Patent ID: 9704076
Date: 2017-07-11
CPC Classifications: B41J,B65H,G01D,G06K

Claim:
1. A rotary encoder correcting method for a transport apparatus having a transport roller disposed on a transport path for transporting a printing medium and rotatable synchronously with transportation of the printing medium, and a rotary encoder with a shaft thereof connected to the transport roller for outputting output signals in response to rotation of the transport roller, the method comprising the steps of: setting beforehand the number of n-divided output signals obtained by dividing, by n (n being an integer 2 or more), the number of output signals outputted from the rotary encoder with one rotation of the transport roller; measuring a time taken to output the number of n-divided output signals as a divided area shift time for each divided area when the printing medium is transported at constant speed and each time the number of output signals of the rotary encoder agrees with the number of n-divided output signals; and calculating a correction coefficient for each divided area based on the divided area shift time; wherein the divided area shift time is corrected for each divided area of the rotary encoder based on each correction coefficient when the printing medium is transported along the transport path and a process is carried out on the printing medium.