Printhead Driver Circuit - Epson Stylus C50 Service Manual

EPSON Stylus C50/C60/C61/C62

2.2.2.2 Printhead Driver Circuit

The printhead driver circuit consists of the following two components:
Head common driver circuit (Common driver IC9/IC19 & Wave amplifier
transistor Q2, Q3)
Nozzle selector IC on the printhead driver.
The common driver (IC9/IC19) generates a basic drive waveform according to the
output signals from CPU (IC1). The basic drive waveform is amplified by the
transistors Q2 and Q3 (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 Q2 and Q3. See Refer to Figure 2-21 for the printhead driver
circuit block diagram.
Head common driver circuit
The basic drive waveform is generated in the common driver (IC9/IC19) based on
the following 12 signal lines output from the CPU (IC1); 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 (IC9/IC19). 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 Q2 and Q3 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 (IC1). 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.
Operating Principles
CPU
(IC1)
HWA0
HWA1
HWA2
HWA3
HWA4
HWCLK1
HWCLK2
HWFLR
HWRST
HWSDATA
HWSCLK
HWSLAT
HSOCLK
HCH
HSO1 ~ HSO6
HSOCMD
HLAT
HNCHG
C-P32
C-P13
C-P30
C-P34
C-P12
C-P40
Electrical Circuit Operating Principles
+4.2V
Common
Driver(IC19)
19 F1
VCC45
132 26
AO
133
25
A1
134
24 17
A2 Q2
NPNB
15
135
23
A3
FB
136 14
22
Q3
A4
PNPB
127
3
CLK1
126 4
CLK2
125
5
FLOOR
124
6
RST
130
27
DATA
129
28
DCLK
128
1
E
13
12
21
24
19
20
8
11
10
18
9
6
Figure 2-21. Printhead driver circuit
Revision C
+3.3V
Nozzle
Selector IC
15
COM
13
COM
CN9
11
SCK
9
CH
2
SI1 ~ SI6
Head
1
SP
Drive
Pulse
2
COM
4
VHV
8
LAT
6
NCHG
10
CSCK
11
CN8
COI
12
CRST
14
CSDA
15
CVDD
13
THM
48