Ink jet printing apparatus and method

An ink jet printing apparatus comprising:

• a conveyance system for conveying a print medium along a first direction;
• a first printing head in which a plurality of printing elements are arranged in a second direction different from the first direction;
• a second printing head in which a plurality of printing elements are arranged in the second direction, and provided at a downstream side with respect to the first printing head in the first direction;
• a third printing head in which a plurality of printing elements are arranged in the second direction, and provided at a downstream side with respect to the second printing head in the first direction;
• a first Doppler speedometer that acquires a moving speed of the print medium in a vicinity of the first printing head;
• a second Doppler speedometer that acquires a moving speed of the print medium in a vicinity of the second printing head;
• a third Doppler speedometer that acquires a moving speed of the print medium in a vicinity of the third printing head;
• and
• a control unit that controls driving timings of the first, the second, and the third printing heads, wherein the driving timing of the second printing head is adjusted based on a first signal generated by a difference in the moving speeds acquired by the first and the second Doppler speedometers, and the driving timing of the third printing head is adjusted based on a second signal generated by a difference in the moving speeds acquired by the second and the third Doppler speedometers, as well as the first signal.