Abstract:
A backpack having a shoulder harness ( 14 ) and a hip harness ( 20 ). The shoulder harness preferably consists of a pair of padded shoulder strap assemblies ( 14   a  and  14   b ) that have elongate pockets ( 27 ) sewn into their outer linings into which contour plates ( 26 ) are fitted to control the lateral curvature of the straps. The plates are selected to have the stiffness and shape to suit the chest and shoulder shape of the individual user. The hip harness ( 20 ) is preferably divided into independent left and right halves ( 20   a  and  20   b ) that are each pivotally attached to a frame element within the front lower portion of the pack. While the hip harness may be unitary, or the two halves may be more or less tightly coupled together, pivotal attachment of the back of the harness to the pack is highly desirable.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from Australian provisional patent application serial number 2003906034, filed Nov. 3, 2003.  
       TECHNICAL FIELD  
       [0002]     This invention relates to backpacks and to backpack shoulder harnesses and hip harnesses.  
         [0003]     As a matter of convention, the terms ‘front’ and ‘back’, ‘left’ and ‘right’ and ‘lumbar portion’ when used with a backpack have reference to a standing person wearing the pack. Thus, the front of a backpack is the face that lies adjacent the back of the person and the back of the backpack is the part that is most remote from the person when the pack is worn. Similarly, the right and left sides of the pack are those which lie to the right and left of the person wearing the pack, and the lumbar portion of the pack is the lower portion opposed to the lumbar spine of the user at about the level of the hip harness of the backpack.  
       BACKGROUND TO THE INVENTION  
       [0004]     The backpacks with which this invention is concerned are intended for carrying loads on or against the backs of people. They mostly have some form of load-bearing or distributing frame element, a shoulder harness for supporting some of the load on the shoulders of the user and a hip harness for supporting the remainder of the load on the gluteal muscles and/or hips of the user. The frame element may be incorporated in or otherwise attached to a load bag, or it may be used to support a load directly without the mediation of a load bag. It can be omitted altogether, as in light day-packs where the hip and shoulder harnesses are simply attached to the front of the load bag. When present, the frame element can take many different forms. In light packs it can simply be a cloth stiffening panel sewn into the lower front face of a load bag. With heavy packs, a skeletal metal or plastic frame can be employed that extends the full height of the pack—from the lumbar region of the wearer to shoulder level—with the hip and shoulder harnesses securely attached to it. Smaller metal or plastic frame elements are often fitted into pockets in the front of the load bag with the harnesses secured through to the frame. Or, in the absence of a load bag, the frame can be an external framework to which a load such as a box or drum can be directly secured and to which the shoulder and hip harnesses are also directly attached.  
         [0005]     Because of the wide variety of human body shapes and sizes and the wide variety of body movements during walking, climbing, skiing etc, it is difficult to design a back pack—especially one intended to carry substantial loads—to suit a wide variety of people, despite providing adjustable shoulder and hip harnesses. Tailor-making a pack, hip harness, shoulder harness and frame elements to suit an individual is generally impractical for cost reasons. There is therefore a need for a backpack that is better adaptable to a variety of body sizes and walking styles, particularly where substantial loads are carried.  
         [0006]     It is my experience that good harness conformance with the shape and walking motions of the wearer is the primary requirement for backpacks, especially when carrying heavy loads. Padding design and fabric choice are secondary considerations.  
       SUMMARY OF THE INVENTION  
       [0007]     From one aspect, this invention involves a backpack in which the hip harness is attached by a pivot joint that permits the harness to rock from side to side with the movement of the user&#39;s hips when walking. The hip harness may include separate left and right side segments that are pivotally attached to the pack so that they can move independently of the other. Preferably, the harness is attached to one or more frame elements incorporated in the backpack and, where independently movable segments are employed it is preferred that they are pivotally attached to a common frame element to rotate about separate axes. The separate axes preferably extend substantially horizontally and parallel in the front-to-back direction, one on either side of the spine in the lumbar area of a user wearing the pack.  
         [0008]     The backpack preferably includes a primary and substantially inextensible frame element in the lumbar region at the level of the hip harness and, where separate hip harness segments of the type indicated above are used, it is preferable that each segment includes a substantially inextensible hip-plate having front and rear portions. The rear portion of each hip-plate is preferably relatively large and pivotally attached to the primary frame element so that it can overlie the respective gluteus maximus muscle of the user. The front portion of each hip-plate is preferably attached to waist strap and buckle means by which the hip-plates can be coupled together about the waist or the user. Each hip segment preferably includes a padded boot or hip pad that is preferably fitted over the respective hip-plate so as to be interposed between the hip-plate and the body of the user. To mitigate chafing, the edges of the hip-plates may be covered with edging material.  
         [0009]     Preferably, the hip-plate of each segment is encased in a tightly fitting cover or pocket of textile fabric having good tensile strength. This helps to reinforce the plate against tearing along stitch-lines, cracking from the periphery and buckling or crumpling under stress. The hip harness buckle means can be attached directly to the hip-plates or to their pockets, allowing the hip harness to be tightened as much as desired without stretch or creep. Resistance to stretch and creep is further enhanced by the pivotal mounting of the hip-plates on the frame element.  
         [0010]     The use of independently pivoting side segments allows each side of the hip harness to automatically assume the contour of the wearer&#39;s hip region and to move more freely and independently as the pelvis of the walker rocks cyclically during walking or tilts during climbing. It also allows the hip harness to be stowed during storage or transport of the backpack by swinging the side segments upwards against the front of the pack. A zip-around cover flap may be attached to the bottom of the pack, or accommodated within a pocket in the bottom of the load bag, so that it can be pulled out over the stowed hip and shoulder harnesses and zipped in place for transport. This is especially valuable when backpacks are entrusted to the baggage handling systems of airports.  
         [0011]     According to an optional feature, where hip-plates of separate hip harness side segments are pivotally attached to the frame element for movement about laterally spaced axes, the rear portions of the hip-plates may be coupled together below the level of their respective pivot axes by a stabilizing strap to limit simultaneous upward movement of the front portions of the hip-plates when the pack is worn. The stabilizing strap may be of adjustable length so that the wearer can adjust the way in which the load is shared by the side segments as the hips move during walking. Of course, some means of undoing the stabilizing strap is necessary to allow the hip side segments to be rotated to their substantially vertical stowage positions.  
         [0012]     One way of effecting the pivotal joint by which a side segment is attached to the primary frame element is to mount a threaded metal nut or socket on or in the frame at the desired location, to press a metal eyelet into the respective hip-plate and to enter a screw through the eyelet into the nut or socket to pivotally secure the hip-plate and segment to the frame element. It is envisaged that the screw or nut may rotate with the hip-plate in an eyelet or bore formed in the frame element. While lose-riveting the stiffening plate to the primary frame element (so as to allow pivotal movement) is also envisaged, it makes replacement of the hip-plate and segment more difficult. It will be appreciated, however, that the means by which each hip-plate is attached to the frame is not of prime importance, so long as a pivotal joint is effected.  
         [0013]     As already indicated, replaceable padded boot-like covers—here called hip pads—may be fitted over the hip-plates. The length and shape of the hip pads can be chosen to suit the size and shape of the user. The pads can be readily fitted and replaced if desired. The lateral contour of the hip pad will be determined in large part by the lateral contour of the associated hip-plate. The use of the hip-plate and/or its aforementioned pocket to take the tension of the hip harness enables the hip pad to be designed solely for padding and comfort having regard to the intended use of the pack. For example, the carrying of heavy, medium or light loads, bush-walking, alpine ascent and descent, travel in city areas, or day walking.  
         [0014]     From another aspect, the invention comprises a backpack having a shoulder harness including left and right shoulder straps that extend over the shoulders of the user and characterized in that a pocket is formed in the top face of each shoulder strap in the shoulder region and a removable flexible contour plate is fitted into each pocket to shape the respective strap in the lateral (generally horizontal direction). Each shoulder strap is formed with inner or lower padding and with an outer or upper lining and the pocket is formed on or in the upper lining. A series of alternative contour plates of different shapes can be fitted into the pocket to force the strap into different lateral configurations, depending upon the slope and contour of the user&#39;s neck and shoulders. The contour plate additionally serves to mitigate bunching or edge-curling of the shoulder strap padding over the shoulder.  
         [0015]     The plates of the hip and shoulder harnesses are preferably cut from sheet plastic material—such a polypropylene—that is at least one millimeter thick and is substantially inextensible under the loads encountered in backpacks. Such plates are easily flexed in directions orthogonal to their planes but strongly resist coplanar flexing forces. As already indicated, the plates may be confined within a closely fitting textile cover that extends over the edges of the plate and/or edge bound with textile material to reduce chafing of an by their edges. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     Having broadly portrayed the nature of the present invention, a particular example will now be described with reference to the accompanying drawings. However, those skilled in the art will appreciate that many variations and modifications can be made to the example without departing from the scope of the invention as defined by the claims appended hereto. In the accompanying drawings:  
         [0017]      FIG. 1 , is a front elevation of the backpack of the chosen example, showing the hip harness and shoulder harness ready for use.  
         [0018]      FIG. 2  is a front elevation of the backpack of  FIG. 1  showing the hip harness segments in their stowed positions and a cover flap ready for deployment thereover.  
         [0019]      FIG. 3  is a front elevation of the backpack of  FIG. 1  showing the cover flap deployed and the backpack ready for transport.  
         [0020]      FIG. 4  is an enlarged front elevation of the lower portion of the backpack of  FIG. 1  showing the hip-plates, portions of their respective pivot joints and the attached buckle means.  
         [0021]      FIG. 5  is a similar view to  FIG. 4 , with the hip-plates and buckle means removed, the outline of the frame elements being shown in broken lines.  
         [0022]      FIG. 6  is a sectional side elevation of the right segment of the hip harness of  FIG. 1  taken on section plane VI-VI of  FIG. 1 .  
         [0023]      FIG. 7  is a rear elevation of the right hip harness segment and buckle means of  FIG. 1 , showing an optional stabilizing strap.  
         [0024]      FIG. 8  is a similar view to  FIG. 7  showing the right hip-plate of the right hip harness segment with the associated hip pad removed, showing the optional stabilizing strap illustrated in  FIG. 7  together with a second stabilizing strap.  
         [0025]      FIG. 9  is an enlarged front elevation of portion of one of the shoulder strap assemblies of  FIG. 10  showing a contour plate fitted within its pocket.  
         [0026]      FIG. 10  is a plan view of the shoulder harness removed from the backpack of  FIG. 1  and laid out flat on a horizontal surface with its front uppermost and with three pairs of contour plates of different shapes that can be fitted within the pockets of the shoulder straps. 
     
    
     DETAILED DESCRIPTION  
       [0027]     With reference to  FIG. 1 , the backpack  10  of the chosen example has a load-bag  12 , a Y-shape shoulder harness  14 , having left and right padded shoulder strap assemblies  14   a  and  14   b  and a common tail  16  that is adjustably secured to the base  18  of the pack by an anchor buckle  19 , and a hip harness  20  comprised of (i) separate left and right side segments  20   a  and  20   b  pivotally attached to pack  10  near base  18  and (ii) waist buckle means  22 . The front faces of segments  20   a  and  20   b  are covered by pads  64   a  and  64   b  (respectively, which will be described below. An optional lumbar flap  23  may be used to cover buckle  19  and shoulder harness tail  16  when the pack is worn. One end of flap  23  is sewn to base  18  so that the opposite end can be raised and attached by mating Velcro™ patches  23   a  and  23   b  to the front of pack  10 .  
         [0028]     Each strap assembly  14   a  and  14   b  of shoulder harness  14  essentially comprises (i) an elongated padded body  24  arranged to extend over the upper back and respective shoulder and down the respective side of the chest of the wearer, (ii) a load-bearing top-webbing  25  passing downward over the top front face of padded body  24 , and (iii) a contour plate  26  fitted upwardly into a pocket  27  in the upper portion of body  24  that extends over the shoulder of the user. Each top-webbing  25  extends from a respective top anchor buckle  28  that is fixed to the load bag  12  a little below shoulder height. The lower end of each top-webbing  25  terminates at a respective bottom buckle  29  through which an adjustable bottom-webbing strap  30  is passed, one end of bottom-webbing  30  being anchored to base  18  of pack  10  and the other end hanging free to permit easy adjustment by pulling. Except for the use of contour plates  26  and their respective pockets  27  the general configuration and construction of the shoulder harness  14  is well known in the art.  
         [0029]      FIG. 2  shows the pack with the side segments  20   a  and  20   b  of hip harness  20  swung up about their pivots (to be described below) to substantially vertical positions and lumbar flap  23  folded up and attached to the front of the pack in its normal position. A zip-around cover  32 , which is attached to pack base  18  and is normally stowed in a zip-pocket  34  (see  FIGS. 4 and 5 ) formed in the bottom  36  of load bag  12 , is shown unpacked and extended from that pocket in  FIG. 2 .  FIG. 3  shows cover  32  after it has been zipped in place, covering the entire harness system to ready pack  10  for transport.  
         [0030]      FIG. 4  is an enlarged view of the lower portion of the front of pack  10  including the lumbar region, generally indicated by the bracket L.  FIG. 4  shows the lower ends of padded bodies  24  of left and right shoulder strap assemblies  14   a  and  14   b , the lower ends of top-webbings  25 , bottom buckles  29  and bottom webbings  30 . The tail  16  of the shoulder harness  14  and the anchor buckle  19  at the base  18  of pack  10  are also shown, along with zip pocket  34  for cover  32  in the bottom  36  of load bag  12 , but the lumbar flap  23  is omitted for clarity. In  FIG. 4 , the left and right pads  64   a  and  64   b  of hip harness segments  20   a  and  20   b  shown in  FIGS. 1 and 2  have been removed to show left and right flexible plastic hip-plate assemblies  37   a  and  37   b  that form part of the respective segments and will be described with reference to  FIGS. 6, 7  and  8  below. Each hip-plate assembly comprises a sheet-plastic hip-plate  40  sewn into a tightly fitting strong fabric pocket  38  with edge bindings  39 , plates  40  being shown in cut-away areas  41  of the fabric pockets  38 . Hip-plate assemblies  37   a  and  37   b  have relatively narrow front ends  42 , which are shown are shown flexed forwards and inwards and joined by waist buckle means  22  that comprises left and right belt-like webbing straps  44   a  and  44   b  joined by a central buckle  46 . The rear ends of straps  44   a  and  44   b  are sewn directly to front ends  42  of respective hip-plate assemblies  37   a  and  37   b . The relatively large rear or inner end portion  48  of each hip-plate assembly is lobe-like and located to oppose the respective gluteus maximus muscles of the wearer when pack  10  is in place. An eyelet  50  is swaged through each plate assembly  37   a  and  37   b  at approximately the center of the lobe of inner portion  48  so that the plate assembly can be pivotally secured to the frame of pack  10  by a countersunk-head screw  52  passing though eyelet  50 , as will be described more particularly with reference to  FIGS. 5 and 6 . It is to be noted that the axes of screws  52  are substantially horizontal and parallel and extend generally in the front-to-back direction (when the pack is worn).  
         [0031]      FIG. 5  is a similar view to that of  FIG. 4  but with shoulder harness  14  and hip harness  20  removed, the latter being simply effected by first removing screws  52  ( FIG. 4 ) leaving internally threaded nuts  54  in place. The exteriors of nuts  54  are cylindrical and extend through respective eyelets  55  that are swaged into the cloth facing  56  of the load bag  12  of pack  10 . The lower ends of bottom webbings  30  of the shoulder harness  14  are anchored to the base of load bag  12  by being sewn between respective sides of facing  56  and the front of load bag  12 .  
         [0032]     In this example, the primary frame element is a lightweight, strong flat piece of plastic or aluminium, shown in outline by broken lines at  60  in  FIG. 5  because it lies behind facing  56 . In this example, primary frame element  60  is supplemented by left and right crossed strap-like secondary frame elements  61   a  and  61   b  respectively, which are preferably formed from aluminum sheet though plastic sheeting may also be used. Each secondary element extends diagonally upward to provide at their top ends (not shown) anchor points for (respectively) the right and left anchor buckles  28  ( FIG. 1 ) of shoulder harness  14 . Secondary frame elements  61   a  and  61   b  are also shown in broken lines as they also lie behind the facing  56  of load bag  12 .  
         [0033]      FIG. 6  is a sectional side elevation of right segment  20   b  and portion of the front of load bag  12  taken on section plane VI-VI shown in  FIG. 1 , which passes through the right pivot joint formed (in part) by the right hand one of screws  52 . It is to be noted that the sectional dimensions of the components shown in  FIG. 6  have been exaggerated for the sake of clarity. Primary frame element  60  is located between cloth facing  56  (see  FIG. 5 ) and a cloth backing  58  that form the font of load bag  12  and is held in position by the swaging of eyelet  55  through facing  56 , frame element  60  and backing  58 . In the example shown, nut  54  is swaged into the bottom end of the right secondary frame element  61   b  and is of tubular form so that it extends forwards through the right eyelet  55  so as to positively locate the bottom end of secondary frame element  61   b  with respect to primary frame element  60 . Both secondary frame elements  61   a  and  61   b  are located within load bag  12  immediately behind backing cloth  58 .  
         [0034]     It might be noted that  FIG. 6  also illustrates—in section—portion of the base  18  of pack  10  including zipped pocket  34  in the bottom  36  of and showing cover  32  packed into pocket  34 .  
         [0035]     Referring now to  FIGS. 7 and 8  as well as to  FIG. 6 , right hip harness segment  20   b  basically consists of right hip-plate assembly  37   b , (which includes plastic hip-plate  40  with sewn-on fabric cover  38  and edging  39 , and with eyelet  50  swaged therethrough) and padded right boot  64   b  fitted over the front of hip-plate assembly  37   b . Boot  64   b  comprises a foam core  66  encased in a sewn fabric cover  68  having a rear pocket  70  accommodating lobe  48  of hip-plate  37   b  and having a rear strap-like bridge  72  ( FIG. 7 ) accommodating the narrow front portion  42  of hip-plate  37   b  (along with the inner end of right strap  44   b  of buckle means  22 ).  
         [0036]     By way of review, it is to be noted that screws  52 , nuts  54  and eyelets  50  and  55  serve to positively locate and assemble primary frame element  60 , secondary frame elements  61 , and left and right hip segments  20   a  and  20   b  together as a functioning assemblage. Primary frame element  60  thus serves to pivotally anchor the side segments  20   a  and  20   b  of hip harness  20 , setting the relative location and spacing of left and right segments  20   a  and  20   b  and allowing buckle means  22  to be tightened without displacing the segments of the hip harness  20 . A thread-locking compound can be used to prevent screws  52  working loose in nuts  54  during use.  
         [0037]     It will be appreciated that there are many alternative arrangements by which the desired function of the side segments of the hip harness can be effected. A threaded nut can be carried by the primary frame element and a screw or bolt entered forwards from within the load bag of the pack. A tubular rivet that passes through all the components of the joint could be employed. Such a rivet could lock or clamp the primary and secondary frame elements together while allowing free-rotation of the hip-plate assemblies and their associated side segments. The secondary frame elements (if present, for they are optional) need not be fixed by the screw, rivet or the like that forms the pivot joint, but can be attached to the primary frame element elsewhere. Or the primary and secondary frame elements may form an integral cut or molded plastic structure that is entirely housed within the front face of the load bag.  
         [0038]      FIGS. 4, 7  and  8  show an optional stabilizer link  80  that ties the lobe portions  48  of hip-plates assemblies  37   a  and  37   b  together so as to restrict their relative angular movement. Users with broad hips may find this helpful when carrying heavy loads so as to reduce the amount of load-shifting from one hip to the other while still permitting some pivotal movement of the hip harness. As shown in  FIG. 4 , link  80  comprises left and right straps  82   a  and  82   b  joined by a buckle  84  in such a way that the effective length of the link can be accurately adjusted, strap  82   a  being sewn to the lobe of left hip-plate  37   a  at a point below the pivot axis defined by the axis of screw  52  or eyelet  50  and strap  82   b  being sewn to the lobe of right hip-plate  37   b  in a corresponding location.  
         [0039]     As an alternative or an addition to link  80 , the narrow front portions  42  of hip-plates can be fitted with longer side stabilizer straps that attach to buckles at the base  18  of load bag  12  and on the same side. An example for the right side of the pack is shown a right side stabilizer strap  84   b  on right hip-plate  37   b  in  FIG. 8 . The free end of right side stabilizer strap  84   b  attaches to right side buckle  85   b  shown in  FIG. 5 . The left side stabilizer strap (not shown) attaches to left side buckle  85   a  shown in  FIG. 5 . When heavy loads are carried the side stabilizer straps resist the tendency of buckle means  22  to rise; that is, they transfer some of the weight from the shoulders and buttocks to the hips.  
         [0040]     The use of contour plates  26  and pockets  27  in the shoulder strap assemblies  14   a  and  14   b  will now be described with reference to  FIGS. 9 and 10 .  FIG. 9  is an enlarged front perspective view of the portion of the left shoulder strap assembly  14   a  that normally rests on the shoulder of the user. A guide to the orientation of this portion of shoulder strap assembly is provided by the broken line on the left of  FIG. 9  indicating the front face of load bag  12 .  FIG. 10  is a plan view of shoulder harness  14  depicted as if lying on a horizontal surface and viewed from the back and top so that left and right shoulder strap assemblies  14   a  and  14   b  appear reversed with respect to  FIG. 1 . Most of the tension webbings  25  (see  FIG. 1 ) have been cut away for clarity in  FIGS. 9 and 10 .  
         [0041]     As already noted, left and right shoulder strap assemblies  14   a  and  14   b  have padded bodies  24 . The padding is normally heaviest in the shoulder region where it rests against the tops of the shoulders and, sometimes, the pectoral muscles of the user, this heavy padding being indicated at  90  in the perspective view of the left strap assembly  14   a  in  FIG. 9  and in the front elevation of  FIG. 1 . As described with respect to  FIG. 1 , a pocket  27  is formed in the outer or upper lining of the shoulder portion of each strap assembly to take a selected contour plate  26 , most of which is shown in broken lines in  FIG. 9  because it is located within pocket  27 . The purpose of contour plate  26  is to laterally shape the shoulder portions of the strap assemblies so as to make them more comfortable under load and so as to inhibit the bunching or curling of padded portion  90 .  
         [0042]     Because of the wide variation in shoulder, chest and breast size and shape between people and, in particular, between men and women, the optimum lateral curve of the shoulder portions of the strap assemblies will vary widely even for the same pack and load. It has been found that much of this variation can be accommodated by selecting between contour plates of different, shapes, stiffness and curvature for use in a common shoulder harness that has tight-fitting pockets shaped to take the plates. An added degree of accommodation is possible by varying the location of the pockets along the shoulder strap assemblies of the shoulder harness. This may be done by forming multiple pockets in the outer lining or by controlling the vertical location of a contour plate within a long pocket. In general, however, only one pocket over each shoulder will be sufficient as in the illustrative example.  
         [0043]      FIG. 10  shows shoulder harness  14  of the pack of  FIG. 1  laid out in the manner indicated above, with tension webbings  25  cut away and pockets  27  showing. Three alternative contour plates  26   d ,  26   e  and  26   f  having increasing curvature are shown along side each pocket  27 . Conveniently, the plates may be stamped or cut from plastic sheeting between 0.5 and 3 mm in thickness with the thicker plates having holes formed therein to reduce weight if desired. Plates  26   d  are shown with holes  92  for this purpose. As in  FIG. 10 , the alternative plates may be relatively short and may all be of essentially the same width (though of differing curvature). As indicated in  FIG. 9 , they may be relatively long and of tapering form. If desired, the plates may be enclosed in a fabric pocket with the perimeter finished with a binding tape in a similar way to the reinforcing plates  40  of hip-plate assemblies  37   a  and  37   b.    
         [0044]     It is desirable that pockets  27  are formed with upper and lower layers of material securely sewn together on their sides and lower ends, each pocket then being secured to the padded portion of the corresponding strap assembly  14   a  or  14   b . Thus, selected contour plate does not come into contact with the padding  90  of the strap and can be made a firm fit within pocket  27 . The material of the upper and lower surfaces of the pocket  27 , as well as adjacent material covering padded body  24 , is preferably of woven construction and cut on the bias so as to facilitate conformity of this region the strap assembly to the shape of curved plates such as  26   f . The bias cut is indicated by hatching  96  in  FIG. 9 .  
         [0045]     It will be appreciated by those skilled in the art that the backpack of the chosen example offers many advantages over known backpacks in the comfortable distribution of the load between the shoulders and the hips, this being achieved in important part by the use of the contour plates in the shoulder harness and the reinforcing plates of the hip harness. Important and separate advantages are also obtained from the use of independently pivoted hip harness segments. However, those skilled in the art will also appreciate that many variations and additions can be made to the backpack of the example without departing from the scope of the invention as defined by the following claims.