Patent ID: 6369947
Filing Date: 2002-04-09
Classification: G06K,Y10S

Abstract:
A surface pattern with a reflection layer embedded between two lacquer layers of a laminate with diffractive structures for creating optically variable effects, and at least one surface portion extending in a plane of the laminate defined by the co-ordinates x and y, the surface portion having a microscopically fine relief structure with a constant number of lines per millimeter, which diffracts visible light at least into first diffracting orders, wherein an optical profile height h of the relief structure is location-dependent modulated by an at least portion-wise continuous, non-rectangular modulation function F(x,y) within at least one of the surface portions so that the relief structure has the geometrical profile shape A(x,y)=g(x,y)*F(x,y), wherein the profile shape g(x,y) describes a diffractive grating having the constant number of lines per millimeter, a constant profile height h and straight or curved parallel furrows, wherein the modulation function F(x,y) changes in its continuous region slowly compared to the profile shape g(x,y), and wherein for visible wavelengths at least a local maximum of an intensity curve of one of the non-zero diffracting orders falls within the range of the optical profile height h values of the relief structure.