US Patent 9596941 Chair back with height and lumbar adjustment

An office chair including a chair back assembly that is independently adjustable to adjust the vertical height of the chair back and to provide lumbar support. The chair back assembly includes a flexible back shell that is movable vertically along a back support yoke. The vertical movement of the flexible back shell adjusts the vertical height of the chair back assembly relative to the seat. The chair back assembly further includes a lumbar adjustment mechanism having an adjustment cable connected to a bottom end of the flexible back shell. Operation of the lumbar adjustment mechanism moves the bottom end of the flexible back shell vertically within a pair of spaced lower movement slots. The movement of the bottom end of the flexible back shell increases the amount that the flexible back shell protrudes from the back support yoke, thereby increasing the lumbar support.