PURPOSE: To obtain gradation excellent in the reproducibility of density without having irregular shapes and sizes of dots by arranging main dots formed by energy which is 0-70% the energy applied to dots having the size corresponding to the size of the center-to-center interval of dots arranged on every other dot and arranging sub-dots formed by 0-30% of energy between them.
CONSTITUTION: Main dots 12 are printed along the lateral direction of one thermal head and, subsequently, the thermal head is shifted by a T/2 pitch in the direction vertical to the width of the head to print sub-dots 13 and further shifted by the T/2 pitch in a sub-scanning line direction to print the main dots 12. This printing is repeated until the printing up to the end of one image is completed. After printing, the thermal head is returned to the original position and the head is shifted by the T/2 pitch in a main scanning direction and, this time, the sub-dots 13 are printed at first. Thereafter, the main dots 12 and the sub-dots 13 are alternately printed while the head is shifted by the T/2 pitch in the sub-scanning direction.
SHINOZAKI MICHIO
MARUKAME TOMOYUKI
FUKAI SHIGERU
