| 摘要 |
PURPOSE:To greatly widen the temperature range in which intermediate gradations can be reproduced, by switching a table and the voltage of a head power source by an input-output characteristic converting means and a voltage-regulating means according to gradation data and an output from an A/D converting means. CONSTITUTION:Gradation level data inputted are read through a first port 6, and are stored. A digital value obtained by detecting the temperature in the vicinity of a thermal head by a temperature-detecting means 13 and digitizing the resultant temperature signal by an A/D converting means 14 is read through a second port 7, and is stored. An address in a voltage setting table (f) developed in a second RAM 5 is given according to the temperature level detected, thereby obtaining voltage data A for a head power source 15. The data A is outputted to a D/A converting means 16 through a fourth port 9, the voltage of the head power source is varied, and the varied voltage is applied to a thermal head 12. An address in a two-dimensional gammacorrection table f' developed in a second RAM 5 is given according to a gradation level and the temperature level, thereby obtaining pulse width data B, which is outputted to a pulse-generating means 10 through a third port 8. With this arrangement, it is possible to greatly widen the temperature range in which temperature correction can be achieved. |
