U.S. patent application number 09/993665 was filed with the patent office on 2002-06-20 for corrective shoe sole structures using a contour greater than the theoretically ideal stability plane.
This patent application is currently assigned to Anatomic Research, Inc.. Invention is credited to Ellis, Frampton E. III.
Application Number | 20020073578 09/993665 |
Document ID | / |
Family ID | 23650142 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020073578 |
Kind Code |
A1 |
Ellis, Frampton E. III |
June 20, 2002 |
Corrective shoe sole structures using a contour greater than the
theoretically ideal stability plane
Abstract
A shoe having a sole contour which follows a theoretically ideal
stability plane as a basic concept, but which deviates outwardly
therefrom to provide greater than natural stability. Thickness
variations outwardly from the stability plane are disclosed, along
with density variations to achieve a similar greater than natural
stability.
Inventors: |
Ellis, Frampton E. III;
(Arlington, VA) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT &
DUNNER LLP
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
Anatomic Research, Inc.
|
Family ID: |
23650142 |
Appl. No.: |
09/993665 |
Filed: |
November 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09993665 |
Nov 27, 2001 |
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08452490 |
May 30, 1995 |
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08452490 |
May 30, 1995 |
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08142120 |
Oct 28, 1993 |
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08142120 |
Oct 28, 1993 |
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07830747 |
Feb 7, 1992 |
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07830747 |
Feb 7, 1992 |
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07416478 |
Oct 3, 1989 |
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Current U.S.
Class: |
36/25R |
Current CPC
Class: |
A43B 13/143 20130101;
A43B 13/18 20130101; A43B 13/12 20130101; A43B 13/146 20130101;
A43B 13/145 20130101; A43B 5/00 20130101 |
Class at
Publication: |
36/25.00R |
International
Class: |
A43B 013/00 |
Claims
What is claimed is:
1. A shoe construction for a shoe, comprising: a sole having a
naturally contoured shape defined by a design which conforms to the
natural shape of the unloaded foot wherein the theoretically ideal
stability plane is determined by the desired shoe sole thickness
and by the natural shape of a foot surface of the individual, said
theoretically ideal stability plane being defined at an edge of the
shoe by the desired shoe sole thickness in a frontal plane cross
section, said shoe sole thickness increasing beyond the
theoretically ideal stability plane to increase stability beyond
its natural level.
2. The shoe sole construction as set forth in claim 1 wherein the
thickness of the sole at least at one of the opposed edges of said
sole is thicker at the portions of the sole by a thickness which
gradually varies continuously from a first thickness through at
least an additional thickness.
3. The shoe sole construction as set forth in claim 1 wherein the
thickness of the sole gradually varies so that at least a portion
of said sole has a thickness which is greater than the thickness
predicted by the theoretically ideal stability plane.
4. The shoe sole construction as set forth in claim 1 wherein the
shoe sole is made from a material or materials which deform when
the shoe is worn thus naturally closely paralleling the natural
deformation of the bare foot under load.
5. The shoe sole construction as set forth in claim 1 wherein the
shoe sole thickness varies in a frontal plane cross section.
6. The shoe sole construction as set forth in claim 1, wherein said
shoe sole thickness increases beyond the theoretically ideal
stability plane in order to provide greater than natural
stability.
7. The shoe sole construction as set forth in claim 1, wherein said
shoe sole thickness increases beyond the theoretically ideal
stability plane in such a manner that there are proportionately
equal increases to the theoretically ideal stability plane from the
front of the shoe sole to its back.
8. The shoe sole construction as set forth in claim l wherein said
shoe sole thickness increases beyond the theoretically ideal
stability plans in such a manner that the thickness varies from one
frontal plane cross section to another.
9. The shoe sole construction as set forth in claim 2 wherein
variations in the increased thickness of the sole are determined
empirically.
10. The shoe sole construction as set forth in claim 2 wherein said
thickness variations are symmetrical as between lateral and medial
sides of said shoe.
11. The shoe sole construction as set forth in claim 2 wherein said
thickness s variations are asymmetrical as between lateral and
medial sides of said shoe.
12. The shoe sole construction as set forth in claim 2 wherein said
thickness variations begin beneath the heel of the wearer.
13. The shoe sole construction as set forth in claim 2 wherein said
thickness variations begin at a point beneath the heel of the
wearer, so that the theoretical ideal stability plane is determined
by the least thickness in the load-bearing portion of the shoe
sole.
14. The shoe sole construction as set forth in claim 2 wherein said
thickness variations increase then decrease along said outer sole
contour in a frontal plane cross section.
15. A shoe sole construction for a shoe, comprising: a sole having
a naturally contoured shape defined by a design which conforms to
the natural shape of the unloaded foot wherein the theoretically
ideal stability plane is determined by the desired shoe sole
thickens which is normally constant in a frontal plane cross
section, said sole including a midsole having a density variation
to approximate a greater than natural stability, said midsole
having material of greater density nearer to the edge of the shoe
sole and material of lesser density nearer to the center line of
the shoe sole.
16. The shoe as set forth in claim 15 wherein material of least
density is located beneath the heel of a wearer and material of
greater density is located adjacent said material of least
density.
17. The shoe as set forth in claim 15 wherein said sole has a
portion which extends beyond the theoretically ideal stability
plane.
18. The shoe as set forth in claim 15 wherein said density
variation is provided by variations in the bottom sole tread.
19. A shoe construction comprising, a shoe sole having opposed
stability quadrant portions at opposed edges of said sole, said
quadrants portions having an outer edge which is defined by a
radius quarter than a radius defining a theoretically ideal
stability plane.
20. A shoe construction for a shoe, comprising: a sole having a
naturally contoured shape defined by a design which conforms to the
natural shape of the unloaded foot wherein the theoretically ideal
stability plane is determined by the desired shoe sole thickness
and by the natural shape of a foot surface of the individual, said
theoretically ideal stability plane being defined at an edge of the
shoe by the desired shoe sole thickness in a frontal plane cross
section, said shoe sole thickness decreasing from the theoretically
ideal stability plane to increase foot motion beyond its natural
level.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to the structure of shoes.
More specifically, this invention relates to the structure of
running shoes. Still more particularly, this invention relates to
variations in the structure of such shoes having a sole contour
which follows a theoretically ideal stability plane as a basic
concept, but which deviates therefrom outwardly, to provide greater
than natural stability. Still more particularly, this invention
relates to the use of structures approximating, but increasing
beyond, a theoretically ideal stability plane to provide greater
than natural stability for an individual whose natural foot and
ankle biomechanical functioning have been degraded by a lifetime
use of flawed existing shoes.
[0002] Existing running shoes are unnecessarily unsafe. They
seriously disrupt natural human biomechanics. The resulting
unnatural foot and ankle motion leads to what are abnormally high
levels of running injuries.
[0003] Proof of the unnatural effect of shoes has come quite
unexpectedly frog the discovery that, at the extreme end of its
normal range of motion, the unshod bare foot is naturally stable,
almost unsprainable, while the foot equipped with any shoe,
athletic or otherwise, is artificially unstable and abnormally
prone to ankle sprains. Consequently, ordinary ankle sprains must
be viewed as largely an unnatural phenomena, even though fairly
common. Compelling evidence demonstrates that the stability of bare
feet is entirely different from the stability of shoe-equipped
feet.
[0004] The underlying cause of the universal instability of shoes
is a critical but correctable design flaw. That hidden flaw, so
deeply ingrained in existing shoe designs, is so extraordinarily
fundamental that it has remained unnoticed until now. The flaw is
revealed by a novel new biomechanical test, one that is
unprecedented in its simplicity. The test simulates a lateral ankle
sprain while standing stationary. It is easy enough to be a
duplicated and verified by anyone; it only takes a few minutes and
requires no scientific equipment or expertise.
[0005] The simplicity of the test belies its surprisingly
convincing results. It demonstrates an obvious difference in
stability between a bare foot and a running shoe, a difference so
unexpectedly huge that it makes an apparently subjective test
clearly objective instead. The test proves beyond doubt that all
existing shoes are unsafely unstable.
[0006] The broader implications of this uniquely unambiguous
discovery are potentially far-reaching. The same fundamental flaw
in existing shoes that is glaringly exposed by the new test also
appears to be the major cause of chronic overuse injuries, which
are unusually common in running, as well as other sport injuries.
It causes the chronic injuries in the same way it causes ankle
sprains; that is, by seriously disrupting natural foot and ankle
biomechanics.
[0007] The applicant has introduced into the art the concept of a
theoretically ideal stability plane as a structural basis for shoe
sole designs. That concept as implemented into shoes such as
street-shoes and athletic shoes is presented in pending U.S.
applications Ser. No. 07/219,387, filed on Jul. 15, 1985;
07/239,667, filed on Sep. 2, 1988; and 07/400,714, filed an Aug.
30, 1989, as well as in PCT Application No. PCT/US89/03076 filed on
Jul. 14, 1989. The purpose of the theoretically ideal stability
plane as described in these applications was primarily to provide a
neutral design that allows for natural foot and ankle biomechanics
as close as possible to that between the foot and the ground, and
to avoid the serious interference with natural foot and ankle
biomechanics inherent in existing shoes.
[0008] This new invention is a modification of the inventions
disclosed and claimed in the earlier application and develops the
application of the concept of the theoretically ideal stability
plane to other shoe structures. As such, it presents certain
structural ideas which deviate outwardly from the theoretically
ideal stability plane to compensate for faulty foot biomechanics
caused by the major flaw in existing shoe designs identified in the
earlier patent applications.
[0009] The shoe sole designs in this application are based on a
recognition that lifetime use of existing shoes, the unnatural
design of which is innately and seriously flawed, has produced
actual structural changes in the human foot and ankle. Existing
shoes thereby have altered natural human biomechanics in many, if
not most, individuals to an extent that must be compensated for in
an enhanced and therapeutic design. The continual repetition of
serious interference by existing shoes appears to have produced
individual biomechanical changes that may be permanent,so simply
removing the cause is not enough. Treating the residual effect must
also be undertaken.
[0010] Accordingly, it is a general object of this invention to
elaborate upon the application of the principle of the
theoretically ideal stability plane to other shoe structures.
[0011] It is still another object of this invention to provide a
shoe having a sole contour which deviates outwardly in a
constructive way from the theoretically ideal stability plane.
[0012] It is another object of this invention to provide a sole
contour having a shape naturally contoured to the shape of a human
foot, but having a shoe sole thickness which is increases somewhat
beyond the thickness specified by the theoretically ideal stability
plane.
[0013] It is another object of this invention to provide a
naturally contoured shoe sole having a thickness somewhat greater
than mandated by the concept of a theoretically ideal stability
plane, either through most of the contour of the sole, or a
preselected portions of the sole.
[0014] It is yet another object of this invention to provide a
naturally contoured shoe sole having a thickness which approximates
a theoretically ideal stability plane, but which varies toward
either a greater thickness throughout the sole or at spaced
portions thereof, or toward a similar but lesser thickness.
[0015] These and other objects of the invention will become
apparent from a detailed description of the invention which follows
taken with the accompanying drawings.
BRIEF DESCRIPTION OF THE INVENTION
[0016] Directed to achieving the aforementioned objects and to
overcoming problem with prior art shoes, a shoe according to the
invention comprises a sole having at least a portion thereof
following approximately the contour of a theoretically ideal
stability plane, preferably applied to a naturally contoured shoe
sole approximating the contour of a human foot.
[0017] In another aspect, the shoe includes a naturally contoured
sole structure exhibiting natural deformation which closely
parallels the natural deformation of a foot under the same load,
and having a contour which approximates, but increases beyond the
theoretically ideal stability plane. When the shoe sole thickness
is increased beyond the theoretically ideal stability plane,
greater than natural stability results; when thickness is
decreased, greater than natural motion results.
[0018] In a preferred embodiment, such variations are consistent
through all frontal plane cross sections so that there are
proportionally equal increases to the theoretically ideal stability
plane from front to back. In alternative embodiments, the thickness
may increase, then decrease at respective adjacent locations, or
vary in other thickness sequences.
[0019] The thickness variations may be symmetrical on both sides,
or asymmetrical, particularly since it may be desirable to provide
greater stability for the medial side than the lateral side to
compensate for common pronation problems. The variation pattern of
the right shoe can vary from that of the left shoe. Variation in
shoe sole density or bottom sole tread can also provide reduced but
similar effects.
[0020] These and other features of the invention will become
apparent from the detailed description of the invention which
follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows, in frontal plane cross section at the heel
portion of a shoe, the applicant's prior invention of a shoe sole
with naturally contoured sides based on a theoretically ideal
stability plane.
[0022] FIG. 2 shows, again in frontal plane cross section, the lost
general case of the applicant's prior invention, a fully contoured
shoe sole that follows the natural contour of the bottom of the
foot as well as its sides, also based on the theoretically ideal
stability plane.
[0023] FIG. 3, as seen in FIGS. 3A to 3C in frontal plane cross
section at the heel, shows the applicant's prior invention for
conventional shoes, a quadrant-sided shoe sole, based on a
theoretically ideal stability plane.
[0024] FIG. 4 shows a frontal plane cross section at the heel
portion of a shoe with naturally contoured sides like those of FIG.
1, wherein a portion of the shoe sole thickness is increased beyond
the theoretically ideal stability plane.
[0025] Fig, 5 is a view similar to FIG. 4, but of a shoe with fully
contoured sides wherein the sole thickness increases with
increasing distance from the center line of the ground-engaging
portion of the sole.
[0026] FIG. 6 is a view similar to FIG. 5 where the fully contoured
sole thickness variations are continually increasing on each
side.
[0027] FIG. 7 is a view similar to FIGS. 4 to 6 wherein the sole
thicknesses vary in diverse sequences.
[0028] FIG. 8 is a frontal plane cross section showing a density
variation in the midsole.
[0029] FIG. 9 is a view similar to FIG. 8 wherein the firmest
density material is at the outermost edge of the midsole
contour.
[0030] FIG. 10 is a view similar to FIGS. 8 and 9 showing still
another density variation, one which is asymetrical.
[0031] FIG. 11 shows a variation in the thickness of the sole for
the quadrant embodiment which is greater than a theoretically ideal
stability plane.
[0032] FIG. 12 shows a quadrant embodiment as in FIG. 11 wherein
the density of the sole varies.
[0033] FIG. 13 shows a bottom sole tread design that provides a
similar density variation as that in FIG. 10.
[0034] FIG. 14 shows embodiments like FIGS. 1 through 3 but wherein
a portion of the shoe sole thickness is decreased to less than the
theoretically ideal stability plane.
[0035] FIG. 15 show embodiments with sides both greater and lesser
than the theoretically ideal stability plane.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] FIGS. 1, 2, and 3 show frontal plane cross sectional views
of a shoe sole according to the applicant's prior inventions based
on the theoretically ideal stability plane, taken at about the
ankle joint to show the heal section of the shoe. FIGS. 4 through
13 show the same view of the applicant's enhancement of that
invention. The reference numerals are like those used in the prior
pending applications of the applicant mentioned above and which are
incorporated by reference for the sake of completeness of
disclosure, if necessary. In the figures, a foot 27 is positioned
in a naturally contoured shoe having an upper 21 and a sole 28. The
shoe sole normally contacts the ground 43 at about the lower
central heel portion thereof, as shown in FIG. 4. The concept of
the theoretically ideal stability plane, as developed in the prior
applications as noted, defines the plane 51 in terms of a locus of
points determined by the thickness (a) of the sole.
[0037] FIG. 1 shows, in a rear cross sectional view, the
application of the prior invention showing the inner surface of the
shoe sole conforming to the natural contour of the foot and the
thickness of the shoe sole remaining constant in the frontal plane,
so that the outer surface coincides with the theoretically ideal
stability plane.
[0038] FIG. 2 shows a fully contoured shoe sole design of the
applicant's prior invention that follows the natural contour of all
of the foot, the bottom an well as the sides, while retaining a
constant shoe sole thickness in the frontal plane.
[0039] The fully contoured shoe sole assumes that the resulting
slightly rounded bottom when unloaded will deform under load and
flatten just as the human foot bottom is slightly rounded unloaded
but flattens under load, therefore, shoe sole material must be of
such composition as to allow the natural deformation following that
of the foot. The design applies particularly to the heel, but to
the rest of the shoe sole as well. By providing the closest match
to the natural shape of the foot, the fully contoured design allows
the foot to function as naturally as possible. Under load, FIG. 2
would deform by flattening to look essentially like FIG. 1. Seen in
this light, the naturally contoured side design in FIG. 1 is a more
conventional, conservative design that is a special case of the
more general fully contoured design in FIG. 2, which is the closest
to the natural form of the foot, but the least conventional. The
amount of deformation flattening used in the FIG. 1 design, which
obviously varies under different loads, is not an essential element
of the applicant's invention.
[0040] FIGS. 1 and 2 both show in frontal plane cross sections the
essential concept underlying this invention, the theoretically
ideal stability plane, which is also theoretically ideal for
efficient natural motion of all kinds, including running, jogging
or walking. FIG. 2 shows the most general case of the invention,
the fully contoured design, which conforms to the natural shape of
the unloaded foot. For any given individual, the theoretically
ideal stability plane 51 is determined, first, by the desired shoe
sole thickness (s) in a frontal plane cross section, and, second,
by the natural shape of the individuals foot surface 29.
[0041] For the special case shown in FIG. 1, the theoretically
ideal stability plane for any particular individual (or size
average of individuals) is determined, first, by the given frontal
plane cross section shoe sole thickness (s); second, by the natural
shape of the individuals foot; and, third, by the frontal plane
cross section width of the individual's load-bearing footprint 30b,
which is defined as the upper surface of the shoe sole that is in
physical contact with and supports the human foot sole.
[0042] The theoretically ideal stability plane for the special case
is composed conceptually of two parts. Shown in FIG. 1, the first
part is a line savant 31b of equal length and parallel to line 30b
at a constant distance (s) equal to shoe sole thickness. This
corresponds to a conventional shoe sole directly underneath the
human foot, and also corresponds to the flattened portion of the
bottom of the load-bearing foot sole 28b. The second part is the
naturally contoured stability side outer edge 31a located at each
side of the first part, line segment 31b. Each point on the
contoured side outer edge 31a is located at a distance which is
exactly shoe sole thickness (s) from the closest point on the
contoured side inner edge 30a.
[0043] In summary, the theoretically ideal stability plane is the
essence of this invention because it is used to determine a
geometrically precise bottom contour of the shoe sole based on a
top contour that conforms to the contour of the foot. This
invention specifically claims the exactly determined geometric
relationship just described.
[0044] It can be stated unequivocally that any shoe sole contour,
even of similar contour, that exceeds the theoretically ideal
stability plane will restrict natural foot motion, while any less
than that plane will degrade natural stability, in direct
proportion to the amount of the deviation. The theoretical ideal
was taken to be that which is closest to natural.
[0045] FIG. 3 illustrates in frontal plane cross section another
variation of the applicant's prior invention that uses stabilizing
quadrants 26 at the outer edge of a conventional shoe sole 28b
illustrated generally at the reference numeral 28. The stabilizing
quadrants would be abbreviated in actual embodiments.
[0046] FIG. 4 illustrates the applicant's new invention of shoe
sole side thickness increasing beyond the theoretically ideal
stability plane to increase stability somewhat beyond its natural
level. The unavoidable trade-off resulting is that natural notion
would be restricted somewhat and the weight of the shoe sole would
increase somewhat.
[0047] FIG. 4 shows a situation wherein the thickness of the sole
at each of the opposed sides is thicker at the portions of the sole
31a by a thickness which gradually varies continuously from a
thickness (s) through a thickness (s+s1), to a thickness
(s+s2).
[0048] These designs recognize that lifetime use of existing shoes,
the design of which has an inherent flaw that continually disrupts
natural human biomechanics, has produced thereby actual structural
changes in a human foot and ankle to an extent that must be
compensated for. Specifically, one of the most common of the
abnormal effects of the inherent existing flaw is a weakening of
the long arch of the foot, increasing pronation. These designs
therefore modify the applicant's preceding designs to provide
greater than natural stability and should be particularly useful to
individuals, generally with low arches, prone to pronate
excessively, and could be used only on the medial side. Similarly,
individuals with high arches and a tendency to over supinate and
lateral ankle sprains would also benefit, and the design could be
used only on the lateral side. A shoe for the general population
that compensates for both weaknesses in the same shoe would
incorporate the enhanced stability of the design compensation on
both sides.
[0049] The new design in FIG. 4, like FIGS. 1 and 2, allows the
shoe sole to deform naturally closely paralleling the natural
deformation of the barefoot underload; in addition, shoe sole
material must be of such composition as to allow the natural
deformation following that of the foot.
[0050] The new designs retain the essential novel aspect of the
earlier designs; namely, contouring the shape of the shoe sole to
the shape of the human foot. The difference is that the shoe sole
thickness in the frontal plane is allowed to vary rather than
remain uniformly constant. More specifically, FIGS. 4, 5, 6, 7, and
11 show, in frontal plane cross sections at the heel, that the shoe
sole thickness can increase beyond the theoretically ideal
stability plane 51, in order to provide greater than natural
stability. Such variations (and the following variations) can be
consistent through all frontal plane cross sections, so that there
are proportionately equal increases to the theoretically ideal
stability plane 51 from the front of the shoe sole to the back, or
that the thickness can vary, preferably continuously, from one
frontal plane to the next.
[0051] The exact amount of the increase in shoe sole thickness
beyond the theoretically ideal stability plane is to be determined
empirically. Ideally, right and left shoe soles would be custom
designed for each individual based on an biomechanical analysis of
the extent of his or her foot and ankle disfunction in order to
provide an optimal individual correction. If epidemiological
studies indicate general corrective patterns for specific
categories of individuals or the population as a whole, then
mass-produced corrective shoes with soles incorporating contoured
sides exceeding the theoretically ideal stability plane would be
possible. It is expected that any such mass-produced corrective
shoes for the general population would have thicknesses exceeding
the theoretically ideal stability plane by an amount up to 5 or 10
percent, while more specific groups or individuals with more severe
disfunction could have an empirically demonstrated need for greater
corrective thicknesses on the order of up to 25 percent more than
the theoretically ideal stability plane. The optimal contour for
the increased thickness may also be determined empirically.
[0052] FIG. 5 shows a variation of the enhanced fully contoured
design wherein the shoe sole begins to thicken beyond the
theoretically ideal stability plane 51 somewhat offset to the
sides.
[0053] FIG. 6 shows a thickness variation which is symmetrical as
in the case of FIGS. 4 and 5, but wherein the shoe sole begins to
thicken beyond the theoretically ideal stability plane 51 directly
underneath the foot heel 27 on about a center line of the shoe
sole. In fact, in this case the thickness of the shoe sole is the
same as the theoretically ideal stability plane only at that
beginning point underneath the upright foot. For the applicant's
new invention where the shoe sole thickness varies, the
theoretically ideal stability plane is determined by the least
thickness in the shoe sole's direct load-bearing portion meaning
that portion with direct tread contact on the ground; the outer
edge or periphery of the shoe sole is obviously excluded, since the
thickness there always decreases to zero. Note that the capability
to deform naturally of the applicant's design may make some
portions of the shoe sole load-bearing when they are actually under
a load, especially walking or running, even though they might not
appear to be when not under a load.
[0054] FIG. 7 shows that the thickness can also increase and then
decrease; other thickness variation sequences are also possible.
The variation in side contour thickness in the new invention can is
be either symmetrical on both sides or asymmetrical, particularly
with the medial side providing more stability than the lateral
side, although many other asymmetrical variations are possible, and
the pattern of the right foot can vary from that of the left
foot.
[0055] FIGS. 8, 9, 10 and 12 show that similar variations in shoe
midsole (other portions of the shoe sole area not shown) density
can provide similar but reduced effects to the variations in shoe
sole thickness described previously in FIGS. 4 through 7. The major
advantage of this approach is that the structural theoretically
ideal stability plane is retained, so that naturally optimal
stability and efficient motion are retained to the maximum extent
possible.
[0056] The forms of dual and tri-density midsoles shown in the
figures are extremely common in the current art of running shoes,
and any number of densities are theoretically possible, although an
angled alternation of just two densities like that shown in FIG. 8
provides continually changing composite density. However, the
applicant's prior invention did not prefer multi-densities in the
midsole, since only a uniform density provides a neutral shoe sole
design that does not interfere with natural foot and ankle
biomechanics in the way that multi-density shoe soles do, which is
by providing different amounts of support to different parts of the
foot; it did not, of course, preclude such multi-density midsoles.
In these figures, the density of the sole material designated by
the legend (d1) is firmer than (d) while (d2) is the firmest of the
a three representative densities shown. In FIG. 8, a dual density
sole is shown, with (d) having the less firm density.
[0057] It should be noted that shoe soles using a combination both
of sole thicknesses greater than the theoretically ideal stability
plane and of midsole densities variations like those just described
are also possible but not shown.
[0058] FIG. 13 shows a bottom sole tread design that provides about
the same overall shoe sole density variation as that provided in
FIG. 10 by midsole density variation. The less supporting tread
there is under any particular portion of the shoe sole, the less
effective overall shoe sole density there is, since the midsole
above that portion will deform more easily that if it were fully
supported.
[0059] FIG. 14 shows embodiments like those in FIGS. 4 through 13
but wherein a portion of the shoe sole thickness is decreased to
less than the theoretically ideal stability plane. It is
anticipated that some individuals with foot and ankle biomechanics
that have been degraded by existing shoes may benefit from such
embodiments, which would provide less than natural stability but
greater freedom of motion, and less shoe sole weight add bulk. In
particular, it is anticipated that individuals with overly rigid
feet, those with restricted range of motion, and those tending to
over-supinate may benefit from the FIG. 14 embodiments. Even more
particularly, it is expected that the invention will benefit
individuals with significant bilateral foot function asymmetry:
namely, a tendency toward pronation on one foot and supination on
the other Soot. Consequently, it is anticipated that this
embodiment would be used only on the shoe sole of the supinating
foot, and on the inside portion only, possibly only a portion
thereof. It is expected that the range less than the theoretically
ideal stability plane would be a maximum of about five to ten
percent, though a maximum of up to twenty-five percent way be
beneficial to some individuals.
[0060] FIG. 14A shows an embodiment like FIGS. 4 and 7, but with
naturally contoured sides less than the theoretically ideal
stability plane. FIG. 14B shows an embodiment like the fully
contoured design in FIGS. 5 and 6, but with a shoe sole thickness
decreasing with increasing distance from the center portion of the
sole. FIG. 14C shows an embodiment like the quadrant-sided design
of FIG. 11, but with the quadrant sides increasingly reduced from
the theoretically ideal stability plane.
[0061] The lesser-sided design of FIG. 14 would also apply to the
FIGS. 8 through 10 and 12 density variation approach and to the
FIG. 13 approach using tread design to approximate density
variation.
[0062] FIG. 15 A-C show, in cross sections similar to those in
pending U.S. application Ser. No. 07/219,387, that with the
quadrant-sided design of FIGS. 3, 11, 12 and 14C that it is
possible to have shoe sole sides that are both greater and lesser
than the theoretically ideal stability plane in the same shoe. The
radius of an intermediate shoe sole thickness, taken at (S.sup.2)
at the base of the fifth metatarsal in FIG. 15B, is maintained
constant throughout the quadrant sides of the shoe sole, including
both the heel, FIG. 15C, and the forefoot, FIG. 15A, so that the
side thickness is less than the theoretically ideal stability plane
at the heel and more at the forefoot. Though possible, this is not
a preferred approach.
[0063] The same approach can be applied to the naturally contoured
sides or fully contoured designs described in FIGS. 1, 2, 4 through
10 and 13, but it is also not preferred. In addition, is shown in
FIGS. 15D-F, in cross sections similar to those in pending U.S.
application Ser. No. 07/239,667, it is possible to have shoe sole
sides that are both greater and lesser than the theoretically ideal
stability plane in the same shoe, like FIGS. 15A-C, but wherein the
side thickness (or radius) is neither constant like FIGS. 15A-C or
varying directly with shoe sole thickness, like in the applicant's
pending applications, but instead varying quite indirectly with
shoe sole thickness. As shown in FIGS. 15D-F, the shoe sole side
thickness varies from somewhat less than shoe sole thickness at the
heel to somewhat more at the forefoot. This approach, though
possible, is again not preferred, and can be applied to the
quadrant sided design, but is not preferred there either.
[0064] The foregoing shoe designs meet the objectives of this
invention as stated above. However, it will clearly be understood
by those skilled in the art that the foregoing description has been
made in terms of the preferred embodiments and various changes and
modifications may be made without departing from the scope of the
present invention which is to be defined by the appended
claims.
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