Abstract:
An interchangeable cover is secured between a lower base and an upper cover retention body over an inflatable dome. The entire assembly is placed on a chair for an individual to sit on for stability core training. The upper cover retention body and lower base detach from compressive engagement of the interchangeable cover to replace the cover as desired by the individual.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to exercise equipment. More specifically, it relates to an apparatus to interchange aesthetically-pleasing covers over balance domes used for core training. 
     2. Brief Description of the Related Art 
     Balance domes are inflatable, stationary exercise devices. They are inflated to a pressure whereby sitting, standing, kneeling, pushing or otherwise engaging the dome compresses the inner plenum and deforms the dome&#39;s shape. As the dome deforms, the person engaging the dome must shift his or her center of balance in response. 
     A primary benefit of exercising with a stability dome as opposed to exercising directly on a hard flat surface is that the body responds to the instability of the dome to remain balanced, engaging many more muscles. Those muscles become stronger over time to keep balance. Most frequently, the core body muscles, the abdominal muscles and back muscles, are the focus of balance dome exercising. 
     Balance domes have found their way into the workplace with individuals sometimes sitting on spherical stability balls instead of regular chairs. However, for a variety of reasons, both practical and aesthetic, many individuals forgo the use of stability balls. 
     Another option for individuals is to use a balance dome placed upon a chair. While the movement is more confined than that of a stability ball there is still more development of core muscles than in sitting in a chair without the dome. However, one drawback to this option is the aesthetics of the dome itself. Most domes are manufactured with the anticipation they will be used in a gym environment. Therefore, the colors are typically bright pastels which are not suitable or pleasing in a work or home environment. 
     One possible option is to provide covers for the otherwise unattractive appearance of the balance dome. It is known in the art to manufacture zip-on covers for spherical, stability balls. However, sewing a cover for a ball (or a dome for that matter) is generally a complicated process involving fabrication of darts, pleats or gores to shape the sphere or half-sphere. For individuals that want to tailor the aesthetic appearance of their balance dome to the surrounding décor, the work involved is substantial. 
     What is needed in the art is an apparatus to easily interchange covers over a balance dome without requiring sophisticated sewing and patterning. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome. 
     BRIEF SUMMARY OF THE INVENTION 
     The novel structure for interchanging balance dome covers includes a substantially rigid base for supporting the lower, planer surface of an inflatable balance dome. The base may be constructed of wood, metal, hard plastic or the like. For balance domes intended to be placed on chairs, it is preferred that the rigid base be substantially rectangular in shape having length/width dimensions between 12 and 24 inches. A rectangular base helps secure the dome on the chair seat so that the instability of the apparatus is limited to the deformity resulting from sitting on the dome by the user. 
     The dome&#39;s base lays on top of the rigid base. The dome&#39;s base is a lower, planer surface having a first diameter (the largest diameter of the dome). The interior of the inflatable dome is defined by interstitial space forming a plenum of sufficient pressure to bear the weight of a human sitting on it with some deformity occurring in the inflatable balance dome due to compression of the plenum. Across a population of humans there is a substantial variability of weight. Therefore, the pressure (plenum) inside the dome may be adjusted to accommodate heavier and lighter individuals. 
     Over the inflatable dome is placed a dome cover intended to be primarily aesthetic. However, the present invention anticipates that dome covers may be constructed with tactical surface features having therapeutic and/or physiologic use. The dome cover has an annular, lower flange about its circumference of a second diameter, the second diameter greater than the first diameter of the base of the inflatable dome. This flange provides a surface in which to “lock” the cover in place over the dome. 
     A cover retention body mates with the rigid base sandwiching the lower flange of the dome cover in between. The retention body has an outer perimeter substantially the same as the rigid base. The cover retention body has an annular opening of approximately the first diameter though which the inflatable dome and cover project. 
     A retention mechanism secures the cover retention body, dome cover and inflatable balance dome to the rigid base whereby the annular, lower flange of the dome cover is compressively sandwiched between the retention body and the rigid base. At least one hinge pivotably couples the cover retention body to the rigid base on a first end of the base wherein a locking mechanism is positioned at a second end of the apparatus distal to the first end. Upon disengagement of the locking mechanism the rigid base-cover retention body assembly pivots open about the axis of the hinge to release the dome cover lower flange from compressive engagement. 
     In an alternative embodiment of the invention, at least two screw interfaces but preferably four equidistantly spaced proximate to each corner of the rectangular base threadably receive screws which compressively sandwich the dome cover lower flange between the cover retention body and the rigid base. 
     In yet another alternative embodiment of the invention, at least two openings in the upper surface of the rigid base are provided. Each opening has a first aperture and a second smaller aperture in open communication with the first aperture. An interstitial space underneath the second smaller aperture is of greater or equal width of the first aperture. Each opening receives a downwardly projecting pin affixed to the lower surface of the retention body, each pin having an annular head with a diameter less than the first aperture of the correspondingly aligned opening in the upper surface of the rigid base but greater than the second smaller aperture. Each projecting pin head on the lower surface of the retention body is aligned to be received initially by a first aperture and then slideably received by the interstitial space underneath the second smaller aperture. The diameter of the pin between the pin head and the lower surface of the retention body is less than or equal to the second smaller diameter aperture. In an embodiment of the invention, the pin and smaller diameter aperture form an interference fit. 
     In yet another alternative embodiment of the invention, the at least two openings may be formed in the lower surface of the invention body and the pins project upward from the upper surface of the rigid base. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
         FIG. 1  is a partially sectional, side elevation view of an embodiment of the invention. 
         FIG. 2  is an exploded, side elevation view of an embodiment of the invention. 
         FIG. 3  is a partially sectional, top down view of an embodiment of the invention. 
         FIG. 4  is a top down view of an embodiment of the invention. 
         FIG. 5  is a side elevation view of an embodiment of the invention on a chair seat. 
         FIG. 6  is a top down view of an embodiment of the invention. 
         FIG. 7  is a partially sectional, exploded side elevation view of an embodiment of the invention. 
         FIG. 8  is a top down view of an embodiment of the invention. 
         FIG. 9  is a close-up view of an opening used in  FIG. 8 . 
         FIG. 10  is a top down view of an embodiment of the invention. 
         FIG. 11  is a top down view of an embodiment of the invention. 
         FIG. 12  is a partially sectional, exploded side elevation view of an embodiment of the invention. 
         FIG. 13  shows side elevation views of a plurality of dome covers according to the invention. 
         FIG. 14  is a bottom-up view of rigid base according to an embodiment of the invention. 
         FIG. 15  is a bottom-up view of rigid base according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The novel structure is denoted as a whole in  FIG. 1  by the reference numeral  10 . Inflatable balance (or stability) dome  20  is pressurized with air. Dome cover is received over balance dome  20  and is secured by substantially rigid base  40  and cover retention body  50 . In  FIG. 2 , an exploded view of the assembly is shown. Cover  30  has an annular, lower flange  35  which provides a surface area upon which cover retention body  50  and rigid base  40  sandwich with compressive force and secured by upper and lower locks  60  and  70  respectively. 
     In an embodiment of the invention, cover retention body  50  and rigid base  40  pivot about an axis defined by hinge  80 .  FIG. 3  shows a top down view of an embodiment of the invention having hinges  80   a - b . Cover retention body  50  has a large circular opening  55  in which balance dome  20  and cover  30  project.  FIG. 4  shows the same embodiment wherein upper lock  60  and lower lock  70  are disengaged and cover retention body  50  is pivoted to an open state with cover  30  removed. 
       FIG. 5  shows the embodiment in one intended use on the seat of chair  90 . As an individual sits on the apparatus, the dome compresses and deforms causing the individual to frequently shift his or her weight. This shifting of weight exercises the muscles of the abdomen and back. 
       FIGS. 6-7  show an alternative embodiment of the invention. Instead of using hinge  80 , four screw engagements  100   a - d  lock down cover retention body  50  to rigid base  40 . Threaded apertures  110   a - b  in retention body  50  align with corresponding threaded apertures  120   a - b  in rigid base. 
       FIGS. 8-12  show an alternative embodiment of the invention wherein the retention body  50  and rigid base  40  twist upon a center axis to engage and disengage the cover.  FIG. 8  shows the rigid base  40  having openings  130   a - d  in its upper surface. Each opening  130  has a first aperture of diameter d 1  and a second aperture of diameter d 2  wherein d 2  is less than d 1  as shown in  FIG. 9 . Pins  140   a - b  ( FIG. 12 ) project downwardly from retention body  50 . Each pin  140  has an annular head with a diameter less than that of the first aperture in opening  130 . Under second aperture in opening  130  is an interstitial space of greater or equal width of the first aperture and design to laterally receive annular head of pin  140 . 
     As shown in  FIG. 10 , pins  140   a - d  align with first aperture of openings  130   a - d . The annular head of each pin is small enough to be received with first aperture but not by second aperture. Once pins  140   a - d  are inserted, retention body  50  is rotated clockwise with respect to rigid base  40  which causes pins  140   a - d  to slide into second aperture of opening  130 . Annular head of each pin locks into the interstitial space underneath second aperture. As annular head&#39;s diameter is larger than that of second aperture, rigid base  40  and retention body  50  are locked in place thereby securing cover  30  over dome  20 . 
       FIG. 13  is an illustrative side elevation view of variations to cover  30   a - f  which are easily interchanged over dome according to the invention. 
       FIG. 14  is an alternative embodiment of the invention that provides carrying handle  150  affixed to rigid base  40 . In addition, inflatable dome  20  has inflation valve  170  located in the center axis of the dome shape at the bottom portion of the inflatable dome  20 . To provide access to the inflation valve  170  while the retention body  50  and rigid base  40  are locked together an access opening  160  is provided in rigid base  40 . 
     In yet another alternative embodiment of the invention, air pump  180  is integral to rigid base  40  and in fluid communication with inflation valve  170 . This way an individual may adjust the pressure of the inflatable dome  20  to provide the desired level of stability (or instability) based on the plenum pressure within inflatable dome  20 . 
     GLOSSARY OF CLAIM TERMS 
     Rigid Base: means a substantially planer surface upon which the inflatable dome rests. The base may be of any predetermined geometric configuration but has a perimeter substantially the same as cover retention body. 
     Cover Retention Body: means a substantially planer surface having a circular opening through which the inflatable dome and cover assembly are received. The cover retention body compresses an outer flange of material of the cover against the rigid base to hold the cover in place. 
     Retention Mechanism: means a latch, screw, lock or other mechanical means to hold to the rigid base against the cover retention body thereby locking the cover between them. 
     The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.