Patent Publication Number: US-10771874-B2

Title: Speaker system such as a sound bar assembly having improved sound quality

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/191,556, filed Nov. 15, 2018, (which is scheduled to issue as U.S. Pat. No. 10,499,130 on Dec. 3, 2019), which is a continuation of U.S. patent application Ser. No. 15/910,110, filed Mar. 2, 2018 (U.S. Pat. No. 10,142,716), which is a continuation of U.S. patent application Ser. No. 15/267,401, filed Sep. 16, 2016 (U.S. Pat. No. 9,913,014), which is a continuation of U.S. patent application Ser. No. 13/852,130, filed Mar. 28, 2013 (U.S. Pat. No. 9,462,385), the disclosures of which are hereby incorporated in their entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     This invention generally relates to sound or speaker systems and, in particular, to sound or speaker systems such as sound bar assemblies having a plurality of speaker units. 
     OVERVIEW 
     Speaker systems or devices configured to transmit audible sound are known to be constructed in various configurations. All speaker devices have some form of transducing device typically mounted in a chassis or enclosure. 
     One role of the enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open driver from interacting with sound waves generated at the front of the driver. Because the forward- and rearward-generated sounds are out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced. Additionally, because they travel different paths through the listening space, the sound waves arrive at the listener&#39;s position at slightly different times, introducing echo and reverberation effects not part of the original sound. 
     The enclosure also plays a role in managing vibration induced by the driver frame and moving airmass. 
     Speaker systems are also known to include multiple speakers some of which are selected to broadcast in particular frequency ranges. That is, it is known that audible sound occurs primarily in a frequency range from about 20 cycles per second to about 20,000 cycles per second. Those skilled in the art will recognize that to get better quality sound, the speakers (transducing devices) are typically constructed to produce sound in different ranges. Thus, transducing speakers can be constructed in a variety of ways to broadcast sound in different ranges which vary based on the transducing speaker, cost, space, audience, and the like. Some transducing speakers are referred to as a mid-range, high frequency (HF), low frequency or bass and the like. The exact frequency range will vary based on a variety of factors. However, low frequency or bass speakers typically produce sound from about 40 to 60 hertz (Hz) to about 450 to 500 Hz; mid-range speakers produce sound from around 70 Hz to 100 Hz to about 3000 Hz, and HF speakers typically produce sound from around 3000 Hz to 3500 Hz to above 20,000 Hz. In other words, while the frequency range for bass, mid-range and HF differ, they may and typically do overlap. 
     High performance automotive speakers are often mounted within plastic speaker enclosures such that sound waves radiating from the front of the speaker diaphragm enter the passenger compartment of the vehicle while sound waves emanating from the back of the speaker diaphragm enter the enclosure. For an automotive speaker to deliver accurate sound reproduction, especially in the low frequency ranges, it is important that the speaker enclosure be rigid enough to resist vibrating in response to the motion of the vehicle and the sound waves generated by the back of the speaker diaphragm. This rigidity requirement represents a significant design challenge in the manufacture of light weight, low cost speaker enclosures. Whereas thin-walled enclosures are desirable from a cost and weight standpoint, care must be taken to ensure that the enclosure walls are adequately reinforced against vibration so that the sound quality of the system is not compromised. 
     Many conventional automotive speaker enclosures are made from injection molded plastic material. The injection molding process allows the thickness of the enclosure walls to be varied such that thicker wall sections may be provided in areas such that thicker wall sections may be provided in areas of the enclosure that would otherwise be susceptible to vibration. 
     Despite the design flexibility offered by injection molding, however, the method has several drawbacks with respect to speaker enclosure manufacture. For example, it is difficult to ensure an airtight seal between the enclosure pieces because of part shrinkage, part twisting, and the irregular complex, 3-D shapes of many speaker enclosure designs. In the absence of an airtight seal between the pieces, the speaker enclosure will not function as intended. 
     U.S. Pat. No. 5,532,437 discloses a speaker assembly for a motor vehicle in which a single speaker is mounted to a blow molded enclosure. 
     Speaker boxes including multiple speakers are commonly mounted to the sports bar of sport utility vehicles to provide music and other audio entertainment for the driver and passengers. Such speaker boxes are typically mounted to extend across the sports bar in a horizontal position. One problem of blow molded speaker boxes is that it is difficult, if not impossible, to manufacture internal features in such enclosures to isolate or acoustically decouple the compartments in which the various speakers are mounted, especially if the speakers are located some distance from each other. 
     The following U.S. patent documents are related to at least one embodiment of the present invention: U.S. Pat. Nos. 5,094,316; 5,532,437; 5,646,381; 5,979,590; 6,076,885; 6,690,802; 7,984,738; 2009/0314770; 2010/0072742; and D469421. 
     Despite the prior art noted above, there is still a need for a speaker system such as a sound bar assembly having improved sound quality, low weight, design flexibility and capable of being mass produced at a relatively low price. 
     SUMMARY OF EXAMPLE EMBODIMENTS 
     An object of at least one embodiment of the present invention is to provide a light weight, thin-walled, compact speaker system such as sound bar assembly having improved sound quality and is capable of being manufactured at high production rates for markets such as the sport utility vehicle market. 
     In carrying out the above object and other objects of at least one embodiment of the present invention, a speaker system having a plurality of speaker units and improved sound quality is provided. The system includes a front panel having inner and outer surfaces and a plurality of mating portions including an outer boundary mating portion formed about the perimeter of the front panel. A first interior mating portion extends between opposite sides of the outer boundary mating portion at a first end of the front panel and a second interior mating portion extending between opposite sides of the outer boundary mating portion at a second end of the front panel. The front panel has a first sound opening at the first end and a second sound opening at the second end. The system also includes a back panel having inner and outer surfaces and a plurality of mating portions that oppose corresponding mating portions of the front panel. The mating portions of the back panel include an outer boundary mating portion formed about the perimeter of the back panel, a first interior mating portion extending between opposite sides of the outer boundary mating portion of the back panel at a first end of the back panel, and a second interior mating portion extending between opposite sides of the outer boundary mating portion of the back panel at a second end of the back panel. Opposing mating portions of the front and back panels are fused or welded together to form outer boundary and interior joints where the front and back panels are joined. The front and back panels are spaced apart at their first and second ends to define first and second speaker compartments, respectively, separated by a central compartment. The system still further includes a first speaker unit positioned in the first speaker compartment and mounted to transmit sound through the first sound opening and a second speaker unit positioned in the second speaker compartment and mounted to transmit sound through the second sound opening. The speaker compartments are acoustically isolated from one another by the interior joints. 
     Each of the compartments may be air or pressure-tight to acoustically isolate the speaker compartments. 
     The front panel may be formed as a unitary molded part from a thermoplastic in an injection molding process. The back panel may be formed as a unitary molded part from a thermoplastic in an injection molding process. The thermoplastic of the front panel may be compatible to be electromagnetically welded with the thermoplastic of the back panel. 
     The mating portions of the panels may be thermoplastic mating portions. The system may further include a weld disposed in spaces between opposing mating portions of the front and back panels and being defined by a thermoplastic electromagnetic material which, when melted and placed under pressure, is caused to conform to the configuration of the spaces to bond to and secure together surfaces layers of the opposing mating portions at the spaces by polymer-to-polymer linkages. 
     The outer surface of the front panel may be a class-A surface and the outer surface of the back panel may be a mounting surface. 
     The system may further include a wiring harness disposed in the central compartment and routed to each of the speaker compartments to couple electrical audio signals to each of the speaker units. 
     The front panel may have first and second depressions at its outer surface at the first and second ends, respectively, of the front panel wherein the system may further include a third speaker unit positioned in the first depression and a fourth speaker unit positioned in the second depression. 
     The first depression may be defined by bottom and side walls which separate the first depression from the first speaker compartment. 
     The second depression may be defined by bottom and side walls which separate the second depression from the second speaker compartment. 
     The system may further include grills for covering the speaker units at the first and second ends of the front panel. 
     The front panel may have a recess at its outer surface between the first and second ends wherein the system may further include a light unit positioned in the recess to emit light. 
     The front panel may have a plurality of depressions. Each of the depressions is at least partially defined by a bottom wall having an opening. The back panel may have a plurality of openings aligned with the openings in the bottom walls when the front and back panels are joined together. The system may further include a plurality of fasteners which extend through the aligned openings to mount the system. 
     The panels may be fused or welded together about the aligned openings. 
     The system may further include a wiring harness disposed in the central compartment and routed to each of the speaker compartments and to each of the depressions to couple electrical audio signals to each of the speaker units. 
     Further in carrying out the above object and other objects of at least one embodiment of the present invention, a speaker system having a plurality of speaker units and improved sound quality for use in a vehicle is provided. The system includes a front panel having inner and outer surfaces and a plurality of mating portions including an outer boundary mating portion formed about the perimeter of the front panel. A first interior mating portion extends between opposite sides of the outer boundary mating portion at a first end of the front panel. The front panel has a first sound opening at the first end and a second sound opening at the second end. The system further includes a back panel having inner and outer surfaces and a plurality of mating portions that oppose corresponding mating portions of the front panel. The mating portions of the back panel include an outer boundary mating portion formed about the perimeter of the back panel, a first interior mating portion extending between opposite sides of the outer boundary mating portion of the back panel at a first end of the back panel, and a second interior mating portion extending between opposite sides of the outer boundary mating portion of the back panel at a second end of the back panel. Opposing mating portions of the front and back panels are fused or welded together to form outer boundary and interior joints where the front and back panels are joined. The front and back panels are spaced apart at their first and second ends to define first and second speaker compartments, respectively, separated by a central compartment. The system still further includes a first speaker unit positioned in the first speaker compartment and mounted to transmit sound through the first sound opening and a second speaker unit positioned in the second speaker compartment and mounted to transmit sound through the second sound opening. The speaker compartments are acoustically isolated from one another by the interior joints. 
     Each of the compartments may be air or pressure-tight to acoustically isolate the speaker compartments. 
     Still further in carrying out the above object and other objects of at least one embodiment of the present invention an overhead sound bar assembly having improved sound quality for use in a sport utility vehicle is provided. The assembly includes a front panel having inner and outer surfaces and a plurality of mating portions including an outer boundary mating portion formed about the perimeter of the front panel. A first interior mating portion extends between opposite sides of the outer boundary mating portion at a first end of the front panel and a second interior mating portion extends between opposite sides of the outer boundary mating portion at a second end of the front panel. The front panel has a first sound opening at the first end and a second sound opening at the second end. The assembly further includes a back panel having inner and outer surfaces and a plurality of mating portions that oppose corresponding mating portions of the front panel. The mating portions of the back panel include an outer boundary mating portion formed about the perimeter of the back panel, a first interior mating portion extending between opposite sides of the outer boundary mating portion of the back panel at a first end of the back panel, and a second interior mating portion extending between opposite sides of the outer boundary mating portion of the back panel at a second end of the back panel. Opposing mating portions of the front and back panels are fused or welded together to form outer boundary and interior joints where the front and back panels are joined. The front and back panels are spaced apart at their first and second ends to define first and second speaker compartments, respectively, separated by a central compartment. The assembly still further includes a first speaker unit positioned in the first speaker compartment and mounted to transmit sound through the first sound opening and a second speaker unit positioned in the second speaker compartment and mounted to transmit sound through the second sound opening. The speaker compartments are acoustically isolated from one another by the interior joints. 
     Each of the compartments may be air or pressure-tight to acoustically isolate the speaker compartments. 
     Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions and claims. Moreover, while specific advantages have been enumerated, various embodiments may include all, some or none of the enumerated advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is an environmental view, partially broken away, of a sport utility vehicle having a speaker system or sound bar assembly constructed in accordance with at least one embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of a speaker system or sound bar assembly constructed in accordance with at least one embodiment of the present invention; 
         FIG. 3  is a top plan view of the speaker system or assembly of  FIG. 2  without speaker or light units; 
         FIG. 4  is a schematic view of a wiring harness including wires, connectors and grommets for use in the system or assembly of  FIGS. 2 and 3 ; 
         FIGS. 5 a  and 5 b    are side schematic views, partially broken away, of tongue and groove mating portions of the front and back panels of the system or assembly prior to and after, respectively, electromagnetic welding; 
         FIGS. 6 a  and 6 b    are side schematic views, partially broken away, of a different type of tongue and groove mating portions of the front and back panels prior to and after, respectively, electromagnetic welding; 
         FIGS. 7 a  and 7 b    are side schematic views, partially broken away, of rib and groove mating portions of the front and back panels prior to and after, respectively, electromagnetic welding; 
         FIG. 8  is a side view, partially broken away and in cross section, of both rib and groove and tongue and groove mating portions of the front and back panels after electromagnetic welding; 
         FIG. 9  is a side view, partially broken away and in cross section, of a rib and groove mating portions of the front and back panels after electromagnetic welding; 
         FIG. 10  is a side schematic view, partially broken away and in cross section, of the bottom panel and illustrating an interior mating portion forward on a rib and extending between opposite sides of an outer boundary mating portion of the panel; and 
         FIGS. 11 a  through 11 c    are schematic views showing an example electromagnetic welding or bonding process before panel or part joining, during part joining and after part joining, respectively. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENT(S) 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     Referring now to  FIG. 1 , a sport utility vehicle generally indicated at  10 , has a sound bar assembly or speaker system, generally indicated at  12 , mounted against the inside surface of the vehicle roof  16  above the passenger compartment. The sound bar assembly  12  extends laterally across substantially the entire width of the vehicle roof  16 . 
     Referring to  FIGS. 2, 3, 5 and 5   b , the system or assembly  12  includes an elongated front panel, generally indicated at  20 , having inner and outer surfaces  22  and  24 , respectively, and a plurality of mating portions including an outer boundary mating portion  26  formed about the perimeter of the front panel  20 , a first interior mating portion  28  ( FIGS. 6 and 6   b ) extending between opposite sides of the outer boundary mating portion  26  at a first end  30  of the front panel  30  and a second interior mating portion  26  extending between opposite sides of the outer boundary mating portion  26  at a second end  32  of the front panel  20 . The front panel  20  has a first sound opening  34  at the first end  30  and a second sound opening  36  at the second end  32 . The first outer surface  24  is typically a class-A surface. 
     Still referring to  FIGS. 2 and 3  and also to  FIG. 10 , the system or assembly  12  also includes an elongated back panel generally included at  40 , having inner and outer surfaces,  42  and  44 , respectively, and a plurality of mating portions that oppose corresponding mating portions of the front panel  20 . The mating portions of the back panel  40  includes an outer boundary mating portion  46  formed about the perimeter of the back panel  40 , a first interior mating portion  48  extending between opposite sides of the outer boundary mating portion  46  of the back panel  40  and a second interior mating portion  48  extending between opposite sides of the outer boundary mating portion  46  at a second end  52  of the back panel  40 . The first and second interior mating portions  48  are formed at the edges  54  of rib plates  56  integrally formed with the rest of the back panel  40 . Opposing mating portions of the front and back panels  20  and  40 , respectively, are fused or welded together to form outer boundary and interior joints, as shown in  FIGS. 5 b , 6 b , 7 b   ,  8 ,  9  and  11   c , where the front and back panels  20  and  40 , respectively, are joined. The front and back panels  20  and  40 , respectively, are spaced apart at their first and second ends  30 ,  32 ,  50  and  52  to define first and second speaker compartments  60  and  62 , respectively, separated by a central compartment  64 . 
     As shown in the exploded perspective view of  FIG. 2 , the system or assembly  12  still further includes a first speaker unit  66  positioned in the first speaker compartment  60  and mounted to transmit sound through the first sound opening  34  and a second speaker unit  68  positioned in the second speaker compartment  62  and mounted to transmit sound through the second sound opening  36 . The speaker compartments  60  and  62  are acoustically isolated from one another by the interior joints provided by the fused or welded interior mating portions  28  and  48 . Each of the compartments  60 ,  62  and  64  is air or pressure-tight to acoustically isolate the speaker compartments  60  and  62 . 
     The front panel  20  is preferably formed as a unitary molded part from a thermoplastic such as a polyolefin with a talc filler in an injection molding process. In like fashion, the back panel  40  is preferably formed as a unitary molded part from a thermoplastic (such as a filled polyolefin) in an injection molding process. The thermoplastic of the front panel  20  is preferably compatible to be electromagnetically welded with the thermoplastic of the back panel  40 . The mating portions of the panels  20  and  40  are thermoplastic mating portions. 
     The system  12  further includes a weld  70  disposed in spaces between opposing mating portions of the front and back panels  20  and  40 , respectively. The weld  70  is defined by a thermoplastic electromagnetic material which, when melted and placed under pressure, is caused to conform to the configuration of the spaces to bond to and secure together surfaces layers of the opposing mating portions at the spaces by polymer-to-polymer linkages, as shown in  FIGS. 5 a    through  9  and  FIGS. 11 a -11 c   . As shown in  FIG. 11 a   , before joining, the weld material  70  such as strips of thermoplastic electromagnetic material are deposited in the joints. The mating portions or parts are brought together and placed within a fixture containing a work coil  72 . During joining, the coil  72  is activated to heat the weld material  70 , causing the adjoining surfaces of the mating parts or portions to melt as shown in  FIG. 11 b   . After joining and as shown in  FIG. 11 c   , the weld material  70  has filled the joint. The process has fused the mating parts (i.e. the front and back panels,  20  and  40 , respectively), resulting in polymer-to-polymer linkages therebetween at the mating portions. 
     Referring again to  FIGS. 2 and 3 , the front panel  20  has first and second depressions  82  and  84 , respectively, at its outer surface  24  at the first and second ends  30  and  32 , respectively, of the front panel  20 . The system  10  further comprises a third speaker unit  86  positioned in the first depression  82  and a fourth speaker unit  88  positioned in the second depression  84 . The first and second speaker units  66  and  68  may be bass/midrange speaker units and the third and fourth speaker units  86  and  88 , respectively, may be higher frequency speaker units or tweeters. The first depression  82  is defined by bottom and side walls which separate the first depression  82  from the first speaker compartment  60 . The second depression  84  is defined by bottom and side walls which separate the second depression  84  from the second speaker compartment  62 . 
     The system  12  further includes grills  90  and  92  for covering the speaker units  86 ,  66 ,  68  and  88  at the first and second ends  30  and  32  of the front panel  20 . 
     The front panel  20  has a recess  94  at its outer surface  24  between the first and second ends  30  and  32 . The system  10  further includes a light unit  96  positioned in the recess  94  to emit light. 
     As shown in  FIGS. 2 and 4 , the system or assembly  12  further includes a wiring harness generally included at  80 , routed to each of the speaker compartments  60  and  62  to couple electrical audio signals to each of the speaker units  66  and  68 . The wiring harness  80  is routed to each of the compartments  60 ,  62  and  64 , to each of the depressions  82  and  84  and to the recess  94  (through holes formed in the bottom walls of the depressions  82  and  84  and the recess  94 ) to couple electrical audio signals to each of the speaker units  86  and  88  and electrical power to the light unit  96 . The wiring harness  80  includes a plurality of wires  81  and a plurality of interconnecting molded-in grommets  83  which seal the wiring harness  80  within holes in the walls  82  and  84  and the ribs  56 . The wiring harness  80  also includes a multi-pin, main connector  85  adapted to be connected to a connector (not shown) coupled to the electrical system of the vehicle  10 . The wiring harness  80  further includes a plurality of connectors  87  for connection to each of the speaker units  66 ,  68 ,  86  and  88  and the light unit  96 . 
     The front panel  20  also preferably includes apertures  110  which are aligned with apertures  112  formed in the back panel  40 . The aligned apertures  110  and  112  provide attachment locations for cups (not shown) which are secured to the front panel  20  and the roof  16  by bolts (not shown) which extend through the cups. Preferably, the panels  20  and  40  are fused or welded together about the aligned apertures  110  and  112  by the previously described weld material using the previously described electromagnetic weld process. 
     Preferably, the weld material  70  includes strips of thermoplastic electromagnetic weld material, such as EMAWELD® material, positioned in channels or grooves formed in the mating portions of the bottom panel  40  as shown in  FIG. 11   a.    
     As shown in  FIG. 11 b   , an electromagnetic field is then established about the EMAWELD® material positioned in the channels or grooves and in the space between the mating portions of the front and back panels  20  and  40 , respectively, for a time sufficient to melt the material. The molten material, in turn, melts surface layers of the melting portions of the front and back panels  20  and  40  which contact the molten material. This step can be accomplished by controllably energizing the electromagnetic transmission coils (use of which is shown in  FIGS. 11 a -11 c    at  72 ) coupled to an induction generator (not shown), such as an induction generator generally available from Emabond® systems, a division of Ashland Chemical Company, of Norwood, N.J. 
     The adjacent surfaces of the mating portions are forced together as indicated by arrows  74  in  FIG. 11 b    to cause the molten material to flow within the channels and the space between the mating portions of the front and back panels  20  and  40 , respectively, to further cause surface layers of the mating portions to melt. 
     The molten material and the molten surface layers are allowed to cool and solidify as shown in  FIG. 11 c   . In this way, the material fuses with the mating portions causing polymer-to-polymer linkages. This provides extremely strong bonds considering the relatively small surface area by which the front panel  20  is secured to the back panel  40 . 
     In this way, the welds formed by the thermoplastic electromagnetic material provide very strong yet narrow bonds between the front and back panels  20  and  40 , respectively. These welds can be located very close to the wiring harness  80  without damaging the wiring harness  80  during manufacturing. The bonds between the front and back panels  20  and  40 , respectively, even though occupying a relatively small amount of surface area, are strong enough to maintain the acoustical isolation between the speaker compartments  60  and  62  despite vibration and extreme weather conditions within the passenger compartment of the vehicle  10 . 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.