Data processing method for eliminating influence of heat accumulating in thermal head

摘要

A data processing apparatus for correcting heating data for a thermal head to eliminate influence of heat accumulation in the thermal head on recording density. The apparatus is comprised of a correction circuit having a subtracter for subtracting first correction data from original heating data of a subject line to print, in pixel-to-pixel correspondence; and first to Nth operation circuits provided in correspondence with first to Nth heat accumulating layers of the thermal head respectively. The first operation circuit has a register storing first heat accumulation data for one line, a multiplier for multiplying the stored first heat accumulation data by a coefficient to provide the first correction data; a multiplier for multiplying the original or the corrected heating data of the subject line by a coefficient to provide a first value for each pixel of the subject line; a multiplier for multiplying the stored first heat accumulation data by a coefficient to provide a second value for each pixel of one line; and an adder for adding the first and second values in pixel-to-pixel correspondence. A new series of first heat accumulation data is obtained from output data of the first adder, and is stored in the register in place of the previously stored first heat accumulation data. The Jth operation circuit, J being 2 to N, has the same construction as the first operation circuit, and prepares Jth heat accumulation data based on previously stored Jth and (J-1)th heat accumulation data, to provide Jth correction data based on the Jth heat accumulation data.