Patent ID: 7850273

Claim:
A printing apparatus comprising: a roller for conveying a printing medium; a controller for forming a test pattern used to detect a conveying error of the roller on the printing medium; a first-correction-value acquisition unit for acquiring, by use of the test pattern, a first correction value used to correct a conveying error that depends on the eccentricity of the roller; and a second-correction-value acquisition unit for acquiring, by use of the test pattern and the first correction value, a second correction value used to correct a conveying error that depends on the outer diameter of the roller, wherein the first correction value used to correct the conveying error that depends on the eccentricity of the roller is a correction value associated with the rotational angle from a reference position of the roller, and wherein the first-correction-value acquisition unit acquires the first correction value on the basis of a periodic function with the opposite polarity to the conveying error that appears periodically with a period equal to the circumferential length of the roller.