Ink jet printing method printing a test substrate and a printing target

An ink-jet printing method, comprising:

• (i) measuring a first distance between a printing target and at least one nozzle and measuring a second distance between a test substrate and the at least one nozzle;
• (ii) measuring a flying speed and a flying angle of an ink discharged from the at least one nozzle;
• (iii) printing an ink spot on the test substrate with the ink from the at least one nozzle to identify a location on which the ink spot is printed on the test substrate, and determining a thickness-related displacement of an ink spot to be printed on the printing target from the location of the ink spot printed on the test substrate, based on
• a thickness difference between the thickness of the test substrate and the thickness of the printing target, determined by a distance difference between the first distance and the second distance, and
• the flying speed and the flying angle of the ink measured in Step (ii);
• and
• (iv) discharging ink from the at least one nozzle to print the ink spot to be printed on the printing target on the printing target with the ink while correcting the thickness-related displacement of the ink spot to be printed on the printing target from the location on which the ink spot printed on the test substrate is printed on the test substrate.