Abstract:
An adjustable shoulder strap attachment assembly is disclosed, as are methods for adjustably attaching shoulder straps to a backpack frame. The backpack frame has a pair of generally vertically-oriented tracks. Each strap has a cam-fastener with at least one dimension greater than the width of one of the tracks. To secure a strap to the backpack frame, the cam-fastener is inserted into the track and rotated into its use position. A desired vertical position of the strap is selected, and the strap is secured by using hook-and-loop fastener between the backpack frame and the strap.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to U.S. patent application Ser. No. 13/183,767, filed Jul. 15, 2011; U.S. patent application Ser. No. 13/549,289, filed Jul. 13, 2012; and U.S. application Ser. No. 13/856,594, filed Apr. 4, 2013. All of those applications are incorporated by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    In general, the invention relates to backpack frames, and to strap systems for backpack frames. 
         [0004]    2. Description of Related Art 
         [0005]    Shoulder straps are a key element in distributing the load of a backpack to its wearer. In day packs and smaller backpacks without a frame, the shoulder straps may be sewn directly to the backpack at fixed points, although these arrangements usually include buckles and fittings to change the length of the straps. 
         [0006]    Backpack frames help to support the load in a backpack and to distribute that load more evenly to the wear&#39;s body. Many frames include mechanisms by which shoulder straps can be attached at different heights and positions, in order to accommodate wearers of different builds. In a typical mechanism, a clip is attached to each end of each strap, and the frame provides multiple points to which each clip may be attached. 
         [0007]    A more continuously adjustable mechanism for attaching straps would be a help in allowing users of different body sizes to comfortably use a backpack and backpack frame. 
       SUMMARY OF THE INVENTION 
       [0008]    One aspect of the invention relates to an adjustable strap and frame combination for a backpack. The backpack frame has left and right generally vertically-extending tracks spaced from one another. An expanse of one part of hook-and-loop fastener is provided proximate to the tracks. Left and right straps attach to the backpack frame. Each of the straps includes a cam-fastener and complementary hook-and-loop fastener. The cam-fastener has a projecting portion with at least one dimension greater than a width of one of the tracks, such that the cam-fastener can be pivoted into position to secure the cam-fastener and its connected strap slideably in one of the tracks. The complementary hook-and-loop fastener of the straps is positioned to engage the hook-and-loop fastener of the backpack frame to fix the vertical position of the straps. In some embodiments, the straps include lower portions that connect with a waist belt. The waist belt is adapted to engage lower portions of the backpack frame. 
         [0009]    In embodiments according to this aspect of the invention, the cam-fastener typically includes a base and a post or neck connected between the base and the projecting portion. The projecting portion may, for example, be a bar with a length greater than a width of one of the tracks. 
         [0010]    Another aspect of the invention relates to a method of adjustably securing backpack straps to a frame. The method comprises engaging a cam-fastener connected to a strap in a generally vertically-extending track or slot of a backpack frame. The method also comprises sliding the engaged cam-fastener along the track so that the strap is in a desired vertical position, and securing the strap in the frame using hook-and-loop fastener. 
         [0011]    These and other aspects, features, and advantages of the invention will be set forth below in more detail. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0012]    The invention will be described with respect to the following drawing figures, in which like numerals represent like elements throughout the figures, and in which: 
           [0013]      FIG. 1  is a perspective view of a backpack frame with waist belt and left and right strap assemblies; 
           [0014]      FIG. 2  is an elevational view of the backpack frame in isolation, illustrating the side of the frame that faces the strap assemblies; 
           [0015]      FIG. 3  is an exploded perspective view of the backpack and frame assembly of  FIG. 1 ; 
           [0016]      FIGS. 4 and 5  are respective sequential elevational views of the frame, illustrating the attachment of one of the strap assemblies; 
           [0017]      FIG. 6  is a perspective view of the other side of the frame, illustrating the attachment of one of the strap assemblies; and 
           [0018]      FIG. 7  is a perspective view of the frame, illustrating various vertical positions in which a strap assembly may be placed in connection with the frame. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  is a perspective view of a backpack frame, generally indicated at  10 , with two shoulder straps  12 ,  14  and a waist belt  16  installed, and  FIG. 2  is an elevational view of the backpack frame  10  in isolation. The backpack frame  10  illustrated in these figures and others is one of the frames described in U.S. Patent Application Publication No. 2013/0221051, the entire contents of which are incorporated by reference in their entirety. This frame  10  is a unitary, resin-impregnated structure made of carbon fiber, although the general construction of the frame is not critical in all embodiments of the invention, so long as the frame in question has the basic features described here. 
         [0020]    Relevant to the process of attaching and adjusting the shoulder straps  12 ,  14 , the frame  10  has two generally vertical tracks  18 ,  20  that are sloped slightly inwardly as they extend downwardly. The tracks  18 ,  20  are fully open and go through the thickness of the frame  10 . These tracks  18 ,  20  provide adjustable points of connection to the frame  10  for the two shoulder straps  12 ,  14 , as shown in  FIG. 1 . 
         [0021]    As shown in  FIG. 1  and in the exploded perspective view of  FIG. 3 , each shoulder strap  12 ,  14  has a cam-fastener  22  sewn into it. The top of the cam-fastener  22  is a generally rectangular bar  24  that, when installed in each strap  12 ,  14  extends parallel to the width of the strap  12 ,  14 . The bar  24  is also longer than the width of the tracks  18 ,  20 . The rectangular bar  24  is connected at its center to a post or neck  26 , which is, in turn, connected to a base  28 . The base  28  of the cam-fastener  22  is at least about as wide as the bar  24  itself, and in the illustrated embodiment, is a round disc. In general, the cam-fastener  22  should be made of a lightweight but rigid material, such as ABS plastic [CORRECT?], such that it can sustain the loads carried by the backpack. In other embodiments, the projecting portion of the cam-fastener  22  need not be a bar  24 ; rather, any non-uniform shape with at least one dimension wider than the width of the tracks  18 ,  20 . The size and area of the base  28  and rectangular bar  24  are sufficient to distribute the load somewhat so as to avoid causing failure of the stitching or other materials in the straps  12 ,  14  or a failure of the area around the tracks  18 ,  20 . Typically, the base  28  is sewn or otherwise fixed into its strap  12 ,  14 , for example, with adhesives. 
         [0022]    The process of connecting the straps  12 ,  14  to the frame  10  is illustrated in the sequential elevational views of  FIGS. 4-5 . To connect one of the straps  12 ,  14  to the frame  10 , the user places the strap generally perpendicular to its use position, so that the length of the rectangular bar  24  is parallel with the track  18 ,  20 , and inserts the bar  24  through the track  18 ,  20  before rotating the strap  12 ,  14  upright into its use position, as illustrated in  FIG. 5 . In the use position illustrated in  FIG. 1 , the rectangular bar  24  is perpendicular to the track  18 ,  20  so that it cannot pull out of the track  18 ,  20 . 
         [0023]      FIG. 6  is a perspective view of the frame  10  and one strap  14 , illustrating the opposite side of the frame  10 . The cam-fastener  22  provides a sliding connection between the strap  12 ,  14  and the frame  10  and prevents pull out in the normal direction, i.e., the direction perpendicular to the frame. In order to keep the straps  12 ,  14  in a particular vertical position along the tracks  18 ,  20 , the frame  10  and straps  12 ,  14  use complementary patches of hook-and-loop fastener. More specifically, each strap  12 ,  14  has a patch  30  of hook-and-loop fastener below the cam-fastener  22 . A complementary expanse  32  of hook-and-loop fastener is provided in the center of the frame  10 , below the tracks  18 ,  20  on the side of the frame  10  that faces the straps  12 ,  14 . The present inventors have found that when fully engaged, hook-and-loop fastener has sufficient strength in shear to fix the position of the straps  12 ,  14  vertically. Moreover, by providing a relatively long swath of hook-and-loop fastener, the user can adjust the vertical position of the straps  12 ,  14  continuously, with each of the straps  12 ,  14  in contact with a portion of the hook-and-loop fastener  30 ,  32 . Thus, as shown in the perspective view of  FIG. 7 , a single strap  14  can assume a variety of positions, labeled in  FIG. 7  as A, B, and C. 
         [0024]    As those of skill in the art will note, the attachment mechanism described above attaches the upper padded shoulder and chest portion  34  of each strap  12 ,  14  to the frame  10 . In order to function successfully as a strap, the straps  12 ,  14  must also be connected or coupled to the frame  10  at their respective lower edges as well. There are a number of potential ways of doing this. Because the lower portions of the straps  12 ,  14  are load-bearing but not necessarily body-contacting, they generally do not need to be padded along their entire lengths. For that reason, it is generally sufficient to connect the padded upper portion  34  of each strap  12 ,  14  to a piece of webbing to act as a lower portion. The webbing  36  (best seen in  FIG. 1 ) may be, for example, 1 inch webbing. This connection may be by means of a buckle  38  sewn to the bottom of the upper portion  34  of each strap 
         [0025]    If no waist belt  16  is provided, the webbing  36  that serves as the lower portion of the strap  12 ,  14  may simply terminate by attaching to one of a number of small slots  40  that are provided in the frame  10 , or to slots that are specifically provided for that purpose. However, in the illustrated embodiment, the webbing  36  that serves as the lower portion of the straps  12 ,  14  attaches and is sewn into the waist belt  16 . As shown in the exploded view of  FIG. 3 , the waist belt  16  has a large pocket  42 . The frame  10  of the illustrated embodiment terminates in a lower, rounded, generally U-shaped tongue  44 , and the tongue  44  slips into the pocket  42 . The buckle  38  can be used to lengthen or shorten the effective length of the webbing  36  to an appropriate length based on the selected vertical position of the upper portion  34  of the straps  12 ,  14 , and any excess length can be tied off. Generally, the webbing  36  has a length in excess of the minimum required, to provide enough length to go through the buckle  38  and allow for adjustment. 
         [0026]    While the invention has been described with respect to certain embodiments, the embodiments are intended to be exemplary, rather than limiting. Modifications and changes may be made within the scope of the invention, which is defined by the appended claims.