PURPOSE: To quicken data transfer rapidly by applying parallel transfer of gradation data to a printer head in comparison with a serial transfer system.
CONSTITUTION: A driver IC10 consists of a shift register 11, data bus D 0 ∼D 5 inputting gradation data, a counter 12 with preset, a D-FF13 latching an output of the MSB of the counter 12, a drive transistor 14 for a head 16 and a timer circuit 15 or the like. When the gradation data is inputted together with a data strobe clock signal, gradation data corresponding to a print density of each dot is preset to the counter 12 with preset. When a print-enable signal is inputted, the counter 12 counts down by using a count clock signal and the head 16 is powered until the count reaches 0 or all 1. Thus, each dot is provided with applying time proportional to the gradation data.