Patent ID: 7275886

Claim:
A ring binder mechanism for retaining loose-leaf pages, the mechanism comprising: a housing having longitudinal ends; hinge plates supported by the housing for pivoting motion about a pivot axis relative to the housing; rings for holding loose-leaf pages, each ring including a first ring member mounted on a first hinge plate and moveable with the pivoting motion of the first hinge plate, each ring further including a second ring member, the first ring member being movable relative to the second ring member so that in a closed position the two ring members form a substantially continuous, closed loop for allowing loose-leaf pages retained by the rings to be moved along the rings from one ring member to the other, and in an open position the two ring members form a discontinuous, open loop for adding or removing loose-leaf pages from the rings; and a control structure supported by the housing and movable relative to the housing for controlling the pivoting motion of the hinge plates, the control structure producing the pivoting motion of the hinge plates that brings the ring members to said closed position; wherein at least one of the hinge plates includes a protrusion, the protrusion being engageable with the control structure for releasably holding the control structure in a locking position where the control structure blocks the pivoting motion of the hinge plates that brings the ring members to said open position.