Chair back

Abstract

An office chair ( 10 ) is provided-having a contoured back assembly ( 24 ) comprising a back frame ( 23 ) and a suspension fabric ( 26 ). The fabric is attached to the back frame through a spline ( 58 ) wherein the back frame has a three-dimensional contoured shape formed by overlapped frame rings with the fabric being joined thereto by a spline. The back frame has a split upright section to increase the ability of the left and right halves of the frame to articulate relative to each other. Further, a bayonet connection is provided between the back frame and a support upright which bayonet connection holds together the upper ends of two separate uprights of a tilt control mechanism.

1 . A chair comprising:
 a seat assembly; and   a back assembly supported rearwardly adjacent to said seat assembly, said back assembly comprising a peripheral back frame which projects upwardly above said seat assembly and defines an open area; and   said back assembly further including a suspension fabric which overlies said open area and has a periphery connected to a corresponding periphery of said back frame, said back frame comprising front and rear frame sections which fit one over the other in facing relation and are fixed together wherein said peripheral edge of said back frame comprises a peripheral spline channel extending about the interface between said front and rear frame sections, said spline channel opening outwardly and adapted to receive said peripheral edge of said suspension fabric therein, said back frame further including an elongate spline which engages said periphery of said suspension fabric and is press-fitted into said spline channel in non-removable engagement therewith, said front and rear frame sections defining respective front and rear channel walls of said spline channel wherein said spline maintains said suspension fabric in a taut condition.   
   
   
       2 . The chair according to  claim 1 , wherein said front and rear frame sections include opposing interior faces which define said front and rear channel walls. 
   
   
       3 . The chair according to  claim 1 , wherein said front and rear frame sections are contoured molded frames having a contour such that said opposing interior faces of said front and rear frame sections of a three-dimensional shape such that each of said interior faces is curved. 
   
   
       4 . The chair according to  claim 3 , wherein said spline is longitudinally elongate and has a uniform cross-sectional shape. 
   
   
       5 . The chair according to  claim 3 , wherein said spline is fastened to said peripheral edge of said suspension fabric by fastening means and has a generally flat cross-sectional shape laying flat against an opposing face of said fabric. 
   
   
       6 . The chair according to  claim 5 , wherein said spline is formed of a pair of U-shaped spline sections which each have an initial U-shape and are provided with corner reliefs so that said spline sections are folded over into an inverted U-shape and said inverted spline sections are press-fitted into said spline channel. 
   
   
       7 . A chair comprising:
 a seat assembly; and   a back assembly supported rearwardly adjacent to said seat assembly, said back assembly comprising a peripheral back frame which projects upwardly above said seat assembly and defines an open area;   said back assembly further including a suspension fabric which overlies said open area and has a periphery connected to a corresponding periphery of said back frame, said back frame comprising front and rear frame sections which fit one over the other in facing relation and are fixed together wherein said peripheral edge of said back frame comprises a peripheral spline channel extending about the outer periphery of the interface between said front and rear frame sections, said spline channel opening outwardly and adapted to receive said peripheral edge of said suspension fabric therein, said back frame further including an elongate spline which is contained within an edge portion of said periphery of said suspension fabric and is press-fitted into said spline channel in non-removable engagement therewith, said front and rear frame halves defining respective front and rear wall sections of said spline channel wherein said spline maintains said suspension fabric in a taut condition;   said front and rear frame sections being individually molded frames having a three-dimensional contour which defines opposing interior faces that abut against each other when said front and rear frame sections are joined together, said interior frame faces also having a three-dimensional contour such that each of said interior faces is curved.   
   
   
       8 . The chair according to  claim 7 , wherein said interior faces abut in continuous contact with each other about the periphery of said back frame. 
   
   
       9 . The chair according to  claim 8 , wherein said fabric is affixed continuously about the periphery thereof to the corresponding periphery of said back frame. 
   
   
       10 . The chair according to  claim 9 , wherein said suspension fabric is stretched to a taut condition when said periphery of said fabric is joined to said spline channel. 
   
   
       11 . A chair comprising:
 a seat assembly comprising a seat frame;   a back assembly supported on said seat frame so as to project upwardly therefrom, said back assembly comprising a back frame which joins to said seat frame and has an annular frame shape which defines an open region that is covered by a back fabric which overlies this open region, said peripheral frame being supported on said seat frame by a column structure comprising an upright support column having a lower end joined to said seat frame by a base connector such that said support column is supported in cantilevered relation with respect to said seat frame, an upper end portion of said support column including transverse column arms which extend sidewardly from said support column and have outer sideward ends which are joined to said peripheral frame intermediate the upper and lower edges of said peripheral frame, said support column having separated left and right column halves which each support a respective one of said transverse arms thereon such that said column halves and said arms are movable separate from each other at the upper end portion of said support column while said column halves are joined together at the bottom end of said support column proximate to said base connector, said column halves permitting separate movement of said back frame on the left and right sides thereof.   
   
   
       12 . The chair according to  claim 11 , wherein said left and right column halves are separated from each other by a vertical slot extending along a major length of said support column. 
   
   
       13 . The chair according to  claim 12 , wherein said column halves are supported in cantilevered relation by the bottom end of said support column. 
   
   
       14 . The chair according to  claim 11 , wherein said transverse arms are joined to said peripheral frame approximately midway between said upper and lower frame edges of said frame. 
   
   
       15 . The chair according to  claim 14 , wherein a connector web extends between the bottom edge of said back frame and said support column to restrain movement of the bottom edge of said frame relative to the movement of said upper edge of said frame. 
   
   
       16 . A chair comprising:
 a seat assembly comprising a seat frame;   a back assembly supported on said seat frame so as to project upwardly therefrom, said back assembly comprising a back frame that is joined to said seat frame by a base connector and has an annular frame shape which defines an open region which is covered by a back fabric overlying the open region, said back fabric being joined to said seat frame about the respective peripheries thereof so as to support a back of a chair occupant, wherein said base connector is a bayonet connector which projects downwardly and has a tapered shape which tapers inwardly in the downward direction; and   said seat frame comprising an upright having a front end joined to said seat frame and a rearward end which extends rearwardly and joins to said bayonet connector of said back frame, said upright comprising separate frame sections on opposite sides of said chair which have respective front ends joined to said seat frame and respective rearward ends which converge towards each other and abut against each other to define a connector hub, said connector hub comprising an upward opening socket in which said bayonet connector is slidably received and fixedly joined thereto.   
   
   
       17 . The chair according to  claim 16 , wherein said socket is defined partially by each of said rearward ends of said frame sections. 
   
   
       18 . The chair according to  claim 16 , wherein said hub has a left hub half and a right hub half which are defined respectively by said rearward ends of said frame sections. 
   
   
       19 . The chair according to  claim 18 , wherein said hub halves terminate at opposing inside hub faces and have rib sections projecting inwardly into said socket at said opposing hub faces, said bayonet connection including corresponding slotted portions which extend vertically and receive said rib sections of said hub therein to draw said hub halves sidewardly together and rigidly join said frame sections together at said rearward ends thereof. 
   
   
       20 . The chair according to  claim 18 , wherein said cooperating slots and ribs are tapered such that downward insertion of said bayonet connector draws said hub halves sidewardly together in close, abutting relation. 
   
   
       21 . The chair according to  claim 20 , wherein a fastener is provided which projects upwardly through said hub into fixed engagement with said bayonet connector to displace said bayonet connector downwardly into said socket which draws said bayonet connector and said hub vertically together and draws said rearward ends of said frame sections sidewardly together. 
   
   
       22 . The chair according to  claim 16 , wherein a fastener is provided which projects upwardly through said hub into fixed engagement with said bayonet connector to displace said bayonet connector downwardly into said socket which draws said bayonet connector and said hub vertically together and draws said rearward ends of said upright sections sidewardly together. 
   
   
       23 . A chair comprising:
 a seat assembly comprising a seat frame; and   a back assembly supported on said seat frame so as to project upwardly therefrom, said back assembly comprising a back frame which joins to said seat frame and has an annular frame shape which defines an open region that is covered by a back suspension fabric which overlies this open region, said back fabric being joined to said seat frame about the respective peripheries thereof so as to support a back of a chair occupant, said back assembly further including a cushion which is mountable on said back frame, said cushion including a cushioned pad and pockets formed at upper and lower edges thereof wherein said upper and lower pockets fit over respective upper and lower edges of said back frame to join said cushion to said back frame, said cushion pad overlying said suspension fabric wherein said suspension. fabric supports loads applied to said back frame by an occupant body and said cushion pad overlies said suspension fabric to improve the comfort of a chair occupant.