Patent Publication Number: US-2005118926-A1

Title: Construction toys with dimple-containing magnet

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims priority to U.S. Provisional Patent Application Ser. No. 60/512,952 filed Oct. 21, 2003 entitled “Dimple Containing Magnet” which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      This invention relates to magnets and, in particular, to toys and toy construction sets utilizing magnets.  
     BACKGROUND OF THE INVENTION  
      Magnets exhibit such interesting properties and permit such easy “construction” of structures containing them that they have long been used as toys and have long been incorporated in toys. The relatively recent availability of inexpensive, extremely strong rare earth magnets has enabled design of improved toy magnets and toys containing magnets. Among such toys are building components including steel spheres or spherical magnets and “spars,” elongated structures containing magnets in their ends for magnetic attachment to other such spars or other structures such as spheres.  
      Contact between a sphere and a conventional flat magnet surface is a point contact that provides essentially no lateral stability. As a result, construction toy spars that have flat-end magnets exhibit no lateral stability when magnetically connected to a spherical surface, therefore often requiring additional spars for lateral support.  FIG. 1  is a side view of an end of a spar  8  holding a flat-end magnet  10  contacting a sphere  12  in such a prior art structure that achieves one-point contact.  FIG. 2  illustrates another prior art structure in which a spar  8  holds a flat-end magnet  14  penetrated by a small hole  16  so that contact with a sphere  12  will be between the spherical surface and the rim  18  of the spar magnet  14  hole  16 .  
      However, since a magnet&#39;s performance (other factors being equal) is a function of its geometry and volume, such magnets penetrated by a hole sacrifice function. A through hole in the face of a magnet results in an air path through the magnet, which reduces its magnetic power, and a hole removes magnet material, which also reduces magnetic power. These considerations cause it to be desirable to use a smaller hole, but the smaller the hole (and therefore the smaller the diameter of the rim that contacts a steel sphere) results in reduced lateral stability and reduced strength. In addition, a small through hole traps contaminants such as oils and grease during the manufacturing process that are difficult to remove by conventional means. Furthermore, if not removed, these contaminants migrate out of the hole in the magnet during the application of a protective coating (such as nickel plating) resulting in poor adhesion of the protective coating, which then flakes off. Without a protective coating a rare earth magnet will corrode or rust, which reduces the magnet&#39;s performance.  
     SUMMARY OF THE INVENTION  
      A dimple in the face of a magnet, such as a magnet affixed to a spar end, provides a strong, laterally stable magnetic connection with a sphere, particularly if the rim or intersection between the surface of the recess and the face of the magnet is a circle. Such a dimple or recess, as compared to a hole through an otherwise comparable magnet, provides greater magnetic strength by eliminating the air path through the magnet and by avoiding significant loss of magnetic material to the hole and is easily cleaned of contaminants. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side view of a prior art flat end magnet contacting a sphere.  
       FIG. 2  is a side view similar to  FIG. 1  but showing a flat end magnet with a through hole contacting a sphere.  
       FIG. 3  is a side view of a dimple-containing magnet of this invention positioned near a sphere.  
       FIG. 4 , is another view of the dimple-containing magnet of this invention shown in  FIG. 3  positioned near a larger diameter sphere.  
       FIG. 5  is a side view of a construction toy spar containing two dimple-containing magnets of this invention and a sphere of the same radius as the dimple.  
       FIG. 6  is an alternative embodiment of the dimple-containing magnet of this invention having a dimple that is not defined by a spherical surface.  
       FIG. 7  is a Y-connector construction toy component of this invention.  
       FIG. 8  is an X-connector construction toy component of this invention.  
       FIG. 9  is an illustrative assembly of construction toy components of this invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       FIGS. 3-6  illustrate alternative embodiments of the dimple-containing magnet of this invention, shown mounted in another object, which may be a toy component such as a construction toy spar or any other component desired.  
       FIG. 3  illustrates a dimple  20  in a magnet  22  in a toy component  24  positioned near a sphere having a radius comparable to the radius of the dimple.  FIG. 4  shows a like spar  24  and magnet  22  but having a dimple  26  with a smaller radius “r” than the radius “R” of a sphere  28 .  
       FIG. 5  illustrates that by forming a dimple  34  as a concave surface  35  with a radius “r” exactly matching the radius “r” of the surface  36  of a steel sphere  38  with which the dimple-containing magnet is used, contact will be achieved across the entire dimple  34 , providing substantial lateral support and maximizing the magnetic connection. If, on the other hand, a dimple is defined by a semi-spherical surface having a slightly shorter radius than the radius of the steel sphere, then contact will occur between the two at the rim of the magnet dimple, thereby maximizing lateral stability. Such a dimple having a slightly shorter radius semi-spherical surface ensures highly stable contact with spheres of approximately the same size while not requiring exact identity of sphere size from one sphere to another. Ring contact also ensures minor defects (protrusions) on the sphere do not significantly affect performance as would be the case for exactly matching magnet dimple and sphere radii, which could result in point contact verses ring contact.  FIG. 5  further illustrates this invention in a magnet  22  having a dimple  34  that fully occupies the end  23  of the magnet  22 , thereby providing the largest dimple area possible for this magnet.  
      In  FIG. 5 , the radius r of the dimple is equal to the radius r of the sphere  36 , theoretically enabling contact between the entire dimple surface  35  and the surface  38  of the sphere  36 .  
      A somewhat exaggerated-for-clarity example of a smaller radius dimple  26  and larger sphere  28  is illustrated in  FIG. 4 , where the magnet  22  dimple  26  has a shorter radius r than the longer radius R of the sphere  28 . As may be seen in  FIG. 4 , a portion of the surface  30  of the sphere  28  is received within the dimple  26 , but there is contact between the sphere surface  30  and the magnet only at the rim  32  of the dimple  26 .  
      Incorporation of such dimples in the ends of magnets removes relatively little magnetic material and avoids the pole-to-pole air path introduced by a through hole as illustrated in  FIG. 2 .  
      As will be readily appreciated by study of the figures and consideration of the information set forth above, dimples usable to obtain the benefits of this invention can have shapes other than the semi-spherical shapes illustrated in the accompanying figures and described above, although the semi-spherical shape will typically be optimal. For instance, the dimple could have a shape of the inside of a cone or a truncated cone like the truncated conical shape  50  of the dimple  52  illustrated in  FIG. 6 . Numerous other shapes would likewise be possible, provided that there are at least three reasonably separated points of contact between the sphere and the magnet. For instance, a dimple having a shell-like series of scallops would provide a series of peripheral contacts establishing a stable magnet to sphere connection. As should likewise be appreciated, while most of the discussion above assumes that the spar end will be a magnet and the sphere simple steel, the components could be reversed by using a spherical magnet and a ferrous metal spar or spar end.  
      As will also be apparent to those skilled in the art of magnet manufacture, the dimples of this invention can be formed in magnets or ferrous metal structures by a variety of methods including conventional machining and metal-forming methods.  
      Spars or other parts containing magnets with dimples can contain one dimple-containing magnet  22 , as illustrated in  FIG. 3 , two magnets  22 , as illustrated in  FIG. 5 , three magnets  22  as illustrated in  FIG. 7  showing a Y-connector  60 , four magnets  22  as illustrated in  FIG. 8  showing an X-connector  70 . Other numbers of dimple-containing magnets are also possible.  
      Components containing dimple-containing magnets in accordance with this invention can be assembled in an endless variety of ways with numerous other ferromagnetic or ferromagnetic-containing components. For instance, such components can be assembled as shown in  FIG. 9  with spars  24  resting on disks  29  and supporting spheres  28  that in turn hold spars  25  that contact spheres  28  at one of their ends and a ring  31  at the other of their ends.  
      These and other variations of this invention are all within the spirit and scope of this invention, the foregoing description and accompanying drawings, and the following claims.