Dual Compression Driver Annular Exit for HF Directivity Control
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Solution Overview
Problem
Existing dual compression drivers with circular exits face issues with high-frequency directivity control due to cross-modes and unnecessary acoustic path redundancy, especially in line arrays where circular entrances and rectangular exits create unwanted spherical wavefronts.
Innovation Solution
A dual compression driver design featuring an annular exit is achieved by merging acoustic signals from two driver assemblies through radial channels in phasing plugs, which then radiate outwardly to an annular pathway, using an extension duct and waveguide to control directivity and minimize path lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a circular exit is used in dual compression drivers, then the driver structure is simpler and easier to manufacture, but high-frequency directivity control deteriorates due to cross-modes and spherical wavefront formation
Solution Approach 1:
The patent applies asymmetry by transitioning from a symmetric circular exit to an asymmetric configuration where the waveguide entrance is circular but the exit is rectangular with vertical dimension significantly larger than horizontal dimension. This asymmetric shape prevents cross-modes and spherical wavefront formation while maintaining manufacturing feasibility through standardized rectangular geometries.
Solution Approach 2:
The patent introduces dimensional change by transforming the circular cross-section into a rectangular cross-section with emphasized vertical dimension. This dimensional transformation creates a rectangular exit where the vertical dimension is significantly larger than the horizontal dimension, enabling cylindrical wavefront formation and improving high-frequency directivity control without compromising manufacturing ease.
2Object-affected harmful factors
If the waveguide entrance is circular and exit is rectangular, then cylindrical wavefront is achieved for line arrays, but the acoustic path becomes more complex and longer
Solution Approach 1:
The patent applies preliminary action by implementing progressive time delay of sound waves toward the middle of the vertically-oriented rectangular exit. This pre-planned time delay arrangement ensures that sound waves arrive simultaneously along the vertical profile, creating a flat wavefront and cylindrical wave pattern without requiring excessive path lengthening.
Solution Approach 2:
The patent applies dynamics by creating a vertically-oriented rectangular exit where the acoustic path is dynamically optimized. The waveguide structure allows sound waves to travel different path lengths to different regions of the rectangular exit, with the vertical dimension being significantly larger, enabling flexible wavefront shaping while controlling overall path length through geometric optimization.
3Quantity of substance
If larger exit diameter is used in waveguides, then more acoustic energy is radiated, but high-frequency directivity control worsens due to cross-modes
Solution Approach 1:
The patent applies asymmetry by using a rectangular exit with vertical dimension significantly larger than horizontal dimension instead of a circular exit. This asymmetric geometry increases the effective radiating area and acoustic energy output while simultaneously preventing cross-modes and maintaining superior high-frequency directivity control through the non-circular cross-section.
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 configuration enhances high-frequency directivity control and reduces acoustic path redundancy, providing improved sound pressure level and dynamic range while maintaining a cylindrical wavefront suitable for line arrays.
Implementation Method 1
a first motor assembly having a first internal disc magnet disposed about a central axis at a first end of the dual compression driver
Implementation Method 2
acoustic signals from the first plurality of apertures merge with acoustic signals from the second plurality of apertures between the output side of the first phasing plug and the output side of the second phasing plug
Implementation Method 3
radiate radially outward to the annular pathway and through the annular exit
Implementation Method 4
an extension duct having a bottom end mounted to the first phasing plug and a top end extending toward the second end of the dual compression driver
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A dual compression driver includes first driver assembly and a second driver assembly each including a motor assembly disposed about a central axis and a phasing plug coaxial to each motor assembly, wherein each motor assembly includes an internal disc magnet. Each phasing plug includes an input side oriented toward the motor assembly, an output side oriented away from the motor assembly, and a plurality of apertures extending therethrough. An extension duct has a bottom end mounted to the phasing plug of the first driver assembly, wherein an inner surface of the extension duct and an outer surface of the second driver assembly form an annular pathway terminating at an annular exit of the dual compression driver. Acoustic signals from the first and second driver assemblies merge between the output sides of the phasing plugs and radiate radially outward to the annular pathway and through the annular exit.