Ergonomic chair

Abstract

An ergonomic chair provides continuous support to the seated user throughout a broad range of postures by pivoting both the seat and back supporting cushions about a first or common axis disposed above the seat support cushion and in front of the back support cushion. The back supporting portion also independently pivots about a second horizontal axis proximate the lumbar region in a manner that allows the back supporting cushion to assume an angle that provides permanent contact with the seated user's back when said user is leaning back against the back support cushion. The springs that otherwise oppose the free rotation about the first and second axis are balanced such that the force inherently exerted by the user during movement through a range of seated postures is sufficient to initiate the coordinated rotation of the seat and back supporting element. No additional exertion is required once the user has reached the desired inclination, as the return springs are selected to counterbalance the redistributed weight of the user. Thus, full contact of the back supporting portion with the user's back is achieved over a full range of postures to provide proper ergonomic support, allowing the user to stay at task. In combination with such motion, which maintains the head at a level and angle such that the eyes can remain focused on their primary visual target without need to adjust the height, depth or angle of the target. The chair can offer armrests that support the forearms of the seated user to reduce the load carried by the arms, shoulders, neck and back and cooperate with the motion of the seat and back supporting elements to maintain ergonomically correct orientation of the hands to the keyboard or work surface.

1 . A chair comprising: 
 a) a frame having a forked armature extending upward there from,    b) a seat support mounted in suspension about a first rotary axis from the forks of said frame,    c) a U-shaped mounting bracket having a left and right terminus, each of which is disposed in rotary connection about the forks of the armature and in substantial coincidence with the first rotary axis,    d) a back support disposed between the left and right terminals of said U-shaped back support, being mounted to pivot thereon about a second rotary axis that is located behind the back support cushion and proximate the lumbar spine region of the seated user.    
     
     
         2 . A chair according to  claim 1  wherein the pivoting movement of said back support cushion about the second rotary axis is opposed by a spring.  
     
     
         3 . A chair according to  claim 1  wherein the pivoting movement of said back support cushion about the second rotary axis is opposed by a tension spring.  
     
     
         4 . A chair comprising: 
 a) a frame having a forked armature extending upward there from,    b) a seat support mounted in suspension about a first rotary axis from the forks of said frame,    c) a U-shaped mounting bracket having a left and right terminus, each of which is disposed in rotary connection about the forks of said armature and in substantial coincidence with the first rotary axis,    d) at least one laterally disposed arm rests connected to the forks of the armature so as to remain in a substantially horizontally disposed position regardless of the tilt of said seat support or said back support cushion, wherein the armrest comprises a horizontally pivoting portion.    
     
     
         5 . A chair according to  claim 4  wherein the horizontally pivoting portion of said at least one laterally disposed arm rest double pivots with free rotation.  
     
     
         6 . A chair according to  claim 4  wherein the horizontally pivoting portion of said at least one laterally disposed arm rest comprises a pivoting auxiliary device pad.  
     
     
         7 . A chair according to  claim 6  wherein the pivoting auxiliary device pad is tear drop shaped.  
     
     
         8 . A chair comprising: 
 a) a seat support mounted above the ground,    b) a back support cushion generally perpendicular to said seat support and connect thereto about a rotary axis that is located behind the back support cushion and proximate the lumbar spine region of the seated user,    c) wherein the pivoting movement of said back support cushion about the second rotary axis is opposed by a tension spring.    
     
     
         9 . A backrest for a chair comprising: 
 a) a back support surface,    b) a rotary mount attached to said back support surface enabling the forward and backward rotation of said support to follow the load applied by a seated user,    c) a spring attached to at least a portion of the rotary mount and biased to urge said back support surface to a starting point and resist a seated user reclining to rotate said back support from said starting point about said rotary mount whereby the energy stored in said spring from the rotation then assists the user in coming back to an upright posture from the reclined posture.    
     
     
         10 . A backrest for a chair according to  claim 9  wherein the vertical height of the rotary mount with respect to a seat supporting the user is adjustable.  
     
     
         11 . A backrest for a chair according to  claim 9  wherein the starting point of said back support surface is angularly adjustable with respect the rotary mount thereof.  
     
     
         12 . A backrest for a chair according to  claim 10  wherein the substantially vertical starting point of said back support surface is angularly adjustable with respect the rotary mount thereof.  
     
     
         13 . A backrest for a chair according to  claim 9  wherein the forward and backward rotation of said support follows the load applied by a seated user when the rotation axis is proximate the seated user's lumbar spine.