Acoustics – Diaphragm and enclosure – With sound-absorbing means
Reexamination Certificate
1999-09-29
2002-01-15
Nappi, Robert E. (Department: 2837)
Acoustics
Diaphragm and enclosure
With sound-absorbing means
C181S199000
Reexamination Certificate
active
06338395
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a loudspeaker enclosure material suitable for enhancing the performance of a loudspeaker and more particularly, the present invention relates to the use of a specific natural material for reducing internal resonance or standing waves as well as loudspeaker resonance.
BACKGROUND OF THE INVENTION
It has been well documented that various acoustic absorbing materials provide use in damping internal distortion within a speaker enclosure as well as enhance the sound quality and efficiency of the speaker system. In instances where standing waves are not damped, the internal reflections produce strong sonic colorations and thus sound quality. A further advantage associated with the use of damping material is that corporation of such material within the enclosure decreases the enclosure frequency resonance and thus produces more sonically desirable bass.
Damping materials which have proved to be suitable for achieving acoustic damping include glasswool, DACRON™, acoustic foam and other synthetic materials. The problem with these materials is that many of them are fairly expensive and can thus add to the manufacturing costs of the loudspeaker unit.
It would be desirable if an acoustic damping material were provided that was inexpensive, achieve the desirable results of damping internal vibration, enhancing bass and enhancing overall performance of the speaker were available. The present invention satisfies this need and provides such a material.
SUMMARY OF THE INVENTION
One object of the present invention is to provide an acoustic damping material which does not suffer from the limitations of the known art.
A further object of one embodiment of the present invention is to provide a sound attenuating material suitable for use in a loudspeaker enclosure, comprising kapok material, the kapok for reducing enclosure resonance and driver resonance.
The use of the kapok material is an alternative material that comes from the seed of kapok trees
“Ceiba pentandra”
. This material is a natural fibrous material and is relatively inexpensive. The kapok material also has a very low density and thus is ideal for acoustic damping. By selection of the appropriate amount of kapok, the result is lower resonance within the enclosure. It has been found that by making use of the kapok that the resonance is greatly reduced relative to other materials. In addition, the kapok is essentially uninfluenced by the heat generated within the enclosure as the speaker drivers are used. This is in marked contrast to synthetic materials, particularly acoustic foam, which inherently would experience property changes due to thermal degradation.
A further object of one embodiment of the present invention is to provide a loudspeaker enclosure having reduced internal resonance, comprising;
a loudspeaker enclosure having a plurality of walls forming an enclosure;
a loudspeaker driver mounted to one of walls; and
kapok material positioned within the enclosure for reducing internal frequency resonance of the enclosure and resonance of loudspeaker.
The kapok has proven particularly successful in closed box systems, vented box systems, passive radiators, transmission line systems and other sub-woofer boxes, such as bandpass enclosures. Excellent results have also been obtained by making use of kapok in television loudspeaker driver enclosures as well as single driver enclosures and multiple driver enclosures.
In accordance with a further object of the present invention, there is provided a method of reducing internal resonance in a loudspeaker enclosure, comprising:
providing a loudspeaker enclosure having a plurality of walls and at least one loudspeaker driver mounted therein;
providing kapok material; and
positioning the kapok material within the enclosure, whereby internal resonance of the enclosure is reduced relative to an enclosure absent the kapok.
Generally speaking, the positioning of the kapok will be in opposition to the wall mounting the loudspeaker driver. This will result in the reduction of standing waves and other intermodular distortions.
Having thus described the invention, reference will now be made to the accompanying drawings illustrating preferred embodiments.
REFERENCES:
patent: 3890474 (1975-06-01), Glicksberg
patent: 4044855 (1977-08-01), Kobayashi
patent: 4101736 (1978-07-01), Czerwinski
patent: 4128738 (1978-12-01), Gallery
patent: 4429762 (1984-02-01), Cesati
patent: 4569414 (1986-02-01), Fulton
patent: 5333204 (1994-07-01), Hamada et al.
patent: 5712038 (1998-01-01), Yamazaki et al.
TPI, Textil Praxis International, Jan./Feb. 1994, p. 68.*
USDA Forest Service, Forest Products Laboratory; Ceiba: Wood Technical Fact Sheet.*
Anguilla Beach Shack, Mary Ann's Tropical Construction Home Page; Ceiba.
Adisusanto
CW Nafis Dwi
Setiabudi J. Dwidjaja
Sutarno
Yusran Setiawan
Birch, Steward, Kolasch & Birch, LLP
Martin Edgardo San
Nappi Robert E.
P.T. Hartono Istana Electronics
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