Epson Stylus COLOR 3000 Service Manual - Page 64

EPSON Stylus COLOR 3000 Common driver circuit for the black printhead Gate array E05B33 (IC6) sends serial data to the head nozzle selector circuit on the printhead to select nozzles to be activated. Then the data is transferred to the common driver on the control board to drive all PZT that correspond to each nozzle. The operating principles for the black printhead is as follows: Nozzle selector circuit Nozzles for the black printhead are divided into 2 rows with 64 nozzles on each, and 2 different types of nozzle selection signal (BAHDATA and BBHDATA) are sent in serial data to the corresponding row. Clock signal (BHCLK) is composed of the pulses from #1 to #64. The nozzles to be activated are determined by the nozzle selection signal synchronized with the clock signal by the latch signal (BHLAT). However, the pulse number and the selected nozzle number have no relevance. Common driver circuit The common voltage ( ) and the rank value are established to correspond to each of the black printhead characteristics. This value is stored in advance in the EEPROM when the printer power is off. At power on, the value is stored in the RAM. The gate array E05B33 (IC6) refers to this value when transferring the serial data SBDATA to the common driver circuit as the voltage control signals. The serial data transmission control signals (SCLK, SSTB and SCLR) are used for this operation. The thermistor controls the common voltage by outputting the signals to compensate for changes in ink viscosity. Figure 2-21. Black Data Transmission Timing Rev. A 2-23