Dipole Loudspeaker Unit for Personal Sound Cocoon
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Solution Overview
Problem
Current loudspeaker systems in vehicles fail to effectively create a personal sound cocoon for individual passengers, particularly at bass frequencies, due to the impracticality of traditional monopole loudspeakers and the need for large radiating surfaces, which leads to sound leakage and inadequate sound pressure levels.
Innovation Solution
A seat assembly with a loudspeaker unit featuring a diaphragm having opposite radiating surfaces that are out of phase, allowing sound to propagate through sound guides positioned remotely from the radiating surfaces, enabling effective sound localization and reduced leakage by using a dipole or multipole configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional monopole loudspeakers are used for bass frequencies, then sound pressure level can be increased, but sound leakage increases and personal sound cocoon effectiveness deteriorates
Solution Approach 1:
The patent applies the inversion principle by using a dipole loudspeaker configuration where the radiating surfaces face opposite directions and move in opposite phases. Instead of having sound radiate in one direction from a monopole, the dipole configuration has front and back radiating surfaces that move oppositely, creating destructive interference in the far field and confining bass energy to the near field personal sound cocoon region.
Solution Approach 2:
The patent changes the fundamental parameter of loudspeaker radiation pattern from monopole (spherical radiation in all directions) to dipole (figure-eight radiation pattern with opposite phase surfaces). This parameter change transforms the sound propagation characteristics, creating regions of constructive and destructive interference that enable personal sound cocoon formation with reduced sound leakage.
2Adaptability or versatility
If highly directive loudspeakers are positioned close to individual passengers for medium and high frequencies, then personal sound cocoon effectiveness is improved, but the solution becomes impractical for bass frequencies due to wavelength constraints
Solution Approach 1:
The patent uses the dipole configuration with oppositely phased radiating surfaces to achieve bass frequency directionality without requiring large radiating surfaces. The inversion of phase between front and back surfaces creates the necessary directional control for personal sound cocoon formation, making the solution practical for vehicle installations where space is limited.
3Power
If loudspeakers are placed very close to individual passengers to achieve adequate sound pressure level, then personal sound cocoon is created, but sound leakage to other passengers increases
Solution Approach 1:
The patent converts the normally harmful effect of sound radiation into a beneficial phenomenon by using destructive interference. The oppositely phased radiating surfaces create regions of sound cancellation in directions away from the listener, transforming what would normally be sound leakage into sound suppression, thereby protecting other passengers from unwanted bass frequencies.
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 provides an effective personal sound cocoon with improved sound pressure levels at bass frequencies, reducing sound leakage and enhancing the listening experience for individual passengers while maintaining design flexibility.
Implementation Method 1
a drive unit configured to move the diaphragm based on an electrical signal
Implementation Method 2
the loudspeaker unit is configured to allow sound produced by the first and second radiating surfaces to propagate out from the loudspeaker unit
Implementation Method 3
a sound guide configured to guide sound produced by the first or second radiating surface to at least one outlet such that the sound propagates out of the loudspeaker unit from the at least one outlet
Data Source
Figure 1(a)~1(b)
Figure 1(c)~1(d)
Figure 1(e)~1(f)
AI summary
A loudspeaker unit for producing sound at bass frequencies. The loudspeaker unit includes: a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating and second radiating surfaces are located on opposite faces of the diaphragm, and wherein the loudspeaker unit is configured to allow sound produced by the first and second radiating surfaces to propagate out from the loudspeaker unit; a drive unit configured to move the diaphragm based on an electrical signal; a frame from which the diaphragm is suspended via one or more suspension elements; drive circuitry configured to provide the drive unit with an electrical signal derived from an audio source; a sound guide configured to guide sound produced by the first or second radiating surface to at least one outlet such that the sound propagates out of the loudspeaker unit from the at least one outlet, the/each outlet being remote from said first or second radiating surface. The loudspeaker unit is preferably configured so that, at the locations at which sound propagates out from the loudspeaker, and preferably in the operational bandwidth of the loudspeaker unit, the sound produced by the/each first radiating surface is substantially out of phase with the sound produced by the/each second radiating surface.