TAMPER PROOF GRAPHIC PATTERNS

摘要

A method of producing a graphic pattern and a graphic pattern for imprinting substrates, such as documents, especially paper currency, stamps or the like, with lines in the form of lengthwise extending color mounds or peaks is disclosed. There is provided a line grid or pattern which is substantially uniform at least in given field sections and comprises relatively closely juxtaposed non-intersecting and non-contacting lines. The ratio between the height and the spacing of the color mounds forming the lines is selected such that when viewing the pattern below a predetermined boundary inclination angle the base of the valleys between the color mounds or peaks is not visible.