| 摘要 |
A master mold suitable for use in the manufacture of retroreflective sheeting is disclosed. The master mold comprises an array of cube corner elements formed by two intersecting groove sets. The cube comer elements comprise a tetragonal base, three tetragonal optical faces that mutually intersect at a point to define a cube corner apex, and two non-optical faces. Also disclosed is a method for making a master mold suitable in the manufacture of retroreflective sheeting is disclosed. A first groove set including a plurality of parallel grooves is formed in the working surface of a suitable substrate. Each groove in the first groove set forms a first optical surface and a second non-optical surface. Adjacent grooves in the first groove set are separated by a distance sufficient to define therebetween a structure defined by a first optical surface on one side, a top surface, and a first non-optical surface opposite the first optical surface. A second groove set including a plurality of parallel grooves is then formed in the substrate. Each groove in the second groove set forms a second optical surface and a second non-optical surface. The second groove intersects the first groove set at an intersection angle such that the first optical surface intersects the second optical surface to define an orthogonal dihedral angle between the two surfaces. Formation of the second groove set yields a plurality of structures, each of which includes two mutually perpendicular optical surfaces, a top surface, and two non-optical surfaces. A third optical surface is formed from the top surface of each structure such that the third optical surface defines an orthogonal dihedral angle between the first optical surface and the second optical surface, thereby forming a cube corner element. |
