Patent ID: 6817724
Filing Date: 2004-11-16
Classification: G02B,Y10T

Abstract:
Triangular-pyramidal cube-corner retroreflective elements characterized in that triangular-pyramidal cube-corner retroreflective elements protruding beyond a common bottom plane (Sx-Sxâ€²) share one base edge (x) on said bottom plane (Sx-Sxâ€²) and are arranged in the closest-packed state so as to be faced each other, said bottom plane (Sx-Sxâ€²) is a common plane including a plurality of the base edges (x,x, . . . ) shared by said triangular-pyramidal reflective elements, two triangular-pyramidal reflective elements faced each other include said shared base edges (x,x, . . . ) on the bottom plane (Sx-Sxâ€²) and form a substantially same-shape element pair faced each other so as to be symmetric to planes (Lxâ€”Lx, Lxâ€”Lx, . . . ) vertical to the bottom plane (Sx-Sxâ€²), and when assuming the height from the bottom plane (Sx-Sxâ€²) including the base edges (x,x, . . . ) shared by the two triangular-pyramidal reflective elements faced each other up to apexes (H1 and H2) of the triangular-pyramidal reflective elements as hx, the height from a bottom plane (Sy-Syâ€²) including other base edges (y,y, . . . ) of the triangular-pyramidal reflective elements up to the apexes (H1 and H2) of the triangular-pyramidal reflective elements as hy, and the height from a bottom plane (Sz-Szâ€²) including still other base edges (z,z, . . . ) of the triangular-pyramidal reflective elements up to the apexes (H1 and H2) of the triangular-pyramidal reflective elements as hz, at least any two of hx, hy, and hz are substantially different from each other and a mirror reflective layer is formed on reflective side faces of the triangular-pyramidal reflective elements.