Abstract:
A sandal having an active, self-adjusting harness and method therefore typically used in the out-of-doors for rigorous activities includes rubber and synthetic materials and exhibits a lightweight robust, high-strength, flexible construction including an elongated sole for supporting a foot where the sole has a toe end and a heel end. A center toe strap is anchored in the toe end and includes a distal end fixedly connected to a front buckle. A rear strap is anchored in the heel end and has a first end and a second end extending above the sole. The first end and the second end of the rear strap are respectively connected to an inside rear buckle and an outside rear buckle. A self-adjusting harness comprised of a single strap is anchored in the toe end. The single strap includes an inside end and an outside end each extending above the sole. The inside end of the single strap is circuited through the front buckle and the inside rear buckle while the outside end of the single strap is circuited through the front buckle and the outside rear buckle. The inside end and the outside end are engaged to form a closure over-the-instep of the foot. Finally, an independent adjustable heel strap is attached to the outside rear buckle and the inside rear buckle. Subsequent movements of the foot result in continuous adjustments in the tension of the single strap for regulating and equalizing the tension in the harness.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to footwear. More specifically, the present invention relates to methods and apparatus for a sandal having an active self-adjusting harness which cooperates with a center toe strap and an independent adjustable heel strap to provide for continuous adjustment for securely affixing the sandal to a human foot during physical activity. 
     2. Description of the Prior Art 
     The prior art is directed to methods and apparatus for sandal type footwear used during physical activities. Sandals are one of the first types of footwear known to mankind and continue to be popular. Early sandals included a flat component formed of a suitable material such as leather that served as a sole. The flat sole was placed under the foot to provide protection against the ground surface. Various methods to attach the sandal to the foot are also known. Some attachment examples include the use of a suitable material such as leather to attach the sole of the sandal to the toes or ankle of the foot. 
     In more recent times, a vamp which covers the instep of the foot was employed to provide a slide type sandal. The vamp only partially covered the top of the foot so that the toes might extend outward into the open air. In the alternative, the vamp may cover most of the top of the foot or even enclose the entire forward portion of the foot. Leather laces could be employed to improve the attachment of the slide type sandal to the foot by lashing the sole and/or the vamp of the sandal to the foot. However, neither of these types of means for attaching the sandal to the foot were satisfactory during rigorous physical activity. 
     The rear heel strap was subsequently introduced which was attached to the vamp or other structural component of the sandal. The rear heel strap was used to wrap around the heel of the foot to ensure that the sandal remained attached to the foot. Sandals often incorporated buckles, hook and eyelet fasteners and other types of mechanical fasteners to adjust the tension in the rear heel strap. The greater the tension in the rear heel strap, the tighter the sandal was attached to the foot. This feature was an improvement in securing the sandal to the foot during leisure activities. However, the rear heel strap often became loose during rigorous activities such as competing in baseball, beach ball sports and running in the sand to name a few. Under these conditions, the rear heel strap would slip down around the heel of the foot resulting in the sandal falling off of the foot. 
     Thus, sandals were subsequently modified to improve the attachment mechanism to the human foot for use during physical activity. In a first example, a sandal is known having an elongated sole configured to the profile of a human footprint. The sandal has a toe end and a heel end and employs a toe strap connected at two anchor points to grip the forward part of the wearer&#39;s foot. A heel strap is connected at two anchor points to grip the ankle of the wearer&#39;s foot. A lateral strap is connected between the toe strap and the heel strap which is located on the outside of the sole and parallel to its surface so that it is operable to stabilize the other straps and to maintain essentially constant tension in the individual straps as the sole flexes. The toe and heel straps are infinitely adjustable so that the wearer can cinch the sandal to his foot by adjusting the straps in a manner that the sandal will not be dislodged during rigorous activity. 
     In another example, a sandal construction includes a convertible heel harness which is employed to minimize foot slippage in its closed rearward position. Likewise, the convertible heel harness becomes a part of a frontal ankle strap in its alternate, forward position. The sandal may be slipped into and worn with an open back, or may be placed upon the foot with the harness engaging the heel. 
     Thus, there is a need in the art for a sandal intended for use during rigorous physical activity that includes an insole and an active, self-adjusting harness connected thereto wherein the harness is comprised of a single continuous strap having a plurality of strap sections. The self-adjusting harness in combination with a center toe strap and an independent adjustable heel strap functions to retain the sandal securely to a human foot. The harness is active in nature in that it is continuously self-adjusting and requires only a single over-the-instep strap closure to attach the sandal to the foot. The greater the upward pressure applied on the sandal, the tighter the harness becomes about the foot. 
     SUMMARY OF THE INVENTION 
     Briefly, and in general terms, the present invention provides a new and improved sandal typically worn as footwear in the out-of-doors during the warm months of the year. The sandal might typically be used during rigorous activities such as running, hiking and river rafting. However, the sandal can be used indoors as well as at the beach or the swimming pool. The novel and non-obvious sandal exhibits a cushioned insole layer and midsole layer upon which a human foot rests. The insole layer is mounted over and bonded to the midsole layer. The midsole layer is mounted over and bonded to a durable robust outsole layer which contacts the ground surface. The traction necessary to participate in rigorous activities is provided by the tread pattern included on the bottom of the outsole layer. The components of the sandal are comprised of rubber and manmade synthetic rubber and plastic cushioning materials. Further, the sandal exhibits a lightweight robust, high-strength, flexible construction and is economical to manufacture. 
     The insole, midsole and outsole layers are formed in the shape of a human foot having a toe end and a heel end. A center toe strap is anchored to the midsole layer and thus is stationary. The stationary center toe strap is connected to a front buckle. Likewise, a rear strap is anchored to the midsole layer and is connected to a pair of rear buckles. Anchored in the midsole layer and positioned above the insole layer is an active, self-adjusting harness comprised of a single strap. The single strap is circuited through each of the buckles and terminates in an over-the-instep closure. The harness in combination with the center toe strap and an independent adjustable heel strap provide the means by which the sandal is attached to the foot. Attachment can be accomplished by a single adjustment of the over-the-instep closure. 
     The present invention is generally directed to a sandal typically used in the out-of-doors and comprised of rubber and synthetic materials for exhibiting a lightweight robust, high-strength, flexible construction. In its most fundamental embodiment, the sandal comprises a construction having an elongated sole for supporting a foot where the sole has a toe end and a heel end. A center toe strap is anchored in the toe end and includes a distal end fixedly connected to a front buckle. A rear strap is anchored in the heel end and has a first end and a second end extending above the sole. The first end and the second end of the rear strap are respectively connected to an inside rear buckle and an outside rear buckle. A self-adjusting harness comprised of a single strap is anchored in the toe end. The single strap includes an inside end and an outside end each extending above the sole. The inside end of the single strap is circuited through the front buckle and the inside rear buckle while the outside end of the single strap is circuited through the front buckle and the outside rear buckle. The inside end and the outside end are engaged to form a closure over-the-instep of the foot. Finally, an independent adjustable heel strap is attached to the outside rear buckle and the inside rear buckle. Subsequent movements of the foot result in continuous adjustments in the tension of the single strap for regulating and equalizing the tension in the harness. 
    
    
     These and other objects and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate the invention, by way of example. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a sandal having an active, self-adjusting harness of the present invention showing a self-adjusting, harness strap and an independent adjustable heel strap wrapped about a human foot shown in phantom. 
     FIG. 2 is a front elevational view of the sandal of FIG. 1 showing the self-adjusting harness, a center toe strap, and front inside and outside strap sections and an over-the-instep strap section of the harness strap. 
     FIG. 3 is a rear elevational view of the sandal of FIG. 1 showing the self-adjusting harness, over-the-instep strap section of the harness strap, a center toe strap, and the independent adjustable heel strap. 
     FIG. 4 is a right side elevational view of the sandal of FIG. 1 showing the self-adjusting harness, adjustable heel strap, a center toe strap, and front inside and outside strap sections, inside and outside lateral strap sections, and over-the-instep strap section of the harness strap. 
     FIG. 5 is a left side elevational view of the sandal of FIG. 1 showing the self-adjusting harness, center toe strap, adjustable heel strap, and front inside and outside strap sections, inside and outside lateral strap sections, and over-the-instep strap section of the harness strap. 
     FIG. 6 is a top planar view of the sandal of FIG. 1 showing the self-adjusting harness, center toe strap, adjustable heel strap, and front inside and outside strap sections, front inside and outside lateral strap sections, and over-the-instep strap section of the harness strap, all mounted upon an insole layer. 
     FIG. 7 is a bottom planar view of the sandal of FIG. 1 showing the rugged bottom surface of an outsole layer. 
     FIG. 8 is a top planar view of a midsole layer of the sandal of FIG. 1 showing a penetration and a pair of channels cut into the midsole layer for accommodating straps associated with the self-adjusting harness. 
     FIG. 9 is a bottom planar view of the midsole layer of the sandal of FIG. 1 showing straps positioned within the penetration a channels cut into the midsole layer. 
     FIG. 10 is a longitudinal cross-sectional view of the sandal of FIG. 1 taken along the line  10 — 10  of FIG.  6  and showing the insole, midsole and outsole layers, center toe strap, a rear inside strap section of a rear strap, and the front inside strap section of the harness strap. 
     FIG. 11 is a first transverse cross-sectional view of the sandal of FIG. 1 taken along line  11 — 11  of FIG.  6  and showing the center toe strap and the front inside and outside strap sections of the harness strap positioned within the forward channel of the midsole. 
     FIG. 12 is a second transverse cross-sectional view of the sandal of FIG. 1 taken along line  12 — 12  of FIG.  6  and showing the rear inside and outside strap sections of the rear strap. 
    
    
     DESCRIPTION OF THE INVENTION 
     The present invention is an article of footwear such as, for example, a sandal  100  having an active, self-adjusting harness  102  comprised of a single continuous strap having a plurality of strap sections. The self-adjusting harness  102  in combination with a center toe strap  104  and an independent adjustable heel strap  106  functions to retain an insole layer  108  of the sandal  100  to a human foot as is shown in FIG.  1 . 
     In addition to the plurality of straps mentioned in the previous paragraph which will be discussed in detail hereinbelow, the sandal  100  includes three layers of support for the foot. The three layers of support include the insole layer  108 , a midsole layer  110  and an outsole layer  112  best shown in FIGS. 10-12 but also shown in FIGS. 4-5. The insole layer  108  is the top layer upon which the foot rests as is shown in FIG.  1 . The outsole layer  112  includes a rugged, robust tread design  114  shown in FIG. 7 which makes contact with the ground surface. The midsole layer  110  is the middle layer positioned between the insole layer  108  and the outsole layer  112 . The three layers of support are vertically stacked and bonded together with a suitable bonding agent well known in the art of shoe and sandal construction. 
     The insole layer  108  is the top layer that supports the foot and thus must be cushioned. Consequently, the insole layer  108  can be fashioned from synthetic plastic rubber, neoprene, microcellular rubber, Ethylene Vinyl Acetate (EVA) or any equivalent material suitable for sustained cushioning of the foot. The bottom outsole layer  112  includes the rugged, robust tread design  114  and thus must be fashioned from a tough, rugged material. Therefore, materials that are suitable for use in forming the outsole layer  112  include rubber, synthetic rubber and Thermal Plastic Rubber (TPR). The midsole layer  110  which is positioned between the insole layer  108  and the outsole layer  112  also serves as a cushioning medium. As a result, the midsole layer  110  can be fashioned from the same materials that are use to fashion the insole layer  108 , i.e., synthetic plastic rubber, neoprene, microcellular rubber and EVA. 
     The three layers of support also include two other features that are shown in the drawing FIGS. and thus mentioned herein. A toe kick  116  is included in the design of the sandal  100  as is shown in FIGS. 2,  4 ,  5  and  10 . The toe kick  116  is the upward extending portion located at the front of the sandal  100 . The toe kick  116  is designed to keep the forward part of the foot from bumping external surfaces. Additionally, the toe kick  116  serves to make walking easier since the forward part of the foot is pointed in an upward direction prior to a step being taken. Additionally, a cup heel  118  is formed into the insole layer  108  of the sandal  100  as is shown in FIGS. 3-6 and  10 . The function of the cup heel  118  is to persuade the heel of the foot to the center area of the cushioned insole layer  108 . 
     In the sandal  100  of the present invention, the midsole layer  110  serves another function. Three of the straps used to secure the sandal  100  to the foot are anchored between the insole layer  108  and the outsole layer  112 . These straps include the center toe strap  104 , a rear strap  120  (shown in FIG.  12 ), and a single strap  122  (shown in FIG. 11) comprised of several strap sections discussed hereinbelow (and that collectively form the self-adjusting harness  102 ). In order to accommodate the anchoring of these straps between the insole layer  108  and the outsole layer  112 , the straps must be able to pass through these layers. Consequently, four slots  124 ,  126 ,  128  and  130  are cut into the insole layer  108  to enable the rear strap  120  and the single strap  122  to pass therethrough as shown in FIGS. 1,  11  and  12 . Additionally, a penetration  132  is also formed in the forward part of the insole layer  108  and the midsole layer  110  as shown in FIGS. 8 and 9. The four slots  124 ,  126 ,  128  and  130  and the penetration  132  are the origin of the five anchor points associated with the sandal of the present invention  100 . 
     In order to accommodate the rear strap  120  passing through the slots  124  and  126  and the single strap  122  passing through the slots  128  and  130 , a pair of channels  134  and  136  are cut into the midsole  110  as shown in FIG.  8 . When the rear strap  120  has passed through the slot  124 , it is then turned inward and laid flat into the channel  136  and subsequently circuited out of slot  126  as shown in FIGS. 8,  9  and  12 . Once the rear strap  120  is properly located, it is then cemented or bonded in position in channel  136 . Likewise, when single strap  122  has passed through slot  128 , it is then turned inward and laid flat into the channel  134  and subsequently circuited out of slot  130  as shown in FIGS. 8,  9  and  11 . Once the single strap  122  is properly located, it is also cemented or bonded with a suitable adhesive in position in channel  134 . Further, the center toe strap  104  is positioned into the penetration  132 , turned inward and then cemented or bonded in position as shown in FIG.  9 . Thereafter, the insole layer  108  is positioned over and bonded to the midsole layer  110  to complete the construction. The rear strap  120 , single strap  122  and center toe strap  104  are now properly anchored between the insole layer  108  and the outsole layer  112 . Use of the channels  134  and  136  has enabled the avoidance of lumps between the insole layer  108  and the outsole layer  112  that otherwise would be present. 
     We now turn our attention to the various strap sections that comprise the harness  102  as shown in FIG.  1 . As previously noted, the harness  102  is formed from the single strap  122  shown in FIG.  11 . However, when the single strap  122  emerges from the slots  128  and  130  in the insole layer  108 , it is advantageous to provide each section of the single strap  122  with a separate identification number. Consequently, the section of the single strap  122  emerging from the slot  128  is referred to as the front inside strap section  138 . The section of the single strap  122  emerging from the slot  130  is referred to as the front outside strap section  140 . Connected to a distal end  142  of the center toe strap  104  is a front buckle  144  having three slots  146 ,  148  and  150  formed therein. The distal end  142  of the center toe strap  104  wraps about the slot  146  as shown in FIG.  1 . Since the front buckle  144  is connected to the center toe strap  104 , the front buckle  144  is stationary in position and will not move during the self-adjustments of the harness  102 . The front inside strap section  138  is then circuited through the slot  148  formed in the front buckle  144 . Likewise, the front outside strap section  140  is then circuited through the slot  150  formed in the front buckle  144 . The front inside strap section  138  and the front outside strap section  140  in combination with the center toe strap  104  captures the metatarsal area for securing the sandal  100  to the forward part of the foot by limiting the forward and lateral motion of the foot (i.e., no forward or side movement of the foot). 
     Once the front inside strap section  138  passes through the slot  148  of the front buckle  144 , it becomes the inside lateral strap section  152  as shown in FIG.  1 . Likewise, once the front outside strap section  140  passes through slot  150  of the front buckle  144 , it becomes the outside lateral strap section  154 . The inside lateral strap section  152  and the outside lateral strap section  154  in combination serve to limit lateral movement of the foot within the sandal  100 . 
     The inside lateral strap section  152  is then circuited to an inside rear buckle  156  having slots  158 ,  160  and  162  formed therein best shown in FIG.  5 . Likewise, the outside lateral strap section  154  is then circuited to an outside rear buckle  164  having slots  166 ,  168  and  170  formed therein best shown in FIG.  4 . The inside lateral strap section  152  is circuited through slot  158  of the inside rear buckle  156  and becomes a first terminal end  172  of the single strap  122 . The outside lateral strap section  154  is then circuited through slot  166  of the outside rear buckle  164  and becomes a second terminal end  174  of the single strap  122 . The first terminal end  172  and the second terminal end  174  of the single strap  122  are engaged using a hook and loop fastener  176  to form an over-the-instep closure  178  as shown in FIG.  1 . The over-the-instep closure  178  functions as the single point where adjustments of the harness  102  are made. 
     The rear strap  120  best shown in FIG. 12 includes an inside rear strap section  180  and an outside rear strap section  182  shown extending above the insole layer  108  in FIG.  1 . The inside rear strap section  180  is looped about the slot  160  of the inside rear buckle  156  as shown in FIG.  5 . Likewise, the outside rear strap section  182  is looped about slot  168  of the outside rear buckle  164  as shown in FIG.  4 . The inside rear strap section  180  and the outside rear strap section  182  function to hold the inside rear buckle  156  and the outside rear buckle  164  in a stationary position. 
     The independent adjustable heel strap  106  shown in FIG. 1 is attached at a distal end  184  to slot  170  of the outside rear buckle  164  as shown in FIG.  1 . The heel strap  106  is then circuited around the back side of the sandal  100  and through slot  162  of the inside rear buckle  156 . That portion of the heel strap  106  extending through the slot  162  of the inside rear buckle  156  is then engaged with that portion of the heel strap  106  extending between the outside rear buckle  164  and the inside rear buckle  156 . The engagement is accomplished by using a hook and loop fastener  186  to form a heel closure  188  as shown in FIG.  1 . The heel closure  188  functions to prevent the foot from slipping out of the sandal  100 . The heel closure  188  also functions to (a) offset and equalize the tension in the inside rear buckle  156  caused by the tension in the inside lateral strap section  152  and to (b) offset and equalize the tension in the outside rear buckle  164  caused by the tension in the outside lateral strap section  154 . It is noted that the foot only escapes the harness  102  by moving backwards and the foot can only move backwards if the heel closure  188  and the over-the-instep closure  178  are released, i.e., the hook and loop fastener  186  and the hook and loop fastener  176  are respectively disengaged. 
     During operation, the sandal  100  is placed on the foot and the heel closure  188  is adjusted once. Thereafter, only the over-the-instep closure  178  needs to be adjusted. With one adjustment of the hook and loop fastener  176 , the harness  102  is tensioned and the sandal  100  fits snugly to the foot. The sandal  100  of the present invention includes the harness  102  that is active, i.e., continuously self-adjusting. This means that movements of the foot result in continuous adjustments in the tension of the single strap  122  for regulating and equalizing the tension in the harness  102 . This action is accomplished in the following way. 
     Notwithstanding the over-the-instep closure  178  is engaged, the front inside strap section  138  and the inside lateral strap section  152  are free to move through the front buckle  144 . Likewise, the front outside strap section  140  and the outside lateral strap section  154  are also free to move through the front buckle  144 . Once the heel closure  188  is adjusted, the independent adjustable heel strap  106  is stationary. Further, the front buckle  144  is fastened to the stationary center toe strap  104  and thus is itself stationary. Thus, the stationary front buckle  144  prevents the foot from moving forward or laterally. Consequently, movements of the foot affect the tension in (a) the front inside strap section  138  and the inside lateral strap section  152 , and (b) the front outside strap section  140  and the outside lateral strap section  154 . 
     For example, when the foot is extended outward during walking (i.e., when a step is taken), the toe section of the foot is raised which raises the forward portion of the sandal  100 . This motion increases the pressure on the instep area of the foot which tightens the over-the-instep closure  178  and draws any slack out of the inside lateral strap section  152  and the front inside strap section  138 , and the outside lateral strap section  154  and the front outside strap section  140 , respectively. This results in increased tension in the harness  102  about the metatarsal area of the foot. However, when the foot is lowered to land a step (and the toe section of the foot is lowered), the inside and outside lateral strap sections  152  and  154  are pulled forward. This is the case since there is less tension on the independent adjustable heel strap  106  at the rear portion of the sandal  100  because the ankle is tilted backwards. Thus, the extra slack in the adjustable heel strap  106  is taken up by the forward components of the harness  102  and the overall tension is regulated and equalized. 
     In another example, increasing the upward pulling force on the sandal  100  (such as if the sandal  100  is stuck in mud or wedged between rocks) increases the pressure on the instep area of the foot. Consequently, the forward strap sections of the single strap  122  are tensioned resulting in a tightening of the harness  102  about the metatarsal area. Likewise, movements of the foot that decrease the upward pulling force on the sandal  100  cause the harness  102  to relax about the metatarsal area. 
     It is noted that the corresponding (left foot) sandal that is a mate to the (right foot) sandal  100  shown in drawing FIGS. 1-12 is a mirror image of the sandal  100  of the present invention. The circuiting of the strap sections of the single strap  122  can be modified and the harness  102  will continue to function properly. The hook and loop fasteners  176  and  186  can be replaced with other equivalent mechanical attachment means. 
     The present invention provides novel advantages over other sandal footwear known in the art. A main advantage of the sandal  100  of the present invention is that the active, self-adjusting harness  102  is comprised of a single strap  122  which is circuited through each of the buckles  144 ,  156  and  164 . This design enables the formation of the over-the-instep closure  178  which requires minimum adjustments to attach the sandal  100  to the foot at a single closure point. Further, the stationary center toe strap  104  retains the front buckle  144  in a fixed position so that the front buckle  144  does not move toward the instep of the foot during adjustment of the harness  102 . Thus, the self-adjusting feature of the harness  102  will function properly. Additionally, under conditions when the bottom of the sandal  100  is stuck, for example, in mud or wedged between rocks, the harness  102  grips the foot tighter as the force employed to pull up on the sandal  100  is increased. This design improves the probability that the sandal  100  will remain on the foot. Additionally, the sandal  100  exhibits a lightweight robust construction that is economical to produce. 
     While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. 
     It is therefore intended by the appended claims to cover any and all such modifications, applications and embodiments within the scope of the present invention. Accordingly,