Patent ID: 7000792

Claim:
A self-opening cap comprising: a vessel body; a cap; a hinge for coupling said vessel body to said cap; an elastic member with the base section fixed to said vessel body on an inward side of said hinge, said elastic member having a tip section extending to a corner section inside said cap, said vessel body having a stopper block formed in said vessel body on an inward of said elastic member, and said elastic member being deformed with said stopper block to a S-shaped form when said cap is closed, said cap having a notch section formed in said caps at a side opposed to said hinge, two engagement pieces being formed with a clearance therebetween inside said notched section and said cap having a circular cap-side rib formed at a position inwardly from said engagement pieces with a small clearance therefrom, said vessel body having a vessel-side rib formed around a portion of said vessel body, two protruding engagement pieces are formed each extending outward from said vessel-side rib with hooks provided facing against said protruding engagement pieces respectively and formed at positions outwardly from said protruding engagement pieces and a push piece providing said hooks with hook-side portions, said push piece disposed for oscillating in the vertical direction around a supporting position for releasing the locked state.