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EPSON Stylus PHOTO 810/820/830 Revision B
Operating Principles Electrical Circuit Operating Principles 55
2.2.3.2 Printhead Driver Circuit
The printhead driver circuit consists of the following two components:
Head common driver circuit (Common driver IC10 & Wave amplifier
transistor Q1, Q2)
Nozzle selector IC on the printhead driver.
The common driver (IC10) generates a basic drive waveform according to the output
signals from CPU (IC8). The basic drive waveform is amplified by the transistors Q1
and Q2 (the amplified one is called drive waveform.) and then transferred to the nozzle
selector IC on the printhead driver board. Print data is converted to serial data by the
CPU and then sent to the nozzle selector IC on the printhead driver board. Based on the
serial data, the nozzle selector IC determines the nozzles to be actuated. The selected
nozzles are driven by the drive waveforms amplified by the transistor Q1 and Q2. See
refer to Figure 2-26 for the printhead driver circuit block diagram.
Head common driver circuit
The basic drive waveform is generated in the common driver (IC10) based on the
following 12 signal lines output from the CPU(IC8); A0-A4, CLK1, CLK2,
FLOOR, RST, DATA, DCLK, and E.
By the DATA signal output from the CPU, the original data for the basic drive
waveform is written in the memory in the common driver (IC10). The addresses
for the written data are determined by A0-A4 signals. Then, the necessary data is
selected from the address and appropriate basic drive waveform is generated.
Generated basic drive waveform is transferred to nozzle selector IC on the
printhead driver board through the transistor Q1 and Q2 and applied to the nozzle
PZT specified by nozzle selector IC.
Nozzle selector circuit
Printing data is allocated to the six rows (the number of the head nozzle rows) and
converted into serial data by the CPU (IC8). Then the converted data is transferred
to the nozzle selector IC through the six signals lines (HS01 to HS06). Data
transmission from the CPU to the nozzle selector synchronizes with the LAT
signal and SCK clock signal. Based on the transmitted data, appropriate nozzle is
selected and the PZTs of the selected nozzle are driven by the drive waveform
output from the head common driver.
Figure 2-26. Printhead driver circuit
CPU
(IC8)
Common
Driver(IC10)
Nozzle
Selector IC
+42V
Head
Drive
Pulse
CN9
CN8
HWA0
HWA1
HWA2
HWA3
HWA4
HWCLK1
HWCLK2
HWFLR
HWRST
HWSDATA
HWSCLK
HWSLAT
HSOCMD
HSO3
HSO2
HSO1
HNCHG
HLAT
C-P34
HSO6
HSO5
HSO4
HSOCLK
HCH
C-P13
C-P30
C-P12
C-P32
C-P49
COM
COM
SP
AO
A1
A2
A3
A4
CLK1
CLK2
FLOOR
RST
DATA
DCLK
E
VCC45
NPNB
FB
PNPB
100
99
98
97
96
107
106
105
104
102
103
108
129
126
127
128
119
118
117
122
123
124
120
121
116
115
114
113
33
26
25
24
23
22
3
4
5
6
27
28
1
F1
+3.3V
19
17
15
14
Q1
15
13
1
4
3
2
F2
Q2
7
6
SI3
SI2
SI1
NCHG
LAT
CSDA
SI6
SI5
SI4
5
SCK
11
9
CH
6
8
14
COM
2
VHV
4
GND2
GND2
GND2
1
3
COI
CRST
CVDD
CSCK
THM
11
12
15
10
13