OPTICAL MARKING DEVICE Russian patent published in 2023 - IPC B42D25/36 B42D25/30 B42D25/45 C09K11/06 

FIELD: information protection.

SUBSTANCE: group of inventions relates to an optical marking device, as well as to a protected document and a label, which contain such an optical marking device. In this case, the optical marking device contains one first layer (2) and second layer (3) at least partially located opposite to each other, while at least one of the specified first and second layers contains optically changeable element (4, 5) showing change in color from the first color to the second color. Moreover, the specified first and second colors contrast with color of another layer in such a way that, when optically changeable element (4, 5) shows the specified first color, first layer (2) is visible, and when optically changeable element (4, 5) shows the specified second color, second layer (3) is visible, or, when optically changeable element (4, 5) shows the specified first color, second layer (3) is visible, and when optically changeable element (4, 5) shows the specified second color, first layer (2) is visible. At the same time, optically changeable element (4, 5) contains one or more fluorescent compounds of 4,4-difluor-4-boro-3a,4a-diaza-s-indacene grade and/or grade of β-diketonates of boron difluoride (BF2bdk).

EFFECT: obtainment of an optical marking device.

18 cl, 15 dwg, 2 tbl