Patent ID: 6083607
Filing Date: 2000-07-04
Classification: E01F,G02B,G09F,Y10T

Abstract:
A triangular-pyramidal cube-corner retroreflective sheet characterized in that triangular-pyramidal cube-corner retroreflective elements protruded on one common base plane (X-X') are arranged on said base plane (X-X') in a close-packed state so as to face each other by sharing one common base edge on said base plane (X-X') with each other, the base plane (X-X') is one common plane including a plurality of base edges (x, x, . . . ) shared by said triangular-pyramidal retroreflective elements, two these triangular-pyramidal retroreflective elements facing each other form an element pair of substantially same shapes facing each other so as to be respectively substantially symmetric to planes (Y-Y', Y-Y', . . . ) vertical to said base plane (X-X') including said common base edges (x, x, . . . ) on said base plane (X-X'), said triangular-pyramidal retroreflective elements are formed with substantially same pentagonal lateral faces (c.sub.1, c.sub.2) using said common base edges (x, x, . . . ) as one side and substantially same quadrangular lateral faces (a.sub.1, b.sub.1 ; a.sub.2, b.sub.2) substantially perpendicularly intersecting said face c.sub.1 or c.sub.2 using two upper sides of said face c.sub.1 or c.sub.2 using apexes (H.sub.1, H.sub.2) of said triangular-pyramidal retroreflective elements as starting points as one side respectively, sharing one of ridge lines of said triangular-pyramidal retroreflective elements and using said ridge line as one side and the height (h') from the apexes (H.sub.1, H.sub.2) of said triangular-pyramidal retroreflective elements up to said base plane (X-X') including the base edges (x, x, . . . ) of the pentagonal lateral faces (c.sub.1, c.sub.2) of said triangular-pyramidal retroreflective elements is substantially larger than the height (h) from the apexes (H.sub.1, H.sub.2) of said triangular-pyramidal retroreflective elements up to a substantially horizontal plane (virtual plane Z-Z') including base edges (z, w) of other lateral faces (a.sub.1, b.sub.1 ; a.sub.2, b.sub.2) of said triangular-pyramidal retroreflective elements.