PRINTING DENSITY CONTROLLER

PURPOSE:To enable constant coloring density to be always realized whatever recording paper may be used by a method wherein a specific test pattern is printed each time thermosensible paper is exchanged, said density being detected and besides, a printing signal is controlled according to the density of detection. CONSTITUTION:Each time thermosensible paper is exchanged, a test pattern is printed for regulation of density, which is detected by a density sensor 43. A detection signal obtained according to the printing density of the test pattern is supplied to an A/D converter via an amplifier 71, and is converted to a digital signal. The digital signal is supplied to a pulse width setting circuit 73, and is variably controlled according to the printing density. This pulse width signal is stored in a memory provided to a thermal head control circuit 70, and input image information is printed out by the corrected pulse width. Therefore, variation in density of coloring capable of being generated by difference of a lot can always be equalized.