Canon iPF825, Service Manual

Page: 93 / 316

Chapter 2
2-23
2.3.2.3.2 Structure of Carriage Unit
0020-5492
a) Printhead mount
The printhead is secured to the carriage by the printhead fixer cover and the printhead fixer lever.
When the printhead is secured to the carriage, the signal contact of the head relay PCB is pressed against that of the printhead to convey print signals.
Furthermore, the ink passage from the ink tanks is connected to the printhead via the ink tubes.
b) Ink port
Ink is supplied to the printhead via an ink tube, which is connected to ink joints, and runs between the tube guides to reach the carriage and follow its movement.
F-2-11
c) Controller
The Carriage relay PCB is connected to the head relay PCB by means of a short flexible cable.
The flexible cable between the main controller and the carriage relay PCB follows up the motion of the carriage together with the tube guide.
A photocoupler encoder mounted in the lower part of the back of the carriage detects a linear scale reading as the carriage moves.
d) Carriage drive
Mechanical misregistrations in the vertical/horizontal and bidirectional print positions of the printhead mounted can be corrected by selecting Adjust Printer from
the main menu to shift the print timing.
A DC-operated carriage motor drives the carriage reciprocally on the platen by way of the carriage belt.
The carriage home position, or the capping position, is detected by the sensor flag on the right side of the carriage and the photointerrupter-based carriage HP sensor
on the right side of the printer. When the linear scale position is set as a reference home position for use in subsequent position control operations, the carriage motor
is driven by a control signal generated from the main controller PCB.
e) Printhead maintenance unit
This printer cleans the printhead with the carriage halted at its home position.
Wiping takes place through the rotation of the motor.
Wiper blades mounted on the carriage wipe the printhead while the carriage is halted at its home position.
Wet wiping is carried out for added wiping removal performance, whereby the wiper blades are moistened with glycerin as they are pressed against an absorber
impregnated with glycerin.
Maintenance jet ejection is carried out on the cap, at the maintenance jet tray, borderless printing ink tray and on the paper surface.
A suction operation is carried out by a suction cap in the purge unit.
f) Carriage height adjustment unit
The head height is adjusted with the carriage halted at its home position.
The lift motor is driven to rotate the lift shaft within the carriage, in sync with which the lift cams on both sides of the carriage move the head holder up and down,
thereby varying the separation between the face of the printhead and the paper.
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
[1] Linear scale [5] Carriage
[2] Printhead fixer lever [6] Ink tube unit
[3] Printhead fixer cover [7] Carriage motor
[4] Electrical contact
[7]
[3]
[5]
[2]
[1]
[4]
[6]