Retroreflection sheet and outer type illumination system

摘要

The retroreflective sheet of the present invention comprises a surface layer ( 1 ) including at least one layer, a focusing layer ( 2 ) containing glass spheres ( 3 ), and a metal reflective layer ( 4 ) on the back side of the focusing layer ( 2 ), wherein the glass spheres ( 3 ) are disposed at random locations in the thickness direction of the focusing layer ( 2 ). The external illumination system of the present invention comprises a sign having a sign face including the above-mentioned retroreflective sheet, and an external illumination source, and the distance from the illumination source to the sign face is within a range of at least 1 m and no more than 100 m. The present invention thereby provides a retroreflective sheet and an external illumination system with which wide-angle reflective performance with a wider incidence angle and observation angle can be ensured.