Ring binder mechanism

A ring mechanism for holding loose-leaf pages, the ring mechanism comprising:

• a housing;
• at least one ring for holding the loose-leaf pages, said ring comprising a first ring member and a second ring member, said ring members being configurable between a closed position and an open position, in the closed position the ring members forming a substantially continuous closed loop for allowing loose-leaf pages retained by said ring to be moved along said ring from one ring member to the other, and in the open position the two ring members form a discontinuous, open loop for adding or removing loose-leaf pages from said ring;
• a hinge mechanism operatively connected to the ring members for configuring said ring members between their open and closed positions, said hinge mechanism comprising a pair of elongate hinge plates supported within the housing for pivoting movement relative to the housing between a first hinge plate position corresponding to the closed position of the ring members and a second hinge plate position corresponding to the open position of the ring members, each of said hinge plates having a free end and being configured to have a first width, a second width narrower than the first width and nearer to the free end of the hinge plate than said first width, and a third width greater than said second width and nearer to the free end of the hinge plate than said second width to facilitate bending of the hinge plate generally at said second width;
• and
• an actuator moveable between a first position corresponding to the closed position of the ring members and a second position corresponding to the open position of the ring members, the actuator comprising an opening arm and a bearing surface on the opening arm engageable with the hinge plates proximate the free ends thereof upon movement of the actuator from its first position toward its second position such that the hinge plates bend proximate their free ends generally at said second width to delay pivoting movement of the hinge plates upon initial movement of the actuator from its first position toward its second position;
• the second width being spaced longitudinally inward from the bearing surface of the opening arm of the actuator when the bearing surface engages the hinge plates to open the ring.