Patent ID: 7293832

Claim:
A chair adjustable device comprising: a base; a seat frame pivotably connected to two sidewalls of the base and having a positioning member connected to a rear end thereof; a backrest frame pivotably connected to a rear end of the base; a positioning mechanism connected to the base and an operation handle movably extending through one of the two sidewalls of the base, a distal end of the operation handle movably engaged with a fixed member, a transmission frame connected to a side of the operation handle in the base and movable with the operation handle, a positioning plate movably connected to the transmission frame and biased by a spring so as to be engaged with the positioning member on the seat frame and control the inclination of the seat frame, and a connection member located at an underside of the backrest frame and including two lugs which are respectively pivotably connected to the backrest frame and the positioning member of the seat frame; wherein the transmission frame includes a slot defined through a bottom thereof and a first pair of stops and a second pair of stops extend from two facing insides of the slot at a distance, an extension extends downward from a front end of the positioning plate and a rod extends from an underside of the positioning plate, the extension is movably received in the slot and the spring is received in the slot, two ends of the spring are stopped by the first pair of stops and the second pair of stops.