US Patent 7413282 Ink jet printing apparatus and preliminary ejecting method

In both a full-line and a serial printer, the amount of ink passing through nozzles of print heads is sometimes decreased below a normal value before and during actual printing. In the printer of the present invention, a preliminary ejecting operation is performed taking the opportunity in which the amount of ink passing through nozzles is decreased below a normal value. Then, the amount of ink passing through nozzles recovers to the normal value in ink ejection after the preliminary ejecting operation. Since only a small amount of ink is ejected through the nozzles during the preliminary ejection operation, dots formed on a print sheet are not noticeable. Further, it is unnecessary to move the print heads to a home position where an ejection recovering process is executed to remove ink having an increased viscosity.