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US 4,861,620 AGranted
Method of laser marking
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsKenkoku Azuma, Masaaki Sakaki
Life of this patent
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Abstract
A pigment layer is provided on a surface of an article on which a marking is to be formed and is irradiated with patterned laser light to change internal molecular structure of pigment to thereby change its color. The marking can be multicolored by a suitable selection of pigment and laser energy density.
Claims4
A method of marking an article surface comprising the steps of
- coating the article surface with pigment or mixing the pigment into the material of the article, wherein said pigment is capable of changing its original color to another color at or higher than a predetermined temperature, and
- irradiating portions of the pigment coating with a marking laser light, whereby the irradiated portions are marked by the another color,
- wherein said pigment is a combination of a plurality of different pigments providing different colors at different temperatures, respectively, and said marking laser is a mixture of a corresponding number of laser beams having different energy densities necessary to heat said article surface to said different temperatures, respectively, whereby said irradiated portions of said article surface are marked with said different colors.
Dependencies are inferred from the claim text.