Patent ID: 7185967

Claim:
A printing apparatus comprising: an ejection head moving in a first direction, said ejection head having a plurality of nozzles provided along a second direction which is different from said first direction, said plurality of nozzles selectively ejecting ink droplets of a plurality of sizes to form dots on a printing medium; and a controller for printing a first correction pattern and a second correction pattern, said first correction pattern and said second correction pattern enabling correction of a misalignment between a position at which dots are formed during a forward pass through which said head is moved and a position at which dots are formed during a return pass through which said head is moved, said first correction pattern and said second correction pattern are made of dots arranged in said first direction and said second direction, each dot that makes up said first correction pattern is a certain size, the size of each dot that makes up said second correction pattern is different from the size of said dots that make up said first correction pattern, a distance between the centers of neighboring dots arranged along said first direction of said first correction pattern and a distance between the centers of neighboring dots arranged along said first direction of said second correction pattern are limited to be the same distance, and a distance between the centers of neighboring dots arranged along said second direction of said first correction pattern is different from a distance between the centers of neighboring dots arranged along said second direction of said second correction pattern.