| 摘要 |
PURPOSE:To reduce density irregularity caused by the resistance value error of each heating element. CONSTITUTION:The resistance value Ri of each heating element is measured by a resistance value detection circuit 37 and subtracted from a standard resistance value R0 to calculate a resistance value error DELTARi. Fundamental bias data DB0i to which bias correction data correcting a bias heat energy error is added is calculated on the basis of the resistance value error DELTARi. Gradation correction data BD1i for correcting a gradation expression heat energy error is calculated by multiplying image dat DGi and gradation correction factor data DELTAR2i. The fundamental bias data DB0i and the gradation correction data DB1i are added by an adder.limiter 43 to calculate correction bias data DBCi. Correction bias heating is performed on the basis of the correction bias data DBCi. By this constitution, heating irregularity at the time of gradation expression heating is eliminated by the increase and decrease of the number of bias pulses and it becomes unnecessary to perform correction with respect to gradation data. |
