Automatic bookmark

Claim 1

In combination with a book having covers to which leaves are bound at a back binding, a bookmark mounted for insertion between edge portions of the leaves and made from elastically flexible sheet material, comprising a pair of elongated arms bonded to said covers and projecting therefrom with their respective longitudinal axes generally perpendicular to said edge portions of the leaves adjacent to the back binding, and a pair of elongated legs joined to projecting ends of said arms with longitudinal axes extending at an acute angle from the longitudinal axes of said arms, said legs being joined to each other at a tip section spaced from the back binding between the leaves, the elastically flexible material being a single elongated rectangular blank having first and second opposite sides, a central fold transverse to the longitudinal axes of the arms and concave with respect to said first side to form the tip section, and a pair of dihedral angle folds longitudinally spaced from said central fold at each of the junctions of the arms and legs, each of the dihedral angles of said dihedral angle folds being convex with respect to said first side, said dihedral angle folds including first dihedral angle fold lines between each arm and leg each at an acute angle greater than 45* with the longitudinal axis of each arm, said junctions further including second dihedral angle fold lines adjacent to said first dihedral angle fold lines and at greater angles to the longitudinal axis of each arm than the first angle fold lines, the first and second dihedral angle fold lines intersecting each other at the back edge of the corresponding arm to define a generally triangular area between each arm and leg to accommodate flexing and lateral spacinG between the arms and legs.