Epson Stylus Color 980 Service Manual page 68

EPSON Stylus Color 980
Encoder:
This sensor increases accuracy of ink ejection timing. Irregular
movement of the carriage, usually caused by a paper jam, can be
also detected based on the change in input signals of this sensor.
Carriage movement is monitored by running the encoder belt (with
lines printed on it with increments of 180 dpi) between the photo
sensor attached to the carriage. Also, if the printer receives a large
impact during printing, the input signal cat not be properly read, and
in some cases print quality decreases with a dot missing problem.
This is because this printer forms one dot by producing trapezoidal
head driving waveform based on the cycle determined by the
signals sent from the encoder.
Ink cartridge sensor:
If the printhead drives without any ink cartridge installed (= false
firing), it damages the printhead unit. Also, compared with other
printers, this printer uses the largest number of PZT and accordingly
releases more heat. For this reason, the ink itself inside the
cartridge serves to lower the temperature inside the cartridge, and
black and color ink cartridges can be separately detected to avoid
false firing.
Detection process: An ink cartridge is detected when the ink
cartridge being installed activates the actuators, which then pushes
the micro switch.
CR home position sensor:
When the printer is turned on, the CRHP sensor confirms the CR is
in the home position during the home position seeking sequence.
Then the printer can determine the CR control afterwards. The
printing column position is also confirmed based on the signals from
the sensor.
Detection process: The carriage is detected when the flag interrupts
the light beam in the photo sensor which is located on the right end
of the printer mechanism.
Operating Principles
PE (Paper End) sensor:
The PE sensor detects the following conditions:
ASF sensor:
Various parts in the ASF are engaged in the phase that is designed
to feed paper at the appropriate timing. If the timing is wrong, mis-
match occurs between paper feeding by the ASF and paper
transportation for printing, and non-feeding or paper jam will occur.
Therefore, this printer monitors the sensor condition at power on
and before and after paper is fed/ejected according to the pump/
ASF motor's rotational distance.
Power on/off detection:
Unlike primary-side switch type products, ASIC E05B60 (IC3) on the
C380 main board is used to monitor the power on/off operation
instead of any sensor. When the power switch on the control panel
is turned off, the change from 5 V to ground level is detected at the
Pin 33 of the IC3, and the program starts the power off sequence
with this change. Power used during the sequence is supplied by
the electrolysis condenser C84 in the voltage drop delay circuit in
the secondary side of the C265 PSB/PSE board. The electrolysis
condenser continues to supply power until all electric charge inside
is completely discharged.
Electrical Circuit Operation Principles
Whether or not paper is set at power on.
Whether or not paper is properly fed from the ASF with the
paper feed command.
Whether or not the printer properly ejects a page of printed
paper after rotating the PF (Paper Feed) motor with the
predefined distance.
Detection method: A photo sensor is used to detect the
actuator's motion; the actuator is pushed/released by the
leading/rear edge of the paper.
Revision A
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