Patent Description:
Footwear typically includes a sole structure configured to be located under a wearer's foot to space the foot away from the ground. Sole structures may typically be configured to provide one or more of cushioning, motion control, and resiliency.

<CIT> describes flexible foot support members including a first plantar support member, a second plantar support member, and a flex joint connecting the first and second plantar support members. The flex joint (e.g., one or more hinge structures) allows movement of the first plantar support surface with respect to the second plantar support surface in at least one direction, and optionally stops or limits this relative movement in the opposite direction. Footwear and sole structures including such flexible foot support members may allow more natural motion and flexion of a wearer's foot during a variety of motions, such as various phases of a walking or running step cycle, during turn or cutting events, when jumping, etc. <CIT> describes an arch support for a sports shoe, in particular a mountaineering or hiking boot, having an anatomically shaped body made of plastic material, and a reinforcing insert embedded in the body. The insert has a longitudinally ribbed structure, a main portion extending along the sole of the foot and wide enough to impart a high degree of torsional rigidity to the arch support, and a narrow front appendix extending from the main portion and connected to the main portion substantially at the metatarsus.

The claimed invention is defined by the subject-matter of the independent claims <NUM> and <NUM>. Additional embodiments are defined in the dependent claims. A sole plate is provided that is tuned for stiffness, energy absorption, and direction of energy return with any or all of a varying thickness, non-parallel, longitudinally-extending ridges, and a generally spoon-shaped forefoot portion. More particularly, a sole structure for an article of footwear comprises a sole plate that includes a midfoot region, and at least one of a forefoot region or a heel region. The sole plate has a foot-facing surface with ridges extending longitudinally in the midfoot region and in the at least one of a forefoot region or a heel region. The sole plate has a ground-facing surface with grooves extending longitudinally in correspondence with the ridges. The ridges and the grooves are configured such that a thickness of the sole plate from the foot-facing surface to the ground-facing surface varies at a transverse cross-section of the sole plate through the ridges, or varies along a length of at least one of the ridges, or varies at both the transverse cross-section and along the length of the at least one of the ridges. The ridges, grooves, and a varied thickness as described may tune the stiffness and energy absorption of the sole plate for different zones while permitting a unitary, one-piece component of uniform material. The plate may function as a stiffness modifier within the sole structure.

The ridges have crests, and at least some of the crests may extend non-parallel with one another in a longitudinal direction of the sole plate. The grooves may also have crests, and at least some of the crests of the grooves may extend non-parallel with one another in the longitudinal direction.

The sole plate includes both the forefoot region and the heel region. The ridges and the grooves extend only in the midfoot region and the forefoot region, and the sole plate has an undulating profile at any transverse cross-section of the sole plate through the ridges. The transverse cross-section is a first transverse cross-section of the sole plate in the midfoot region, and the undulating profile of the sole plate at the first transverse cross-section includes a first set of multiple waves having crests at the ridges and having troughs between respective adjacent ones of the ridges. The undulating profile of the sole plate at a second transverse cross-section in the forefoot region includes a second set of multiple waves having crests at the ridges and having troughs between respective adjacent ones of the ridges. Waves of the first set each have a first wavelength, and waves of the second set each have a second wavelength greater than the first wavelength.

In one or more embodiments, a lateral-most one of the ridges may curve in the longitudinal direction to follow a curved lateral edge of the sole plate, and a medial-most one of the ridges may curve in the longitudinal direction to follow a curved medial edge of the sole plate. Because the ridges may be non-parallel, the wavelengths can be different at the different transverse cross-sections. Generally, ridges with shorter wavelengths are stiffer in compression than ridges with longer wavelengths.

The amplitude of the crests of the ridges is greater in a zone of the sole plate configured for relatively high compressive loads than in a zone of the sole plate configured for relatively low compressive loads. For example, at least some of the crests may have an amplitude in a rearward portion of the forefoot region that is greater than in a forward portion of the forefoot region and than in the midfoot region. The rearward portion may be configured to underlie the metatarsal-phalangeal joints of a wearer, thus increasing stiffness and energy-absorbing capability where loading is greatest.

In one or more embodiments, the sole plate may be a resilient material such that the crests of the ridges may decrease in elevation from a steady state elevation to a loaded elevation under a dynamic compressive load and may return to the steady state elevation upon removal of the dynamic compressive load. For example, the sole plate may be one of a fiber strand-lain composite, a carbon-fiber composite, a thermoplastic elastomer, a glass-reinforced nylon, wood, or steel. The sole plate may resiliently deform to absorb and return energy. The areas of greater amplitude can absorb more energy than those of less amplitude. When sandwiched between foam layers of less compressive stiffness, such as a resilient foam midsole layer overlying and underlying the sole plate, the foam layers may react against the sole plate when resiliently deforming, so that the sole plate acts as a moderator both of bending stiffness and compressive stiffness of the sole structure.

In one or more embodiments, the foot-facing surface may be concave in a longitudinal direction of the sole plate in a forefoot region of the sole plate, and the ground-facing surface may be convex in the longitudinal direction of the sole plate in the forefoot region, creating a spoon-shaped forefoot region. In one or more embodiments, the sole plate may also have a heel region, and the sole plate may slope in the longitudinal direction in the midfoot region from the heel region to the forefoot region. The sole plate may be biased to this spoon shape in the forefoot region. Bending of the sole plate in the longitudinal direction during dorsiflexion may store energy that is released after toe-off, with the sole plate unbending to its original biased, spoon shape at least partially in the direction of forward motion.

In one or more embodiments, the foot-facing surface may have an undulating profile at the transverse cross-section that may include multiple waves having crests at the ridges and having troughs between respective adjacent ones of the ridges. The crests at the ridges may be aligned with crests of the grooves. The thickness of the sole plate at the transverse cross-section may be less at the crests of the ridges than between the crests of the ridges and the troughs.

In one or more embodiments, the ground-facing surface may be flat between the grooves at the transverse cross-section.

In one or more embodiments, the sole plate may include both the forefoot region and the heel region, and may be a unitary, one-piece component.

The sole structure for an article of footwear comprises a sole plate including a midfoot region, a forefoot region, and a heel region. The sole plate has a foot-facing surface with ridges extending longitudinally such that the foot-facing surface has an undulating profile at a transverse cross-section of the sole plate through the ridges. The sole plate has a ground-facing surface with grooves extending longitudinally. At least some of the ridges of the foot-facing surface may extend non-parallel with one another, and at least some of the grooves of the ground-facing surface may extend non-parallel with one another in correspondence with the ridges. The ridges and the grooves are configured such that a thickness of the sole plate from the foot-facing surface to the ground-facing surface varies at the transverse cross-section, or varies along a length of at least one of the ridges, or varies at both the transverse cross-section and along the length of the at least one of the ridges. At least some of the ridges vary in amplitude in a longitudinal direction of the sole plate.

In one or more embodiments, the amplitude of at least some of the ridges may be greater in a rearward portion of the forefoot region than in a forward portion of the forefoot region, and greater in the rearward portion of the forefoot region than in the midfoot region.

The ridges have crests, and the sole plate may be a resilient material such that the crests of the ridges may decrease in elevation from a steady state elevation to a loaded elevation under a dynamic compressive load and may return to the steady state elevation upon removal of the dynamic compressive load.

The transverse cross-section is a first transverse cross-section of the sole plate in the midfoot region, and the undulating profile of the sole plate at the first transverse cross-section includes a first set of multiple waves having crests at the ridges and having troughs between respective adjacent ones of the ridges. The undulating profile of the sole plate at a second transverse cross-section in the forefoot region includes a second set of multiple waves having crests at the ridges and having troughs between respective adjacent ones of the ridges. Waves of the first set each have a first wavelength. Waves of the second set each have a second wavelength greater than the first wavelength. A lateral-most one of the ridges may curve in the longitudinal direction to follow a curved lateral edge of the sole plate. A medial-most one of the ridges may curve in the longitudinal direction to follow a curved medial edge of the sole plate.

In one or more embodiments, the foot-facing surface may be concave in the longitudinal direction in the forefoot region. The ground-facing surface may be convex in the longitudinal direction in the forefoot region. The sole plate may slope in the longitudinal direction in the midfoot region from the heel region to the forefoot region, and the ground-facing surface may be flat between the grooves at the transverse cross-section.

Referring to the drawings, wherein like reference numbers refer to like components throughout the views, <FIG> shows an embodiment of a sole plate <NUM> for an article of footwear <NUM>, such as the article of footwear <NUM> of <FIG>. More specifically, the sole plate <NUM> is included in a sole structure <NUM> of the article of footwear <NUM>. The sole plate <NUM> described herein is configured to moderate bending stiffness during dorsiflexion, and direct return energy to the foot at least partially in a forward direction when dynamic compressive loading is removed following dorsiflexion during a stride. More specifically, the sole plate <NUM> has varying, non-parallel ridges and grooves, and a general spoon shape, and resiliently deforms when under a dynamic load, storing elastic energy, and resiliently returns to an unloaded state when the dynamic load is removed, releasing the stored elastic energy.

As used herein, the term "plate", such as in sole plate <NUM>, refers to a member of a sole structure that has a width greater than its thickness and is generally horizontally disposed when assembled in an article of footwear that is resting on the sole structure on a level ground surface, so that its thickness is generally in the vertical direction and its width is generally in the horizontal direction. A plate need not be a single component but instead can be multiple interconnected components. Portions of a plate can be flat, and portions can have some amount of curvature and variations in thickness when molded or otherwise formed in order to provide a shaped footbed and/or increased thickness for reinforcement in desired areas.

With reference to <FIG>, the sole plate <NUM> has a forefoot region <NUM>, a midfoot region <NUM>, and a heel region <NUM>, and as such is referred to as a full-length sole plate <NUM> and is a unitary, one-piece component. Alternatively, in other embodiments, the sole plate <NUM> could include only a forefoot region <NUM> and midfoot region <NUM>, or only a midfoot region <NUM> and heel region <NUM>.

When a human foot <NUM> of a size corresponding with the sole structure <NUM> (see <FIG>) is supported on the sole structure, the forefoot region <NUM> generally includes portions of the sole plate <NUM> corresponding with the toes and the joints connecting the metatarsals with the phalanges of the foot <NUM> (interchangeably referred to herein as the "metatarsal-phalangeal joints" or "MPJ" joints). The midfoot region <NUM> generally includes portions of the sole plate <NUM> corresponding with an arch area of the human foot, including the navicular joint. The heel region <NUM> generally includes portions of a sole plate corresponding with rear portions of the foot <NUM>, including the calcaneus bone. The forefoot region <NUM>, the midfoot region <NUM>, and the heel region <NUM> may also be referred to as a forefoot portion, a midfoot portion, and a heel portion, respectively, and may also be used to refer to corresponding regions of an upper <NUM> shown in <FIG> and other components of the article of footwear <NUM>. The midfoot region <NUM> is disposed between the forefoot region <NUM> and the heel region <NUM> such that the forefoot region <NUM> is forward of (i.e., anterior to) the midfoot region <NUM> and the heel region is rearward of (i.e., posterior to) the midfoot region <NUM>.

The sole plate <NUM> has a first side <NUM> shown in <FIG>, also referred to as a foot-facing side <NUM> that includes a foot-facing surface <NUM>. As shown in <FIG>, the sole plate <NUM> also has a second side <NUM> referred to as a ground-facing side <NUM> that includes a ground-facing surface <NUM>. The foot-facing side <NUM> is closer to the foot <NUM> (shown in phantom in <FIG>) than is the ground-facing side <NUM> when the sole plate <NUM> is assembled in the article of footwear <NUM> and worn on a foot <NUM>. The foot-facing side <NUM> is above the ground-facing side <NUM> when the sole plate <NUM> is assembled in the article of footwear <NUM> and worn on the foot <NUM>. The sole plate <NUM> also has a curved lateral edge <NUM> and a curved medial edge <NUM>. The sole plate <NUM> is a sole plate for a right foot. It should be understood that a sole plate for a left foot is a mirror image of the sole plate <NUM>.

Referring to <FIG>, the foot-facing surface <NUM> has ridges <NUM> extending longitudinally in the midfoot region <NUM> and in the forefoot region <NUM>. The ridges <NUM> do not extend to the heel region <NUM>. The foot-facing surface <NUM> is generally flat in the heel region <NUM> as best shown in <FIG>. The ground-facing surface <NUM> has grooves <NUM> extending longitudinally in correspondence with the ridges <NUM>. In the embodiment shown, there are four ridges <NUM> and four grooves <NUM>. More specifically, as best shown in <FIG>, there are four ridges 40A, 40B, 40C, 40D in order between the medial edge <NUM> and the lateral edge <NUM>. The ridges 40A, 40B, 40C, 40D have crests 44A, 44B, 44C, 44D, respectively, that extend along the lengths of the respective ridges. A lateral-most one of the ridges 40D curves in the longitudinal direction to follow the curved lateral edge <NUM>, and the medial-most one of the ridges 40A curves in the longitudinal direction to follow the curved medial edge <NUM>. Stated differently, the ridge 40D curves relative to a longitudinal midline LM to generally follow the lateral edge <NUM>, and the ridge 40A curves relative to the longitudinal midline LM to generally follow the medial edge <NUM>. The longitudinal direction is generally a direction along a longitudinal midline LM of the sole plate <NUM>, and may be either a forward direction (i.e., from the midfoot region <NUM> toward the forefoot region <NUM>), or a rearward direction (i.e., from the forefoot region <NUM> toward the midfoot region <NUM>).

With reference to <FIG>, the foot-facing surface <NUM> is concave in a longitudinal direction of the sole plate <NUM> in the forefoot region <NUM>, and the ground-facing surface <NUM> is convex in the longitudinal direction of the sole plate <NUM> in the forefoot region <NUM>. The concavity of the foot-facing surface <NUM> and the convexity of the ground-facing surface <NUM> extend into the midfoot region <NUM> so that the midfoot region <NUM> and the forefoot region <NUM> together establish a spoon shape. Additionally, the sole plate <NUM> slopes in the longitudinal direction in the midfoot region <NUM> from the heel region <NUM> to the forefoot region <NUM>. More specifically, the midfoot region <NUM> slopes downward from the heel region <NUM> to the forefoot region <NUM> when the sole plate <NUM> is assembled in the sole structure <NUM> and the sole structure <NUM> rests on a level ground surface G as shown in <FIG>. <FIG> also illustrate the concavity of the foot-facing surface <NUM> and the convexity of the ground-facing surface <NUM> in the forefoot region <NUM>. In <FIG>, the sole plate <NUM> is shown with the lowest point resting on a level ground surface G (i.e., prior to installation in the sole structure <NUM>). The sole plate <NUM> slopes downward in the forefoot region <NUM> from a front edge <NUM>. The sole plate <NUM> slopes down in the midfoot region <NUM> relative to the heel region <NUM> which is level with a rear edge <NUM>. The front edge <NUM> is higher than the rear edge <NUM> when in this position.

As used herein, a transverse cross-section of the sole plate <NUM> through the ridges <NUM> is a cross-section perpendicular to the longitudinal midline LM, and includes the cross-sections of <FIG>. As best shown in <FIG>, at any particular transverse cross-section of the sole plate <NUM> through the ridges 40A, 40B, 40C, 40D, the crests 44A, 44B, 44C, 44D are equally spaced apart from one another. Stated differently, all adjacent crests 44A, 44B, 44C, 44D are equally-spaced. However, because the distance between the lateral edge <NUM> and the medial edge <NUM> varies along the length of the sole plate <NUM> (i.e., the sole plate <NUM> has different widths at different transverse cross-sections), the crests 44A, 44B, 44C, 44D extend non-parallel with one another in the longitudinal direction of the sole plate <NUM>.

With reference to <FIG>, there are four grooves 42A, 42B, 42C, 42D on the ground-facing surface <NUM>, in order, between the medial edge <NUM> and the lateral edge <NUM>. As is apparent in <FIG>, the grooves 42A, 42B, 42C, 42D do not extend to the heel region <NUM>, and the ground-facing surface <NUM> is generally flat in the heel region <NUM>. The ridges <NUM> and the grooves <NUM> extend only in the midfoot region <NUM> and the forefoot region <NUM>. The grooves 42A, 42B, 42C, 42D have crests 46A, 46B, 46C, 46D, respectively, that extend along the lengths of the respective grooves. A lateral-most one of the groove 42D curves in the longitudinal direction to follow the curved lateral edge <NUM>, and the medial-most one of the grooves 42A curves in the longitudinal direction to follow the curved medial edge <NUM>. Stated differently, the groove 42D curves relative to the longitudinal midline LM to generally follow the lateral edge <NUM>, and the groove 42A curves relative to the longitudinal midline LM to follow the medial edge <NUM>. Like crests 44A, 44B, 44C, 44D, at any transverse cross-section of the sole plate <NUM> through the ridges 40A, 40B, 40C, 40D, the crests 46A, 46B, 46C, 46D are equally spaced apart from one another (i.e., all adjacent crests 46A, 46B, 46C, 46D are equally-spaced) and the crests 46A, 46B, 46C, 46D extend non-parallel with one another in the longitudinal direction of the sole plate <NUM>.

The crests 46A, 46B, 46C, 46D of the grooves 42A, 42B, 42C, 42D are aligned with crests 44A, 44B, 44C, 44D of the ridges 40A, 40B, 40C, 40D. As used herein, the crests 44A, 44B, 44C, 44D are aligned with the crests 46A, 46B, 46C, 46D because the crests directly underlie the crests 44A, 44B, 44C, 44D along the length of the ridge 40A, 40B, 40C, 40D so that a line connecting crests of a corresponding ridge and groove (e.g., a line connecting crest 44A and crest 46A) is perpendicular to a line along the flat portions of the ground-facing surface <NUM> at the transverse cross-section. As is apparent in <FIG>, and <FIG>, the ground-facing surface <NUM> of the sole plate <NUM> is flat between the grooves <NUM> at any transverse cross-section.

Due to the ridges <NUM> and the grooves <NUM>, the sole plate <NUM> has an undulating profile at any transverse cross-section of the sole plate <NUM> through the ridges <NUM>. For example, the transverse cross-section of <FIG> is a first transverse cross-section of the sole plate <NUM> in the midfoot region <NUM>. The foot-facing surface <NUM> has an undulating profile P1 of the sole plate at the first transverse cross-section. The undulating profile P1 includes a first set of multiple waves W1, W2, W3, W4 having crests 44A, 44B, 44C, 44D at the ridges 40A, 40B, 40C, 40D, and having troughs 50A, 50B, 50C between respective adjacent ones of the ridges. Each of the waves W1, W2, W3, W4 is of an equal wavelength first L1.

The transverse cross-section at <FIG> is a second transverse cross-section of the sole plate <NUM> through the ridge <NUM> in the forefoot region <NUM>. The undulating profile P2 of the sole plate <NUM> at the second transverse cross-section includes a second set of multiple waves W1A, W2A, W3A, W4A having crests 44A, 44B, 44C, 44D at the ridges 40A, 40B, 40C, 40D, and having the troughs 50A, 50B, 50C between respective adjacent ones of the ridges. Each of the waves W1A, W2A, W3A, W4A is of an equal second wavelength L2. The second wavelength L2 is greater than the first wavelength L1 due to the greater width of the sole plate <NUM> (from the medial edge <NUM> to the lateral edge <NUM>) at the second transverse cross-section.

A third transverse cross-section of the sole plate <NUM> across the ridges <NUM> is shown in <FIG> and is positioned longitudinally between the first and second cross-sections of <FIG>. The undulating profile P3 of the sole plate <NUM> at the third transverse cross-section includes a third set of multiple waves W1B, W2B, W3B, W4B having the crests 44A, 44B, 44C, 44D at the ridges 40A, 40B, 40C, 40D, and having the troughs 50A, 50B, 50C between respective adjacent ones of the ridges. Each of the waves W1B, W2B, W3B, W4B is of an equal third wavelength L3. The third wavelength L3 is greater than the first wavelength L1 and the second wavelength L2 due to the width of the sole plate <NUM> at the third transverse cross-section being greater than that at the first transverse cross-section and greater than that at the second transverse cross-section. Generally, increasing the number of ridges <NUM> over a given width (i.e., decreasing the wavelength) increases the bending stiffness in the longitudinal direction of the sole plate <NUM>. The sole plate <NUM> is wider in the forefoot region <NUM> at the third transverse cross-section of <FIG> than in the midfoot region <NUM> at the first transverse cross-section of <FIG>. Because the ridges <NUM> are nonparallel and the wavelengths of the waves at a given transverse cross-section are equal, the sole plate <NUM> has the same number of ridges (four) over the forefoot region <NUM> and midfoot region <NUM>.

In addition to the number of ridges <NUM>, the thickness of the sole plate <NUM> and the amplitude of the crests 44A, 44B, 44C, 44D affect the bending stiffness as well as the energy return of the sole plate <NUM>. When the crests 44A, 44B, 44C, 44D are referred to generally herein, the reference numeral <NUM> may be used. The ridges <NUM> and the grooves <NUM> are configured such that a thickness of the sole plate <NUM> from the foot-facing surface <NUM> to the ground-facing surface <NUM> varies at a transverse cross-section of the sole plate <NUM> through the ridges <NUM> and varies along a length of at least one of the ridges <NUM>. For example, as shown at the transverse cross-section in <FIG>, the thickness T1 of the sole plate <NUM> at the crests <NUM> of the ridges <NUM> (as shown at crest 44D) is less than the thickness T2 of the sole plate <NUM> at a location between the crests of the ridges and the troughs. The sole plate <NUM> will thus tend to elastically deform under a dynamic compressive load applied to the foot-facing surface <NUM> beginning at the crests <NUM>. For example, the sole plate <NUM> may be a resilient material such that the foot-facing surface <NUM> including the crests <NUM> of the ridges <NUM> decreases in elevation under a dynamic compressive load from the steady state elevation shown with solid lines in <FIG> to a loaded elevation 24A shown in phantom in <FIG>, and returns to the steady state elevation upon removal of the dynamic compressive load. At the crest 44C, for example, the elevation decreases from elevation E1 to elevation E2. For example, the sole plate <NUM> may be a fiber strand-lain composite, a carbon-fiber composite, a thermoplastic elastomer, a glass-reinforced nylon, wood, steel, or combinations thereof.

The ability of and the degree to which the sole plate <NUM> elastically deforms is also tuned by varying the thickness of the sole plate <NUM> along the length of the ridges <NUM>, and by varying the amplitude of the crests <NUM> along the length of the ridges <NUM>. A comparison of the transverse cross-sections of <FIG> shows that the sole plate <NUM> is thinnest (i.e., has the least thickness) at the ridges <NUM> where the amplitude of the crests <NUM> is the highest (e.g., in <FIG>), and the thickens gradually at the crests <NUM> as the amplitude decreases, as can be seen in <FIG>.

The ability of and the degree to which the sole plate <NUM> elastically deforms is tuned by varying the thickness of the sole plate <NUM> along the length of the ridges <NUM>, and by varying the amplitude of the crests <NUM> along the length of the ridges <NUM>. When the crests 46A, 46B, 46C, 46D are referred to generally herein, the reference numeral <NUM> may be used. The amplitude of the crests <NUM> is greater in zones of the sole plate <NUM> configured for relatively high compressive loads than in zones of the sole plate <NUM> configured for relatively low compressive loads. For example, referring to <FIG>, at least some of the crests <NUM> may have an amplitude that is greater in a rearward portion 16A of the forefoot region <NUM> (e.g., including at the transverse cross-section of <FIG>) than in a forward portion 16B of the forefoot region (e.g., including at the transverse cross-section of <FIG>), and greater in the rearward portion 16A of the forefoot region <NUM> than in the midfoot region <NUM> (e.g., including at the transverse cross-section of <FIG>). The greater amplitude of the crests <NUM> enables greater energy absorption under sufficient dynamic loading as more elastic deformation can occur with a greater possible change in height of the crests <NUM> between a steady state elevation and a loaded elevation. In the embodiment of the sole plate <NUM>, the amplitude of the crests <NUM> at any given transverse cross-section is uniform. Stated differently, each of the crests 44A, 44B, 44C, 44D has the same amplitude at the cross-section of <FIG>, and has the same amplitude at the cross-section of <FIG> (although different from that at <FIG>), and has the same amplitude at the cross-section of <FIG> (although different from that at <FIG>).

Referring to <FIG>, the sole structure <NUM> includes a resilient foam midsole <NUM>. The sole structure <NUM> also includes discrete outsole elements <NUM>, or alternatively, could include a unitary outsole. The midsole <NUM> includes a first foam layer 60A secured to the foot-facing surface <NUM>, and a second foam layer 60B secured to the ground-facing surface <NUM>. The first and second foam layers 60A, 60B are separate components having different compressive stiffnesses. The first foam layer 60A may be more or less stiff than the second foam layer 60B. The first foam layer 60A and the second foam layer 60B may be the same material composition, with different densities to provide the different compressive stiffnesses, or may be different materials.

Alternatively, as shown in <FIG>, an alternative article of footwear <NUM> has a midsole <NUM> that includes first and second foam layers 160A, 160B that are portions of a single component (i.e., a single, unitary, one-piece resilient foam midsole <NUM>). The first and second resilient foam midsole layers 160A, 160B are an upper portion and a lower portion of a single resilient foam midsole <NUM> surrounding the sole plate <NUM>, and in one embodiment, may be formed by injecting foam around the sole plate. The first and second foam layers 160A, 160B are the same material and have the same compressive stiffness.

As indicated in <FIG>, the foam midsole <NUM> compresses between the foot <NUM> and the ground G under a dynamic compressive load and reacts against both the foot-facing surface <NUM> and the ground-facing surface <NUM> of the stiffer sole plate <NUM>. The first foam layer 60A and the second foam layer 60B resiliently deform under the dynamic compressive load. The dynamic compressive load is illustrated by distributed loads F1, F2, F3, F4, F5 having various magnitudes represented by the length of the arrows. The first and second foam layers 60A, 60B return energy upon removal of the dynamic compressive load. Under dynamic loading, the first foam layer 60A is compressed against the foot-facing surface <NUM>, and the second foam layer is compressed against the ground-facing surface <NUM>.

<FIG> shows the article of footwear in a resting position, under steady state loading by the foot <NUM>. <FIG> may also represent an interim position of the article of footwear <NUM> during a stride in which the sole structure <NUM> is flat on the ground G. <FIG> show the article of footwear <NUM> in progressive first, second, and third stages of motion during the stride. The first stage of motion show in <FIG> is the beginning of the stride, with the heel portion <NUM> of the sole structure <NUM> and at least part of the midfoot portion <NUM> lifted from the ground G and the forefoot portion <NUM> in contact with the ground G. The second stage of motion in <FIG> shows further lifting of the midfoot portion <NUM> of the sole structure <NUM> away from the ground surface G and the forefoot portion <NUM> in contact with the ground G. Finally, <FIG> shows the article of footwear <NUM> completely lifted away from the ground G, as may occur during running. During the stride, the sole plate <NUM> bends along its length (e.g., along its longitudinal midline LM shown in <FIG>). Progressive bending occurs in the forefoot region <NUM>, generally under the metatarsal-phalangeal joints of the foot <NUM>, when the foot <NUM> is dorsiflexed and increased loading is placed in the forefoot region <NUM> as the wearer's weight shifts to the forefoot.

The spoon shape of the sole plate <NUM>, best shown in <FIG>, including the concave foot-facing surface <NUM> and convex ground-facing surface <NUM> in the forefoot region <NUM> helps to encourage forward rolling of the foot <NUM>. When the foot <NUM> lifts the sole structure <NUM> away from the ground G in <FIG>, the compressive forces in the sole plate <NUM> above a neutral axis of the sole plate <NUM> to the foot-facing surface <NUM>, and tensile forces below the neutral axis to the ground-facing surface <NUM> are relieved, returning the sole plate <NUM> to its unloaded orientation shown in <FIG>, which is the same as in <FIG> except lifted from the ground. The internal compressive and tensile forces in the sole plate <NUM> due to the wearer bending the sole plate <NUM> are released as the sole plate <NUM> unbends creates a net force F at least partially in the forward direction.

Accordingly, as discussed herein the sole plate <NUM> is tuned by varying its thickness, the amplitude of crests of ridges, and by the spoon shape, all of which contribute to the energy absorption during dynamic compression and longitudinal bending, and subsequent energy return during forward strides.

To assist and clarify the subsequent description of various embodiments, various terms are defined herein.

"At least one", and "one or more" are used interchangeably to indicate that at least one of the items is present. As used herein, "at least some" of an item means at least two of the items.

For consistency and convenience, directional adjectives are employed throughout this detailed description corresponding to the illustrated embodiments. Those having ordinary skill in the art will recognize that terms such as "above", "below", "upward", "downward", "top", "bottom", etc., may be used descriptively relative to the figures.

The term "longitudinal", as used throughout this detailed description and in the claims, refers to a direction extending a length of a component. For example, a longitudinal direction of a shoe extends between a forefoot region and a heel region of the shoe. The term "forward" is used to refer to the general direction from a heel region toward a forefoot region, and the term "rearward" is used to refer to the opposite direction, i.e., the direction from the forefoot region toward the heel region. In some cases, a component may be identified with a longitudinal axis as well as a forward and rearward longitudinal direction along that axis.

The term "vertical", as used throughout this detailed description and in the claims, refers to a direction generally perpendicular to both the lateral and longitudinal directions. For example, in cases where a sole structure is planted flat on a ground surface, the vertical direction may extend from the ground surface upward. It will be understood that each of these directional adjectives may be applied to individual components of a sole structure. The term "upward" or "upwards" refers to the vertical direction pointing towards a top of the component, which may include an instep, a fastening region and/or a throat of an upper. The term "downward" or "downwards" refers to the vertical direction pointing opposite the upwards direction, and may generally point towards the sole structure, or towards the outermost components of the sole structure.

Claim 1:
A sole structure (<NUM>) for an article of footwear (<NUM>) comprising:
a sole plate (<NUM>) including a midfoot region (<NUM>), and the sole plate (<NUM>) further including a forefoot region (<NUM>) and a heel region (<NUM>);
wherein the sole plate (<NUM>) has a foot-facing surface (<NUM>) with ridges (<NUM>, 40A, 40B, 40C, 40D) extending longitudinally in the midfoot region (<NUM>) and in the at least one of a forefoot region (<NUM>) or a heel region (<NUM>);
wherein the sole plate (<NUM>) has a ground-facing surface (<NUM>) with grooves (<NUM>, 42A, 42B, 42C, 42D) extending longitudinally in correspondence with the ridges (<NUM>, 40A, 40B, 40C, 40D);
wherein the ridges (<NUM>, 40A, 40B, 40C, 40D) and the grooves (<NUM>, 42A, 42B, 42C, 42D) are configured such that a thickness of the sole plate (<NUM>) from the foot-facing surface (<NUM>) to the ground-facing surface (<NUM>) varies at a transverse cross-section of the sole plate (<NUM>) through the ridges (<NUM>, 40A, 40B, 40C, 40D), or varies along a length of at least one of the ridges (<NUM>, 40A, 40B, 40C, 40D), or varies at both the transverse cross-section and along the length of the at least one of the ridges (<NUM>, 40A, 40B, 40C, 40D);
wherein the ridges (<NUM>, 40A, 40B, 40C, 40D) and the grooves (<NUM>, 42A, 42B, 42C, 42D) extend only in the midfoot region (<NUM>) and the forefoot region (<NUM>);
wherein the sole plate (<NUM>) has an undulating profile at any transverse cross-section of the sole plate (<NUM>) through the ridges (<NUM>, 40A, 40B, 40C, 40D);
wherein the transverse cross-section is a first transverse cross-section of the sole plate (<NUM>) in the midfoot region (<NUM>);
wherein the undulating profile of the sole plate (<NUM>) at the first transverse cross-section includes a first set of multiple waves having crests at the ridges (<NUM>, 40A, 40B, 40C, 40D) and having troughs between respective adjacent ones of the ridges (<NUM>, 40A, 40B, 40C, 40D);
wherein the undulating profile of the sole plate (<NUM>) at a second transverse cross-section in the forefoot region (<NUM>) includes a second set of multiple waves having crests at the ridges (<NUM>, 40A, 40B, 40C, 40D) and having troughs between respective adjacent ones of the ridges (<NUM>, 40A, 40B, 40C, 40D);
wherein waves of the first set each have a first wavelength; and
wherein waves of the second set each have a second wavelength greater than the first wavelength.