Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Mounting or support feature of housed loudspeaker
Reexamination Certificate
2002-07-10
2004-06-01
Ni, Suhan (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Mounting or support feature of housed loudspeaker
C381S345000, C381S349000, C381S350000
Reexamination Certificate
active
06744902
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to enclosures for loudspeakers, and, more particularly, to a ported enclosure for one or more loudspeakers in which sound emanating from opposite ends of the loudspeaker(s) is transmitted to an aperture by a baffle which mounts the loudspeaker(s) in the enclosure and forms a port with the panels of the enclosure. Each of the panels, and at least a portion of the baffle which can be seen through the aperture, are covered with carpeting to provide a finished appearance for mounting in the interior of a vehicle.
BACKGROUND OF THE INVENTION
Audio systems are standard equipment in most vehicles, and they typically include a radio, compact disc player and a number of loudspeakers such as tweeters, mid-range speakers and woofers. The quality of the sound obtained from vehicle audio systems is dependent, in large part, on the loudspeakers which are used in the system. More expensive vehicles tend to be provided with upgraded speakers and more of them, while comparatively inferior speakers are used as standard equipment in other vehicles.
Many individuals, and particularly those with good home audio systems, have come to insist on improved sound quality in their vehicle audio systems so that the music they listen to in a truck or car sounds reasonably close to the way it does at home. This demand has fueled the development of after market audio systems for vehicles in which many of the original components of the vehicle's audio system, and especially the loudspeakers, are replaced with better quality components. Additionally, new components are introduced in many after market systems such as subwoofer loudspeakers which are intended to reproduce low frequency sound thus freeing the woofers and mid-range speakers of the system to reproduce only the higher frequencies for which they are primarily designed.
The addition of subwoofers to vehicle audio systems has improved overall sound quality but also presented some difficulties, particularly in how such speakers are located in the vehicle. Because subwoofers are ordinarily not included as part of original vehicle audio systems, there is usually no location within the vehicle which has been specifically designed by the manufacturer to mount same. As a result, enclosures or cabinets for subwoofers have been developed which for some vehicles have a custom configuration to fit a particular space, and for other vehicles are constructed to mount in the trunk area or the like. In either case, most enclosures for subwoofers have panels whose exterior surfaces are covered with carpeting to provide a durable finish and blend well with the vehicle environment.
One method of fabricating enclosures for subwoofers or other speakers is known as the “wrap” method. It is designed to simplify the attachment of carpeting to the enclosure panels while making it easy to connect the panels to one another. The wrap method generally comprises initially cutting out four side panels, e.g., the top, bottom, front and back sides of the enclosure, and forming beveled edges along the length of each one. The ends of the side panels are also formed with grooves or dados to mount the end panels of the enclosure as described below. The side panels are affixed by glue or the like to a continuous length of carpeting so that their beveled edges are located adjacent to one another. The panels are then “folded” together, with glue introduced along their beveled edges, to form a rectangular shape which is held in place by the carpeting. Before the rectangular shape is closed, the end panels are affixed by glue within the grooves at the ends of the side panels. When the last side panel is folded into place, the two edges that border the carpet ends are glued and nailed together. As such, only one seam is mechanically fastened, while all of the other seams or panel connections are held in place by the glue and carpeting.
Loudspeaker enclosures made with the wrap method or by other techniques sometimes include a “port” or vent consisting of a duct or length of pipe inserted within the enclosure interior which causes the volume of air inside the enclosure to acoustically resonate at a particular frequency. This resonance frequency is determined by the internal volume of the enclosure and the diameter and length of the port. Ports are usually constructed from lengths of plastic pipe, or a duct can be built into the structure of the enclosure itself. The cross sectional area of the port must be chosen to pass sufficient volume of air in and out of the enclosure without creating turbulence which can contaminate the sound output.
In high power applications, larger port cross sections are often needed to pass increased volumes of air. In turn, it is often necessary to increase the length of the port to maintain the same system resonance frequency with a larger port cross section. The overall length of the port is limited by the depth of the enclosure since the inwardly extending end of the port must be spaced from the rear enclosure boundary so that flow is not restricted and the port resonates properly. Consequently, ports are often constructed with a bend in the pipe or a duct built into the enclosure. Both of these alternatives add time, complexity and cost to the enclosure construction.
One particular type of ported loudspeaker enclosure is disclosed in U.S. Pat. No. 5,025,885 to Froeschle. This enclosure is rectangular in cross section having a front wall, back wall, top wall, bottom wall and opposed end walls collectively defining a hollow interior which is divided into front and rear chambers by a partition. The partition mounts a loudspeaker in position to face the front wall, and also mounts a first port tube which extends between the two chambers. A second port tube is mounted in the front wall of the enclosure which extends into the front chamber.
Ported enclosures of the type disclosed in the U.S. Pat. No. 5,025,885 are commonly referred to as “band pass” enclosures because the front chamber and front port, through which all radiation from the loudspeaker must pass, acoustically filter the high frequency output of the system. Such effect occurs since the front port, coupled to the front chamber, resonates at a given frequency thus allowing only certain frequencies to pass from the enclosure into the listening environment. The front port is therefore specifically designed to act as a resonance-tuning device in the frequency range of interest.
Regardless of the method of fabricating a ported loudspeaker, or whether or not it is considered to constitute a band pass enclosure, it is necessary to “dress” or finish the appearance of the inside of the enclosure in the area of the port because one can see directly into the enclosure interior through the port. The appearance of unfinished wood within the enclosure interior is aesthetically unacceptable. Although attempts have been made to cosmetically treat this area, such as with the use of paint or a laminated covering, these solutions add expense and additional time to the enclosure construction.
SUMMARY OF THE INVENTION
It is therefore among the objectives of this invention to provide an enclosure for a loudspeaker which is visually acceptable in the environment of a vehicle, which is economical to fabricate, and which effectively transmits sound produced by loudspeakers mounted therein externally of the enclosure.
These objectives are accomplished in an enclosure for one or more loudspeakers which includes a housing having a top panel, a bottom panel, a front panel, a back panel and opposed end panels collectively defining a hollow interior which is open at an aperture formed in one of the panels. A baffle is mounted within the housing interior which supports one or more loudspeakers to form a port which directs sound radiating from both the front and back of the loudspeaker(s), or only the back of such speaker(s), to the aperture. All of the panels, and the baffle, are covered with carpeting to provide a finished appearance for mounting of the enclosure within the interior of
Holland & Knight LLP
JL Audio, Inc.
Ni Suhan
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