Abstract:
A toy top includes a body portion including a circumferential slot thereabout adapted to receive wound therein a portion of a cord used to launch the top. The top spins about a spin axis and is configured so that the slot is at or adjacent the center of gravity of the top. The body portion includes an interior shaft portion extending within the body portion, and an exterior shaft portion extending from the body portion. The cord is attached to a collar attached to the top of the external shaft portion. The cord is rotatably attached relative to the body portion. A weapon may be attached to the body portion, and players may battle their tops using respective weapons.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a toy spinning top. 
       SUMMARY OF THE INVENTION 
       [0002]    Performance of a toy spinning top launched by a cord wound about the top can be improved based on, among other things, the locations of the center of gravity (cg) and the wound cord on the top. In some embodiments, the location of the cg of the top is closer to a tip of the top than to a top of the top, and in some embodiments, the location of the cg of the top is closer to a top of a body portion of the top than to the tip, and in some embodiments, the location of the cg of the top is located closer to the tip of the top than to the top of the top and closer to the top of the body portion than to the tip. In some embodiments, a slot is provided in which to wind a portion of a cord used to launch the top, where the slot is located at or near the cg of the top. 
         [0003]    In an embodiment of the invention, a toy top comprises a body portion including a circumferential slot thereabout adapted to receive wound therein a portion of a cord used to launch the top. The top in this embodiment is configured so that the slot is at or adjacent the cg of the top, e.g., the slot may extend about the cg radially aligned with or slightly offset from the cg. A top portion may extend from the body portion, with the cord being attached to the top portion and the cg of the top being as described above. 
         [0004]    According to an embodiment of the invention, a toy top, adapted to spin about a spin axis, comprises a body portion, a tip, a top portion and a cord. The tip (e.g., a ball) at a bottom of the body portion is rotatably attached relative to the body portion and is adapted to rotate together with or independently of with the body portion. The body portion is radially symmetrical and axially non-symmetrical with respect to the spin axis. The top portion extends beyond a top of the body portion, and the cord extends from the top portion, spaced from the top of the body portion. The cord is attached to the top portion and the top portion is attached rotatably or non-rotatably relative to the body portion, so that at least the body portion is rotatable relative to the cord. (The terms rotatable (rotatably) and non-rotatable (non-rotatably) are used in a broad sense and can encompass any relative rotation or rotary motion between or among concerned parts.) The top includes a cg that is located within the body portion on the spin axis closer to the tip of the top than to the top of the top portion, and closer to the top of the body portion than to the tip. The body portion includes a slot circumferentially extending thereabout at or near the cg, the slot being configured to receive therein a plurality of turns of the cord. 
         [0005]    In some embodiments, a weapon is attached to the body portion, and players may battle their tops using respective weapons. The weapon is at least radially symmetrical with respect to the spin axis, and the top with attached weapon has a cg as described above. The weapon may be of one piece or a plurality of pieces and may be detachably or non-detachably connected to the body portion. 
         [0006]    In some embodiments, the top portion may be non-rotatably attached relative to the body portion and the cord rotatably attached relative to the top portion. In some embodiments, the top portion is attached rotatable relative to the body portion and the cord may be rotatably or non-rotatably attached relative to the top portion. In either case, the cord is attached so as not to spin with the top when the top is spinning on a spin surface. 
         [0007]    In some embodiments, the body portion includes an interior shaft portion extending within the body portion, and the top portion described above includes an exterior shaft portion extending from the body portion. A collar may be attached to the top of the external shaft portion and the cord attached to the collar. The shaft portions may be rotatably or non-rotatably attached relative to each other. Where the shall portions are non-rotatably attached, the cord is rotatably attached to the external shall portion. The tip may comprise a ball rotatably attached to the bottom of the internal shaft portion. 
         [0008]    In some embodiments, a headpiece may be attached to the external shaft portion either to rotate relative to the shaft portion or with it. The headpiece may include graphics, coloring or other decoration to provide a desired visual effect as the top spins. Movement of the headpiece can impart animation effects to a spinning top. 
         [0009]    In some embodiments, the cg of the top is located a first distance from the top of the top portion and a second distance from the tip, where the ratio of the first distance to the second distance is greater than 1. In one embodiment, the ratio is about 1.4:1. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    The invention is illustrated in the figures of the accompanying drawings, which are meant to be exemplary and not limiting, and in which like references are intended to refer to like or corresponding parts. 
           [0011]      FIG. 1  is perspective view from the top of a toy top according to an embodiment of the invention, including a weapon attached to the top, a cord attached to the top wound in a slot of the top, and without a headpiece. 
           [0012]      FIG. 2  is a side view of the top depicted in  FIG. 1  without the weapon and cord but with the headpiece. 
           [0013]      FIG. 3  is an axial cross-section view of the top depicted in  FIG. 2  showing the cord unwound from the slot. 
           [0014]      FIG. 4  is a perspective view from the bottom of the top of  FIG. 1 , without the headpiece and showing the cord unwound from the slot. 
           [0015]      FIG. 5  is a perspective view from the top of the toy top depicted hi  FIG. 1  ready to be launched, showing a person&#39;s hand gripping the top with the cord wound in the slot and looped about the person&#39;s wrist. 
           [0016]      FIG. 6  is a side view of the top depicted in  FIG. 1 , without a headpiece and after launch thereof spinning on a spin surface with the cord being held by a person&#39;s hand. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    In the embodiment depicted in the drawings, toy top  10  comprises a body portion  12 , including a circumferentially extending slot  14  therein, a tip  16  attached at the bottom  18  of the body portion  12  and an external shaft portion  20  extending beyond the top  22  of the body portion  12 . A collar  24  is attached at the top of the external shall portion  20 , and a cord  26  is attached to the collar  24 . As shown in the  FIG. 3  cross-sectional view, the body portion  12  includes a hollow region  28 , and an internal shaft portion  30  extends with the body portion  12  from the tip  16  to top  22  of the body portion  12 . The external and internal shall portions  20  and  30  may be solid or hollow. In the illustrated embodiments, the shaft portions  20  and  30  are solid. 
         [0018]    As described in more detail below, the tip  16  is rotatably attached relative to the body portion  12  and the external shaft portion  20  is non-rotatably attached relative to the body portion  12 . The external shaft portion  20  rotates with the top  10  when the top  10  is spinning after launch onto a surface  32  ( FIG. 6 ) such as a floor, sidewalk, pavement, table top, etc. 
         [0019]    As depicted in FIGS.  1  and  3 - 6 , the top  10  may include a weapon  34  that may be detachably or non-detachably mounted to the body portion  12 . The weapon  34  assists in locating the cg of the top, and different weapons may provide different cg&#39;s, e.g., at ratios in the range of 1.4:1 to 1.5:1 of the first and second distances described above. In one embodiment, the weapon  34  assists in locating the cg for the top at a 1.4:1 ratio of the first and second distances described above. The weapon  34  may interact with other spinning tops as part of a game or competition. The weapon  34  extends circumferentially around the body portion  12  and snaps into a circumferentially extending groove  36  ( FIG. 3 ) for easy attachment and detachment.  FIG. 2  shows an alternative embodiment of the top  10  without the weapon  34 . In this embodiment, the cg is as described above. In an embodiment where the weapon  34  is detachable, one or more weapons (not shown) may be attached to the top  10  in place of or in addition to weapon  34  depicted in the drawings. 
         [0020]    The top  10  has a spin axis  38 , and the body portion  12  is radially symmetrical and axially non-symmetrical relative to the spin axis  38 . The weapon  34  is also symmetric relative to the spin axis  38 . 
         [0021]    The body portion  12  is generally of frustro-conical shape, but may have other radially symmetrical shapes. Referring to  FIG. 3 , the internal shaft portion  30  is non-rotatably attached to the body portion  12  at or adjacent the bottom  18  thereof. The top  22  of the body portion  12  includes an inner annular recess  40  ( FIG. 3 ) that receives a generally disc-shaped plate  42  therein. The plate  42  has a central hole  44  in a boss  46  through which the external shaft portion  20  passes. The plate  42  is attached to the top  22  of the body portion  12  by screws  48 . Beneath the plate  42 , in an outer annular recess  50 , is a toroidal weight  52 . The internal shaft portion  30  is fixed relative to the exterior shaft portion  20 . Both the internal shaft portion  30  and the exterior shaft portion  20  are held non-rotatable relative to the body portion  12 . 
         [0022]    The bottom end  56  of the internal shaft portion  30  includes a recess  58  in which is received and rotatably attached the tip  16 . In this embodiment, the recess  58  is hemispherical and the tip  16  is a ball, where the diameter of the ball is slightly less than the diameter of the internal shaft portion  30  and the depth of the recess  58  is slightly less that the diameter of the ball, which provides for the ball to be rotatably captivated protruding slightly from the internal shaft portion so as to be capable of rotating relative thereto. 
         [0023]    In the illustrated embodiments, the external shaft portion  20  is non-rotatably attached relative to the body portion  12 , as mentioned above. The cord is rotatably attached relative to the external shaft portion. For example, the cord may be rotatably attached to a collar which may be rotatably or non-rotatably attached to the external shaft portion, or the cord may be non-rotatably attached to the collar and the collar rotatably attached to external shaft portion. 
         [0024]    The external shaft portion  20  may be covered by a shaft cover, or a headpiece  62  may be attached to the shaft portion. Depending upon desired effects, the headpiece can be rotatably or non-rotatably attached to the external shaft portion  20 . In one embodiment, the headpiece  62  is loosely mounted to the shaft portion  20  to be able to rotate relative thereto. The headpiece  62  may include graphics, coloring or other decoration to provide a desired visual effect as the top  10  spins. Movement of the headpiece  62  can impart animation effects to a spinning top. For example, the headpiece may portray a face whose appearance or expression changes as the headpiece  62  spins. In one embodiment, the headpiece  62  is of ring-like configuration ( FIG. 5 ) and includes a hole which loosely receives the external shaft portion  20 . In another embodiment, the headpiece  62  may be a disc ( FIG. 3 ) with a hole that loosely receives the external shaft portion  20 . The headpiece  62  may take other configurations, e.g., disc-like, spherical, conical, frustro-conical, tubular, and still other configurations. 
         [0025]    A collar  24  is attached to the free or upper end of the external shaft portion  20  with the free end of the collar extending past the upper end of the shaft portion  20 . The collar  24  includes a hole  66  above the top of the external shaft portion  20  through which the cord  26  is passed and then knotted to attach the cord to the collar. The free end of the cord  26  includes a loop  68  formed, e.g., using a slipknot similar to the free end of a yo-yo cord, and adapted to be looped about the wrist of a person&#39;s hand, as illustrated in  FIG. 5 . In the launching configuration of the top illustrated in  FIG. 5 , the cord  26  as it runs from the collar  24  is wound into slot  14  until almost all of the cord is wound except for a small length sufficient to allow a person to insert his or her wrist into the loop  68 . Alter launch of the top, as depicted in  FIG. 6 , a person holds the cord between his or her thumb and first finger with the free end of the cord looped about the person&#39;s wrist. 
         [0026]    In summary, as described above, in the illustrated embodiment, the internal shaft portion  30  is fixed relative to the body portion  12  and the tip is rotatable relative to the internal shaft portion  30 , so that the body portion and the internal shaft portion may rotate independently of the tip. The external shaft portion  20  is also fixed relative to the body portion and the internal shaft portion. The collar  24  is rotatably attached to the external shaft portion  20  so that the body portion  12 , the external shaft portion  20 , and the collar  24  may rotate together or independently of each other. 
         [0027]    As mentioned above, the headpiece  62  is loosely mounted to the external shaft portion  20  between the boss  46  and the collar  24 . Since the boss  46  and the external shaft portion  20  rotate with the body portion  12 , and since the headpiece  62  is in contact with the boss  46  and the external shaft portion  20 , the headpiece  62  can rotate under influence of them when the body portion  12  is rotating. 
         [0028]    The body portion  12 , including the hollow region  28 , the weapon  34 , the internal shaft portion  30 , the disc-shaped plate  42 , the toroidal weight  52 , the external shaft portion  20 , the headpiece  62 , the collar  24 , and the tip  16  provide the top  10  with the desired weight (mass) and weight (mass) distribution, and a cg or centroid  70  ( FIG. 3 ) that is located on the spin axis  38  at or adjacent the slot  14 , as described above. The sizes (configurations), locations, and weights of these parts are selected to provide the desired weight and weight distribution. Also, the materials of some parts are selected not only in consideration of the above, but also for wear, durability and frictional considerations. For example: the tip  16  may be made of steel or some other hard, low friction, durable material. This allows the top  10  to be easily moved or guided, even on an inclined surface, by pulling the cord  26 , in a desired direction. The shaft portions  20 ,  30 , the plate  42 , the headpiece  62  and the collar  24  may be made of suitable metal, e.g., brass or copper; the toroidal weight  52  may be made of steel or zinc, and the body portion  12  and the plate  42  may be made of hard, durable plastic, e.g., ABS. 
         [0029]    The location of the cg  70  is illustrated in  FIG. 3 , and in one embodiment is at a distance “a” from the top of the collar  24  and at a distance “b” from the bottom of the tip  16 . In the embodiment illustrated in the drawings, it has been found that locating the cg on the spin axis closer to the top of the body portion than to the tip of the top, and closer to the tip of the top than to the top of the collar improves top performance. The spin time and angular velocity of a top can be increased or optimized when the inertia, angular momentum and centroid of the top are considered. For example, the inertia of a body, I, is I=M A (R A ) 2 +M B (R B ) 2 +M C (R C ) 2 + . . . , i.e., the sum of M A (R A ) 2 +M B (R B ) 2 +M C (R C ) 2 + . . . , which represents the sum of the MR 2  values for all particles of the body. The quantity sum of M A (R A ) 2 +M B (R B   2 +M C (R C ) 2 + . . . depends on the mass and its distribution and is taken as a measure of the moment of inertia of the body about the rotating axis. R A  is the distance of a particle with mass M A  to the rotating axis, etc. (Tom. D.,  Advanced Physics for Hong Kong - Volume I: Materials and Mechanics,  John Murry, pp. 165-184, 1992.) The angular momentum, L, of a top is L=Iω, where ω is the angular velocity. For two objects rotating at the same angular velocity, the object with the greater moment of inertia will have the larger kinetic energy, E, according to the equation E=½MR 2 ω 2 +½Mν 2 , where M is the mass, ω is the angular velocity and ν is the linear velocity. More kinetic energy can increase spin time. The cg is a geometric property of any object, and is the average location of the weight of an object. If the object has a line (or plane) of symmetry, the cg lies on the line of symmetry. For a solid block of uniform material, the center of gravity is simply at the average location of the physical dimensions. For a rectangular block, 50(L)*20(W)*10(H), the center of gravity is at the point of (25, 10, 5). (Ref: Glenn Research Center, National Aeronautics and Space Administration, 2006, http://www.grc-nasa.gov/www/k-12/airplane/cg.html). For example, the cg of top  10  is located on the spin axis. 
         [0030]    In one embodiment, the top  10  has the following dimensions: height, 70 mm; largest diameter of the body portion 45 mm; height of the body portion 38.2 mm; height of the external shaft portion 29 mm; The distance from the center of gravity to the top of the body portion is 12.8 mm; and total weight (without cord), 90 g. In this embodiment, the tip  16 , the shaft portions  20 ,  30 , the body portion  12 , the plate  42 , the collar  24  and the toroidal weight  48  may be made of the materials identified above. In such an embodiment, the distance “a” is 41 mm, the distance “b” is 29 mm, and the ratio a/b is 1.41:1. In the equation I=MR 2  (where I is the inertia of the top and M is the mass), the moment of inertia of the top at the cg along the spin axis is 4,675,000 gmm 2 . An a/b ratio of about 1.4:1 where the cg is at or adjacent slot has been found to provide the top  10  with improved angular velocity and kinetic energy, which improve the spin time of a top. 
         [0031]    The cord  26  may be made of any suitable material such as nylon, cotton, etc. The depth of the slot  14  is sufficient to allow the cord to be wound multiple times therein, where the number of winds is selected to provide an increased or optimized angular velocity to the top when properly launched. 
         [0032]    The top  10  is launched and operated as illustrated in  FIGS. 5 and 6 . After the cord  26  is wound in slot  14 , top  10  can be gripped by a person&#39;s hand as illustrated in  FIG. 5  with the person&#39;s wrist in the loop  68  of the cord. The top  10  may then be released or thrown downward while the free end of the cord  26  is retained by the person&#39;s wrist. When released or thrown downward, the action of the cord  26  unwinding from the slot  14  will impart an angular velocity to the top. The cord  26  should be fully unwound when the top reaches the surface on which it will spin, e.g., a floor, platform, or tabletop, etc. With the cord  26  fully unwound and the top spinning on a spin surface  32 , the cord may be tugged or led to move or guide the top in any desired direction. Persons may play competitive games using the tops, e.g., longest spin time, moving up the steepest incline, negotiating obstacles, races and battles, e.g., using weapons  34  to knock an opposing person&#39;s top down. 
         [0033]    While the invention has been described and illustrated in connection with preferred embodiments, many variations and modifications as will be evident to those skilled in this art may be made without departing from the spirit and scope of the invention as defined by the claims, and the invention is thus not to be limited to the precise details of methodology or construction set forth above as such variations and modifications are intended to be included within the scope of the invention as defined by the claims.