Patent ID: 7600846

Claim:
An accumulated-heat correction apparatus for a thermal head, wherein print data of each line are outputted to the thermal head, and a conduction time of the thermal head is controlled on the basis of the print data, comprising: cumulative-data calculation means for calculating cumulative data which is ascribable to accumulated heat of the thermal head up to a previous line; next-line data calculation means for calculating print data of a next line; correction-data generation means for calculating correction data which corrects print data of a current line, by using the cumulative data and the next-line data; wherein when a conduction time of the value of the print data of the next line is greater than the maximum of the available conduction time or less than the minimum thereof, the correction-data generation means calculates a correction accumulated-heat magnitude by subtracting an uncorrectable component of the conduction time of the next line from a conduction time of the current line; and head control means for controlling the conduction time of the thermal head on the basis of the correction accumulated-heat magnitude.