Patent ID: 7827911
Filing Date: 2010-11-09
Classification: B41F

Abstract:
1. A method for printing on a pharmaceutical tablet, comprising: providing an etched printing plate having a pattern of etchings within an area corresponding to an outline of the tablet and which etchings have ink-retaining volumes that vary in a direction across the etching pattern, the ink-retaining volume of each of a plurality of etchings in a first region of the etching pattern is different than the ink-retaining volume of each of a plurality of etchings in a second region of the etching pattern that is spaced apart from the first region in the direction across the etching pattern, the ink-retaining volume of all of the etchings in the first region being the same and the ink-retaining volume of all of the etchings in the second region being the same; placing ink into the etchings; transferring ink from the etchings in the etched printing plate onto an outer surface of a core of the tablet with a larger amount of ink being transferred from etchings having a larger ink-retaining volume than from etchings having a smaller ink-retaining volume, the ink causing variable changes in the color of the outer surface of the tablet in the direction across the etching pattern dependent on the amount of ink being transferred from the etchings onto the outer surface of the core of the tablet; coating a core of the tablet with a coating of a first color before ink in the etchings is transferred onto the outer surface of the tablet; and selecting the colors of the coating and the ink to cause at least three colors to be formed on the tablet, a first color being the color of the coating at locations where ink is not transferred to the outer surface of the tablet, a second color being the color of the ink at locations where the volume of ink masks the color of the coating and at least one additional color being a composite color of the color of the ink and the color of the coating at locations where ink is transferred to the outer surface of the tablet but does not mask the color of the coating.