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An ergonomic chair including a seat support structure with a seat and seatback supported by the seat support structure. The seat of the chair is shortened to accommodate the buttocks and ischia, with no weight-bearing on the thighs. The seat back is characterized by an upper portion which protrudes forward greater than the lower portion with a sudden transition to provide an innate lumbar support. Arm rests, if present, do not protrude forward of the seat. A standard seat will have a seat of 12 inches, seat back transition 1.5 inches in depth and 4 inches in height. The chair may be constructed with different measures -and ratios to accommodate differences in size and shape of potential users.

Buis, Sharon G. (Juneau, AK, US)
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International Classes:
A47C1/024; A47C7/02; (IPC1-7): A47C1/024
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Primary Examiner:
Attorney, Agent or Firm:
Sharon G Buis (Juneau, AK, US)
1. A chair comprised of a seat support structure, a seat, a seat back, and optional arm rests. The chair is characterized by: a) The seat is of a length to support the ischia and buttocks with no weightbearing through the thighs. b) A seatback with the superior portion protruding forward greater than the inferior portion. The transition from the superior to inferior portion is sudden. c) Arm rests, if present, do not protrude forward of the seat. The chair of claim one is built without modification to current chair making technology or materials beyond those modifications described in the claim. A standard size chair of claim one has a seat of 12 inches. The seat back height is variable with the transition occurring at 4 inches above the seat, and with an anterior-posterior depth of 1.5 inches at the transition.


This invention claims the benefit of my earlier filed provisional patent, application No. 60/553,035 filed on Mar. 15, 2004.

The title of the invention is ‘KareChare’. It is an ergonomic modification to standard chair design developed by Sharon G. Buis, a Canadian citizen residing in Juneau, Alaska.

There was no federally sponsored research or development involved with this invention.


1. Field of the Invention

The present invention relates to chairs and in particular to a task chair to support a user in an ergonomically beneficial manner.

2. Description of Related Art

Chairs commonly used involve a seat of such length, average 17 inches, but often up to 20 inches or more, such that the user bears weight on the buttocks and ischia as well as the thighs. (When is the last time you considered sitting on your thighs? . . . So, why do we?) Such a design puts pressure on the user's leg, affecting circulation to the legs and feet, and creating discomfort for the user. The lumbar spine is encouraged into a position of extreme flexion known to create disc pathology, another source of much pain and lost work time.

The user may attempt relief by shifting the hips forward into a sacral sit position in which weight is borne through the apex of the sacrum and through the tailbone. While this position relieves strain on the thighs and calves, it also creates a more extreme flexion strain of the lumbar spine.

An alternate solution often used is the lumbar roll. A look at any anatomical chart or specimen by layman or professional alike reveals an acute angle of the lower lumbar spine at L5-S1. The lordotic angle of the mid to upper lumbar spine is much more gradual. A lumbar roll provides a uniform angle for the whole lumbar spine thus providing either too sharp an angle for the upper and mid lumbar spine or too obtuse an angle for the lower lumbar spine.

Should a user find comfort and good bio-mechanics sitting in a standard task chair, yet remains the difficulty in sustaining it while working at a desk. In a standard task chair it is necessary to lean forward to work at a desk thus losing the benefit of the lumbar support available. This option places the user's upper body in a position of strain contributing to headaches, shoulder, neck and mid-back pain, and double crush injuries contributing to carpal tunnel syndrome. The user may alternately choose to sit at the edge of the chair abandoning the lumbar support altogether. Most users lack the ability to sustain an unsupported upright position for any prolonged period thus leaving the user's upper body in a position of strain such as previously described.

The KareChare provides relief for all of the above common seating maladies. The shortened seat removes pressure from the thighs. Circulation is not compromised and the user is not encouraged into lumbar flexion by pressure on the posterior thigh. The user is relieved of the need or option of sacral sitting by the shortened seat.

The transitioned seat back provides an innate lumbar support with an acute angle for the lower lumbar spine and more graduated angle for the mid to upper lumbar spine. Accommodation to the natural curves of the spine allows the user greater comfort and decreased lumbar strain than standard task chairs.

The shortened seat and arm rests allow the user to ‘belly up’ to a desk without loss of the lumbar support. The ‘belly up’ position negates the need to lean forward to work at a desk thereby reducing or abolishing strain to the upper body.

Furthermore, any attempt to modify seating as we know it, should take into consideration the social value of the chair. Sitting in a chair is valued as an adult and civilized behavior in Western societies. The boss sits in a wide chair with a high back, often of leather while supportive staff sit in low backed chairs, which are narrower and usually not of leather. (Ref “The Chair” by Galen Cranz, W.W. Norton Company Inc, 1998) To remove these options in seating by using a stool, a kneeling chair, or a saddle, a users value system and expectations are compromised. The KareChare leaves all of the expected social variations in place while providing any user with an anatomically supportive, ergonomic chair.


The present invention provides an ergonomic chair which relieves the user of many of the common maladies of seating. This is achieved through a shortened seat, and transitional seat back. Together these characteristics provide an innate lumbar support. Equally shortened arm rests allow the user to work at a desk without leaning forward thus the benefit of the lumbar support is maintained while working. Stress on the upper body is reduced by a more upright working position.

The technology and products used in making the chair are not modified from the standards of chair-making of today. Suggested ratios are provided for a standard chair, but can be modified to accommodate different sizes of users. The modifications suggested are applied to task chairs, but can be applied to any kind of seating device.

It is expected that application of the concepts revealed here for the KareChare for other than a task chair will be covered under the applied for patent.


The drawing provided is a lateral view showing the transitional seat back (A), here with a height of 16.5 inches with the transition of 4 inches in height (B), and 1.5 inches in depth (C). This view also shows the shortened seat, here a length of 12 inches (D).

An armrest is not drawn in, but maximal desired forward protrusion is demonstrated (E.)

The five-wheeled seat post is not part of the invention but is shown to complete the image of a chair.

Details on materials, design, and manufacture are not included as these are not part of the concept being applied for patent. The standards of the day are not expected to change with application of the KareChare modifications.

Alternate views are not provided as they failed to demonstrate more fully the KareChare characteristics.