Thermal printer, thermal printing method and process for lifting off wrongly typed characters.

摘要

Ribbon (22) in thermal printing has an outer layer which adheres to printed characters at intermediate temperature, lower than the printing temperature. 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 to 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.