Canon imagePROGRAF IPF8400 Service Manual page 81

The printhead height is detected from the lift cam sensor within the carriage and the distance of rotation of the lift motor.
g) Multi sensor
The multi sensor attached to the lower left part of the carriage consists of four LEDs and four light-receiving sensors to detect the leading edges and width of paper
and skews in it, and to adjust its registration and head height.
The multi sensor reference has the white plate attached to it, so that a reference value can be calculated during carriage height measurement by measuring the in-
tensity of light reflected upon the white plate.
(Service mode: SERVICE MODE>ADJUST>GAP CALIB)
h) Rail cleaner
The shaft cleaner located in the right rear of the carriage helps keep the main rail clean.
i) Internal unit temperature sensor
One thermistor is installed on the head relay PCB on the back of the head holder to detect the internal unit temperature.
[10]
[1]
[2]
[3]
[8]
[1] Carriage relay PCB
[2] Multi sensor
[3] Head relay PCB
[4] Lift cam sensor
[5] Sensor flag
[6] Lift cam
[5]
[4]
[9]
[11]
F-2-12
[7] Shaft cleaner
[8] Maintenance jet tray
[9] Carriage HP sensor
[10] Multisensor reference
[11] Head management sensor unit
[12] Lift motor
Chapter 2
[7]
[6]
[12]
2-15