Patent ID: 7021731

Claim:
An ink-jet printing apparatus, comprising: a main tank storing ink; a sub-tank separable and connectable with said main tank through an ink supply passage; a printing head for ejecting ink supplied from said sub-tank; printing means for performing printing by ejecting ink from said printing head to a printing medium, while said sub-tank and said printing head are scanning across the printing medium, said sub-tank being separated from said main tank during the scanning; ink draining means for performing an ink draining process for draining at least a part of ink remaining in said sub-tank within a period after completion of printing at a preceding time and before starting printing at a next time; and ink supply means for supplying ink from said main tank to said sub-tank through the ink supply passage within the period and after completion of the ink draining process, wherein said ink supply means supplies to said sub-tank the same type of ink as the ink drained by said ink draining means.