THERMAL PRINTER

PURPOSE:To dispense with readjustment of a head electrification energy at the time of assembly of a printer and replacement of a printer head, to reduce the number of assembling processes and to facilitate the replacement and repair of the printer head, by discriminating a rank of a resistance value of the printer head when a power is ON, and by adding a function of setting the head electrification energy suitable for the rank of the resistance value. CONSTITUTION:When the power of a printer control circuit is turned ON, a microcomputer detects the potential of an A/D conversion port P. By setting a voltage corresponding to a rank of a resistance value of a head beforehand in ROM, accordingly, the microcomputer can discriminate the rank of the resistance value of the head. The rank of the resistance value of the head is discriminated in this way, and thereby a time of electrification of the head can be set so that an electrification energy of the head be a prescribed value. This is executed by determining the number of counts for the period of a signal to be generated by an oscillator for an electrification energy control of the thermal head.