Spill proof container cap

Abstract

A spill resistant cap includes a normally closed membrane. The membrane normally restricts a flow through the cap. The membrane includes a cut or slice through the membrane. The cut or slice is preferably and “X”. When pressure is applied to a volume below the membrane and when vacuum is applied to a volume above the membrane, the “X” opens outward, and a flow is allowed to pass through the resulting opening.

1 . A spill resistant container cap comprising:
 a passage;   a normally closed membrane blocking the passage; and   a slit through the membrane to allow the membrane to open when pressure is applied to a volume below the membrane and when vacuum is applied to a volume above the membrane.   
   
   
       2 . The cap of  claim 1 , wherein the slit is two-dimensional when viewed from above the membrane. 
   
   
       3 . The cap of  claim 1 , wherein the slit is an “X”. 
   
   
       4 . The cap of  claim 1 , wherein the slit results in at least one flap in the membrane opening when pressure is applied to a volume below the membrane and when vacuum is applied to a volume above the membrane.