Canon iPF720 - imagePROGRAF Color Inkjet Printer, Service Manual

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Chapter 2
2-22
2.3.2.5 Purge Unit
2.3.2.5.1 Functions of Purge Unit
0013-8022
To maintain high print quality, the purge unit performs maintenance of the nozzles o the printhead.
The purge unit supports a capping function, cleaning function, and ink supply function.
a) Capping function
The capping function presses the cap of the purge unit against the face plate on the nozzle section of the printhead to prevent nozzle drying and dust adhesion.
Capping is performed when printing is complete, at the start of the suction operation, and when switching to the standby state due to an error.
The capping function also establishes the ink passage between the printhead and purge unit.
b) Cleaning function
The cleaning function restores the printhead to the state where ink can be easily discharged from nozzles. This function includes the following three types of oper-
ations.
- Wiping operation
This operation is performed to remove paper fibers and dried ink from to the face plate.
- Pumping operation
This operation is performed to remove ink from the nozzles and fill the nozzles with fresh ink.
- Maintenance jet operation
This operation is performed to spray ink from the nozzles to the cap, borderless ink jet tray, an paper to remove bubbles in the nozzles and dust and other foreign
particles.
c) Ink supply function
The suction pump of the purge unit operates together with the ink supply valve to supply ink to the printhead during the initial filling and ink level adjustment.