Boots – shoes – and leggings – Soles – Cushion
Reexamination Certificate
2001-01-02
2002-12-03
Patterson, M. D. (Department: 3728)
Boots, shoes, and leggings
Soles
Cushion
C036S03500R, C036S037000, C036S114000
Reexamination Certificate
active
06487796
ABSTRACT:
TECHNICAL FIELD
The invention relates to footwear, more particularly to athletic shoes, wherein a cushioning sole is provided with a stability control device to enhance the stability of a wearer's foot, particularly during lateral motion. The sole includes a sole member which is compressible and resilient to thereby cushion foot impact, with the sole member having a stability control device that enhances lateral stability.
BACKGROUND OF THE INVENTION
Sole design for modem athletic footwear is generally characterized by a multi-layer construction comprised of an outsole, midsole, and insole. The midsole is typically composed of a soft, foam material to attenuate impact forces generated by contact of the footwear with the ground during athletic activities. Other prior art midsoles use fluid or gas-filled bladders of the type disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 of Marion F. Rudy. Although foam materials succeed in providing cushioning for the foot, foam materials also impart instability that increases in proportion to midsole thickness. For this reason, footwear design often involves a balance of cushioning and stability.
The typical motion of the foot during running proceeds as follows. First, the heel strikes the ground, followed by the ball of the foot. As the heel leaves the ground, the foot rolls forward so that the toes make contact, and finally the entire foot leaves the ground to begin another cycle. During the time that the foot is in contact with the ground, it typically rolls from the outside or lateral side to the inside or medial side, a process called pronation. That is, normally, the outside of the heel strikes first and the toes on the inside of the foot leave the ground last. While the foot is air borne and preparing for another cycle the opposite process, called supination, occurs. Pronation, the inward roll of the foot in contact with the ground, although normal, can be a potential source of foot and leg injury, particularly if it is excessive. The use of soft cushioning materials in the midsole of running shoes, while providing protection against impact forces, can encourage instability of the sub-talar joint of the ankle, thereby contributing to the tendency for over-pronation. This instability has been cited as a contributor to “runners knee” and other athletic injuries.
Various methods for resisting excessive pronation or instability of the sub-talar joint have been proposed and incorporated into prior art athletic shoes as “stability” devices. In general, these devices have been fashioned by modifying conventional shoe components, such as the heel counter, by modifying the midsole cushioning materials or adding a pronation control device to a midsole. Examples of these techniques are found in U.S. Pat. Nos. 4,288,929; 4,354,318; 4,255,877; 4,287,675; 4,364,188; 4,364,189; 4,297,797; 4,445,283; and 5,247,742.
In addition to the control of pronation, another type of foot motion in athletics also places “stabilization” demands on athletic footwear. This type of motion is lateral, sideways or cutting movements which frequently happen in sports like basketball, volleyball, football, soccer and the like. An athlete in such athletics may be required to perform a variety of motions including movement to the side; quickly executed direction changes, stops, and starts; movement in a backwards direction; and jumping. While making such movements, footwear instability may lead to excessive inversion or eversion of the ankle joint, otherwise known as ankle sprain. For example, an athlete may be required to perform a rapid, lateral movement on a surface with friction characteristics that prevent sliding of the sole relative to the surface. Upon contact with the surface, the lateral portion of the foot impacts the interior of the footwear causing the lateral side of the midsole to compress substantially more than the medial side. The downward incline on the interior of the footwear caused by the differential compression, in conjunction with the momentum of the athlete's body, creates a situation wherein the shoe rolls towards the lateral side, causing an ankle sprain. Similar situations which cause excessive inversion or eversion comprise one of the most common types of injury associated with athletic activities. A shoe with high lateral (side-to-side) stability will minimize the effects of differential compression by returning to a condition of equilibrium—tending to center the foot over the sole.
The preceding example particularly arises when footwear incorporates a midsole with cushioning qualities that sacrifice stability. In order to compensate for this lack of stability, designers often incorporate devices into the upper that increase stiffness. These devices attempt to provide a stable upper to compensate for an instable sole. Such devices take the form of rigid members, elastic materials, or straps that add to the overall weight of the footwear, make the article of footwear cumbersome, or restrict plantar flexion and dorsi flexion. For example, U.S. Pat. No. 4,989,350 to Bunch et al. discloses an article of footwear with sheet springs attached to the ankle portion, and U.S. Pat. No. 5,152,082 to Culpepper discloses an ankle support including a plurality of stiff projections extending along the heel and ankle. U.S. Pat. No. 5,896,683 to Foxen et al. discloses a support in the form of a plurality of finger-like elements attached to the upper which does not add significant weight to the shoe and allows plantar and dorsi flexion.
U.S. Pat. No. 5,343,639 to Kilgore et al., which is hereby incorporated by reference, discloses an athletic shoe wherein a portion of the foam midsole is replaced with foam columns placed between a rigid upper and lower plate.
FIGS. 1 and 2
depict this prior art shoe. As seen in
FIG. 1
, four support elements are incorporated in the midsole. Shoe
10
includes conventional upper
12
attached in a conventional manner to sole
14
. Sole
14
includes midsole
18
, and conventional outsole layer
20
formed of a conventional wear-resistant material such as a carbon-black rubber compound. Midsole
18
includes footframe
23
, cushioning and stability component
24
, midfoot wedge
40
and cushioning layer
22
made of a conventional cushioning material such as ethyl vinyl acetate (E.V.A.) or conventional non-microcellular polyurethane (PU) foam extending substantially throughout at least the forefoot portion of shoe
10
.
Midsole
18
includes cushioning and stability component
24
extending rearwardly approximately from the forefoot to a location adjacent the posterior portion of cushioning layer
22
. Cushioning and stability component
24
includes shell or envelope
26
having upper and lower plates
28
and
30
, defining therebetween an open area of the sole, and a plurality of compliant elastomeric support elements
32
disposed in the open area. In a preferred embodiment of this prior art shoe, elements
32
have the shape of hollow, cylindrical columns or columns containing a plurality of interior voids. Furthermore, the columns of the prior art have flat upper surfaces, the upper surfaces being parallel with the outsole.
Shell
26
may be made from nylon or other suitable materials such as BP8929-2 RITEFLEX™, a polyester elastomer manufactured by Hoechst-Celanese of Chatham, N.J., or a combination of nylon having glass mixed therewith, for example, nylon with 13% glass. Other suitable materials would include materials having a moderate flexural modulus and exhibiting high resistance to flexural fatigue. Support elements
32
are made from a material comprising a microcellular polyurethane, for example, a microcellular polyurethane-elastomer based on a polyester-alcohol and naphthalene-1,5-diisocyanate (NDI), such as the elastomeric foam material manufactured and sold under the name ELASTOCELL™ by BASF Corporation. Other suitable polyurethane materials such as a microcellular polyurethane-elastomer based on a polyester-alcohol and methylenediphenylene-4,4′-diisocyanate (MDI) and a microcellular polyu
Avar Eric P.
Foxen Thomas
Santos Craig E.
Banner & Witcoff , Ltd.
Nike Inc.
Patterson M. D.
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