Roland VersaCamm VS-640 Service Notes page 264

CROP MARK SENSOR
It detects the Crop Mark.
INK EMPTY SENSOR
It detects whether the Ink Cartridge is
empty or not.
PINCH ROLLER SENSOR
It detects the positions of Pinch Roller.
INK CARTRIDGE IC SENSOR
It communicates with the IC chip of the Ink
Cartridge.
INK CARTRIDGE SENSOR
It detects whether the Ink Cartridge is installed
or not.
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