Abstract:
A drum hoop having an asymmetrical cross section for use in combination with hand drums. The drum hoop upper inner edge is connected to a lower inner edge having a larger diameter producing a drum hoop inner surface having an angular orientation to the central axis of the drum. The angular orientation of the inner surface maximizes clearance between the drum hoop and the variable diameter exterior surface of the drum shell. Added clearance allows a drum hoop constructed according to the invention to accommodate variations in exterior surface diameter often encountered in hand made drum shells common in the art.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of musical drums and is more particularly directed to a drumhead and associated drum hoop. The drum hoop is specifically adapted to be used in conjunction with hand drums. 
     Hand drums refer to musical drums that are usually played with the hand instead of with sticks, e.g., conga, bongo, djembe and bata drums. Hand drums have a generally cylindrical drum shell, typically constructed of wood, which has an open top and bottom. Shells for hand drums, such as conga drums, frequently have a shape which is larger around the middle and tapered toward the top and bottom openings. The top opening is usually covered with an animal skin drumhead tightened and tuned to a desired musical tone. Traditionally, such animal skins were tightened over the top of the wooden drum shell by the use of rawhide binding strips, twine or rope, producing a drum and head assembly not easily tuned or modified. While natural skin drumheads produce beautiful musical tones, they are also very sensitive to atmospheric changes such as heat and humidity. Large changes in temperature or humidity can dramatically change the musical tone of a natural skin drum head and render drums so equipped unplayable. 
     To address these disadvantages, musical instrument makers have developed synthetic drumheads closely approximating the musical characteristics of traditional skin drumheads. Synthetic drumheads are constructed from sheets of synthetic material joined to a drum hoop and formed to fit over the open top of a drum shell. The drum hoop is sized to pass over the open top end of a drum shell and be drawn toward the bottom of the drum shell by a counterhoop and tensioning mechanisms. Using such an arrangement makes changing drumheads and tuning of hand drums relatively quick and easy. 
     Being a traditional instrument in many cultures, hand drums are often constructed by hand, resulting in significant variations in the size of the outside diameter of the drum shell and the slope of the taper of the drum shell. As a drum hoop is drawn over the top of a drum shell toward the bottom of the drum shell for tuning purposes, clearance must be maintained between the exterior surface of the drum shell and the inner surface of the drum hoop. Contact between the hoop lower inner edge and the exterior surface of the drum shell will interfere with hoop movement, making tuning the drum impossible. 
     Conventional manufactured drum hoops for hand drums are constructed from a symmetrical U-shaped metal channel into which the peripheral edge of a synthetic drumhead is secured by use of a glue or resin. Uniformly sized, symmetrically shaped manufactured drum hoops often fail to provide sufficient clearance to accommodate the size and taper variations found in hand made hand drum shells and therefore cannot be used. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a uniquely configured drum hoop which has an asymmetrical cross section and an angled lower inner surface to maximize the available clearance between the lower inner surface of the drum hoop and the exterior surface of a hand drum shell. 
     According to a general aspect of the present invention, a hand drum hoop has an angled inner surface connecting an upper inner edge with a lower inner edge having a larger diameter so that the inner surface angles away from the exterior surface of the hand drum shell. Such a construction maximizes available clearance between the drum hoop and the hand drum shell, especially in synthetic drumhead/manufactured drum hoop combinations on hand drums which vary in size and configuration. 
     The drum hoop is preferably constructed from extruded material formed into an annular channel having a diameter sized for a particular type of drum. The annular space enclosed by the channel of the drum hoop will accommodate insertion of the peripheral edge of the drumhead sheet and resin to secure the drumhead sheet to the drum hoop. 
     An object of the present invention is to provide an new and improved hand drum hoop which will accommodate variations in size of the hand drum shell. 
     Another object of the present invention is to provide a new and improved hand drum hoop which will allow the use of synthetic drum heads on a wide variety of handmade hand drums. 
     A further object of the invention is to provide a new and improved hand drum hoop utilizing modern manufacturing methods which is compatible with handmade hand drum shells. 
     These and other objects, features and advantages of the invention will become readily apparent to those skilled in the art upon reading the description of the preferred embodiments in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic cross-sectional view of a drum hoop constructed according to the present invention; 
     FIG. 2 is a schematic cross-sectional view of a prior art drum hoop; 
     FIG. 3 is a cross-sectional view, partly in phantom, of a drum shell (partially illustrated), a drumhead consisting of a drumhead sheet and drum hoop constructed according to the present invention and a counter-hoop in an installed configuration; 
     FIG. 4 is a schematic top view of the drum hoop of FIG. 1; and 
     FIG. 5 is a schematic bottom view of the drum hoop of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in more detail and initially to FIG. 1, a drum hoop  10  constructed according to the present invention is shown in cross section. The drum hoop  10  may be constructed of extruded material and has an asymmetrically U-shaped cross section. Aluminum is a preferred material due to its rigidity, appearance and other properties. The cross section of FIG. 1 can be contrasted with the prior art drum hoop cross section illustrated in FIG.  2 . The drum hoop  10  of FIG. 1 has an upper inner edge  14 , an upper outer edge  18 , and a lower inner edge  26 . An interior surface  16  connects the upper inner and upper outer edges and defines an interior space  20 . Upper inner  14  and lower inner  26  edges are connected by inner surface  12 . (As used in this application, “inner surface” means the surface of a drum hoop which is adjacent the exterior surface of a drum shell when the hoop is installed over a drum shell.) Upper inner edge  14  has a first diameter and lower inner edge  26  has a greater second diameter. In a preferred embodiment, inner surface  12  takes the form of a substantially conical annular surface having an angular orientation g to a central axis. 
     The cross section of drum hoop  10  illustrated in FIG. 1 can alternatively be described in terms of an inner leg  64 , an outer leg  66  and a connecting portion  68  joining the inner and outer legs in a radially spaced relationship. The inner leg  64  begins at the upper inner edge  14 , has a vertical portion  70  parallel to the central axis A and an angled portion  72  including an annular barb  22  and ends at the lower inner edge  26 . The connecting portion  68  joins the lower inner edge of the inner leg  64  to the outer leg  66 . The outer leg  66  begins at the upper outer edge  18  which forms a lip projecting toward the upper inner edge  14  and extends to the juncture with the connecting portion  68 . The outer leg  66  is substantially parallel to the central axis A and has annular barbs  24  projecting into the annular interior space  20  defined by the drumhead hoop  10 . 
     Referring now to FIG. 3, which illustrates a cross sectional view of a hand drum utilizing a drum hoop  10  constructed according to the present invention, the peripheral edge  58  of a drumhead sheet  32  is affixed within the annular interior space  20  of a drum hoop  10  forming a drumhead. The assembled drumhead sheet  32  and drum hoop  10  are placed over a first end  52  of a drum shell  34 . A counter hoop  30  is placed over the first end  52  of the drum shell  34  and engages the drum hoop  10 . Tensioning means  60  engage counter hoop  30  and draw the counter hoop  30  and drum hoop  10  toward the second end  62  of the drum shell  34  creating tension in the drumhead sheet  32  between the bearing areas  36  of the drum shell  34 . 
     FIG. 3 illustrates the physical relationships between the interior surface  12  of the drum hoop  10  and the tapered exterior surface  38  of the drum shell  34 . The exterior surface  38  of the drum shell  34  is of variable diameter. Many hand drum shells are produced by hand and have exterior surfaces  38  which vary in their diameter and in their angular orientation to the drum central axis A. 
     Frequently, a prior art drum hoop  40  (illustrated in FIG. 2) would fail to provide sufficient clearance between that hoop&#39;s inner surface  42  and the exterior surface  38  of the drum shell  34  causing physical contact which interferes with tuning and use of the drum. The present invention provides much needed additional clearance between the interior surface  12  of the drum hoop  10  and the exterior surface  38  of the drum shell  34  by providing a lower inner edge  26  of the drum hoop  10  having a greater diameter than the upper inner edge  14  of the drum hoop  10 . 
     In the preferred embodiment illustrated in FIGS. 4 and 5, the larger diameter D 2  of the lower inner edge  26  induces an angular orientation to the inner surface  12  connecting the upper inner  14  and lower inner  26  edges. According to a preferred embodiment illustrated in these figures, the angular orientation of the inner surface  12  to the central axis A which is represented by the symbol β in FIGS. 1 and 3. β for the illustrated preferred embodiment is approximately 35 degrees. However, an acceptable range for β is between 20 and 60 degrees. 
     When installed adjacent to the exterior surface  38  of a drum shell  34  the angled orientation of the inner surface  12  of a drum hoop  10  can be seen in FIG. 3 to produce additional clearance between the drum hoop  10  and the outer surface  38  of the drum shell  34 . This additional clearance is represented by radii R 1  between central axis A and upper inner edge  14  and R 2  between central axis A and lower inner edge  26 , R 2  being greater than R 1 . 
     Referring now to FIG. 2, it can be seen that the symmetrical configuration of the prior art drum hoop  40  as illustrated produces an inner surface  42  parallel to central axis A and would provide no extra clearance between the prior art drum hoop  40  and the exterior surface of a drum shell. 
     Referring now to FIGS. 4 and 5 which are schematic top and bottom views, respectively, of a drum hoop  10  constructed according to the present invention. (It should be noted that these figures are not drawn to scale. The dimensions of the drum hoop  10  are exaggerated with respect to the hoop diameter for clarity.) FIG. 4 is a schematic top view of a preferred embodiment of a drum hoop  10  constructed according to the present invention. The drum hoop  10  has an upper inner edge  14  having a first diameter D 1  and an upper outer edge  18 . The inner surface  12  connects to the outer surface  28  at the lower inner edge  26 . (This junction is illustrated in FIG. 5.) Looking into the annular interior space  20  from above, an annular barb  22  can be seen. As also illustrated in FIG. 1, the annular barb  22  is located on the interior surface of the angled portion of the drum hoop and so is shown in it&#39;s axially outwardly displaced position. 
     FIG. 5 is a bottom schematic view of a preferred embodiment of a drum hoop  10  constructed according to the present invention. Inner surface  12  and outer surface  28  are shown meeting at lower inner edge  26 . FIG. 5 also illustrates diameter D 1  of the upper inner edge in contrast to greater diameter D 2  of the lower inner edge  26 . In the preferred embodiment illustrated in FIGS.  1  and  3 - 5 , inner surface  12  forms a substantially conical surface having an angular orientation β to the central axis A. 
     A preferred embodiment illustrated in FIG. 1 also contains annular barbs  24  and an overhanging upper inner edge  18  which work in conjunction with annular barb  22  to engage and retain the resin (not illustrated) used to secure the peripheral edge  58  of drum head sheet  32  in the annular interior space  20  of the drumhead hoop  10 . 
     A drum hoops constructed according to the present invention will be substantially rigid and have diameters ranging from 6 inches to 2 feet depending on the size of the drum shell. The span of the annular channel defined by the upper inner and upper outer edges of drum hoops constructed according to the present invention will be in the range of ¼ to 1 inch, depending on the size of the drum shell and the material used for the drum hoop and the drumhead sheet. The angular orientation of the inner surface to a central axis may be in the range of 20 to 60 degrees but is preferably closer to 35 degrees. 
     Other modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. This description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and method may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved.