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[0001]     The application is a divisional of application Ser. No. 10/756,816, filed Jan. 13, 2004, the disclosure of which is incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a self-locking strap assembly. In particular, the present invention relates to strap assemblies for restraining individuals, such as disposable handcuffs.  
         [0003]     Disposable handcuffs are used by police officers, security guards and the like for temporarily restraining individuals. Disposable handcuffs, due to their size and weight, are useful in various circumstances including multiple arrest situations and prisoner transfers. Additionally, disposable handcuffs can be made out of a plastic material which prevents the activation of metal detectors in airports, courthouses, prisons and other protected structures.  
         [0004]     Current disposable handcuffs are close variations to a traditional cable tie. Generally, a cable tie is made of a hard plastic material that includes an elongated strap and a locking head. Upon insertion of the elongated strap within the locking head, the locking head includes teeth to prevent withdrawal of the strap such that an individual cannot release the strap from the locking head. One drawback of using cable tie arrangements as a restraining device is that the arrangements can cause excessive damage to a person&#39;s wrist during restraint. The hard, plastic material of the elongated strap and locking head can cut into and otherwise damage a person&#39;s wrist. Thus, a self-locking strap assembly is needed that provides adequate restraint of individuals while preventing excessive damage to a person&#39;s wrist during restraint.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention relates to a self-locking strap assembly. In one aspect, the assembly includes a buckle having an outer concave surface and a passageway. A strap is secured to the buckle at a first position and is adapted to be inserted into the passageway at a second position. A retainer is coupled to the buckle and adapted to engage the strap such that movement in one direction of the strap in the passageway relative to the buckle is inhibited. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is a top isometric view of a strap assembly.  
         [0007]      FIG. 2  is a bottom isometric view of a strap assembly.  
         [0008]      FIG. 3  is a side view of a strap assembly.  
         [0009]      FIG. 4  is a top view of a strap assembly.  
         [0010]      FIG. 5  is a side view of a strap assembly.  
         [0011]      FIG. 6  is a top isometric view of a housing element.  
         [0012]      FIG. 7  is a top view of a housing element.  
         [0013]      FIG. 8  is a side view of a housing element.  
         [0014]      FIG. 9  is a top isometric view of a housing element.  
         [0015]      FIG. 10  is a top view of a housing element.  
         [0016]      FIG. 11  is a side view of a housing element.  
         [0017]      FIG. 12  is a top isometric view of a retainer.  
         [0018]      FIG. 13  is a top isometric view of a strap.  
         [0019]      FIG. 14 a  top isometric view of a separator.  
         [0020]      FIG. 15  is an alternative embodiment of an assembly. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]      FIGS. 1-5  illustrate an embodiment of the present invention. Assembly  10  includes a buckle  12  that is curved on one surface to engage a person&#39;s body such as a wrist or ankle, while a soft strap  14  wraps around a person&#39;s wrist and is secured at the buckle  12  near both ends. One end of the soft strap  14  can be permanently secured to the buckle  12 , while the other end of the strap  14  passes through the buckle  12  and is held by a retainer that engages the strap  14 . In the embodiment illustrated, strap  14  includes a first end  16  having a loop secured to one end of the buckle  12 . A free end  18  of strap  14  is inserted into a passageway in buckle  12 , where a retainer, described below, engages the strap  14  through the passageway in one direction. If desired, a separator  20  can be used to form multiple loops in strap  14  before inserting free end  18  into buckle  12 .  
         [0022]     With further reference to  FIGS. 6-11 , buckle  12  can be formed from a two-part housing including a first housing element  22  and a second housing element  24 . In one embodiment, buckle  12  can be made of a plastic material. As illustrated in  FIGS. 6-8 , housing element  22  includes a lower concave surface  26 . The lower concave surface  26  is adapted to engage a person&#39;s wrist or ankle in order to minimize injury during restraint. Additionally, housing element  22  further includes a shaft  28  that receives the loop of first end  16  of strap  14  and a passageway  30  to receive free end  18  of strap  14 . A cavity  32  within housing element  22  can receive a suitable retainer, described below, for engaging strap  14  to prevent movement of free end  18  back through passageway  30  after insertion. Housing element  22  also includes a first pin  34  and a second pin  36  for engaging and securing housing element  22  to housing element  24 . In order to aid an operator in grasping buckle  12  and pulling strap  14  to engage the retainer, housing element  22  includes a concave side wall  38  and a plurality of ribs  40 .  
         [0023]     With reference to  FIGS. 9-11 , housing element  24  includes a lower concave surface  42  similar to lower concave  26  of housing element  22 . The lower concave surface  42  is adapted to engage a person&#39;s wrist or ankle in order to minimize injury during restraint. Housing element  24  also includes a shaft  44  that receives the loop of first end  16  of strap  14  and a passageway  46  to receive free end  18  of strap  14 . A cavity  48 , which is aligned with cavity  32  of housing element  22 , receives a retainer for engaging strap  14  to prevent movement of free end  18  back through passageway  46  after insertion. Housing element also includes a first aperture  50  and a second aperture  52  for receiving first pin  34  and second pin  36  of housing element  22 , respectively. Similar to housing element  22 , in order to aid an operator in grasping buckle  12  and pulling strap  14  to engage the retainer, housing element  24  includes a concave side wall  54  and a plurality of ribs  56 .  
         [0024]      FIG. 12  illustrates a retainer  58  that is housed by buckle  12  in cavities  32  and  48 . Retainer  58  can be made out of a plastic or other suitable material in accordance with the present invention. Retainer  58  includes a first pointed barb  60  and a second pointed barb  62 . Retainer  58  is slightly pivotable in cavities  32  and  48  to allow strap  14  to slide through passageways  30  and  46 . Movement of the strap  14  in an opposite direction causes the pointed ends of barbs  60  and  62  to engage strap  14 , which inhibits further movement of the strap  14  in the reverse direction. Retainer  58  can also include an over travel stop  64  that limits rotation of retainer  58  within cavities  32  and  48 .  
         [0025]      FIG. 13  illustrates strap  14  including first end  16  and second end  18 . As discussed above, first end  16  includes a loop that is received by buckle  12  that can be sewn or heat staked to form the loop. In accordance with a further aspect of the present invention, second end  18  may be heat staked. Heat staking a portion of second end  18  allows end  18  to be inserted partially into buckle  12  and subsequently removed. The heat staked portion of end  18  is prevented from being engaged by barbs  60  and  62  of retainer  58  and also provides a stiffer portion to be inserted into passageways  30  and  46 . In addition, strap  14  has a width substantially greater than its thickness so as to be flexible and increase the surface area of contact with a person&#39;s wrist in order to minimize injury thereto and allow the strap to be folded over for easier packaging and carrying of assembly  10 . Suitable materials that can be used for strap  14  include nylon and woven polypropylene.  
         [0026]      FIG. 14  illustrates an isometric view of separator  20 . Separator  20  includes apertures  66  and  68  for receiving strap  14 . Using aperture  66  and  68 , multiple loops within strap  14  can be formed by inserting strap  14  into each of the apertures  66  and  68 . For example, one loop can be used to secure a first wrist of an individual and one loop can be used to secure a second wrist of the individual. Additionally, multiple assemblies  10  can be looped together using multiple loops in each of the straps  14  of the assemblies  10 .  
         [0027]     As appreciated by those skilled in the art, other variations of the embodiment described above can be used in accordance with the present invention. For example,  FIG. 15  illustrates an alternative embodiment of an assembly  70  including a buckle  72 , strap  74  and retainer  76 . In this embodiment, the retainer  76  is a metal, serrated blade including a plurality of teeth to engage strap  14  upon insertion into buckle  72 .  
         [0028]     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Summary:
The present invention relates to a self-locking strap assembly. The assembly includes a buckle having an outer concave surface and a passageway. A strap is secured to the buckle at a first position and is adapted to be inserted into the passageway at a second position. A retainer is coupled to the buckle and adapted to engage the strap such that movement in one direction of the strap in the passageway relative to the buckle is inhibited.