Abstract:
A retractable shoulder strap for portable objects, such as bags, purses, briefcases or carry-on luggage, comprises a shoulder pad, an elongated strip of pliant material, a plurality of holes positioned at substantially uniform intervals along the length of the elongated strip, and retractors located inside the shoulder pad. Extendible guide wires passing through the plurality of holes connect the ends of the elongated strip to the retractors, which are spring-biased to automatically retract the guide wires and stow the elongated strip inside internal storage spaces in the shoulder pad, thereby eliminating slack in the strap when no tension is applied to the ends of the elongated strip. When tension is applied to the ends of the elongated strip, the portions of the elongated strip stowed in the internal storage spaces of the shoulder pad are automatically extracted, thereby increasing the length of the strap to facilitate normal over-the-shoulder use.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     FIELD OF ART 
     The present invention relates generally to shoulder straps for portable carrying devices, such as purses, handbags, briefcases, satchels, suitcases, duffle bags, carry-on luggage, computer bags, athletic bags and equipment cases. More particularly, the invention relates to shoulder straps that automatically increase or decrease their overall lengths in accordance with the amount of weight or tension supported by or applied to the distal ends of the shoulder strap. 
     BACKGROUND 
     Personal carrying devices, such purses, handbags, briefcases, satchels, suitcases, duffle bags, carry-on luggage, computer bags, athletic bags and equipment cases (hereafter referred to collectively as “bags”), often include a shoulder strap to facilitate carrying the bag by hanging the strap over the user&#39;s shoulder so that the bag hangs in the general vicinity of the user&#39;s hand. Generally speaking, shoulder straps for bags typically comprise a flexible strip of pliant material, such as nylon or leather, which is attached to opposite ends or the sides of the bag. 
     Unfortunately, when the user removes the shoulder strap from his or her shoulder, and carries the bag in his or her hand, the shoulder strap tends to fall downward and dangle beneath the bag while the bag is being carried, thereby exposing the user and others to danger and potential injuries resulting from tripping over the dangling strap, or accidentally allowing the dangling strap to get caught or snagged on a stationary object (or, even worse, a moving object) in the user&#39;s immediate vicinity. If the bag is placed on the ground, the floor or any other surface, the shoulder strap usually falls to the ground, the floor or other surface, where it will likely expose the user and others to danger and potential injuries resulting from tripping over the strap. Also, the strap will be exposed to increased levels of dirt, dust, soil, debris and liquid that, over time, causes the shoulder strap to take on a soiled, damaged, unattractive and unprofessional appearance. Also, when the bag is placed on top of rolling luggage, the dangling strap often falls down over the edge of the rolling luggage while the bag and luggage are moving, thereby creating another potentially serious risk of snagging, tripping and personal injury. 
     In addition, a loose or dangling shoulder strap that hangs beneath the bag when the bag is carried or lifted by its body or handle can be a substantial inconvenience because (1) the dangling shoulder strap tends to get caught between the bag and the ground when the bag is put down, thereby making the standing position of the bag less stable, (2) the dangling strap hangs down from overhead storage bins in airplanes and trains, causing safety concerns, (3) the dangling strap frequently must be removed to pass through airport security and scanning equipment, (4) it is much harder to use one hand to pick up the bag and move the shoulder strap onto the shoulder when the shoulder strap is wedged between the bag and ground, and (5) the dangling shoulder strap tends to lie in the aisles of airplanes and trains when the bag is stored underneath or beside a seat, creating a tripping hazard. 
     Although a variety of different devices and mechanisms have been introduced for adjusting, retracting and securing loose and dangling shoulder straps for bags, the conventional devices and mechanisms are often unreliable, or otherwise too complicated, expensive or unattractive for a majority of users. Moreover, most of the conventional devices and mechanisms for adjusting, retracting and securing loose and dangling shoulder straps add too much cost and too much time to the manufacturing process, as well as a substantial amount of weight to the combined weight of the bag and the shoulder strap. 
     Accordingly, there is considerable need in the handbag, carry-on, briefcase, athletic bag and luggage industries for a convenient, reliable and inexpensive shoulder strap for bags, wherein the shoulder strap is configured to automatically retract when tension is removed from the strap. There is a further need for an automatically retracting shoulder strap that is both compact and lightweight, and that will not hang below the bottom of the bag or drag on the ground when the shoulder strap is not in use. There is also a need for a retractable shoulder strap that maintains a clean, attractive and professional appearance when the shoulder strap is not being used to carry the bag to which it is attached. And finally, there is also a pressing need for a personal carrying device having a shoulder strap characterized by all of these desirable features. 
     SUMMARY OF THE INVENTION 
     As will be described in more detail below, aspects and embodiments of the present invention address the above-described needs, as well as other deficiencies and problems associated with known shoulder straps, by providing a retractable shoulder strap for a portable object, such as a purse, handbag, briefcase, satchel, suitcase, duffle bag, carry-on luggage piece, computer bag, athletic bag or equipment case. In general, the retractable shoulder strap of the present invention comprises a shoulder pad, an elongated strip of pliant material, a plurality of holes positioned at intervals along the length of the elongated strip of pliant material, and a pair of retractors located inside the shoulder pad, the pair of retractors having a pair of retractable spindles configured to wind and unwind a pair of extendible guide wires connected to the distal ends of the shoulder strap and passing through the plurality of holes in the elongated strip of pliant material. 
     More specifically, the shoulder pad comprises a base wall and a cover, which are joined together to define (1) a pair of openings at opposite ends of the shoulder pad, (2) a pair of internal storage spaces adjacent to the pair of openings, and (3) a retractor housing area bounded by the base wall, the cover and the pair of internal storage spaces. The elongated strip of pliant material, which passes through the pair of openings in the shoulder pad, comprises a forward section, a middle section and a rearward section. The middle section is fixedly attached to the base wall. A portion of the forward section extends through one of the openings in the pair of openings so that the distal end of the forward section is located on the outside of one of the internal storage spaces in the shoulder pad. A portion of the rearward section extends through the other opening in the pair of openings so that the distal end of the rearward section is located on the outside of the other internal storage space. Preferably, a pair of fasteners are attached to the distal ends of the forward and rearward sections of the elongated strip of pliant material, the pair of fasteners comprising, for example, hooks, clasps or buckles, configured to permit the user to releasably fasten the forward and rearward sections of the elongated strip to the portable object (i.e., to the top, sides or ends of the purse, handbag, briefcase, satchel, suitcase, duffle bag, carry-on luggage piece, computer bag, athletic bag or equipment case). 
     The pair of retractors are located inside the retractor housing area of the shoulder pad. Ideally, the pair of retractors are fixedly connected to the retractor housing area. Each retractor in the pair of retractors has a rotatable spindle and an extendible guide wire configured to wind around the rotatable spindle. The distal ends of each one of the extendible guide wires is attached to the distal ends of the forward and rearward sections, respectively, of the elongated strip of pliant material so that the pair of extendible guide wires pass through the plurality of holes in the forward and rearward sections of the elongated strip of pliant material. 
     Notably, the pair of rotatable spindles in the pair of retractors are biased so that, when no tension is applied to the distal ends of the forward and rearward sections of the elongated strip of pliant material, the pair of rotatable spindles will automatically rotate in a direction that winds the pair of extendible guide wires around the pair of rotatable spindles, thereby causing the forward and rearward sections of the elongated strip of pliant material to be retracted into and stored inside the pair of internal storage spaces of the shoulder pad. The rotatable spindles may be biased toward rotating in the direction of winding up the pair of extendible guide wires by any suitable biasing mechanism, including without limitation a coiled spring. 
     When a sufficient amount of tension is applied to the distal ends of the forward and rearward sections of the elongated strip of pliant material to overcome the bias on the pair of rotatable spindles, the pair of rotatable spindles will rotate in the opposite direction to unwind the pair of extendible guide wires from the pair of rotatable spindles. The combination of the tension applied to the distal ends of the forward and rearward sections of the elongated strip and the unwinding and releasing of the pair extendible guide wires permits the forward and rearward sections of the elongated strip of pliant material stored inside the pair of internal storage spaces of the shoulder pad to be pulled out of the pair internal storage spaces through the pair of openings in the shoulder pad. When the forward and rearward sections of the elongated strip are extended in this manner, the user can easily place the shoulder pad on his or her shoulder and use the shoulder strap in the conventional manner. 
     Ideally, the portions of the forward and rearward sections of the elongated strip of pliant material that lie outside the pair of openings in the shoulder pad when the shoulder strap is extended are configured to automatically bend and repeatedly fold back upon themselves, in accordion fashion, when the distal ends of the forward and rearward sections are pulled toward the shoulder pad by the pair of extendible guide wires. As a result of the continued pulling by the pair of extendible guide wires, these folded portions of the forward and rearward sections are retracted and stored inside the pair of internal storage spaces in the shoulder pad, thereby hiding the folded portions of the forward and rearward sections of the elongated strip from view while the shoulder strap is in the retracted position. Conversely, when a sufficient amount of tension is applied to the distal ends of the forward and rearward sections of the elongated strip to overcome the bias on the pair of rotatable spindles, the folded portions of the forward and rearward sections of the elongated strip of pliant material that was previously stored inside the pair of internal storage spaces, respectively, automatically unfold as the forward and rearward sections of the elongated strip are being pulled through the pair of openings and extracted from the internal storage spaces. 
     In another aspect of the present invention, there is provided a personal carrying device, comprising a receptacle (such as a purse, briefcase, a carry-on or a computer case), a shoulder pad, an elongated strip of pliant material, a pair of retractors, and a pair of fasteners for releasably attaching the elongated strip to the receptacle. The shoulder pad comprises a base wall and a cover joined together to define (1) a pair of openings at opposite ends of the shoulder pad, (2) a pair of internal storage spaces adjacent to the pair of openings, and (3) a retractor housing area bounded by the base wall, the cover and the pair of internal storage spaces. The elongated strip of pliant material has a forward section, a middle section and a rearward section. The middle section is fixedly attached to the base wall. A portion of the forward section is stored inside one of the internal storage spaces. And a portion of the rearward section is stored inside the other internal storage space. 
     The pair of retractors are located inside the retractor housing area of the shoulder pad. Each retractor has an extendible guide wire and a rotatable spindle that is biased to automatically wind the extendible guide wire around the rotatable spindle. The distal ends of the extendible guide wires are attached, respectively, to the distal ends of the forward and rearward sections of the elongated strip of pliant material. When the shoulder pad, the forward section and the rearward section of the elongated strip are allowed to support the weight of the receptacle, the weight of the receptacle produces a sufficient amount of tension at the distal ends of the forward section and the rearward section of the elongated strip of pliant material to overcome the bias on the pair of rotatable spindles. This causes the pair of rotatable spindles to rotate in a direction that unwinds the pair of extendible guide wires from around the pair of rotatable spindles. The unwinding of the extendible guide wires and the tension produced by the weight of the receptacle combine to pull the portions of the forward section and the rearward section of the elongated strip stored in the pair of internal storage spaces through the openings of the shoulder pad, thereby extracting the forward and rearward sections of the elongated strip from the internal storage spaces. 
     Conversely, when the tension (and/or the weight of the receptacle) is removed from the components of the shoulder strap, the biasing force in the retractors will cause the pair of rotatable spindles to rotate in the opposite direction to wind the pair of extendible guide wires around the pair of rotatable spindles, respectively, thereby retracting the pair of extendible guide wires into the pair of retractors. When this happens, the pair of extendible guide wires will pull the forward and rearward sections of the elongated strip of pliant material back into the pair of internal storage spaces in the shoulder pad. Consequently, substantially all of the slack is removed from the shoulder strap, thereby preventing the shoulder strap from hanging loosely below the bottom of the receptacle, where it could potentially expose the user or others to unnecessary risks of snagging, entanglement and/or tripping. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention and various aspects, features and advantages thereof are explained in more detail below with reference to exemplary and therefore non-limiting embodiments and with the aid of the drawings, which constitute a part of this specification and include depictions of the exemplary embodiments. In these drawings: 
         FIG. 1  shows a retractable shoulder strap, constructed in accordance with an exemplary embodiment of the present invention, in which the forward and rearward sections of the strap are mostly extended. 
         FIG. 2  shows the retractable shoulder strap of  FIG. 1  with the forward and rearward sections of the shoulder strap fully retracted and concealed within the pair of openings located at opposite ends of the shoulder pad, thereby causing the base wall of the shoulder pad in the shoulder strap to abut the top of the briefcase to which the shoulder strap is releasably attached. 
         FIG. 3  shows a retractable shoulder strap, constructed according to an exemplary embodiment of the present invention, in a fully-retracted state, without any bag, purse or briefcase attached. 
         FIG. 4  shows a close-up view of one end of the shoulder pad according to one embodiment of the present invention. 
         FIGS. 5 and 6  show, respectively, the forward section and the rearward section of the elongated strip of pliant material according to an embodiment of the present invention. 
         FIG. 7  shows another view of a shoulder strap constructed in accordance with an embodiment of the present invention, in which the cover has been cut away in order to better illustrate the internal features of the shoulder pad. 
         FIG. 8  shows a sectioned view of an exemplary retractor suitable for use with some embodiments of the present invention. 
         FIGS. 9 and 10  show, respectively, how a user would typically use a shoulder strap constructed in accordance with one embodiment of the present invention. 
         FIGS. 11 and 12  show, respectively, a top perspective view and a bottom perspective view of an embodiment of a retractable shoulder strap constructed according to an alternative exemplary embodiment of the present invention, wherein the cover and the base wall of the shoulder pad are constructed from a flexible polymer material, the cover and the base wall comprising ridges and ribs to support flexibility. 
         FIGS. 13 and 14  show, respectively, the embodiment of the retractable shoulder strap of  FIGS. 11 and 12 , with the cover of the shoulder pad removed to better illustrate the arrangement of the internal components of the shoulder pad. 
         FIG. 15  shows the embodiment of the retractable should strap depicted in  FIGS. 11 through 14 , in a flexed position over the user&#39;s shoulder. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     It is anticipated that embodiments of the present invention may be utilized in a variety of different industries, including without limitation, the fashion, business, sports, military and travel industries, or any other industry involving portable carriers and personal carrying devices. 
       FIG. 1  shows a retractable shoulder strap  100 , constructed in accordance with an exemplary embodiment of the present invention, attached to a portable briefcase  102 . As shown in  FIG. 1 , the shoulder strap  100  generally comprises a shoulder pad  105  having a base wall  110  and a cover  115 . The shoulder strap  100  also comprises an elongated strip  145  of pliant material (e.g., nylon or leather) that passes through the interior sections of the shoulder pad  105  via a pair of openings  125   a  and  125   b  located at opposite ends of the shoulder pad  105 . The interior sections of the shoulder pad  105  are not visible in  FIG. 1  because they are concealed by the cover  115  and the base wall  110  of the shoulder pad  105 . However, the interior sections of the shoulder pad  105  are shown in the cut-away view depicted in  FIG. 7 , which is discussed in more detail below. 
     The elongated strip  145  of pliant material comprises a forward section  150 , a middle section (not shown in  FIG. 1 ) and a rearward section  160 . As illustrated by  FIG. 1 , the proximal end  151  of the forward section  150  of the elongated strip  145  passes into the opening  125   a  of the shoulder pad  105 . However, a substantial portion of the forward section  150  remains on the outside of the opening  125   a  of the shoulder pad  105 . Likewise, the proximal end  161  of the rearward section  160  of the elongated strip  145  passes into the opening  125   b  of the shoulder pad  105 , leaving a substantial portion of the rearward section  160  on the outside of the opening  125   b  of the shoulder pad  105 . 
     As further shown in  FIG. 1 , a pair of fasteners  197   a  and  197   b  are connected, respectively, to the distal ends  153  and  163  of the forward section  150  and rearward section  160  of the elongated strip  145 . These fasteners  197   a  and  197   b  are used to releasably attach the portable briefcase  102  to the distal ends  153  and  163  of the forward section  150  and rearward section  160 . In addition, a pair of extendible guide wires  180   a  and  180   b  are also connected to the distal ends  153  and  163 , respectively, of the forward section  150  and rearward section  160  of the elongated strip  145 . The extendible guide wires  180   a  and  180   b  pass through a plurality of holes (best shown in  FIGS. 5 and 6 ) located at substantially uniform intervals along the lengths of the forward section  150  and rearward section  160  of the elongated strip  145 . Although not shown in  FIG. 1 , the other ends of the extendible guide wires  180   a  and  180   b  are connected to a pair of rotatable spindles located inside a pair of retractors, respectively, which are in turn located in an interior section of the shoulder pad  105 . 
     The pair of rotatable spindles inside the pair of retractors are biased to rotate in a direction that causes the extendible guide wires  180   a  and  180   b  to be pulled into the shoulder pad  105  through the pair of openings  125   a  and  125   b.  Therefore, as the distance between the shoulder pad  105  and the portable briefcase  102  decreases, the biasing effect on the rotatable spindles cause the extendible guide wires  180   a  and  180   b  to wind around the rotatable spindles and withdraw into the shoulder pad  105  via the openings  125   a  and  125   b.  The withdrawal of the extendible guide wires  180   a  and  180   b  into the shoulder pad  105  automatically pulls the forward section  150  and the rearward section  160  through the pair of openings  125   a  and  125   b  and into the internal storage spaces  135   a  and  135   b  of the shoulder pad  105 . 
       FIG. 2  shows the retractable shoulder strap  100  of  FIG. 1  with the forward section  150  and rearward section  160  of the elongated strip  145  in their fully retracted positions. As shown in  FIG. 2 , the forward section  150  and the rearward section  160  are both substantially concealed inside the shoulder pad  105 , and only the fasteners  197   a  and  197   b  remain visible on the outside of the pair of openings  125   a  and  125   b  of the shoulder pad  105 . When the forward section  150  and the rearward section  160  are in their fully retracted positions inside the shoulder pad  105 , the base wall  110  of the shoulder pad  105  remains neatly and conveniently affixed to the top of the portable briefcase  102  instead of dangling loosely toward the floor or the ground.  FIG. 3  shows a retractable shoulder strap  100 , constructed according to an exemplary embodiment of the present invention, in a fully-retracted state, without a bag, purse or briefcase attached. 
       FIG. 4  shows a close-up view of the fastener  197   b  and the opening  125   b  located at one end of the shoulder pad  105  according to one embodiment of the present invention. Although the fastener  197   b  in  FIG. 4  is a clasp, it will be appreciated by those skilled in the art that a variety of other types of fasteners might be used without departing from the scope of present invention, including without limitation, a hook, a buckle or a snap. 
       FIGS. 5 and 6  show, respectively, the forward section  150  and the rearward section  160  of the elongated strip  145  of pliant material according to the preferred embodiment of the present invention. As shown in  FIG. 5 , the forward section  150  of the elongated strip  145  includes multiple pairs of holes  165   a - 165   c  located at substantially uniform intervals along the center of the forward section  150 . In this case, the multiple pairs of holes  165   a - 165   c  are located at substantially uniform intervals along the forward section  150 . The holes in each pair of holes are separated by one of the folds in the plurality of folds  195   a  in the forward section  150 . The extendible guide wire  180   a  that passes out of the opening  125   a  in the shoulder pad  105  also passes through each hole in the multiple pairs of holes  165   a - 165   c  in the forward section  150 . The substantially uniform spacing of the multiple pairs of holes  165   a - 165   c  ensures that when the extendible guide wire  180   a  is retracted into the shoulder pad  105 , the forward section  150  of the elongated strip  145  will be forced to repeatedly bend and fold back upon itself to form the plurality of folds  195   a  that will be pulled through the opening  125   a  and stored in the internal storage space  135   a  of the shoulder pad  100 . In some embodiments, the multiple pairs of holes  165   a - 165   c  may be reinforced by grommets (not shown in the figures). 
     As shown in  FIG. 6 , the rearward section  160  of the elongated strip  145  includes multiple pairs of holes  165   d - 165   f  located at substantially uniform intervals along the center of the rearward section  160 . The multiple pairs of holes  165   d - 165   f  are located at substantially uniform intervals along the rearward section  160 . The holes in each pair of holes are separated by one of the folds in the plurality of folds  195   b  in the rearward section  160 . The extendible guide wire  180   b  that passes out of the opening  125   b  in the shoulder pad  105  passes through the multiple pairs of holes  165   d - 165   f.  The substantially uniform spacing of the multiple pairs of holes  165   d - 165   f  ensures that when the extendible guide wire  180   b  is retracted into the shoulder pad  105 , the rearward section  160  of the elongated strip  145  will also be forced to repeatedly bend and fold back upon itself to form the plurality of folds  195   b,  which will be pulled through the opening  125   b  and stored in the other internal storage space  135   b  of the shoulder pad  100 . 
       FIG. 7  shows another view of a shoulder strap  100  constructed in accordance with an embodiment of the present invention. In  FIG. 7 , however, the cover  115  has been cut away in order to better illustrate the internal features of the shoulder pad  105  of the shoulder strap  100 . As shown in  FIG. 7 , the internal features of shoulder pad  105  include a pair of internal storage spaces  135   a  and  135   b  located just inside of the pair of openings  125   a  and  125   b,  respectively. Interposed between the internal storage spaces  135   a  and  135   b  is a retractor housing area  140  to accommodate a pair of retractors  170   a  and  170   b.  The retractors  170   a  and  170   b  may be fixedly secured by any suitable means (including without limitation, tape, thread or glue) to the base wall  110  of the shoulder pad  105 , and/or the middle section  155  of the elongated strip  145  of pliant material, and/or the cover  115 . The retractors  170   a  and  170   b  typically face in opposite directions so that the extendible guide wires  180   a  and  180   b  (not visible in  FIG. 7 ) feed out from the retractors  170   a  and  170   b  in opposite directions toward the pair of openings  125   a  and  125   b  of the shoulder pad  105 . 
     The elongated strip  145  of pliant material passes through the pair of openings  125   a  and  125   b  at opposite ends of the shoulder pad  105 . Ideally, the elongated strip  145  passes underneath the retractors  170   a  and  179   b,  so that the middle section  155  of the elongated strip  145  is sandwiched between and fixedly secured to the base wall  110 . In alternative embodiments, however, these components may instead be arranged so that the middle section  155  of the elongated strip  145  passes between the cover  115  and the top of the retractors  170   a  and  170   b.  In this configuration, the middle section  155  of the elongated strip  145  may be fixedly secured (by tape, thread or glue, for example) to the cover  115 , the top of the retractors  170   a  and  170   b,  or both the cover  115  and the top of the retractors  170   a  and  170   b.    
     The forward section  150  and the rearward section  160  of the elongated strip  145  are shown in  FIG. 7  in their fully retracted positions. Preferably, the extendible guide wires  180   a  and  180   b  are arranged to pass through the plurality of holes in the forward and rearward sections  150  and  160  at substantially uniform intervals so that the action of retracting the forward and rearward sections  150  and  160  into the pair of internal storage spaces  135   a  and  135   b  results in the forward section  150  and the rearward section  160  repetitively folding back upon themselves, in accordion fashion, to create a plurality of folds  195   a  and  195   b.    
     As shown in  FIG. 7 , a portion of the forward section  160  extends through the opening  125   a  in the shoulder pad  105  so that the distal end  153  of the forward section  150  remains on the outside of the internal storage space  135   a,  even when the forward section  150  is fully retracted. Likewise, a portion of the rearward section  160  extends through the other opening  125   b  of the shoulder pad  105  so that the distal end  163  of the rearward section  160  remains on the outside of the internal storage space  135   b,  even when the rearward section  160  is fully retracted. The fasteners  197   a  and  197   b,  which are attached to the distal ends  153  and  163  of the forward section  150  and rearward section  160 , respectively, permit the user to attach the shoulder strap  100  to corresponding hooks on a personal carrying device or receptacle (not shown in  FIG. 7 ), such as a purse, handbag, briefcase, satchel, athletic bag, duffle bag or suitcase. 
       FIG. 8  shows a cut-away view of an exemplary retractor  170  suitable for use with some embodiments of the present invention, wherein the top wall of the outer shell  172  of the retractor  170  has been removed to better illustrate the internal components of the retractor  170 . As shown in  FIG. 8 , the retractor  170  includes an extendible guide wire  180  that is attached to and configured to wrap around a rotatable spindle  175  (or spool) when the rotatable spindle  175  is rotated in a clockwise direction. A guide wire casing  181  is provided to receive and secure the coils of the extendible guide wire  180  as it is wrapped around the rotatable spindle  175 . A coiled spring  190 , which is coupled to the rotatable spindle  175 , applies a constant biasing force to the rotatable spindle  175  so that the rotatable spindle  175  will always tend to rotate in the clockwise direction, thereby causing the extendible guide wire  180  to retract into the guide wire casing  181  and wrap around the rotatable spindle  175 . However, the biasing force may be overcome by an external force (such as the weight of the briefcase, computer bag or other receptacle) that pulls on the distal end of the extendible guide wire  180 , thereby unwinding the extendible guide wire  180  from the rotatable spindle  175  and extracting the coils of the extendible guide wire  180  from the guide wire casing  181 . In alternative embodiments, such as the embodiment shown in  FIGS. 13 and 14 , the pair of retractors  170  may not include an outer shell  172 . 
     In preferred embodiments, the shoulder pad  105  is constructed from pieces of nylon material that are sewn together to form the base wall  110 , the cover  115 , the pair of internal storage spaces  135   a  and  135   b,  the retractor housing area  140  and the pair of openings  125   a  and  125   b.  However, other materials, such as cloth, fabric, leather, plastic, vinyl or rubber, may also be used to construct the shoulder pad  105 . In some embodiments, the shoulder pad  105  may be constructed from a combination of two or more of these materials. Ideally, the base wall  110  of the shoulder pad  105  also includes a pad or cushion constructed from a soft foam, rubber, silicone, or other material, to make the shoulder pad more comfortable as it sits on the user&#39;s shoulder. 
     The elongated strip  145  of pliant material serves as the strap component of the shoulder strap  100  of the present invention. The length, width and composition of the elongated strip  145  of pliant material of the strap can vary. In preferred embodiments, however, the elongated strip  145  is a continuous length of thin nylon approximately one inch in width and fifty inches in length. The elongated strip  145  may be fixedly secured to the shoulder pad  105  by various methods, such as by sewing the elongated strip  145  to the base wall  110  or the cover  115 . 
     In preferred embodiments, the extendible guide wires  180   a  and  180   b  are constructed from flexible lengths of nylon. However, the extendible guide wires  180   a  and  180   b  may also be constructed from a variety of other materials, including without limitation, metal, plastic, fabric, cloth, leather, natural fiber cord, string, or any combination of two or more of these materials. The distal ends of the extendible guide wires  180   a  and  180   b  are typically sewn into the distal ends  153  and  163  of the forward and rearward sections  150  and  160  of the elongated strip  145 . The purpose of the extendible guide wires  180   a  and  180   b  are to retract the forward and rearward sections  150  and  160  into the internal storage spaces  135   a  and  135   b  of shoulder pad  105 . The weight of the personal carrying device is supported by the elongated strip  145 . 
       FIGS. 9 and 10  show, respectively, how a user would typically use a retractable shoulder strap  100  constructed according to one embodiment of the present invention with a briefcase  102  (or other personal carrying device). To use the embodiment of the invention shown in  FIGS. 9 and 10 , the user first attaches the retractable shoulder strap  100  to the briefcase  102  (or other personal carrying device) by affixing the fasteners  197   a  and  197   b  to corresponding hooks on either end of the briefcase  102 . The user then grasps the center of the shoulder pad  105  and lifts upward. As the shoulder pad  105  is lifted upward, the weight of the briefcase  102  puts tension on the extendible guide wires  180   a  and  180   b,  which causes the forward and rearward sections  150  and  160  to be pulled out of the internal storage spaces  125   a  and  125   b  of the shoulder pad  105 . As this happens, the previously folded portions  195   a  and  195   b  of the forward and rearward sections  150  and  160  also begin to unfold as shown in  FIG. 9 . The user then places the shoulder pad  105  on his or her shoulder, with the forward section  150  facing the front of the user&#39;s body and the rearward section  160  facing the rear. When fully extended, the forward and rearward sections  150  and  160  will hang substantially straight down, as shown in  FIG. 10 , and take on the appearance and functionality of conventional non-retractable shoulder straps. 
     To retract the forward and rearward sections  150  and  160  of the shoulder strap  100 , the user grasps the center of the shoulder pad  105  and lifts the shoulder pad  105  off of the shoulder. Then the user places the briefcase on the floor or another surface before lowering the shoulder pad  105  toward the briefcase  102 . As the distance between the shoulder pad  105  and the briefcase  102  decreases, the tension on the extendible guide wires  180   a  and  180   b  is gradually removed. This causes the retractors  170   a  and  170   b  inside the shoulder pad  105  to retract the extendible guide wires  180   a  and  180   b  into their guide wire housings  181 , thereby causing the forward and rearward sections  150  and  160  to bend and fold back upon themselves so as to reproduce the folded portions  195   a  and  195   b.  As the extendible guide wires  180   a  and  180   b  continue retracting into the retractors  170   a  and  170   b,  the folded portions  195   a  and  195   b  are pulled through the openings  125   a  and  125   b  of the shoulder pad  105  and stowed in the internal storage spaces  135   a  and  135   b.  When the forward and rearward sections  150  and  160  are fully retracted, the base wall  110  of the shoulder pad  105  will rest neatly on the top surface of the briefcase  102  (see  FIG. 2 ). 
       FIGS. 11 and 12  show, respectively, a top perspective view and a bottom perspective view of an embodiment of a retractable shoulder strap constructed according to an alternative exemplary embodiment of the present invention, wherein the cover and the base wall of the shoulder pad are constructed from a flexible polymer material, the cover and the base wall comprising ridges and ribs to support flexibility. As shown best in  FIG. 12 , the cover  1205  is attached to the base wall  1210  by a plurality of screws  1215   a - 1215   d,  as opposed to the stitching or adhesive that might be used when the base wall and cover are constructed from a cloth or fabric material. As also shown in  FIG. 12 , the middle section  1217  of the elongated strip of pliant material is fixedly attached to the base wall  1210  with a plurality of screws  1220   a - 1220   d.    
       FIGS. 13 and 14  show, respectively, the embodiment of the retractable shoulder strap of  FIGS. 11 and 12 , with the cover of the shoulder pad removed to better illustrate the arrangement of the internal components of the shoulder pad. In  FIG. 13 , the forward and rearward sections of the elongated strip of pliant material in the strap are retracted and folded into the internal storage areas of the shoulder pad. In  FIG. 14 , the forward and rearward sections of the elongated strip of pliant material in the strap are extended and unfolded. Unlike the retractor  170  shown in  FIG. 8 , the pair of retractors  171   a  and  171   b  do not include retractor shells  172 . 
       FIG. 15  shows a portion of the rearward section  1505  of the elongated strip of pliant material, a portion of the forward section  1510  of the elongated strip, and the shoulder pad  1515  of the embodiment of the retractable should strap depicted in  FIGS. 11 through 14 . As shown in  FIG. 15 , the shoulder pad  1515  is configured to flex and bend over the arc of the user&#39;s shoulder  1520  while the shoulder strap is in use and the rearward section  1505  and forward section  1510  of the elongated strip of pliant material are extended. 
     Although the exemplary embodiments, uses and advantages of the invention have been disclosed above with a certain degree of particularity, it will be apparent to those skilled in the art upon consideration of this specification and practice of the invention as disclosed herein that alterations and modifications can be made without departing from the spirit or the scope of the invention, which are intended to be limited only by the following claims and equivalents thereof.