Patent ID: 11939179

Abstract:
The measured winding diameter values Ds1(d) corresponding to the conveying distance d are measured by measuring the diameter of the printing medium M wound on the unwinding roll 71 by the diameter sensor 77. The measured winding diameter values Ds1(d) are smoothed by the low-pass filter to extract the smoothed winding diameter values Ds_avg1(d). By calculating the value of the diameter based on the initial diameter value Do1, the thickness value Tm and the conveying distance of the printing medium M, the calculated winding diameter values Dc1(d) are calculated. An operation of calculating the difference Ddiff1(d) between the calculated winding diameter value Dc1(d) and the smoothed winding diameter value Ds_avg1(d) while compensating for the delay by the low-pass filter is performed whereby the differences Ddiff1(d) are calculated. The calculated winding diameter value Dc1(d) are corrected by the differences Ddiff1(d).