Patent ID: 9302471
Filing Date: 2016-04-05
CPC Classification: B41J

Claim Text:
1. A liquid droplet discharging method, comprising: providing a printer with a transport action where a print medium is moved in a transporting direction, and with a liquid droplet discharging scan action where a first print head and a second print head move and discharge liquid droplets onto the print medium in a scanning direction intersecting the transporting direction, said first print head having a first column of liquid-discharging nozzles lined up in the transporting direction, said second print head having a second column of liquid-discharging nozzles lined up in the transporting direction, said first print head and second print head being offset from each other in the scanning direction; wherein: said print medium has an upper-end portion wherein only the first print head discharges liquid onto the print medium, a central portion wherein both the first print head and second print head discharge liquid onto the print medium, and a lower-end portion wherein only the second print head discharges liquid onto the print medium; said printer further having access to a first correction quantity table providing color correction based on liquid discharged only by the first print head, a second correction quantity table providing color correction based on an liquid discharge combination of both the first print head and second print head at a predetermined liquid discharge ratio Hk of the first print head to the second print head, and a third correction quantity table providing color correction based on liquid discharged only by the second print head; the transport action and the liquid droplet discharging scan action are alternately repeated so as to cause a plurality of dot rows to be formed in the scanning direction during each liquid droplet discharge scan action, and for the print media to be advanced in the transporting direction a predefined number of dot rows during each transport action; the method further comprising: using the first correction quantity table, the second correction quantity table, the third correction quantity table, and a relative usage ratio defined as a ratio of expected liquid discharge of the first print head to expected liquid discharge of the second print head for a given liquid droplet discharging scan action to correct a liquid droplet quantity discharged from at least one of the first column of liquid-discharging nozzles and the second column of liquid-discharging nozzles in the given liquid droplet discharging scan action.