JPS6487368A - Thermal head drive method - Google Patents

Abstract

PURPOSE:To eliminate the deterioration in printing quality caused by a tailing phenomenon, by variably controlling the start time and pulse width of a printing pulse on the basis of a printing history pattern using a basic cycle pulse as a reference. CONSTITUTION:A history function is simulated from an approximate expression wherein an ink melting rear end position le and an ink melting length l are shown by the relation with an energy density Q. An optimum value to a time taus is selected, and corresponding values le, l are obtained. In this manner, a value taus meeting a formula le+vtaus=nlp;l=lp [n; the number of dot position, lp; the size of an ideal pixel, and v; thermal head travel speed] and an optimum printing pulse width tauw=Q/W can be obtained. [w: supply power density] The dot position number (n) resulting from the simulation is stored in a RAM 13, and corresponding time taus and pulse width tauw are stored in a ROM 12. After a character pattern in the ROM 12 is read by the RAM 13 and the time taus and pulse width tauw corresponding to the dot number position (n) are read, a CPU 11 outputs a corresponding printing pulse PS to heat heating dots 2-1-2-7. In this manner, a printing quality free from a tailing phenomenon and a dispersion in dots can be obtained.