US Patent 7758271 Ring mechanism biased to closed and locked position

A ring binder mechanism that retains loose-leaf pages and has ring members that readily lock together in a closed position, preventing accidental opening of the ring members and loss of pages. The mechanism comprises a housing that supports two hinge plates for pivoting motion that brings the ring members to either an open position or the closed position. The mechanism further comprises a control structure supported by the housing for causing the pivoting motion of the hinge plates. A spring plate is engage able with the control structure for urging the control structure to move toward a position blocking pivoting motion of the hinge plates when the ring members move to the closed position.