Epson Stylus COLOR 3000 Service Manual - Page 65

Operating Principles Color printhead nozzle selector circuit The operating principle for the color printhead is the same as for the black printhead except that color print is performed with data for 3 different colors: yellow, cyan, and magenta. The operating principle for the color printhead is as described below: Nozzle selector circuit The nozzles for the color printhead are divided into 3: for yellow, cyan, and magenta with 64 nozzles for each of them. The nozzle selection signals for each color (YHDATA for yellow, MHDATA for magenta and CHDATA for magenta) are sent simultaneously in serial data. The clock signal (CHCLK) is composed of the pulses from #1 to #64. The nozzle selection signal and the corresponding clock signal are synchronized by the latch signal (CHLAT) to determine the nozzle to use. 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 color printhead characteristics. This value is stored in advance in the 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 and outputs the serial data SCDATA 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 2-22. Color Data Transmission Timing 2-24 Rev. A