Patent ID: 7360962
Filing Date: 2008-04-22
Classification: B42F

Abstract:
1. A ring binder mechanism for binding the sheets of loose leaves, the mechanism comprising: an elongated spring plate that extends longitudinally and, in profile, has a shallow U-shaped configuration and opposite edges which extend substantially toward each other, said spring plate having at least one hole with a bushing therein for attachment of the ring binder mechanism to a file folder; two parallel elongate hinge plates supported by said spring plate for pivotal toggle motion relative to the spring plate about a central hinge line, the hinge plates being mounted in parallel and retained by the opposite edges of the spring plate; a plurality of rings for clasping said sheets of loose leaves, each of the rings comprising a pair of half ring elements mounted on said hinge plates, with one half ring element of each pair being attached to one of the hinge plates and the other half ring element of the pair attached to the other hinge plate, with the two half ring elements of each pair in substantial alignment, the pairs of half ring elements being movable with said hinge plates to toggle between an open position and a closed position and forming a substantially annular shape when in the closed position; and wherein free ends of the half ring of each pair elements form a nesting configuration when in the closed position, the free end of one half ring element of each pair having a centrally concave nesting portion and the free end of the other half ring element of the pair having a centrally convex nesting portion, said concave portion and said convex portion being symmetrical about an axis line of the respective ring elements of the pair, so that when the pair of half ring elements are in the closed condition, the free ends of the half ring elements are aligned to each other and form a single line contact-engagement so that the convex nesting portion and the concave nesting portion are nested together tightly; wherein said centrally convex portion of one half ring element of each pair has an annular external conical surface which extends directly from a first cylindrical outer surface of a cylindrical rod forming the respective one half ring element to a second cylindrical outer surface of a cylindrical end portion thereof: wherein said centrally concave portion has a centrally cylindrical hole that is formed in the end of the other half ring element of each pair and an internal conical surface extending between a third cylindrical inner surface of said cylindrical hole toward a fourth cylindrical outer surface of a cylindrical rod forming the respective other half ring element; and wherein a maximum diameter of the internal conical hole surface is smaller than that of said cylindrical rod forming the respective other half ring element, a cone angle of said internal conical surface is smaller than that of the annular external conical surface of the centrally protruding outwards nesting portion, such that when the half ring elements are in the closed condition, a connecting portion between the fourth cylindrical outer surface of the concave nesting portion and the internal conical surface thereof engages with the external conical surface of the convex nesting portion in a single line contact such that the end portion of the convex nesting portion extending past the line contact does not engage with the concave nesting portion and thereby causes the convex nesting portion to nest centrally in the concave nesting portion.