrication method thereof, a screen component, and a mobile terminal are provided. The piezoelectric assembly includes a vibrating member (200) made of a piezoelectric material and a signal line (30) connected to the vibrating member. The vibrating member includes two or more piezoelectric layers (10) stacked in sequence. A size of at least one (12) of the piezoelectric layers is smaller than a size of any remaining one (11) of the piezoelectric layers to form a stepped structure.