US Patent 11148424 Printing apparatus and ink replenishment method

A printing apparatus comprises a main tank, an intermediate tank, and a control unit controlling an amount of the ink stored in the intermediate tank by a normal replenishing operation for increasing an ink remaining amount to a normal amount more than a first reference amount by feeding the ink from the main tank to the intermediate tank if the ink remaining amount falls below the first reference amount. The control unit controls the amount of the ink stored in the intermediate tank by an extraordinary replenishing operation for increasing the ink remaining amount to a second reference amount by feeding the ink from the main tank to the intermediate tank if the ink remaining amount falls below the second reference amount less than the first reference amount when the main tank held is exchanged.