| 摘要 |
PURPOSE:To improve the printing quality of a thermal printer by controlling the drive time of a heating element of a thermal head with the output of a heat sensitive element responsive to the temperature of the head, thereby suppressing the variation in the printing density. CONSTITUTION:A control circuit 1 controls X, Y drive circuits 2, 3 in response to input information, a plurality of heating elements are arranged in a row, and heating elements of a thermal head 4 connected in a matrix shape are heated. When the temperature of the thermal head 4 is raised, the output of a heat sensitive element becomes large, thereby allowing the output pulse width of a pulse width control circuit 6 to become narrow. Accordingly the drive output width of the Y drive circuit 3 becomes narrow, the pulse width of the pulse current supplied to the heating element becomes narrow and average electric power becomes small, with the result that the temperature rise of the thermal head 4 can be suppressed. |
