Abstract: Ribbon (22) in thermal printing has an outer layer which adheres to printed characters at intermediate temperatures, lower than printing temperatures. The printhead (7) has a column of electrodes (9) which sweep across the character area. Lift-off is accomplished by the pattern control (40) controlling the current source (38) to provide rapid, square wave pulses displaced in phase 180 degrees at adjoining electrodes (9). The high level of the pulses is about that of the level at printing, and the pulses are sufficiently rapid so that their net effect is to raise the outer layer ribbon (22) to the intermediate temperature. At areas corresponding to underlines of characters, duration of the up period is longer. Good, long term reliability is achieved by the significant erase level being very close to the print level.

Abstract: Disclosed is an ink for use in ink jet printers, the ink containing a water soluble dye, and a polyamine containing 7 or more nitrogen atoms per molecule, with the ink composition having a pH of 8 or above, the upper pH limit being dye decomposition dependent. The ink has improved water-fastness over an equivalent ink formulation without the polyamine additive.