| CPC A47C 7/441 (2013.01) [A47C 7/446 (2013.01)] | 6 Claims |

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1. A chair with an adjustable back depth, comprising a chassis, a seat plate, a back plate, a hinge seat, a pneumatic rod, a trigger piece, a drive piece, a support seat frame, and rocking bars, wherein
the chassis comprises an accommodating cavity and two support plates arranged at a rear end;
the hinge seat comprises a hinge cavity and a rod channel communicated with the hinge cavity;
the support seat frame comprises a bottom hinge cavity and two frame poles, and the two frame poles are hollow, have a front opening, and are communicated with the bottom hinge cavity;
the rocking bars are arranged between an upper hinge plate and a lower hinge plate; a connecting seat is arranged on a rear surface of a back plate; the connecting seat has two hinge grooves with rear openings and lower openings;
the seat plate is fixed to the chassis; the hinge seat is arranged in the accommodating cavity; inner sides of lower ends of the two frame poles are hinged to a rear hinge hole of the two support plates; the lower hinge plate is hinged to a front hinge hole of the two support plates; the rocking bars are embedded into the two frame poles; outer sides of upper ends of the two frame poles are hinged to a rear end of one of the two hinge grooves; the upper hinge plate is hinged to a front end of one of the two hinge grooves; a main body of the pneumatic rod is hinged to the bottom hinge cavity; a piston rod is hinged to the hinge cavity; the trigger piece is hinged to the hinge seat and cooperates with an execution push rod of the pneumatic rod; and the drive piece is arranged on the chassis and cooperates with the trigger piece.
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