in conventional backpacks , comfort is not optimized even when comfort - enhancing features are incorporated into the backpack . the novel arrangement , positioning , and dimensions of features in the ergonomic backpacks with enhanced fit described in this application provide a user with optimal fit and comfort . fig1 - 6 illustrate examples of the present invention designed as unisex backpacks . fig7 - 8 illustrate examples of the present invention designed specifically for women . fig1 illustrates an ergonomic backpack with enhanced fit 100 . backpack 100 includes a storage portion 102 that includes one or more compartments capable of storing cargo . storage portion 102 has a top side 104 , a bottom side 106 , a left side 108 , and a right side 110 . when backpack 100 is worn by a user ( as illustrated in fig2 - 3 ), top side 104 is nearer to the user &# 39 ; s head than bottom side 106 , bottom side 106 is nearer to the user &# 39 ; s legs than top side 104 , left side 108 is nearer to the user &# 39 ; s left shoulder than right side 110 , and right side 110 is nearer to the user &# 39 ; s right shoulder than left side 108 . storage portion 102 is connected to a first end 112 of a primary left shoulder strap 114 along a first connection area 116 . first connection area 116 is on the top and left side of storage portion 102 . storage portion 102 is also connected to a first end ( not shown ) of a primary right shoulder strap 118 along a second connection area ( not shown ). the second connection area is on the top and right side of storage portion 102 . secondary left shoulder strap 120 is attached at a first end 122 to the bottom and left side of storage portion 102 . secondary left shoulder strap 120 is also connected to a second end 124 of primary left shoulder strap 114 . similarly , secondary right shoulder strap 126 is attached at a first end 128 to the bottom and right side of storage portion 102 . secondary right shoulder strap 126 is also connected to a second end 130 of primary right shoulder strap 118 . fig1 illustrates buckles 132 and 134 connecting primary left shoulder strap 114 and primary right shoulder strap 118 to their respective secondary shoulder straps . any number of connecting devices or techniques may be used to facilitate these connections . in some examples , the connections are detachable and / or adjustable . fig2 illustrates ergonomic backpack with enhanced fit 100 while being worn by a user 200 . primary left shoulder strap 114 is worn over the user &# 39 ; s left shoulder 202 , and primary right shoulder strap 118 is worn over the user &# 39 ; s right shoulder 204 . to better illustrate some of the novel features of the invention , fig3 - 8 show examples of an ergonomic backpack with enhanced fit with the primary and secondary shoulder straps not connected and the primary straps raised such that they extend upward and away from the body of a user wearing the backpack . as stated above , in some examples the primary and secondary shoulder straps may be detachable . fig3 - 8 are also intended to illustrate examples in which the primary and secondary shoulder straps are not detachable , even though the primary and secondary straps are shown not connected for illustration purposes . fig3 illustrates a user 300 wearing ergonomic backpack 100 . a dashed line represents a vertical plane 302 extending through the body of user 300 . primary right shoulder strap 118 and primary left shoulder strap 114 ( not shown ) are raised such that primary right shoulder strap 118 and primary left shoulder strap 114 extend upward from the body of user 300 and are substantially parallel with vertical plane 302 . primary right shoulder strap 118 and primary left shoulder strap 114 also extend away from the center of backpack 100 when the primary straps are in this position , as is clearly illustrated in fig4 - 8 . fig3 is intended for illustration purposes . it should be appreciated that gravitational force would cause backpack 100 to fall off of user 300 if user 300 attempted to wear backpack 100 with the primary straps in a raised , substantially vertical position as shown . fig3 establishes a frame of reference for a more complete discussion of the novel features of backpack 100 in subsequent figures . fig4 is a plan view of backpack 100 looking at the surface of backpack 100 that rests against a user &# 39 ; s back . primary shoulder straps 114 and 118 are raised to a substantially vertical position as shown in fig3 . secondary shoulder straps 120 and 126 are also shown , and storage portion 102 is shown as a dotted line so as to not distract from the explanation of novel features of backpack 100 . as discussed with regard to fig1 , first end 112 of primary left shoulder strap 114 is connected to storage portion 102 along first connection area 116 . first end 402 of primary right shoulder strap 118 is connected to storage portion 102 along second connection area 404 . first connection area 116 and second connection area 404 are each spaced approximately the same distance from a substantially vertical bisecting line 406 extending through backpack 100 from top side 104 to bottom side 106 . first connection area 116 and second connection area 404 are substantially collinear with a substantially horizontal line 408 extending across top side 104 of backpack 100 . primary left shoulder strap 114 connects to first connection area 116 and primary right shoulder strap 118 connects to second connection area 404 at substantially equal angles relative to substantially horizontal line 408 . in some examples , the material comprising primary shoulder straps 114 and 118 extends beyond connection areas 116 and 404 and along the surface of storage portion 102 and may meet at approximately substantially vertical bisecting line 406 , as indicated by dotted lines in fig4 . in other examples , primary straps 114 and 118 end at connection areas 116 and 404 or extend a different length and / or geometry along storage portion 102 . primary left shoulder strap 114 , primary right shoulder strap 118 , and substantially horizontal line 408 are all tangential to a first circle 410 having a radius 412 of approximately between 8 and 12 centimeters . first circle 410 is substantially parallel to vertical plane 302 shown in fig3 . in one example , radius 412 measures approximately 10 centimeters . primary left shoulder strap 114 and primary right shoulder strap 118 curve away from substantially vertical bisecting line 406 at between approximately one - third to two - thirds of the length of each strap , the curve being substantially equal to the curve of an arc 414 of a second circle 416 having a radius 418 of approximately between 7 and 11 centimeters . arc 414 measures approximately between 25 and 45 degrees . in one example , radius 418 measures approximately 9 . 5 cm . in another example , arc 414 measures approximately 36 degrees . as used herein , an arc measurement of a certain number of degrees is defined by the angle whose sides are extended until the circumference of the circle is intersected . for example , when a 36 - degree angle &# 39 ; s sides are extended to the circumference of a circle from the center , the portion of the circumference between the extended sides is a 36 - degree arc . fig4 shows primary shoulder straps 114 and 118 as having the same amount of curve . in other examples , the curve could vary slightly to account for an individual &# 39 ; s physique . primary shoulder straps 114 and 118 may be of varying width . a range of desirable widths is shown in fig4 , with the white areas representing the minimum desired width of each strap and the gray areas representing the maximum desired extent for optimal comfort . as illustrated , the width of each strap may vary within the range of approximately 2 centimeters and approximately 12 centimeters . as noted in some examples below , however , variation to greater and / or lesser widths do not depart from the scope of the present invention . in one example , at the area where the straps attach to storage portion 102 , the minimum desired width of each strap is approximately 3 centimeters , and the maximum desired width is approximately 8 centimeters . in another example , at the second ends of the primary shoulder straps where the primary straps connect to the secondary straps , the minimum desired width of each strap is approximately 1 centimeter , and the maximum desired width is approximately 5 centimeters . in a further example , at the area where the straps attach to storage portion 102 , the minimum desired width of each strap is approximately 4 . 125 ( 4 and ⅛ ) centimeters , and the maximum desired width is approximately 4 . 75 ( 4 and ¾ ) centimeters . in still a further example , at the second ends of the primary shoulder straps where the primary straps connect to the secondary straps , the minimum desired width of each strap is approximately 1 . 375 ( 1 and ⅜ ) centimeters , and the maximum desired width is approximately 3 . 5 ( 3 and ½ ) centimeters . the specific strap width selected can vary depending upon the activity for which backpack 100 is designed , anticipated size of the user , mobility concerns , anticipated clothing that will be worn under the backpack , and other considerations . as shown in fig4 , the minimum desired strap width tapers from widest at connection areas 116 and 404 to narrowest where primary shoulder straps 114 and 118 connect to secondary shoulder straps 120 and 126 . although not shown in the figures , a sternum strap and / or waist strap may be included in backpack 100 . in examples including a sternum strap , the sternum strap may attach to primary shoulder straps 114 and 118 from approximately where primary shoulder straps 114 and 118 begin to curve to second ends 124 and 130 of primary shoulder straps 114 and 118 . the maximum desired extent 420 of bottom side 106 of storage portion 102 is approximately 55 centimeters in the vertical direction from substantially horizontal line 408 . in one example , maximum desired extent 420 is approximately 50 centimeters . the first ends 122 and 128 of secondary shoulder straps 120 and 126 attach to storage portion 102 at a minimum desired vertical distance 422 of approximately 35 centimeters from substantially horizontal line 408 . in one example , minimum desired vertical distance 422 is approximately 39 centimeters . in another example , minimum desired vertical distance 422 is approximately 38 . 8 centimeters . it is appreciated that approximately 38 . 8 centimeters can be considered to be approximately 39 centimeters . the vertical distance 424 between substantially horizontal line 408 and both the midpoint of second end 124 of primary left shoulder strap 114 and the midpoint of second end 130 of primary right shoulder strap 118 is approximately between 20 and 35 centimeters . in one example , vertical distance 424 measures 28 centimeters . the horizontal distance 426 between the midpoint of second end 124 of primary left shoulder strap 114 and the midpoint of second end 130 of primary right shoulder strap 118 is approximately between 65 and 85 centimeters . in one example , horizontal distance 426 is approximately 75 centimeters . fig5 illustrates in detail the attachment of first end 128 of secondary right shoulder strap 126 to storage portion 102 . strap 126 attaches to storage portion 102 such that when strap 126 is extended toward top side 104 , strap 126 forms an angle having a desired range of approximately between 0 and 45 degrees , measured down ( and to the left ) from vertical . in some examples , the desired maximum of this angle is between 15 and 30 degrees . in other examples , the desired minimum of this angle is between 0 and 10 degrees . combinations of desired minimum angles between 0 and 10 and desired maximum angles between 15 and 30 are also contemplated . in one specific example , the desired minimum angle is approximately 5 degrees , and the desired maximum angle is approximately 20 degrees . in another specific example , the desired minimum angle is approximately 10 degrees , and the desired maximum angle is approximately 15 degrees . when first end 128 is substantially perpendicular to sides 502 and 504 of secondary right shoulder strap 126 such that strap 126 appears rectangular , the attachment angle 506 of first end 128 to storage portion 102 corresponds to the angle of strap 126 from vertical . that is , attachment angle 506 is between 0 and 45 degrees measured up ( and left ) from horizontal line 508 and the angle of strap 126 measured down ( and left ) from vertical is also between 0 and 45 degrees . dashed lines 510 and 512 indicate the desired angle range of sides 502 and 504 of strap 126 when sides 502 and 504 are substantially parallel , first end 128 is connected to storage portion 102 , and strap 126 is extended toward the top side 104 from first end 128 . dashed line 510 indicates the maximum desired angle of sides 502 and 504 , which , when first end 128 is perpendicular to sides 502 and 504 , occurs when angle 506 is at the maximum desired . that is , when connection angle 506 is at the maximum desired , sides 502 and 504 are substantially parallel to dashed line 510 . similarly , dashed line 512 indicates the minimum desired angle of sides 502 and 504 , which , when first end 128 is perpendicular to sides 502 and 504 , occurs when angle 506 is at the minimum desired angle of 0 , resulting in sides 502 and 504 being substantially vertical . in some examples , dashed line 510 is at an angle of approximately 45 degrees measured down ( and to the left ) from vertical . in other examples , dashed line 510 is at an angle of between approximately 10 and 30 degrees measured down from vertical . in still a further example , dashed line 510 is at angle of approximately 20 degrees measured down from vertical . dashed line 512 is substantially vertical . in other examples , dashed line 512 is at an angle of between approximately 0 and 10 degrees measured down ( and to the left ) from vertical . in other examples , first end 128 is not perpendicular to sides 502 and 504 , and first end 128 is attached at an angle selected to cause sides 502 and 504 to have an angle between dashed lines 510 and dashed lines 512 , as described above . it should be appreciated that fig5 illustrates strap 126 attached such that sides 502 and 504 of strap 126 have an angle measured down and to the left of vertical between the angles represented by dashed lines 510 and 512 . solid lines 514 and 516 , along with dashed lines 510 and 512 represent an approximate area of storage portion 102 on which it is desirable to attach first end 128 . as discussed above , minimum desired vertical distance 422 in fig4 indicates the minimum desired vertical distance between substantially horizontal line 408 of fig4 and the midpoint of first end 128 when attached to storage portion 102 . in some examples , the attachment illustrated in fig5 is mirrored for secondary left shoulder strap 120 . fig6 illustrates ergonomic backpack with enhanced fit 600 that has a “ yoke ” strap configuration . backpack 600 is substantially similar to backpack 100 of fig1 - 5 except for the connection of the primary shoulder straps to the storage portion . primary left shoulder strap 614 attaches to storage portion 602 along first connection area 620 , and primary right shoulder strap 618 connects to storage portion 602 along first connection area 622 . in fig4 , the primary straps were shown as being tangential , along with a substantially horizontal line , to a circle . in the example shown in fig6 , the area between the points along primary shoulder straps 614 and 618 that first touch circle 624 is filled in with material to form a yoke connection . primary left shoulder strap 614 and primary right shoulder strap 618 are connected to each other and to storage portion 602 adjacent to first and second connection areas 620 and 622 with one or more pieces of material such that the one or more pieces of material form a curve between primary left shoulder strap 614 and primary right shoulder strap 618 substantially the same as the curve of circle 624 . many backpacks , such as the backpacks illustrated in fig1 - 6 , are designed to be “ unisex ” and fit both men and women . women often still prefer backpacks designed especially for the female physique . fig7 and 8 illustrate ergonomic backpacks with enhanced fit similar to the backpacks shown in fig4 and 6 but that are specifically designed for women . fig7 illustrates an ergonomic backpack with enhanced fit 700 . as with backpack 100 of fig1 - 6 , backpack 700 includes primary left shoulder strap 702 , primary right shoulder strap 704 , storage portion 706 , and secondary shoulder straps 708 and 710 . in contrast to circle 410 of fig4 , the circle 712 tangential to primary left shoulder strap 702 , primary right shoulder strap 704 , and substantially horizontal line 714 has a smaller radius 716 of between approximately 5 and 10 centimeters . in one example , radius 716 measures approximately 7 . 5 centimeters . the vertical distance 718 between substantially horizontal line 714 and both the midpoint of second end 720 of primary left shoulder strap 702 and the midpoint of second end 722 of primary right shoulder strap 704 is approximately between 20 and 35 centimeters . in one example , vertical distance 718 measures approximately 28 centimeters . in another example , vertical distance 718 measures approximately 27 . 3 centimeters . the horizontal distance 724 between the midpoint of second end 720 of primary left shoulder strap 702 and the midpoint of second end 722 of primary right shoulder strap 704 is approximately between 65 and 85 centimeters . in one example , horizontal distance 724 is approximately 75 centimeters . in another example , horizontal distance 724 is approximately 75 . 1 centimeters . backpack 700 also differs from backpack 100 in the amount of curvature of primary shoulder straps 702 and 704 as represented by circle 726 . arc 728 of circle 726 is between approximately 35 and 55 degrees . in one example , arc 728 measures approximately 45 degrees . radius 730 is approximately between 7 and 11 centimeters . in one example , radius 7 30 measures approximately 9 . 5 centimeters . other dimensions , such as the maximum extent of storage portion 706 relative to substantially horizontal line 714 , may be the same as for backpack 100 or may be smaller to account for the smaller size of the average woman relative to the average man . fig8 illustrates an ergonomic backpack 800 with enhanced fit having a yoke connection between primary left shoulder strap 802 , primary right shoulder strap 804 , and storage portion 806 , similar to that discussed with regard to claim 6 . the present invention has been described in relation to particular examples , which are intended in all respects to be illustrative rather than restrictive . alternative examples will become apparent to those of ordinary skill in the art to which the present invention pertains without departing from its scope . from the foregoing , it will be seen that this invention is one well adapted to attain all the ends and objects set forth above , together with other advantages which are obvious and inherent to the system and method . it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations . this is contemplated by and is within the scope of the claims .
an ergonomic backpack with an enhanced fit is provided . the backpack comprises a storage portion , primary left and right shoulder straps , and secondary left and right shoulder straps . the primary shoulder straps connect to the secondary shoulder straps to allow a user to wear the backpack over her shoulders . the dimensions and arrangement of the storage portion and primary and secondary shoulder straps are selected to optimize fit and comfort .