A coloring method using a laser system has been proposed in our laboratory. This method has the features as follows. i) The processing objects are plastic materials such as acrylic, nylon, epoxy, polyester etc. ii) Heating the dye solution by the irradiation of a laser, a material can be dyed at a local area of laser irradiation. iii) The images which printed by this method have persistence for erasing such as washing or rubbing. iv) Since the absorptivity of CO2 laser to the dye solution is high, a slap, RF excited CO2 laser was used as a heating source. This method, however, could be expressed only one-color image. In order to perform expression based on the digital image, not one-color but the colors printing of the image has been required.
In this study, the innovative laser coloring method has been introduced for the colors printing. This method combines the laser processing dots which are possessed different colors. For example, by combining the dots of two colors, another color printing can be created. Otherwise, by changing the combining rate of the dots of two colors, more other color printing has been possible. A color printing on plastics using the innovative laser coloring method has been successfully attempted.