Abstract: A thermal printer is provided in which unevenness of printing due to temperature changes of a power source, can be prevented from occurring as well as prevented useless power consumption with a simple configuration. The temperature of a cell is measured with a cell temperature measuring section, and by referring to a table showing a relationship between the temperature and the internal resistance of the cell, which is stored in ROM, corresponding resistance is acquired. An energizing pulse width for energizing each heater element of a thermal head is calculated while the above-mentioned resistance is taking into consideration, to thereby energize and drive the above each heater element.

Abstract: Dynamic division drive of a thermal printer is simplified to reduce the number of signal lines, and history control drive is made efficient to shorten time necessary for data transfer. The thermal size printer comprises a plurality of heating arrays for printing split up into blocks and arranged in a line, a plurality of driver units for driving a block of the heating arrays separately from other blocks, and a logic circuit for controlling the driver units. The logic circuit comprises a block specifying means for specifying one driver unit or two or more driver units to be operated according to block selection data BDAT inputted from the external. Only the specified driver units are all at once operated according to a single strobe signal DST inputted from the external. Further, the logic circuit comprises a data operation means for internally originating history data based on print data HDAT inputted from the external.