Abstract:
A portable spa including an audio system designed to use the spa shell as the sound generating device. Transducer devices are bonded to the spa shell so as to couple the sound vibration energy to the shell.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of an application for Spa Audio System, U.S. Ser. No. 10/364,080, filed Feb. 11, 2003, which is a continuation of an application for Spa Audio System, Ser. No. 09/516,132, filed Mar. 1, 2000, now U.S. Pat. No. 6,556,684. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The subject invention relates generally to spas and more particularly to an audio system utilizing a spa shell as the sound-generating device.  
         [0004]     2. Description of Related Art  
         [0005]     Existing spa audio systems use traditional speakers wherein the audio drivers are exposed to the harsh spa environment and/or require protection or the use of esoteric materials to prevent premature failure. Existing spa audio systems also suffer from the limited space available to mount speakers. The resultant smaller speakers are incapable of producing full range audio (50 Hz-17 kHz).  
       SUMMARY OF THE INVENTION  
       [0006]     According to the invention, a spa shell is employed as an audio driver with audio transducers mounted inside the skirt of the spa directed to the underside of the spa shell. The inventor has found that the spa shell provides both sufficient rigidity for high frequency reproduction and a sufficiently large surface area to achieve low frequency reproduction. A transducer mounting block is attached to the underside of spa shell by an adhesive or other suitable means. A preferred attachment mechanism is a pre-formed metal mounting plate embedded in the plastic underside layer of the spa shell to which an audio transducer is fastened. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The exact nature of this invention as well as the objects and advantages will be readily apparent upon consideration of the following specification describing the preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein:  
         [0008]      FIG. 1  is a schematic cross-sectional diagram illustrating a spa audio system according to a preferred embodiment;  
         [0009]      FIG. 2  illustrates an enclosure apparatus for attaching transducers to the spa shell;  
         [0010]      FIG. 3  is a schematic diagram of an alternate embodiment employing an RF transmitting device.  
         [0011]      FIG. 4  is a top elevation of a transducer mounting plate;  
         [0012]      FIG. 5  is a cross-section of the mounting plate of  FIG. 4  along line  5 - 5 .  
         [0013]      FIG. 6  is a top elevation of an alternate transducer mounting plate;  
         [0014]      FIG. 7  is a cross-section of the mounting plate of  FIG. 6 , along line  7 - 7 ;  
         [0015]      FIG. 8  is a perspective of transducer mounting plate attached to the underside of a spa shell; and  
         [0016]      FIG. 9  is a cross-section of a portion of a spa sheet showing a transducer mounting plate embedded in the underside of a spa shell. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]      FIG. 1  illustrates a spa audio system according to a preferred embodiment. According to this embodiment, audio transducer devices  11  are bonded to a spa shell  13 . The transducer devices  11  couple the sound vibration energy so that sound can be heard when using the spa. Two transducer devices  11  are preferably provided for stereo effect but one device, or more than two devices, may also be used. The transducer devices  11  may be driven by a conventional integrated audio amplifier  15 , providing, e.g., 100-300 watts per channel.  
         [0018]     The spa shell  13  is rigid enough to support the weight of water and bathers but is sufficiently compliant to reproduce full range audio. A typical spa shell  13  is formed of a thermoset plastic, thermoplastic or acrylic top sheet having a thickness of 0.100-0.300 inches. As is well known in the spa industry, additional layers of material (not shown) are provided to the underside of the shell  13  to provide structural support. Of course, other materials and dimensions providing the functional prerequisites for water/bather support and audio transmission may be employed.  
         [0019]     Rigid engagement of each transducer device  11  to the spa shell  13  is required. One installation method preferably prevents spa insulation material such as structural foam applied to the underside of sheet  13  from contaminating the transducer/shell coupling. This is achieved by constructing the transducer device  11  as a formed enclosure that surrounds a transducer element and installing it to the spa shell  13  before the insulation material is applied to the underside of the shell  13 . A suitable audio transducer element is Model TST 329 as available from Clark Synthesis, Inc., 8122 S. Park Lane, Littleton, Colo. 80120.  
         [0020]     An illustrative formed enclosure  111  is shown in  FIG. 2 . This enclosure  111  includes a thermoformed molded plastic housing  113 , which may be fabricated, for example, from ⅛″ ABS plastic. The housing  113  includes an outer cylindrical shell portion  115 , which provides a circular rim or edge  117 , which is open.  
         [0021]     Adjacent the open rim  117  of the enclosure  111 , a somewhat smaller concentric cylindrical portion  119  is provided, which is of a diameter selected to support the outer rim  118  of the transducer element  121 . A nut  123  is threaded onto a threaded projection of the transducer  121  and receives a threaded end of a stud  125 . The stud  125  threads into a cylindrical block, plug or puck  127  formed of plastic or metal at a closed end  129  of the housing  113 , thereby attaching and further supporting the transducer  121  within the housing  113 .  
         [0022]     Attachment of the housing  113  and the cylindrical block  127  to the spa shell  13  is preferably provided by using a thermoplastic adhesive for gluing the end  129  of the housing  113  to the shell  13  ( FIG. 1 ). Or, or structural foam could also be used to attach the housing to the shell  13 . The puck  127  is then glued to the inside of the housing  113  at the closed end  129  with any suitable adhesive. The block  127  and the housing  113  are embedded in the structural foam underside of the shell  13  and are held fast to the shell  13  by the structural foam and the adhesive.  
         [0023]     Additionally, support to the lower end  131  of the housing  113  may be provided, for example, via a brace attached to the spa frame structure at the lower end  131  of the housing in order to relieve any shear stress created by hanging the housing/transducer assembly off the side of the spa shell  13 . A hatch or door in the spa skirt  21  ( FIG. 1 ) may also be provided to access the speaker enclosures  111  through the open ended rim  117  of housing  113 .  
         [0024]     The output signal of the amplifier  15  may be coupled to the transducers via conventional speaker wire  17 . In such case, the amplifier  15  and audio components  19  supplying it, such as preamplifiers and/or CD players, may be located in a compartment within the spa skirt  21  or at a remote site. Alternatively, as shown in  FIG. 3 , a remote transmitting device  23  (e.g., RF) may be used to enable use of a homeowner&#39;s home audio system  25  as the music signal source. Such remote transmitting devices are commercially available. For example, the 900 MHz or 2.4 GHz wireless receiver/transmitters provided by X-10 USA, Closter, N.J. 07624, may be used. In such case, a receiver  27  located at the spa provides the home audio signal to the amplifier  15 , which then drives the transducers  11 .  
         [0025]     In operation, the audio can be heard under water  29  as well as above the water  29 . Listeners outside the spa can also hear the audio signal, but the experience is muted compared to that of the tub occupant.  
         [0026]     The means of attaching an acoustic driver to the spa shell is important, in order to cause the spa shell to function as a speaker cone driven by the audio transducer attached to it, with a frequency range comparable to an average speaker system. The attachment means is important also to the extent that it must perform in a harsh outside, and perhaps wet, environment, without breaking down. If the interface connection between the spa shell and the audio transducer breaks down, by coming loose, for example, the function of the entire system fails.  
         [0027]     Besides using appropriate compatible adhesives to attach mounting blocks to the underside of the spa shell, for mounting audio transducers, it has been found that the use of mounting plates bonded to the underside of a spa shell is also very effective to couple the audio transducer to the spa shell itself.  
         [0028]     A mounting plate  33 , according to the present invention, is shown in  FIGS. 4 through 7 . The mounted plate  33  may be made of plastic metal, and is preferably made out of a material of sufficient strength to withstand considerable flexure forces over a long period of time without fatigue. The mounting plate, when made of metal, is preferably about 4 inches in length and 4 inches in width and about 0.13 inches thick. The mounting plate  33  has a plurality of holes  35  scattered throughout the plate in a random pattern, each hole being about 0.83 inches in diameter.  
         [0029]     The mounting plate  33  carries a plurality of mounting studs  37 / 41  which are either externally or internally threaded. Mounting studs  37  are externally threaded. Mounting studs  41  are internally threaded. The studs  37 / 41  are attached to the mounting plate  33  by threading into mounting plate  33  or by some other convenient fixing means, such as welding, or by nuts (not shown).  
         [0030]     Referring now to  FIG. 8 , mounting plate  33  with its audio transducer mounting studs  37 / 41  is shown attached to the underside of the spa shell  13 . Spa shell  13  has a top side  13 A formed of an acrylic plastic, for example, and a bottom side  45  having one or more layers of fiberglass. The audio transducer mounting plate  33  is held fast to the underside  45  of spa shell  13  by being embedded in the fiberglass underside  45  in a manner more specifically shown in  FIG. 9 .  
         [0031]      FIG. 9  is a cross-sectional illustration of a portion of the spa shell invention showing how the audio transducer mounting plate  33  is embedded in the underside layers  45 A and  45 B of the spa shell  13 . The top side of spa shell  13  may be an acrylic synthetic material or similar plastic, as mentioned earlier, which is supported on its underside by one or more layers of fiberglass or other similar material for providing support and strength to the spa shell  13 . Besides fiberglass, the underside layers  45 A and  45 B may also be any suitable thermoplastic material.  
         [0032]     The audio transducer mounting plate  33  with its transducer mounting studs  37 / 41  thereon is embedded in the fiberglass layer  45 A while it is still soft so that the fiberglass material of layer  45 A holds the mounting plate  33  in place, while a second subsequent layer  45 B of fiberglass material is laid over the first layer  45 A and mounting plate  33 . During this layering process, the holes  35  in mounting plate  33  are filled by the fiberglass material, effectively forming bonding plugs through each one of the holes  35  in the mounting plate, causing the plate  33  to be held at each one of the different locations along its surface. Each one of these bonding plugs acts as rivets, holding the plate at a separate location on its surface. This redundancy of fastening a plate to the underside of spa shell  13  insures longevity for the attachment and the necessary rigidity required to transfer vibration energy from the audio transducer to the shell itself.  
         [0033]     As may be appreciated, the preferred embodiments permit the audio transducer devices to be enclosed within the spa, providing improved aesthetics by eliminating exposed speaker locations. Enclosing the transducer devices within the spa also protects them from water and reduces the risk of water exposure to electrical signals. Moreover, the bonding of the audio transducer to the spa shelf according to the present invention turns the spa shell into a speaker with a surprising frequency range.  
         [0034]     From the above description, those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described herein.