Variable posture component system seating device

Claims

I claim the following:

1. A multi-task configurable, continuously variable posture seating device, the seating device comprising:

a base;

a height adjustable support means mounted on said base;

a seat portion;

at least one armrest, the armrest having means for accepting a task accessory;

means for pivotally attaching said armrest to said seat portion;

a backrest;

means for tiltably supporting said seat portion on said height adjustable support means; and

means for tiltably supporting said backrest on said height adjustable support means so that independent movement of said seat portion relative to said backrest is provided, and so that the relationship between said seat portion and said backrest may be continuously and independently varied while the relationship between said seat portion and said means for accepting a task accessory remains substantially constant.

2. A seating device according to claim 1, wherein said task accessory comprises an abdominal rest.

3. A seating device according to claim 2, wherein said means for pivotally attaching said armrest to said seat portion comprises:

a shaft having a threaded portion and a portion for attaching to said armrest;

a main member having a hole therein for accepting the threaded portion of the shaft, the main member being fixedly attached to said seat portion; and

means for engaging the threaded portion of the shaft and fixing the relative position between the shaft and the main member.

4. A seating device according to claim 1 further comprising a removable support means for supporting a user's knees and calves, said removable support means being removably attached to said base.

5. A seating device according to claim 4, wherein said base comprises:

a cross member;

a main member that is longer than the cross member, the cross member being rigidly attached to the main member in a position such that the main member substantially bisects the cross member and forms a cross having three arms of substantially the same length, and a fourth arm that is longer than the rest of the arms; and

a short member that is shorter than said cross member and is attached to the fourth arm at a position that permits the fourth arm to substantially bisect the short member.

6. A seating device according to claim 5, wherein the fourth arm of said base further comprises a section of reduced elevation, so that at least part of the portion of the fourth arm that extends beyond the three arms of substantially the same length will have an overall height that is lower than the height of the three arms.

7. A seating device according to claim 1, wherein said means for accepting a task accessory comprises means for accepting an accessory support bar.

8. A seating device according to claim 7, further comprising an abdominal rest removably mountable on the accessory support bar.

9. A seating device according to claim 7, further comprising a desk surface removably mountable on the accessory support bar.

10. A multi-task configurable, continuously variable posture seating device, the seating device comprising:

a base;

a height adjustable support means mounted on said base;

a seat portion;

at least one armrest, the armrest having means for accepting a detachable abdominal rest;

means for pivotally attaching said armrest to said seat portion;

a backrest;

spring biased means for tiltably supporting said seat portion on said height adjustable support means;

spring biased means for tiltably supporting said backrest on said height adjustable support means so that independent movement of said seat portion relative to said backrest is provided, and so that the relationship between said seat portion and said backrest may be continuously and independently varied; and

a removable support means for supporting a user's knees and calves, said removable support means being removably attached to said base, so that independent movement of said seat portion allows alternating use of said removeable support means and said backrest.

11. A seating device according to claim 10, wherein said means for pivotally attaching said armrest to said seat portion comprises:

a shaft having a threaded portion and a portion for attachment to said armrest;

a main member having a hole therein for accepting the threaded portion of the shaft, the main member being fixedly attached to said seat portion; and

means for engaging the threaded portion of the shaft and fixing the relative position between the shaft and the main member.

12. A multi-task configurable, continuously variable posture seating device, the seating device comprising:

a base;

a height adjustable support means mounted on said base and having a vertical axis;

a seat adjustment means pivotably mounted on said height adjustable support means so that said seat adjustment means may pivot about the vertical axis of said height adjustable support means;

a seat portion;

at least one armrest, the armrest having means for accepting a detachable desk surface;

means for pivotally attaching said armrest to said seat portion;

a backrest;

a spring biased means for tiltably supporting said seat portion on said seat adjustment means;

means for tiltably supporting said backrest on said seat adjustment means, so that independent movement of said seat portion relative to said backrest is provided, and so that the relationship between said seat portion and said backrest may be continuously and independently varied.

13. A seating device according to claim 12, wherein said means for pivotally attaching said armrest to said seat portion comprises:

a shaft having a threaded portion and a portion for attachment to said armrest;

a main member having a hole therein for accepting the threaded portion of the shaft, the main member being fixedly attached to said seat portion; and

means for engaging the threaded portion of the shaft and fixing the relative position between the shaft and the main member.

14. A multi-task configurable, continuously variable posture seating device, the seating device comprising:

a base comprising:

a cross member;

a main member that is longer than the cross member the cross member being rigidly attached to the main member in a position such that the main member substantially bisects the cross member and forms a cross having three arms of substantially the same length and a fourth arm that is longer than the rest of the arms, the fourth arm further comprising a section of reduced elevation, so that at least part of the portion of the fourth arm that extends beyond the three arms of substantially the same length will have an overall height that is lower than the height of the three arms of substantially the same length; and

a short member that is shorter than said cross member and is attached to the fourth arm at a position that permits the fourth arm to substantially bisect the short member;

a height adjustable support means mounted on said base;

a seat portion;

at least one armrest, the armrest having means for accepting a task accessory;

means for pivotally attaching said armrest to said seat portion, said means for pivotally attaching said armrest comprises a shaft having a threaded portion and a portion for attachment to said armrest;

a main member having a hole therein for accepting the threaded portion of the shaft, the main member being fixedly attached to said seat portion; and

means for engaging the threaded portion of the shaft and fixing the relative position between the shaft and the main member;

a backrest;

means for tiltably supporting said seat portion on said height adjustable support means;

means for tiltably supporting said backrest on said height adjustable support means so that independent movement of said seat portion relative to said backrest is provided, and so that the relationship between said seat portion and said backrest may be continuously and independently varied; and

a removable support means for supporting a user's knees and calves, said removable support means being removably attached to said base, so that independent movement of said seat portion allows alternating use of said removeable support means and said backrest.

15. A seating device according to claim 14, wherein said means for accepting a task accessory comprises means for accepting an accessory support bar.

16. A seating device according to claim 15, further comprising an abdominal rest removably mountable on the accessory support bar.

17. A seating device according to claim 15, further comprising a desk surface removably mountable on the accessory support bar.

18. A method for continuously varying the support of a person's posture and varying tasks to be performed by the person on a single seating device, the various tasks requiring continuous variation of the person's posture, the method comprising:

providing a base and a height adjustable support means mounted on said base;

supporting the person's buttocks and upper thighs on a tiltable seat while supporting the tiltable seat on the adjustable support means and while pivotally supporting on the seat at least one armrest with means for supporting and varying a task accessory so that the task to be performed by the person may be varied;

supporting the person's back on a backrest that allows independent movement of the seat relative to the backrest so that the supporting of a person's posture may be continuously and independently varied from primarily the seat to combined support using the seat and the backrest while varying tasks; and

providing a knee and calf support means on said base, so that the support of person's posture may be continuously varied from supporting the knee and calf of the person while supporting the buttocks on the seat to supporting the knee and calf while supporting the buttocks and back while varying tasks performed in cooperation with the task accessory.

19. A method according to claim 18, and further comprising the step of cooperatively supporting the posture on an armrest mounted means for abdominal support on at least one armrest so that the person's posture may be continuously varied from cooperatively supporting the posture on the knee and calf support, the seat, and the abdominal support to cooperatively supporting the posture on the knee and calf support, the seat, and the backrest while varying the task.

BACKGROUND

1. Field of Invention

The present invention relates to a variable posture work chair, particularly a component system in use at, or designed to function as, an office, industrial, or home work station.

2. Description of Prior Art

A widespread crisis in the physical aspect of sitting at the modern work station has initiated a variety of so-called ergonomic attempts to solve the problem. Briefly stated, that problem arises out of improper seating posture and the extended immobilization that is required of a worker at a work station, particularly where a keyboard is in use. Worker pain usually manifests itself in the lower back, the legs, the neck, the shoulders and the wrists. Much, although not all, of this pain can be attributed to poorly designed chairs that do not allow the sitter to effect real and meaningful changes in the long term sitting position.

Efforts to solve the problem from the standpoint of seating at the work station can be loosely grouped into five broad categories: conventional office chairs, kneeling posture chairs, forward support chairs, variable posture chairs and dedicated personal work stations. We shall omit from this discussion stools and associated designs that support a person in a standing or near standing position.

"Conventional office chairs" are what we are mostly accustomed to, comprising a base, a seat, a backrest, appropriate mechanisms and, in some cases, rests for the head and arms. Depending upon the design variation, the seat and the backrest may be solidly connected to act as a unit or they may move and/or be adjusted somewhat independently of one another. U.S. Pat. No. 5,056,866 to Tobler shows a conventional office chair incorporating another possible design feature, that of a rocker; Tobler builds his seat and back as a solid unit. It should be noted that the rocker principle can also be used in the above design of independent back and seat movement.

Most office chairs sold are of the conventional variety, improvements to which focus mainly on more and better chair adjustments, better seat design, and provision for lumbar support. The intrinsic drawback here is that the sitter is limited to minor variations on one basic sitting position, that of leaning backward; when the worker leans forward and into his or her work, as most people do, they come into opposition to the chair's basic design, eventually stressing the entire body. In such a chair one typically sits up or forward on the seat for brief periods of time, periodically collapsing against the chair's backrest for relief. Long term sitters resort to unconscious fidgeting, a sign the body is seeking a new position. Even those variations that allow the seat to tilt forward to accommodate the shifted pelvis are extremely limited because they do not provide support for the forward leaning body.

"Kneeling posture chairs" are a group of chairs that typically have a forward tilted seat, an oppositely tilted knee rest(s), and may be mounted on a variety of bases. U.S. Pat. No. 4,328,991 to Mengshoel and Opsvik, U.S. Pat. No. 4,589,699 to Dungan, and U.S. Pat. No. 4,767,159 to Opsvik are examples of this type of seating arrangement. While these chairs offer some improvement by emphasizing a forward tilted pelvis and an erect spine, they have several major drawbacks. First, because of the inclined seat angle and gravitational forces the sitter tends to slide forward and off of the seat, being prevented from doing so only by the knee rest. This design inherently focuses constant pressure directly on the knees, resulting in intolerable pain for many people. Second, while a desirable and ergonomically correct sitting posture would involve relaxing the legs while spreading out any support pressure on them evenly from the knee to the ankle, this inherently focused knee pressure makes such posture impossible. Third, while the design is supposed to promote good posture without upper body support it works only marginally in practice. A person at a work station does not sit eternally erect; one is constantly leaning forward, backward and to the sides, placing stress on the very muscles which maintain erect posture. As these muscles fatigue the sitter begins to slump and the posture actually deteriorates. Fourth, while the basic posture these chairs create is a good starting place, it is the only one they offer; immobility and constriction are serious problems with these chairs and many people abandon them after a few months of use. (One configuration shown in U.S. Pat. No. 4,328,991 does include a backrest and rails to allow a rocking motion; this chair will be mentioned again below as a variable posture design.)

"Forward support chairs" represent an attempt to solve a fundamental problem in work place sitting: that of accommodating the forward lean of the body. U.S. Pat. Nos. 4,650,249 to Serber and 4,943,117 to Brown show non-reversible forward support while sitting; U.S. Pat. Nos. 3,165,314 to Clearman and Webster and 3,754,787 to Garber show additional non-reversible industrial applications of this principle. Supporting the forward lean has certain advantages, but the design is still limited to one basic seating posture; it is also subject to certain of the criticisms of the reversible chairs below.

"Variable posture chairs" are here considered to be any chair that can support at least two distinct changes in body position. The significant advantage of this approach is that the sitter is allowed a complete posture change. We will form two subcategories in this group: reversible chairs and hybrids. Reversible chairs are chairs that can function in a conventional fashion and also be turned around to offer forward support. U.S. Pat. Nos. 454,100 to Wilson, 2,364,050 to Benson, 4,607,882 to Opsvik, and 4,832,407 to Serber show true reversible chairs, wherein the sitter may lean either forward or backward against a vertical plane of support. Variations of this and the aforementioned forward support principles can offer significant advantages at the work station; however, with the possible exception of the dedicated industrial designs all of these chairs also have significant drawbacks. First, since an adequate backrest must be large enough to comfortably spread out the pressure on the rear of the rib cage, reversal offers a large torso/chest support by default rather than planned design, or it compromises both; second, reversal cannot adequately address the real structural and physiological differences between forward and backward leaning; third, it can be argued that abdominal support is, in many cases, a preferable method of forward support; fourth, the torso support is mounted on a center post that comes up directly between the legs; therefore, they must be straddled to get into, and fifth, in the case of the reversible designs a sitter must get up and out of the chair, physically reverse it, and sit back down again to gain the benefit of that design.

These factors make the design singularly unattractive for many people to use in an office environment, and impossible for a woman wearing a dress. The center post mounting of the torso support is a particular nuisance. Several of these design issues also make it extremely difficult for those who may need help the most--the injured and the infirm--to enjoy its benefits.

Hybrids include any variable posture chair not already mentioned. Such chairs generally offer some knee/leg support in the form of a cushioned rest mounted to the chair base of a design that includes a seat and a backrest; the familiar recliner design would be part of this category. In U.S. Pat. No. 4,832,407 Serber has attached a knee rest to the center post of a traditional five star chair base via an extended member; only Serber offers optional forward support within this group. In U.S. Pat. No. 4,765,684 to Kvalheim and Petersen a knee rest is mounted to the center post of a conventional chair base via an extended member which allow