Abstract:
A method of manufacturing an article of foot apparel that includes a platform curved to anticipate the natural movement of a foot. The method includes forming the platform with a heel pad having a geometric center point. The method also includes connecting a retaining covering to the platform that is configured to retain a foot at the front of the platform and to allow the heel of the foot to move freely relative to the heel pad. The article of foot apparel conforms more closely to the actual physiology of the foot and allows the heel of the foot to remain centered in the heel pad when worn.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a divisional application of U.S. patent application Ser. No. 11/609,800, filed Dec. 12, 2006, now U.S. Pat. No. 7,552,546 which claims the benefit of U.S. Provisional Patent Application No. 60/749,894, filed Dec. 13, 2005. These applications are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to footwear and more particularly relates to open-heeled foot apparel. 
   2. Description of the Related Art 
   Open-heeled or backless footwear such as sandals, flip-flops, clogs, or the like are a popular clothing item worn by people of all ages in many areas around the world. Though popular as footwear, open-heeled foot apparel often causes discomfort to the wearer because the heel pad of the foot-receiving platform typically does not line up accurately with the actual contact area of the heel. Particularly when the foot is raised, such as when walking, the foot-receiving platform tends to swing toward the outer edge of the foot. As the foot comes down on the foot-receiving platform, the heel tends to contact the platform near the inner edge, which provides minimal support to the foot and often creates a worn heel-contact area off-centered from the available heel pad. 
     FIGS. 1A-1B  illustrate one embodiment of a flip-flop  100  similar to those currently available on the market. Flip-flops  100  typically are a backless sandal held to the foot by a thong between the big toe and the second toe. The flip-flop  100  commonly comprises a platform  110 , a heel pad  112 , and a retaining covering  114  such as straps  114 . 
   In certain embodiments, the platform  110  is made of a flat foam rubber with straps  114  attached at three contact points  116  and is generally shaped to contour the foot. Alternatively, flip-flops  100  and/or open-heeled foot apparel may be made from a variety of materials such as leather, wood, plastic, elastomer and the like. Some backless sandals even include a spiked heel and/or an inclined platform  110 . The retaining covering  114  may comprise a single strap  114  or an intricate infrastructure. Those of skill in the art will recognize that flip-flops  100  and other backless footwear may be configured from a variety of materials. In addition, the platform  110 , heel pad  112 , and retaining covering  114  may be configured in a variety of styles and/or arrangements. 
   The retaining covering  114  may facilitate defining a centerline  118  that divides the area within the retaining covering  114  approximately equally. In the depicted embodiment, the centerline  118  passes through an approximate center of the platform  110  beginning from a midpoint  120  located between contact points  116   b  and  116   c.    
   The heel pad  112  may include the lower portion of the platform  110 . A geometric center point  122  may be identified for the heel pad  112 . A line  124  passing through the center point  122  and the midpoint  120  may facilitate defining an angle  126 . In certain embodiments, the angle  126  may represent the natural curve in the foot. Generally, the angle  126  may be insubstantial and may be about 180 degrees. 
     FIG. 1B  illustrates an actual heel contact area  128  that has a center point  129 . The heel contact area  128  is typically located near the inner edge  130  of the flip-flop  100 . As the platform  110  swings during movement, the heel makes contact near the edge  130  of the platform  110 , which offers a diminished amount of support to the heel. The inner edge  130  tends to break down quicker than the outer edge  132 , creating an uneven, sloped platform  110 . The user typically experiences discomfort as the heel pad  112  wears unevenly. In addition, the outer edge  132  of the flip-flop  100  typically boasts an excess of unused platform material. The excess material may annoy the user. 
   In shoes or footwear that have a heel retaining device or back, the problem is somewhat mitigated. In such an embodiment, the platform  110  and/or sole of the shoe is generally bound to the foot and does not typically swing, as is common with open-heeled footwear. As a result, the foot-receiving platform  110  generally remains in line with the foot, particularly the heel. Yet the demand for open-heeled footwear continues to remain high. 
   From the foregoing discussion, it should be apparent that a need exists for an open-heeled article of foot apparel that anticipates the swinging movement of the foot-receiving platform and positions the center of the heel pad where the heel of the foot is most likely to strike. Beneficially, such an article of foot apparel would provide popular open-heeled footwear that is comfortable to wear and is long-lasting. Providing a heel pad centered where the heel of the foot is most likely to strike would provide better heel support to the user and would potentially increase the life of the foot apparel. 
   SUMMARY OF THE INVENTION 
   The present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available open-heeled footwear. Accordingly, the present invention has been developed to provide an article of foot apparel that overcomes many or all of the above-discussed shortcomings in the art. 
   The apparatus, in one embodiment, is configured to provide a curved platform for receiving a foot that anticipates the natural movement of the foot and comprises a heel pad having a geometric center point. The apparatus further comprises a retaining covering connected to the platform that retains a foot at the front of the platform and allows the heel of the foot to move freely. The retaining covering has a center line wherein a substantial angle is created at the point of intersection of a line passing through the geometric center point of the heel pad and the center line of the retaining covering. In certain embodiments, the substantial angle is more severe than the natural curve of the foot. 
   A method of the present invention is also presented for manufacturing an article of foot apparel. In one embodiment, the method includes providing a platform and a retaining covering having a centerline connected to the platform. The method also includes determining a heel contact area and aligning a heel pad to a center point of a heel contact area wherein a substantial angle is created at the point of intersection of a line passing through the geometric center point of the heel pad and the center line. 
   Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment. 
   Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention. 
   These features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
       FIG. 1A  is a plan view illustrating one embodiment of a typical flip-flop with a centralized heel pad; 
       FIG. 1B  is a plan view illustrating one embodiment of a typical flip-flop with an offset heel contact area; 
       FIG. 2A  is a plan view illustrating one embodiment of a flip-flop in accordance with the present invention; 
       FIG. 2B  is a plan view illustrating one embodiment of a flip-flop in accordance with the present invention relative to the flip-flop illustrated in  FIGS. 1A-1B ; 
       FIG. 3  is a plan view illustrating one embodiment of a sandal in accordance with the present invention; 
       FIG. 4  is a plan view illustrating another embodiment of a sandal in accordance with the present invention; and 
       FIG. 5  is a schematic flow chart diagram illustrating one embodiment of a method for providing open-heeled foot apparel with improved support in accordance with the present invention. 
       FIG. 6  is a plan view illustrating one embodiment of the sandal in accordance with the present invention; 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. 
   Furthermore, the described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
     FIG. 2A  depicts one embodiment of a flip-flop  200  in accordance with the present invention. The flip-flop  200  is similar to the flip-flop  100  illustrated in  FIGS. 1A-1B ; however, a platform  210  includes a heel pad  212  angled to provide improved support to the heel of the wearer. In certain embodiments, the platform  210  is curved to anticipate the natural curvature and movement of the foot. 
   The curved platform  210 , according to one embodiment, positions the heel pad  212  relative to the predicted heel contact area  128 . In certain embodiments, the center point  129  of the heel contact area  128  comprises the approximate geometric center point of the heel pad  212 . Aligning the heel pad  212  with the heel contact area  128  enables the heel to have substantial support on all sides. In addition, the heel pad  212  wears more evenly as the inner edge  130  receives about equal wear as the outer edge  132 . Accordingly, the heel contact area  128  wears longer than with a traditional heel pad  112 . 
   As mentioned, the traditional heel pad  112  may be aligned with the natural curvature of the foot represented by angle  126  in  FIG. 1A . In theory, the heel pad  112  should provide centralized support to the heel. However, the movement and shape of the foot as well as the retaining covering  114  affect where the heel actually contacts the platform  110  and  210 . 
   In the depicted embodiments, the straps  114  exert uneven pressure on opposing sides of the foot. The inner strap  114   a  typically exerts less pressure on the foot than the outer strap  114   b  under certain conditions. In one embodiment, when the foot is pressed down against the platform  110  and generally aligned with the shape of the platform  110 , the outer strap  114   b  retains the foot by providing tension against the corresponding side of the foot. In contrast, the inner strap  114   a  under the same condition typically remains relatively loose. 
   When the wearer lifts her foot, however, the tension generally shifts from the outer strap  114   b  and becomes more balanced between the two straps  114   a  and  114   b , causing the heel pad  112  of the platform  110  to swing outward. As the wearer steps down again, the tension of both straps  114   a  and  114   b  cause the heel to contact the platform in an offset position at about where the heel contact area  128  is outlined with a dotted line in  FIG. 1B . Altering the configuration of the straps  114  would alter the tension on the foot, but the problem of outward movement and uneven wear on the heel pad  112  would remain. 
   Referring back to  FIG. 2A , rather than altering the straps  114 , the flip-flop in the depicted embodiment adjusts the heel pad  212  to mitigate the problem. As a result, the user experiences greater comfort and improved heel support. The heel pad  212  is aligned with the movement of the foot in conjunction with the flip-flop  200 . Uneven wear and related pains are minimized and extraneous platform material may be eliminated. 
   The intersection of the centerline  118  and a line  216  passing through the geometric center point  129  preferably creates a substantial angle  218 . The upper portion of the flip-flop  200  with the retaining covering  114  may function as described above. Yet the curved platform  210  provides additional support to the heel when the wearer steps down on the platform  210 . The curvature of the heel pad  212  prevents the outer edge  220  from swinging past the heel of the foot in certain embodiments. 
   The platform  210  and the heel pad  212  may or may not be a single unit. The heel pad  212  may be attached to the platform  210  in certain embodiments. In one embodiment, the heel pad  212  is personalized for the wearer and may be applied to an existing article of open-heeled footwear. The platform  210  may be altered to suit an individual wearer. In one embodiment, the superfluous platform material on the outer edge  132  may be removed and may be used to increase the support provided to the inner edge  130 , creating a substantial angle  218 . In another embodiment, additional material may be added to the inner edge  130  of an existing flip-flip  100  to increase the amount of support provided to the heel contact area  128 . 
   In the depicted embodiment, the heel pad  212  curves at about where the retaining covering  114  contacts the platform at holes  116   b  and  116   c . In certain embodiments, the curve or angle  218  is more severe than the natural curve of the foot illustrated in  FIG. 1A , which is commonly emulated in footwear. 
     FIG. 2B  illustrates the improved flip-flop  200  relative to the traditional flip-flop  100 . The angle  222  may represent the amount of alteration of the curve  218  from the natural curve  126  of the foot illustrated in  FIG. 1A . In certain embodiments, the curve  218  may be more severe than the natural curve of the foot by greater than 20 degrees with a preferred difference of about 30 degrees. 
     FIG. 3  illustrates an alternative embodiment of a backless sandal  300  with a platform  310  for receiving a foot, a heel pad  312 , a retaining covering  314 , contact points  316 , a centerline  318 , a midpoint  320 , and a geometric center point  322 , which may align with the center point  129  of the heel contact area  128  in certain embodiments. The retaining covering  314  and the contact points  316  may facilitate defining the centerline  318 , which approximately equally divides the area between the retaining covering  314 . 
   In addition, the contact points  316   a  and  316   b  may define the midpoint  320  in certain embodiments. Alternatively, the midpoint  320  may be located above or below the line  321  that passes through contact point  316   a  and  316   b . The midpoint  320  may be defined by the centerline  318  and the intersection point of line  324  in one embodiment. In the depicted embodiment, the line  324  passes through the geometric center point  322  and defines the approximate centerline of the heel pad  312 . The heel pad  312  may be positioned relative to the heel contact area  128  as discussed above. 
   In certain embodiments, the geometric center point  322  of the heel pad  312  and the center point  129  of the heel contact area may be encompassed within the heel contact area  128  and/or within a central area  326  of the heel pad  312  and are not necessarily directly aligned. Those of skill in the art will recognize a benefit of the invention without precise alignment of well-defined points, such as the referenced geometric points  322 ,  129 . Thus a projected central area  326  containing the geometric center point  322  and the heel contact center point  129  is within the scope of the invention. 
   The retaining covering  314  may comprise various shapes and forms as is known in the art. In the depicted embodiment, the retaining covering  314  comprises a single strap  314  connected to the platform  310 . The foot may slide and the platform  310  may shift as discussed above. A heel contact area  128  may be determined and the heel pad  312  may be adjusted to support the heel and to anticipate regular motion. 
     FIG. 4  illustrates an alternative embodiment of a backless sandal  400 . The sandal  400  as depicted includes a curved platform  410 , a heel pad  412 , a retaining covering  414 , contact points  416 , a centerline  418 , a midpoint  420 , and a geometric center point  422 . The retaining covering  414 , which comprises a toe strap  414   a  and an angled strap  414   b , has an approximate centerline  418  that intersects with line  424  at about the midpoint  420 , creating a substantial angle  426 . 
   The midpoint  420  may be relative to the main strap  414   b  extending between contact point  416   a  and  416   b  in certain embodiments. Alternatively, the midpoint  420  may be relative to the established centerline  418  and the platform  410 . The line  424 , in the depicted embodiment, defines a line passing through the determined midpoint  420  and the geometric center point  422  of the heel pad  412 . 
   The depicted style of sandal  400  benefits from substantially aligning the heel pad  412  with the heel contact area  128 . The geometric center point  422  of the heel pad  412  consequently is located at a substantial angle from the center line  418  of the retaining covering  414 . The angled heel pad  412  provides greater comfort and support to the user. 
   The schematic flow chart diagram that follows is generally set forth as a logical flow chart diagram. As such, the depicted order and labeled steps are indicative of one embodiment of the presented method. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Although various arrow types and line types may be employed in the flow chart diagrams, they are understood not to limit the scope of the corresponding method. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown. 
     FIG. 5  illustrates one embodiment of a method  500  for providing open-heeled footwear with improved heel support. The method  500  begins  502  and includes providing  504  an article of foot apparel having a platform and a retaining covering, determining  506  an actual heel contact area, and substantially aligning  508  the heel pad with the center of the heel contact area. Then the method  500  ends  510 . 
   In certain embodiments, an article of open-heeled foot apparel may be customized to suit a particular foot and/or walking pattern. The heel pad may be aligned such that a substantial angle is created at the point of intersection of a line passing through the geometric center point of the heel pad and the center line of the retaining covering. The platform may be curved to anticipate the natural movement of the foot relative to the article of foot apparel. 
   In certain embodiments, the heel pad may be attached to the platform in order to substantially align  508  the heel pad with the center point of a heel contact area. In another embodiment, a platform may be formed as a single unit with a heel pad substantially aligned  508  with a center point of a heel contact area. In one embodiment, a platform material may be attached to the platform to supplement the support of the existing heel pad. 
     FIG. 6  shows a further way of describing the curvature of the flip-flop  200  of the present invention. In this depiction, the intersection of the centerline  119  and the line  216  passing through the geometric center point  129  preferably creates a substantial angle  219 . In certain embodiments, the curve or angle  219  is more severe than the natural curve of the foot illustrated in  FIG. 1A , which is commonly emulated in footwear. In certain embodiments, the curve  219  may be more severe than the natural curve of the foot by greater than 20 degrees. In one embodiment, the angle  219  is about 30 degrees. 
   The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.