| 摘要 |
PURPOSE:To perform both gamma compensation and temperature compensation simultaneously through a simple circuit constitution, by selecting and outputting an ROM table corresponding to a detected temperature, and outputting a pulse signal corresponding to said table to the heat generating element of a thermal head. CONSTITUTION:A temperature detector 14 measures the ambient temperature of the thermal head and its measurement result is inputted to a table selecting circuit 12 through an A/D converter 13. The table selecting circuit 12 outputs ROM tables 111-11n selectively to a comparator 17 corresponding to the ambient temperature level. Therefore, the set value of the number of pulses after the temperature compensation based upon the relation between print density and the ambient temperature is inputted to the comparator 17. The pulse signal from an oscillator 16 is integrated by a counter 15 and when its pulse number coincides with the set value, a gate circuit 18 is closed to perform halftone recording by pulses from the gate circuit 18. |
