Practical implementation of supplying DOVIDs for banknotes

Although Diffractive Optically Variable Image Devices (DOVIDs) are a relatively recent addition to the armoury available to the currency printer they are already used on more than 80 banknote denominations worldwide. Design and integration of the DOVID into the thematic sense of the whole note are established as critical factors in insuring ease of recognition and integrity of the document. The effects of scatter as a result of roughness at the paper surface are handled in simplistic communication terms. Practical improvements are offered that can improve the legibility of the device on the document. The most popular form of application of the DOVID to a banknote is as a discrete image or contiguous stripe that is carried as a metallised transfer layer on a web of hot-stamping foil. Whilst many security printers are familiar with the application of conventional hot-stamping foil the need to maintaining web stability for the accurate placement of images posses additional challenges. Recommendations are offered, again from a practical perspective, that can improve the overall speed and accuracy of the transfer process.