Thermal Printhead Drive Circuit for High Speed Printing
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
A typical thermal printing system uses an electrically heated print element which is energized with current pulses. Since the duty cycle of the current pulse is relatively short, the actual temperature of the print element follows the curve shown in Fig. 1A when high speed printing is attempted. The first several current pulses gradually bring the temperature of the print element into the paper printing temperature range. Typically, the first current pulse does not raise the temperature into the print range. The second and third pulses extend partially into the print range. Not until the fourth or later pulse is the print head at the proper operating temperature. This causes a lack of definition in the printed character.