Today in 1969, US Patent 3480175 A was issued, an invention of Nick S. Khoury, assigned to the Continental Can Co., for his “Single Pull Ring Tab.” There’s no Abstract, although in the description it includes this summary:

This subject has to do with easy opening can ends having a tear portion defined by a weakening line and wherein a pull tab is attached to the tear portion to effect the removal thereof. The pull tab overlies the tear portion so as to protect the tear portion against accidental removal. By having the pull tab coextensive with the tear portion, more space is made available for a larger tear portion.

This invention relates in general to new and useful improvements in easy opening containers, and more particularly to a novel easy opening panel construction of the type having a tear portion defined by a peripheral weakening line and a pull tab secured to the tear portion and adjacent a starting end thereof to facilitate both the initial rupture of the container panel and the tearing out of the tear portion.

When a tear portion of an easy opening container is placed in the end panel of a container end, in the past the extent of the tear portion has been restricted by the size of the end panel. This has been because the pull tab has normally provided an extension of the tear strip. In accordance with this invention, it is proposed to have the pull tab disposed coextensive with the tear strip whereby the starting end of the tear strip is not restricted to a position immediately adjacent the center of the end panel as has been customary.

Another feature of this invention is to position the pull tab in overlying relation to the tear portion whereby the pull tab protects the tear portion and prevents accidental rupture of the container panel along the weakening line defining the tear portion.

Still another feature of this invention is to provide adjacent the tear portion upstanding ribs which support the pull tab in an elevated position above the tear portion to further prevent the accidental rupture of the container panel along the weakening line defining the tear portion.