| 摘要 |
FIELD: printing.SUBSTANCE: protection element comprises a matrix of relief lines, and each line has at least one lateral side of each of which determines the angle of inclination relative to the direction of normal to the matrix. The angle of inclination of the lateral side of at least one matrix line changes gradually along this line so as to form in the light reflection the optical effect of halftones, variable in a function of the viewing angle of the protection element.EFFECT: proposed protection element enables to create complex patterns and identify them at any viewing angle.29 cl, 16 dwg |
