Patent ID: 8333299

Claim:
A leak resistant drinking cup comprising: a container having a liquid chamber for receiving and holding a quantity of liquid for drinking, the container having an open top; and a lid assembly adapted for removable attachment to the container for selectively closing the open top, the lid assembly comprising: a liquid discharge member through which liquid in the container exits the cup during drinking; a closure member adapted for placement adjacent the open top of the container when the lid assembly is attached to the container; a flexible diaphragm disposed at least in part between the liquid discharge member and the closure member, the diaphragm being moveable between a sealed position in which the diaphragm blocks the flow of liquid from the container to the liquid discharge member, and an unsealed position in which liquid is permitted to flow from the container to the liquid discharge member, the diaphragm being moveable from the sealed position to the unsealed position by a vacuum applied to the diaphragm by a user sucking on the liquid discharge member, the vacuum causing the diaphragm to flex toward the container and at least in part away from the closure member and thereby move the diaphragm from the sealed position to the unsealed position; and at least one protuberance positioned between an upper surface of the closure member and a lower surface of the diaphragm, the at least one protuberance configured as a stop to control flexing of the diaphragm with respect to the closure member.