Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Having acoustic wave modifying structure
Reexamination Certificate
1999-04-06
2003-09-23
Le, Huyen (Department: 2743)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Having acoustic wave modifying structure
C381S345000, C381S352000, C381S182000
Reexamination Certificate
active
06625291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a loudspeaker system, particularly to low cost, high performance loudspeaker enclosures, and more particularly to a diffused resonance loudspeaker system.
2. Description of the Prior Art
Rectangular loudspeaker enclosures constructed from wood, particle board, and plywood are commonly used by both consumers and professionals in the audio industry. A conventional rectangular enclosure having a height X, a width Y, and a depth Z exhibits three internal standing waves at a frequency calculated as f=1100×l, where f is the frequency of the standing wave and l is the dimension of the enclosure (X, Y, or Z) in feet. Thus, the frequency of the three standing waves is determined by the dimension of the enclosure.
In these prior art systems, materials such as fiberglass, foam plastics, long-fiber wool, and synthetic fibers have been used to line the interior of the enclosure in an effort to dampen the standing waves. These prior art systems also typically include internal structures for bracing and supporting the enclosure, but these structures do not provide any significant or effective resonance control.
For example, perimeter braces, which are commonly used, do not adequately deal with these standing waves. Conventional internal matrix structures, which are used in some cases, shift the standing waves to higher frequencies, but still have the significant disadvantage that they alter internal resonance, as defined by the above equation.
Unusually shaped enclosures, such as cylinders, egg-shapes, hedrons, and transmission lines have also been employed in the prior art. However, with the exception of certain egg-shape and straight/tapered transmission lines, these enclosures provide inadequate resonance control. Moreover, the unusually shaped systems which have exhibited adequate resonance control, such as the B & W Nautilus concept and the Waveform egg, have the significant disadvantage that they are extremely costly, and are impractical for low-cost, high performance enclosures.
SUMMARY OF THE INVENTION
Thus a loudspeaker system is needed which is capable of exhibiting excellent resonance control, while being inexpensive to produce and use. Accordingly, the present invention is directed to a loudspeaker system employing an inexpensive enclosure having an internal divider situated to produce diffused resonance control.
The present invention includes a loudspeaker system having at least one loudspeaker drive unit; a loudspeaker enclosure for housing the loudspeaker, the loudspeaker enclosure having a resonating chamber, wherein the loudspeaker drive unit produces at least one standing wave in the resonating chamber; and at least one internal resonance control structure, the internal resonance control structure being positioned within the loudspeaker enclosure to form a tapering cross-sectional area within the resonating chamber in relation to the loudspeaker drive unit to substantially diffuse the standing wave.
The internal resonance control structure of the present invention may include a tapered pyramidal shape having a bottom portion, a tapering midsection, and an apex portion, wherein said apex portion is located proximally to the loudspeaker drive unit. It may also include four tapering pyramidal shapes each having a bottom portion, a tapering, perforated midsection, and an apex, wherein the apex of each of the pyramidal shapes is located proximally to the apex of each of the other pyramidal shapes, or two slotted, perforated dividers, said dividers being configured within the loudspeaker enclosure to produce four tapering pyramidal shapes.
The present invention may also include a second loudspeaker drive unit and a high frequency loudspeaker drive unit, wherein the internal resonance control structure has two perforated dividers and one solid divider, and wherein the two perforated dividers and the solid divider are configured within the resonating chamber such that each of the perforated dividers is parallel to each other and is equidistant across the center of each of the loudspeakers and does not cross the high frequency loudspeaker, and the solid divider is perpendicular to the two perforated dividers across the high frequency loudspeaker and not across the loudspeakers. Similarly, a plurality of loudspeaker drive units serving a plurality of frequency bands can benefit from this method as will be obvious to those skilled in this art.
REFERENCES:
patent: 3912866 (1975-10-01), Fox
patent: 4063387 (1977-12-01), Mitchell
patent: 4200170 (1980-04-01), Williams, Jr.
patent: 5266752 (1993-11-01), Cussans
patent: 6152257 (2000-11-01), Denham
Avaya Technology Corp.
Le Huyen
Volejnicek David
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