Coaxial MF-HF Loudspeaker Assembly for Wavefront Alignment
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Solution Overview
Problem
Existing loudspeaker systems face challenges in reproducing the wide range of human auditory perception due to bandwidth limitations and interference patterns between low, mid, and high-frequency drivers, particularly in large-scale systems, leading to inefficient and unstable mid-frequency driver performance.
Innovation Solution
A loudspeaker assembly with a coaxial configuration of a mid-frequency (MF) driver and a high-frequency (HF) driver, utilizing a phase plug and waveguide design that ensures sufficient acoustic pathlength and minimizes interference by using a semi-ovoid or semi-elliptical capsule and strategically positioned slots to align wavefronts, allowing for improved impedance matching and extended bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a two-way loudspeaker system combines LF and HF drivers, then the system can reproduce a wide frequency range, but the bandwidth limitations and interference patterns between drivers cause instability and inefficiency in mid-frequency reproduction
Solution Approach 1:
The patent divides the frequency spectrum into three distinct bands (LF: 40-200 Hz, MF: 200-6000 Hz, HF: 6000-20000 Hz) and assigns separate optimized drivers to each band. This segmentation allows each driver to operate within its optimal frequency range, eliminating the bandwidth limitations and interference patterns that plague two-way systems while ensuring stable and efficient mid-frequency reproduction.
2Device complexity
If MF drivers are derived from LF driver concepts, then the driver structure is simpler, but the efficiency and upper band response are poor due to diaphragm stiffness and mass limitations
Solution Approach 1:
The patent applies local quality by giving each driver band-specific optimizations tailored to its frequency range. The MF driver features a lightweight dome diaphragm with specific stiffness characteristics optimized for mid-frequency response, rather than using a generic LF-style cone structure. This localized optimization ensures high efficiency and excellent upper band response while maintaining appropriate structural simplicity.
3Reliability
If MF drivers are derived from HF driver concepts, then the upper frequency response is improved, but the low frequency performance is limited due to diaphragm fragility and displacement limitations
Solution Approach 1:
The patent changes key parameters of the MF driver design, specifically using a dome-shaped diaphragm with optimized stiffness-to-mass ratio that differs from both LF cone drivers and HF tweeters. The diaphragm material and structural parameters are specifically tuned to handle mid-frequency ranges, providing both the fragility resistance needed for low-frequency operation and the stiffness required for high-frequency response.
4Volume of moving object
If horns and drivers are closely spaced to reduce size, then the system compactness is improved, but destructive interference increases in severity as frequency increases due to convex diverging wavefronts
Solution Approach 1:
The patent introduces phase plugs as intermediary components between the drivers and the horn array. These phase plugs serve as mediators that condition the acoustic wavefronts before they enter the horn system, transforming convex diverging wavefronts into more uniform patterns. This intermediary element allows closely spaced horns and drivers to operate together without severe destructive interference, maintaining both compactness and acoustic coherence.
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 configuration enhances mid-frequency reproduction by reducing interference and instability, achieving improved efficiency and coherence across the mid-frequency range, suitable for large-scale applications.
Implementation Method 1
a phase plug disposed between the first driver diaphragm and the second driver, the phase plug positioned within the phase plug outer housing, and defining at least one slot for providing air movement (acoustic coupling) between the first driver diaphragm and the curved passageway
Implementation Method 2
utilizing a phase plug and waveguide design that ensures sufficient acoustic pathlength and minimizes interference by using a semi-ovoid or semi-elliptical capsule and strategically positioned slots to align wavefronts
Implementation Method 3
a curved passageway is formed around the capsule within a duct
Data Source
Figure 1
Figure 1A
Figure 2A~2B
AI summary
A loudspeaker assembly having a waveguide, comprising: a housing comprising an outer duct and a phase plug housing; a first driver comprising a diaphragm; a second driver coaxially disposed in front of the first driver diaphragm and comprising a capsule having a rear surface, wherein a curved passageway is formed around the capsule within a duct; and a phase plug disposed between the first driver diaphragm and the second driver, the phase plug positioned within the phase plug outer housing, and defining at least one slot having an inlet for providing air movement between the first driver diaphragm and the curved passageway; wherein the rear surface of the capsule forms part of the phase plug, and a uniform gap is defined between the first driver diaphragm and the rear surface of the capsule, and wherein the first driver is a lower frequency driver than the second driver.