Piezoelectric Speaker With Segmented Stiffness Diaphragm
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Solution Overview
Problem
Piezoelectric speaker arrays face challenges in reproducing bass-range sounds effectively due to miniaturization, leading to deterioration in sound quality and interference between frequency bands, particularly in audio-visual applications where wide sound range reproduction is necessary.
Innovation Solution
A piezoelectric speaker design featuring a substrate with distinct regions of varying bending stiffness and frequency band-specific piezoelectric elements, allowing for independent vibration control and reduced interference between treble and bass-range sound reproduction regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If piezoelectric speakers are miniaturized to control directivity in speaker arrays, then directivity control is improved, but bass-range sound reproduction deteriorates
Solution Approach 1:
The diaphragm is divided into multiple independent vibration regions (first through fifth electrode portions) with different areas and bending stiffnesses. This segmentation allows each region to be optimized for specific frequency ranges, enabling miniaturized speakers to reproduce bass sounds effectively while maintaining directivity control capability.
Solution Approach 2:
Different regions of the diaphragm are designed with different bending stiffnesses and areas to match specific frequency requirements. The first electrode portion has larger area and lower bending stiffness for bass reproduction, while the fifth electrode portion has smaller area and higher bending stiffness for high-frequency reproduction. This local differentiation resolves the contradiction between miniaturization and bass reproduction.
2Reliability
If multiple piezoelectric speakers are arranged at narrow intervals to secure sound quality at multiple listening positions, then sound quality at multiple positions is improved, but speaker size must be reduced
Solution Approach 1:
Each speaker is segmented into multiple vibration regions that can be independently controlled, allowing the speaker to function as multiple sound sources simultaneously. This enables effective directivity control and multi-position sound quality without requiring physically larger speaker arrays.
Solution Approach 2:
The multi-region diaphragm structure allows a single miniaturized speaker to perform multiple functions: bass reproduction, mid-range reproduction, high-frequency reproduction, and directivity control. This multi-functionality compensates for the reduced speaker size while maintaining sound quality at multiple listening positions.
3Device complexity
If a single diaphragm is used in miniaturized piezoelectric speakers, then device complexity is reduced, but interference between frequency bands occurs
Solution Approach 1:
The single diaphragm is designed with locally differentiated properties - different regions have different bending stiffnesses and areas optimized for specific frequency bands. This local quality differentiation prevents frequency band interference while maintaining the simplicity of a single diaphragm structure.
Solution Approach 2:
The diaphragm regions are designed with different dynamic characteristics (bending stiffness, area) that allow them to vibrate independently at different frequencies. This dynamic differentiation enables frequency band separation without requiring physically separate diaphragms, thus maintaining structural simplicity while preventing interference.
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 enhances sound quality by enabling wide-range sound reproduction in limited spaces while maintaining directivity control, reducing interference and improving bass-range sound reproduction limits.
Implementation Method 1
a first piezoelectric element which is mounted on the first region and to which a voltage of a first frequency band is applied, and a second piezoelectric element which is mounted on the second region and to which a voltage of a second frequency band different from the first frequency band is applied
Data Source
AI summary
A piezoelectric speaker is a piezoelectric speaker which radiates acoustic waves by vibrating according to an applied voltage, including (i) a substrate which includes a first region having first bending stiffness against bending of a plane perpendicular to a vibration direction and a second region having second bending stiffness against bending of the perpendicular plane, the second bending stiffness being different from the first bending stiffness, (ii) a first piezoelectric element which is mounted on the first region and to which a voltage of a first frequency band is applied, and (iii) a second piezoelectric element which is mounted on the second region and to which a voltage of a second frequency band different from the first frequency band is applied.