Triangular-pyramidal cube-corner retroreflective sheeting

A triangular-pyramidal cube-corner retroreflective sheeting characterized in that triangular-pyramidal cube-corner retroreflective elements protruded beyond a first common bottom plane (virtual plane X-X′) are arranged so as to be faced each other in the closest-packed state on the first bottom plane (virtual plane X-X′) by sharing each base edge on the first bottom plane (virtual plane X-X′), the first bottom plane (virtual plane X-X′) is a common plane including the base edges (x, x, . . . ) shared by the triangular-pyramidal reflective elements, two opposite triangular-pyramidal reflective elements form a substantially-same-shape element pair faced each other so as to be substantially symmetric to planes (Y-Y′, Y-Y′, . . . ) vertical to the first bottom plane including the shared base edges (x, x, . . . ) on the first bottom plane (virtual plane X-X′), lateral faces (faces c1 and c2) using each of the shared base edges (x, x, . . . ) of the triangular-pyramidal reflective elements as one side are respectively formed into a substantially same triangle and arranged along the shared base edges (x, x, . . . ), two other lateral faces (faces a1 and b1 or faces a2 or b2) forming the triangular-pyramidal reflective elements form substantially same quadrangular lateral faces by using each of two upper sides of the triangular lateral faces (faces c1 and c2) started from apexes (H1 and H2) of the triangular-pyramidal reflective elements as one side and sharing one ridge line of the triangular-pyramidal reflective elements as one side, a second bottom plane (Z-Z′) including base edges (z and w) of the quadrangular lateral faces (faces a1 and b1) formed because the quadrangular lateral faces (a1 and b1) cross the corresponding quadrangular lateral faces (face a2 or b2) of other triangular-pyramidal reflective elements adjacent to the lateral faces (faces a1 and b1) is substantially parallel with the first bottom plane (virtual plane X-X′) and located substantially below the first bottom plane (X-X′) including the base edges (x, x, . . . ) of the triangular-pyramidal reflective elements, and an optical axis via apexes of the triangular-pyramidal reflective elements tilts by at least 3° from a vertical line (H1-P) extended from apexes of the triangular-pyramidal reflective elements up to the second bottom plane in a direction in which the difference (q−p) between the distance (q) from the intersection (Q) between the optical axis and the second bottom plane (Z-Z′) up to the plane (Y-Y′) including the base edges (x, x, . . . ) shared by the element pair and vertical to the first bottom plane (X-X′) and the distance (p) from the intersection (P) between a vertical line extended from the apexes (H1 and H2) of the elements to the second bottom plane (Z-Z′) and the second bottom plane (Z-Z′) up to the vertical plane (Y-Y′) including the base edges (x, x, . . . ) shared by the element pair becomes negative (−).