Epson Stylus Photo 720, Service Manual

Page: 46 / 154

EPSON Stylus Photo 720 / EPSON Stylus Photo EX3 Revision A
Operating Principles Electrical Circuit Operating Principles 46
Figure 2-14. Printhead Driver Circuit
o
Head common driver circuit
The reference head drive waveform is produced in the common driver (IC15)
based on the following 12 signal lines output from the ASIC (IC2); A0-A4, CLK1,
CLK2, FLOOR, RST, DATA, DCLK, and E.
Based on the DATA signal output from the ASIC (IC2), the original data for the
head drive waveform is written in the memory in the common driver (IC15). The
addresses for the written data are determined by the A0 - A4 signals, and, of
among, data used to determine the waveform angles is selected and appropriate
head driver waveform is generated. Generated head driver waveform is transferred
to nozzle selector IC on the head driver board and applied to the nozzle PZT
specified by nozzle selector IC.
o
Head nozzle selector circuit
Printing data are allocated to the six rows, the number of the head nozzle rows, and
converted into serial data by the ASIC (IC2). Then the converted data is
transferred to the nozzle selector IC through the seven signal lines (SI0 to SI6).
Data transmission from the ASIC to the nozzle selector synchronizes with the
SCK clock signal and the LAT signal. Referring to the transferred data, nozzles to
be activated are selected, and the PZTs of the selected nozzles are driven by the
drive waveform output from the head common driver.
V C C 4 5
V c c 4 5 _ 2
N P N B
F B
P N P B
V O U T G N D
F 1
V H C T L
2 2
2 0
C O C
S C K
C O B
T H M
1 6
1 5
1
1 1
3
7 9
S W C 0
6 5
A N 0
1 0 5
A 0
A 1
A 2
A 3
C L K 1
C L K 2
/ F L O O R
/ R S T
D A T A
D C L K
/ E
H W A 0
H W A 1
H W A 2
H W A 3
H W A 4
H W C L K 1
H W C L K 2
/ H W F L R
/ H W R S T
H W S D A T A
H W S C L K
/ H W S L A T
S I 1
1 2
H N C H G
+ 4 2
2 3
1 8
1 6
1 3
1 2
1 1
G N D 2
G N D 2
G N D 2
C O M
C O M
C O M
V H V
1 0
V C C 5
+ 5
2 4
1 4
S W C 1
8 0
6 6
N C H G
3
H S 0 1
S I 2
H S 0 2
1 0
S I 3
H S 0 3
8
S I 4
9
H S 0 4
S I 5
H S 0 5
7
S I 6 H S 0 6
H 0 6 4 F 2 3 2 8 F
( I C 1 )
G N D
G N D
G N D
G N D
1 3
6
4
5 6
5 8
5 9
6 2
6 3
5 0
5 1
5 2
5 3
5 5
5 4
4 9
2 8
2 7
2 6
2 5
3
4
5
6
2 9
3 0
1
H S O C L K
6 7
6 8
6 9
7 1
7 2
7 3
S P
5
7 4
H S 0 C M D
C N 9
E 0 5 B 7 0 * * ( I C 2 )
C X A 2 1 2 8 S ( I C 1 5 )
Q 2
Q 3
1 6
1 5
1 4
G N D
G N D
G N D
G N D
G N D
G N D
+ 5 V
V D D
C N 8