Back cushion

A cushion for engaging the small of the back when the user is in a seated position has a generally planar base portion for engaging a seat back and a generally arc-shaped small of the back engaging portion with dorsal and sacral engaging sections thereon. The back cushion minimizes tension and provides proper curvature for the small of the back section of the spine.

BACKGROUND OF THE INVENTION 
This invention relates generally to the art of back cushions and more 
particularly to the art of a back cushion adapted to minimize unnatural 
curvature of the spinal section between the sacral and dorsal areas of the 
spine. 
Many prior art devices have attempted to provide for increased comfort 
within the small of the back portion of a human being in the sitting 
position. Many such devices are described within prior patents. 
One such spinal support is described in U.S. Pat. No. 1,667,626 to Epstein. 
The spinal support described therein comprises a cushion having a back 
engaging portion substantially of a constant curvature and comprises 
handles for suspending the spinal support in an appropriate position from 
the top of a chair back. 
Another such pad for a chair or seat back is described in U.S. Pat. No. 
1,937,920 to Smith. Smith describes a support which extends from the seat 
area behind the buttocks of the sitting person into the small of the back. 
The back area within the small of the back is engaged by a surface of 
substantially constant curvature. The pad is adapted to be inverted to 
accommodate various size persons with the pad being positioned and 
retained upon the chair seat. 
Another such back rest is described in U.S. Pat. No. 1,975,586 to Law. The 
back rest described therein is intended for use within a moving vehicle, 
such as automobiles and trains. The pillow is adapted for the circulation 
of air so as to minimize the accumulation of heat between the pillow and 
the user. The back rest is generally elliptical and is useful as a head 
cushion as well as a back rest. 
While many such back rests or supports have been available within the prior 
art, no back rest device has been totally satisfactory for the proper 
positioning of the spine so as to minimize tension and unnatural curvature 
which may be caused by excessively long periods within such a sitting 
position and vibrations which may accompany transportation in a moving 
vehicle. 
SUMMARY OF THE INVENTION 
It is thus an object of this invention to provide a cushion for engaging 
the small of the back so as to minimize tension and unnatural curvature 
when in the sitting position. 
It is a still further object of this invention to provide such a cushion 
which is adaptable for use by various sized individuals without 
sacrificing the proper positioning of the back engaging portion. 
These as well as other objects are accomplished by a cushion for engaging 
the small of the back having a generally planar base portion, and a 
generally arc-shaped small of the back engaging portion with dorsal and 
sacral engaging sections thereon.

DETAILED DESCRIPTION 
As used within this disclosure, the term "small of the back" includes that 
section of the spinal column extending from the sacral region through the 
lumbar region and into transition of the dorsal region. The cushion in 
accordance with this invention is adapted for engaging the small of the 
back between that section of the spinal column and a seat back when the 
user is in the sitting position so as to prevent unnatural curvature 
within the small of the back section of the spine and to prevent tension 
within that section of the spine during prolonged periods in the sitting 
position. 
FIG. 1 of the drawings illustrates an oblique view of a cushion in 
accordance with this invention. The cushion has a generally planar base 
portion 1 merging with a generally arc-shaped small of the back engaging 
portion 3. The back engaging portion comprises a sacral engaging section 5 
and a dorsal engaging section 7. Both the sacral engaging section 5 and 
dorsal engaging section 7 merge with the generally planar base portion 1 
to define the upper and lower limits of the cushion. The arc-shaped back 
engaging portion 3 comprises between the dorsal engaging section 7 and 
sacral engaging section 5 a central section 9 of substantially constant 
curvature. 
FIG. 2 of the drawing illustrates in cross section the use of the cushion 
in cooperation with the spinal column and a seat back. As is shown in FIG. 
2, proper spinal curvature is maintained when the cushion of this 
invention is lodged between the spinal column and a seat back. The 
curvature of the generally arc-shaped small of the back engaging portion 
of this invention is best illustrated in FIG. 3 of the drawings, wherein 
the geometrical configuration is illustrated. 
As is shown in FIG. 3, the central section 9 of the generally arc-shaped 
small of the back engaging portion extends through the dimension "A" at a 
constant radius "r". The dimension "A" within the concept of this 
invention may comprise up to 75 percent of the overall height of the 
generally planar portion 1. The dorsal engaging section 7 and sacral 
engaging section 5 are preferably of equal dimensions c and d, but both 
may be varied from about 12 to about 20 percent of the height of base 
section 1. The variation in curvature within the dorsal and sacral 
engaging is readily illustrated in FIG. 3 of the drawing. 
Within the sacral engaging portion 5 the radius expands from the 
substantially constant radius within the central section to a gradual 
tapering to merge with the generally planar base portion 1. 
Within the dorsal section 7 the radius varies initially from the transition 
point 11 to a radius of less than the substantially constant radius "r" 
and then expands to a greater radius at the point of merger with the 
generally planar base portion 1. The section of reduced radius between the 
point of transition 11 and merger with base portion 1 at point 13 produces 
a concavity in the otherwise generally convex surface of the generally 
arc-shaped small of the back engaging portion 3. The dorsal engaging 
section 7 is designed with appropriate curvature to conform the transition 
from the lumbar region of the spinal column into the dorsal region, 
wherein the natural curvature of the spine changes the direction of its 
radius. 
In actual use as is illustrated in FIG. 2 of the drawings, the cushion of 
this invention is lodged between the spine and the seat back. The sacral 
engaging section does not reside behind the buttocks and does not contact 
the seat bottom. The entire cushion is trapped between the spine and the 
seat back so as to provide for support within the small of the back 
regardless of the distance between the seat and the small of the back of 
the individual user. The more preferred use of the cushion in accordance 
with this invention is within an automobile where lengthy trips normally 
severely fatigue the spine and cause unnatural curvature thereof and 
accompanying ailments. During extended travel the support provided by the 
cushion so as to maintain the normal curvature of the spine prevents 
tension within that area as well as providing the support to maintain a 
natural curvature. 
As many of the dimensions within the cushion of this invention are 
significant parameters to the maintenance of proper spinal curvature when 
in a sitting position such dimensions are given herewith. The radius "r" 
is preferably approximately 15 centimeters. The dimension for the height 
of the planar base (a+c+d) is also 30 centimeters. The dimension "A" is 20 
centimeters, with the dimensions "C" and "D" being preferably 5 
centimeters each. The dimension "B" is 9 centimeters. Such dimensions are 
given for purposes of illustrating the preferred construction, and are not 
to be construed as limiting in nature. Such dimensions may be 
significantly varied but are within the scope of this invention as long as 
the cushion adapts and conforms to the curvature of the spine as taught 
herein. For example, the substantially constant radius may be varied 
within the range of 11 to 17 centimeters in order to provide various size 
cushions for various size individuals. 
Conventional foam rubber is the preferred material of construction in 
accordance with this invention. However, such foam rubber may be 
reinforced with metallic or a wire like reinforcement in order to provide 
enhanced rigidity. Additionally the cushion may have embedded therein or a 
cover thereon which includes heating means to provide therapeutic heat 
when the cushion is in use. The cushion may be covered with any desired 
fabric or covering material. For example, when used within an automobile, 
the cushion may be covered with a fabric keyed to complement or blend with 
the fabric or upholstery within the automobile. 
Preferably the cushion in accordance with this invention is of a length to 
permit use by only a single individual. Such a length is generally 
approximately 30 centimeters. It is envisioned, however, that a length of 
substantially the width of an automobile bench seat may be utilized and 
have sufficient flexibility to permit adjustment between passengers. 
It is thus seen that the cushion in accordance with this invention provides 
support for the small of the back for a user in the seated position and 
maintains proper spinal curvature for the user during prolonged periods 
within the seated position. It is additionally seen that the cushion in 
accordance with this invention minimizes tension and unnatural curvature 
within the small of the back and provides critical curvature necessary to 
the maintenance of natural spinal curvature. As many variations will be 
apparent to those of skill in the art from a reading of the above 
specification which is exemplary in nature, such variations are included 
within the spirit and scope of this invention as is measured by the 
following appended claims.