Brother DCP6690CW Service Manual page 106

• The head thermistor detects the temperature inside the head/carriage unit. According to the
sensor information, the controller adjusts the head driver to compensate for changes in ink
viscosity.
• The carriage motor (CR) encoder sensor monitors the current position and speed of the head/
carriage unit. If the controller detects a head's travel speed error, it interprets the error state as
a paper jam or any foreign material getting into the carriage travel path and stops the
operation.
• The paper feed motor (PF) encoder sensor monitors the PF roller rotation angle and speed for
use in optimizing paper feed amount and speed.
• The Auto Sheet Feeder motor (ASF) encoder sensor monitors the rotation angle and speed of
the ASF motor shaft for use in optimizing paper pull-in amount and speed.
• The purge cam switch detects the drive positions of the purge cam.
• The cap lift cam switch detects the drive positions of the cap lift cam.
• The switchback paper detection sensor detects, in duplex printing, whether there is a
recording paper in the switchback paper path.
• The DX cover sensor detects whether the DX unit cover is properly closed.
• The DX cam switch turns ON or OFF depending on the position of the DX cam that drives the
DX flapper.
• The casing internal temperature thermistor monitors the temperature inside the machine. With
this thermistor signal, the controller determines the periodical automatic purge interval since
the casing internal temperature is almost equal to the ambient temperature of ink inside the
ink cartridges.
• There are four ink empty sensors, one for each color. The sensor actuator inside the ink
cartridge usually blocks the light path to indicate the presence of ink. When ink runs low
(near-empty state), the arm moves out of the beam, activating the sensor. The "Ink low"
message appears.
• There are four ink cartridge detection sensors, one for each color. The sensor detects whether
an ink cartridge is loaded.
The ON timing of the ink cartridge detection sensor and ink empty sensor enables the
controller to discriminate between a standard and large-volume ink cartridges.
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