Canon iPF825, Service Manual

Page: 89 / 316

Chapter 2
2-19
2.3.2 Ink Passage
2.3.2.1 Ink Passage
2.3.2.1.1 Overview of Ink Passage
0020-5486
The ink passage houses the ink tank, printhead, caps, maintenance cartridge, waste ink collector, ink tubes interconnecting the mechanical units, suction pump driv-
en mainly for sucking inks and so on. Its functions include supplying, circulating and sucking inks.
The ink passage (per color) is schematically shown below, along with the ink flow.
F-2-8
a) Supplying inks from the ink tanks to the ink supply valve assembly
The each ink tanks contain ink to supply to the printhead.
Ink of the ink tanks is supplied to the subtanks and then ink of the subtanks is supplied to the ink supply valves by the fluid level difference.
On this occasion, air is discharged through the air passage of the subtanks to keep the internal pressure of the ink tanks constant.
b) Supplying inks from the ink supply valves to the printhead
Ink is filled from the ink tank to the printhead by driving the suction pump after the ink supply valve is opened and the printhead is capped.
The ink sucked from the caps flows to the maintenance cartridge.
c) Supplying inks while printing
The ink supply valves are kept open while printing, so that ink is constantly supplied to the printhead according to the negative pressure of the nozzle assembly
which is caused by the discharging inks.
Furthermore, waste inks sucked by the cleaning operation flow into the maintenance cartridge.
If opening all ink passages (that is, when the ink tank is not installed, ink supply valve is opened and printhead fixer lever is opened) while the ink tube is filled by
ink, ink in the ink tube flows backward according to the fluid level difference.
As a precaution, never open all the ink passages at the same time while the ink tubes are being filled with inks.
d) Ink agitating
Ink will be agitated to prevent the element of the pigment ink from subsiding in the ink tank and the sub-tank.
The valve motor drive is transmitted to the agitation cam, the agitation fin in the sub-tank rotates and ink in the sub-tank will be agitated. In addition, ink in the ink
tank circulated by moving the piston under the needle(ink supply) up and down.
Maintenance cartridge
Ink tank
Ink supply vavle
Joint
Joint
Carriage unit
Printhead
Cap
Suction pump
Mechanical Drive Unit
Ink or air flow
Subtank
Agitation fin
Needle(ink supply)
Piston
Needle(air passage)
Valve
motor
Agitation
cam