Patent ID: 7178895

Claim:
A correcting method of a difference between dot formation positions in a reciprocal operation of a liquid ejecting head, comprising the steps of: reciprocating the liquid ejecting head along a liquid ejecting path in a first direction and a second direction, which is an inverse direction of the first direction, the liquid ejecting head having a plurality of nozzles for ejecting liquid droplets; ejecting liquid droplets while moving the liquid ejection head in the first direction, thereby forming first patterns; ejecting liquid droplets while moving the liquid ejection head in the second direction, thereby forming second patterns, wherein each of the second patterns is adjacent to one of the first patterns so that the second patterns form pairs with the first patterns; and ejecting liquid droplets while moving the liquid ejection head in the second direction, thereby forming third patterns, wherein each of the third patterns is adjacent to one of the first patterns so that the third patterns pair with the first patterns; wherein each of the first and the second patterns comprises a plurality of dots arranged in the first direction and in a third direction perpendicular to the first direction, thereby forming a block; wherein widths of at least one of the first patterns and the second patterns vary along the first direction so that each pair of a first pattern and a second pattern has a different correction amount; wherein each pair of a first pattern and a third pattern has a different correction amount; wherein the second patterns and the third patterns are formed using different nozzle rows of the liquid ejecting head; wherein a correction amount of a first nozzle row is determined based on the pairs of the first patterns and the second patterns; and wherein a correction amount of a second nozzle row is determined based on the pairs of the first patterns and the third patterns.