Patent ID: 8465146

Claim:
A roll paper conveying apparatus comprising: a carriage roller that is driven by a conveying motor, and intermittently conveys roll paper by an amount of paper to be fed corresponding to a predetermined print width to a predetermined printing position; a paper feeding roller that is driven by a feed motor, unwinds the roll paper, and pulls and conveys the roll paper toward the carriage roller intermittently; a first detecting unit that detects a rotation angle of the paper feeding roller; a feed motor control unit that performs feedback control of the feed motor using a detection value of the first detecting unit so that a conveying speed and a conveying position of the roll paper follow target values; a movable member that is kept in contact with the roll paper at a position between the paper feeding roller and the carriage roller, and is displaced from a reference position to absorb a change in a tensile force of the roll paper caused by a difference between rotation speeds of the paper feeding roller and the carriage roller; a second detecting unit that detects a position of the movable member; and a correcting unit that calculates a correction value corresponding to an amount of displacement of the movable member from the reference position and an integration of the amount of displacement based on a detection value of the second detecting unit and corrects an output of the feed motor control unit using the correction value thus calculated.