US Patent 7273249 Foldable chair

A foldable chair includes: a seat supporting frame; a first pivot-pin unit; a first link-plate unit pivoted to the seat supporting frame through the first pivot-pin unit; a pivot joint unit; a backrest pivoted to the first link-plate unit through the pivot joint unit; an armrest unit pivoted to the backrest; a front leg unit pivoted to the seat supporting frame and the armrest unit; a second link-plate unit pivoted to the pivot joint unit; a second pivot-pin unit; a rear leg unit pivoted to the armrest unit and further pivoted to the second link-plate unit through the second pivot-pin unit; a third pivot-pin unit; and a lock-plate unit pivoted to the rear leg unit through the third pivot-pin unit.