Abstract: An inkjet printing apparatus includes: a positional displacement amount calculation unit configured to, during printing processing, calculate a positional displacement amount of printing paper in a paper width direction based on colorimetric data obtained by colorimetry of a color chart by a colorimeter; a colorimeter movement mechanism configured to move the colorimeter; and a colorimeter movement control unit configured to control an operation of the colorimeter movement mechanism based on the positional displacement amount calculated by the positional displacement amount calculation unit.

Abstract: In a printing device, a measurement position detection chart including a reference pattern and a detection pattern is printed on printing paper. A colorimeter performs color measurements on the chart. The reference pattern has a sufficient dimension in a paper width direction to cover the range of a color chart in the same direction. The detection pattern includes multiple rectangular patches arranged in a conveyance direction while deviating from one another in the paper width direction. The color measurements result in colorimetric data, containing detection pattern density values Dp1 to Dpn, which is used to identify, as a current measurement position qc, a position of a patch in the paper width direction corresponding to a density value Dpk generally equal to a reference density value Drf among the detection pattern density values Dp1 to Dpn.

Abstract: A sub-tank is pressurized by a pump, with head valves closed. Then, one of the head valves is opened to perform a first purge on a first head. After the one head valve is closed, a different one of the head valves is opened to perform a second purge on a second head different from the first head. After these purges, an open-to-atmosphere valve is opened, with the head valves closed, to decrease the pressures inside the heads which are increased by the purges. This allows a selective purge on only a head which requires a purge. As a result, the amount of ink forced out is suppressed during the pressurized purges. After the sub-tank is made open to the atmosphere, a depressurizing pump depressurizes the sub-tank to form ink menisci in the heads. This prevents air bubbles from being drawn into nozzles during the formation of the ink menisci in the nozzles after the purges.

Abstract: A sub-tank is pressurized by a pump, with head valves closed. Then, one of the head valves is opened to perform a first purge on a first head. After the one head valve is closed, a different one of the head valves is opened to perform a second purge on a second head different from the first head. After these purges, an open-to-atmosphere valve is opened, with the head valves closed, to decrease the pressures inside the heads which are increased by the purges. This allows a selective purge on only a head which requires a purge. As a result, the amount of ink forced out is suppressed during the pressurized purges. After the sub-tank is made open to the atmosphere, a depressurizing pump depressurizes the sub-tank to form ink menisci in the heads. This prevents air bubbles from being drawn into nozzles during the formation of the ink menisci in the nozzles after the purges.