Epson STYLUS COLOR 3000 Service Manual page 65

Operating Principles
Common driver circuit for the black printhead
Gate array E05B33 (IC6) sends serial data to the printhead nozzle selector circuit on the printhead to select
nozzles to be activated. Then with data transferred from the gate array, the common driver on the control
board drives the PZTs corresponding to each nozzle. The operating principles for the black printhead are:

Nozzle selector circuit
Nozzles for the black printhead are divided into 2 blocks with 64 nozzles each, and 2 different types
of nozzle selection signals (BAHDATA and BBHDATA) that are sent in serial data to the
corresponding blocks. The clock signal (BHCLK) is composed of pulses #1 to #64. The nozzles to be
activated are determined when the latch signal (BHLAT) synchronizes the nozzle selection signal
with the clock signal. However, the pulse number and the selected nozzle number are unrelated.

Common driver circuit
The common voltage (VH) and the rank value correspond to the black printhead's characteristics and
ID. This value is stored in advance in the EEPROM when the printer is off. When the printer is 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 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 signals to prevent changes in temperature and ink
viscosity.
BAHDATA
BBHDATA
BHNCHG
BKC,BCHG
2-24
#1
BHCLK
BHLAT
Rank Value*
VH
BND0/1
BMD0/1
* Rank Value: The period of time in which the signal COM stays HIGH.
Normal value is approximately 8 ms.
Figure 2-21. Black Data Transmission Timing
#64
Printhead Drive Voltage (VH)
EPSON Stylus Color 3000 Service Manual