Patent ID: 7273249

Claim:
A foldable chair comprising: a seat supporting frame; a first pivot-pin unit defining a first axis; a first link-plate unit pivoted to said seat supporting frame through said first pivot-pin unit; a pivot joint unit defining a joint axis parallel to said first axis; a backrest pivoted to said first link-plate unit through said pivot joint unit; an armrest unit pivoted to said backrest; a front leg unit pivoted to said seat supporting frame and said armrest unit; a second link-plate unit pivoted to said pivot joint unit; a second pivot-pin unit defining a second axis parallel to said first axis and said joint axis; a rear leg unit pivoted to said armrest unit and further pivoted to said second link-plate unit through said second pivot-pin unit; a third pivot-pin unit defining a third axis parallel to said first and second axes and said joint axis; and a lock-plate unit pivoted to said rear leg unit through said third pivot-pin unit so as to be rotatable relative to said rear leg unit between a locked position, in which said lock-plate unit crisscrosses and engages releasably said pivot joint unit, and an unlocked position, in which said lock-plate unit is disengaged from said pivot joint unit.