CONTROLLING METHOD OF TEMPERATURE OF THERMAL PRINTER

PURPOSE:To obtain a clear print and to eliminate the nonuniformity in a printing density and tailing, by fixing an impressed power, and by controlling a printing time to be within the upper and lower limits set on the basis of the condition of color development varying with the temperature of a head so that a consumed power be constant. CONSTITUTION:The temperature of a thermal printer is controlled by setting a printing time (t) in the range within prescribed upper and lower limits t1 and t2, t1>t>t2, which is determined on the basis of the condition of color development varying with the temperature of a printing head, so as to make constant a consumed power (p) represented by an equation p=kxt wherein the consumed power of the head is expressed by (p), an impression time by (t) and a printing factor by (x) and (k) denotes a constant, with an impressed voltage fixed. In the control of the thermal printer as described above, the impression time is controlled so that an average consumed power be constant, and thus a recorded image free from tailing, the nonuniformity in a print, etc. can be obtained even when the printing factor varies in a wide range as is the case of a graphic printing.