Mattress Overlay With Individual Foam Springs

The invention relates to an overlay for a mattress or other support surface incorporating individual foam springs.

It has been known to provide overlays for mattresses and other support surfaces which include a foam pad with convoluted foam elements. The overlay is placed between the bottom sheet and mattress for support and comfort. When the cushion is used in medical applications, strategic pressure relief may also be obtained. Typical foam mattresses or overlays of the convoluted type are disclosed in U.S. Pat. No. 4,686,725. Other foam pads having convoluted foam elements that are truncated are disclosed in U.S. Pat. Nos. 4,673,452; 4,603,445; and 4,686,724. Various designs of these mattresses are typically constructed on a convoluter machine and the shape of the mattress elements may be determined by interchanging the rings of the convoluter machine. The convoluter machine takes a single blank of foam and cuts two mattress pads out of the blank. The problem arises in that a large amount of foam material is taken out of each individual pad due to the nature of the process. The result is that two convoluted foam mattresses are provided with limited cushioning and support as compared to the original foam blank due to the removal of foam material from each pad. For example, a 2 inch convoluted mattress pad requires a 21/4 inch foam blank, and 2 convoluted pads are produced from the blank. However, only about 50 percent of the foam material of the original 21/4 inch blank is in each pad. Due to this technique, there are considerable void spaces in the convoluted mattress and its cushioning ability is limited. The convoluted material tends to bottom out or flatten when laid upon. If it is desired to truncate the convoluted elements so that they are not as pointed, even more foam material is lost. To compensate, a higher density foam is needed. Since this is expensive, numerous types of filler materials have been used to enhance the cushion and support ability of convoluted pads. Another shortcoming of the convoluted type mattress overlay is that the convoluted elements are significantly interconnected together which makes it practically impossible for the convolutions to effectively act as individual spring elements.

It is also known to saw-out foam material to make mattress overlays. For example, it has been known to saw a foam blank into laterally extending form elements with slots in between. The lateral foam elements are then cut longitudinally and separated. From a cross-sectional view, the lateral elements in the center of the pad are wider than the lateral elements on the ends. Approximately 95 percent of the foam material is left in this type of mattress.

U.S. Pat. No. 4,383,342 discloses a molded mattress construction in which essentially all the foam material put into the product remains.

Accordingly, an object of the invention is to provide a foam overlay which primarily provides maximum support and comfort while secondarily provides maximum redistribution of body weight and pressure.

Accordingly, another object of the invention is to provide a mattress or cushion overlay having individual foam springs in which almost all of the foam material remains in the overlay.

Another object of the invention is to provide a foam overlay and method for a mattress or cushion having a plurality of foam springs which act individually and together as spring elements.

Another object of the invention is to provide a mattress or cushion overlay with individual foam springs which may be used to relieve pressure at strategic pressure points of a patient, in addition to providing comfort and support.

Another object of the invention is to provide a mattress or cushion overlay with individual foam springs which are arranged in such a manner that they act individually without interference from each other and act in groups to support heavier body portions in providing pressure relief and other comfort and support functions for patient and normal bed rest.

The above objectives are accomplished by an overlay which includes hundreds of intricately designed foam springs that have a unique top surface. This provides the correct level of support to different parts of the body by allowing the body to sink into the cushion, and thereby surrounding the body with "ultimate comfort". Each foam spring is about 2 inches wide, 11/2 inches high, and 2 inches deep. There is an approximate 3/8 inch space between each spring on all four sides. This enables the foam spring to cradle each part of the body, and optimize the balance between support and comfort. The top of each foam spring is approximately half the size of its base. This reduces the flatness feeling of the cushion and enables each foam spring to cushion the various weights of each part of the body. Greater comfort is provided than geometrically flay-type cushions. A 3/8 inch channel separates each foam spring throughout the entire surface of the cushion. Optimum air circulation is provided underneath and around to keep the body cooler in summer and warmer in winter. Foam having a 1.4 to 1.5 pound density and 2 inch thickness is used. The density and thickness work in tandem with the special geometrical design to provide the best comfort. Sheets fit perfectly over the cushion and stay in place. The unique cell design and surface allows the body to sink into the cushion just enough for it to conform to the body's shape. Optimum support is provided for areas of the body that normally do not get support such as the small or lower part of the back, neck and shoulders. The overlay cushion provides the correct amount of support to areas of the body that need it, and it floats lighter parts of the body such as the feet. Unlike the convoluted pads, it does not flatten out and thus lose its support. And unlike other foam cushions that have flat surfaces, with the overlay design one does not sleep on top of the cushion, which is like sleeping on a plain, flat mattress. In accordance with the sleeping dynamics of the overlay, every part of the body is cradled with its weight gently dispersed through the special combination of foam content, geometric design, and density. The overlay is made from 100 percent pure polyurethane, and contains no fillers. A high density foam provides the highest level of comfortable support. As contrasted to the convoluted foam pad representing a one dimensional approach to creating comfort, the overlay provides a carefully formulated combination of factors developed to provide heretofore unachievable support and comfort characteristics.

The construction designed to carry out the invention will hereinafter be described, together with other features thereof.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:

FIG. 1 is a perspective view illustrating a foam overlay for a mattress and the like constructed in accordance with the present invention;

FIG. 2 is a partial perspective view illustrating a plurality of foam springs in a foam mattress overlay in accordance with the present invention;

FIG. 3 is a top plan view of individualized foam springs incorporated into a foam mattress overlay in accordance with the present invention;

FIG. 4 is a sectional view taken at the junction of a main support section and a secondary support section of a medical foam mattress overlay constructed in accordance with the present invention;

FIG. 5 is a side elevation illustrating a medical foam mattress overlay constructed in accordance with the present invention for supporting the lower extremities of a medical patient at a lower elevation than a main support section;

FIG. 6 is a perspective view of another embodiment of a foam overlay for a mattress and the like constructed in accordance with the present invention;

FIG. 7 is an enlarged view taken along 7--7 of FIG. 6; and

FIG. 8 is a perspective view illustrating a method for constructing a foam overlay for a mattress and the like in accordance with the present invention.

Referring now in more detail to the drawings, a foam overlay, designated generally as A, is provided for a mattress, cushion, and the like constructed from polyurethane foam such as 1.4 or 1.5 density foam material with an ILD in the 30 to 40 range. For the consumer and normal bed rest, the overlay is constructed having an overall thickness of approximately 2 inches to supplement cushioning and support. Individual foam springs, designated generally as B, have a square cross-section of approximately 2 inches and a height of approximately 11/4 inches. Overlay A for consumer use has an overall height of approximately 2 inches. Channels of approximately 1/4 inch are formed in the foam material longitudinally and laterally to isolate each foam spring and provide air circulation. The foam overlay may be used as an overlay for a mattress or a like cushion to supplement the support and cushioning. The overlay may be used as a mattress or cushion by itself. In addition to supporting and cushioning a person's body, the overlay provides redistribution of body weight to reduce pressure at strategic points of the body and reduce the formation of decubitus ulcers in the case of prolonged bed rest when used by a medical patient.

As can best be seen in FIG. 2, overlay A includes a rectangular foam base C on which a plurality of individual foam springs B are carried. Each foam spring includes a rectangular base block 10 and a horizontally planar support surface 12 at a correct level for body support. A converging solid body in the form of a polyhedron 14 extends between base block 10 and planar surface 12. Polyhedron 14 includes 4 trapezoidal planar faces 16 which converge upwardly to planar surface 12. Preferably, the base of polyhedron 14 coextends with the perimeter of base block 10.

As can best be seen in FIG. 3, there are a plurality of longitudinal air channels 20 and lateral air channels 22 surrounding each individual foam spring B. Channels 20, 22 are dimensioned sufficiently so that foam springs B may act individually and together in groups to support, cushion, and relieve body pressure in an effective manner. For example, channels 20, 22 preferably have a width of approximately 1/4 inch while a width in the range of 1/8 to 3/8 inch may be used. Preferably, base block 10 of foam springs B is a 2 inch square. The height of the foam spring for consumer use is approximately 1 to 11/2 inches. In one embodiment, a foam material of 1.4 to 1.5 pounds was used. The combination of geometric design, individualized foam springs, and density of foam material has been found to provide a highly effective foam overlay for cushioning, supporting, and reducing pressure. This combination floats the lighter parts of the body such as the feet while cradling and supporting the heavier parts of the body. Support surfaces 12 provide the correct level of support to the different parts of the body. The channels enable the foam springs to act individually and independently or in groups to support the heavier parts of the body. These individual springs can move in any direction without interfering with each other in a horizontal plane to significantly reduce pressure against the skin. In essence, the body is cushioned and moves with the surface as opposed to being moved against the surface which creates shearing or abrasion pressure on the skin.

FIGS. 4 through 7 illustrate another embodiment A' of the invention for medical patient use. Overlay A' includes an end, secondary support section 30 with foam springs D and a main support section 32 having foam springs B'. Foam springs B' have the same configuration as springs B of overlay A, but are taller. Like elements are denoted by the same number with a prime. Foam springs B' in section 32 are like springs B of overlay A, yet are larger. Springs B' have a preferred height of about 2 to 21/2 inches above base C' which has a preferred height of about 11/2 inches. The preferred total height of overlay A' in main section 32 is about 31/2 inches. Springs B' have a surface 12' about 1/2 to 1 inch above the level support of surfaces 34 of foam springs D, although this height level differential may vary without departing from the advantages. Springs D have lateral surfaces 36 sawed perpendicular to base C', and inclined surfaces 38 terminating in planar support surface 34. Springs D have a preferred height of 1 to 11/2 inches and section 30 then has a height of about 21/2 to 3 inches. As can best be seen in FIG. 7, longitudinal surfaces 40 of springs D are planar and extend from base C' to support surface 34, generally perpendicular. This is due to the method of making the overlay explained more fully below. With a patient 42 properly positioned, the lower extremities, e.g. feet and heels, are lightly supported by secondary section 30 due to the weight of the legs being supported at the calf and upper leg area by the main section 32. This alleviates and redistributes pressure on the troublesome heel, ankle, and other foot portions reducing decubitus ulcers.

In the foam overlays described above, the foam springs B are arranged in parallel, longitudinal and lateral rows 44, 46, respectively. In the case of medical foam overlay A' the foam springs B', D of the main and secondary support sections are arranged in parallel rows 48 and parallel rows 50 extending in first and second dimensions of the overlay. Grooves 52, 54 like grooves 20, 22 of overlay A extend longitudinally and laterally in overlay A'. It is important to note that the springs B, B', D in the respective rows of overlays A and A' occupy a space next adjacent each other so there are no void spaces on the overlay, except for grooves 20, 22 or 52, 54. The springs are arranged next adjacent each other, laterally and longitudinally, in the previously described rows. The foam springs of adjacent rows are in a uniform and immediate juxtaposed arrangement, as can best be seen in FIGS. 1 and 6. There are no alternating void spaces between the foam springs as occurs in convoluted pads. In this manner, the individualized foam springs B act individually and independently next adjacent one another in both dimensions of the overlay to effectively accommodate the support and comfort of the patient with reduced pressure. In particular, the support and pressure accommodation is provided at the sensitive body areas including the scapula, sacrum, trochanter, and heels.

In accordance with the method, as can best be seen in FIG. 8, a blank foam block 60 having a first dimension (width) 62 and a second dimension (length) 64 equal to that of rectangular base C is fed longitudinally to the saw blade 66 of a computer controlled foam saw machine 68 as can best be seen in FIG. 6. Foam block 60 is supported on a turntable 70 so that the block may be rotated 90 degrees about axis 72. Saw blade 66 carried by housing 74 moves vertically and horizontally, and may tilt.

Beginning at one end 60a of block 60, a lateral row 46 of springs B is simultaneously formed by sawing. Lateral surfaces 10a of all base blocks 10 across the row is first formed by sawing. Next, lateral planar faces 16 are formed and then planar support surfaces 12 across first row 46 are formed. The opposing lateral planar faces 16 and sides 10b of the base blocks are formed. Next, lateral groove 22 is sawed across the pad. Lateral sides 10a of a next adjacent row 46 of base blocks 10 are then formed on the next lateral row of foam springs. All of the planar faces 16, top support surfaces 12, next adjacent planar faces 16, and the opposing lateral sides 10b of base blocks 10 are sawed. Another lateral channel 22 is sawed. This process continues along the entire length of the pad until all of the lateral surfaces and channels are sawed for all the lateral rows 46 of foam springs B. Block 40 is then rotated 90 degrees and fed laterally to saw the longitudinal surfaces of springs B and longitudinal channels 20. Longitudinal surfaces 10c and 10d of base blocks 10, faces 16 of polyhedrons 14, and channels 20 are sawed. This sawing is continued across the width of overlay A until all of the longitudinally extending surfaces of foam spring elements B of all longitudinal rows 44 are sawed and formed. Spring elements B and grooves 20, 22 are completed over the entire surface of overlay A. Saw blade 66 drops down and begins sawing of a next below overlay A. Blade 66 starts at a line 78 corresponding to the bottom surface of rectangular base C of a previously sawed overlay A. As the next overlay A is sawed, the bottom surface of the previously sawed overlay is formed by the sawing of springs B and grooves 20, 22 of the next overlay.

In the method of making medical overlay A', all the cuts in block 60 are formed first in the longitudinal direction instead of the lateral direction as described above. The longitudinal surfaces, support surfaces 12', and longitudinal grooves 52 are formed over the entire area of base C'. Next, the block is sawed in the longitudinal direction. The longitudinal surfaces of springs B' and lateral grooves 54 in main section 32 are sawed. Then, the saw is lowered 1/2 to 1 inch to saw spring D of secondary section 30 which is about 9 inches in length. When saw blade 66 drops down at lateral groove 54a, it cuts the tops and longitudinal inclined surfaces 16' of spring B', previously formed in section 30, off. This leaves the barn-shaped springs D', as can best be seen in FIG. 7. This cut-off is shown in dotted lines 80 in spring B' preceding groove 54a, for illustration purposes only. This is necessary in order to form the lower springs D of section 30.

While any suitable saw 66, 68 may be used, a computer contour saw manufactured by Fecken-Kirfel American, of 6 Leighton Place, Mahwah, N.J. 07430, as Model No. C428207 is particularly advantageous.

While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.