Plastic snap hinge with a flexible element generating the snap action

Claim 1

A single piece plastic snap hinge closure comprising: a lower part having a circumferential wall and a cap comprising a flat top surface part, said lower part and said cap being connected to each other by at least one film hinge defining a pivoting axis of said closure, said lower part forming a pouring spout opening; a flexible element generating a snap action, said film hinge situated on a line defined by an intersection of an outer surface of the circumferential wall and said flat top surface part of the cap when the closure is in a closed position; said flexible element connected to said lower part by a first flexible element film hinge integral with said outer surface of the circumferential wall and to said cap by a second flexible element film hinge integral with said flat top surface part of said cap; said flexible element comprising a plurality of partial sections forming a shape of an "S", said "S" shaped flexible element having two outermost legs being equal in size to each other and interconnected by a central portion, said legs of said "S" shaped flexible element being one of perpendicular and parallel to said outer surface of said circumferential wall in an open position of said closure and being the other of perpendicular and parallel to said outer surface of said circumferential wall in said closed position of said closure; and said flexible element in the open position of said closure disposed as much outside a shape defined by said circumferential wall and said flat top surface of said cap as it is inside said shape int he closed position of said closure.