| 摘要 |
PURPOSE:To obtain a drive circuit for thermal head, which is capable of giving stable printing quality even when a number of heating elements to be concurrently energized is varied, by using a system in which heat energy to be applied to each heating element is regulated individually. CONSTITUTION:Printing data 25 selected from a line buffer 22 by a selector 24 are put in an arithmetical unit 26 for calculation of heat storage condition, and the output 27 of the unit 26 is supplied to a pulse width arithmetic unit 28. In the unit 28, using three kinds of data including output signal 31 from a pulse width memory 29 in which each pulse width before one line is stored and black dot signal 33 from a counter 32, pulse width in the line to be recorded at present is determined. The black dot signal 33 represents the ratio of the numbers of black dots in the line to be printed at present in one line. The pulse width signal 34 which is separately determined for every heating element is supplied to the pulse voltage application circuit.
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