40718401TH Rev.5 35 /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 (MSM6731BWAF or MSM6732BWAF) together as a pair.The LED correcting head consists of the correction control LSI (MSM6730WAF), LED drivers(MSM6731BWAF or MSM6732BWAF), and an LED array. The block diagram of the LED correctinghead is shown below.The existing LED head receives the printing data from the CPU directly at its LED drivers. With the LEDcorrecting head, a correction control LSI (MSM6730WAF) is connected between the CPU and LEDdrivers, so the printing data is input to the LED drivers through the correction control LSI. In order tomaintain compatibility with the existing LED head, the printing operation of the LED correcting head iscarried out through identical sequence.The LED correcting head is a 600 dpi head, with the LED drivers located on both sides of the LED arraywith a 300 dpi pitch spacing. The printing and correction data obtained from the CPU through four signallines are sent to the LED array.STRB1-NSTRB2-NSTRB3-NSTRB4-NLOADICLOCKIDATAI0DATAI1DATAI2DATAI3MSM6730WAFEEPROMCorrectionValuesLED LED LED LED LED LED LEDLED DriverMSM6732BWAFLED DriverMSM6732BWAFLED DriverMSM6731BWAFLED DriverMSM6731BWAFLED ArrayPrinting and correction data combined signal lineCorrection data signal lineFromCPU
