Thermal printer and heat history control method

A thermal printer that prints on a recording medium in which plural colors can be produced depending upon the heat energy applied to the recording medium, comprising:

• a thermal element that produces the plural colors;
• a thermal element drive circuit that drives the thermal element;
• a receiving circuit that receives color data specifying either no color or one of said plural colors;
• memory that stores the color data received by the receiving circuit;
• and
• a drive control circuit that supplies a particular drive signal to the thermal element drive circuit based on the current color data received by the receiving circuit, and previous color data stored in the memory;
• and
• wherein the drive control circuit comprises:
• a strobe signal generator that generates a strobe signal and defines a plural part strobe period of the drive circuit, the strobe signal comprising one or more of at least three individual pulses having different pulse widths from each other;
• and
• a logic circuit that determines whether or not one of the at least three individual pulses is applied to drive the thermal element during a corresponding one of the plural parts of the strobe period based on at least
• presence or absence of current first color data stored in said memory,
• presence or absence of previous first color data stored in said memory,
• presence or absence of current second color data stored in said memory, and
• presence or absence of previous second color data stored in said memory.