Printing apparatus for web

A printing apparatus comprising:

• a first printer including first print mechanisms aligned in a conveyance direction of a web, the first printer being configured to print a first image on a first surface of the web being conveyed by using the first print mechanisms;
• a second printer including second print mechanisms aligned in the conveyance direction the second printer being configured to print a second image on at second surface of the web being conveyed by using the second print mechanisms;
• a first roller configured to rotate in synchronization with the web being conveyed;
• a second roller configured to rotate in synchronization with the web being conveyed;
• a first encoder configured to output a first pulse signal depending on a rotation angle of the first roller;
• a second encoder configured to output a second pulse signal depending on a rotation angle of the second roller;
• and
• a controller configured to
• receive the first pulse signal outputted from the first encoder and the second pulse signal outputted from the second encoder,
• generate a first corrected pulse signal by correcting the received first pulse signal or generate a second corrected pulse signal by correcting the received second pulse signal, based on a difference value between a first rotation cycle of the first roller and a second rotation cycle of the second roller such that a difference between a first pulse cycle of the received first pulse signal and a second pulse cycle of the received second pulse signal is reduced,
• upon generating the first corrected pulse signal, control first print timings in the respective first print mechanisms of the first printer based on the generated first corrected pulse signal, and
• upon generating the second corrected pulse signal, control second print timings in the respective second print mechanisms of the second printer based on the generated second corrected pulse signal.