Epson Stylus PHOTO 2000P Service Manual page 54

EPSON Stylus PHOTO 2000P
Each sensor's functions and operating principles are as described below:
PE sensor
The PE sensor is located at the bottom right edge of the top frame in
the printer mechanism. It detects paper on the rear paper guide using
a photo sensor and PE sensor lever that are included in the sensor.
When paper is present, the PE sensor lever does not cut in between
the photo sensor terminals. So it outputs a LOW signal to the ASIC. If
there is no paper, on the other hand, the lever cuts in between the
photo sensor terminals. So it outputs a HIGH signal to the ASIC.
ASF sensor
The ASF sensor, located at the left edge of the ASF, detects ASF home
position. This sensor consists of the ASF HP detector wheel and a
transmission photo sensor. A small portion of the ASF HP sensor has
a cutout, and when the cutout comes into position between the photo
diode terminals, that condition is detected as ASF home position. In
this status, since the photo diode terminals are not blocked by the
wheel, a LOW signal is output to ASIC. Otherwise, a HIGH signal is
output. Referring to the ASF home position detected by this sensor,
the printer drives the ASF/Pump motor to set the LD roller and paper
return lever ready to the paper loading position.
Ink cartridge sensor (CSIC connector on the head board)
Ink cartridge sensor detects whether a black or color ink cartridge is
installed. Installation condition is determined depending on the
CSIC's connection. When a cartridge is installed, i a LOW signal to
ASIC is output. On the other hand, a HIGH signal is output when a
cartridge is out.
Head thermistor
The head thermistor is directly attached on the head driver board. It
monitors the temperature around the printhead and feeds back the
temperature to the CPU analog port. The printer refers to this
information to control head driver voltage based on the ink viscosity.
PF motor encoder
The PF motor encoder includes the loop scale attached to the left end
of the PF roller shaft and the transmission photo sensor. The
minimum resolution of the sensor is 1/180 inches. The sensor outputs
HIGH signals for the black lines and LOW signals for the transparent
parts to the ASIC. The printer controls the PF motor based on the
signals output from this sensor.
OPERATING PRINCIPLES
CR motor encoder
CR motor encoder consists of the transmission photo sensor
assembled in the CR unit and the linear scale attached along the CR
scanning line. The minimum resolution of the sensor is 1/180 inch. It
outputs HIGH signals for the black bands and LOW signals for the
transparent parts of the linear scale to the ASIC. The printer controls
the CR motor based on the signals output from this sensor. CR home
position is also detected based on the signals from this sensor.
Electrical Circuit Operating Principles
Revision A
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