Ink Tank Unit; Structure Of Ink Tank Unit - Canon W6400 Series Service Manual

Chapter 2
a) Ink supply from ink tank to ink supply valve
The ink tank contains ink which is supplied to the printhead.
Ink flows from the ink tank to the ink supply valve due to the fluid level difference.
b) Ink inflow from ink tank to sub buffer
Although ink flows from the ink tank to the sub buffer due to the fluid level difference, air also enters from the air passage of the sub buffer to maintain
the pressure inside the ink tank at a fixed level. If the ink inside the sub buffer exceeds a certain level, the ink passes through the air passage and flows to
the maintenance cartridge.
c) Ink supply from ink supply valve to printhead
Ink is supplied from the ink tank to the printhead by opening the ink supply valve, capping the heads, and then driving the suction pump. The ink removed
from the caps flows to the maintenance cartridge.
d) Ink supply during printing
During the printing operation, ink is constantly filling the printhead from the ink tank due to the negative pressure applied to the printhead nozzle by the
opening of the ink supply valve and discharging of the print ink.
Waste ink removed by the cleaning operation and waste ink in the maintenance jet tray flows to the maintenance cartridge.
If all of the ink passages are opened (ink tank is not installed, ink supply valve is opened, and printhead lock lever is opened) when ink fills the ink tube,
the ink in the ink tube may reverse-flow due to the difference in the water head, and ink may leak from the ink supply needle. Therefore, do not open all
of the ink passages at the same time when the ink tube is filled with ink.

2.3.2.2 Ink Tank Unit

2.3.2.2.1 Structure of ink tank unit

a) Ink tank
The ink tanks contain ink (approx. 130 ml) for each color.
The amount of ink is stored in the EEPROM mounted on the ink tank.
The remaining ink level in the ink tank is detected using a dot count based on the EEPROM information.
When the electrodes mounted to the hollow needle detect that there is no electrical current, a message appears on the display indicating that the ink is nearly
empty. If the dot count reaches the prescribed value from this state, the ink tank is considered to be empty.
b) Ink port
The hollow needle enters the ink port (covered by a rubber plug) when the ink tank lever of the printer is pressed down to the ink tank fixing position, and
this establishes an ink passage between the printer and ink tank.
c) Air passage
The open hollow needle enters the air passage (covered by a rubber plug) when the ink tank lever of the printer is pressed down to the ink tank fixing
position, and the internal pressure of the ink tank is opened so that the internal pressure is maintained at a fixed level.
d) Notches for preventing incorrect installation
The ink tanks have notches for preventing incorrect installation. The wrong ink tanks cannot be inserted and set because of these notches.
The ink tank lever can be lowered only when the ink tank has been installed in the set position, and the ink supply will not start unless the ink tank lever
is lowered.
2-10
Ink tank
Ink supply valve
Sub buffer
Mechanical Drive Unit
Ink or air flow
Carriage unit
Suction pump
Cap
Maintenance cartridge
F-2-8
Joint
Joint
Joint
0008-6341