Abstract: The present invention includes a head holder configured to collectively holding a plurality of discharge heads and a collective head mover configured to move the head holder between a printing space above the printing medium being conveyed in the conveying direction and a retraction space separated from the printing space. Therefore, is provided a printing technique capable of printing a high-quality image at low cost by discharging inks from a plurality of discharge heads arranged adjacent to each other in a direction parallel to a conveying direction of a printing medium while reciprocally moving the respective discharge heads between a printing space and a retraction space.

Abstract: Closing the replenishing solenoid valve V11 and opening the return solenoid valve V12 prohibits passage of the ink fed using the replenishing pump 951 through the replenishing solenoid valve V11 and allows this ink to pass through the return solenoid valve V12. In this way, the ink is circulated along the circulation path Cc2 (second circulation path) along which the ink is fed from the buffer tank 95a to the branch point J though the replenishing pipe 95b and then fed from the branch point J to the buffer tank 95a through the return pipe 961.

Abstract: The cleaning liquid is supplied to the head facing flat surface, and the dummy flat surface of the dummy block facing the head facing flat surface contacts the cleaning liquid. This causes the cleaning liquid to be spread on the head facing flat surface by the dummy flat surface. The cleaning liquid spread on the head facing flat surface is sucked through the suction holes of the suction block. The suction holes can be cleaned by the cleaning liquid passing through the suction holes according to suction. On this occasion, the ink supplied to the head facing flat surface is removed through the suction holes of the suction block. The suction holes have both a function of removing the ink from the discharge heads H and a function of removing the cleaning liquid from the head facing flat surface.

Abstract: The ratio of the rotation speed Nr of the take-up roller (take-up rotation speed) and the rotation speed Nu of the feeding roller (feeding rotation speed) is used. That is, knowledge that the roll diameter Drr of the sheet S taken up on the take-up roller is given by a function using the ratio of the rotation speeds Nr and Nu as a variable was obtained. Accordingly, the roll diameter Drr is computed from this ratio.

Abstract: A printing apparatus, comprises: a discharge head; a recovery tank that stores ink recovered from the discharge head; a supply tank that stores ink to be supplied to the discharge head; a circulation pump that performs an ink circulation operation of circulating ink in a circulation path that returns to the recovery tank after reaching the discharge head from the recovery tank via the supply tank; a first negative pressure applying part configured to apply a negative pressure to the supply tank; a second negative pressure applying part configured to apply a negative pressure to the recovery tank; a first solenoid valve to cut off the supply tank and the recovery tank when being energized and cause the supply tank and the recovery tank to communicate when not being energized; and a power supply part configured to supply electric power to the circulation pump and the first solenoid valve.