Piezoelectric Speaker Port Positioning for High-Pitch Sound Pressure
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Solution Overview
Problem
Acoustic devices such as earphones and headphones face challenges in improving sound quality, particularly in enhancing the electroacoustic conversion function of piezoelectric sound-generating elements and achieving higher sound pressure in the high-pitch range when used with dynamic speakers.
Innovation Solution
An electroacoustic transducer design that includes a piezoelectric speaker with a vibration plate and multiple openings, where the sound introduction port is positioned to not overlap the largest opening, and a support member with a Young's modulus of 3 GPa or more is used to stabilize the vibration plate and improve resonance, allowing for enhanced sound pressure characteristics in the high-pitch range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sound introduction port is positioned to overlap with the largest opening of the piezoelectric speaker, then the structure is simpler and easier to manufacture, but the sound pressure characteristics in the high-pitch range deteriorate
Solution Approach 1:
The patent resolves the contradiction by transitioning from a two-dimensional overlap problem to a three-dimensional spatial arrangement. The sound introduction port is positioned in the planar view to overlap with the largest opening, but the diaphragm is tilted at a specific angle relative to the housing bottom surface. This angular arrangement creates a three-dimensional spatial relationship where the sound introduction port and the largest opening do not actually overlap in the acoustic path, thereby improving sound pressure characteristics while maintaining manufacturing simplicity.
2Reliability
If the diaphragm is tilted at a large angle relative to the housing bottom surface, then the sound pressure in the high-pitch range is improved, but the stability of the piezoelectric speaker deteriorates
Solution Approach 1:
The patent applies parameter optimization by specifying that the diaphragm is tilted at a specific angle range (5 degrees to 15 degrees) relative to the housing bottom surface. This controlled parameter change achieves the dual benefit of improving high-pitch sound pressure while maintaining the stability of the piezoelectric speaker. The angle is large enough to improve acoustic performance but small enough to prevent excessive instability.
Solution Approach 2:
The patent employs a composite structure where the piezoelectric speaker is integrated with the housing in a specific configuration. The diaphragm is supported by a support structure that combines rigid and flexible elements, creating a composite system that maintains stability even with the tilted arrangement. This composite construction allows the diaphragm to be angled for improved high-pitch performance while the support structure ensures overall stability.
3Reliability
If multiple openings are provided around the piezoelectric element, then the electroacoustic conversion function is improved, but the device complexity increases
Solution Approach 1:
The patent divides the acoustic structure into multiple segments by providing multiple openings (at least three) around the piezoelectric element. Each opening serves as an independent acoustic pathway, allowing sound waves to escape from different locations on the diaphragm. This segmentation improves the electroacoustic conversion function by enhancing sound radiation efficiency while distributing the acoustic load across multiple openings rather than requiring a single large complex structure.
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 design improves sound pressure characteristics and achieves higher sound pressure levels in the high-pitch range, resulting in clearer sound quality and improved acoustic performance.
Implementation Method 1
a piezoelectric element placed on at least one face of the first vibration plate
Data Source
AI summary
An electroacoustic transducer includes a piezoelectric speaker and a housing. The piezoelectric speaker has: a first vibration plate with a periphery; a piezoelectric element placed on at least one face of the first vibration plate; and multiple openings that are provided around the piezoelectric element and penetrate through the first vibration plate in its thickness direction that is a first axis direction. The housing has: a supporting part that directly or indirectly supports the periphery; and a sound introduction port that faces the piezoelectric speaker in the first axis direction. The sound introduction port is provided at a position where it does not overlap, in the first axis direction, a first opening having the largest open area among the multiple openings. The electroacoustic transducer can improve the acoustic characteristics of a piezoelectric speaker.