Variable density contour chair

[57] ABSTRACT

A chair includes a cushion of relatively low density flexible material that captivates specially positioned blocks of relatively high and intermediate density flexible material in a manner to improve comfort and minimize certain discomforts of sitting.

The relatively high and intermediate density blocks arc arranged in a pattern to coincide with predetermined high and intermediate load bearing regions determined from date derived from measuring a backside area of a person or a group of people.

The load is distributed so that the stronger and more sensitive prone parts of a person are subjected to proportionally greater and lesser amounts of the overall load as compared with conventional cushions of uniformly compressive material or layered materials.

Claims, 3 Drawing Figures

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PATENIED*» 79'5

3.751.111

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3,75 1

VARIABLE DENSITY CONTOUR CHAIR

BACKGROUND OF THE INVENTION

This invention generally relates to chairs and more specifically to a contour chair having sections of different densities arranged in a special pattern to alleviate annoying and harmful pressures.

The concept of contouring chairs in order to make them more comfortable and stylish is well known in the furniture trade. These chairs ordinarily include a supporting framework or shell curved to accommodate the general configuration of a person’s body and a plurality of separate or linked cushions e.g.; see U.S. Pat. Nos. 3,073,649 to De Montfort granted Jan. 15, 1963 and 3,370,885 to Gale granted Feb. 27, 1968.

Moreover the concept of employing materials of different densities in the construction of chairs is known, e.g.; see U.S. Pat. No. 3,000,020 to Lombard et al. granted Sept. 19, 1961, 3,118,153 to Hood granted Jan. 21, 1964 and 3,175,863 to Hood granted Mar. 30, 1965. The construction materials of different densities are layered or stacked in a particular sequence for comfort, shock-absorbing or appearance purposes.

Both common sense and medical studies indicate that certain parts of a persons’s body are best suited to accept pressure and absorb resulting stress. Conventional chairs are constructed to spread the pressures around in a uniform manner which has the adverse result of subjecting relatively sensitive and poor load bearing portions of a person to disproportionate and excessive strain. Such concentrations in the sensitive areas will eventually result in fatigue, discomfort and possible physical harm.

A primary aim of this invention is to provide a chair with flexible sections of different density and load bearing characteristics arranged in a special predetermined pattern in order to enable the overall load to be distributed so that a greater share of the load is borne by the * superior load bearing portions of the person and therefore the weaker portions of the person are subjected to a lesser amount of the load.

SUMMARY OF THE INVENTION

Briefly stated this invention comprehends a variable density contour chair having a supporting shell and a cushion secured to the supporting shell.

The cushion is constructed primarily from a matrix of relatively low density flexible foam material and has a relatively high load bearing region, a relatively intermediate load bearing region and a relatively light load bearing region.

A block of relatively high density flexible foam material is captivated by the low density flexible foam material and positioned within the relatively high load bearing region of the cushion. A block of relatively intermediate flexible foam material is likewise captivated by the relatively low density flexible foam material and is positioned so as to occupy the space constituted by the relatively intermediate load bearing region of the cushion.

The blocks of relatively high and intermediate density flexible foam material are specially shaped to fully occupy the relatively high and intermediate regions and preferably are oriented in side-by-side generally coplanar relationship. · . ,

The cushion has an upper cushion portion with at least a single block of relatively high density foam ma1,111 terial and a single block of relatively intermediate density flexible foam material. The cushion also has a lower cushion portion including at least dual blocks of high density foam material and corresponding dual 5 blocks of relatively intermediate density flexible foam material.

In carrying out the process of this invention data is gathered from measuring the physical shape of a backside area of a person or persons. A chart is prepared 10 from this data and is divided into relatively high load bearing region, a relatively intermediate load bearing region and a relatively low load bearing region. Blocks are fabricated from relatively high density flexible foam material and intermediate density flexible foam mate15 rial. The blocks Of high and intermediate density are positioned in the mold or otherwise arranged in a pattern so that they are located in the high load bearing region and the intermediate load bearing region. A relatively low density flexible foam material is then flowed 20 around the blocks in order to captivate them and fill in the specified contour which constitutes a chair for accommodating a particular person.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous benefits and unique aspects of the present invention will be fully understood when the following detailed description is studied in conjunction with the drawings in which:

FIG. 1 is a perspective, fragmentary and sectional 30 view of a contour chair constructed in accordance with this invention showing variable density sections arranged in a predetermined position or area;

FIG. 2 is a perspective, partially sectional and partially exploded view showing some variable density sections positioned in a mold prior to being confined and permanently set in place; and,

FIG. 3 is a schematic depiction or chart pattern showing a pressure distribution diagram in the lower portion of the chart relating to a particular but hypothetical person and a density diagram on the upper portion of the chart.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT ⁴⁵ Referring now to the drawings for a full description of this invention, FIG. 1 shows a variable density contour chair 10 having a supporting shell 11 that may be fabricated from any durable suitable material such as fibreglass, metal or wood. The supporting shell 11 has ⁵⁰ a head rest section 12, an intermediate backrest 13, a seating section 14 and a pedestal 15. The opposing sides of shell 11 include upright walls 16 shaped to form arm rests 17.

The chair 10 embodies a cushion 20 having an upper ⁵⁵ cushion portion 21 and a lower cushion portion 22. The _#cushion 20 has an outer or exposed skin 24 and a lower or concealed surface 23 that is attached by cement, bonding compound or other securement means directly to shell 11. A longitudinal cross sectional view of cushion 20 is taken to one side of the longitudinal center line 18 of chair 10.

An enveloping mass or matrix 30 of relatively low density flexible foam material constitutes the general body of cushion 20. Matrix 30 surrounds and confines ⁶⁵ a series of relatively intermediate density and also high density blocks of flexible foam material. The relatively high density blocks 31 and 32 are located within the

3,751,111 upper cushion portion 21 and lower cushion portion 22 respectively. The medium density blocks 33, 34 and 35 are located adjacent the shell head rest section 12, the backrest section 13 and seating section 14, respectively and surround the high density blocks. As shall be fully explained the higher density blocks are judiciously and precisely placed within regions of cushion 20 where a person would require increased or additional support.

Referring now primarily to FIG. 2 another relatively high density block 36 is shown aligned symmetrically with block 32. Similarly, additional intermediate density blocks 37 and 38 are shown disposed symmetrically relative to blocks 33 and 35 respectively. An important step in the procedure of fabricating chair 10 involves precisely arranging the blocks in a predetermined pattern within a mold 40. The blocks are laid in this predetermined pattern within a cavity 42 of a lower mold section 41.

In order to carefully conform the external shape of cushion 20 to the physical shape of a particular hypothetical person a plaster cast 45 may be constructed from an impression previously made from a particular back side area of the person. The cast 45 is shown formed with the person’s simulated profile 44. A cross sectional shape of the profile 44 shows a simulated head 46, upper back 47, lower back 48, posterior 49 and upper leg 50 of the hypothetical person.

Alternatively the contour of the person’s body may be formed during the flowing of foam material by way of seating the individual person on a contour liner. The cushion formed is then only suitable for that person whose impression was made.

The particular flexible foam material from which the low density flexible foam material, medium density flexible foam material and high density foam material are constructed can be any suitable plastic or rubber. The material may be a self-skinning type of polyurethane which has relatively superior physical properties of excellent resistance to abrasion, good temperature stability, high tensile strength and good insulation capabilities. When molding articles from this material, the polyurethane foam develops a permanent skin in one operation thereby eliminating the need of multiple steps and laminating procedures. When this type of polyurethane foam is poured in place within mold 40 and cured the resulting article or cushion 20 has an integral exposed skin 24 and a concealed surface 23 permanently adhered to shell 11 of chair 10.

The chair 10 of this invention is constructed to alleviate strain and minimize fatigue by organizing the chair components in a special pattern to distribute the pressure. The cushion 20 and chair 10 can be custom designed to accommodate the particular requirements of a single person or can be designed to accommodate many people within a general range or class.

Body sensitivity to pressure varies from being relatively dull at some body portions to relatively acute at other body portions. The cushion 20 is constructed to distribute pressure in a manner generally inversely proportional to pressure sensitivity, i.e.; greater pressure on parts of the body less sensitive to pressure and less pressure on parts of the body more sensitive to pressure. FIG. 3 will be described in connection with explaining how this invention may be used and operated.

OPERATION

Keeping the above information in mind it can be un4 derstood how the previously described disadvantages of conventional contour chairs and the like are overcome or substantially eliminated by this invention.

Prior to actually constructing a cushion 20 distribution information relative to a certain person or a class of persons is developed and the developed pressure pattern is represented on the lower half of a special chart 55 shown in FIG. 3. The pressure distribution information can be derived by using electrical pressure indicating devices, pressure sensitive paper, a network of strain gauges or any other conventional device. This data is then represented on the lower half of chart 55, captioned “pressure diagram,” in the form of equal pressure curves or isobars. For example, isobars 56 for the back portion of a person shows pressure increasing inwardly to a predetermined maximal pressure isobar 57. In a similar manner isobars 58 for the posterior portion increase across a gradient of pressure towards a predetermined maximal isobar 59.

In various individuals pressure distribution will reach maximal pressure over an area dispersed from the ischial bone or skeleton through the muscle area. In other individuals with less muscle structure such as invalids or dehabilitated persons, the pressure approaches maximal at points under the ischial tuberosity·

The pressure distribution curves indicated on the “pressure diagram” of chart 55 are interpreted and used for dictating whether light density, intermediate density or high density flexible foam material will be utilized in certain regions of the cushion 20.

It will be appreciated that for pressure regions greater than the critical pressures indicated by isobars 57 and 59, relatively high density material 31 a and 32 a will be used. For regions between predetermined minimal isobars and associated maximal isobars the intermediate density material 33 a, 34 a and 35 a will be used. The numerals shown in connection with the upper part of chart 55 captioned “density diagram” correspond with the numerals of FIG. 1 and FIG. 2. When the general outlines for the blocks of high density and intermediate density material are determined then the individual blocks are cut out or otherwise formed into shape for subsequent placement in mold 40 and eventual incorporation in the cushion 20. By way of example the person for whom variable density contour chair 10 is being constructed may be a dehabilitated person requiring a chair with certain physical measurements and contoured impressions. By way of this invention the support points about which the isobars extend or radiate for certain distances can be determined. Pressure point data can be provided by way of instrumented chairs equipped with potentiometers and gauges for example so that eventually a “pressure diagram” is shown in the lower half of FIG. 3 may be developed. Also anthropomorphic data for persons having a general type of stature may be used.

As previously indicated the chair 10 may be completed by having the particular person positioned on a liner located in the mold 40.

From the foregoing it will be evident that the present invention has provided a variable density contour chair in which all of the various advantages are fully realized.