Patent ID: 7159943

Claim:
An office chair apparatus comprising: a seat; an adjustable backrest having a support frame; a swivelable movable base: a height-adjustable column extending upwardly from said base, said column supporting said seat and said backrest thereon; a headrest adjustably supported by said backrest, said backrest having an adjustable lumbar support thereon; a central support body anchored to a top of said column along a vertical axis thereof, said seat being frontally connected to a corresponding anterior side of said central support body; a pair of armrest stanchions having respective lower ends hingedly connected to a posterior side of said central support body, said pair of armrest stanchions being hingedly connected in a position intermediate said support frame of said backrest, said support frame of said backrest being hingedly connected at opposite sides thereof to a posterior portion of said seat; a compressed spring interposed between said central support body and said support frame of said backrest so as to allow an oscillating movement between said backrest and said seat; and a locking means cooperative with said backrest and said seat so as to fix a position of said backrest relative to said seat and for selectively preventing against the oscillating movement therebetween, said central support body comprising: a plate that is cantilevered and extends toward an anterior part of said seat; and a pair of parallel arms having an arched shape, each of said pair of parallel arms defining a hinged brace pivotally connected to said seat.