Epson Stylus Pro 9500 Service Manual page 67

EPSON Stylus Pro 9500 Revision A
2.1.2.5 Printhead Driver Circuit
The EPSON Stylus Pro 9500 uses the same printhead as that of the EPSON
Stylus Pro 5000 (both dark-color head and light-color head), and the basic
configuration of the driver control circuit is also the same.
Print data is rasterized on the memory (DRAM). Triggered by the LAT signal
(BHLAT, CHLAT), the IC13 reads the print data in the format and the order
according to the print mode, and transfers the data to the printhead (driver
circuit on the printhead) synchronizing with the clock signal (BHCLK, CHCLK).
The IC13 is equipped with the counter function, which keeps count of each
color's data "1" being transferred to the printhead, and the accumulated count
is used to calculate the ink consumption.
The waveform signal is processed at the IC13. Triggered by the input of the
PTS signal from the CPU (IC8), the waveform signal is input into the DAC in
the IC37 as 10-bit data, synchronizing with the clock signal (20mHz). The DAC
then converts the head driver voltage waveform data to analog data, and
outputs it to the trapezoid waveform generation circuit (common driver).
The driver circuit on the printhead (nozzle selector) receives the serial data on
nozzle selection ("H" level = printing nozzle / "L" level = non-printing nozzle)
from the IC13. The circuit then latches the data to the data latch using the LAT
signal, and selects the printing nozzles and non-printing nozzles. Once the
Figure 2-25. Printhead driver circuit
nozzles are selected, the trapezoid waveform generation circuit (common
driver) generates the trapezoid waveform to fire ink. The NCHG signal
(BHNCHG, CHNCHG), which is input into the printhead from the IC13,
prepares all the nozzles for the next firing by applying slight vibrations during
the non-printing phase.
Operating Principles Component List & Illustrations 67