Patent Publication Number: US-9888761-B2

Title: Backpack with suspension arrangement

Description:
CROSS REFERENCE OF RELATED APPLICATION 
     This is a Continuation-In-Part application that claims priority to U.S. non-provisional application, application Ser. No. 15/076,622, filed Mar. 21, 2016, the entire contents of each of which are expressly incorporated herein by reference. 
    
    
     NOTICE OF COPYRIGHT 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to any reproduction by anyone of the patent disclosure, as it appears in the United States Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. 
     BACKGROUND OF THE PRESENT INVENTION 
     Field of Invention 
     The present invention relates to a backpack, and more particularly to a backpack with a suspension arrangement, which suspends the load at the backpack to minimize a continuous bounding movement/force of the backpack to the wearer&#39;s body when the wearers walks or runs. 
     Description of Related Arts 
     Backpacks generally comprises a bag body and two shoulder straps extended from the bag body, wherein the backpacks rely on the shoulder straps to carry the load at the bag body, the load exerts a backward pulling force at the shoulders of the wearer, causing back fatigue and strain. Especially, students, i.e. the wearers, often carry heavy books to and from school. Therefore, musculoskeletal experts are warning the parents that a young child often has an epidemic of back problems due to the continuous use of heavy backpack. According to the American Occupational Therapy Association, a student backpack should not weight more than 15 percent of the wearer&#39;s weight. When the wearer stands still, the loading force at the bag body is a static force equal to the weight of the load. However, when the wearer walks or runs, the loading force at the bag body is larger than the weight of the load. In particular, the loading force will change at all times during the body movement of the wearer. It is because the bag body will move up and down during the body movement of the wearer, wherein a gravity force is added into the weight of the load. In other words, the rapid or vigorous body movement of the wearer will dramatically increase the loading force at the bag body. For the wearers who need to carry heavy load, such as students, campers, hikers, or golfers, the loading force may not be evenly transferred to the shoulder straps. In other words, the center of mass of the wearer will shift during the body movement of the wearer, causing the wearer to trip or fail. 
     An improved backpack incorporates with a suspended loading device to minimize the up and down movement of the bag body. Accordingly, the suspended loading device comprises a suspension frame, wherein the shoulder straps are coupled at one side of the suspension frame and the bag body is movably coupled at another side of the suspension frame. Due to the relative movement between the bag body and the suspension frame, the up and down movement of the bag body can be minimized to transfer to the shoulder straps. However, such suspended loading device has several drawbacks. Accordingly, the suspension frame is relatively heavy added onto the weight of the bag body. Therefore, the overall weight of the backpack, including the load at the bag body and weight of the suspension frame, will directly exert to the wearer&#39;s body through the shoulder straps. In addition, more than one item is disposed in the bag body, which causes the uneven distribution of the weight of the bag body. However, the suspended loading device can only minimize the up and down movement of the bag body but cannot evenly distribute the loading force to the shoulder straps. As a result, the wearer&#39;s body will lean toward one side where the heavier load is exerted at one of the shoulder straps. 
     The conventional backpack further has a drawback that the bag body only has the top opening to communicate with the bag cavity in the bag body, wherein the top opening is defined at a top rim of the bag body. In particular, the bag body has an elongated shape that a length of the bag body is larger than a width thereof. As a result, the wearer will put or take the items in the bag cavity of the bag body through the top opening thereof. As a result, the wearer is unable to take the items at the bottom of the bag cavity through the top opening because the items at the bottom of the bag cavity are covered by and hidden under the items at the top of the bag cavity. In other words, the wearer must take out the items at the top of the bag cavity in order to access the bottom thereof. Furthermore, the wearer would like to carry a portable electronic device, such as laptop or tablet computer, by the backpack that the portable electronic device and different items are mixed and stored in the bag cavity. Even though the portable electronic device can be protected from any external force at the bag body, the portable electronic device is collided with the items within the bag body. It is worth mentioning that when the portable electronic device is taken out of the bag cavity, it is always a hard time for the wearer to put back the portable electronic device into the bag cavity at its original position. 
     SUMMARY OF THE PRESENT INVENTION 
     The invention is advantageous in that it provides a backpack with a suspension arrangement, which suspends the load at the backpack to minimize a continuous bounding movement/force of the backpack to the wearer&#39;s body when the wearers walks or runs. 
     Another advantage of the invention is to a backpack with a suspension arrangement, which comprises a resilient unit provided between a pack body and two shoulder straps for absorbing a bounding force of the pack body. Therefore, the resilient unit allows a relative movement of the pack body with respect to each of the shoulder straps but minimizes the relative movement of the pack body by absorbing the bounding force of the pack body. 
     Another advantage of the invention is to a backpack with a suspension arrangement, wherein the resilient unit is adapted for evenly distributing a loading force of the pack body to each of the shoulder straps, such that the resilient unit can absorb the bounding force of the pack body at different directions, such as an up-and-down direction or a lateral direction. 
     Another advantage of the invention is to a backpack with a suspension arrangement, wherein the suspension arrangement not only minimizes any up-and-down movement of the backpack but also reduces any sideward swinging movement of the backpack. 
     Another advantage of the invention is to a backpack with a suspension arrangement, wherein a tension of the resilient unit is adjustable to incorporate with the backpack depending on the load thereat. Therefore, the wearer is able to increase the tension of the resilient unit for carrying a heavier load at the backpack or decrease the tension of the resilient unit for carrying a lighter load at the backpack. 
     Another advantage of the invention is to a backpack with a suspension arrangement, wherein the pack body has an accessing arrangement for enlarging an opening area of the pack body, such that the wearer is able to easily access the bottom of the storage cavity via the enlarged opening area. 
     Another object of the present invention is to provide a backpack with a suspension arrangement, which does not require to alter the original structural design of the backpack, so as to minimize the manufacturing cost of the backpack incorporating with the suspension arrangement. 
     Another object of the present invention is to provide a backpack with a suspension arrangement, wherein no expensive or complicated structure is required to employ in the present invention in order to achieve the above mentioned objects. Therefore, the present invention successfully provides an economic and efficient solution for minimizing any continuous bounding movement/force of the backpack to the wearer&#39;s body when the wearers walks or runs so as to prevent the cause of the back fatigue and strain for the wearer. 
     Additional advantages and features of the invention will become apparent from the description which follows, and may be realized by means of the instrumentalities and combinations particular point out in the appended claims. 
     According to the present invention, the foregoing and other objects and advantages are attained by a backpack, comprising: 
     a pack body configured for being disposed on a wearer&#39;s back; 
     a carrying system which comprises two length-adjustable shoulder straps extended from the pack body for allowing the wearer to wear the pack body at the wearer&#39;s back; and 
     a suspension arrangement which comprises a resilient unit provided between the pack body and the shoulder straps for absorbing a bounding force of the pack body and for evenly distributing a loading force of the pack body to each of the shoulder straps so as to minimize a relative movement of the pack body with respect to each of the shoulder straps. 
     Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
     These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a rear perspective view of a backpack with a suspension arrangement according to a preferred embodiment of the present invention. 
         FIG. 2  is a side view of the backpack with the suspension arrangement worn by a wearer according to the above preferred embodiment of the present invention. 
         FIG. 3  is a perspective view of the suspension arrangement of the backpack according to the above preferred embodiment of the present invention. 
         FIG. 4  illustrates a first alternative mode of the suspension arrangement of the backpack according to the above preferred embodiment of the present invention, illustrating the detachable feature of the suspension arrangement. 
         FIG. 5  illustrates a second alternative mode of the suspension arrangement of the backpack according to the above preferred embodiment of the present invention, illustrating the tension adjustment of the suspension arrangement. 
         FIG. 6  illustrates a third alternative mode of the suspension arrangement of the backpack according to the above preferred embodiment of the present invention, illustrating the alternative tension adjustment of the suspension arrangement. 
         FIG. 7  illustrates a fourth alternative mode of the suspension arrangement of the backpack according to the above preferred embodiment of the present invention. 
         FIG. 8  illustrates a fifth alternative mode of the suspension arrangement of the backpack according to the above preferred embodiment of the present invention. 
         FIG. 9  is a front perspective view of a backpack with a suspension arrangement according to a second preferred embodiment of the present invention. 
         FIG. 10  is a rear perspective view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention. 
         FIG. 11  is a rear perspective view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention, illustrating a front detachable pocket coupled at the shoulder strap. 
         FIG. 12  is a left side view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention. 
         FIG. 13  is a right side perspective view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention. 
         FIG. 14  is a bottom view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention. 
         FIG. 15  is a partially perspective view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention, illustrating the front cavity, the rear cavity, and the front pocket of the pack body. 
         FIG. 16  is a front view of the backpack with the suspension arrangement according to the second preferred embodiment of the present invention, illustrating the enlarging slit. 
         FIG. 17  illustrates the strap fastening unit of the backpack according to the second preferred embodiment of the present invention. 
         FIG. 18  is a perspective view of a cover locker of the backpack according to the second preferred embodiment of the present invention. 
         FIG. 19  is a side view of the cover locker of the backpack according to the second preferred embodiment of the present invention. 
         FIG. 20  is a graph illustrating the loading force applied at the shoulders of the wearer by the present invention and the normal backpack. 
         FIG. 21  is a table illustrating the maximum pressure applied to the shoulders of the wearer with respect to the acceleration thereof for the present backpack and the normal backpack. 
         FIG. 22  illustrates the pressure on the shoulders of the wearer when wearing the conventional backpack. 
         FIG. 23  illustrates the pressure on the shoulders of the wearer when wearing the backpack of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description is disclosed to enable any person skilled in the art to make and use the present invention. Preferred embodiments are provided in the following description only as examples and modifications will be apparent to those skilled in the art. The general principles defined in the following description would be applied to other embodiments, alternatives, modifications, equivalents, and applications without departing from the spirit and scope of the present invention. 
     Referring to  FIGS. 1 and 2  of the drawings, a backpack according to a preferred embodiment of the present invention is illustrated, wherein the backpack, which is an ergonomic backpack, comprises a pack body  10 , a carrying system  20 , and a suspension arrangement  30 . 
     The pack body  10  is configured for being disposed on a wearer&#39;s back, wherein the pack body  10  has a storage cavity for receiving one or more items as a load of the pack body  10 , wherein the pack body  10  has a back side  11 . 
     The carrying system  20  comprises two length-adjustable shoulder straps  21  extended from the pack body  10  for allowing the wearer to wear the pack body  10  at the wearer&#39;s back. Preferably, the shoulder straps  21  are provided at the back side  11  of the pack body  10 . The carrying system  20  further comprises a handle loop  22  provided on a top side of the pack body  10 . Each of the shoulder straps  21  has a strap slide  210  to selectively adjust a length of the shoulder strap  21 . It is worth mentioning that the strap slide  210  can also allow the lower end of the shoulder strap  21  to be detached from the pack body  10 . 
     The suspension arrangement  30  comprises a resilient unit  31  provided between the pack body  10  and the shoulder straps  21 , wherein the resilient unit  31  allows a relative movement of the pack body  10  with respect to each of the shoulder straps  21 . Accordingly, the conventional backpack is constructed that the shoulder straps are affixed to the bag body, such that conventional backpack does not provide any means for allowing the relative movement of the bag body with respect to the shoulder straps. As a result, the loading force is directly exerted to the shoulder straps from the bag body. In view of the present invention, the resilient unit  31  provides a predetermined tension between the pack body  10  and the shoulder straps  21 , such that the pack body  10  can be relatively moved with respect to the shoulder straps  21 . 
     In particular, the resilient unit  31  of the present invention generates a predetermined resilient force between the pack body  10  and the shoulder straps  21  for absorbing a bounding force of the pack body  10 , especially when the wearers walks or runs, to minimize the relative movement of the pack body  10  with respect to each of the shoulder straps  21 . As it is mentioned above, if there is no relative movement of the pack body  10  with respect to the shoulder straps  21 , the loading force is directly exerted to the shoulder straps  21  from the pack body  10 . On the other hand, when there is a relative large movement of the pack body  10  with respect to the shoulder straps  21 , the bounding force of the pack body  10  will be varied in response to the movement of the pack body  10 , causing the backpack to be worn uncomfortably. Therefore, the resilient unit  31  of the present invention allows the relative movement of the pack body  10  with respect to each of the shoulder straps  21  but minimizes the relative movement of the pack body  10  by absorbing the bounding force of the pack body  10 . 
     The resilient unit  31  is also provided at the shoulder straps  21  individually for evenly distributing the loading force of the pack body  10  to each of the shoulder straps  21 , such that the resilient unit  31  can absorb the bounding force of the pack body  10  at different directions, such as an up-and-down direction or a lateral direction. For example, when the items are unevenly disposed in the pack body  10 , the loading force may not be exerted at a centerline of the pack body  10 . As a result, the loading force may be evenly distributed to the shoulder straps  21 . Since the resilient unit  31  of the present invention is provided at the shoulder straps  21  individually, the resilient unit  31  will generate the independent resilient force at each of the shoulder straps  21  to balance the uneven loading force at the pack body  10 , such that the loading force can be evenly distributed the loading force of the pack body  10  to each of the shoulder straps  21 . 
     As shown in  FIG. 1 , the resilient unit  31  comprises two resilient straps  311  extended from upper ends of the shoulder straps  21  respectively to the pack body  10 , wherein each of the resilient straps  311  provides the resilient force to absorb the bounding force of the pack body  10  to the respective shoulder strap  21 . In other words, the two resilient straps  311  provide the independent resilient forces at the shoulder straps  21  respectively to individually absorb the bounding force of the pack body  10 . 
     The resilient unit  31  further comprises two lower resilient straps  312  extended from lower ends of the shoulder straps  21  respectively to the pack body  10 , wherein the lower resilient straps  312  will also provide the resilient force to absorb the bounding force of the pack body  10  to the respective shoulder strap  21 . The resilient straps  311 ,  312  are made of stretchable material to generate the resilient force. Preferably, the resilient straps  311  are permanently affixed between the upper ends of the shoulder straps  21  and the pack body  10 , and the lower resilient straps  312  are permanently affixed between the lower ends of the shoulder straps  21  and the pack body  10 . It is worth mentioning that the strap slide  210  can also allow the lower end of the shoulder strap  21  to be detached from the lower resilient straps  312  so as to detach the lower end of the shoulder strap  21  from the pack body  10 . 
     Accordingly, the two resilient straps  311  at the upper ends of the shoulder straps  21  serve as two upper resilient straps  311 , such that each of the shoulder straps  21  is coupled to the pack body  10  via the upper resilient strap  311  and the lower resilient strap  312 . It is worth mentioning that the lower resilient straps  312  will pull the back side  11  of the pack body  10  close to the back of the wearer when the backpack is worn to ensure the weight of the pack body  10  to close to the center of mass of the wearer. In addition, the upper and lower resilient straps  311 ,  312  will provide the resilient forces at different directions of the pack body  10  for not only minimizing any up-and-down movement of the backpack but also reducing any sideward swinging movement of the backpack. 
     As shown in  FIG. 3 , in order to secure the resilient straps  311  at the pack body  10 , the suspension arrangement  30  further comprises two extension tongues  32  extended from the back side  11  of the pack body  10 , wherein the resilient straps  311  are extended between the upper ends of the shoulder straps  21  and the extension tongues  32  respectively. Preferably, the extension tongues  32  are permanently and securely affixed to the back side  11  of the pack body  10  at a top edge thereof by stitching. It is worth mentioning that the two extension tongues  32  ensure the direction of force to be transferred. In particular, the two extension tongues  32  ensure the loading force at the pack body  10  to be transferred along the resilient straps  311 . 
     As shown in  FIG. 3 , each of the resilient straps  311  has a rectangular shape that a width of an upper edge is the same as a width a lower edge, wherein the upper edge of the resilient strap  311  is extended from the extension tongue  32  and the lower edge of the resilient strap  311  is extended from the upper end of the shoulder strap  21 . This uniform width of the resilient strap  31  will ensure the loading force to be transferred to the shoulder strap  21 . In addition, the resilient force at the upper edge of the resilient strap  311  is the same as the resilient force at lower edge of the resilient strap  311  to ensure the uniform resilient force thereat to support the pack body  10 . Preferably, the upper edge of the resilient strap  311  is permanently affixed to the extension tongue  32  by stitching and the lower edge of the resilient strap  311  is permanently affixed to the upper end of the shoulder strap  21  by stitching. 
     In addition, the suspension arrangement  30  further comprises two receiving sleeves  33  extended from the pack body to the upper ends of the shoulder straps  21  to receive the resilient straps  311  within the receiving sleeves  33  respectively in a hidden manner, as shown in  FIG. 3 . Each of the receiving sleeves  33  has a tubular shape to receive the resilient strap  311 . Accordingly, the upper ends of the shoulder straps  21  are also received in the receiving sleeves  33  in a hidden manner. It is worth mentioning that the upper edges of the receiving sleeves  33  are affixed to secure the receiving sleeves  33  and the lower edges of the receiving sleeves  33  are non-stitched, such that the upper ends of the shoulder straps  21  can be freely slid within the receiving sleeves  33  respectively to allow the resilient straps  311  to be stretched correspondingly. 
     In particular, a length of each of the receiving sleeves  33  is long enough to cover the maximum length of the resilient strap  311  that the resilient strap  311  is stretched in a maximum condition between the upper edge and the lower edge. Therefore, when the backpack is worn by the wearer, the two resilient straps  311  are hidden and cannot be seen. Preferably, the two receiving sleeves  33  are extended from the extension tongues  33 , preferably affix to the extension tongues  33 , to the upper ends of the shoulder straps  21  to receive the resilient straps  311  within the receiving sleeves  33  respectively in a hidden manner. 
     According to the preferred embodiment, the tension of the resilient unit  31  should be increased for carrying a heavier load at the backpack or decreased for carrying a lighter load at the backpack.  FIG. 4  illustrates a first alternative mode of the suspension arrangement  30 A to allow the user to adjust the tension of the resilient unit  31 A. As shown in  FIG. 4 , the resilient straps  311 A is detachably affixed to the pack body  10 , such that the user is able to change different resilient straps  311 A with different tensions corresponding to the load of the backpack. 
     Accordingly, the suspension arrangement  30 A further comprises two first strap fasteners  351 A extended from the back pack  10  and two second strap fasteners  352 A provided at the resilient straps  311 A respectively, wherein the first strap fasteners  351  are detachably coupled with the second strap fasteners  352 A to detachably couple the resilient straps  311 A at the pack body  10 . It is worth mentioning that the upper edge of the resilient strap  311 A is coupled to the second strap fastener  352 A and the lower edge of the resilient strap  311 A is extended from the upper end of the shoulder strap  21 . Preferably, the first strap fasteners  351  are coupled at the extension tongues  32 A respectively. Preferably, the first and second strap fasteners  351 A,  352 A are quick release buckle clip mechanism. It is appreciated the first and second strap fasteners  351 A,  352 A can be other fastening mechanisms such as snap hooks for detachably affixing the resilient straps  311 A to the pack body  10 . It is worth mentioning that the receiving sleeves  33  can be incorporated with this detachably affixing structure to cover the first and second strap fasteners  351 A,  352 A. 
       FIG. 5  illustrates a second alternative mode the suspension arrangement  30 B to allow the user to adjust the tension of the resilient unit  31 B via a tension adjusting unit  35 B. In particular, the user is able to adjust selectively adjust the tension of each of said resilient straps  311 B via the tension adjusting unit  35 B. As shown in  FIG. 5 , the tension adjusting unit  35 B comprises a first adjusting fastener  351 B provided at the pack body  10 , a second adjusting fastener  352 B provided at each of the shoulder straps  21 , and a tension adjustor  353 B detachably fastening the first and second adjusting fasteners  351 B,  352 B to selectively adjust the tension of the respective resilient strap  311 B. Preferably, two first adjusting fasteners  351 B are provided at the extension tongues  32 B respectively and two second adjusting fastener  352 B are provided at the upper ends of the shoulder straps  21  respectively. Therefore, the tension of each of said resilient straps  311 B can be selectively adjusted via the tension of the tension adjustor  353 B. 
     Accordingly, when the tension adjustor  353 B is made of non-stretchable material to serve as a non-stretchable member  354 B detachably fastening the first and second adjusting fasteners  351 B,  352 B, the distance between the pack body  10  and the upper end of the shoulder strap  21  is fixed to restrict the respective resilient strap  311 B to be stretched. When the tension adjustor  353 B is made of stretchable material to serve as a stretchable member  355 B detachably fastening the first and second adjusting fasteners  351 B,  352 B, the tension adjustor  353 B has a predetermined tension added on to each of the resilient straps  311 B. Therefore, the overall tension of the resilient strap  311 B and the tension adjustor  353 B will be increased for carrying a heavier load of the pack body  10 . Preferably, the first and second adjusting fasteners  351 B,  352 B are two buttons, wherein two button holes are formed at two end portions of the tension adjustor  353 B to detachably fasten the tension adjustor  353 B with the first and second adjusting fasteners  351 B,  352 B. It is appreciated that different fasteners can be used for detachably fastening the tension adjustor  353 B between the pack body  10  and the shoulder strap  21 . Therefore, depending the load of the pack body  10 , the user is able to change different tension adjustors  353 B to adjust selectively adjust the tension of each of said resilient straps  311 B. 
       FIG. 6  illustrates a third alternative mode the suspension arrangement  30 C to allow the user to adjust the tension of the resilient unit  31 C via a tension adjusting unit  35 C. As shown in  FIG. 6 , each of the shoulder straps  21 C comprises a cushioning sleeve  211 C defining an inner cushioning layer  212 C and an outer cushioning layer  213 C overlapped thereon, wherein a sliding cavity  214 C is formed between said inner and outer cushioning layers  212 C,  213 C and a top opening  215 C formed at the upper end of the shoulder straps  21 C to communicate with the sliding cavity  214 C. 
     Each of the resilient straps  311 C is extended from the pack body  10  to slidably receive in the cushioning sleeve  211 C. In particular, each of the resilient straps  311 C is securely extended from the extension tongues  32 C at the pack body  10  to slidably receive within the sliding cavity  214 C through the top opening  215 C. 
     The tension adjusting unit  35 C comprises a plurality of first tension fasteners  351 C spacedly formed at each of the resilient straps  311 C and a second tension fastener  352 C formed at the cushioning sleeve  211 C to selectively fasten with one of the first tension fasteners  351 C so as to selectively adjust the tension of the resilient strap  311 C. Accordingly, the first tension fasteners  351 C are embodied as a plurality of first button holes spacedly formed along the resilient straps  311 C. The second tension fastener  352 C comprises a fastening button provided at the cushioning sleeve  211 C to selectively fasten with one of the first button holes to detachably affix the resilient strap  311 C at the cushioning sleeve  211 C. Preferably, the second tension fastener  352 C further has a second button hole formed at the outer cushioning layer  213 C, wherein the fastening button is provided at the inner cushioning layer  212 C to align with the second button hole. Therefore, when the resilient strap  311 C is slid within the sliding cavity  214 C to selectively align the second button hole with one of the first button holes, the fastening button is fastened with the first and second button holes to affix the resilient strap  311 C at the cushioning sleeve  211 C. As the longer length of the resilient strap  311 C being exposed out of the cushioning sleeve  21 C, the tension of the resilient strap  311 C will be increased. In other words, the wearer is able to increase the tension of each of the resilient straps  311 C by lengthening the portion of the resilient strap  311 C exposed out of the cushioning sleeve  211 C and is able to reduce the tension of each of the resilient straps  311 C by shortening the portion of the resilient strap  311 C exposed out of the cushioning sleeve  211 C. It is worth mentioning that the receiving sleeves  33  can be incorporated with this detachably affixing structure that the receiving sleeve  33  is extended to cover the top opening  215 C of each of the cushioning sleeve  211 C of the shoulder strap  211 C. 
       FIG. 7  illustrates a fourth alternative mode the suspension arrangement  30 D to allow the user to adjust the tension of the resilient unit  31 D. Accordingly, the suspension arrangement  30 D further comprises a back supporting member  36 D detachably coupled to the back side  11  of the pack body  10 , wherein the resilient unit  31 D is provided between the back supporting member  36 D and the shoulder straps  21 . 
     As shown in  FIG. 7 , the back supporting member  36 D comprises an elongated attachment member  361 D extended between two upper ends of the resilient straps  311 D in a transverse direction, such that the resilient straps  311 D and the attachment member  361 D form an inverted “U” shaped configuration. Accordingly, when the attachment member  361 D is detachably coupled at the pack body  10 , the upper ends of the resilient straps  311 D are coupled at the back side of the pack body  10 . Preferably, the attachment member  361 D is made of rigid but light weight material. 
     The pack body  10  further comprises a receiving pocket  12 D formed at the back side  11  of the pack body  10  to receive the back supporting member  36 D. As shown in  FIG. 7 , the receiving pocket  12 D is formed at the top edge of the pack body  10 . In particular, the receiving pocket  12 D comprises a pocket leaf  121 D having one affixing edge firmly affixed to the pack body  10  and an opposed detachable edge detachably coupling at the back side  11  of the pack body  10  to overlap the pocket leaf  121 D thereon so as to form a pocket cavity between the pocket leaf  121 D and the back side  11  of the pack body  10 . The width of the pocket leaf  121 D is slightly smaller than a length of the attachment member  361 D, such that the attachment member  361 D can be tightly wrapped within the pocket cavity of the pocket leaf  121 D. It is appreciated that the detachable edge of the pocket leaf  121 D can be detachably coupled at the back side  11  of the pack body  10  via snap buttons, button and button hole attachment, hook and loop fasteners, zippers, or the like. Therefore, the wearer is able to change the resilient unit  31 D by detaching the resilient unit  31 D from the receiving pocket  12 D and by re-attaching the desired resilient unit  31 D with proper tension thereof to the receiving pocket  12 D. 
       FIG. 8  illustrates another alternative mode the back supporting member  36 E of the suspension arrangement  30 E to allow the user to adjust the tension of the resilient unit  31 E. The back supporting member  36 E comprises a cushioning panel  361 E shaped and sized corresponding to the back side  11  of the pack body  10 , wherein the resilient straps  311 E are extended from the cushioning panel  361 E. In addition, the shoulder straps  21  are also extended from the cushioning panel  361 E to affix with the resilient straps  311 D respectively. As shown in  FIG. 8 , the cushioning panel  361 E is detachably coupled at the back side  11  of the pack body  10 . Accordingly, a peripheral edge portion of the cushioning panel  361 E is detachably coupled at a peripheral edge portion of the back side  11  of the pack body  10  via a fastening means. Preferably, the fastening means can be a zipper. Alternatively, the fastening means can be snap buttons, button and button hole attachment, hook and loop fasteners, or the like. Therefore, the wearer is able to change the resilient unit  31 E by detaching the cushioning panel  361 E from the pack body  10  and by re-attaching the cushioning panel  361 E with the desired tension of the resilient unit  31 E to the back side  11  of the pack body  10 . 
     As shown in  FIGS. 9 to 15 , a backpack according to a second embodiment illustrates an alternative mode of the first embodiment, wherein the backpack comprises a pack body  10 F, a carrying system  20 F, and a suspension arrangement  30 F. 
     The pack body  10 F, which is made of durable and waterproof material, has an elongated shape that a length of the pack body  10 F is larger than a width thereof. The pack body  10 F has a storage cavity  101 F for receiving one or more items as a load of the pack body  10 F, and a top opening  102 F, wherein the pack body  10 F comprises a back panel  11 F, a front panel  12 F, two side panels  13 F and a bottom panel  17 F to define the storage cavity  101 F within the back panel  11 F, the front panel  12 F, the side panels  13 F, and the bottom panel  17 F. Preferably, the bottom panel  17 F is made of EVA (Ethylene Vinyl Acetate) material. Cushioning pads are provided at the back panel  11 F. The pack body  10 F further comprises an opening cover  14 F foldably extended from the rear panel  11 F of the pack body  10 F to the front panel  12 F thereof for covering the top opening  102 F and enclosing the storage cavity  101 F. Therefore, the opening cover  14 F can be upwardly flipped to open up the top opening  102 F. 
     As shown in  FIGS. 9, 18 and 19 , the pack body  10 F further comprises a cover locker  16 F releasably coupled the opening cover  14 F at the front panel  12 F. Accordingly, the cover locker  16 F comprises a first locker member  161 F provided at a front edge of the opening cover  14 F and a second locker member  162 F provided at the front panel  12 F to detachably couple with the first locker member  161 F. In particular, the second locker member  162 F is overlapped and engaged with the first locker member  161 F. The first locker member  161 F comprises a first magnetic element  163 F and a U-shaped resilient locker  164 F, wherein the first magnetic element  163 F is located within the U-shaped resilient locker  164 F. The second locker member  162 F comprises a tapered locking head  165 F with a second magnetic element  166 F embedded therein, wherein the tapered locking head  165 F has an enlarged head portion with a slanted circumferential surface, and a narrowed neck portion downwardly extended from the enlarged head portion. When the second magnetic element  166 F is magnetically attracted with the first magnetic element  163 F, the U-shaped resilient locker  164 F is expanded to slide at the tapered locking head  165 F until the U-shaped resilient locker  164 F is engaged with the neck portion of the tapered locking head  165 F. It is worth mentioning that the magnetic attracting force between the first magnetic element  163 F and the second magnetic element  166 F will force the U-shaped resilient locker  164 F to expand and to slide at the tapered locking head  165 F. Therefore, the second locker member  162 F is overlapped and engaged with the first locker member  161 F. Accordingly, in order to unlock the cover locker  16 F, the second locker member  162 F must be sidewardly slid to disengage with the first locker member  161 F. Since the U-shaped resilient locker  164 F is engaged with the neck portion of the tapered locking head  165 F, the U-shaped resilient locker  164 F cannot be directly pulled to disengage with the tapered locking head  165 F. Therefore, the tapered locking head  165 F must be slid out of an opening of the-shaped resilient locker  164 F in order to disengage the U-shaped resilient locker  164 F with the tapered locking head  165 F. In other words, the direction of unlocking the cover locking  16 F is different from the direction of folding the opening cover  14 F to open up the top opening  102 F. Therefore, the opening cover  14 F will not be accidentally opened by unintentionally unlocking the cover locker  16 F. 
     The pack body  10 F further comprises an accessing arrangement  15 F for accessing the storage cavity  101 F. The accessing arrangement  15 F comprises a partition wall  151 F provided in the storage cavity  101 F to partition the storage cavity  101 F into a front cavity  103 F and a rear cavity  104 F. Preferably, four edges of the partition wall  151 F are affixed to the back panel  11 F, the front panel  12 F and the side panels  13 F, such that the front cavity  103 F and the rear cavity  104 F are two discrete cavities that no access can be formed therebetween. It is worth mentioning that the top opening  102 F communicate with the front cavity  103 F, wherein when the opening cover  14 F is upwardly flipped, only the front cavity  103 F is opened up. In order to access the rear cavity  104 F, the accessing arrangement  15 F further comprises a side opening  152 F formed on at least one of the side panels  13 F to communicate with the rear cavity  104 F, and a side fastener  153 F provided at the corresponding side panel  13 F at the side opening  152 F to selectively close the side opening  152 F. In one embodiment, the side fastener  153 F is a zipper formed at the edges of the side opening  152 F to open or close the side opening  152 F. Preferably, an upper end of the side opening  152 F is extended close to an upper edge of the side panel  13 F and the lower end of the side opening  152 F is extended close to a lower edge of the side panel  13 F. Therefore, when the side fastener  153  is actuated to open up the side opening  152 F, the wearer is able to fully access the rear cavity  104 F. Accordingly, a portable electronic device, such as laptop or tablet computer, can be stored and protected in the rear cavity  104 F since the rear cavity  104 F cannot access to the front cavity  103 F. 
     In one embodiment, a volume of the front cavity  103 F is larger than a volume of the rear cavity  104 F. In order to allow the wearer to easily access the bottom of the front cavity  103 F, the accessing arrangement  15 F further comprises an enlarging slit  154 F extended from the top opening  102 F to enlarge an opening area of the front cavity  103 F, and an enlarging fastener  155 F provided at the enlarging slit  154 F. Accordingly, the enlarging slit  154 F is formed at a side edge of the front panel  12 F, wherein when the enlarging fastener  155 F is actuated to open up the enlarging slit  154 F, the opening area of the front cavity  103 F is enlarged by the top opening  102 F and the enlarging slit  154 F. Therefore, the wearer is able to access the bottom of the front cavity  103 F through the enlarged opening area. It is worth mentioning that the wearer is able to access the upper section of the front cavity  103 F through the top opening  102 F when the enlarging slit  154 F is closed. Preferably, the enlarging fastener  155 F is also a zipper. 
     It is appreciated that the pack body  10 F further has a front pocket  105 F formed behind the front panel  12 F and in front of the front cavity  103 F, wherein the top opening  102 F serves as a common opening for the front pocket  105 F and the front cavity  103 F. In other words, the opening cover  14 F is folded to close the top opening  102 F in order to enclose the front pocket  105 F and the front cavity  103 F at the same time. Likewise, the accessing arrangement  15 F further comprises a front slit  156 F extended from the top opening  102 F to enlarge an opening area of the front pocket  105 F, and a front fastener  157 F provided at the front slit  156 F. Accordingly, the front slit  156 F has a L-shape or U-shape formed at the front panel  12 F, wherein when the front fastener  157 F is actuated to open the front slit  156 F, the front panel  12 F can be frontwardly flipped to open up the front pock  105 F. The front fastener  157 F is also a zipper. 
     The carrying system  20 F comprises two shoulder straps  21 F extended from the pack body  10 F for allowing the wearer to wear the pack body  10 F at the wearer&#39;s back. Preferably, the shoulder straps  21 F are provided at the back panel  11 F of the pack body  10 F. A front detachable pocket  18 F is provided to detachably couple at one of the shoulder straps  21 F. 
     The suspension arrangement  30 F comprises a resilient unit  31 F provided between the pack body  10 F and the shoulder straps  21 F, wherein the resilient unit  31 F allows a relative movement of the pack body  10 F with respect to each of the shoulder straps  21 F. Accordingly, the resilient unit  31 F provides a predetermined tension between the pack body  10 F and the shoulder straps  21 F, such that the pack body  10 F can be relatively moved with respect to the shoulder straps  21 F. 
     As shown in  FIGS. 10 and 11 , the resilient unit  31 F comprises two resilient straps  311 F extended from upper ends of the shoulder straps  21 F respectively to the pack body  10 F, wherein each of the resilient straps  311 F provides the resilient force to absorb the bounding force of the pack body  10 F to the respective shoulder strap  21 F. In other words, the two resilient straps  311 F provide the independent resilient forces at the shoulder straps  21 F respectively to individually absorb the bounding force of the pack body  10 F. 
     The suspension arrangement  30 F further comprises two receiving sleeves  33 F extended from the pack body  10 F to the upper ends of the shoulder straps  21 F to receive the resilient straps  311 F within the receiving sleeves  33 F respectively in a hidden manner, as shown in  FIGS. 10 and 11 . Each of the receiving sleeves  33 F has a tubular shape to receive the resilient strap  311 F. Accordingly, each of the receiving sleeves  33 F, having a bellow shape, has an upper end coupled to the pack body  10 F and a lower end coupled to the upper end of the shoulder strap  21 F, such that the resilient straps  311 F is received along the receiving sleeve  33 F in a hidden manner. It is worth mentioning that the bellow shaped receiving sleeve  33 F allows the resilient straps  311 F to be stretched correspondingly. In other words, a length of each of the receiving sleeves  33 F is long enough to cover the maximum length of the resilient strap  311 F that the resilient strap  311 F is stretched in a maximum condition between the upper edge and the lower edge. Therefore, when the backpack is worn by the wearer, the two resilient straps  311 F are hidden and cannot be seen. 
     The resilient unit  31 F further comprises two lower resilient straps  312 F extended from lower ends of the shoulder straps  21 F respectively to the pack body  10 F, wherein the lower resilient straps  312 F will also provide the resilient force to absorb the bounding force of the pack body  10 F to the respective shoulder strap  21 F. The resilient straps  311 F,  312 F are made of stretchable material to generate the resilient force. Preferably, the resilient straps  311 F are permanently affixed between the upper ends of the shoulder straps  21 F and the pack body  10 F, and the lower resilient straps  312 F are detachably affixed between the lower ends of the shoulder straps  21 F and the pack body  10 F. 
     Accordingly, the lower resilient strap  312 F is detachably and slidably coupled to the lower end of the shoulder strap  21 F via a strap slide  210 F. The strap slide  210  can allow the lower end of the shoulder strap  21 F to be detached from the lower resilient strap  312 F so as to detach the lower end of the shoulder strap  21  from the pack body  10 F. The strap slide  210 F is provided at the lower end of each of the shoulder straps  21 F. The strap slide  201 F can also allow a usage length of the lower resilient strap  312 F, i.e. a distance between the pack body  10 F and the lower end of the shoulder strap  21 F, to be selectively adjusted. It is worth mentioning that when the usage length of the lower resilient strap  312 F is decreased, the lower resilient strap  312 F will generate lesser resilient force, and when the usage length of the lower resilient strap  312 F is increased, the lower resilient strap  312 F will generate larger resilient force. 
     As shown in  FIGS. 10 to 14 and 17 , the suspension arrangement  30 F further comprises a strap fastening unit  35 F for detachably coupling each of the lower resilient straps  312 F at the pack body  10 F. The strap fastening unit  35 F comprises two first strap fasteners  351 F extended from the back pack  10 F and two second strap fasteners  352 F provided at the lower ends of the lower resilient straps  312 F respectively, wherein the first strap fasteners  351 F are detachably coupled with the second strap fasteners  352 F to detachably couple the lower resilient straps  312 F at the pack body  10 F. 
     Each of the first strap fasteners  351 F comprises first and second fastener panels  353 F,  354 F defining a sliding gap  355 F therebetween and an engaging through slot  356 F formed at the first fastener panel  353 F to communicate with the sliding gap  355 F. Each of the second strap fasteners  352 F comprises a sliding panel  357 F slidably inserted into the sliding gap  355 F and a resilient engaging member  358 F flexibly protruded from the sliding panel  357 F to engage with the engaging through slot  356 F when the sliding panel  357 F is slid into the sliding gap  355 F to detachably couple the second strap fastener  352 F with the first strap fastener  351 F. In order to detach the second strap fastener  352 F from the first strap fastener  351 F, the resilient engaging member  358 F is pressed on the sliding panel  357 F to disengage with the engaging through slot  356 F, such that the sliding panel  357 F is slid out of the sliding gap  355 F. It is worth mentioning that the engaging through slot  356 F is a circular through hole and the resilient engaging member  358 F has a circular shape. Therefore, when the resilient engaging member  358 F is engaged with the engaging through slot  356 F, the sliding panel  357 F can be rotated at the sliding gap  355 F to rotatably couple the second strap fastener  352 F with the first strap fastener  351 F. In other words, the strap fastening unit  35 F not only provides a detachable feature for detachably coupling each of the lower resilient straps  312 F at the pack body  10 F but also serves as a rotatable point for rotatably coupling each of the lower resilient straps  312 F at the pack body  10 F. 
     As a result, the lower resilient straps  312 F is detachably affixed to the pack body  10 F, such that the user is able to change different lower resilient straps  312 F with different tensions corresponding to the load of the backpack. 
       FIGS. 20, 22, and 23  illustrates the loading force applied at the shoulders of the wearer by the present invention and the normal backpack (conventional backpack). Assuming that the acceleration of the wear is about 5.2 mph (mile per hour), the wearer wears the present backpack and the normal backpack respectively loaded with the same weight (10 lb). When the wearer is stationary, i.e. not moving, the loading force applied at the shoulders of the wearer through the shoulder straps of the present invention is the same as the loading force applied at the shoulders of the wearer through the shoulder straps of the normal backpack. 
     When the wearer walks or runs, the backpack will moved up and down according to the step movement of the wearer. Assumed that the value of upward acceleration of the backpack is positive and the value of the downward acceleration of the backpack is negative. When the wearer&#39;s body moves up during walks or runs, the value of acceleration of the normal backpack is negative from point A to point B to point C, wherein the point B is a bottom peak and has the maximum valve of the upward acceleration of the normal backpack. In other words, the maximum loading force applied at the shoulders of the wearer through the shoulder straps of the normal backpack is defined at the point B according to the upward movement of the wearer. When the wearer&#39;s body moves down during walks or runs, the value of acceleration of the normal backpack is positive from point C to point D to point E, wherein the point D is a top peak and has the maximum valve of the downward acceleration of the normal backpack. In other words, the maximum loading force applied at the shoulders of the wearer through the shoulder straps of the normal backpack is defined at the point D according to the downward movement of the wearer. Then, the wearer&#39;s body will move up again during walks or runs, wherein the value of acceleration of the normal backpack is negative from point E to point F to point G. Therefore, the point F is another bottom peak and has the maximum valve of the upward acceleration of the normal backpack. 
     Comparing the top peaks and the bottom peaks of the loading forces at the present backpack and the normal backpack, the top peaks of the loading forces for the present backpack are lower than the top peaks of the loading forces for the normal backpack, and the bottom peaks of the loading forces for the present backpack are higher than the bottom peaks of the loading forces for the normal backpack. It means that the loading forces applied to the shoulders of the wearer via the present backpack are smaller than the loading forces applied to the shoulders of the wearer via the normal backpack. In addition, the amplitudes of the loading forces of the present backpack is smaller than the amplitudes of the loading forces of the normal backpack, such that the present backpack can be stably worn by the wearer comparing with the normal backpack by minimizing the up-and-down movement of the backpack. 
     Furthermore,  FIG. 20  also illustrates the loading time for the downward loading force applied on the shoulders of the wearer, wherein the pressure on the shoulders of the wearer will be increased via the downward loading force when the loading time is prolonged, and the pressure on the shoulders of the wearer will be reduced via the downward loading force when the loading time is shortened. 
     An acceleration sensor is utilized for determining the acceleration of the backpack for a time interval of 1/50 second. The loading time for the loading force applied on the shoulders of the wearer via the normal backpack is 0.08 second. The loading time for the loading force applied on the shoulders of the wearer via the present backpack is 0.12 second. Therefore, the present invention provides a better buffering than the normal backpack. 
       FIG. 21  is a table illustrating the maximum pressure applied to the shoulders of the wearer with respect to the acceleration thereof. For example, a miniature force sensor is placed in each of the present backpack and the normal backpack for determining the maximum pressures thereat, wherein the present backpack and the normal backpack are respectively loaded with the same weight (10 lb), as shown in  FIGS. 22 and 23 . Comparing the acceleration values from 3 mph to 8 mph, the maximum pressures applied to the shoulders of the wearer by the present backpack are smaller than the maximum pressures applied to the shoulders of the wearer by the normal backpack. Therefore, from  FIGS. 20 to 23 , the loading force applied at the shoulders of the wearer through the shoulder straps of the present invention is smaller than the loading force applied at the shoulders of the wearer through the shoulder straps of the normal backpack, so as to minimize a continuous bounding movement/force of the backpack to the wearer&#39;s body when the wearers walks or runs. 
     Accordingly, all the features in the above preferred embodiment and its alternatives are interchangeable to achieve the objective of the present invention. In particular, the two resilient straps are made of elastic fabric to provide a predetermined tension to absorb the bounding force of the load at the backpack. The tension of each resilient strap will be self-adjusted corresponding to the load at the backpack to ensure the loading force to be evenly distributed at the shoulder straps. Therefore, the present invention provides a simple but effective configuration for minimizing any continuous bounding movement/force of the backpack to the wearer&#39;s body when the wearers walks or runs so as to prevent the cause of the back fatigue and strain for the wearer. 
     One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting. 
     It will thus be seen that the objects of the present invention have been fully and effectively accomplished. The embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.