A laser labeling technology, "Labelflash
TM (LF)", consists of drawing blue and silver-white monochromatic label images, by using a recording head of a DVD drive, on a dye layer for labeling placed 0.6 mm under the surface of the label side of a disc. This time, we developed two new kinds of value-added LF disc technologies. First one is a mat-type technology. In the case of the present type of LF disc, it is difficult to see a drawn pattern of the label side by interferences of reflective lights from the disc surfaces. We decreased this interferences by scattering the reflective lights with a coarse backside of a label substrate. Second one is a colour-variation type technology. In order to make different colour images, we used mixtures of three primary colour dyes (yellow, magenta, and cyan) and sensitizing dyes for the dye layers. The mixing ratios of these dyes were determined through simulations in which absorption spectra for mixtures of these dyes were calculated as a superposition of the spectra of the individual dyes. We have thus developed new colour-variation-type LF discs that can make monochromatic images in green, sepia and black to succeed in drawing coloured label images.
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