Patent Description:
Conventional footwear has structural limitations that force the wearer to make difficult choices between style and comfort. As a result, many individuals endure significant foot pain, or elect to wear less attractive shoes or styles that may not be appropriate for the occasion. To address this problem, some women carry additional footwear in a car or large bag. However, a spare pair of conventional shoes is less than ideal because of size and bulk limitations on portability.

An example of conventional shoes and manufacturing processes thereof is described in <CIT>.

Lightweight rollable or foldable shoes are available that offer increased portability. However, such products do not contain the support, durability, comfort or style desired in a non-foldable shoe.

Moreover, prior art foldable shoes have outsoles that do not adequately protect the shoe midsole and upper, leading to premature wear of the shoe including tearing and damage to the shoe. Furthermore, such shoes are typically flimsy or, in other words, do not provide adequate support or protection of the foot. For instance, many foldable shoes have an overall spring constant that is, depending on the brand and model, between <NUM> Newton (N) / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch). Such shoes provide little or no resistance, protection and support, and thus are inadequate to wear for repeated or extended use, particularly outside or on rough terrain (e.g., dirty pavement, stones, etc.). Moreover, such shoes are not durable enough to last a normal shoe lifespan even with only moderate use. Therefore, while some footwear designs have attempted to bridge the gap between full time and portable shoes, there remains no practical solution.

In prior art shoe manufacturing processes, outsoles are sewn onto a midsole. These outsoles are at the bottom of the shoe and protect the midsole and upper from wear and tear and further provide support and rigidity to the entire shoe. After the outsoles have been sewn on, the midsole is sewn to the upper and an insole thereby forming a single seam. This single seam traverses the perimeter of the shoe and essentially delineates the shoe upper from the midsole. While such processes are advantageous because of manufacturing efficiencies, the drawback with such approaches is realized when one considers the properties of the outsoles. The sewing wheel of the sewing machine used to sew the midsole, the upper, and the insole together interferes with the outsoles previously sewn onto the midsole. As a result, a dilemma arises. The ideal outsole patches serve to <NUM>) protect the foot, <NUM>) provide comfort, and <NUM>) provide durability by protecting the seam attaching the midsole, outsole and insole. Thus, the ideal outsole patches are thick and wide such that the perimeter of the outsoles is close to the seam. Yet, as the outsole becomes thicker and is brought closer to the seam that attaches the upper, midsole and insole, the seam becomes more difficult and eventually impossible to stitch. Thus, prior art shoes are constructed with either (i) thin and wide or (ii) narrow and thick outsole patches. Moreover, prior art shoes are limited on their ability to add cushion inserts below the insole because such cushion inserts make the seam even less manageable and force more narrowing and thinning of the outsole patches leading to greater instability and/or lower durability of the shoe and protection of the foot. Thus, in prior art shoes, shoe comfort and durability is traded off for shoe stability. Thus, the dilemma become apparent. If the outsole is made thick and narrow, the lack of support due to the gap between the perimeter of the outsoles and the seam becomes noticeable and uncomfortable and the seam, upper and midsole are left exposed to the ground. If the outsole is made thin and wide, the lack of support due to the gap between the perimeter of the outsole and the seam is not as noticeable. However, in such instances, the upper, midsole and seam are exposed to the ground, the outsole wears more quickly and the shoe provides limited protection and comfort.

Given the above background, what is needed in the art are improved foldable shoe designs and improved shoe manufacturing processes.

The invention is defined by the independent claim. Optional features are disclosed by the dependent claims.

The present disclosure addresses the preceding and other shortcomings of the prior art by providing an improved foldable shoe. The disclosed shoes are a split-sole class of women's shoe that allows for the shoe to be folded and placed in a drawstring pouch. The split sole is defined by a heel outsole patch and a toe outsole patch with a spacing between the patches. Advantageously, the disclosed shoes combine an upper and a midsole at a seam with an insole added in separately. Thus, the insole is not concurrently stitched into the seam that joins the midsole to the upper. This allows for (i) the perimeter of the heel outsole patch and the toe outsole patch to be much closer to the seam joining the midsole to the upper, and (ii) the outsole patches to be thicker, thereby affording better protection of the seam, midsole, and upper, greater support and comfort to the foot, a more rigid footbed, and allows for the insertion of thicker more substantial cushioning.

In some embodiments, the outsole patches are both sewn and glued on. To facilitate sewing the patches on, deep grooves near the perimeter of each outsole patch are afforded. These deep grooves are used to form the seam between the patches and the midsole. The thread used to form this seam is better protected by the deep grooves thereby improving the durability of the shoe and preventing wear on the seam.

The disclosed shoes have an improved spring constant relative to known shoes in the women's split sole class. In some embodiments, the spring constant of the overall shoe is between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch) or between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch).

This improved spring force constant lends greater support and allows for prolonged periods of wear.

In some embodiments, in addition to providing a foam inlay that is often found in women's shoes, the disclosed shoes allow for the insertion of a cushion insert in the heel portion of the shoes to provide additional support and comfort. Moreover, this heel portion has greater thickness at the heel end of the shoe than at a position intermediate the heel and toe ends of the shoes. Such a tapered thickness provides additional comfort, support, and style.

While it is known to place an elastic restriction at the edge of the upper that receives a woman's foot, the disclosed shoes provide an improved design by terminating the elastic restriction in the heel portion of the shoe. In some embodiments, rather than using the elastic restriction, an embedded cushion (Achilles' cushion) is provided in order to provide greater comfort.

<FIG> respectively provide perspective, side, top, front and back views of a shoe in accordance with the disclosure. From the perspective and side views of <FIG> and <FIG>, and when worn, the shoe appears no different from a conventional rigid sole shoe. Yet the shoe affords flexibility in design, foldability, and comfort without dressing down the wearer's outfit. In some embodiments, a cushion insert absorbs impact to the foot from walking on hard surfaces. In some embodiments, an elastic restriction <NUM> runs around the top of the upper <NUM> to grip the foot and form a snug fit on feet of various sizes and shapes. However, the elastic restriction <NUM> is designed to not encircle the entire foot, by stopping short in the back where it would otherwise uncomfortably grip the Achilles tendon area. In some embodiments, an Achilles cushion <NUM> is embedded in the upper fold that would otherwise surround the elastic restriction <NUM> to increase comfort. Moreover, in some embodiments, the Achilles heel portion of the upper <NUM> is skived so as to reduce its depth. By skiving this portion of the shoe, the seam that would normally protrude and come into contact with the foot is reduced, resulting in greater comfort.

Elastic restriction <NUM> is affixed to the opening of the upper <NUM> so that, when worn, the opening of the upper <NUM> will stretch to the size of the foot. In some embodiments, the elastic restriction <NUM> is sewn and glued to the upper <NUM> so as to most securely affix the two materials. In some embodiments, the elastic restriction <NUM> is sewn but not glued to the upper <NUM>. By sewing the elastic restriction without glue, the maximum amount that the elastic can be stretched is increased. This allows for a more comfortable fit on more foot sizes. In addition, by not gluing the elastic the natural rebound rate of the elastic restriction is preserved, adding comfort and extending the useful life of the elastic.

Referring to <FIG>, a flexible insole <NUM> provides added comfort without compromising portability, and may be fixed or removable. Optionally, the flexible insole <NUM> provides arch support. The shoe further comprises a foam inlay <NUM> that is affixed by glue to the insole <NUM>. In some embodiments, a flexible arch support provides added comfort without compromising portability. The flexible arch support does not restrict folding of the shoe, and may be fixed or removable. In some embodiments, the midsole <NUM> is reinforced by affixing flexible material on the inside of the midsole, beneath the insole <NUM> (e.g., between midsole <NUM> foam inlay <NUM>). Reinforcement of the midsole <NUM> in this manner has several benefits. First, the flex points of the footwear are strengthened without compromising portability. Second, the portions of the midsole <NUM> most likely to suffer from destructive friction from contact with the walking surface are strengthened to better withstand that stress. Third, the portion of the midsole <NUM> that comes in contact with the edge of the toe outsole patch is made more resistant to tearing. In some embodiments such a reinforcement is in instead of foam inlay <NUM>. In some embodiments such a reinforcement is in addition to foam inlay <NUM>.

In some embodiments, a rigid insert is inserted in between foam inlay <NUM> and the midsole <NUM>. This rigid insert extends the width of the midsole <NUM>, and from the toe of the midsole <NUM> to no further than midpoint <NUM> at which the footwear is folded. By inserting the rigid insert in this manner, greater space is maintained when worn between the delicate portions of the footwear (e.g., upper <NUM>) and the walking surface. By increasing this space, durability is improved.

Continuing to refer to <FIG>, the shoe comprises three uniquely shaped elements: a midsole <NUM>, a heel outsole patch <NUM>, and a toe outsole patch <NUM>. In some embodiments, the midsole <NUM> is made of a flexible but durable material, such as high-quality leather. In some embodiments, the heel outsole patch <NUM> and toe outsole patch <NUM> are constructed from all weather, non-skid material. The heel outsole patch <NUM> and the toe outsole patch <NUM> are individually sewn to the midsole <NUM>. Materials required for the necessary durability and safety of a full-time shoe are too rigid to afford the necessary flexibility to be folded. The heel outsole patch <NUM> and the toe outsole patch <NUM> are distinct, and individually stitched to the midsole <NUM> with a spacing <NUM> between them for the shoe to be folded. The size and shape of the heel outsole patch <NUM> and the toe outsole patch <NUM> are designed to optimally balance durability, comfort, and practicality, with compact size and minimal weight. The shape of the heel outsole patch <NUM> and the toe outsole patch <NUM> maximize protection for the foot in a space efficient manner. In some embodiments, the contours of the heel outsole patch <NUM> and the toe outsole patch <NUM> are sloped to provide attractive additional height when worn, and increase the clearance between the midsole <NUM> and the ground when worn. In such embodiments, the slope is designed so that when two shoes are stacked, large meets small so as to significantly reduce the combined thickness of the compressed pair for increased portability.

The upper <NUM> of the shoe is made of a high quality flexible but durable material designed to withstand repeated folding at the center of the shoe, as well as long periods of storage in the folded position. Such materials reduce or eliminate cracking at the surface of the joint, and damage from contact with surfaces. The upper <NUM> is constructed and stitched in a manner to wrap around the top and sides of the foot. The specific proportion of upper to outsole also allows the soft upper <NUM> to mold to wide and narrow feet, molding to the unique shape of each wearer's foot, and adding comfort and style benefits. The proportion also reduces the bulk of the shoes in the folded state for storage and portability. A rounded toe cavity <NUM> and flexible wraparound upper design increases commercial appeal by reducing or eliminating the need for costly half-size and/or variable width inventory, while maintaining a durable and comfortable design. The design allows great flexibility for fashionable elements via the upper such as distinctive colors, textures and ornamentation. When worn, the shoe appears no different from conventional fixed sole footwear, adding style and the ability to be worn with more formal attire.

The self-contained collapsible tote bag with handles is not part of the present invention. Referring to <FIG>, a lightweight, durable, reusable, self-contained collapsible tote bag with handles that may be folded and compressed, and then stored in the compacting pouch (<FIG>) adds utility to the foldable shoe system. In typical embodiments pouch is made out of a two-way stretch material and is capable of self-folding into a shape that minimizes volume (e.g., an approximately spherical shape). In some embodiments, the stitching of the pouch facilitates this stretching (e.g., using a zigzag stitching). In some embodiments, a stretch thread material is used in such stitching.

Advantageously, the tote bag may be collapsed into a pocket of the tote bag. In some embodiments, this pocket is in the interior of the tote bag when the tote bag is in the unfolded state. In some embodiments the pocket is made out of an elastic material so that the tote bag is compressed when in the folded state. When desired, the tote expands to carry an alternate pair of shoes with sufficient volume for additional items. In some embodiments this pocket is made out of a two-way stretch material and is capable of self-folding into a shape that minimizes volume (e.g., an approximately spherical shape).

The pouch is not part of the present invention. Referring to <FIG>, a pouch made of stretch nylon, polyester or similar material adds functionality by safely and cleanly storing the foldable footwear and related items. The pouch compresses the footwear in their folded configuration for minimal size when stored or transported. A rounded edge on the bottom of the pouch further decreases volume and increases compression. The pouch is sized just smaller than the footwear to minimize bulk. A drawstring around the opening of the pouch further aids compression, and seals dirty shoes from purse or pocket contents. A pocket located on one side of the pouch allows for compressed storage of the tote bag and/or other items.

The disclosed foldable shoe design allows for footwear to be worn in a normal manner, consistent with conventional rigid sole products, and suitable for various surfaces, weather, fashions, etc. When storage or portability is desired, the shoes are folded manually at approximately their midpoint, thus reducing their length in half. In their folded configuration, the shoes can be stacked and placed in the compacting pouch for maximum compression and portability. Once stowed in the pouch, the pair requires roughly the space of a wallet, and may be carried in a purse or pocket.

Now that an overview of the inventive shoe has been disclosed, specific features and various embodiments of the disclosed shoes will now be described. Referring to <FIG>, illustrated is a shoe in accordance with the present disclosure. The shoe comprises an upper <NUM>. The upper <NUM> forms an interior portion <NUM> for receiving a foot of a woman. The interior portion includes a toe cavity <NUM> and a heel cavity <NUM>.

Referring to <FIG>, the shoe further comprises a midsole <NUM>. The midsole <NUM> has (i) a toe end <NUM>, (ii) a heel end <NUM>, (iii) an inner side <NUM> and (iv) an outer side <NUM>. A perimeter of the midsole <NUM> is stitched to the upper <NUM>. The stitching of the midsole <NUM> to the upper <NUM> thereby forms a bottom to the interior portion <NUM> that is bounded by a first seam <NUM>. A heel outsole patch <NUM> is stitched onto a heel portion of a first face of the midsole <NUM>. A toe outsole patch <NUM> is stitched onto a toe portion of the first face of the midsole <NUM>.

In typical embodiments, the heel outsole patch <NUM> and the toe outsole patch <NUM> are stitched onto the midsole before the midsole <NUM> has been stitched to the upper <NUM>.

Referring to <FIG>, there is a spacing <NUM> between (i) the heel outsole patch <NUM> stitched onto the heel portion of the first face of the midsole <NUM> and (ii) the toe outsole patch <NUM> stitched onto the toe portion of the first face of the midsole <NUM>. The spacing <NUM> extends from the inner side <NUM> to the outer side <NUM> of the midsole <NUM> and occupies a position intermediate the toe end <NUM> and the heel end <NUM> of the midsole <NUM> thereby permitting the entire shoe to fold about an axis <NUM> in the spacing <NUM> running between the inner side <NUM> and the outer side <NUM>. In some embodiments, the spacing is between <NUM> (<NUM>/<NUM> of an inch) and <NUM> (<NUM>/<NUM> of an inch). In some embodiments, the spacing is about <NUM> (<NUM>/<NUM> of an inch). In taking these measurements, an "average" distance between the heel outsole patch <NUM> and the toe outsole patch <NUM> across the region bounded by the inner side <NUM> and the outer side <NUM> may be taken. For example, at several different points in the region bounded by the inner side <NUM> to the outer side <NUM>, the distance between the edge of the heel outsole patch <NUM> and the edge of the toe outsole patch <NUM> may be measured and these measurements may be averaged together to determine the distance between the heel outsole patch <NUM> and the toe outsole patch <NUM>. In some embodiments the spacing is simply a break between the heel outsole patch <NUM> and the toe outsole patch <NUM>.

Continuing to refer to <FIG>, the insole <NUM> is affixed by glue to the bottom of the interior portion.

The shoe is configured to fold between (i) an extended state wherein the heel outsole patch <NUM> and the toe outsole patch <NUM> are coplanar or approximately coplanar (<FIG>) and (ii) a folded state in which the shoe is bent about the axis <NUM> such that a portion of the upper <NUM> comprising the toe cavity <NUM> is tucked into the heel cavity <NUM> (<FIG>).

In some embodiments, the insole <NUM> is not stitched to the upper <NUM>. Thus, in such embodiments, the first seam <NUM>, illustrated in <FIG>, only joins the upper <NUM> and the midsole <NUM>, not the insole <NUM>. Referring to <FIG>, this affords a substantial advantage because it allows a perimeter (edge) of the heel and toe outsole patches <NUM>, <NUM> to be brought closer to the first seam <NUM> than in instances where the first seam binds the upper <NUM>, midsole <NUM> and the insole <NUM> together, and allows for thicker heel and toe outsole patches, and more substantial (thicker, and more rigid) cushioning in the insole. This distance is illustrated as distance <NUM> in <FIG>. Accordingly, in embodiments where the first seam <NUM> only joins the upper <NUM> and the midsole <NUM>, the edge of the back corner <NUM> of the toe outsole patch <NUM> is within <NUM> (<NUM>/<NUM> of an inch) of a portion of the first seam <NUM>. This proximity to the seam <NUM>, along with the thickness of the outsole patches, advantageously serves to protect the first seam <NUM> as well as the region of the midsole <NUM> in the spacing <NUM> from wear and tear. In some embodiments, an edge of front corner <NUM> of the toe outsole patch <NUM> is within <NUM> (<NUM>/<NUM> of an inch) of a portion of the first seam <NUM>.

In typical embodiments, the distance <NUM> between the edge of the toe outsole pouch <NUM> and the first seam <NUM> is uniform. In some embodiments in which this distance <NUM> is uniform, (i) the edge of the back corner <NUM> and (ii) the edge of the front corner <NUM> of the toe outsole patch <NUM> are respectively within <NUM> (<NUM>/<NUM> of an inch), <NUM> (<NUM>/<NUM> of an inch), or <NUM> (<NUM>/<NUM> of an inch) of a corresponding portion of the first seam <NUM>.

In some embodiments, an edge of the back corner <NUM> of the heel outsole patch <NUM> is within <NUM> (<NUM>/<NUM> of an inch) of a portion of the first seam <NUM>. In some embodiments, an edge of the front corner <NUM> of the heel outsole patch <NUM> is between <NUM> (<NUM>/<NUM> of an inch) and <NUM> (<NUM>/<NUM> of an inch) of a portion of the first seam <NUM>. In some embodiments, the distance <NUM> between the edge of the heel outsole pouch <NUM> and the first seam <NUM> is uniform. In some embodiments in which this distance <NUM> is uniform, (i) the edge of the back corner <NUM> and (ii) the edge of the front corner <NUM> of the heel outsole patch <NUM> are respectively within <NUM> (<NUM>/<NUM> of an inch), <NUM> (<NUM>/<NUM> of an inch), or <NUM> (<NUM>/<NUM> of an inch) of a corresponding portion of the first seam <NUM>. In some embodiments, the distance <NUM> between the edge of the heel outsole pouch <NUM> and the first seam <NUM> is not uniform. In some embodiments in which this distance <NUM> is not uniform, the edge of the back corner <NUM> of the heel outsole patch <NUM> is within <NUM> (<NUM>/<NUM> of an inch), or <NUM> (<NUM>/<NUM> of an inch) of a corresponding portion of the first seam <NUM>.

Such proximate distances <NUM>, combined with the thickness of the rubber and rigidity of the cushioning enabled by the described method of assembly, facilitate the protection of the midsole <NUM> and the upper <NUM>, thus ensuring the durability of the shoe while at the same time allowing for a foldable design that remains flexible and comfortable.

Referring to <FIG>, a unique and improved feature of the present shoes is the value of a durability coefficient. As used herein, the term "durability coefficient" is defined as the thickness <NUM> of an outsole patch divided by the distance <NUM> between the edge of the outsole patch and the first seam <NUM>. In some embodiments, the distance <NUM> is <NUM> and the thickness <NUM> is also <NUM> and thus the durability coefficient is unity. In some embodiments, the distance <NUM> is <NUM> and the thickness <NUM> is <NUM> and thus the durability coefficient is <NUM>. The durability coefficient is between <NUM> and <NUM>. In some embodiments, the durability coefficient is between <NUM> and <NUM>. In some embodiments, the durability coefficient is between <NUM> and <NUM>.

In some embodiments, advantageously, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each at least <NUM> (<NUM>/<NUM> of an inch) thick. In some embodiments, advantageously, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each at least <NUM> (<NUM>/<NUM> of an inch) thick. In some embodiments, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each at least <NUM> (<NUM>/<NUM> of an inch) thick. In some embodiments, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each at least <NUM> (<NUM>/<NUM> of an inch) thick. In some embodiments, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each at least <NUM> (<NUM>/<NUM> of an inch) thick. In some embodiments, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each at least <NUM> (<NUM>/<NUM> of an inch) thick. Such thickness increases the spring constant of the soles, leading to greater support for the foot and increased durability of the shoe. Referring to <FIG>, because of the thickness of the outsole patches, and their proximity to the edge, it is possible to view a side of the outsole patch at least at a <NUM>-degree angle <NUM> from the horizontal <NUM> when the shoe is worn on a woman's foot when the woman is standing upright with respect to the horizontal. In some embodiments, it is possible to view a side of the outsole patch at least at a <NUM> degree angle, at least a <NUM> degree angle, or at least a <NUM> degree angle <NUM> from the horizontal <NUM> when the shoe is worn on a woman's foot when the woman is standing upright with respect to the horizontal. This visibility of the outsole patches is described herein solely to set forth a description of the dimensions and shapes of the disclosed shoes.

In some embodiments, the heel outsole patch <NUM> and the toe outsole patch <NUM> are each made out of an elastomer. Exemplary elastomers that may be used include but are not limited to, for example, natural rubber, vulcanized natural rubber, a butadiene-styrene copolymer such as GR-S, neoprene, nitrile rubbers, butyl, polysulfide rubbers, ethylene-propylene rubbers, polyurethane rubbers, and silicone rubbers as described in<NPL>. In some embodiments the midsole <NUM> is made out of leather.

Referring to <FIG>, the shoe comprises a midsole <NUM>. A heel outsole patch <NUM> and a toe outsole patch <NUM> are sewn onto a first face of the midsole <NUM>. The midsole <NUM> comprises a second face having a heel portion <NUM> and a toe portion <NUM>. In some embodiments, a cushion insert <NUM> is glued to the heel portion <NUM> of a second face of the midsole <NUM>. The insert <NUM> absorbs impact to the foot when walking on hard surfaces. The insert <NUM> molds to the foot over time. A foam inlay <NUM> is glued to (i) the cushion insert <NUM> and (ii) the toe portion <NUM> of the second face of the midsole <NUM>. Next an insole <NUM> is affixed by glue to the foam inlay <NUM>. The cushion insert <NUM> is characterized by a first end <NUM> and a second end <NUM>. The first end <NUM> of the cushion insert <NUM> is glued to a first part <NUM> of the heel portion <NUM> and the second end <NUM> of the cushion insert <NUM> is glued to a second part <NUM> of the heel portion <NUM>. The first part <NUM> of the heel portion <NUM> is closer to the toe portion <NUM> of the second face of the midsole <NUM> than the second part <NUM> of the heel portion <NUM>. In some embodiments, the first end <NUM> of the cushion insert <NUM> has a thickness that is less than the thickness of the second end <NUM> of the cushion insert <NUM>. In some embodiments, the cushion insert <NUM> has a thickness that increases along the cushion insert <NUM> as a function of a distance away from the toe portion <NUM> of the second face of the midsole <NUM> so that a portion of the cushion insert that is closest to the toe portion <NUM> of the midsole is thinner than a portion of the cushion insert <NUM> that is farthest away from the toe portion <NUM> of the midsole <NUM>. In some embodiments, the maximum thickness of the cushion insert <NUM> is <NUM> millimeters or more, <NUM> millimeters or more, <NUM> millimeters or more, <NUM> millimeters or more, <NUM> millimeters or more, or <NUM> millimeters or more. This advantageously serves to improve the support provided by the shoe, particularly at the heel, provides desired lift, and increases rigidity and thereby durability.

In addition to providing a graduated thickness to improve foot support, the cushion insert <NUM> is made out of a rigid material such as a rigid ethylene vinyl acetate or similar cushion material. In some embodiments, the cushion insert <NUM> has a Shore A hardness of between <NUM> and <NUM> or between <NUM> and <NUM>. In some embodiments, the cushion insert <NUM> has a density of between <NUM>/cm<NUM> and <NUM>/cm<NUM>, between <NUM>/cm<NUM> and <NUM>/cm<NUM>, between <NUM>/cm<NUM> and <NUM>/cm<NUM>, or between <NUM>/cm<NUM> and <NUM>/cm<NUM>.

The thickness of the heel outsole patch <NUM> and the toe outsole patch <NUM> together with the materials used to make these patches, the proximity of these patches to the seam <NUM> and the ability to add the cushion insert, contributes to a greatly improved spring constant relative to known foldable shoes. In some embodiments, the overall spring constant of the shoe taken lengthwise in the heel portion <NUM> of the shoe (i.e., in the region of the heel outsole patch <NUM>) is between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch). In some embodiments, the overall spring constant of the shoe taken lengthwise in the heel portion <NUM> of the shoe is between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch), or between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch). In some embodiments, the overall spring constant of the shoe taken lengthwise in the heel portion <NUM> of the shoe is about <NUM> N / cm (<NUM> kilogram-force / inch). Referring to <FIG>, to arrive at the spring constant measurement, the portions <NUM> and <NUM> are measured separately. For each region, with the shoe held in an upright position one end (i.e., one end of portion <NUM> or <NUM> going the long way and with shoe facing up as it would be worn) is anchored and then the other end of the portion <NUM> or <NUM> of the shoe being measured is forced down a set distance (e.g., <NUM> (<NUM> inch)) and the force exerted by the pushed down end is then measured.

In some embodiments, the overall spring constant of the shoe taken lengthwise in the toe portion <NUM> of the shoe (i.e., in the region of the toe outsole patch <NUM>) is between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch). In some embodiments, the overall spring constant of the shoe taken lengthwise in the toe portion <NUM> of the shoe is between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch) or between <NUM> N / cm (<NUM> kilogram-force / inch) and <NUM> N / cm (<NUM> kilogram-force / inch). In some embodiments, the overall spring constant of the shoe taken lengthwise in the toe portion <NUM> of the shoe is about <NUM> N / cm (<NUM> kilogram-force / inch).

Another advantageous feature of the shoes in accordance with some embodiments of the present disclosure are deep grooves in the heel outsole patch <NUM> and the toe outsole patch <NUM> that facilitate the stitching of the patches to the midsole <NUM> while at the same time protecting the stitching. The deep grooves <NUM> are enabled by the advantageous design in which thick outsole patches are employed that, at the same time, are proximate to the first seam <NUM> which attaches the upper <NUM> to the midsole <NUM>. The deep grooves <NUM> protect the stitching that attaches the outsole patches to the midsole <NUM> from contact with the ground, which would cause the stitching to wear and thereby cause the outsole patches to become detached. These advantageous features are related. By only stitching the upper <NUM> to the midsole <NUM> to form the first seam, rather than further stitching insole <NUM> to the midsole <NUM>, it is possible to both minimize distance <NUM> and increase thickness of the outsole patches <NUM>/<NUM> while still being able to stitch the midsole <NUM> to the upper <NUM> using conventional processes such as a sewing machine. Because distance <NUM> is minimized, it is possible to make the outsole patches <NUM>/<NUM> thicker (i.e., increase distance <NUM>) without destabilizing foot support. Because the outsole patches <NUM>/<NUM> are thicker, it is possible to make the first groove <NUM> deeper thereby better protecting the stitching within the groove. Moreover, because the outsole patches are thicker, the shoe is firm and allows for use for longer periods of time and a greater spectrum of terrain (e.g., on asphalt, concrete, dirt roads, etc.) Referring to <FIG>, one such advantageous embodiment has a first groove <NUM> having a depth of at least <NUM> (<NUM>/<NUM> of an inch) that is formed proximate to a perimeter of the heel outsole patch <NUM>. The heel outsole patch <NUM> is stitched onto the heel portion of the first face of the midsole <NUM> with a first thread that occupies the first groove <NUM>. Further, a second groove <NUM> having a depth of at least <NUM> (<NUM>/<NUM> of an inch) is formed proximate to a perimeter of the toe outsole patch <NUM>. The toe outsole patch <NUM> is stitched onto the toe portion of the first face of the midsole <NUM> with a second thread that occupies the second groove <NUM>. In some embodiments, the first groove <NUM> is about <NUM> (<NUM>/<NUM>) of an inch. In some embodiments, the second groove <NUM> is about <NUM> (<NUM>/<NUM> of an inch).

Referring to <FIG>, the upper <NUM> is formed as a single piece having a first end and a second end, where the first end and the second end are united by a second seam <NUM> at the heel cavity. In some embodiments upper <NUM> is formed of two or more pieces.

Referring to <FIG> and <FIG>, in typical embodiments, the upper <NUM> is formed as a single piece having (i) a first end (<NUM>), (ii) a second end (<NUM>), (iii) a first edge (<NUM>) (visible in <FIG>), and (iv) a second edge (<NUM>). In some embodiments, upper <NUM> is formed of two or more pieces sewn together. Referring to <FIG>, in typical embodiments, upper <NUM> is a single piece having ends 110A and 110B. Of course, upper <NUM> may be formed by any number of pieces sewn together into a single piece having ends 110A and 110B. Regardless of whether upper originates as one or multiple pieces, ends 110A (first end) and 110B (second end) are united by a second seam <NUM> at the heel cavity <NUM> to complete the upper <NUM>. Referring to <FIG>, the first edge <NUM> of the upper <NUM> is stitched to the perimeter of the midsole <NUM> thereby forming the second seam <NUM> and the bottom to the interior portion of the shoe. Referring back to <FIG>, a first portion of the second edge <NUM> is characterized by an elastic restriction <NUM>, where the portion of the second edge does not extend to the heel cavity <NUM>. In some embodiments, the second portion of the second edge <NUM> is characterized by an Achilles cushion <NUM> that provides an upper boundary to the heel cavity <NUM>. Further, referring to <FIG>, in some embodiments, a half moon piece <NUM> covers a lower portion of the second seam <NUM> whereas a strip portion <NUM> covers an upper portion of the second seam <NUM>.

Referring to <FIG>, in some embodiments, the shoe is in a folded state. In this folded state, the shoes can be tucked into a stretch nylon or similar material compacting pouch (<FIG>), having a drawstring (the pouch is not part of the present invention). This provides for the advantageous transport of the shoes in a clean and compact state, while compressed into a minimal size. In some embodiments, the pouch include a pocket for holding a tote bag, where the tote bag is configured to accommodate a pair of women's shoes, or other items and personal effects. This allows for the possibility of carrying the shoes of the present disclosure in the pouch, while on the road, and switching to wearing the shoes of the present disclosure by storing unwanted previously worn shoes in the tote bag after it has been removed from the pocket of the pouch, and expanded from its collapsed form.

Advantageously, the shoes of the present disclosure tuck into a folded state so that they may be stored in a compact box having a lid (the compact box having a lid is not part of the present invention). Such a compact box is illustrated in <FIG>.

In some embodiments, the edge of the outsole patches are beveled in two ways. First, outside edge of the outsole patch is beveled at steep incline for durability and aesthetic reasons. By preserving a steep bevel on the outside edge of the outsole patches, a greater space is maintained between the walking surface and soft elements of the footwear, thereby increasing durability. Second, in some embodiments the interior edge of one or more outsole patches is beveled. By beveling the outsole patch in this manner, pressure between the edge of the outsole patch and the softer midsole is reduced. This beveling blunts and softens the edge of the outsole patch that is not affixed to the midsole. By softening this edge, durability and longevity of the footwear is improved.

As discussed above, prior art split sole footwear suffer from certain limitations. In some embodiments, the shortcomings of the prior art are overcome by providing shoes that achieve a maximum outsole ratio (OR), where OR is defined as: <MAT> where,.

Accordingly, in some embodiments, the shoes of the present disclosure have an outsole ratio OR. When this ratio is maximized, the toe outsole patch <NUM> is thick, the second groove <NUM> in which the toe outsole patch <NUM> stitching is made is deep, and the toe outsole patch <NUM> is close to the edge of the footwear. In some embodiments, an acceptable outsole ratio requires a toe outsole patch <NUM> that is as narrow as possible while still able to accommodate a wide range of foot widths. The more narrow the toe outsole patch <NUM>, the more compact and portable the footwear, and the better it will accommodate a narrow foot. A thicker toe outsole patch <NUM> is important to foot safety and comfort when walking on uneven surfaces.

Further, as the width of the toe outsole patch <NUM> is narrowed, the depth of the second groove <NUM> for its stitching becomes more important because that seam area will receive more contact with the walking surface. Thus, a deep groove <NUM> is necessary to protect the seam stitching. Also increasing in importance as the width of the toe outsole patch <NUM> is narrowed is the coverage of midsole <NUM> by the toe outsole patch <NUM> and its proximity to the edge of the upper <NUM>. The benefits of a toe outsole patch <NUM> that is closer to the edge of the footwear have been presented above. Given the present disclosure, it will be appreciated that these same principles apply to the heel outsole patch <NUM> and first groove <NUM>.

Table <NUM> below illustrates preferred values for average depth of second groove <NUM> (D), average thickness of toe outsole patch <NUM> (T), maximum width of toe outsole patch <NUM> (W), and width of midsole <NUM> at point of maximum width of toe outsole patch <NUM> (M) in accordance with an embodiment of the present disclosure.

In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. In some embodiments, the shoes of the present disclosure has an outsole ratio of <NUM> or greater. By achieving an outsole ratio of this magnitude, several benefits arise which increase the viability of split sole footwear.

Tables <NUM> and <NUM> below illustrate preferred values for average depth of second groove <NUM> (D), average thickness of toe outsole patch <NUM> (T), maximum width of toe outsole patch <NUM> (W), and width of midsole <NUM> at point of maximum width of toe outsole patch <NUM> (M) in accordance with embodiments of the present disclosure.

In some embodiments, a shoe is provided that achieves a maximum outsole ratio (OR), where OR is defined as: <MAT> where,.

In some embodiments, T' has a value of at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>.

A first benefit of the shoes satisfying the OR metric is improved comfort. Thicker outsole patches allows for more cushion between foot and walking surface and minimizes the impact of hard objects. Wide outsole patches that are closer to the edge of the shoe covers more of bottom of foot, preventing the foot from the uncomfortable feeling putting pressure on the edge of the outsole or worse, hanging over the edge of the rubber.

A second benefit is improved protection of the foot. Thicker outsoles provide more of a barrier and thus more protection to the foot against hard or sharp objects. Further, wider outsoles provide more protection and coverage of the foot.

A third benefit is enhanced durability. Outsoles close to the edge of the shoe protects the seam stitching, outsole (<NUM>, <NUM>), midsole (<NUM>), and other delicate elements of the shoe. Thicker outsoles (<NUM>, <NUM>) provide more outsole to wear down before delicate parts of the shoe (e.g., midsole <NUM>) wear out from contact with ground. A deeper groove (e.g., first groove <NUM> and second groove <NUM>) protects outsole stitching better so it doesn't wear out as quickly.

A forth benefit is that it enables a more attractive style: the narrower shoe flexes to adapt to wider feet when necessary. This is accomplished by a deep groove (e.g., first groove <NUM> and second groove <NUM>) that protects stitching from increased contact that the groove, and thus the stitching therein, has with ground on narrower shoe. This is further accomplished by a thick outsole patch (e.g., heel outsole patch <NUM> and toe outsole patch <NUM>) that is close to the edge that becomes increasingly important on narrow shoes as some feet are wider than the outsole. Here, the outsole thickness prevents wider feet from pushing seam / midsole <NUM>/ upper <NUM> down on to ground.

A fifth benefit is that the shoe is more portable and compact because the non-foldable heel outsole patch <NUM> and toe outsole patch area is minimized.

The following are nonlimiting examples of the present disclosure. Optional features are defined in the dependent claims.

Many modifications and variations of this invention can be made as will be apparent to those skilled in the art. The specific embodiments described herein are offered by way of example only. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

This disclosure extends to various footwear styles (in addition to the basic ballet flat/slipper depicted in the diagrams). For example: sandals, flip-flops, active and athletic shoes can be made with a similar construction for flexible compression and compact storage and are fully encompassed within the scope of the present invention. Moreover, while embodiments have been disclosed that are designed for woman, it will be appreciated that such shoes can be designed for men, children, or any combination of woman, men, and children. All such alternative designs are fully within the scope of the present disclosure.

Claim 1:
A shoe comprising:
an upper (<NUM>), the upper forming an interior portion (<NUM>) for receiving a foot, the interior portion including a toe cavity (<NUM>) a heel cavity (<NUM>), and a first edge;
a midsole (<NUM>), the midsole having (i) a toe end (<NUM>), (ii) a heel end (<NUM>), (iii) an inner side (<NUM>), and (iv) an outer side (<NUM>), wherein a perimeter of the midsole is stitched to the first edge of the upper thereby forming a bottom to the interior portion;
a heel outsole patch (<NUM>) stitched to a heel portion (<NUM>) of a first face of the midsole;
a toe outsole patch (<NUM>) stitched to a toe portion (<NUM>) of the first face of the midsole;
an insole (<NUM>) that is affixed to the bottom of the interior portion; wherein
there is a spacing (<NUM>) between (i) the heel outsole patch stitched to the heel portion of the first face of the midsole and (ii) the toe outsole patch stitched to the toe portion of the first face of the midsole, the spacing extending from the inner side to the outer side and occupying a position intermediate the toe end and the heel end thereby permitting the entire shoe to fold about an axis (<NUM>) in the spacing running between the inner side and the outer side,
the shoe is configured to fold between (i) an extended state wherein the heel outsole patch and the toe outsole patch are coplanar and (ii) a folded state in which the shoe is bent about the axis such that a portion of the upper comprising the toe cavity is tucked into the heel cavity, and
the toe outsole patch or the heel outsole patch has a durability coefficient of between <NUM> and <NUM>.