Seat back angle adjustment mechanism

The utility model discloses a chair-backrest angle adjustor which mainly consists of a saddle joint seat, a backrest joint seat, a handle component, a gear ring, an eccentric wheel, a moveable gear and a torsional spring. The gear ring, the eccentric wheel and the moveable gear are arranged in a relative seat chamber between the saddle joint seat and the backrest joint seat; the gear ring is provided with an inner gear and is embedded or welded in the backrest joint seat to form a whole with a backrest left joint seat; the eccentric wheel is arranged on the rotating shaft of the handle component; the moveable gear is sheathed on the eccentric wheel, wherein, the moveable gear is provided with an outer gear meshed with the inner gear of the gear ring; the saddle joint seat is provided with a groove matching with the two sides of the moveable gear; one end of the torsional spring is sheathed on the handle component and passes through the rotating shaft of the saddle joint seat, and the other end is hung on the