Abstract:
A backpack having a forked frame with curved flat members that are shaped to conform to the curvature of a wearer&#39;s back. The flat members are connected together torsionally by a handle portion that allows each flat member to shift relative to the other to accommodate weight shifts in the backpack load. The forked frame is a single-piece structure that is preferably made of carbon fiber. Although the frame is external relative to the pack, the flat construction of the frame allows it to mate with the pack in a way such that the frame is integrated with the inner sidewall of the pack.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to backpacks, and more particularly, to backpacks having flexible frames.  
       BACKGROUND OF THE INVENTION  
       [0002]     Conventional backpacks typically have a rigid tubular metal frame that is external of the pack or an internal frame. Either way, the frame supports the load within the pack and distributes the load across the wearer&#39;s hips, shoulders, and back. The invention disclosed here is a new frame design that provides a different way of supporting backpack contents and distributing the weight carried by the pack.  
       SUMMARY OF THE INVENTION  
       [0003]     The invention is a backpack having a forked frame made of curved flat members that are shaped to approximately conform to and press against the curvature of a wearer&#39;s back. For the purpose of visualizing what is meant by “curved flat member,” one may liken the shape of these members somewhat to the shape of a steel leaf spring used in the automotive industry. In other words, the curved flat members used in the present invention are dimensionally long and wide, relative to their thickness, and can elastically bend or flex because of their relatively thin thickness. A handle portion of the frame connects the flat members together at the frame&#39;s top. The handle portion, as a connecting piece, enables the flat members to be torsionally flexible relative to each other. This flexibility accommodates weight shifts in the load carried by the backpack. The handle portion also allows the backpack to be carried like a suitcase when it is not being worn.  
         [0004]     The handle portion and the flat members are integrally formed together from a single piece of material—preferably, carbon fiber. The lower portions of the flat members flare outwardly with respect to the portions of the flat members that are connected to the handle portion for providing support in the lumbar region of the back. There is a scapular pad connected to the flat members, near the handle portion, and a pair of lumbar pads connected, one each, to the outwardly flared portions of the flat members for cushioning effect.  
         [0005]     In preferred form, the frame is external of the pack. However, its flat construction also “flatly” integrates the frame with the inside surface of the pack or packsack, i.e., the surface that rides on or against the wearer&#39;s back. While loads in the pack will cause them to flex along their length, and relative to each other, the curvature of the flat members, combined with their relative stiffness, serves to mold the inside surface of the packsack to the curvature of the wearer&#39;s back.  
         [0006]     The backpack has shoulder straps that are conventional in nature, with the exception that each strap has an elastic section that permits the strap to stretch or extend when the backpack is worn. A separate strap or webbing spans the region of each shoulder strap where the elastic section is located. The separate strap is essentially non-elastic and has opposite ends connected to the shoulder strap outside and on opposite sides of the elastic section such that the length of the non-elastic strap is greater than the length of the elastic section when it is in a non-stretched condition (i.e., when the backpack is not being worn). When the backpack is placed on the wearer&#39;s back, the weight in the pack pulls against the straps and stretches the elastic section in each one—the reach of the elastic stretch is limited by the non-elastic strap.  
         [0007]     The handle portion of the frame extends above the pack sack and curves aft relative to the wearer. This feature makes it easy to handle the backpack in certain situations when it isn&#39;t worn because it allows the backpack to be carried like a suitcase or briefcase.  
         [0008]     The features of the invention as described above will become better understood upon review of the following description, which is to be taken in conjunction with the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     In the drawings, like reference numerals and letters refer to like parts throughout the various views, unless indicated otherwise, and wherein:  
         [0010]      FIG. 1  is a pictorial view of a backpack and backpack frame constructed in accordance with a preferred embodiment of the invention;  
         [0011]      FIG. 2  is a pictorial view of the backpack frame;  
         [0012]      FIG. 3  is a top view of the frame shown in  FIG. 2 ;  
         [0013]      FIG. 4  is a front view of the frame shown in  FIG. 2 ;  
         [0014]      FIG. 5  is a bottom view of the frame shown in  FIG. 2 ;  
         [0015]      FIG. 6  is a side view of the frame shown in  FIG. 2 ;  
         [0016]      FIG. 7  is a back view of the frame shown in  FIG. 2 ; and  
         [0017]      FIG. 8  is another pictorial view of the backpack shown in  FIG. 1 , but is taken from an angle looking at the back side of the backpack. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     Referring now to the drawings, and first to  FIG. 1 , shown generally at  10  is a backpack constructed in accordance with the invention summarized above. The backpack has a forked frame, indicated generally at  12 . The frame has two curved flat members  14 ,  16  that are connected together by a handle portion  17 . Referring now to  FIG. 7 , which is a back view of the frame  10  disconnected from the pack or packsack  40 , the lower portions of the flat members  14 ,  16  flare outwardly as indicated at  18 ,  20 , respectively.  
         [0019]     As is best seen in  FIG. 2 , the lower-most region of the outwardly flaring parts or frame regions  18 ,  20  are lumbar-supporting areas or portions, indicated at  22 ,  24 , respectively. Attached to these areas are two lumbar pads  26 ,  28 . Similarly, a scapular pad  30  is connected to the flat members  14 ,  16  near the handle portion  18 . The connection of the pads  26 ,  28 ,  30  to the frame  12  can be done in different ways. In the embodiment illustrated here, the connection is made by the pin and bolt arrangements  32 ,  34  for the lumbar pads and a pin and flange arrangement  36 ,  38  for the scapular pad  30 .  
         [0020]     The frame  12  is connected to the pack or packsack  40  by a series of pins or rivets that are located throughout various openings  42  in the frame  12 . Like most conventional backpacks, the backpack  10  has a pair of shoulder straps  44 ,  46  and waist belt  48 . In this particular instance, however, each shoulder strap  44 ,  46  has an elastic or elasticized section  50 ,  52  that stretches relative to the material that is used to make up other parts of each shoulder strap. Also, attached to each shoulder strap is a separate, substantially non-elastic strap  54 ,  56 .  
         [0021]     These separate nonelastic straps  54 ,  56  have a length that is greater than the length of the elastic sections  50 ,  52  of the shoulder straps when they are not stretched, which is the case when the backpack is not worn, as reflected in  FIGS. 1 and 8 . The opposite ends  58 ,  60  of each non-elastic strap are connected to each shoulder strap outside and on opposite sides of each elastic section.  FIG. 8  is the best illustration of this arrangement. However, when the backpack  10  is placed on a wearer&#39;s back, the weight in the pack  40  puts the shoulder straps  44 ,  46  in tension and stretches the elastic sections  50 ,  52  until they stretch to the point where non-elastic straps  54 ,  56  take up the tension and prevent further stretching.  
         [0022]     The materials used to make the elasticized sections  50 ,  52  and non-elastic straps  54 ,  56  are conventional elastic and nonelastic materials. The backpack frame  12  can be made from different materials, so long as they provide the structural shape described above. However, carbon fiber is the preferred material because of the way it can be molded to make a single integrated frame (as shown at  12  in  FIG. 2 , for example) and because of its attractive appearance. It is believed that a carbon fiber frame of the type described above is unique in the construction of backpacks or backpack frames.  
         [0023]     The handle portion  17  of the frame  12  both connects and allows the flat members  14 ,  16  to torsionally flex relative to each other—which serves to distribute weight as the wearer walks or engages in other physical activities. Except for the torsional flex between members  14 ,  16 , the frame is otherwise relatively rigid, with the understanding that the thin thickness coupled with the flat-sided construction of members  14 ,  16  does allow them to bend elastically forward and backward along with the torsional movement that one might have relative to the other. Dimensionally, in the backpack  10  illustrated here, the length of the curved flat members  14 ,  16  from handle portion  17  to scapular regions  22 ,  24  is approximately 18 inches. The width of the flat members  14 ,  16  near the scapular pad  30  is approximately 2.25 inches. They are about 0.125 inches thick. It is to be understood that these dimensions are examples only and will vary for different kinds of backpacks. The backpack  10  illustrated here is a size that is typically worn by students, although it could be used for day hikes as well. It may be possible to enlarge the dimensions of the frame for use in a backpack of the type used for overnight hiking or expeditions, although that has not been tried in a prototype, as of yet.  
         [0024]     While openings  42  are provided in the frame  18  for using pins or rivets to connect the frame to the packsack  40 , the mode of connection can be done in different ways. The frame can be permanently attached to the pack  40  or removable attachments (not shown) would provide a means for using the same frame for other types of packs or bag arrangements connected to the frame. As described above, the frame&#39;s handle portion  17  extends above the pack  40  so that it is easy to grip as an integrated part of the frame. It is curved aft, as is best seen at  62  in  FIG. 6 , for the purpose of making it easier to grip and/or carry the pack  10  by hand like a suitcase.  
         [0025]     The lumbar and scapular pads  26 ,  28 ,  30  can also be connected to the frame in different ways and they can be adjusted to alter the way weight is distributed and/or to improve comfort. The scapular pad  30  in particular can be adjusted in height because the frame  12  has a plurality of pin openings  64  (see  FIG. 2 ) that allow the pad  30  to be moved upwardly or downwardly relative to the frame. This adjustment is made depending on the height of the wearer.  
         [0026]     While the wearer is not illustrated in the drawings, it is easy to see that the curvature of the frame&#39;s flat members  14 ,  16  allow the frame to follow the shape of the wearer&#39;s back so that the frame causes the pack  40  to conform to and press against the back. In this respect, the frame pulls the inner surface  66  of the pack  40  against the wearer&#39;s back in a comfortable fashion. The thin thickness of the frame  12  allows it to be integrated with the inner surface  66  of the pack. While it is described and illustrated here as an “external” frame, its thin construction integrates it flatly with the pack walls so that the frame  12  and the material making up the inner surface  66  present, together, a fairly uniform surface that presses against the wearer&#39;s back. It may be possible to use the same frame arrangement as an “internal” frame as well, although that embodiment has not yet been created in prototype form.  
         [0027]     The foregoing description is not to be read in a limiting sense. What is considered to be the spirit and scope of the invention is defined in the patent claim or claims that follow, the interpretation of which is to be made in accordance with established doctrines of claim interpretation.