US Patent 8007070 Ink-jet printer and maintenance method for ink-jet printer

Ink consumption amount is calculated based on an ink amount which is used for recording and periodic preparatory jetting in a predetermined time period after a previous discharge operation. An ink of an ink amount obtained by subtracting a consumption amount for the predetermined time, from an ink capacity of an ink supply system which supplies the ink from an ink cartridge to a recording head, is discharged by a discharge mechanism. Accordingly, it is possible to maintain a favorable state of ink by replacing periodically the ink in the ink supply system without a wasteful consumption. Moreover, when the amount of ink consumed in the predetermined time period is same as or more than the ink capacity of the ink supply system, the discharge operation is not carried out. Therefore, it is possible to suppress the consumption of ink due to the discharge operation.