41356901TH Rev.2 37 /2.3.4 Revision of LED Head IlluminationAn LED correcting head, which is capable of correcting the illumination of the LED for each dot, is beingused in this printer. LED illumination correction function of 16 steps is carried out by using an EEPROMwhich is installed in the LSI that maintains the LED illumination correction values, and an LED correctiondrivers together as a pair.The printing and correction data obtained from the CPU through four signal lines are sent to the LEDarray.The printing operation timing chart is shown below.CLOCKILOADIDATAI3~0STRB1I-NSTRB2I-NSTRB3I-NSTRB4I-NNormal Mode Printing Timing ChartFirst line printing data sent Second line printing data sentFirst line printingThe printing operation is carried out in normal mode. Under ordinary circumstances such as when thepower is turned on or when LOADI signal level is low, the normal mode is enabled.The printing operation is carried out in the following sequence. First, the printing data DATAI3 throughDATAI0 are stored, sequentially shifted, in the shift registers of the LED drivers, by the printing datasynchronous clock, CLOCKI. Then the printing data stored in shift registers are latched by the high levelpulse of LOADI. The latched printing data turns the LEDs on by STRB1I-N through STRB4I-N andactuates printing.
