English to French Law/Patents Engineering (general) secuirty documents

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.

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.

By constraining the two-flip design image to fit within this areas, clean two-flip switching image effects are consistently realized across the sheet or in other words in every banknote location.