Epson Stylus Pro XL Service Manual page 21

Operating Principles
Common Driver Signals
The common driver control signals consist of the common voltage control signals (SBDAT/SCDAT, SSTB,
SCLR, SCLK) and the common drive pulse generation signals (BH1C0/CH1C0, BH1C1/CH1C1,
BH1D/CH1D, BHDIS/CHDIS). The common voltages (VH), ranging between the maximum voltage and 0
(V), are split into 256 levels, which are then translated into 8-bit serial data for the common voltage control
signal (BHDAT/CHDAT), which is output from gate array E05B21 to the common driver H8D2778A to fit
with each printhead specifically. The signals are received by SSTB, SCLR and SCLK to the common driver.
SCLT
SDAT
SCLR
SSTB
Figure 2-7. Common Driver Signal Timing Chart
After the common voltage (VH) is stabilized, common drive pulse generation signals are translated to
generate the common drive pulses from gate array E05B21 to the H8D2778A common driver.
C O M
BH 1C 0/C H 1C 0
BH 1C 1/C H 1C 1
B H 1 D / C H 1 D
2-8
Figure 2-8. Common Drive Pulses
Stylus Pro XL+ Service Manual
H
L
H
L
H
L
H
L
VH
Rev.A