Abstract:
The speaker assembly includes a speaker housing having a closed top wall and an opposed open end. The speaker assembly further includes a first sound source having a cone with an interior surface and an exterior surface. The first sound source is mounted within the speaker housing such that the interior surface of the cone faces the closed top wall and the exterior surface substantially faces the opposed open end. A portion of the exterior surface of the cone is covered, thereby, revealing an exposed portion which defines the directionality of the first sound source. The speaker assembly also includes a second sound source having a cone with an interior surface and an exterior surface. The second sound source is mounted within the speaker housing such that the interior surface of the cone faces the closed top wall and the exterior surface substantially faces the opposed open end. A portion of the exterior surface of the cone is covered, thereby, revealing an exposed portion which defines the directionality of the second sound source. The exposed portion of the first sound source faces a direction opposite the exposed portion of the second sound source to create stereo separation between the first and second sound sources.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a speaker assembly. More particularly, the invention relates to a speaker assembly with reduced size and weight to enhance the performance of the speaker assembly within aircraft. 
     2. Description of the Prior Art 
     The current global community has made it possible for people from around the country, and around the world, to interact for both business and personal reasons. For many people, this requires that they spend considerable time traveling from one location to another location. More often than not, these people travel in aircraft. 
     Whether these people travel in private or commercial aircraft, they desire high quality entertainment during the many hours they spend within the confines of an aircraft. However, while high quality entertainment, for example, digital video with CD quality sound, is readily available for theater and home use, the weight and size requirements for use in aircraft makes it very difficult to incorporate high fidelity systems within an aircraft. This problem is especially pronounced for audio speaker assemblies when one attempts to meet the size, weight and shape requirements for use in aircraft. 
     In the aircraft industry great priority is placed upon component weight and size reduction. Range and payload are adversely affected by conventional terrestrial designs. These concerns are notable when one attempts to make changes within smaller private jets. For example, a small increase in the weight carried by an aircraft results in a substantial increase in the fuel consumption of the aircraft. In addition, the limited space available within an aircraft dictates that the use of any space within the aircraft be carefully considered by those responsible for ensuring the comfort of passengers. 
     Lightweight and compact audio speakers are currently available. These speakers, however, substantially compromise sound quality for reductions in size and weight. An individual wishing to add an audio system to an aircraft must make a choice between high fidelity speakers which do not suit the size and weight requirements of the aircraft and lower quality speakers providing desirable size and weight characteristics. 
     A need, therefore, exists for a speaker assembly providing a high fidelity sound, while also meeting the size and weight requirements of an aircraft. The present invention provides such a speaker assembly. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a speaker assembly including a speaker housing having a closed top wall and an opposed open end. The speaker assembly further includes a first sound source having a cone with an interior surface and an exterior surface. The first sound source is mounted within the speaker housing such that the interior surface of the cone faces the closed top wall and the exterior surface substantially faces the opposed open end. A portion of the exterior surface of the cone is covered, thereby, revealing an exposed portion which defines the directionality of the first sound source. The speaker assembly also includes a second sound source having a cone with an interior surface and an exterior surface. The second sound source is mounted within the speaker housing such that the interior surface of the cone faces the closed top wall and the exterior surface substantially faces the opposed open end. A portion of the exterior surface of the cone is covered, thereby, revealing an exposed portion which defines the directionality of the second sound source. The exposed portion of the first sound source faces a direction opposite the exposed portion of the second sound source to create stereo separation between the first and second sound sources. 
     It is also an object of the present invention to provide a speaker wherein foam covers the exterior surface of the first sound source and foam covers the exterior surface of the second sound source. 
     It is another object of the present invention to provide a speaker wherein the exposed portion of the first sound source amounts to a segment of approximately 25% to approximately 40% of the exterior surface of the first sound source and the exposed portion of the second sound source amounts to a segment of approximately 25% to approximately 40% of the exterior surface of the second sound source. 
     It is a further object of the present invention to provide a speaker wherein the first and second sound sources are midrange drivers. 
     It is also an object of the present invention to provide a speaker including a first tweeter positioned adjacent the first sound source and a second tweeter positioned adjacent the second sound source. The first tweeter and the second tweeter are outwardly mounted in opposition to generate a stereo image. 
     It is still another object of the present invention to provide a speaker wherein the first tweeter is mounted between approximately a 25° angle and approximately a 75° angle relative to the opposed open end of the speaker housing and the second tweeter is mounted between approximately a 25° angle and approximately a 75° angle relative to the opposed open end of the speaker housing. 
     It is yet a further object of the present invention to provide a speaker including a public address driver. 
     It is also an object of the present invention to provide a speaker wherein the cone of the first sound source directly engages the closed top wall to define an enclosed spaced bounded by the closed top wall and the interior surface of the cone and the cone of the second sound source directly engages the closed top wall to define an enclosed spaced bounded by the closed top wall and the interior surface of the cone. 
     It is still another object of the present invention to provide a speaker wherein a first clamp secures the first sound source to the closed top wall and a second clamp secures the second sound source to the closed top wall. 
     It is also an object of the present invention to provide a speaker assembly wherein the first sound source is mounted within the speaker housing such that the interior surface of the cone faces the closed top wall and the exterior surface substantially faces the opposed open end. A gasket is positioned between the edge of the cone and the closed top wall of the speaker housing. The gasket traps air between the interior surface of the cone and the closed top wall to enhance the performance of the sound source, such that the enclosed space defined by the interior surface of the cone and the closed top wall is substantially free of the gasket and the closed top wall, the depth of the gasket, and interior surface of the cone define the enclosed space. 
     It is another object of the present invention to provide a speaker wherein the gasket includes an interior edge which substantially follows the edge of the cone. 
     It is still a further object of the present invention to provide a speaker wherein the gasket is foam secured to the top closed wall upon which the edge of the cone is mounted. 
     It is also an object of the present invention to provide a speaker wherein the foam includes an interior edge which substantially follows the edge of the cone, and the closed top wall, the depth of the foam, and interior surface of the cone define the enclosed space. 
     It is another object of the present invention to provide a speaker wherein the foam covers all of the closed top wall with the exception of the enclosed space. 
     It is also an object of the present invention to provide a speaker assembly including a first sound source covered to alter the resonant characteristics of the first sound source, a second sound source covered to alter the resonant characteristics of the first sound source, a first tweeter positioned adjacent the first sound source and a second tweeter positioned adjacent the second sound source. The first tweeter and the second tweeter are outwardly mounted in opposition to generate a stereo image. The frequency response altered by covering the first sound source and the second sound source create a physical crossover network. 
     It is another object of the present invention to provide a speaker wherein a portion of the first sound source is covered thereby revealing an exposed portion which defines the directionality of the first sound source and a portion of the second sound source is covered thereby revealing an exposed portion which defines the directionality of the first sound source. 
     It is a further object of the present invention to provide a speaker wherein foam covers the first sound source and foam covers the second source. 
     Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cut away perspective view of the present speaker assembly. 
     FIG. 2 is a top view of the present speaker assembly. 
     FIG. 3 is a cross sectional view along the line  3 — 3  in FIG.  2 . 
     FIG. 4 is a cross sectional view of an alternate embodiment in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The detailed embodiment of the present invention is disclosed herein. It should be understood, however, that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limited, but merely as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. 
     With reference to FIGS. 1-3, a low profile speaker assembly  10  is disclosed. The speaker assembly  10  incorporates a variety of features which reduce the size and weight of the speaker assembly  10 , without compromising the integrity of the sound generated by the speaker assembly  10 . The speaker assembly  10  is primarily intended for use in aircraft, where weight and size are critical. The speaker assembly  10  is designed to extend longitudinally within the center of the cabin. While the speaker assembly  10  is preferably designed for use in aircraft, the speaker assembly may be used in a variety of environments, such as wall enclosed room speakers, automotive speakers or within personal computers, without departing from the spirit of the present invention. 
     The speaker assembly  10  includes a speaker housing  12  with a closed top wall  14  and an opposed open end  16 . The closed top wall  14  forms a support surface upon which the active speaker components are mounted. The speaker housing  12  is preferably constructed from aluminum, although other materials may be employed without departing from the spirit of the present invention. 
     In accordance with the preferred embodiment of the present invention, the closed top wall  14  is substantially rectangular, although other shapes may be employed without departing from the spirit of the present invention. Four corner mounts  18  extend upwardly from the respective corners of the closed top wall  14 . Each corner mount  18  includes an inwardly directed bracket  20  with apertures  22  adapted for attaching the speaker assembly  10  within the fuselage of an aircraft. The brackets  20  are respectively mounted to a slot  21  formed in each corner mount  18  via screwing such that the position of each bracket may be adjusted to facilitate proper installation. 
     The corner mounts  18  attach to a mounting bracket  24  of the aircraft. The mounting bracket  24  is adapted to facilitate the installation of the present speaker assembly  10  within an aircraft fuselage. 
     For reasons that will be better appreciate based upon the following disclosure, the sides  26  of the speaker assembly  10  adjacent the active components remain open. The open spaces reduce the weight of the speaker assembly  10 , while also reducing sound cancellation to improve the sound quality of the present speaker assembly  10 . 
     The active components of the speaker assembly  10  include first and second midrange drivers  28 ,  30 , first and second high frequency drivers (i.e., tweeters)  32 ,  34  and a public address driver  36 . The active components are mounted within the speaker housing  12  such that the first midrange driver  28  and the first tweeter  32  are mirror images of the second midrange driver  30  and the second tweeter  34 . As will be discussed in greater detail below, and with the exception of the public address driver  36 , the components are wired to produce stereo sound; that is, the first midrange  28  and tweeter  32  are wired to receive a left channel signal, while the second midrange  30  and tweeter  34  are wired to receive a right channel signal (not shown). The public address driver  36  is distinct from the other active components, and is designed for the transmission of announcement messages commonly issued from the flight crew. While the preferred embodiment is disclosed as providing stereo sound, it is contemplated that the arrangement of components could be varied without departing from the spirit of the present invention. 
     A sheet of foam insulation  38  (FAA approved for burn test) is secured to the closed top wall  14  of the speaker housing  12  between the active components and the closed top wall  14  of the speaker housing  12 . The public address driver  36  is a conventional midrange driver with a cone  40  and is mounted substantially at the center of the speaker housing  12 . The cone  40  includes an interior surface  42  which is directed toward the closed top wall  14 . In this way, sound emitted from the exterior surface  44  of the public address driver  36  is directed through the opposed open end  16 . 
     The sound generated by the public address driver  36  is enhanced by removing foam insulation  38  from within the space defined by the meeting point of the edge  46  of the public address driver cone  40  and the closed top wall  14 . In fact, the foam  38  is cut away such that the foam insulation  38  forms a gasket about the edge  46  of the public address driver cone  40 , sealing the space defined between the interior surface  42  of the cone  40  and the top closed wall  14 . 
     The gasket traps air between the interior surface  42  of the cone  40  and the closed top wall  14  to enhance the performance of the public address driver  36 , such that the enclosed space defined by the interior surface  42  of the cone  40  and the closed top wall  14  is substantially free of the foam insulation  38 . In practice, the depth of the foam insulation  38 , the closed top wall  14  and the interior surface  42  of the cone  40  define the enclosed space. 
     The first midrange driver  28  and first tweeter  32  are mounted along a first side  48  of the closed top wall  14 . The first midrange driver  28  is connected to the closed top wall  14  of the speaker housing  12  such that the interior surface  50  of the cone  52  of first midrange driver  28  faces the closed top wall  14  of the speaker housing  12 . The exterior edge  54  of the cone  52  is directly attached to the closed top wall  14  to seal off the space defined by the interior surface  50  of the cone  52  of the first midrange driver  28 . The cone  52  is held in contact with the closed top wall  14  by a first clamp  56  wrapped about the first midrange driver  28  and then bolted to the closed top wall  14 . A piece of foam insulation  39  is preferably positioned between the first clamp  56  and the first midrange driver  28  to prevent rattling which may occur between the first clamp  56  and the first midrange driver  28 . While a clamp is used to mount the first midrange driver  28  to the closed top wall  14 , those skilled in the art will appreciate the fact that other attachment techniques may be employed without departing from the spirit of the present invention. 
     As will be discussed in greater detail below, the first tweeter  32  is mounted adjacent the first midrange driver  28 . The first tweeter  32  is mounted such that it faces away from the closed top wall  14 . The first tweeter  32  is also positioned in an opposed relationship with the second tweeter  34  to enhance the stereo separation produced by the present speaker assembly  10 . 
     As with the first midrange driver  28  and tweeter  32 , the second midrange driver  30  and second tweeter  34  are mounted along a second side  58  of the closed top wall  14 . The second midrange driver  30  is connected to the closed top wall  14  of the speaker housing  12  such that the interior surface  60  of the cone  62  of second midrange driver  30  faces the closed top wall  14 . The exterior edge  64  of the cone  62  is directly attached to the closed top wall  14  to seal off the space defined by the interior surface  60  of the cone  62  of the second midrange driver  30 . The second midrange driver  30  is coupled thereto by a second clamp  66  in the same manner as discussed above with regard to the first midrange driver  28 . 
     The second tweeter  34  is mounted adjacent the second midrange driver  30 . As was discussed above, the second tweeter  34  is mounted to face away from the closed top wall  14  and the first tweeter  32 . In fact, the second tweeter  34  is positioned in an opposed relationship with the first tweeter  32  to enhance the stereo separation produced by the present speaker assembly  10 . 
     The first tweeter  32  and the second tweeter  34  are respectively mounted on opposites sides of the speaker housing  12 , producing a true stereo image with minimal “footprint” (that is, a true stereo image is produced with the use of minimal space). The minimal space needed is facilitated by inverting the first and second midrange drivers  28 ,  30 . Inversion of the first and second midrange drivers  28 ,  30  creates the extra space adjacent the open end  16  of the speaker housing  12  needed for mounting the first and second tweeters  32 ,  34  in an opposed relationship. 
     As stated above, the first tweeter  32  receives a left channel of a stereo signal and the second tweeter  34  receives a right channel of a stereo signal. Although the first and second tweeters  32 ,  34  are closely mounted within a single speaker housing  12 , a stereo image is produced by outwardly mounting the tweeters in opposition. Specifically, the tweeters are mounted between approximately a 25° angle and a 75° angle relative to the plane of the opposed open end  16 , and preferably at approximately a 45° angle relative to the plane of the opposed open end  16 . In addition, the lateral orientation of the tweeters may be varied, although the preferred embodiment employs a lateral orientation of 45° relative to a plane extending from the first long side  68  of the speaker housing  12  to the second long side  70  of the speaker housing  12 . 
     The stereo separation produced by the present speaker assembly  10  is further enhanced by the provision of foam wrap  72  provided about a substantial portion of the cone exterior of the midranges. Specifically, foam wrap  72  is secured about a substantial portion of the first midrange driver  28  with a preselected portion  73  of the cone exterior  74  remaining exposed. The exposed portion  73  amounts to a segment of between approximately 25% and 40% of the entire cone circumference. The exact extent of the exposed portion  73  is determined based upon the resonant frequency, as well as other characteristics, of the midrange driver employed, such that the performance of the present speaker assembly  10  is optimized. In accordance with the preferred embodiment of the present invention, the exposed portion  73  faces substantially away from the exposed portion  78  of second midrange driver  30  (see below) to enhance the stereo separation produced by the present speaker assembly  10 . 
     Foam wrap  76  is similarly secured about a substantial portion of the second midrange driver  30  with a preselected portion  78  of the cone exterior  80  remaining exposed. As with the first midrange driver  28 , the exposed portion  78  amounts to a segment of between approximately 25% to 40% of the entire cone circumference. In accordance with the preferred embodiment of the present invention, the exposed portion  78  faces substantially away from the exposed portion  73  of first midrange driver  28 . In fact, the exposed portions  73 ,  78  are respectively aligned with the first and second tweeters  32 ,  34  to enhance the stereo separation produced by the present speaker assembly  10 . 
     In accordance with the preferred embodiment of the present invention, the foam wrap is ⅛″ black Safelite™ foam applied to the cone exterior surface  74 ,  80  with adhesive. While foam wrap is used to improve the directional characteristics of the midrange drivers employed in accordance with the present invention, other techniques may be used without departing from the spirit of the present invention. For example, it is contemplated that the clamps discussed above may be formed to completely cover the drivers with the exception of a port formed in the clamp. The port would permit the control of emitted sound in much the same manner the foam wrap controls the emitted sound. Similarly, a combination of metal and foam may be used to controlled the sound emitted by the exterior surface of the first and second midrange drivers. 
     In use, sound from the first midrange driver  28  is primarily radiated from the exposed portion  73  and directed away from the exposed portion  78  of the second midrange driver  30 . Similarly, the first tweeter  32  directs sound in a predetermined direction away from the second tweeter  34 . 
     The directionality produced by the first and second midrange drivers  28 ,  30  and the first and second tweeters  32 ,  34  generates distinct and desirable stereo separation from a single compact speaker assembly  10 . In addition, the design of the inverted first and second midrange drivers  28 ,  30  enhances the sound quality of the speaker assembly  10 , while also reducing the size and weight of the speaker assembly  10 . Specifically, the foam wraps  72 ,  76  improve the directionality of the midrange drivers  28 ,  30 . The sound ultimately heard from the midrange drivers  28 ,  30  by an individual is substantially the sound radiating from the cone exteriors  74 ,  80  of the midrange drivers  28 ,  30 . 
     The inclusion of the foam wrap  72 ,  76  about the cone exteriors  74 ,  80  of the midrange drivers  28 ,  30  also functions to improve the frequency response of the sound emitted from the exterior surfaces of the cones. Specifically, the foam wrap  72 ,  76  limits the passage of specific frequencies, while permitting other frequencies from passing therethrough. The foam wrap  72 ,  76  also improves phase cancellation and resonant characteristics associated with the midrange drivers  28 ,  30 . In this way, the foam wrap  72 ,  76  functions as a physical crossover and obviates the need for the use of a traditional crossover network. The removal of a traditional electronic crossover network from the present speaker assembly results in a dramatic weight and size reduction. Specifically, speaker assemblies in accordance with the present invention have been manufactured with a weight as little as 1 lb. 1 oz. In addition to reducing the weight of the present speaker assembly, the physical crossover network simplifies the design and manufacture, while also reducing cost. 
     In addition to creating a speaker assembly  10  with improved directionality, the inverted positioning of the first and second midrange drivers  28 ,  30  allows more proximate positioning of the tweeters  32 ,  34  in both the vertical and horizontal planes. The ability to position the tweeters  32 ,  34  more proximate reduces the size and weight of the entire speaker assembly  10 . The proximate positioning of the tweeters  32 ,  34  and midrange drivers  28 ,  30  provides additional space within the speaker housing  12  to enable an installer to access the speaker housing  12  and bolt the speaker assembly to the headliner of the aircraft. 
     Installation of the speaker assembly is completed by mounting the speaker assembly  10  at a desired location such that the opposed open end  16  of the speaker assembly  10  is directed toward the listening environment and the closed top wall  14  of the speaker housing  12  is directed away from the listening environment. Once the speaker assembly  10  is properly mounted, an expanded metal/perforated speaker grill  82  is placed over the opposed open end  16  of the speaker assembly  10  to hide the contents of the speaker assembly  10  and protect the acoustic components found within the speaker housing  12 . The speaker grill  82  is secured to the mounting bracket  24  by a hook and loop fastening  84 , although the speaker grill  82  may be secured to the speaker housing  12  in a variety of manners without departing from the spirit of the present invention. In addition, the speaker grill  82  may be secured on the speaker housing  12  prior to installing the speaker assembly  10  at a desired location. The speaker grill  82  should be designed such that it limits interference with sound generated by the tweeters  32 ,  34  to ensure a high quality stereo sound field. 
     The embodiment disclosed in FIGS. 1,  2  and  3  is designed for placement in the space within an aircraft designed for an oxygen box, and is 4.2″ wide, 8.25″ long, and 1.5″ deep. The speaker assembly  10  also weighs only 1 lb. 9 oz. and has a radius of curvature of shaped to conform with the space in which it must fit. 
     While the speaker assembly  10  disclosed in FIGS. 1 to  3 , employs pairs of tweeters and midrange drivers to produce a stereo image, speaker assemblies  110  including only the public address driver  136  are considered to fall within the spirit of the present invention. Specifically, and with reference to FIG. 4, a speaker assembly  110  with only the disclosed public address driver  136  is mounted within a speaker housing  112  substantially as discussed above. The speaker assembly  110  may then be installed. If, at a later date, the owner of the aircraft wishes to retrofit the aircraft with stereo sound, the public address driver only speakers may simply be replaced with the stereo speaker assemblies discussed above. 
     By employing simple public address speaker assemblies  110  in accordance with the present invention, substantial weight savings are achieved. Specifically, by employing the open speaker housing  112  of the present invention and removing a small portion of foam, a substantial weight savings (approximately 2 lbs.) is achieved when one considers the many public address speakers which would be employed in a conventional aircraft. 
     While the preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.