Print head alignment method, test pattern used in the method, and a system thereof

A method of aligning one or more print heads in a print head unit, the method comprising:

• printing a first pattern of first symbols on a first region of a print medium and printing a second pattern of second symbols on the first region of the print medium with one or more print heads in a manner to superpose the second pattern on the first pattern;
• offsetting at least one of the second symbols from corresponding first symbol in both a first offset direction and a second offset direction;
• recording a first offset distance for the first offset direction and a second offset distance for the second offset direction of each offset second symbol;
• designating at least one of the second symbols that is most completely obscured by a corresponding one of the first symbols;
• and
• using a first offset distance and a second offset distance corresponding to the designated second symbol as offset parameters for aligning one of the one or more print heads.