Printhead Driver Circuit - Epson Stylus C110 Service Manual

EPSON Stylus C110/C120/D120

2.3.2.2 Printhead Driver Circuit

The printhead driver circuit consists of the following two components:
Head common driver circuit (Head driver IC11 & Wave amplifier transistor
Q3, Q4)
Nozzle selector IC on the printhead driver
The common driver (IC11) generates a basic drive waveform according to the output
signals from CPU (IC8). The basic drive waveform is amplified by the transistors Q3
and Q4 (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 Q3 and Q4.
Refer to Figure 2-20 (p.38) for the printhead driver circuit block diagram.
Head driver circuit
The basic drive waveform is generated in the head driver (IC7) based on the
following 12 signal lines output from the CPU (IC8); DATA0-DATA9, LAT, and
PSAVE. By the DATA signal output from the CPU, the original data for
generating the head drive waveform is written in the memory in the head driver
(IC7). The addresses for the written data are determined by DATA0-DATA9
signals. Then, the necessary data is selected from the address and appropriate basic
drive waveform is generated. The generated head drive waveform is transmitted to
the nozzle selector IC on the printhead driver board through the transistor Q3 and
Q4 and applied to the nozzle PZT specified by nozzle selector IC.
Nozzle selector circuit
A print data is converted into serial data by the CPU (IC8). The serial data is
divided into three for allocating data to each of the three head columns, and
transmitted to the nozzle selector via three signals (HS01 to HS03). The data
transmission from the CPU (IC8) to the nozzle selector synchronizes with the LAT
signal and SCK clock signal. Nozzles to be used are determined depending on the
transmitted data and PZT for the selected nozzles are controlled by the waveform
output from the head driver.
OPERATING PRINCIPLE
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Electrical Circuit Operating Principles
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CPU Head driver
(IC8) (IC7)
22
C10
4
VCC45
HDAC_D0
DATA0
C11 3
HDAC_D1
DATA1
C12 2
HDAC_D2
DATA2
D13
1
HDAC_D3
DATA3
C13 30
20
HDAC_D4
DATA4
NPNB
A12 29
HDAC_D5
DATA5
28
B12 18
HDAC_D6
DATA6
FB
A11 27 16
HDAC_D7
DATA7
PNPB
B11 26
HDAC_D8
DATA8
D10 25
HDAC_D9
DATA9
B13 5
HDAC_CLK
LAT
J3
23
PSAVE
PC1
C2
HCH
B1
HSOCLK
C1
HS03
B3
HLAT
A2
NCHG
B2
HS01
A1
HS02
C9
AIN1
Figure 2-20. Printhead Driver Circuit Block Diagram
Revision B
Nozzle
selector IC
+42V
18 VHV
F1 F2
CN6
Q3
COM
17
Q4
13
COM_3
CHA
8
CN5 6
SCK
3
TH
7
VHV
14 SI3
5 COM_3
3
COM_2
1 COM_1
CN7
8 LAT
6
NCHG
4 SI1
2 SI2
+3.3V
Head
drive
pulse
38