Front Port Resonator for Micro Speaker Quarter Wave Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Micro speakers in consumer electronics face challenges in maximizing sound output due to size constraints, leading to limited frequency bandwidth and poor sound quality, particularly due to the quarter wave resonance phenomenon where sound waves become out of phase and diminish in loudness at specific frequencies.
Innovation Solution
A resonator is acoustically coupled to the front port of the micro speaker, tuned to resonate at the same frequency as the quarter wave resonance of the acoustic pathway, extending the frequency bandwidth without altering the driver components, and positioned to optimize sound wave energy distribution across frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sound radiating surface is positioned away from the cosmetic opening due to size constraints, then the device can maintain a compact form factor, but the acoustic pathway length increases causing quarter wave resonance that diminishes sound quality
Solution Approach 1:
A resonator is introduced as an intermediary acoustic component between the sound radiating surface and the cosmetic opening. The resonator includes a cavity and a neck positioned at a specific distance from the opening, acting as a mediator to compensate for the phase shift caused by the acoustic pathway, thereby maintaining sound quality despite the increased distance between the diaphragm and opening
Solution Approach 2:
The resonator's cavity volume and neck dimensions are specifically designed and tuned to resonate at the quarter wave frequency of the acoustic pathway. By adjusting these physical parameters, the resonator generates an acoustic signal that counteracts the phase shift, effectively changing the acoustic characteristics of the system to compensate for the extended pathway length
2Shape
If the acoustic pathway length is increased to accommodate cosmetic requirements, then the device achieves a more compact appearance, but the frequency bandwidth is limited due to quarter wave resonance effects
Solution Approach 1:
The resonator serves as an intermediary acoustic element that extends the effective frequency response. By positioning the resonator's neck at a specific distance from the cosmetic opening and tuning its cavity volume, it generates acoustic energy at frequencies that would otherwise be diminished by the quarter wave resonance, thereby expanding the usable frequency bandwidth
Solution Approach 2:
The resonator exploits acoustic vibration and resonance principles by designing a cavity that resonates at specific frequencies. This vibration-based mechanism generates acoustic pressure variations that complement the direct sound from the diaphragm, effectively extending the frequency bandwidth without requiring changes to the driver components
3Ease of manufacture
If resonator components are added to extend frequency bandwidth, then sound quality is improved, but the device complexity increases
Solution Approach 1:
The resonator is designed to perform multiple acoustic functions simultaneously: it compensates for quarter wave resonance effects, extends the frequency bandwidth, and maintains sound pressure levels across a wider frequency range. This multi-functionality allows a single component to address multiple sound quality issues without proportionally increasing device complexity
Solution Approach 2:
The resonator cavity is positioned within or adjacent to the existing speaker enclosure structure, utilizing available space efficiently. The resonator's components are integrated into the compact device architecture, nesting the additional acoustic element within the existing form factor constraints rather than adding external bulk
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 enhances sound quality by maintaining consistent sound pressure levels across a wider frequency range, improving human perception of sound quality and addressing the limitations of micro speakers in compact devices.
Implementation Method 1
The resonator may be tuned to resonate at a same frequency as a quarter wave resonance of the front volume chamber such that it extends a frequency bandwidth of a sound generated by the sound radiating surface
Implementation Method 2
every open-ended air channel, or a tube, has a fundamental frequency or quarter wavelength that is linked to the length of the channel or tube. This length may be the length at which only a quarter of the wavelength can occur in that length of tube
Implementation Method 3
at resonance, the phase shifts by 180 degrees. A 180 degree phase shift means the sound waves traveling inside the acoustic channel are out of phase with the speaker, therefore after this resonance, the loudness of the speaker diminishes significantly
Data Source
AI summary
A micro-speaker assembly including an enclosure having an enclosure wall separating a surrounding environment from an encased space, wherein the enclosure wall defines an acoustic port from the encased space to the surrounding environment; a sound radiating surface positioned within the encased space and dividing the encased space into a front volume chamber and a back volume chamber, wherein the front volume chamber is acoustically coupled to a first surface of the sound radiating surface and the acoustic port, and the back volume chamber acoustically coupled to a second surface of the sound radiating surface; and a resonator acoustically coupled to the front volume chamber, wherein the resonator comprises a neck acoustically coupled to an acoustic cavity, and an opening to the neck is positioned at a distance from the acoustic port that corresponds to a quarter wavelength resonance of the front volume chamber.