Patent ID: 7775601

Claim:
A rack structure for a chair including; a chair back member comprising a frame including two sides having a front, a back opposite to the front, a top end and a bottom end opposite to the top end; and a mounting support including two sides having top ends, wherein said frame includes a support cushion disposed on the front for supporting a user's waist, wherein the frame includes two first connecting tabs fixed on the back of the top ends of the two sides, wherein the frame includes two second connecting tabs formed on and extending from the two sides; wherein said mounting support is fixed onto a base and extends upwardly therefrom, wherein the mounting support includes two coupling segments arranged on the top ends of the mounting support, wherein the two sides of the mounting support further includes two connecting projections intermediate the two coupling segments and the base, and each coupling segment and each connecting projection is couplingly attached in the mounting support by a resilient member, wherein said two first connecting tabs of said frame are connected with said two coupling segments and said two second connecting tabs are connected to the two connecting projections of said mounting support individually, with the two second connecting tabs located intermediate the support cushion and the two first connecting tabs, wherein the cushion is adjustably disposed on the front of the frame, wherein a continuous arcuate groove is provided on the front of each of the two sides of the frame, and wherein an arcuate protrusion is disposed on the support cushion for being fixed to each of the continuous arcuate grooves of the frame.