Chairs and seats – Back movement resiliently opposed in operating position – Back and seat adjust simultaneously
Reexamination Certificate
2000-10-20
2002-02-26
Nelson, Jr., Milton (Department: 3636)
Chairs and seats
Back movement resiliently opposed in operating position
Back and seat adjust simultaneously
C297S300100, C297S284400, C297S284700
Reexamination Certificate
active
06349992
ABSTRACT:
BACKGROUND
The present invention concerns seating units having a reclineable back, and more particularly concerns seating units having a reclineable back and a forwardly movable/tiltable seat that moves with a synchronous movement as the back is reclined.
Manufacturers are becoming increasingly aware that adequate lumbar support is important to prevent lower back discomfort and distress in workers who are seated for long periods. A problem is that the spinal shape and body shape of workers vary tremendously, such that it is not possible to satisfy all workers with the same shape. Further, the desired level of firmness or force of support in the lumbar area is different for each person and may vary as a seated user performs different tasks and/or reclines in the chair and/or becomes fatigued. In fact, a static lumbar support is undesirable. Instead, it is desirable to provide different lumbar shapes and levels of support over a work day. Merely providing a particular shape or an adjustable lumbar support is not enough since seated users are constantly changing their position in the chair. Instead, the chair back must move and flex in a sympathetic manner that mirrors the movement of a human spine and lower back while providing good postural support in all body positions. Accordingly, an adjustable lumbar system is desired that is constructed to widely vary the shape and force of lumbar support. At the same time, the adjustable lumbar system must be simple and easy to operate, easily reached while seated, mechanically non-complex and low cost, and aesthetically/visually pleasing. Preferably, adjustment of the shape and/or force in the lumbar area should not result in wrinkles in the fabric of the chair, nor unacceptable loose/saggy patches in the fabric, even while the range of shape and force adjustment is increased.
A synchrotilt chair is described in U.S. Pat. No. 5,050,931 (to Knoblock) having a base assembly with a control, a reclineable back pivoted to the control, and a seat operably mounted to the back and control for synchronous motion as the back is reclined. This prior art chair incorporates a semi-rigid flexible shell that, in combination with the chair support structure, provides a highly-controlled postural support during the body movements associated with tasks/work (e.g., when the back is in an upright position) and during the body movements associated with recline/relaxation (e.g., when the chair is in a reclined position). This prior art chair moves a seated user's upper body away from the user's work surface as the user reclines, thus providing the user with more area to stretch. In fact, moving around in a chair and not staying in a single static position is important to good back health in workers whose jobs require a lot of sitting. However, users often want to remain close to their work surface and want to continue to work at the work surface, even while reclining and relaxing their body and while having continued good postural support.
Modern customers and chair purchasers also demand a wide variety of chair options and features, and a number of options and features are often designed into chair seats. However, improvement in seats is desired so that a seated user's weight is adequately supported on the chair seat, but simultaneously so that the thigh area of a seated user is comfortably, adjustably supported in a manner that adequately allows for major differences in the shape and size of a seated user's buttocks and thighs. Additionally, it is important that such options and features be incorporated into the chair construction in a way that minimizes the number of parts and maximizes the use of common parts among different options, maximizes efficiencies of manufacturing and assembling, maximizes ease of adjustment and the logicalness of adjustment control positioning, and yet that results in a visually pleasing design.
Accordingly, a chair construction solving the aforementioned problems is desired.
SUMMARY OF INVENTION
In one aspect on the present invention, a seating unit includes a base assembly having a seat-supporting structure, a seat supported on the base assembly, and a back frame pivoted to the base assembly for movement between upright and reclined positions. A compliant back is connected to the back frame in at least one top connection and to one of the back frame and the seat at bottom connections vertically spaced from the at least one top connection. The bottom connections are located proximate a rear of the seat and in front of a bottom of the compliant back so that the bottom connections define an axis that is adapted to be generally aligned with an area associated with a seated user's hip bone and lower spine. The compliant back is flexible so that the compliant back undergoes controlled flexure between the top and bottom connections upon flexure of a seated user's back. The seat has a front portion slidably supported on the seat-supporting structure of the base assembly and a rear portion pivotably connected to the back frame so that the seat moves forwardly in a synchronized motion with the back frame during recline of the back frame.
In another aspect on the present invention, a seating unit includes a base assembly, and a back frame pivoted to the base assembly for movement between upright and reclined positions. A compliant back is operably attached to the back frame at a top connection and operably attached to the back frame at bottom connections. The compliant back includes a forwardly-extending flange generally located along its lower edge forming an axis of rotation at the bottom connections. The axis is located proximate a rear section of the seat and in front of the compliant back. The compliant back includes a thoracic portion, a pelvic portion, and a flexible lumbar portion constructed so that when a seated user flexes his/her lower back rearwardly, a pelvic portion of the compliant back moves pivotally downwardly and rearwardly about the axis, the lumbar portion of the compliant back flexibly moves generally rearwardly to form a more planar arrangement with the pelvic portion, and a thoracic portion of the back pivots about the top connection. By this arrangement, the compliant back, in combination with the back frame and base assembly, is adapted to provide postural support for a seated user's back that is comfortable and yet posturally supports significant flexing and moving of the seated user's torso and spine.
In a seating unit having a base, a seat, a back frame rotatably attached to the base, and a first energy mechanism operably connected to the back frame and the base for biasing the back frame toward an upright position, an inventive improvement includes a compliant back that is flexibly bendable to define different curvilinear shapes for sympathetically supporting a seated user's back, and a belt bracket with forwardly-extending flanges pivotally connecting the compliant back to the back frame at a first connection. The compliant back includes a second connection pivotally connecting the compliant back to the back frame at a second location spaced vertically from the first connection, such that the compliant back is constrained to move over a range limited by the first and second connections. A second energy mechanism includes a force generating mechanism located generally at one of the first and second connections and constructed to bias the bracket and so as to bias a lumbar portion of the compliant back forward with respect to the seating unit.
In another aspect on the present invention, a seating unit construction includes a base assembly, a seat, and a back frame pivoted to the base assembly for movement between upright and reclined positions. A compliant back is pivoted to the back frame at a fixed top connection and includes forwardly-extending flanges pivoted to one of the back frame, the seat, and the base assembly at bottom connections. The bottom connections are spaced forwardly from a lower front central surface of the compliant back, so that, upon flexur
Dammermann Arnold B.
DeKraker Larry
Ekdahl Kevin A.
Heidmann Kurt R.
Klaasen, II Gardner J.
Jr. Milton Nelson
Knoblock Daryl
Price Heneveld Cooper DeWitt & Litton
Steelcase Development Corporation
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