Stock material or miscellaneous articles – Sheet including cover or casing – Foamed or expanded material encased
Reexamination Certificate
2000-11-01
2003-04-01
Morris, Terrel (Department: 1771)
Stock material or miscellaneous articles
Sheet including cover or casing
Foamed or expanded material encased
C428S217000, C428S316600, C428S319300, C428S315900, C442S221000, C442S370000
Reexamination Certificate
active
06541094
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to mattresses and cushions, and more particularly to supports made of visco-elastic material.
2. Related Prior Art
Mattresses and cushions used every day in homes and hospitals are not well-suited for people requiring pressure-relief. In hospitals, for example, long-term patients often suffer from pressure sores.
SUMMARY OF THE INVENTION
Known supports made of standard polyurethane foam do not provide even or well-distributed support of a body reclining thereon because of the polyurethane material. Such known standard supports have a spring-like characteristic that tends to return an increased reactive force in response to increasingly large forces on the support. Moreover, the greater the deflection of the polyurethane support, the greater the reactive force provided by the standard support. This spring-like characteristic is undesirable in the case of long-term patient care because the points at which the greatest pressure occurs are the points at which pressure sores can be formed.
Changing the density of the standard polyurethane foam used in such known supports does not improve the performance of such known supports. For example, use of a lower density foam requires a thicker, bulkier cushion or mattress, which can easily become unwieldy or unstable, and can still result in pressure points because of the inherent spring-like nature of the polyurethane foams. Also, if a sufficiently large force is applied to a support made of low density polyurethane foam, it is possible that the force will “bottom out” or act through the support and onto whatever structure lies below or behind the support.
The present invention therefore seeks to provide improved supports, such as mattresses and cushions, for pressure-relief.
According to the present invention there is provided a laminated support for pressure-relief comprising at least two layers of foam adhered together, wherein at least one layer is a visco-elastic foam.
In one embodiment, the laminated support comprises two layers of visco-elastic foam adhered together, wherein one layer of visco-elastic foam has a greater hardness than the other layer. The laminated support may further comprise a layer of polyurethane foam adhered to the layers of visco-elastic foam.
In another embodiment, the laminated support comprises a single layer of visco-elastic foam and a single layer of polyurethane foam adhered together.
The visco-elastic properties of the laminated support respond to a combination of body weight and body temperature. In particular, visco-elastic foam supports tend to soften when heated, and therefore tend to soften in response to body heat. As a result, relatively hard visco-elastic material will initially firmly support a body lying thereon and will soften at the pressure points. Thus, the support subsequently gently molds to the form of the body, allowing pressure to be absorbed uniformly and distributed evenly across the support. This property is of particular benefit in the prevention and healing of pressure sores.
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Translation of JP-62-183790, Ida et al, Cushion seat, Feb. 7, 1986, 10 pages.*
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Allaway Michael B.
Landvik Dag
Michael & Best & Friedrich LLP
Morris Terrel
Tempur World, Inc.
Vo Nai
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