Abstract:
A chair back according to embodiments of the present invention includes a rigid support member for reclinable attachment to a base, a flexible frame member having a flexible frame and a mesh, the mesh at least partially spanning the frame, and a seat attachment member moving in synchronization with the rigid support member at a different rate than the rigid support member during reclining of the rigid support member, wherein a first portion of the flexible frame member is affixed to the rigid support member, wherein a second portion of the flexible frame member flexes freely, wherein the seat attachment member contacts at least part of the second portion of the flexible frame member, wherein the first portion moves with the rigid support member and the second portion moves with the seat attachment member such that a curvature of the second portion increases as the rigid support member reclines.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/894,659, filed on Mar. 13, 2007, and entitled, “Dynamic Chair Back Lumbar Support System,” which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention relate generally to office furniture, and more specifically to a dynamic chair back lumbar support system therefor. 
     BACKGROUND 
     Current reclining chair designs often do not effectively match movement of a user with movement of the chair parts. For example, some chairs feature a reclining seat back coupled with a stationary seat, which does not permit the user&#39;s spine to conform to a natural position when reclining. As a user shifts a chair from an upright to a reclined position, a user&#39;s spine undergoes increased curvature, particularly in the lumbar region, which is often not addressed by chair backs which maintain the same shape throughout reclination. Therefore, there is a need in the art for an improved chair back design. 
     SUMMARY 
     A chair back according to some embodiments of the present invention includes a flexible frame portion configured for attachment to a seat and a rigid support member configured for pivotal attachment to a chair base, wherein a degree of curvature of the flexible frame portion increases dynamically as the rigid support member reclines about the chair base. 
     A chair back according to other embodiments of the present invention includes a rigid support member configured for reclinable attachment to a chair base, a flexible frame member including a flexible frame and a mesh element, the mesh element at least partially spanning the flexible frame, and at least one seat attachment member configured for coupling to a seat, the seat moving in synchronization with the rigid support member at a different rate than the rigid support member during reclining of the rigid support member. According to such embodiments, a first portion of the flexible frame member is affixed to the rigid support member, and a second portion of the flexible frame member flexes freely with respect to the rigid support member, such that the at least one seat attachment member contacts at least part of the second portion of the flexible frame member, and the first portion moves with the rigid support member and the at least part of the second portion moves with the seat attachment member such that a degree of curvature of the second portion increases as the rigid support member reclines. In some cases, the flexible frame is an inverted U-shaped frame. The seat attachment member may be rotatably or rigidly coupled with the flexible frame member; alternatively, the seat attachment member may be formed integrally with the flexible frame member or the seat. The flexible frame may be an outer frame, and the mesh element may be configured to contact a user&#39;s back. The free-flexing portion of the flexible frame member may be configured to provide support to a lumbar region of a user&#39;s back, and may be configured to dynamically adjust to match increasing curvature of a user&#39;s lumbar back region during reclining. A mesh element may be configured to at least partially span the flexible frame portion, and to contact a user&#39;s back. In some cases, the flexible frame portion is configured for attachment to the seat via a seat attachment member, and is configured to dynamically adjust to match increasing curvature of a user&#39;s lumbar back region during reclining. 
     A chair according to some embodiments of the present invention includes a base, a seat pivotably coupled to the base, a back including a rigid support member and a flexible frame member, the rigid support member pivotably coupled to the base, the flexible frame member coupled to the rigid support member and coupled to the seat, and a linkage assembly coupled to the back and to the seat, the linkage assembly configured to rotate the seat at least partially upwardly and at least partially toward the back during reclining of the back about the base, wherein a curvature of the flexible frame member increases as the back reclines about the base. The flexible frame member may be coupled to the seat by a seat attachment member, which may be a spring. The flexible frame member may be pivotably or rigidly coupled to the seat, and a mesh or polymer element may at least partially span the flexible frame member to contact a user&#39;s back, for example. 
     A chair back according to embodiments of the present invention includes a rigid support member configured for reclinable attachment to a chair base, a flexible frame member comprising a flexible frame and a mesh element, the mesh element at least partially spanning the flexible frame, and at least one seat attachment member coupled to a seat, the seat having a substantially fixed position with respect to the chair base, wherein a first portion of the flexible frame member is affixed to the rigid support member, wherein a second portion of the flexible frame member flexes freely with respect to the rigid support member, wherein the at least one seat attachment member contacts at least part of the second portion of the flexible frame member, and wherein the first portion moves with the rigid support member such that a degree of curvature of the second portion increases as the rigid support member reclines. In some cases, the seat attachment member is a spring. The flexible frame member may be pivotably or rigidly coupled with the seat attachment member, which may itself be a part of a core assembly or control assembly, according to embodiments of the present invention. A mesh and/or polymer element may at least partially span the flexible frame member. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a front perspective view of a chair according to embodiments of the present invention. 
         FIG. 2  illustrates a front view of the chair of  FIG. 1 , according to embodiments of the present invention. 
         FIG. 3  illustrates a back view of the chair of  FIGS. 1 and 2 , according to embodiments of the present invention. 
         FIG. 4  illustrates a side view of the chair of  FIGS. 1-3 , according to embodiments of the present invention. 
         FIG. 5  illustrates another side view of the chair of  FIGS. 1-4 , according to embodiments of the present invention. 
         FIG. 6  illustrates a top view of the chair of  FIGS. 1-5 , according to embodiments of the present invention. 
         FIG. 7  illustrates a bottom view of the chair of  FIGS. 1-6 , according to embodiments of the present invention. 
         FIG. 8  illustrates an exploded perspective view of the chair of  FIGS. 1-7 , according to embodiments of the present invention. 
         FIG. 9  illustrates a side view of the chair of  FIGS. 1-8  with an upright position in broken lines superimposed upon a reclined position in solid lines, according to embodiments of the present invention. 
         FIG. 10  illustrates a front perspective view of a chair and back according to embodiments of the present invention. 
         FIG. 11  illustrates a side view of a chair back whose shape changes dynamically throughout reclination, according to embodiments of the present invention. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Embodiments of the present invention relate generally to office furniture, and more specifically to a chair back which changes shape during reclination.  FIGS. 1-7  depict a reclining office chair  100  according to embodiments of the present invention. Chair  100  includes a back  102 , a seat  104 , a left arm  106 , a right arm  108 , and a base pedestal  110 . Seat  104  and back  102  of chair  100  rotate about base pedestal  110 , and casters  112  or wheels may be coupled to base pedestal  110  to contact an underlying surface (such as, for example, a floor), according to embodiments of the present invention. Back  102  may include a support member  116  and a covering (not shown) made of mesh, fabric, polymer, plastic, or the like which is coupled to back  102  along outer frame  114  and against which a user&#39;s back would rest, according to embodiments of the present invention. 
     As used herein, the term “coupled” is used in its broadest sense to refer to elements which are connected, attached, and/or engaged, either directly or integrally or indirectly via other elements, and either permanently, temporarily, or removably. As used herein, the term “swivelably coupled” is used in its broadest sense to refer to elements which are coupled in a way that permits one element to swivel with respect to another element. As used herein, the terms “rotatably coupled” and “pivotably coupled” are used in their broadest sense to refer to elements which are coupled in a way that permits one element to rotate or pivot with respect to another element. As used herein, the term “slidably coupled” is used in its broadest sense to refer to elements which are coupled in a way that permits one element to slide or translate with respect to another element. 
     As used herein, the terms “horizontal,” “horizontally,” and the like are used in their broadest sense to refer to a direction along or parallel to a plane relative to a chair  100 , where such plane is defined by the lines H 1  and H 2  depicted in  FIGS. 2 ,  5  and  6 . Although lines H 1  and H 2  are not shown in all views, the plane defined by H 1  and H 2  in  FIGS. 2 ,  5  and  6  serves to define such plane in all views as such plane is defined relative to chair  100 . As used herein, the terms “vertical,” “vertically,” and the like are used in their broadest sense to refer to a direction along or parallel to a line relative to a chair  100 , where such line is defined by the line V 1  of  FIGS. 2 ,  5  and  6 . Although line V 1  is not shown in all views, line V 1  serves to define such line in all views as such line is defined relative to chair  100 . 
     As illustrated in the side view of  FIG. 5 , back  102  reclines and/or rotates in a direction generally indicated by arrow  502  about a pivot point generally indicated at  506 , when user pushes against back  102 . This rotation of back  102  in direction  502  causes seat  104  to slide generally towards the back  102  in a direction indicated by arrow  504 , as well as generally upwardly. According to embodiments of the present invention, the seat  104  does not move at the same rate as the back  102  during reclination; in other words, the back  102  and seat  104  do not form a simple “L” shape which simply tilts backwardly during reclination. 
       FIG. 8  depicts an exploded view of chair  100  including back  102 , seat  104 , left arm  106 , right arm  108 , pedestal  110 , casters  112 , and core assembly  820 , which are coupled to form chair  100 . Core assembly  820  is coupled with pedestal  110  via a hydraulic piston  826  which permits core assembly  820  to rotate about pedestal  110  and which permits the height of core assembly  820  to be adjusted with respect to pedestal  110 . Sheath  822  may be included between core assembly  820  and pedestal  110  to cover and protect hydraulic piston  826  and/or spring  824 . Spring  824  may be included between core assembly  820  and pedestal  110  in order to supply an upwardly-biased force to raise sheath  822  as core assembly  820  is lifted by hydraulic piston  826 , according to embodiments of the present invention. As used herein, the terms “base” and “chair base” are used in their broadest sense to refer to an element or elements about which the back  102  reclines. According to some embodiments of the present invention, the base of chair  100  may be a component of core assembly  820  about which the other components and/or linkages move or rotate; for example, the base may be the element of core assembly  820  which interfaces directly with the piston  826  and the other elements which are rigidly coupled to such element. In other words, the base of chair  100  may be, in kinematic terms, the “ground link” near the seat to which the other links are coupled, according to embodiments of the present invention. 
       FIG. 9  illustrates a chair back  102  in an upright position  4102  in dotted lines superimposed upon a chair back  102  in a reclined position  4104  in solid lines. Generally, a user&#39;s back undergoes an increasing amount of curvature as a chair back  102  is progressed through an increasing degree of reclination, and/or the user&#39;s back requires greater support in the lumbar region as the chair back  102  is progressed through an increasing degree of reclination. Embodiments of the present invention seek to add to the user&#39;s comfort during reclining by more closely matching movement of chair back  102  to the movement and/or support requirements of a user&#39;s back, and by minimizing misalignment of the user&#39;s back with respect to back  102 . 
     As seen in  FIG. 8 , core assembly  820  includes one or more springs or seat attachment members  832  coupling the back of core assembly  820  to back  102 . Such springs  832  may be rigid or semi-rigid springs, and may be coupled to a seat plate such that their movement follows any movement of the seat  104 , according to embodiments of the present invention. The outer frame  114  may include one or more lower pads  830 . According to some embodiments of the present invention, the seat  104  remains stationary as the back  102  reclines, thereby also creating a curvature of the frame  114  based on the relative motion of the back  102  with respect to the seat  104 . According to some embodiments of the present invention, the frame  114  may be coupled directly or indirectly to a stationary seat  104  and/or to another element which does not move with respect to the back  102 ; for example, the frame  114  may be coupled to a portion of the core assembly  820  which, as the back  102  reclines, has a different relative motion in order to create an increasing curvature of the frame  114  as the back  102  reclines. 
     According to embodiments of the present invention, springs  832  are affixed to a seat plate of the core assembly  820  on one end, and are rotatably coupled to pads  830  at the other end. According to such embodiments, the lower end of outer frame  114  (e.g. pads  830 ) travels along with seat  104  during reclining, which causes the outer frame  114  to exhibit a greater degree of bending and/or curvature during reclining, particularly in chairs  100  in which the seat  104  moves at a different rate from the back  102  during reclining.  FIG. 9  conceptually illustrates the different curvature of outer frame  114 ′ upon reclining to position  4104  when outer frame  114 ′ is rotatably coupled to support member  116  (e.g. via pads  830 ), according to embodiments of the present invention. According to such embodiments, outer frame  114 ′ exhibits a curvature (e.g. in the lumbar region) which increases as the chair  100  is reclined, just as the curvature of a user&#39;s back increases as the user&#39;s back moves with the reclining back  102 . 
     Although embodiments of the present invention illustrate the use of dual springs  832  rotatably coupled with dual pads  830 , other embodiments of the present invention include a single spring  832  rotatably coupled with a single pad  830  and/or directly with the outer frame  114 . Yet other embodiments include two or more springs  832  rotatably coupled with two or more pads  830 , and/or a rotatable coupling directly between seat  104  and/or seat support members and outer frame  114 . According to some embodiments of the present invention, a non-rotatable coupling may be used between outer frame  114  and spring  832 , which still permits movement of outer frame  114  with seat  104  instead of with back  102 . 
       FIG. 10  illustrates a front perspective view of a chair and back according to embodiments of the present invention.  FIG. 11  illustrates a side view of a chair back whose shape changes dynamically throughout reclination as the base is held steady, according to embodiments of the present invention.  FIG. 11  depicts the chair back toward the beginning of reclination, according to embodiments of the present invention. As can be seen in  FIG. 11 , the shape of the outer frame  114  and thus the mesh and/or fabric extending therebetween changes during reclining, to provide increased curvature and/or lumbar support during reclining. A center support member  1210 , such as, for example, a V-shaped support member, may optionally be used to span the left and right sides of outer frame  114  to maintain any desired separation between the left and right sides of outer frame  114  and thus to provide a desired level of support, according to embodiments of the present invention. 
       FIG. 10  illustrates a chair with a seat  870 , seat attachment members  832 , a flexible frame member  114  having a first portion  152  attached to the rigid support member  116  and a second portion  150  that is free to flex with respect to the rigid support member  116 , according to embodiments of the present invention. A mesh or mesh fabric  160  at least partially spans the frame  114 , according to embodiments of the present invention. As illustrated in  FIG. 5 , the point  550  at which the flexible frame member  114  contacts the seat attachment member  832  may include various forms of coupling, according to embodiments of the present invention. According to some embodiments of the present invention, the seat attachment member  832  is merely in contact with the flexible frame member  114  at contact area  550  to create increasing curvature in the flexible frame member  114  as the back  116  reclines. According to other embodiments of the present invention, the seat attachment member  832  is pivotably coupled with the flexible frame member  114  at pivot point  550 . According to yet other embodiments of the present invention, the seat attachment member  832  is rigidly coupled with the flexible frame member  114  at coupling point  550 . Alternatively, the seat attachment member  832  may be formed integrally with the seat  870  and/or with the flexible frame member  114 , according to embodiments of the present invention. According to some embodiments of the present invention, the pivot or coupling point or points  850  may be located at any location along flexible frame member  114  which permits the flexible frame member  114  to curve as the back  116  reclines; as such, the location at which the flexible frame member  114  attaches to the seat  104 , the seat attachment member  832 , and/or another chair element need not be only along the sides or bottom perimeter of flexible frame member  114 . 
     According to some embodiments of the present invention, outer frame  114  may be constructed with a thermoplastic elastomer such as, for example, a Dupont Hytrel material. Outer frame  114  may thus provide support to a user&#39;s back while being flexible enough to assume a more curved position while the chair is reclined. The support member  116  may be constructed with aluminum and/or a glass-filled nylon, according to embodiments of the present invention. The mesh installed across the outer frame  114  and against which a user&#39;s back rests may be constructed with Dupont Hytrel and polyester fibers, or other elastomeric materials, according to embodiments of the present invention. The springs  832  may be constructed with an acetal copolymer, such as, for example a Ticona Celcon acetal copolymer, according to embodiments of the present invention. 
     Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.