Patent ID: 7360839

Claim:
An apparatus for adjusting an armrest of an office chair, comprising: a) a supporting body extending in a longitudinal direction with a bottom end attached to one side of a seat body of the office chair, a receiving cavity being defined by a front side of an upper portion of the supporting body, a plurality of notches being continuously arranged and vertically formed in a front wall of the supporting body; b) a hollow socket mounted on the supporting body and liftable thereon, a flange being formed at a rim of an upward directed opening of the hollow socket, a through hole being directed forward and formed at a bottom of the flange; c) a locking shank having a pivot pin disposed at a top thereof and pivotally received in the hollow socket at a location corresponding to the receiving cavity of the supporting body as well as a protrusion at a bottom thereof for fitting into one of the notches, a spring being interposed between a front side of the locking shank and a wall of the hollow socket for providing the locking shank with an elastic pushing force directed toward the notches, a holding portion passing through the through hole of the hollow socket from the pivot pin of the locking shank; d) a retaining plate locked on the flange of the hollow socket, a positioning portion being positioned at a center of the retaining plate; and e) an armrest body transversely disposed at a top of the hollow socket and movably connected to the hollow socket, the armrest body including: a housing having a cavity formed in a top portion thereof, a bottom plate having a transverse groove at a center thereof for receiving the positioning portion of the retaining plate, two parallel clamping pieces being disposed on the bottom plate within the housing, a plurality of longitudinal ribs being formed on opposite sides of an inner wall of the clamping pieces; a base being interposed between the two clamping pieces of the housing, a groove and a through hole being formed at a top of the base, a plurality of transverse ribs being provided on a top surface of the groove, an arched projection being positioned at both external sides of the base at a location corresponding to the longitudinal ribs of the two clamping pieces; a compression piece positioned within the groove of the base, a connection port being formed at a center of the compression piece and passing through the through hole of the base for mounting on the positioning portion of the retaining plate, the compression piece further includes a screw for positioning, an engaging element being respectively received in a notch at a bottom of front and rear ends of the compression piece; an upper cover retained at a top of the housing; and a top portion being positioned on a surface of the upper cover.