Epson Stylus 1500, Service Manual

Page: 66 / 185

Color Printing
Common Driver Circuit
The common voltage (VH) used for color printing corresponds to the specific characteristics of the
color printhead. This value is stored in patterns ID1 - ID4 in each printhead’s driver circuit. After
you install the color printhead unit in the carriage unit, the printhead transmits the ID data to the
C172 MAIN board. Gate array E05B16 (IC2) outputs the parallel data for the voltage control signals
(CHPWMO) to the common driver circuit, referring to this value. The common voltage is then
established at one of 15 levels, using 24 V as the center value.
Head Driver Circuit
Gate array E05B16 (IC2) converts the print data into serial data and outputs it from port BHSO (pin
56) to the black head driver circuit. Head driver SED5619D then latches the head data when the
E05B16 gate array outputs the CHLAT signal, and the latched data becomes 60-bit parallel data for
the color head. One bit corresponds to each nozzle.
When data transfer and nozzle selection are complete, gate array E05B16 outputs the color head
charge pulse (CH2C) and discharge pulse (CH2D1/0) to the common driver circuit. The common
driver circuit then generates the trapezoidal pulse and applies it to the printhead as a common
driver pulse. After this, the nozzle selected by the head data is activated to eject the ink.
ID 1
I D 2
T H
C O M
G N D 2
I D 3
M / C
I E
G N D
S I
C L O C K
G N D
I D 4
C O
L A T C H
F G
G N D
V D D
Figure 2-28. Color Printhead Connector Pin Alignment
COM
CHLAT
C H SO
CHCLK
# 1
# 6 4
C H 2 C
CH2D1/0
V H
Figure 2-29. Color Data Transmission Timing
Operating Principles
EPSON Stylus 1500 Service Manual 2-25