Service manual

2.3.2.2 Sensor Circuits
The following sensor circuits enable the C184 MAIN board to monitor printer mechanism status:
HP sensor A photocoupler-type HP (home position) sensor is attached to the surface of the printer
mechanism to detect the carriage home position. A HIGH level from the signal indicates
that the carriage is in home position.
PE sensor A mechanical switch PE (paper end) sensor is built into the printer mechanism to determine
whether there is paper in the printer or not. A LOW level from the signal indicates that no
paper is loaded.
BCO sensor,
CCO sensor
Micro switches (BCO sensor for the black ink cartridge, CCO sensor for the color ink
cartridge) are attached to the bottom of ink cartridge holder in the carriage unit. When the
ink cartridge is installed, these switches are pressed and a LOW level from the signal
indicates that the ink cartridge is installed into the ink cartridge holder. These sensing
timing is only in the cartridge installation mode and one minute after the carriage holed to
prevent from miss censoring owing from switch actuators shock in printing condition.
Thermistor A thermistor is attached to the color printhead driver board to monitor its temperature using
the thermistor’s resistance value (at 25° C (77° F), the normal value is approximately
10K Ω). The CPU changes the printhead drive signal’s pulse width (charge pulse width)
based on the temperature level.
TH
(CN12)
CCO
181
CPU (IC1)
SWA0
HP
PE
(CN8)
(CN9)
180
BCO
(CN11)
GA (IC2)
AN0
86
SWC1
SWC2
(CN12)
4
3
SWC0
5
PB3
Figure 2-3. Sensor Circuit Block Diagram
Operating Principles Stylus Pro XL+ Service Manual
2-4 Rev.A