Chair with lumbar support and conforming back

Abstract

A task chair including a seat support structure, a backrest frame attached to the seat support structure, and a backrest supported by the backrest frame. The backrest includes a back support surface which may ergonomically conform to a seated user when the user shifts positions while sitting in the chair. The back support surface includes rigid and flexible portions connected to one another, the flexible portions allowing resilient flexing of the back support surface to create conformance zones which dynamically support the back of a seated user in an ergonomic manner.

1 . A chair, comprising: 
 a seat support structure;    a backrest frame connected to said seat support structure; and    a backrest formed of a flexible portion having a Shore D hardness of at least 5, and at least two rigid portions spaced apart from one another and embedded within said flexible portion, said backrest frame connected to each of said rigid portions at respective flex joints, said backrest resiliently movable about said flex joints to conform to a seated user.    
   
   
       2 . The chair of  claim 1 , wherein said flexible portion is formed of an elastomeric material.  
   
   
       3 . The chair of  claim 1 , wherein said flexible portion has a Shore D hardness between 20 and 80.  
   
   
       4 . The chair of  claim 1 , wherein said flexible portion has a Shore D hardness between 30 and 60.  
   
   
       5 . The chair of  claim 1 , wherein said rigid portions are made from a material selected from the group consisting of wood, metal, and plastic.  
   
   
       6 . The chair of  claim 1 , wherein said rigid portions are respectively disposed along opposite sides of said backrest, said backrest frame having opposite ends respectively connected to said rigid portions at said flex joints.  
   
   
       7 . The chair of  claim 1 , wherein each said rigid portion includes a spring member extending therefrom, each said spring member embedded within said flexible portion.  
   
   
       8 . The chair of  claim 1 , wherein each said flex joint comprises: 
 a bolt connecting said rigid portion of said backrest to said backrest frame, said bolt including a substantially spherical pivot head disposed within a thickness of said rigid portion; and    a resilient bushing disposed between said rigid portion and said backrest frame, said bushing compressible to provide a return force against pivotal movement of said backrest about said pivot head.    
   
   
       9 . The chair of  claim 1 , wherein said backrest includes a flexible upper portion, said upper portion resiliently moveable about said flex joints between a substantially upright position and a reclined position responsive to movement of a seated user.  
   
   
       10 . The chair of  claim 1 , wherein said backrest includes a lumbar support portion projecting outwardly from said backrest in an area of a lumbar region of a back of the seated user, said lumbar support portion resiliently moveable about said flex joints responsive to movement of a seated user.  
   
   
       11 . A chair, comprising: 
 a seat support structure;    a backrest frame connected to said seat support structure; and    a backrest including a flexible body portion having a Shore D hardness of at least 5 and surrounding and extending between at least two rigid portions, said at least two rigid portions pivotally attached to said backrest frame at respective joints which are disposed proximate opposite sides of said backrest.    
   
   
       12 . The chair of  claim 11 , wherein said flexible body portion has a Shore D hardness between 20 and 80.  
   
   
       13 . The chair of  claim 11 , wherein said flexible body portion has a Shore D hardness between 30 and 60.  
   
   
       14 . The chair of  claim 11 , wherein said flexible body portion is formed of an elastomeric material.  
   
   
       15 . The chair of  claim 11 , wherein each said rigid portion is embedded within said flexible portion, and is made from a material selected from the group consisting of metal, plastic, and wood.  
   
   
       16 . The chair of  claim 11 , wherein each said flex joint comprises: 
 a bolt connecting said rigid portion of said backrest to said backrest frame, said bolt including a substantially spherical pivot head disposed within a thickness of said rigid portion; and    a resilient bushing disposed between said rigid portion and said backrest frame, said bushing compressible to provide a return force against pivotal movement of said backrest about said pivot head.    
   
   
       17 . The chair of  claim 11 , wherein each said rigid portion further comprises a spring member extending therefrom, said spring member embedded within said flexible portion.  
   
   
       18 . The chair of  claim 11 , wherein said backrest includes a flexible upper portion, said upper portion moveable about said joints between a substantially upright position and a reclined position responsive to movement of a seated user.  
   
   
       19 . The chair of  claim 11 , wherein said backrest includes a lumbar support portion projecting outwardly from said backrest in an area of a lumbar region of the back of the seated user, said lumbar support portion moveable about said joints responsive to movement of the seated user.  
   
   
       20 . A chair, comprising: 
 a seat support structure;    a backrest frame connected to said seat support structure; and    a backrest including a flexible portion having a Shore D hardness of at least 5, said flexible portion having at least one rigid member embedded therein, said flexible portion and said at least one rigid member together defining a back support surface, said backrest frame connected to said at least one rigid member at at least one flex joint, said backrest resiliently movable about said at least one flex joint to conform to a seated user.    
   
   
       21 . The chair of  claim 20 , wherein said flexible body portion has a Shore D hardness between 20 and 80.  
   
   
       22 . The chair of  claim 20 , wherein said flexible body portion has a Shore D hardness between 30 and 60.  
   
   
       23 . The chair of  claim 20 , wherein said flexible body portion is formed of an elastomeric material.  
   
   
       24 . The chair of  claim 20 , including a pair of said rigid members respectively disposed along opposite sides of said backrest, said backrest frame having opposite ends respectively connected to said rigid members at said flex joints.  
   
   
       25 . The chair of  claim 20 , wherein each said flex joint comprises: 
 a bolt connecting said rigid portion of said backrest to said backrest frame, said bolt including a substantially spherical pivot head disposed within a thickness of said rigid portion; and    a resilient bushing disposed between said rigid portion and said backrest frame, said bushing compressible to provide a return force against pivotal movement of said backrest about said pivot head.    
   
   
       26 . A chair, comprising: 
 a seat support structure;    a backrest frame connected to said seat support structure; and    a backrest including a flexible body portion having a Shore D hardness of at least 5 and surrounding and extending between at least two rigid portions, said at least two rigid portions attached to said backrest frame at respective joints, said body portion including an upper portion flexible between a substantially upright position and a reclined position responsive to movement of a seated user.    
   
   
       27 . The chair of  claim 26 , wherein said flexible body portion is formed of an elastomeric material.  
   
   
       28 . The chair of  claim 26 , wherein said flexible body portion has a Shore D hardness between 20 and 80.  
   
   
       29 . The chair of  claim 26 , wherein said flexible body portion has a Shore D hardness between 30 and 60.  
   
   
       30 . The chair of  claim 26 , wherein each said joint comprises: 
 a bolt connecting said rigid portion of said backrest to said backrest frame, said bolt including a substantially spherical pivot head disposed within a thickness of said rigid portion; and    a resilient bushing disposed between said rigid portion and said backrest frame, said bushing compressible to provide a return force against pivotal movement of said backrest about said pivot head.