Waveguide Integrating Acoustic Low-Pass Filter for Loudspeaker

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Solution Overview

Problem

Existing loudspeaker systems face challenges in reducing size while maintaining performance, as multiple speakers require complex and costly crossover networks, and there is a need for efficient use of limited space without compromising sound distribution.

Innovation Solution

A waveguide that functions as both a high-frequency sound waveguide and an acoustic low-pass filter for low-frequency sound drivers, featuring an outer surface to direct sound waves and an inner surface with openings to overlay the acoustical radiating surface of a second sound source, reducing the need for complex crossover networks by allowing low frequencies to pass through.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple speakers are used to cover different frequency ranges, then sound quality across full audible spectrum is improved, but device complexity and space requirements increase

Engineering Contradiction:

Improvesound qualityVSAvoidcrossover network complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The waveguide is designed to perform multiple functions: it acts as a high-frequency sound waveguide for the tweeter while simultaneously functioning as an acoustical low-pass filter for the low-frequency sound driver. This multi-functionality eliminates the need for separate crossover networks, reducing device complexity while maintaining full frequency range coverage

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the waveguide structure and low-pass filter function into a single integrated component. The waveguide's physical structure (openings, chambers, and pathways) serves dual purposes: directing high-frequency sound and filtering low-frequency sound, thereby merging what would traditionally require separate components

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple speakers are used to cover different frequency ranges, then sound quality across full audible spectrum is improved, but the size of the loudspeaker package increases

Engineering Contradiction:

Improvesound qualityVSAvoidloudspeaker package size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The waveguide serves dual functions as both a high-frequency sound distribution structure and a low-frequency acoustic filter, eliminating the need for separate crossover network components and reducing the overall volume required for the loudspeaker package

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

By integrating the low-pass filter function into the waveguide structure itself, the patent reduces the number of separate components needed, thereby reducing the overall package size while maintaining full frequency range capability

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If traditional crossover networks are used to separate frequency ranges, then frequency separation is achieved, but cost and space requirements increase

Engineering Contradiction:

Improvefrequency separationVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the electrical crossover network (mechanical/electrical system) with an acoustical low-pass filter based on the waveguide's physical structure. The filter operates through acoustic principles (sound wave interaction with openings and chambers) rather than electrical components, simplifying manufacturing and reducing cost

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts the low-pass filter function from the traditional electrical crossover network and implements it through the waveguide's acoustical structure, eliminating the need for expensive electronic components and complex circuit boards

Inventive Principle:

Principle #2Taking out (Extraction)

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 solution enables compact loudspeaker systems to generate sound across the full audible frequency range with minimal frontal surface area, reducing design complexity and cost by eliminating the need for separate crossover networks, while maintaining focused sound coverage.

Implementation Method 1

an outer surface shaped to direct sound waves radiated from a first sound source positioned at an opening in the waveguide

Methodology Applied

Scientific EffectSound wave propagation: Sound

Implementation Method 2

The openings configured to enable the waveguide to function as an acoustical low pass filter for sound radiated through the openings from a second sound source

Methodology Applied

Scientific EffectAcoustical filtering: Acoustic Absorption

Data Source

PatentUS8130994B2Waveguide

Publication Date: 2012.03.06 HARMAN INT IND INC

AI summary

A waveguide configured to function as a high frequency waveguide for a high frequency sound source mounted to the waveguide, and to function as an acoustical low pass filter for a low frequency sound source mounted behind the waveguide in a multi-way loudspeaker system. The waveguide includes openings that overlay the vibrating surface of the low frequency source. The openings are configured by selection of various geometrical parameters to tailor filtering characteristics as desired.