English to French Tech/Engineering Engineering (general) manufacturing of a security document

contexte

"a representative sample of a two-flip lenticular image is printed on the reverse side of representative substrates with lenses, using a simple design such as a rectangle that spans the entire area of the lenses and which is designed to "switch on" and "switch off" as the manufactured security document such as a banknote is tilted."

"The effect produced by optically variable devices containing multiple sets of interleaved image elements is sometimes known as a "flipping image" effect. If a two-channel flipping image is to be produced, then two sets of interleaved image elements are required. "

"Lenticular lenses can be applied to a substrate by using a roll-to-roll lens embossing process. After this process has been completed, rolls of material including embossed lenses are then cut into rectangular sheets and sent to a banknote printer. Lenticular imagery designed to implement the flipping image effect is then applied to the reverse side of the lenticular lenses by the banknote printer, using a sheet-fed printing process. Finally, the printed sheets at the output of the banknote printer are cut into individual banknotes."

"[0005] The lens-to-print skew introduced during manufacture can introduce a moiré fringe into the flipping image effect. In the case of a two-channel flipping image, under ideal conditions only one of the two images is viewed through the lenticular lens at a first viewing angle, and the other of the two images in viewed through the lenticular lens at another viewing angle. However, if a skew is introduced between the printed images and the lenticular lenses, a moiré pattern or fringe can result. In this case, rather than "hard" flip between the two images as the banknote is rotated, diagonal moiré bands roll across the viewed image revealing one image in the moiré band and the other image outside of the moiré band."