Sunlit graphical display arrangement - has panel contg. parallel ridges oriented to form isosceles triangle to produce two-dimensional shadow

摘要

The assembly displays a message, e.g. on the side of a building, in dependence on the incident sunlight and consists of an element having a series of parallel ridges formed on one surface. The series extends at different angles to one another. The ridges preferably have a isocelese triangle cross-section with a 30 degree base angle. Then the incident light has a wavelength interior to the ridge dimension and is incident at different angles to the two series to produce different dimension shadows, the differences produce the image which disappears in dull light. The ridges are of the same height, differing only in their orientation.