Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Reexamination Certificate
1998-08-18
2001-09-04
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
C428S131000, C428S136000, C428S137000, C428S155000, C428S167000, C428S172000, C428S174000, C428S178000, C428S182000, C428S188000
Reexamination Certificate
active
06284346
ABSTRACT:
U.S. PATENT DOCUMENTS
1,887,310
11/1932
King
2,194,364
3/1940
Minor
2,290,615
6/1942
Firestone
2,433,012
12/1947
Malicovitz
2,785,739
3/1957
McGregor
2,860,768
11/1958
Smithers
3,047,282
7/1962
Hardy
4,222,053
9/1980
Brogan
4,267,782
5/1981
Sakuraoka
4,756,266
7/1988
Sakuraoka
5,054,414
1/1992
Yamaguchi
5,083,335
1/1992
Krouskop
4,574,101
3/1986
Tricca, et. al
4,713,854
12/1987
Graebe
BACKGROUND OF INVENTION
The present invention relates to the production of a cushion or stock material with a predetermined internal structure to achieve desired compression properties from otherwise firmer but compressible or elastomeric material. The invention is best illustrated in the difficult application of an orthopedic cushion such as a mattress.
To support a body orthopedicly, it is generally accepted that a “constant force” cushion should produce a minimal constant support force over as large an area of the body as possible with a corresponding minimum of additional force applied to broadly heavier regions (or protrusions) and lesser forces on lighter regions.
These conditions should result in a minimum of force applied where body regions are minimally sheered by differing amounts of support force and where necessary support force is applied to body concavities. The ideal cushion should achieve this without sagging over time or under excess weight and thus provide body alignment and a defined stop zone for the constant force motion.
Constant force cushions are, however, somewhat difficult to achieve in practice because common springs or foams produce increasing force with compression; and, even bladder structures such as air or water beds typically have surface effects from the bladder itself, rather than constant pressure within, which shift forces toward body protrusions and away from body concavities. Inflexibility or inelasticity of support surface layers can also prevent support forces from filly reaching body concavities such as the lower back. And, finally, mattress type constructions can suffer from “sag” over time or if improperly weighted or inflated.
In beds and other elastomer cushions, attempts to alter material properties have centered principally on foams, their microcell properties and elasticity with even the best foams having only slightly elongated force curves and generally heavier (hence more costly) formulations.
Various bed and cushion applications have employed cavities in foam or rubber materials but these generally suffer from increasing force curves, insufficient support efficiency, unevenness of support or difficult fabrication requirements. Such cavity modification has also not been applied to generalized plank stock for multiple use such as in packaging materials with lighter and more efficient closed cell foams.
There is, therefore, a need for a light weight cushion material with controlled range of force and motion and one which may obtain varied force properties along it's length to accommodate heterogeneously weighted bodies and comes “ready to use”.
It is the object of this invention to provide such a cushion or stock material which may obtain a range of short, elongated or constant force curves, limited surface effects and a controlled range of motion and forces along it's length. It is a further object of this invention to produce a cushion material of lighter weight, orthopedic quality including both support and ventability and one which requires minimal assembly or cutting after initial production. It is also an object of this invention to provide a structure for producing flatter constant force curves which can be formed from any number of foams, elastomers, plastics or spring steel and, in particular, very lightweight and water proof closed-cell foam. Finally it is an object of this invention to introduce a general extruded closed-cell-foam cardboard stock material and several general uses for such.
SUMMERY OF INVENTION
To meet constant force cushioning requirements the present invention employs a truss like cross section. Members of the truss form a plurality of improved a-spring units where the tops and bottoms of the members are symmetrically elongated and co-joined or raised and buttressed.
These features improve upon Sakuraoka [4,267,792, 4,756,2661 and Yamaguchi [5,054,414] by reducing the effective buckling length of support members, preventing the unnecessary outward (lateral) buckling of support members, insuring relatively high initial support and allowing force consistency during collapse. The result is an efficient load distributing system and a cushion of more “constant force” quality with similarly improved shock absorption properties.
Raising the ends of support elements also produces extended folding of the spring elements through the compression cycle into complete thirds or a full sigmoid (up down up) or (down up down) pattern. This extended folding improves the range of motion and potential support element density over non-sigmoid folding such as in King [1,887,310] and Zalicovitz [2,433,012].
The support elements may also be shortened or placed closer together to minimize the “bottoming out” effect when compression extends beyond the generally constant force range. The bottoming out effect also eliminates potential “mattress sag” and thus provides a plane of body alignment in mattress like applications.
The controlled sigmoidal folding process improves over prior art such as King [1,887,310], Minor [2,194,364], Firestone [2,290,615], Hardy [3,047,282] and Krouskop [5,083,335] allowing support elements to collapse with improved mechanical efficiency while folding compactly and uniformly to form a more comfortable support surface under full compression.
The support units may also be constructed without a surface layer (
FIG. 2
) in which case the resulting cushion bares topographical similarity to Smithers [2,860,768] but where the material is uniquely pre-stretched along one lateral dimension and accordingly shaped to produce controlled “sigmoid” folding rather than simple uncontrolled buckling as in King [1,887,310], Firestone [2,290,615], Smithers (2,860,768] and Krouskop [5,083,335].
It should be clear that any number of elastomers or flexible materials can accomidate the described folding or collapsing truss cushion structure. For orthopedic uses such as a light weight, low cost, portable or water proof mattresses, seat cushions or aircraft seats a resilient, springy, low-set, low-creep closed-cell foam will produce the best performance per weight. A similarly low-set open or semi-open-cell foam will produce generally lesser forces for a given base material but firmer plastics, rubber or rubber-like materials are also possible. For shoes or high force applications a stiff solid elastomer may be more applicable. Choice of materials may be performed empirically or calculated through standard engineering means.
In non-constant force applications, such as a general packaging or plank stock material, a traditional closed cell foam may be too firm as cushioning material. The present invention also applies to the use of more generalized corrugated form to improve the cushioning ability in a planer closed cell foam stock by increasing compressibility through a series of cavities along an extruded axis. In non-constant force applications any regular series of cavities or support elements will suffice to create a class of corrugated closed cell stock. These may be classed as either compressing, collapsing or mixed profiles. Compressing profiles have members which do not significantly fold and produce delayed force curves while collapsing profiles produce flatter curves and can produce efficient collapse to a compact shape with little or no cavity space remaining and constant force application in the preferred embodiment below.
Use of foam in this application produces a stiff but flexible light weight stock material unique within closed cell foams with greater thickness and compressibility and re
Caesar Rivise Bernstein Cohen & Pokotilow Ltd.
Loney Donald J.
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