Serial printing device having data discrimination

A serial printing device comprising:

• a first serial printing head including a plural number of dot forming element series each comprising a plural number of dot forming elements linearly arrayed at fixed pitches in a printing medium feeding direction, said plural number of dot forming element series being arrayed in a printing medium width direction and being shifted from each other in the printing medium feeding direction;
• a second serial printing head including a plural number of dot forming element series, said plural number of dot forming element series being arrayed side by side in the printing medium width direction and aligned in the printing medium width direction with the dot forming elements of one of said plural number of dot forming element series of said first serial printing head, colors of dots formed by the dot forming elements of said second serial printing head being different from a color of dots formed by the dot forming elements of said first serial printing head;
• a carriage on which said first and second serial printing heads are mounted, said carriage being reciprocally movable in the printing medium width direction;
• control means for controlling a first printing process wherein, when a moving speed of said carriage reaches a constant speed for printing, print data is outputted to said first serial printing head for printing an image of one line by one printing path, and for controlling a second printing process wherein the print data is outputted to said second serial printing head, and an image is printed in a plural number of printing paths by feeding the printing medium in the printing medium feeding direction in increments less than one line as each of said plural number of printing paths is completed;
• and
• data discriminating means for discriminating the first or the second printing process, based on the print data, and for selecting the discriminated printing process.