U.S. patent application number 10/628859 was filed with the patent office on 2005-02-03 for modular seat cushion with interlocking human support and base portions and method of creating and using a seat cushion.
Invention is credited to Bieganek, Joseph S., Hetzel, Thomas R..
Application Number | 20050023872 10/628859 |
Document ID | / |
Family ID | 34103468 |
Filed Date | 2005-02-03 |
United States Patent
Application |
20050023872 |
Kind Code |
A1 |
Hetzel, Thomas R. ; et
al. |
February 3, 2005 |
Modular seat cushion with interlocking human support and base
portions and method of creating and using a seat cushion
Abstract
A modular seat cushion includes a human interface portion and a
base portion which are combined and interlocked or interconnected
together. The human interface portion has an upper support contour
for supporting the user, and the base portion has a contact
configuration for contacting a variety of different types of seat
support structures. By selecting among human interface portions
that have different sizes and shapes of support contours and by
selecting among base portions that have a contact configuration
appropriate for the seat support structure, a seat cushion is
obtained which accommodates both the user and the type of seat
support structure with which it is used. The ability to combine the
human interface and base portions is particularly useful for
wheelchairs.
Inventors: |
Hetzel, Thomas R.;
(Littleton, CO) ; Bieganek, Joseph S.; (Littleton,
CO) |
Correspondence
Address: |
JOHN R LEY, LCC
5299 DTC BLVD, SUITE 610
GREENWOOD VILLAGE
CO
80111
US
|
Family ID: |
34103468 |
Appl. No.: |
10/628859 |
Filed: |
July 28, 2003 |
Current U.S.
Class: |
297/256.16 |
Current CPC
Class: |
A61G 5/1043 20130101;
A61G 7/05715 20130101; A61G 5/1045 20161101; A61G 5/1054 20161101;
A61G 7/05723 20130101 |
Class at
Publication: |
297/256.16 |
International
Class: |
A47C 001/08 |
Claims
What is claimed:
1. A modular seat cushion for supporting a person against a seat
support structure of a predetermined configuration, comprising: a
human interface portion having an upper surface defining a support
contour for supporting an anatomical portion of the person while
seated on the cushion and also having a lower surface defining a
first one of two complementary portions of an interlocking
structure; and a base portion having an upper surface defining a
second one of the two complementary portions of the interlocking
structure and also having a lower surface defining a contact
configuration for contacting the seat support structure, the second
complementary portion interconnecting with the first complementary
portion upon contacting the lower surface of the human interface
portion with the upper surface of the base portion, the contact
configuration having a predetermined shape which complements at
least a portion of the predetermined configuration of the seat
support structure which the contact configuration contacts.
2. A modular seat cushion as defined in claim 1, wherein: the human
interface portion and the base portion are both formed of resilient
synthetic plastic support material.
3. A modular seat cushion as defined in claim 2, wherein: the
resilient synthetic plastic support material is breathable.
4. A modular seat cushion as defined in claim 1, wherein: the human
interface and base portions each comprise resilient plastic beads
which have been fused together.
5. A modular seat cushion as defined in claim 4, wherein: the first
and second complementary portions of the interlocking structure are
formed of flexible plastic beads which have been fused
together.
6. A modular seat cushion as defined in claim 4, wherein: the human
interface and base portions are formed substantially entirely of
the fused together resilient plastic beads.
7. A modular seat cushion as defined in claim 2, wherein: the first
and second complementary portions of the interlocking structure are
formed integrally with the human interface and base portions,
respectively; and the first and second complementary portions of
the interlocking structure are formed of the resilient synthetic
plastic support material from which the human interface and base
portions are formed.
8. A modular seat cushion as defined in claim 1, wherein: the first
and second complementary portions of the interlocking structure
extend substantially over the entire area of the lower surface and
the upper surface of the human interface portion and the base
portion, respectively.
9. A modular seat cushion as defined in claim 1, wherein: the
contact configuration extends substantially over the entire area of
the lower surface of the base portion.
10. A modular seat cushion as defined in claim 1, wherein: the seat
support structure substantially complements the entire contact
configuration.
11. A modular seat cushion as defined in claim 1, wherein: the seat
support structure is part of a wheelchair; and the seat support
structure is one selected from a group consisting of a platform
seat, sling seat, dropped platform seat, pan seat and seat
shell.
12. A modular seat cushion as defined in claim 1, wherein: the
lower and upper surfaces of the human interface and base portions,
respectively, are of a substantially complementary shape with one
another; the interlocking structure comprises the complementary
lower and upper surfaces of the human interface and base portions,
respectively.
13. A modular seat cushion as defined in claim 1, wherein: one of
the first or second complementary portions of the interlocking
structure comprises a protrusion extending from the lower or upper
surface of the human interface or base portions, respectively; the
other one of the first or second complementary portions of the
interlocking structure comprises a recess formed into the lower or
upper surface of the human interface or base portions,
respectively; and the recess has a complementary configuration and
size to the configuration and size of the protrusion.
14. A modular seat cushion as defined in claim 13, wherein: the
protrusion extends outward from the lower surface of the human
interface portion; and the recess extends inward from the upper
surface of the base portion.
15. A modular seat cushion as defined in claim 14, wherein: the
interlocking structure comprises the lower surface of the human
interface portion from which the protrusion extends and the upper
surface of the base portion into which the recess extends.
16. A modular seat cushion as defined in claim 14, wherein: a
portion of the lower surface of the human interface portion
adjacent to the protrusion has a complementary shape to a portion
of the upper surface of the base portion adjacent to the recess;
and the interlocking structure comprises the portion of the lower
surface of the human interface portion adjacent to the protrusion
and the portion of the upper surface of the base portion adjacent
to the recess.
17. A modular seat cushion as defined in claim 14, wherein: the
recess extends completely through the base portion to define a hole
in the base portion.
18. A modular seat cushion as defined in claim 17, wherein: the
protrusion extends through the hole in the base portion and
contacts the seat support structure when the human interface and
base portions are interconnected together and the cushion is
supported by the seat support structure.
19. A modular seat cushion as defined in claim 1, further
comprising: a covering that encases the interconnected human
interface and base portion portions.
20. A modular seat cushion as defined in claim 1, wherein: the
human interface portion is one of a plurality of different human
interface portions; each different human interface portion has a
different support contour; the base portion is one of a plurality
of different base portions; each different base portion has a
different contact configuration; and the first complementary
portion of the interlocking structures of all of the plurality of
different human interface portions are consistent in configuration
with one another; and the second complementary portion of the
interlocking structures of all of the plurality of different base
portions are consistent in configuration with one another.
21. A modular seat cushion as defined in claim 20, wherein: the
support contour of one of the plurality of different human
interface portions accommodates the specific anatomy of the
person.
22. A modular seat cushion as defined in claim 21, wherein: at
least two human interface portions of the plurality of different
human interface portions each have a different support contour; and
each of the different support contours accommodates respectively
different generalized anatomical proportions of a person within one
of at least two different generalized classes of persons.
23. A modular seat cushion as defined in claim 20, wherein: each of
the different support contours accommodates respectively different
generalized anatomical proportions of a person within one of at
least two different generalized classes of persons.
24. A modular seat cushion as defined in claim 1, wherein: the
predetermined configuration of the seat support structure includes
a portion which has essentially the same shape characteristics as
the second complementary portion of the interlocking structure of
the base portion; and the first complementary portion of the
interlocking structure of the human interface portion interconnects
with the portion of the seat support structure which has
essentially the same shape characteristics as the second
complementary portion of the interlocking structure.
25. A modular seat cushion as defined in claim 1, wherein: the
predetermined configuration of the seat support structure includes
a portion which has a shape that is complementary to the first
complementary portion of the interlocking structure of the human
interface portion; and the first complementary portion of the
interlocking structure of the human interface portion interconnects
with the portion of the seat support structure which has a shape
that is complementary to the first complementary portion of the
interlocking structure.
26. A modular seat cushion as defined in claim 1, wherein: the seat
support structure includes the base portion; and the second
complementary portion of the interlocking structure and the contact
configuration of the base portion are formed in the seat support
structure as a unitary structure having the shape of the second
complementary portion of the interlocking structure.
27. A modular seat cushion as defined in claim 26, further
comprising: a covering that encases the human interface.
28. A base structure for attaching a human interface portion of a
seat cushion to a seat support structure of a wheelchair, the human
interface portion including a support contour for supporting an
anatomical portion of a person on the cushion, the seat support
structure having a predetermined configuration for supporting the
seat cushion and the person seated on the cushion, the base
structure comprising: an upper surface having a configuration which
complements and interconnects with a portion of the human interface
portion other than the support contour; and a lower surface having
a configuration which complements and contacts a portion of the
predetermined configuration of the seat support structure.
29. A base structure as defined in claim 28, wherein: the base
structure and the human interface portion are formed of resilient
synthetic plastic support material.
30. A base structure as defined in claim 28, wherein: the seat
support structure is one selected from a group consisting of a
platform seat, sling seat, dropped platform seat, pan seat and seat
shell.
31. A base structure as defined in claim 30, wherein: the support
contour of the human interface portion is one of the plurality of
different support contours each of which accommodates a person of
different anatomical characteristics.
32. A method of creating a modular seat cushion to support a person
from a seat support structure of a predetermined configuration,
comprising: selecting a human interface portion for the cushion
from among a plurality of different human interface portions, each
different human interface portion having a different support
contour for supporting a person having different anatomical
characteristics while seated on the cushion; selecting a base
portion for the cushion from among a plurality of different base
portions, each different base portion having a different contact
configuration which complements at least a portion of the
predetermined configuration of a different seat support structure;
combining the selected human interface portion with the selected
base portion to accommodate the anatomical characteristics of the
person seated on the cushion and the predetermined configuration of
the seat support structure.
33. A method as defined in claim 32, further comprising: combining
the selected human interface portion with the selected base portion
by interlocking the selected human interface and base portions.
34. A method as defined in claim 33, further comprising:
interlocking the selected human interface portion with the selected
base portion by interconnecting complementary portions of the
selected human interface and base portions.
35. A method as defined in claim 32, further comprising:
interconnecting the complementary portions of any of the plurality
of different human interface portions with any of the different
base portions.
36. A method as defined in claim 32, wherein the seat support
structure includes a portion having a predetermined configuration
which duplicates the complementary portion of the base portion, and
the method further comprises: using the duplicative complementary
portion of the seat support structure as the base portion; and
interconnecting the complementary portions of the selected human
interface portion and the seat support structure.
37. A method as defined in claim 32, wherein the complementary
portions of the human interface portion and the base portion
comprise a protrusion extending from one of the human interface or
the base portions and a receptacle extending into the other one of
the human interface or base portions, and the method further
comprises: interconnecting the protrusion within the
receptacle.
38. A method as defined in claim 32, further comprising: preventing
the complementary portions from deforming out of the interconnected
relationship when the person is seated on the support contour by
contacting the contact configuration with the seat support
structure.
39. A method as defined in claim 32, further comprising: selecting
the human interface portion as one having a support contour which
specifically accommodates specific anatomical characteristics of a
singular person.
40. A method as defined in claim 39, further comprising: selecting
the human interface portion as one having a support contour which
generally accommodates the anatomical characteristics of a general
class of persons.
41. A method as defined in claim 32, further comprising: selecting
the human interface portion as one having a support contour among a
plurality of support contours each of which generally accommodates
the anatomical characteristics of a general class of persons.
42. A method as defined in claim 32, wherein the seat support
structure is part of a wheelchair.
43. A method as defined in claim 42, wherein the seat support
structure is one of a group consisting of a platform seat, sling
seat, dropped platform seat, and seat shell.
44. A method as defined in claim 32, further comprising: selecting
the human interface and base portions as ones formed of resilient
and breathable synthetic plastic support material.
45. A method as defined in claim 32, further comprising: selecting
the human interface and base portions as ones formed of resilient
synthetic plastic beads which have been fused together.
46. A method of supporting a person on a cushion in a wheelchair
from a seat support structure of a predetermined configuration,
comprising: selecting a human interface portion for the cushion
from among a plurality of different human interface portions, each
different human interface portion having a different support
contour for supporting a person having different anatomical
characteristics while seated on the cushion; selecting a base
portion for the cushion from among a plurality of different base
portions, each different base portion having a different contact
configuration which complements at least a portion of the
predetermined configuration of a different seat support structure;
combining the selected human interface portion with the selected
base portion; positioning the contact configuration of the base
portion into complementary contact with the predetermined
configuration of the seat support structure; and seating the person
on the support contour with the anatomical portion of the person in
contact with the support contour of the human interface portion
while the base portion is in complementary contact with the
predetermined configuration of the seat support structure.
47. A method as defined in claim 46, further comprising:
maneuvering the wheelchair by action of the user while seated on
the cushion.
48. A method as defined in claim 47, further comprising: removing
the person from sitting on the support contour of the selected
human interface portion; substituting a different selected human
interface portion with a different support contour for the
previously selected human interface portion; combining the selected
substituted human interface portion with the selected base portion;
and thereafter reseating the person on the support contour of the
selected substituted human interface portion with the support
contour of the substituted human interface portion in contact with
the anatomical portion of the person while the base portion is in
complementary contact with the predetermined configuration of the
seat support structure.
49. A method as defined in claim 48, further comprising:
maneuvering the wheelchair by action of the user while reseated on
the support contour of the selected substituted human interface
portion.
50. A method as defined in claim 46, further comprising: removing
the person from sitting on the support contour of the selected
human interface portion; substituting a different selected human
interface portion with a different support contour for the
previously selected human interface portion; combining the selected
substituted human interface portion with the selected base portion;
and thereafter reseating the person on the support contour of the
selected substituted human interface portion with the support
contour of the substituted 10 human interface portion in contact
with the anatomical portion of the person while the base portion is
in complementary contact with the predetermined configuration of
the seat support structure.
51. A method of attaching a human interface portion of a seat
cushion to a seat support structure of a wheelchair, the human
interface portion including a support contour for supporting an
anatomical portion of a person on the seat cushion, the seat
support structure having a predetermined configuration for
supporting the seat cushion and the person seated on the cushion,
the method comprising: interposing a base portion between the human
interface portion and the seat support structure of the wheelchair;
interconnecting the base portion and the human interface portion;
and contacting the base portion in a complementary manner with the
predetermined configuration of the seat support structure.
52. A method as defined in claim 51, wherein the base structure and
the seat cushion are formed of resilient synthetic plastic support
material.
53. A method as defined in claim 51, further comprising: selecting
the seat support structure from a group consisting of a platform
seat, sling seat, dropped platform seat, pan seat and seat
shell.
54. A method as defined in claim 53, further comprising: selecting
the support contour of the human interface portion from a group of
human interface portions each of which has a different support
contours to accommodate different anatomical characteristics.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This invention is related to other inventions made by at
least one of the inventors herein for Individually-Contoured Seat
Cushion and Shape Capturing and Fabricating Method for Seat Cushion
described in U.S. patent application Ser. No. [249.301], and for
Contoured Seat Cushion and Method for Offloading Pressure from
Skeletal Bone Prominences and Encouraging Proper Postural Alignment
described in U.S. patent application Ser. No. [249.303], and for
Apparatus and Method for Evaluating Clearance from a Contoured Seat
Cushion described in U.S. patent application Ser. No. [249.304],
all of which are filed concurrently herewith and all of which are
assigned to the assignee of the present invention. The subject
matter of these concurrently-filed applications is incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to seat cushions, and more
particularly, to a new and improved modular seat cushion formed by
a human support portion and an interlocking base portion. The human
support portion provides individualized support for the user, and
the base portion fits with, is accepted by, or becomes part of a
seat support structure. By forming the seat cushion in this modular
form, improved support, utility and comfort is available to the
user for a relatively modest cost. The present invention is
particularly useful to create seat cushions for wheelchairs,
although the broader aspects of the invention are not limited
specifically to such use.
BACKGROUND OF THE INVENTION
[0003] A wheelchair seat cushion must perform a number of important
functions. The seat cushion should be comfortable and capable of
providing proper support for optimal posture and posture control
for a considerable length of time. The seat cushion should also
assist, or at least not materially hinder, the user in maneuvering
the wheelchair, permit a useful range of motion from the pelvis and
upper torso of the person, and create stability and security for
the person within the wheelchair. Perhaps most importantly, the
seat cushion should help prevent and reduce the incidence of
pressure ulcers created by prolonged sitting on the cushion without
adequate pressure relief. Pressure ulcers can become a very serious
health problem for individuals who must remain constantly in
contact with the support cushion, and it is important to avoid such
pressure ulcers.
[0004] Wheelchair users like everyone are of substantially
different sizes, weights and shapes. Many wheelchair users have
physical disabilities and associated posture and postural control
impairments such as those typically caused by congenital disorders.
Other wheelchair users, such as those who have been disabled by
acquired or traumatic injuries, may have a more typical size and
shape. In all of these cases, the support contour of the wheelchair
seat cushion must safely support the anatomy of the user, whether
the anatomy is abnormal or more typical. Wheelchair seat cushions
must fit and perform properly to prevent further physical
impairment and pressure ulcers. The cushion must also enhance the
functional capabilities of the user by supporting independence in
activities of daily living. There are a number of different
theories or approaches for configuring the support contour of a
wheelchair seat cushion to avoid pressure ulcers and to provide
adequate postural alignment.
[0005] A variety of different wheelchairs are also available. Many
of these different wheelchairs have physically different
constructions and shapes. The seat support structures of these
wheelchairs may vary substantially. One type of wheelchair seat
support structure is a sling seat. A sling seat is made of fabric
material that is suspended between two frame rails of the
wheelchair. The wheelchair cushion is placed on top of the sling
seat. A sling seat will bend or sag downward due to the weight of
the user and its flexible nature. A platform seat is another type
of wheelchair seat structure. A platform seat is generally a flat
and rigid structure which is connected on top of the wheelchair
frame rails. The cushion is placed on top of the platform seat. A
drop seat is similar to a platform seat, except that the platform
is located and suspended below the frame rails. A drop seat
positions the person closer to the ground and creates a slightly
lower center of gravity for the wheelchair and user. Shell seats
and pan seats may also be used as wheelchair seat support
structures. A shell seat is a single chair-like shape having a seat
bottom and a seat back. In general, a shell seat is used when the
wheelchair user is incapable of supporting himself or herself. A
pan seat is similar to the seat bottom of a shell seat or to a
curved platform seat. A pan seat may be used under special
circumstances where other types and forms of wheelchair seat
supports are not appropriate or preferred.
[0006] To provide the best wheelchair cushion for a user, the
cushion must be designed to accommodate and support the anatomy and
functional preferences of the user, as well as the type of seat
support structure preferred by the user. In general, the
predominant previous approach to accommodating these requirements
has involved using generic wheelchair cushions which have some
capability of adapting to the anatomical shape of the user and then
rigging an attachment of the cushion to the wheelchair. The ability
of the cushion to adapt to different users is often accomplished by
soft, flowable or adaptable cushion material which redistributes
under the weight of the user to accommodate the different
anatomical shapes of different users. The attachment of the cushion
to the wheelchair usually requires additional use of auxiliary
attachment devices and hardware which must oftentimes be
specifically fabricated for that purpose.
[0007] Generic seat cushions may not be comfortable or offer the
best fit for a particular user. The size, posture and anatomical
characteristics of an individual may influence the comfort and fit
of the seat cushion. Certain of these anatomical areas have a
prominent skeletal bone structure. Excessive pressure in the areas
of prominent bone structure increases the risk of pressure ulcers
which can have very serious medical consequences. The problems of
existing seat cushions are discussed more completely in the
concurrently filed U.S. patent application Ser. No. [249.303]
referenced above.
[0008] Having a custom wheelchair cushion built to accommodate the
anatomy and preferences of a specific individual is an option which
overcomes the disadvantages associated with generic wheelchair
cushions. There are a number of very sophisticated methods and
devices available to create custom wheelchair cushions, but the
ability to capture and use the anatomical shape of the user when
creating the cushion is very important, as discussed in U.S. patent
application Ser. No. [249.301] referenced above. Furthermore, even
if the support contour of the custom cushion is initially
satisfactory, that support contour may ultimately prove to be
inappropriate or uncomfortable after the cushion has been used for
some period of time. Tissue changes influenced by continually
sitting on the cushion over some period of time may change the
optimal support and comfort characteristics. It is also typical
that tissue may atrophy over time, particularly for first-time
wheelchair users, further compromising cushion fit.
[0009] Another problem with custom wheelchair cushions is that the
user is not able to test or try the cushion before it is
fabricated. The user cannot evaluate the support from the cushion
and cannot evaluate the seating position in the wheelchair. If the
cushion positions the user too far forward or rearward, or too low
or high, the ability of the user to turn the drive wheels and
maneuver the wheelchair is adversely affected. Turning the drive
wheels also causes the pelvis and torso of the user to rock forward
and backward. This movement is normal and desirable, but may
increase the shear forces experienced at the seat interface thereby
further elevating risk for skin breakdown and pressure ulcers.
[0010] The cost of a custom wheelchair or cushion can also be a
substantial detriment. Creating a custom wheelchair cushion may
cost in the neighborhood of approximately $3000 or more. Custom
cushions are expensive because of the time consumed to make them
and the cost of the relatively sophisticated equipment necessary to
simulate individual anatomical contours of the user into a support
contour of the custom cushion.
[0011] Connecting and adapting any of these seat cushions to a
wheelchair seat support structure is not an insignificant matter.
Each different type of wheelchair seat support structures usually
requires a different type of attachment arrangement. Standard
attachment hardware for each different type of wheelchair seat
support structure is not readily available. Consequently, auxiliary
attachment hardware and devices must be individually ordered or
fabricated. Varying degrees of functionality and success in
attaching the seat cushion are common results in such
circumstances. In general, the auxiliary attachment hardware adds
weight to the wheelchair, making maneuverability of the wheelchair
more difficult or strenuous.
[0012] Many of the same considerations also apply with varying
levels of criticality to other uses of seat cushions. For example,
seat cushions used in office environments are required to support
the user in a comfortable manner which encourages proper posture
and without creating risks of medical problems, for example
inducing blood circulatory problems.
SUMMARY OF THE INVENTION
[0013] The present invention obtains the benefits of a custom seat
cushion at a modest fraction of the typical cost for a custom seat
cushion, while simultaneously facilitating attachment and support
of the cushion to a seat support structure. To do so, the seat
cushion is formed in two portions. An upper human interface portion
defines a support contour for the user's anatomy while seated. A
lower base portion defines a contact configuration which
complements and is supported against a seat support structure. The
human interface portion and the base support portion are
interconnected to complete the cushion.
[0014] The human interface portion is preferably formed with
different support contours, thereby allowing human interface
portion to be selected for use which best accommodates the anatomy
of the user. A relatively small number of human interface portions,
for example three, with different sized and shaped support contours
will accommodate a significant population of users having normal
anatomies. For those wheelchair users who have an abnormal anatomy,
the human interface portion is formed with a specific custom
support contour to accommodate the peculiarities of the abnormal
anatomy. The lower base portion accommodates the user's preference
for a type of seat support structure. Examples of wheelchair seat
support structures include a platform seat, a sling seat, a dropped
platform seat, a pan seat and a shell seat. A number of different
base portions, each with a different contact configuration, allows
the cushion to be used with any of the typical seat support
structures without the need for cost of additional parts and
accessories. Interconnecting the upper human interface portion with
the lower base portion allows the seat cushion to complement the
anatomy of the user and the seat support structure without the need
for and cost of additional parts and accessories.
[0015] The user can test or demonstrate the modular cushion to
confirm that it provides the desired comfort and maneuverability
prior to accepting the completed cushion. To the extent that
testing demonstrates that changes are required, those changes may
be achieved by interchanging one or both of the upper human
interface and lower base portions. Future adjustments in the seat
cushion can be accomplished by changing one or both of the upper
human interface portion or the lower base portion to accommodate
changes in the user's needs or preference for seat support
structures, respectively. Because most of the human interface
portions and the base portions are standard configurations, they
can be mass produced for much less cost than if the entire cushion
was custom made. In most cases, there is no need for a custom
cushion, because a cushion can be assembled from standard
variations of human interface portions. Furthermore, assembling the
cushion from the standard human interface and base portions will
make the completed cushion available for use on a more rapid
basis.
[0016] One aspect of the invention involves a modular seat cushion
which includes the human interface portion and the base portion.
The human interface portion has an upper surface area defining a
support contour for supporting an anatomical portion of the person
while seated on the cushion. The human interface portion also has a
lower surface area defining a first one of two complementary
portions of an interlocking structure. The base portion has an
upper surface area defining a second complementary portion of the
interlocking structure and also has a lower surface area defining a
contact configuration. The first and second complementary portions
of the interlocking structure interconnect with one another when
the lower surface area of the human interface portion contacts the
upper surface area of the base portion. The contact configuration
has a predetermined shape which complements at least a portion of
the seat support structure.
[0017] Another aspect of the invention involves a method of
creating a modular seat cushion. The method comprises selecting a
human interface portion from among a plurality of different human
interface portions which each have a different support contour,
selecting a base portion from among a plurality of different base
portions which each have a different contact configuration for a
seat support structure, and combining the selected human interface
portion with the selected base portion to position the support
contour in complementary contact with the anatomical portion of the
person and to position the contact configuration in complementary
contact with the seat support structure.
[0018] Another aspect of the invention involves supporting a person
on a seat support structure. This method comprises selecting the
human interface portion with the desired support contour, selecting
the base portion with the desired contact configuration, combining
the selected human interface portion with the selected base
portion, positioning the contact configuration into complementary
contact with the seat support structure, and seating the person on
the cushion with the anatomical portion of the person in contact
with the support contour of the human interface portion.
[0019] Another aspect of the invention involves including in the
seat support structure a portion which has essentially the same
shape characteristics as the second complementary portion of the
interlocking structure of the base portion, and then interfitting
the selected human interface portion with the seat support
structure.
[0020] Another aspect of the invention involves attaching a human
interface portion of a seat cushion to a seat support structure of
a wheelchair. The human interface portion includes a support
contour for supporting an anatomical portion of a person on the
seat cushion, and the seat support structure has a predetermined
configuration for supporting the seat cushion and the person seated
on the cushion. The method involves interposing a base portion
between the human interface portion and the seat support structure
of the wheelchair, interconnecting the base portion and the human
interface portion, and contacting the base portion in a
complementary manner with the predetermined configuration of the
seat support structure.
[0021] The present invention is particularly applicable to seat
cushions for wheelchairs. Other preferable features of the
invention involve forming the human interface and base portions
from flexible support materials such as a resilient breathable
plastic foam material, forming the complementary interlocking
portions of the interlocking structure from the flexible support
material, and employing consistent complementary portions of the
interlocking structure so that the different human interface
portions and base portions will interfit and connect together.
[0022] A more complete appreciation of the scope of the present
invention and the manner in which it achieves the above-noted and
other improvements can be obtained by reference to the following
detailed description of presently preferred embodiments taken in
connection with the accompanying drawings, which are briefly
summarized below, and by reference to the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is an exploded and perspective view of a wheelchair
and a modular seat cushion which incorporates the present
invention, with a portion of the seat cushion shown broken away to
show the internal structure of the seat cushion.
[0024] FIG. 2 is an enlarged and exploded downward-looking
perspective view of the top of a top human interface portion and
the top of a bottom base portion of the seat cushion shown in FIG.
1.
[0025] FIG. 3 is a upward-looking perspective view of the bottom of
the top human interface portion and the bottom of the base portion
shown in FIG. 2.
[0026] FIG. 4 is a longitudinal and vertical cross-sectional view
of the seat cushion shown in FIG. 1 taken substantially in the
plane of line 4-4, with the human interface and bottom support
portions shown in an interconnected relationship.
[0027] FIG. 5 is an exploded front elevational view of a wheelchair
having a platform seat support structure, and a wheelchair seat
support cushion formed by a combined human interface portion and a
base portion, as shown in FIG. 1, in which the base portion has a
contact configuration which complements the platform seat support
structure.
[0028] FIG. 6 is an exploded front elevational view of a wheelchair
having a sling seat support structure, and a wheelchair seat
cushion formed by a combined human interface portion and a base
portion, similar to that shown in FIG. 1, in which the base portion
has a contact configuration which complements the sling seat
support structure.
[0029] FIG. 7 is an exploded front elevational view of a wheelchair
having a dropped platform seat support structure, and a wheelchair
seat cushion formed by a combined human interface portion and a
base portion, similar to that shown in FIG. 1, in which the base
portion has a contact configuration which complements the dropped
platform seat support structure.
[0030] FIG. 8 is an exploded front elevational view of a wheelchair
having a pan seat support structure, and a wheelchair seat cushion
formed by a combined human interface portion and a base portion,
similar to that shown in FIG. 1, in which the base portion has a
contact configuration which complements the pan seat support
structure.
[0031] FIG. 9 is an exploded front elevational view of a wheelchair
having another pan seat support structure, different from that
shown in FIG. 8, and a wheelchair seat cushion formed by a combined
human interface portion and a base portion, similar to that shown
in FIG. 1, in which the base portion is a part of the pan seat
support structure.
[0032] FIG. 10 is an exploded front elevational view of a
wheelchair having a shell seat support structure, and a wheelchair
seat cushion formed by a combined human interface portion and a
base portion, similar to that shown in FIG. 1, in which the base
portion is a part of the shell seat support structure.
[0033] FIG. 11 is chart illustrating the combination of different
human interface portions and base portions of the seat cushion
shown in FIGS. 1-10 to accommodate the different types of the
wheelchair seat support structures shown in FIGS. 5-10.
DETAILED DESCRIPTION
[0034] A modular wheelchair seat cushion 20 is used with a seat
support structure 22 of a conventional wheelchair 24 as shown in
FIG. 1. One embodiment of the seat cushion 20 comprises a human
interface portion 26 and a base portion 28 which fit together in an
interlocking manner, as shown in FIGS. 1-4. Another embodiment of
the seat cushion 20 interlocks the human interface portion 26 with
a complementary portion of a seat support structure, as shown in
FIGS. 9 and 10. The human interface portion 26, and the base
portion 28 (when used), are covered by a conventional covering 30
to complete the seat cushion 20.
[0035] An upward-facing support contour 32 is formed in the human
interface portion 26 to support the user when the user sits on the
cushion 20, as shown in FIGS. 1, 2 and 4. Different human interface
portions 26 will each have differently-shaped support contours 32
to accommodate the different anatomies of different users, when the
user sits on the support contour 32 of the cushion 20.
[0036] The base portion 28 includes a downward-facing contact
configuration 34 which interacts with a particular type of seat
support structure 22. Examples of different types of wheelchair
seat support structures 22 are a platform seat 36, shown in FIGS.
1, 4 and 5; a sling seat 38, shown in FIG. 6; a dropped platform
seat 40, shown in FIG. 7; a pan seat 42, shown in FIG. 8; another
type of pan seat 44, shown in FIG. 9; and a shell seat 46, shown in
FIG. 10. All of these wheelchair seat support structures 36-46 are
typically connected to longitudinally extending rails 48 of a frame
50 of the wheelchair 24.
[0037] The interaction of the contact configuration 34 of the base
portion 28 with the seat support structure 22 maintains the cushion
20 in place on the wheelchair 24, in one embodiment of the
invention. In the other embodiment of the invention, the human
interface portion 26 directly interacts and complements a
particular type of seat support structure 22 without the use of a
separate base portion 28 of the cushion 20. In this second
embodiment, the portion of the human interface portion 26 which
normally interacts directly with the base portion 28 instead
directly interacts with the seat support structure 22 to hold the
human interface portion 26 in the seat support structure 22 without
the need of a separate base portion 28. The covering 30 typically
extends only over the human interface portion 26, in this second
embodiment.
[0038] By employing a particular support contour 32 of the human
interface portion 26 which comfortably fits and supports the
anatomy of a particular user, and by selecting a base portion 28 or
human interface portion 26 which has a contact configuration that
matches and conforms with the type of wheelchair seat support
structure 22, a wheelchair seat cushion 20 is obtained which offers
significant benefits for the user. The comfort and fit of the
support contour 32 offers the capability for significant freedom
from pressure ulcers. The cushion allows enhanced maneuverability,
stability and use of the wheelchair. These benefits are available
from any wheelchair having any of the common and conventional seat
support structures 22. By mass producing different human interface
portions 26 with different support contours 32 and by mass
producing different base portions 28 with different contact
configurations 34, and by then combining the human interface
portions 26 according to the anatomy of the user with the base
portions 28 according to the different types of wheelchair seat
support structures 22, the resulting cushion 20 can very closely
simulate the benefits of a custom wheelchair cushion, but without
the added cost of a custom wheelchair cushion. When a custom
cushion is required or desired by the user, only the support
contour 32 of the human interface portion 26 must be specially
fabricated, and not the entire cushion, since a standard base
portion 28 can be used with the specially fabricated human
interface portion 26. Standard contact configurations 34 make
retention on the wheelchair seat support structure relatively easy
to accomplish without incurring the cost and effort of modifying a
cushion to accommodate a particular wheelchair support structure
and without fabricating or using additional support and retention
hardware.
[0039] The human support contour 32 of the human interface portion
26 is illustrated in FIGS. 2 and 4. The support contour 32 may be
shaped to accommodate a normal human anatomy, with only the size
and proportion of the support contour 32 adjusted to accommodate
different sizes and shapes of users. The support contour 32 of the
human interface portion 26 may also be formed in a custom
configuration to accommodate the specific anatomical uniqueness of
a user who may not fit or prefer a standard variation support
control 32.
[0040] Preferably, the shape and proportion of the standard
variations in the support contour 32 will be as described in U.S.
patent application Ser. No. [249.303], referenced above. The
support contour described in this U.S. patent application has
considerable advantages and improvements in avoiding pressure
ulcers while providing improved postural alignment for the user.
Adjusting the size and proportion of this standard support contour
32 accommodates different sizes and shapes of the normal anatomy.
For example, one standard variation of the support contour 32 is
intended to primarily accommodate the wider spread and shallower
slope of the ischial tuberosities of the female skeletal bone
structure. Another standard variation of the support contour 32 is
intended to accommodate the narrower and steeper slope of the
ischial tuberosities of the male skeletal bone structure. Another
standard variation of the support contour 32 is not
gender-specific, but has a deeper and steeper profile. This deeper
and steeper support contour 32 may provide better protection for
individuals with soft tissue atrophy. However, regardless of sex or
degree of tissue atrophy, any user may prefer any one of these
different standard variations of support contours, depending on
personal comfort, support and preference.
[0041] In general, a variety of different support contours and
theories for supporting wheelchair users are known and available,
in addition to the subject matter described in U.S. application
Ser. No. [249.303]. Any type of support theory can be implemented
in the support contour 32 of the human interface portion 26, in
accordance with the present invention.
[0042] In those cases where an individualized or custom support
contour 32 is desired, that custom support contour 32 must be
derived and made from the particular anatomical characteristics of
the individual user. A number of known techniques are available to
create custom wheelchair cushions, and those known techniques may
be applied to create the support contour 32 and the human interface
portion 26 in accordance with the invention. One particularly
useful type of technique for creating a seat cushion is described
in U.S. patent application Ser. No. [249.301], referenced above.
That technique is applicable to fabricating both the human
interface portion 26 and the base portion 28.
[0043] The human interface portion 26 and the base portion 28 are
interconnected mated or interfitted together by an interlocking
structure 52. One example of an interlocking structure 52 is shown
in FIGS. 2-4. The interlocking structure 52 includes a protrusion
54 which extends downward (as shown) from a lower surface 56 of the
human interface portion 26. The protrusion 54 fits within a
complementary shaped recess 58 formed into the base portion 28 from
an upper surface 60 of the base portion. The lower surface 56 of
the human interface portion 26 and the upper surface 60 of the base
portion 28 are shaped in a mutually complementary manner, as shown
in FIG. 4. The surfaces 56 and 60 contact one another when the
protrusion 54 fits within the recess 58. The complementary
interfitting relationship of the protrusion 54 within the recess
58, and the complementary interfacing contact of the surfaces 56
and 60, interlock the human interface portion 26 with the base
portion 28, as shown in FIG. 4. When interlocked in this manner,
the portions 26 and 28 will not readily separate, particularly when
covered or encased with a relatively tight covering 30 (FIG. 1) or
when held together with adhesive. Although not shown, other
indexing configurations or shapes may be formed on the surfaces 56
and 60 to interfit with one another, to supplement and/or
substitute for the interfitting relationship of the protrusion 54
and the recess 58.
[0044] The interlocking structure 52 is of a consistent
configuration among all of the different types of human interface
portions 26 and base support portions 28. The protrusion 54 and the
lower surface 56 of the human interface portion 26 have consistent
shapes and dimensions on all of the different types of human
interface portions 26. Similarly, the recess 58 and the upper
surface 60 of the base portion 28 have consistent shapes and
dimensions on all of the base portions 28. Consequently, any of the
different types of human interface portions 26 will interconnect,
mate and interfit with any of the different types of the base
portions 26.
[0045] Depending upon the thickness of the base portion 28, the
recess 58 may extend completely through the base portion 28, in
which case the recess 58 constitutes a hole completely through the
base portion 28 as shown in FIGS. 2 and 4. In this embodiment when
the portions 26 and 28 are interlocked and placed on the seat
support structure 22 of the wheelchair, the protrusion 54 contacts
and rests against the seat support structure 22, separated only by
the thickness of the covering 30. Using a hole as the recess 58 in
the base portion 28 configuration allows the human interface
portion 26 to have a relatively deep support contour 32 while still
interfitting with the base support portion 28, and to maintain as
low of a center of gravity of the user as possible.
[0046] The contact configuration 34 of the base portion 28 includes
a lower surface 62 (FIGS. 3 and 4) which substantially fully
contacts and complements one type of wheelchair seat support
structure 22. The common and prevalently used types of wheelchair
seat support structures 22 are illustrated in FIGS. 5-10.
[0047] A typical platform wheelchair seat support structure 36 is
shown in FIGS. 1, 4 and 5. The platform seat support structure 36
is formed by a rigid, generally planar sheet member 64 which
extends between the rails 48 of the wheelchair frame 50. For
example, the sheet member 64 may be formed from plywood, metal, or
composite material. The sheet member 64 is attached to the rails 48
by conventional fasteners (not shown). The upper surface of the
sheet member 64 is planar. To fully contact and complement the
upper planar surface of the sheet member 64, the contact
configuration 34 of the base portion 28 is made as a planar surface
62a, shown in FIG. 5. When a base portion 28 with a lower planar
surface 62a rests on the upper planar surface of the sheet member
64, the shape of the recess 58 and upper surface 60 (FIGS. 2 and 4)
are not distorted from their intended shapes, thereby allowing the
protrusion 54 and the lower surface 56 to fit within and contact
the recess 58 and the upper surface 60, respectively, to interlock
the human interface portion 26 and the base portion 28.
[0048] A typical sling seat 38 is another type of wheelchair seat
support structure 22, shown in FIG. 6. The sling seat 38 is formed
by strong and flexible material 66, such as durable fabric, which
is connected or suspended in a sling-like manner between the rails
48. The material 66 is connected to each of the rails 48 by looping
each end of the material 66 around a longitudinally-extending
support bar (not shown) and then connecting each end of the
material 66 to the middle portion of the material 66 with a
conventional hook and loop fastener. The longitudinally extending
support bar (not shown) is then attached to the rails 48 with
conventional fasteners (not shown).
[0049] In general, the sling seat 38 will sag or curve downward
between the rails 28 as generally shown in FIG. 6. Consequently, in
order to fully contact and complement the curved shape of the
material 66 forming the sling seat 38, the contact configuration 34
of the base portion 28 is formed with a complementary
downwardly-curved convex lower surface 62b shown in FIG. 6. When a
base portion 28 with the downwardly-curved lower surface 62b rests
on the downwardly curved material 66 of the sling seat 38, the
shape of the recess 58 and upper surface 60 (FIGS. 2 and 4) are not
distorted from their intended shapes, thereby allowing the
protrusion 54 and the lower surface 56 to interfit with the recess
58 and the upper surface 60, respectively, and thereby interconnect
the human interface portion 26 and the base portion 28.
[0050] A typical dropped platform wheelchair seat support structure
40 is shown in FIG. 7. The dropped platform seat 40 is similar to
the platform seat 36 (FIG. 5), except that the dropped platform
seat 40 is suspended beneath and between the rails 48. The dropped
platform seat 40 is formed by a rigid, generally planar sheet
member 70 which is suspended from the rails 48 by suspension
brackets 72. For example, the sheet member 70 may be formed from
plywood, metal or composite material. Conventional fasteners (not
shown) connect the suspension brackets 72 to the sheet member 70
and connect suspension brackets 72 to the rails 48. The upper
surface of the sheet member 70 is planar, and the upper surface is
located at a position lower than the rails 48 of the wheelchair
frame 50 (FIG. 1).
[0051] To fully contact and complement the upper planar surface of
the sheet member 70, and to extend over the top of the rails 48,
the contact configuration 34 of the base portion 28 is formed as a
lower planar surface 62c with longitudinal edge recesses 74
extending along each transverse side of the base portion 28. The
recesses 74 fit around the suspension brackets 72 and the rails 48,
thereby allowing a portion of the base support 28 to extend over
and around the rails 48. When a base portion 28 with a planar lower
surface 62c and recesses 74 rests on the planar surface of the
sheet member 70 and fits around the suspension brackets 72 and the
rails 48, the shape of the recess 58 and upper surface 60 (FIGS. 2
and 4) are not distorted from their intended shapes, thereby
allowing the protrusion 54 and the lower surface 56 to interfit
with the recess 58 and the upper surface 60, respectively, and
thereby interconnect the human interface portion 26 and the base
portion 28.
[0052] A pan seat 42, shown in FIG. 8, is another type of
wheelchair seat support structure 22. The pan seat support
structure 42 may take a variety of different configurations. In
general, the pan seat 42 will always include a bottom wall 76 which
extends between the rails 48. The bottom wall 76 may be generally
planar, as shown in FIG. 8, or the bottom wall 76 may curve
slightly downward similar to the curve of the sling seat 38 (FIG.
6). The pan seat 42 may also include edges 78 which extend upward
from the periphery of the bottom wall 76. The edges 78 will not
extend along a front edge of the bottom wall 76 where the legs of
the user will bend when the user is seated in the pan seat 42. The
pan seat 42 is preferably formed of rigid material, for example
lightweight composite material. The pan seat 42 is attached to the
rails 48 by conventional fasteners (not shown) or rests on the
sling seat 38 (FIG. 6) with hook and loop attachment. In a sense,
the pan seat 42 is similar to the platform seat 36 (FIG. 5), except
that it may also include the edges 78 and may have a curved bottom
wall 76.
[0053] The contact configuration 34 of the base portion 28 is
formed as a surface 62d which has been curved and shaped in a
manner to fully contact and complement any curvature and shape of
the bottom wall 76. The base portion 28 should also be shaped to
fit within the edges 78. When a base portion 28 with an
appropriately-shaped contact surface 62d rests on the bottom wall
76 and within the edges 78, the recess 58 and upper surface 60
(FIGS. 2 and 4) are not distorted from their intended shapes,
thereby allowing the protrusion 54 and the lower surface 56 to
interfit with the recess 58 and the upper surface 60, respectively,
and interconnect the human interface portion 26 and the base
portion 28.
[0054] Another type of pan seat wheelchair support structure 44 is
shown in FIG. 9. The pan seat 44 is similar to the pan seat 42
(FIG. 8) but includes a receptacle 82 formed in a bottom wall 84 of
the pan seat 44. The receptacle 82 has the shape and configuration
of the recess 58 of the base portion 28 (FIGS. 2 and 4). In
addition, the upper surface of the bottom wall 84 which surrounds
the receptacle 82 has the shape and configuration of the upper
surface 60 of the base portion 28 (FIGS. 2 and 4). Shaped in this
manner, the receptacle 82 and the upper surface of the bottom wall
84 are capable of interconnecting in a complementary manner with
the protrusion 54 and the lower surface 56 of the human interface
portion 26 (FIGS. 3 and 4).
[0055] The human interface portion 26 is interconnected directly
with the pan seat 44 as a result of the protrusion 54 of the human
interface portion 26 extending into the receptacle 82 and the lower
surface 56 of the human interface portion 26 (FIGS. 2-4) resting on
the bottom wall 84 of the pan seat 44. Use of the base portion 28
(FIGS. 1-4) is unnecessary because a portion of the seat pan 44
becomes the base portion 26. Interconnecting the complementary
portions of the human interface portion 26 and the seat pan 44
interlocks the human interface portion 28 and the pan seat 44.
[0056] The pan seat 44 is attached to the rails 48 with fasteners
(not shown). The pan seat 44 may also include edges 78 which extend
upward from the periphery of the bottom wall 84, except that the
edges 78 will not extend along a front edge of the bottom wall 84
where the legs of the user will bend when the user is seated in the
pan seat 44. In the embodiment shown in FIG. 9, only the human
interface portion 26 is enclosed within a covering 30.
[0057] A complete shell seat 46 is another type of wheelchair seat
support structure 22, as shown in FIG. 10. The shell seat support
structure 46 includes a bottom wall 86 which may be similar in
shape and configuration to one of the bottom walls 76 and 84 of the
pan seats 42 and 44 (FIGS. 8 and 9), respectively. In addition, the
shell seat 46 includes a back wall 88 which extends vertically
upward from the bottom wall 86 at a location to contact the back of
the upper torso of the wheelchair user. The shell seat 46 may also
include edges 78 which extend longitudinally on opposite transverse
sides of the bottom wall 86, from the back wall 88 forward.
Preferably, the entire shell seat 46 is formed as a rigid integral
structure of lightweight composite material. The shell seat rests
on a sling seat 66 of a typical wheelchair and an anchoring strap
89 secures the seat to the wheelchair.
[0058] Depending upon the shape and configuration of the bottom
wall 86, the cushion 20 used with the shell seat 46 may or may not
include a base portion 28 (FIGS. 1-4). If the bottom wall 86 has a
configuration similar to the bottom wall 76 of the pan seat 42
shown in FIG. 8 but not shown in FIG. 10, the contact configuration
34 of the base portion 28 will be formed as a lower surface 62
which has a shape which complements the bottom wall 86. If the
bottom wall 86 has a configuration similar to the bottom wall 84 of
the pan seat 44 shown in FIG. 9 and also shown in FIG. 10, and
thereby includes the receptacle 82, the base portion 28 will not be
part of the cushion 20. Instead, the human interface portion 26
will interconnect directly with the bottom wall 86. Whether or not
a base portion 28 is used, the human interface portion 26 will be
retained within the shell seat 46. Although not shown in FIG. 10, a
cushion or other type of padding will typically be attached to the
back wall 88 to provide comfort, support and protection for the
upper torso of the user.
[0059] The human interface portion 26 and the base portion 28 may
be formed of flexible support material such as moldable plastic
foam. One particularly advantageous type of material from which to
make the human interface portion 26 and the base portion 28 is
plastic beads, as described more completely in U.S. patent
applications Ser. Nos. [249.301 and 249.303]. The plastic bead
material is fused together in such a way that spaces exist between
the individual fused beads. The spaces between the individual fused
beads make the portions 26 and 28 breathable in the sense that air
will move through them, thereby providing ventilation through the
cushion to the user. In addition, the base portion 28 may be formed
somewhat more rigidly and having less flexibility than the human
interface portion 26, to add structural stability to the cushion
20. The human interface portion 26 may be somewhat more flexible to
accommodate interaction with the user's anatomy. The differences in
flexibility and rigidity may be accommodated by using different
sizes and resiliencies of plastic beads and different degrees of
compaction of those plastic beads when fusing them together, as
described in U.S. patent applications Ser. Nos. [249.301 and
249.303].
[0060] The human interface portion 26 and the base portion 28 may
be permanently connected or held together with an adhesive.
However, due to the interlocking structure 52 shown in FIGS. 2-4,
the portions 26 and 28 may also be held together by a
closely-surrounding or encasing covering 30. Holding the portions
26 and 28 together in a nonpermanent manner allows each of the
individual portions 26 and 28 to be changed as necessary to
accommodate changing needs of the user and changes in preferences
for seat support structures.
[0061] The covering 30 can be any type of impervious material, if a
liquid resistant seat cushion 20 is required. However, to take
advantage of the breathable characteristics of the portions 26 and
28, the covering 30 is preferably a fabric or some other type of
material which allows air to pass through it.
[0062] The chart shown in FIG. 11 illustrates the
interchangeability of the human interface portions 26 and the base
supports 28 with different wheelchair seat support structures. The
different types of human interface portions discussed above are
generally represented by the left-hand column in FIG. 11. These
types of human interface portions 26 each include a different
variation of the support contour 32 (FIGS. 2 and 4). Those standard
variations are represented by a female variation support contour
90, a male variation support contour 92, and a non-gender-specific
contour 94 which is intended to accommodate greater degrees of
tissue atrophy. All of these support contours have been discussed
generally above. The human interface portion 26 may also use a
custom support contour 96 which is configured to interface
specifically with the anatomy of a particular individual, as also
discussed above. The right hand column in FIG. 11 represents the
different types of configurations 34 of the base portions 28 which
may be used to accommodate the different types of common wheelchair
seat support structures or which may be part of the wheelchair seat
support structures. Those types of different seat support
structures include the platform seat 36 (FIGS. 1 and 5), the sling
seat 38 (FIG. 6), the dropped platform seat 40 (FIG. 7), the pan
seats 42 and 44 (FIGS. 8 and 9) and the shell seat 46 (FIG.
10).
[0063] By using the human interface and base portions 26 and 28 in
connection with any of the seat support structures 22 in the manner
described, the resulting seat cushion 20 provides support for the
wheelchair user while offering a high level of relative protection
to the wheelchair user against pressure ulcers. Simultaneously, the
needs and preferences of the user are accommodated with respect to
a particular type of seat support structure on a particular type of
wheelchair. These benefits are obtained without the need for
additional hardware and attachment accessories that add to the cost
of the cushion and the weight of the wheelchair. Moreover, the
modularity and interfitting relationship of the seat cushion offers
a relatively inexpensive and effective way to provide a highly
functional seat cushion which closely approximates the benefits of
a custom seat cushion. For those users who require or desire a
custom seat cushion, the custom human interface portion may still
be interconnected with a standard base portion to obtain the
benefits of standard base variations. A relatively few variations
of human interface portions 26 and base portions 28, represented in
FIG. 11, will accommodate the substantial majority of the seat
support structures which are commonly and prevalently available for
use by wheelchair users.
[0064] Most of the same improvements are applicable to use of the
present invention for seat cushions in environments other than
wheelchair seat cushions, for example chairs used in office
environments. A desired type of human interface portion 26 may be
selected according to the preferences of the user, and the type of
base portion 28 is selected according to the type of seating
structure upon which the user prefers to connect the human
interface portion 26. In this manner, the benefits of the human
interface portion for supporting the user are available on a
variety of different types of seating devices and structures. Many
other advantages and improvements will be apparent upon
comprehending the full significance of the present invention, not
only for use with wheelchairs but for other applications as
well.
[0065] Presently preferred embodiment of the invention and many of
its improvements have been described with a degree of
particularity. This description is of preferred examples of
implementing the invention, and is not necessarily intended to
limit the scope of the invention. The scope of the invention is
defined by the following claims.
* * * * *