Sound Generator Shell Extension for Compact Rear Cavity
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Solution Overview
Problem
Existing sound generating devices face challenges in miniaturization while maintaining good low-frequency performance and acoustic quality due to the need for larger rear cavities, which increases space occupation and can lead to irregular airflow and polarization issues.
Innovation Solution
A sound generator design with a shell structure that extends downward to form a large, regular rear cavity below the vibration and magnetic circuit systems, incorporating a metal sheet for magnetic leakage shielding, and using a breathable spacer with sound absorbing material to enhance acoustic performance without increasing horizontal space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a larger rear cavity is formed to improve low-frequency performance, then low-frequency resonance frequency is reduced and acoustic quality is improved, but space occupation in horizontal direction increases which is not conducive to miniaturization
Solution Approach 1:
The patent changes the spatial arrangement by extending the shell downward in the vertical dimension to create the rear cavity, rather than expanding horizontally. This allows the rear cavity to be formed between the second portion of the shell, the bottom surface of the magnetic circuit system, and the shell bottom wall or lower cover plate, achieving sufficient cavity volume without increasing horizontal footprint.
2Volume of moving object
If the volume of the sound generating device is reduced for miniaturization, then space occupation is reduced, but the volume of the rear cavity is bound to be reduced which affects acoustic performance
Solution Approach 1:
The patent extends the shell downward to create sufficient rear cavity volume within a compact horizontal footprint. The first portion of the shell corresponds to the vibration system and magnetic circuit system, while the second portion extends beyond the bottom surface of the magnetic circuit system to form the rear cavity vertically, maintaining acoustic performance while achieving miniaturization.
Solution Approach 2:
The patent nests the rear cavity within the vertical space created by extending the shell downward, utilizing the space between the magnetic circuit system and the shell bottom wall or lower cover plate. This nested arrangement allows the rear cavity to be integrated into the overall device structure without adding external volume.
3Volume of stationary object
If the rear cavity is formed with irregular shape to maximize volume, then rear cavity volume is maximized, but airflow from the sound generator into the rear cavity is not stable which causes polarization and distortion
Solution Approach 1:
The patent applies different structural characteristics to different parts of the shell. The first portion of the shell has a shape corresponding to the vibration system and magnetic circuit system, while the second portion extends downward in a regular manner to form the rear cavity. This localized differentiation allows the rear cavity to have sufficient volume while maintaining regular geometry for stable airflow.
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 achieves miniaturization while maintaining acoustic performance by creating a sufficient rear cavity space without additional box structures, simplifying manufacturing, and improving airflow stability for better sound quality.
Implementation Method 1
a metal sheet for shielding magnetic leakage being provided on the side wall of the shell
Implementation Method 2
using a breathable spacer with sound absorbing material to enhance acoustic performance
Data Source
AI summary
A sound generator comprises a shell, a vibration system and a magnetic circuit system sequentially accommodated and fixed at a first end of the shell from top to bottom; the magnetic circuit system is provided with a rear sound hole; the shell comprises a first portion corresponding to the vibration system and the magnetic circuit system, and a second portion integrally extending downward from the first portion beyond a bottom surface of the magnetic circuit system. A second end portion of the shell is integrally provided with a shell bottom wall or separately mounted with a lower cover plate; and a rear cavity in communication with the rear sound hole is formed.