Patent ID: 7637682

Claim:
A ring binder for retaining hole-punched pages, comprising: a housing extending in a longitudinal direction; a pair of pivotable hinge plates received in the housing and clamped together by the housing; and at least one pair of half ring members fixed to the pair of hinge plates respectively and moved between a closed position and an open position when the hinge plates are pivoted with respect to each other; wherein each of the half ring members comprises: an anchoring portion fixed to a corresponding one of the hinge plates; a transverse arm portion having an inner end connected to an upper end of the anchoring portion and extending outwardly in a transverse direction therefrom; an oblique arm portion having a lower end connected to an outer end of the transverse arm portion and extending obliquely and upwardly therefrom, the oblique arm portion being inwardly inclined in the closed position and outwardly inclined in the open position; a curved portion having a lower end connected to an upper end of the oblique arm portion and extending therefrom upwardly and inwardly to form an arc section, wherein, in the closed position, upper ends of the curved portions of the pair of half ring members abut against each other in a face to face manner, and the opposite curved portions form an upwardly directed arc, and wherein the transverse arm portion comprises an inner transverse arm section and an outer transverse arm section, the inner transverse arm section is straight and extends outwardly from the anchoring portion, and the outer transverse arm section is contiguous to an outer end of the inner transverse arm section and is inclined outwardly and downwardly with respect to the inner transverse arm section.