Abstract:
Footwear for a human foot containing an elongated sole piece having a front, middle and rear section and having a ground engaging bottom surface and an upper surface in which the wearer&#39;s foot is received and, an upper piece secured to said sole piece, said upper piece providing an enclosed embracing foot enclosure having a counter section at the rear of the foot, a mid-body section, and a toe box section at the front, wherein said sole piece has a curved sole at the rear section of the sole to permit the user&#39;s foot to be tilted forward to enhance the power of the push when the user&#39;s foot makes contact with ground when the user strikes at the user&#39;s heel. In addition, the shoe can have an improved tread design and a removable and replaceable shock absorbing insert. The shoe preferably employs the principle of energy conversion.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of Ser. No. 08/719,685 filed Sep. 26, 1996, and incorporates Ser. No. 08/719,685 U.S. Pat. No. 5,875,568 by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention describes an imaginative new footwear design based on the principle of energy conversion. The inventive footwear will make walking and running smoother, easier, more efficient, quicker, and simultaneously will reduce injuries arising from impact forces. 
     All walkers and runners fit in two simple categories, those who land on their heels and those who land on their toes. Although the term “runner” is used throughout the specification, it is noted that the term “runner” could also be a person walking and not running (“walker”). 
     Heel runners: These, known also as “heel strikers”, land on the back portion of their heel, roll forward on the outer side of the foot, and push off from the toe-forefoot area. The “striking” occurs in a relatively small region at the rear and outside of the heel. The impact of force or pressure of landing is calculated in pounds per square inch. That is, the weight of the runner multiplied by the impact area in square inches (small; say one half by one inch). The resulting impact pressure or force is large, often awesome. Since the descent of the foot on hitting the ground stops abruptly, in fact almost instantaneously, the law of “equal opposite forces” dictates that an equal pressure or force is transmitted in the opposite direction, back up the leg from foot to ankle to knee to hip. Taken over time, this jolt in distance runners (30 miles or more a week) causes predictable wear and tear problems involving foot, ankle, knee, hip and even back. This is the source of most injuries in distance runners. In addition, most “heel strikers” land with center of gravity slightly behind the point of impact, hence some of the reactive force up the leg actually pushes them backward. The runner locks the knee and “pogo-sticks” over the foot before rolling forward to the push-off position. This is inefficient, wasteful of energy, and tiring while causing a small though real slowing of the runner&#39;s forward progress. 
     Toe Runners: The other, smaller group of runners land on their toes or actually their forefoot areas. The point of impact is more apt to be under or modestly behind their center of gravity. The knee is slightly bent and absorbs some reactive energy. This style propels the runner forward, is more efficient, less tiring, and less prone to injuries. This group tends to be the sprinters and the elite distance runners. 
     All shoes are basically the same. Tops to cover the foot and keep the bottoms in place. Bottoms to protect the sole and to provide cushioning to absorb impact pressures. 
     Over recent years, shoe manufacturers have developed a variety of materials to reduce impact pressures through principles of compression and dispersion to absorb energy. Thus, modifications in design and composition of the heels (sponges, inserts, treads, air, and gels) and forefoot (sponges, inserts, and treads). All shoes employ the same principles with only a variation in theme. Thus the following: 
     U.S. Pat. No. 4,616,335 describes an athletic shoe structure including shock absorbing portions in the heel and foot areas of the sole of the shoe as well as particular placement of flexible nubs on the soft area. 
     U.S. Pat. No. 4,348,821 is directed towards the development of a shoe sole construction that will be mechanically effective for walking, running or jogging. 
     U.S. Pat. No. 4,262,435 is directed to an improved athletic shoe and with the sole piece as a wedge to facilitate supporting the runner&#39;s foot when contacting the ground. 
     U.S. Pat. No. 4,614,046 issued to Dassler (“Dassler”) describes a shoe which has two low points and not a single low point (FIG. 5 of Dassler). One low point is in the middle to the front of the shoe and the other low point is in the middle to the back of the shoe. There is not a single low point as is preferred by one of the embodiments the inventive shoe. Therefore, the shoe of Dassler would not roll smoothly forward converting energy into useful forward motion while reducing reactive impact force that normally travels back to the leg. There is no suggestion nor teaching in Dassler to have a single low point which would enable the runner to convert this negative energy into positive energy. 
     U.S. Pat. No. 4,372,059 issued to Ambrose (“Ambrose”) discloses a shoe with a single low point (at the line 4—4) in about the center of the sole. The problem that arises with this location of the single low point is that when the heel striker&#39;s shoe makes contact with the ground surface at the back end of the shoe, the shoe will try to roll forward, but in reality, will apply a force that may either cause the shoe to roll backwards or cause the user to force the shoe to roll forward being less efficient and generally increasing the possibility of injury to the user. One embodiment of the inventive shoe would provide that when the user lands on the ground surface on the back rear section of the sole of said shoe, the sole would then roll from the rear section to the front section of the shoe smoothly, thereby reducing reactive impact force. 
     Today, there is a need to make the shoe better by incorporating the concept of “conversion” in the design of the shoe. There is no shoe to date that employs the principle of energy conversion. 
     SUMMARY OF DESIGN CONCEPT 
     This invention focuses on energy conversion as a new concept in running shoes. Secondarily it describes a new configuration for the treads and a new, replaceable shock absorber unit. Both are a direct consequence of the basic innovated shoe design. 
     SUMMARY OF THE INVENTION 
     An object of this invention is the design and development of the shoe with a rounded heel strike area and gently curved bottom. The user, such as a walker or runner, while engaging in movement would have the shoe make contact with the ground surface and the shoe would roll smoothly forward converting energy in a useful forward motion while reducing the reactive impact force that normally travels back up the leg. The runner would thus be more efficient with simultaneous decrease in injuries due to impact pressures. 
     The term shoe is used throughout the specification and in some figures specific shoes are mentioned. However, it is to be understood that the term “shoe” includes running shoes, walking shoes, slippers, sandals, thongs and boots. 
     Another object of this invention is the design and development of modified treads. Since most heel strikers slide or shuffle rather than plant their foot in making first contact to the ground, the treads on the heel and back portion of the shoe should embrace or utilize this fact by making the treads a series of longitudinal grooves much like the grooving of an automobile or airplane tire. In contrast, the forefoot treads should be horizontal grooves or ridges to facilitate the force or gripping of the ground in the push-off of running. 
     Another object of this invention is the design development of the replaceable shock absorber unit to nestle within the rounded, thickened heel. 
     Another object of this invention is the design of the shoe that will enable a heel striker to land on the rear section of the sole behind the ankle. When the runner is walking or running, the runner&#39;s shoe would land in front of the runner&#39;s center of gravity. The sole of the shoe could have a single low point located backwardly of the ankle. When the shoe is resting on a horizontal flat ground surface the front of the shoe can be elevated such that the inner sole would be parallel to the ground surface. 
     Taking these three components separately and together, this invention will create a shoe to enhance ease, comfort, smoothness, and efficiency while allowing a greater longevity of the product and reducing running injuries. 
     This invention is directed to a shoe for a human foot comprising a sole piece and an upper piece. The sole piece consists essentially of a front, middle, and rear section with a ground engaging bottom surface. Further, the sole piece will be curved, particularly at the rear permitting the users foot to tilt slightly forward to enhance power during the push-off phase of the stride. The upper piece, secured to the bottom, creates an enclosure to embrace the foot. The upper piece can partially or fully enclose the shoe. If the upper piece fully encloses the shoe it too would have a front or toe box section, a middle and a rear section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a side elevational view of an embodiment according to this invention; 
     FIG. 2 shows a bottom plan view of the running shoe shown in FIG. 1, showing a sole tread design according to this invention; 
     FIG. 3 shows a side elevational view of an alternate compression insert design according to this invention; 
     FIG. 4 shows a schematic view showing the running shoe contacting the ground surface with the user&#39;s leg as a point of reference; 
     FIG. 5 shows a back elevational view of the running shoe, shown in FIG. 1, showing an alternative insert located partially through the sole instead of completely through the sole according to this invention and 
     FIG. 6 shows a side elevational view of another shoe according to this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a side elevational view of a running shoe according to this invention. The running shoe  10  has a sole  12  which would make contact with the ground surface  19 . The running shoe  10  has an upper portion  14  that is connected to the sole  12 . The sole  12  would have a rounded heel  16  at the rear section of the sole  12  and a toe  18  at the front of the sole  12 . The rounded heel  16  would enable a heel-striker to hit on the heel  16  and roll forward on the surface  19  and be able to push-off at the toe  18 . The sole  12  of the shoe  10  could have a single low point located at the ankle or backwardly of the ankle on the bottom and back portion of the sole  12 . This single low point would be located at the heel  16  of the shoe  10 . When the shoe  10  is resting on a horizontal flat ground surface, the inner portion of the shoe  10 , in particular, the top of the sole  12  would not be parallel to the ground surface, but would be higher in elevation in the back at the location of the heel  16  and lower in elevation at the front at the location at the toe portion  18 . The bottom of the sole  12  would make contact to the ground surface when in use. The top of the sole  12  would be inside the shoe and would not make ground contact but would be in close proximity to the users foot. When viewing the top of the sole  12  (inner sole  12 ) from the rear of the shoe  10 , the inner sole  12  would therefore be angled downward. The runner would have the runner&#39;s toes facing to the ground surface while wearing the shoe  10  and not be parallel to the ground surface. On a conventional shoe, the toes of the runner would be parallel to the ground surface and not point towards the ground surface Another words, while the inventive shoe  10  is resting on a flat ground surface, the front of the shoe  10  can be elevated while keeping the heel  16  on the ground surface  19  such that the top of the sole can adjusted to be parallel to the ground surface. 
     Also it is possible to have a shock-absorbing insert  20  that can be located in the in rear of the sole  12  or above the sole  12  in the rear of the running shoe  10 . The insert  20  can be partially through the sole  12  (as shown in FIGS. 1,  2  and  5 ), such as at least about 50% and preferably at least about 75% and have locking mechanism that enables a user to push the insert  20  into the shoe  10  and the insert  20  would lock into position and would not come out of the shoe when in use. The insert  20  alternatively could go completely through the shoe  10  (being exposed transversely on each side of the running shoe  10 ). The insert&#39;s  20  purpose is to provide a compression device for the running shoe  10 . There are a n umber of types of possible inserts  20  that could be used. The insert  20  can have a core  22  in the center. The core  22  can be made of an shock-absorbing material such as, but not limited to a rubber, a rigid foam or a plastic material. The core  22  can be the length of the entire insert  20 . Connected to the core  22  can be radial ribs  25 . The radial ribs  25  can be made of the same or different material as the core  22 . Each radial rib  25  can have one end connected to a casing  28  and can have the other end connected to the core  22 . 
     It is also possible to have a tab  24  connected to the insert  20 . An index arrow  26  can be located on the sole  12 . Having the tab  24  and the index arrow  26  would make it easier to determine how much the insert  20  is rotated. The user can rotate the insert  20  in increments of about 15° about 180°, preferably from about 15° about 30°, every time the user laces up the shoes. The index arrow  26  will help the user to measure how much the user has rotated the insert  20 . For convenience, the running shoe  10  can have marks  21  on the sole  12  or above the sole in the rear of the running shoe  10  such that the marks  21  are located around the outer circumference of the insert  20 . 
     FIG. 2 shows the bottom plan view of the running shoe  10  shown in FIG. 1, showing a sole and tread design. The rear tread  30  would be longitudinally to accommodate the shuffler (a runner who shuffles his feet on the ground instead of picking his feet off the ground) and to maximize the energy of the shoe when it hits the ground surface  19  instead of resisting the shoe  10  when the shoe  10  rolls on the ground surface  19 . In sharp contrast, the forefoot treads  32  should be transverse allowing the treads  32  to grip the road surface at the moment of push-off. The forefront treads  32  would be perpendicular to the longitudinal rear threads  30 . 
     FIG. 3 shows a side elevational view of an alternative compression tube insert design. The insert  40  can be removable and replaceable. The insert  40  can be made up of longitudinal hexagonal cells  42 . The cells  42  would connect and fit inside a casing  44 . There could be an outer flange  46  covering the casing  44 . Optionally, there could be a core  48  as is shown in FIG. 3 in phantom. The hexagonal cells  42  can be connected on top of the core  48  and inside the casing  44 . If no core  48  is present, then the hexagonal cells  42  can fit one next to the other inside the casing  44 . There could be a tab  50  connected to the outer flange  46 . Additionally, there could be an index marker  52  located on the rotatable tab  50  to allow easy identification of how much the insert  40  has been rotated on the shoe  10 . 
     FIG. 4 shows the schematic side elevational view showing the running shoe contacting the ground surface with the user&#39;s leg as a point of reference. When the shoe  10  strikes the ground surface  19 , the outer back bottom of the heel  16  at the rear section  60  of the sole  12  makes contact with the ground surface  19 , with the foot simultaneously rolling forward to the toe  18 . The rear section of the sole  12  can be divided to a front portion  62  and the rear portion  60 . The single low point of the sole  12  would be located at the rear section  60  of the sole  12  (see the portion of FIG. 4 at the far right). The center portion of the FIG. 4 illustrates the shoe  10  rolling forward with the complete or almost complete surface of the sole  12  making contact with the ground surface  19 . The left view illustrates the runner then pushing off the toe  18  having a slightly bent knee. Since the knee is slightly bent, the impact energy is thus converted to forward energy or forward thrust, propelling the runner along his way. The design of the shoes, in particular, having an enlarged rounded or curved raised heel portion causes this phenomenon to occur. FIG. 4 illustrates the runner landing on the heel  16  of the shoe  10  being in front the runner&#39;s center of gravity  64  and the shoe  10  movement during the course of ground contact. 
     When the shoe  10  is resting on a level surface, the upper top sole  12  where the foot would rest, would not be parallel to the ground surface like all athletic shoes, but would actually have the heel portion slightly higher in elevation than the toe portion of said inner sole. The back end of the heel on the sole could be curved. 
     FIG. 5 illustrates a rear elevational view of the insert  20  located in the rear of the sole  12 . The insert  20  is shown going partially through the sole  12 . There could be a locking mechanism  70  which would enable the user to insert the insert  20  and have the insert  20  lock into place. It is possible that the locking means  70  is the material of the sole  12 . Another way to have a locking means  70  is by having a radial groove  72  which is slightly larger in diameter than the diameter of the hole  74  and slightly larger in diameter than the insert  20 . The insert  20  could have a radial bead  73  at the end of the insert  20 . The diameter of the insert  20  at the bead  73  location would be larger than the diameter of the hole  74 . However, the diameter of the insert at the bead  73  would be slightly smaller than the diameter of the radial groove  72 . The insert can be forced into position by pushing the insert through the hole. There will be some resistance because the radial bead  73  is greater than the hole  74 . This way when the insert  20  would form a snug fit inside the radial bead  73 . The insert  20  can still be rotatable and removable. 
     FIG. 6 shows a side elevational view of another shoe according to this invention. The shoe can be a sandal, thong, slipper etc. The user&#39;s toes could also be covered although that it is not shown in FIG.  6 . The shoe  10 A has a sole  12  which would make contact with the ground surface. The shoe  14 A has an upper portion  14  that is connected to the sole  12 . The upper portion can be a strap if the shoe is a sandal or thong or partial enclosed material as shown in FIG. 6 if the shoe is a sandal or slipper. The sole  12  would have a rounded heel  16  at the rear section of the sole  12  and a toe  18  at the front of the sole  12 . The rounded heel  16  would enable a heel-striker to hit on the heel  16  and roll forward on the surface  19  and be able to push-off at the toe  18 . The sole  12  of the shoe  10  could have a single low point located at the ankle or backwardly of the ankle on the bottom and back portion of the sole  12 . This embodiment would be similar to the embodiment shown in the previous figures except that the upper portion  14  that is connected to the sole  12  does not completely enclose the sole  12 . 
     The shoe can be fully enclosed like the conventional running or walking shoe. The shoe can be partially enclosed like a sandal or slipper. The shoe can also be in the shape of a conventional thong and have a strap connected to the sole and would enable the user&#39;s foot to securely fit inside the strap and the sole. The strap could be located on the sole to fit between a user&#39;s big toe and second toe. The strap would also go on top of the user&#39;s foot to keep the thong secured to the user&#39;s foot. 
     Summary of the advantages of the shoe are as follows: 
     (1) The Rounded Heel Strike Area 
     As the heel makes contact with the ground surface, the foot instantaneously rolls forward. The impact energy is thus converted to forward energy or forward thrust, propelling the runner along his way. This is an energy saving device that simultaneously reduces the jolt directed back up the leg under the law of equal and opposite forces. This configuration would lessen discomforts and injuries while making the runner more efficient and faster. 
     (2) The Push-off 
     In both walking and running a person normally plants the heel, rolls forward on the outer portion of the foot, then pushes off with toes and fore foot. The push-off provides the drive or energy to propel the body forward. The new shoe with rounded and raised heel flows easily into gently sloping mid-foot and fore-foot. Inside the shoe, the foot itself is tilted ever so slightly forward enhancing the power of push off (similar to the sprinter running on his toes). 
     (3) The Treads 
     Most people are heel-strikers and shuffle making contact with the ground. The treads should be designed on the heel area to utilize this fact. The tread should be grooved longitudinally to accommodate the shuffler. They should not be configured into miscellaneous swoops and swirls which is so common in running shoes today. The treads should look like the major grooving in automobile and airplane tires. This visual analogy gains further strength in knowing the rounded heel is specifically designed to roll the foot forward. In sharp contrast, the fore foot treads should be transverse allowing the treads to grip the ground at the moment of push off. 
     (4) Cylindrical Shock Absorber 
     Running shoes wear out, treads erode, heels loose cushioning, and the fore foot goes flat. To prolong the life of the shoe, it is possible to have an insert replacement shock absorber within the heel. The insert can extend from side to side for the full width of the heel area. The insert can be constructed to allow rotation. The runner could rotate the insert about 15-20 degrees every time the runner puts on the shoes. This would eliminate repeated pounding on exactly the same spot; thereby, extending the life of the cushioning. The cushioning can also be constructed as removable. The runner can remove the insert, reverse it and reinsert it. When the cushioning or insert is worn out the runner would remove it and can than replace it with a fresh unit. 
     More cushioning could be added to the fore foot because of the greater thickness of the shoe. With this combination of techniques to moderate impact pressures (conversion, compression/absorption, and dispersion) the bottom surface could relinquish any responsibility as a shock adsorbate. Just make it thin and worldly tough such as using KEVLAR a trademarked product which is a high-strength aramid. 
     This inventive design of the shoe, deploys a conversion of energy, a new tread pattern, and a cylindrical cushioning unit that could be both rotated and replaced. Variations with these three concepts is endless. The rounded profile of the shoe could well vary to the height and stride length of the runner, with flat versus hilly country, with short versus long run/races, etc. Different tread configurations would surely emerge. It would also be possible for the insert to be a configuration of hexagonal shaped cells made up of compressible material such as the honeycombed shape constructed by bees. 
     The shoes are designed to redirect impact forces that slow progress and cause injuries. The principles involved would also be applicable to walking. Since the new shoe conserves energy it theoretically should be faster for longer races than sprints. 
     The inventive running shoe is helpful in reducing the assault of impact pressures on the body, by the conversion and dissipation of energy. 
     The shoe would have the feature that said bottom surface of said sole piece from said rear section to said front section has a single low point located on a smooth continuous surface at the heel of said rear section of said sole piece to assure elevation of the heel, whereby when said shoe is worn by a user said sole at said rear section at the back end of said rounded sole piece makes initial contact with a ground surface, at a contact point at the rear end of said sole piece and the contact point of said sole piece rolls in a smooth continuous motion to said front section thereby reducing the reactive impact force. This feature would permit the user to change the user&#39;s style of running by converting the negative energy (force going back into the runner&#39;s legs upon ground contact) into positive energy thereby propelling the runner forward and eliminating most or all of the force going back into the runner&#39;s leg. The shoe is most effective for a heel striker since the heel striker lands on the heel of the shoe and the shoe permits the heel striker to roll the heel forward and thereby creating positive energy. 
     While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described.