Epson Stylus PHOTO 950 Service Manual page 48

EPSON Stylus PHOTO 950
Head common driver circuit
The reference head drive waveform is produced in the common driver (IC9) based
on the following 10 signal lines output from the ASIC (IC6); A0-A4, CLK1,
CLK2, FLOOR, RST, and DATA.
By the DATA signal output from the CPU (IC6), the original data for the head
drive waveform is written in the memory in the IC11. The addresses for the written
data are determined by the A0 to A4 signals, and, of among, data used to
determine the waveform angles is selected. Then, setting the selected data,
producing trapezoid waveform value, and canceling the data are performed by the
rising edges of the CLK1 and CLK2 signals.
Head nozzle selector circuit
Printing data is converted into serial data by the CPU (IC6). Then the converted
data is allocated to the six rows, the number of the head nozzle rows, to be
transferred to the nozzle selector through the seven signal lines (HS01 to HS07).
Data transmission from the CPU (IC6) to the nozzle selector synchronizes with the
LAT signal and SCK clock signal. Referring to the transferred data, nozzles to be
activated are selected, and the Puts of the selected nozzles are driven by the drive
waveform output from the head common driver.
OPERATING PRINCIPLES
2.3.2.2 Reset / EEPROM Circuit
RESET CIRCUIT
Reset circuits consist of the rest IC (IC12). Reset circuits are mounted on the MAIN
board to monitor the two voltages: +5V for the logic line and +42V for the drive line.
When each circuit detects abnormality on the corresponding line, it outputs a reset
signal to reset CPU (IC6). This function is necessary to prevent the printer from
operating abnormally. This IC monitors both +5V and +45 lines but can reset them
independently. The reset circuits outputs reset signal when +5V line becomes 4.2V or
lower or +42V line becomes 36.3V or lower.
Unlike the previous products, Stylus PHOTO 950 has no timer IC and no Lithium
battery on the main board.
Main signal lines are explained below;
OUT1
OUT2
IN
VCC
Electrical Circuit Operating Principles
: Interrupt
: Reset line
: +42V line monitoring line
: +5V line monitoring line
Revision A
48