Abstract: Light source having a luminescent layer (3,8) whose light is guided through an optical filter (5,9) comprising at least one cholesteric crystal layer (cholesteric filter).

Abstract: The invention relates to a printing form for a rotary relief-printing method, in which the printing dots transferring the printing ink constitute a half-tone screen and are superimposed by a relief structure constituted by indentations. Such printing forms are used, for example in flexographic printing methods for printing glass plates, for example display screens having a luminescent material coating. In the manufacture of these screens, the printing ink must be applied homogeneously and the ink dots appearing in the printed image must have a uniform border area. According to the invention, the printing form is to this end implemented in such a way that the relief structures are arranged homogeneously relative to the printing dots and, if the printing dots are periodically spread across the printing form, these relief structures are superimposed on the printing dots preferably with the same period.