Printhead Driver Circuit - Epson Stylus PHOTO 890 Service Manual

EPSON Stylus Photo 890/1280/1290

2.2.2.1 Printhead Driver Circuit

The printhead driver circuit includes:
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Common driver IC10 (E09A14RA)/IC11 (E09A15KA) directly attached to
the C393MAIN board.
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Nozzle selector IC (IR2C95F or SED6125T0A) on the head board.
The common driver generates reference drive waveforms according to the output
signals from ASIC on the C393MAIN board. The reference drive waveforms are
amplified by the transistors Q2 and Q3 and then transferred to the nozzle selector IC on
the head board. Print data is converted to serial data by the ASIC and then also sent to
the nozzle selector IC on the head board. Based on the serial data, the nozzle selector
IC determines the nozzles to be actuated. The selected nozzles (PZT) are driven
according to the drive waveforms produced by the common driver. See Figure 2-16 for
the printhead driver circuit block diagram.
Figure 2-16. Printhead Driver Circuit
OPERATING PRINCIPLES
o
Head common driver circuit
The head common driver IC10 (E09A14RA)/IC11 (E09A15KA) generates
reference head drive waveforms according to the output of the following 9 signal
lines: A0-A4, CLK1, CLK2, RST, FLOOR, and DATA.
By the DATA signal output from the IC19 ASIC (E01A20CA**), the original data
for the head drive waveform is written in the memory in the IC10/IC11. Addresses
for the written data are determined by the A0 - A4 signals, and, of among, data
used to determine the waveform angles is selected. Then, setting the selected data,
producing trapezoid waveform value, and canceling the data are performed by the
rising edges of the CLK1 and CLK2 signals.
o
Head nozzle selector circuit
Print data is converted into serial data by the ASIC (E01A20CA**). Then the
converted data is allocated to the six rows, the number of the head nozzle rows, to
be transferred to the nozzle selector IR2C95F (Sharp) or SED6125T0A (EPSON)
through the six signal lines (HS01 to HS06). Data transmission from IC19 ASIC
(E01A20CA**) to the nozzle selector synchronizes with the LAT signal and SCK
clock signal. Referring to the transferred data, The nozzle selector IC selects the
nozzles to be activated, and the PZTs of the activated nozzles are driven by the
drive waveforms output from the head common driver.
Electrical Circuit Operating Principles
Revision C
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