Method and apparatus for manufacturing signs or the like carrying information which is different for different viewing angles

Claim 1

In a method of manufacturing signs or the like carrying displays which are different for different viewing angles, and of the kind which has the configuration of a plurality of parallel ridges with intermediate valleys, a said display being divided into strip-like portions applied in sequence to one side of said ridges, whereby, upon observation obliquely from said one side they appear substantially as an uninterrupted display, while strip-like portions of another display are applied to the other side of said ridges, the steps of (a) dividing each of two images into parallel strips of predetermined and equal widths; (b) composing a third image by placing said parallel strips from both first-mentioned images side by side in alternating sequence; (c) reproducing said third image on a plastic sheet; (d) placing said plastic sheet, provided with said third image, in a mold formed with parallel ridges and intermediate valleys corresponding to said configuration of the finished product, the distance between successive ridge peaks being twice as large as said predetermined width of said strips; (e) locating said sheet so that each ridge peak in said mold is substantially opposite the boundary line between two strips in said third image; (f) heat deforming said sheet against the surface of said mold, while points lying against the ridge peaks remain undisplaced, the zones between said peaks being deformed so that they are brought into substantive engagement with the valleys between the ridges.