Epson Stylus COLOR 3000, Руководство по обслуживанию, Страница: 64 / 180

EPSON Stylus COLOR 3000
Rev. A
2-23
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.
VH
BHLAT
BAHDATA
BHCLK
#1 #64
Rank Value*
BKC,BCHG
BHNCHG
BND0/1
BMD0/1
Head Drive Voltage (VH)
* Rank Value: The period of time in which the signal COM stays HIGH.
Normal value is approximately 8 ms.
BBHDATA
Figure 2-21. Black Data Transmission Timing