Patent ID: 8411308

Claim:
A printing machine comprising: a transfer belt of an endless form applied over support rollers, driving means for rotating the support rollers to move the transfer belt in an endless manner, and ink heads for forming images to overlap on a record sheet on the transfer belt, the printing machine further comprising: speed measuring means for measuring travel speeds at a pair of measurement points set on a combination of the transfer belt and the support rollers; an extractor for working with a temporal variation in ratios of speeds between the measurement points measured by the speed measuring means to extract a set of speed ratio data having frequencies corresponding to the ratios of the speeds; a storage for storing the set of speed ratio data as extracted; print control means for working with the set of speed ratio data stored in the storage to control timings of formation of images by the ink heads for reduction in positional deviation among the images on the transfer belt; and the ink heads for working with the print control means to form images on a record medium.