Image Number 3 for United States Patent #6394686.
A concealed, clinch ("crown") fastener (30) includes a cylindrical body (32) closed at one end to form a surface (34) deformable to attach the fastener to a binder ring mechanism (18). A first set (40) of prongs (42) extend from the opposite, open end of the fastener body to attach the fastener to a binder spine material (M) when the prongs are driven into the material. A second set (50) of prongs (52) are also formed at this end of the fastener, intermediate adjacent prongs comprising the first set. These prongs are shorter in length than those comprising the first set, and while the prongs forming the first set extend from the body in one direction, the prongs forming the second set extend in the opposite direction. The fastener provides better holding strength than other concealed fasteners and better resists pulling and twisting forces which tend to pull the mechanism away from the binder cover than these other fasteners.