U.S. patent number 3,724,106 [Application Number 05/158,018] was granted by the patent office on 1973-04-03 for insole structure.
Invention is credited to Herbert Magidson.
United States Patent |
3,724,106 |
Magidson |
April 3, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
INSOLE STRUCTURE
Abstract
An insole structure for footwear comprised of upper and lower
surfaces which form one or more internal cavities within the body
of the structure, the cavities so formed containing a fluid such as
water, air or a gel, providing thereby a durable and comfortable
means for cushioning and supporting the feet inside footwear such
as shoes, sandals, slippers and/or boots. The present invention may
find embodiment in (i) a flexible contoured insole designed for
insertion into conventional footwear or (ii) in footwear having the
invented insole structure built into and made and integral part
thereof. The shape, location, height, etc., of the cavities can be
designed to achieve particular therapeutic objectives such as the
support of weak arches.
Inventors: |
Magidson; Herbert (Beverly
Hills, CA) |
Family
ID: |
22566360 |
Appl.
No.: |
05/158,018 |
Filed: |
June 29, 1971 |
Current U.S.
Class: |
36/44 |
Current CPC
Class: |
A43B
17/026 (20130101); A43B 17/03 (20130101) |
Current International
Class: |
A43B
17/02 (20060101); A43B 17/03 (20060101); A43B
17/00 (20060101); A43b 013/38 () |
Field of
Search: |
;36/44,29 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Guest; Alfred R.
Claims
I claim:
1. An insole adapted for insertion into a conventional article of
footwear comprising:
a. a single integral structure having an upper and a lower surface,
said lower surface having at least one raised region defining an
internal cavity between said upper and lower surfaces, said raised
region depending downwardly and having side walls lying at an angle
of approximately 45.degree. with reference to the vertical, said
structure being fabricated of a flexible non-porous plastic
selected from a group consisting of polyethylene, vinyl and
elastomeric plastic and having an overall thickness of
approximately 1/8 inch;
b. water disposed within said cavity and encapsulated therein at
ambient atmospheric pressure in a no-load condition; and
c. a moisture-absorbing fabric disposed upon and fixedly secured to
the top side of said upper surface, said fabric having a backing of
flexible plastic on its side which is in contact with said upper
surface, whereby, when said insole is inserted into said article of
footwear, it provides cushioning and support to the foot of a
wearer of said article, and said fabric absorbs moisture inside
said article.
2. The insole of claim 1 wherein said structure has a plurality of
perforations located in portions thereof displaced from said
internal cavity, said perforations being adapted to enable the
circulation of air through said structure.
3. In an article of footwear, and integral thereto, an insole
comprising:
a. a structure having an upper and a lower surface, said upper
surface having a first raised region defining a first internal
cavity between said upper and lower surfaces, said first raised
region being located and contoured upwardly to cooperatively engage
the arch of a human foot, said lower surface having at least one
raised region defining a second internal cavity between said
surfaces, said latter raised region depending downwardly and being
displaced from said first raised region in the longitudinal
direction of said structure, said structure being fabricated of a
flexible non-porous plastic selected from a group consisting of
polyethylene, vinyl and elastomeric plastic;
b. fluid of suitable viscosity disposed within said first and
second cavities and encapsulated therein, the pressure of said
fluid in said first cavity being sufficient to provide firm support
to said arch, the pressure of said fluid in said second cavity,
being ambient atmospheric pressure in a no-load condition; and
c. a moisture-absorbing fabric disposed upon and fixedly secured to
the top side of said upper surface, whereby said insole provides
cushioning and support to the foot of a wearer of said article of
footwear, and said fabric absorbs moisture inside said article.
4. In an article of footwear having an inner sole, an insole
providing cushioning and support to the foot of a wearer
comprising:
a. a plurality of suitably contoured cavities formed in the upper
region of said inner sole to a depth of approximately 1/8 inch,
said cavities being separated from one another by ribbed members
disposed thereinbetween, said cavities being adapted to contain
water therein;
b. a thin, substantially flat upper member made of a flexible
non-porous plastic selected from a group consisting of
polyethylene, vinyl and elastomeric plastic, said upper member
being disposed over and fixedly secured to said inner sole so as to
seal said cavities;
c. a moisture-absorbing fabric disposed upon and fixedly secured to
the top side of said upper member; and
d. water disposed within said cavities and encapsulated therein.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of footwear,
and more particularly to insoles and innersoles for foot cushioning
and/or supporting structures.
2. Prior Art
The use of insoles for enhancing the comfort of footwear is not
new. The prior art shows a number of such structures. One type of
insole disclosed by the prior art is the foamed rubber
thermoplastic insole designed to be inserted into the wearer's
footwear. This type of insole is typically comprised of a sheet of
cushioning material (e.g., foamed rubber) layered with one of a
pair of relatively thin outer sheets of suitable material. In
another structure of this type the cushioning material may be fully
enclosed within an outer structure. Regardless of their variations,
insoles of this type all suffer from the Same disadvantage, to wit:
the deterioration and/or compression of the cushioning material and
the resultant loss of resilience thereof. In some cases the
cushioning material may even desintegrate, rendering the insoles
useless as well as uncomfortable due to lumps and voids
therein.
Another type of prior art insole is the medicated insole having
encapsulated within an outer structure one or more medicating
materials such as (i) foot powder or (ii) rupturable plastic
capsules containing scented, cooling, germicidal and/Or fungicidal
substances. Insoles of this type typically have an upper section
made of a porous material in order to allow the powder or other
appropriate substance to pass through to the user's feet. These
insoles have the disadvantage of higher cost because of the
necessary inclusion therein of the consumable material. The prior
art discloses means for replenishing the supply of powder or other
consumable material in this type of insole. As a result, however,
the user must bear the cost of continual replacement of the
material in order to continue to use the insoles. On the other
hand, some of the structures disclosed by the prior art provide no
means for replenishing the consumable material. In these cases,
when the consumable is depleted, the entire insole becomes useless
and must be replaced.
A further disadvantage of medicated insoles is they provide little
cushioning of the feet. This is because they are conceived and
designed primarily as dispensers of powder or other medicated
substances and not as foot cushioners. In the first place, powders
and small plastic capsules have little resilience; secondly,
because of internal shear forces, powder and plastic capsules
cannot rapidly and uniformly distribute the pressure applied by the
weight of the user. As a result, insoles of this type lack good
cushioning characteristics.
The present invention overcomes these shortcomings of the prior art
by disclosing a novel structure which utilizes a fluid, such as,
for example, water, as the cushioning medium encapsulated within
one or more cavities within the body of the structure. Unlike the
prior art insoles which use foamed rubber or foamed thermoplastic
material, the fluid used in the present invention does not
deteriorate or compress under the temperature, pressure, and
Moisture conditions to which insoles are subjected. In addition,
unlike the medicated insoles, the Present invention does not
utilize or rely upon relatively expensive and consumable materials
in order to have a comforting effect upon the feet. And, further,
the use of a fluid as the cushioning medium results in a more
comfortable insole than that which is possible when powder or small
plastic capsules are used. This result is attributable to the well
knoWn physical property Of fluids under pressure, to wit: the
property of distributing the applied pressure uniformly and almost
instantly throughout the fluid. Thus, the encapsulated fluid
immediately redistributes itself within its cavities so that (i)
the upper section of the insole conforms to the contour of the
bottom surface of the user's foot where these surfaces are in
contact; and (ii) the supporting force provided by the fluid is
applied uniformly over the contacting surface of the user's foot.
As a result of this property of fluids, the present invention
provides a highly comfortable sensation to the user, a sensation
which has heretofore not been achievable.
SUMMARY OF THE INVENTION
The present invention is a novel insole structure which cushions
and supports the user's feet during the wearing of footwear such as
shoes, sandals, an integral and/or boots. The present invention
insole can either be an integral part of the item of footwear or a
separate structure designed for insertion into footwear.
The present invention is comprised of upper and lower contoured
surfaces which together form one or more internal cavities within
the body or the structure. The cavities so formed contain a
suitable fluid, such as water, which serves as the cushioning and
supporting medium of the insole. The fluid within the cavities is
entrapped; since it is normally unable to escape, the fluid lasts
for the life of the insole structure. The fluid filled cavities can
be located so as to provide support to particular portions of the
foot.
The invention insole structure achieves its unique cushioning and
supporting effect by utilizing the well known property of fluids;
i.e., the property of distributing applied pressure uniformly and
almost instantly throughout the fluid. Thus, when the user's weight
is applied to the invented structure the fluid in the cavities
immediately redistributes itself therein causing the upper surface
of the insole to conform to the bottom contour of the user's foot
where these surfaces are in contact, while, at the same time,
supporting the foot with uniform pressure over its contacting
surface. The effect is a pleasantly cushioned but firm sensation of
comfort While wearing footwear.
The benefits of the present invention are not limited to providing
comfort to wearer's of footwear. The invented insole structure can
also have a therapeutic effect upon feet which are not healthy in
one or more respects. The shape, location, contour and height of
the cavities, and the elasticity of the insole material can be
selected so as to provide the degree of cushioning and support
which is desired to those portions of the foot where it is needed.
For example, the invented insole can readily be configured to
provide support to weak arches.
In practicing the present invention embodiments thereof can be
either structurally independent of the item of footwear or an
integral part of it. In the former case the invented insole is
contoured to be inserted into and to fit properly in a
corresponding sized shoe, slipper, etc.
Embodiments of the present invention which are structurally
independent of the footwear are comprised of relatively thin upper
and lower contoured surfaces made of a flexible non-porous
material, such as polyethylene, vinyl or elastomeric plastic. In
some embodiments of this type, the upper surface is flat and has an
outer contour which conforms to the contour and style of the
footwear into which it is to be inserted. The lower surface also
has an outer contour conforming to that of the footwear. However,
the lower surface is not flat, but configured to provide one or
more raised (three-dimensional) regions. It is the raised regions
of the lower surface which in combination with the upper surface,
form the internal cavities of the invented insole structure. In
other structurally independent embodiments of the present invention
the lower surface is flat while the upper surface provides one or
more raised regions which, together with the lower surface, form
the internal cavities. One application of the latter embodiment
would be found in an insole structure configured to provide support
to the arch of the foot.
The present invention also contemplates structurally independent
embodiments which can be characterized as partial insoles; i.e.,
insoles configured to cushion and support only one portion of the
wearer's foot such as the heel, arch, or ball. Typically such
partial insoles have a single fluid-filled cavity and an outer
contour which conforms to the portion of the foot for which they
are adapted.
Those embodiments of the present invention which are configured to
fit within an item of conventional footwear must necessarily be
relatively thin. A preferred overall thickness is about 1/8 inch;
however, this constraint is not necessarily applicable in the
vicinity of the arch of the foot.
With respect to embodiments of the present invention which are
structurally part of the footwear, there are two which are
preferred. The first is comprised of upper and lower surfaces of a
flexible non-porous plastic, such as polyethylene, vinyl or
elastomeric plastic, each surface being cemented and/or sewn into
the structure of the item of footwear during the construction
process. The two surfaces form one or more cavities with the body
of the structure in which a suitable fluid is contained to provide
the desired cushioning and support. In a second preferred
embodiment of the type, the inner sole of the item of footwear is
utilized as the lower surface of the invented insole structure.
Accordingly, the inner sole has formed in its upper region one or
more compartments which, in combination with the upper surface,
form the fluid-containing cavities of the structure. The
compartments are typically located so that the cushioning and
support provided by the fluid is applied to one or more portions of
the foot as desired. The upper surface of the insole structure is
disposed on top of the inner sole of the item of footwear and
cemented and/or sewn therein, sealing the compartments in the inner
sole and thereby forming the inner cavities. The fluid contained in
these inner cavities provides the cushioning and support of the
user's foot which is characteristic of this invention. As in other
embodiments of the present invention, the upper surface is
typically a flat piece of flexible non-porous material such as
polyethylene vinyl or elastomeric plastic.
The user's foot interfaces with the top of the upper surface of the
structure. Consequently, in order to enhance the comfort of using
the invented insole, preferred embodiments include a
moisture-absorbing fabric or other suitable covering secured to the
top of the upper surface for the purpose of reducing the build-up
of a moisture during use.
The fluid which is encapsulated in the cavities within the body of
the structure is a suitable non-compressible fluid such as water,
air or a gel. The viscosity of the fluid is a variable, the
selection of which enables the designers to achieve a range of
effects relative to the "feel" of the insole. The cavities are
typically filled with the fluid up to the ambient barometric
pressure; i.e., without causing any stretching of the flexible
plastic material comprising the surfaces of the structure.
Stretching of this material does occur, however, when the user's
weight is applied to the insole, since there must be a
redistribution of the fluid within the cavities.
In some applications, such as where support of the arch is sought,
increased firmness may be required at a particular area of the
insole structure. To achieve greater firmness, the fluid in a
particular cavity can be maintained at a no-load pressure which is
greater than the ambient air pressure. As a result, the elastic
material comprising the structural surfaces will be stretched
somewhat, even under no-load conditions. When the user's weight is
applied to the insole, there will be less elasticity and,
consequently, greater firmness.
It can be seen therefore, that by selecting the viscosity of the
fluid, the pressure of the fluid in the cavities, and the
elasticity of the material comprising the surfaces of the
structure, the designer can achieve a broad range of support and
cushioning effects in practicing this invention. In addition, the
shape, contour, location and height of the cavities are variables
which, by appropriate selection, enable a wide range of design
objectives to be achieved.
Embodiments of the present invention can be made by plastic forming
and footwear construction techniques which are known in the art.
Plastic forming techniques suitable for making the flexible plastic
surfaces of the invented insole structure include injection
molding, vacuum molding and blow molding processes. Insertion of
the fluid into the cavities can be accomplished while the upper and
lower surfaces of the structure are being joined together, or
afterwards by appropriate injection and sealing techniques.
Thus, it is an object of the present invention to provide a
relatively inexpensive insole structure which comfortably cushions
and supports the user's feet when wearing footwear.
It is still another object of the present invention to provide an
insole structure which can be configured to have a therapeutic
effect upon the feet of the user.
It is still yet another object of the present invention to provide
a structure which is adapted for insertion into conventional
footwear.
A further object, of this invention is to provide a structure which
is built into and made an integral part of footwear.
Other objects novel features and advantages of the present
invention will become apparent upon making reference to the
following detailed description and the accompanying drawings. The
description and the drawings will also further disclose the
characteristics of this invention, both as to its structure and its
mode of operation. Although preferred embodiments of the invention
are described hereinbelow, and shown in the accompanying drawing,
it is expressly understood that the descriptions and drawings
thereof are for the purpose of illustration only and do not limit
the scope of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings in which are illustrated preferred
embodiments of the present invention:
FIG. 1 is a top perspective view of a first embodiment of the
present invention, showing an insole which is configured to be
inserted into conventional footwear.
FIG. 2 is a cross-sectional view of the insole structure of FIG. 1
taken along lines 2--2 of FIG. 1.
FIG. 3 is a cross-sectional view of the insole structure of FIG. 1
taken along lines 3--3 of FIG. 1.
FIG. 4 is a longitudinal cross-sectional view of another embodiment
of the present invention, showing a therapeutic shoe adapted to
support the wearer's arches.
FIG. 5 is a transverse cross-sectional view of the shoe of FIG. 4
taken along lines 5--5 of FIG. 4.
FIG. 6 is a longitudinal cross-sectional view of still another
embodiment of the present invention, showing a shoe having fluid
filled compartments in its inner sole.
FIG. 7 is a top perspective view of a further embodiment of the
present invention showing a single cavity insole partial insole
adapted to cushion and support the ball of the foot.
FIG. 8 is a top perspective view of another embodiment of the
present invention showing a single cavity partial insole adapted to
cushion and support the arch of the foot.
FIG. 9 is a top perspective view of a further embodiment of the
present invention showing a single cavity insole partial insole
adapted to cushion and support the heel of the foot.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to FIGS. 1-3 a first embodiment of the present
invention is described, generally designated by the reference
numeral 8. This first embodiment is an insole structure which is
adapted for insertion into an item of conventional footwear, such
as shoes, boots, slippers and/or sandals. It is comprised of an
upper surface 10 and a lower surface 12 made of a flexible,
non-porous polyethylene, vinyl or elastomeric plastic. In this
first embodiment 8, the upper surface 10 and lower surface 12 are
separate sections joined together by a suitable cement or other
means for joining plastic materials. However, it should be
understood that the present invention also contemplates embodiments
wherein the upper and lower surfaces 10 and 12 comprise a
continuous and integral structure. The upper surface 10 and the
lower surface 12 have outer contours which comform to the contour
and style of the footwear into which embodiment 8 is to be inserted
during use. Upper surface 10 is a flat piece of material, while
lower surface 12 has raised contoured regions 12a, 12b, 12c and
12d. When joined together surfaces 10 and 12 form cavities 14a -
14d in which a suitable non-compressible fluid 14' is contained
(FIG. 2). Thus, it is clear that in embodiments wherein surfaces 10
and 12 are separate members, their union must be such that a
suitable seal is formed. In embodiment 8, the fluid 14' contained
in cavities 14a - 14d provides cushioning and support to the
various portions of the foot, namely; the toes, ball, instep and
heel respectively. The present invention contemplates embodiments
having more or less than four cavities, as well as cavities at
different locations and of different shapes and contours. In
addition, this invention also contemplates embodiments having a
flat lower surface and a raised upper surface, the reverse of
embodiment 8, as well as embodiments whose upper and lower surfaces
each have raised regions. An embodiment of the latter type is
depicted in FIG. 4 and described more fully hereinbelow.
A suitable moisture-absorbing fabric covering 16, preferably
cotton, is disposed over the entire top of upper surface 10. Thus,
during use, the user's feet come into contact with covering 16
instead of the plastic material comprising upper surface 10.
Covering 16 absorbs the moisture normally generated in footwear and
thereby, enhances the comfort to be derived from use of the
invented insole. Covering 16 may be cemented to the top surface of
section 10 or joined by other suitable techniques known in the art.
FIGS. 2 and 3 depict the covering 16 cooperatively engaged by a lip
18 extending around the periphery of upper surface 10 and is
similar to that described in applicant's U.S. Pat. No. 3,599,353
issued on Aug. 17, 1971. Lip 18 is an integral part of upper
surface 10 and provides additional means for securing the covering
16 to the top of surface 10. Lip 18 will also prevent the edge of
covering 16 from fraying or otherwise becoming disengaged. The
extent to which the covering 16 is secured by the lip 18 is best
seen by reference to FIGS. 2 and 3. The preferred length of lip 18,
that is, the extent to which it overlaps covering 16, is about 1/32
inch. Although covering 16 can be any suitable moisture-absorbing
fabric, it is preferable that the fabric have a backing of flexible
plastic on the side interfacing with the top of upper surface 10.
Such backing would enhance the adhesion of covering 16 to surface
10.
Walls 13a, 13b, 13c, and 13d of raised regions 12a - 12d
respectively are configured at an angle, with reference to the
vertical, which ensures that they collapse under the weight of the
wearer's feet; i.e., by configuring the walls 13a - 13d at such an
angle, they are prevented from providing their own rigid structural
support. As the angle of the walls 13a - 13d approaches the
vertical, the walls 13a - 13d tend to act increasingly as rigid
support members. At the proper angle, typically in the region of
45.degree., the walls smoothly give way under the user's weight and
enable the insole support to be provided by the fluid 14'.
Since embodiment 8 is adapted for insertion into conventional
footwear, an overall thickness of about 1/18 of an inch is
preferred.
The fluid 14' can be water or other appropriate liquid, air or a
gel having a suitable viscosity. The fluid 14' is the cushioning
and supporting medium of the invented insole. When the weight of
the user's foot is applied to the upper section 10, fluid 14' in
the cavities 14a-14d immediately redistributes itself therein until
the upper surface 10 conforms to the contour of the bottom surface
of the user's foot whenever these surfaces are in contact. In
addition, since it is a property of fluids to distribute applied
pressure uniformily throughout the fluid, uniform support is
applied to the user's foot over its contacting surfaces. As a
result the user's weight is supported uniformly over a greater area
of his feet than is the case with non-fluid supporting means. Thus,
a firm, but pleasantly cushioned sensation of comfort is achieved
while wearing footwear.
The viscosity of fluid 14' and the elasticity of the plastic
material comprising surfaces 10 and 12 determine to a great extent
the "feel" of the invented insole; in addition, the no-load
pressure at which fluid 14' is maintained in cavities 14a - 14d is
a variable which has an effect upon the firmness, and therefore the
"feel," of the insole. As the no-load pressure of fluid 14'
increases above the ambient atmospheric pressure, the flexible
plastic material comprising surfaces 10 and 12 is stretched. To the
extent there is such non-load stretching, there is a corresponding
decrease in the ability of the material to stretch further when the
user's weight is applied to the insole. Consequently, the user's
weight is supported at a higher pressure applied over a smaller
area of his feet, resulting in a firmer feeling of support. In some
applications in which this invention may be practiced, greater
firmness at a particular portion of the insole is desirable, such
as where the insole is used to support the user's arches. Such an
application is more fully described hereinbelow with respect to a
second embodiment of the invention.
The benefits of the present invention are not limited to enhancing
the comfort of conventional footwear. The invention can be
practiced so as to provide a therapeutic benefit for certain foot
problems. For example, consider a user who has a sensitive area on
the sole of his foot due to a callous or a cut. Since the present
invention is better adapted than conventional insoles to uniformly
distribute the applied pressure over a larger area of the foot,
there is an immediate benefit to such a user by virtue of the fact
that less pressure is applied to the sensitive area. In addition,
an embodiment of the present invention can be designed which even
further reduces the pressure applied to the sensitive area. For
example, by providing a donut-shaped raised region on the upper
surface of the insole structure, a region coming into contact only
with the area of the user's sole surrounding the sensitive area,
the pressure on the sensitive area can be reduced
substantially.
Another therapeutic application of the present invention relates to
the support of weak arches. With reference to FIGS. 4 and 5, a
second embodiment, a therapeutic shoe 30 configured for use by
persons with weak arches, is described. In this embodiment the
insole structure is an integral part of the shoe 30 and is
incorporated therein during the process of shoe construction. The
insole structure is comprised of an upper surface 32, having a
raised contoured region 32c in the vicinity of the arch, and a
lower surface 34 having raised regions 34a, 34b, and 34d. Surface
34 is disposed upon the inner sole 35 and is secured thereto, as
well as to the structure of shoe 30, by conventional techniques
known in the art. Surfaces 32 and 34 are made of a flexible plastic
material such as those disclosed hereinabove. When joined, they
form cavities 36a - 36d which contain a fluid 36' in the same
manner as described above with reference to the embodiment shown in
FIG. 2. Of particular interest in this, second embodiment 30 is the
raised region 32c of surface 32 which forms cavity 36c. It is
shaped to conform to the normal contour of the arch of a human foot
and is located with respect thereto. The fluid 36' in cavity 36c is
preferably one having a high viscosity. The no-load pressure of
fluid 36' in cavity 36c and the elasticity of the plastic material
comprising surface 32 can be selected by those skilled in the art
so that the insole structure in the vicinity of the user's arch
provides firm support thereto.
A moisture-absorbing covering 38 is preferably disposed upon the
top of surface 32 and secured thereto, as well as to the structure
of shoe 30 by means known in the art.
The manner in which the insole structure of this second embodiment
30 provides cushioning and support to the user's feet is the same
as that described above with respect to the first embodiment. As is
the case with respect to the first preferred embodiment described
hereinabove, walls 37a, 37b and 37d of raised regions 34a, 34b and
34d are at an angle with respect to the vertical, typically
45.degree., which ensures that they smoothly give way under the
user's weight and thereby not provide their own rigid structural
support.
A third preferred embodiment, of the present invention is shown in
FIG. 6, the insole being disposed within shoe structure 40. In this
embodiment, as in the second embodiment, the present invention
insole structure is an integral part of the shoe 40 and is
incorporated therein during the process of manufacturing the shoe
40.
An inner sole 42 of the shoe 40 is utilized to provide the lower
surface of the insole structure. Compartments 44a - 44d are
configured in the upper region of the inner sole 42 to a depth of
about 1/8 of an inch. The area, shape and location of the
compartments 44a - 44d are selected to provide cushioning and
support to particular portions of its foot. In this preferred
embodiment of the present invention 40, four compartments are
depicted so that cushioned support is provided to the toes, ball,
instep and heel respectively. An upper surface 46 is disposed over
the inner sole 42 and secured thereto, as well as to the structure
of shoe 40, by methods known in the art. Surface 46 is made of a
flexible plastic material, preferably of one of the kinds described
above. The joining of surface 48 to inner sole 42 seals the
compartments 44a - 44d which become the internal fluid 44' filled
cavities characteristic of the invented insole structure. The
manner in which the above described structure provides cushioned
support to the user's feet is the same as has been described with
respect to the first embodiment.
A moisture-absorbing covering 48 is preferably disposed upon the
top of surface 46 and secured thereto, as well as to the structure
of the shoe 40.
An additional feature which is preferable in the embodiments of the
present invention is the presence of air holes or channels 90 in
the insole structure at locations which do not effect the
structure's capability to contain the fluid in the cavities
therein. The purpose of such air holes or channels is to enable the
circulation of air within the item of footwear; i.e., to enhance
the ventilation of its inner regions.
The present invention also contemplates embodiments, structurally
independent of the footwear, which can be characterized as partial
insoles; i.e., insoles configured to cushion and support only one
portion of the user's foot. These partial insoles are inserted into
the item of footwear at the locations at which they are adapted for
use. With reference to FIGS. 7-9 those preferred forms of the
partial insole embodiments of this invention are shown. In FIG. 7
insole 50, adapted to support and cushion the ball of the foot, is
shown. It has a single fluid-filled cavity formed, as in the other
embodiments, by upper and lower surfaces, the lower surface having
a single raised region 52 with sloping walls 54. In FIG. 8 an
insole 60, adapted to support and cushion the arch of the foot, is
shown. It too has a single fluid-filled cavity similar in
construction to that of insole 50. FIG. 9 depicts a similar single
cavity insole 70 adapted to support and cushion the heel. These
three embodiments also contemplate the addition of a
moisture-absorbing fabric, secured to the top of the upper surface,
to enhance the user's comfort by reducing the build-up of excess
moisture.
The plastic surfaces which comprise the invented insole structure
can be produced by conventional plastic forming techniques such as
injection molding, vacuum molding or blow molding. When either
injection molding or vacuum molding processes are utilized, the
upper and lower surfaces are typically separate elements and must
be joined together with leakproof bond. This can be accomplished by
methods and materials known in the art. The fluid which is
encapsulated in the cavities formed within the body of the insole
structure can be encapsulated during the process of joining the
upper and lower section of the structure, or afterwards, by known
fluid injection and sealing techniques.
With reference to FIGS. 1-3, a fabric covering 16 was described,
secured to the top of upper surface 10 along its edges by a lip 18
of upper surface 10. This configuration can be produced during the
injection molding of the upper surface 10 in a similar manner to
that described in applicants U.S. Patent identified hereabove.
Prior to injecting the plastic material into the mold, the covering
16 is inserted into the mold, the outer edge of which extends
approximately 1/32 of an inch into the area that will be permeated
with the injected plastic. Thus, when the plastic material is
injected, the lip 18 will form around the outer edge of the
covering 16, thereby securing it to the top of the upper surface
10.
The insole structure which is structurally independent of the item
of footwear, i.e., the first preferred embodiment disclosed above,
lends itself to production by the techniques of blow molding. By
this method, an integral structure is formed. This has the
advantage of eliminating the steps of bonding separate upper and
lower surfaces; and further, it eliminates the risk of fluid
leakage due to defective bonding. Blow molding an insole adapted
for insertion into footwear, of course, is done while the plastic
material is in a semi-molten state. After the structure is molded,
and while the plastic is still semi-molten, the upper and lower
surfaces are joined in the areas between the raised regions by the
application of heat and pressure. In this manner separate sealed
internal cavities are formed. The fluid is injected into the
cavities by means of an appropriate injection apparatus, after
which the hole caused during injection is heat sealed.
Other embodiments, modifications and extensions of this invention
will become apparent to those skilled in the art. All such
variations which basically rely on the teachings which this
invention has advanced are considered within the spirit and scope
of this invention.
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