US Patent 7134569 Cup lid having frangible straw slot depression

A tear-back drink-through lid for a drinking cup sealingly engages the drinking cup at an annular mounting portion with a downwardly extending annular skirt. The tear-back section extends from the inner skirt to a hinge and has an outwardly extending raised protrusion. When the tear-back section is torn away from the lid and pivoted about the hinge, the raised protrusion is frictionally engaged by the end walls of the recess and retained within the recess. The recess further includes a straw slot formed therein defined by two sloping converging sidewalls extending from the upper surface the lid at different angles to form a frangible juncture at the deepest portion of the recess.