Printer feedback control and event library to compensate for and predict

Abstract

An apparatus for use in a thermal printer for printing information onto a paper substrate material is provided. The apparatus enables the thermal printer to compensate for the variable payout force of the paper substrate material. The apparatus comprises a platen in contact with the paper substrate material at a print region of the thermal printer. A motor and a roller mechanically coupled to the motor are used to transport the paper substrate material through the print region. A rotational rate detector comprises a light source, a disk having alternating radially disposed regions of different light conductivity, and a photodetector adjacent to the disk. The disk is at least partially illuminated by light provided by the light source and the photodetector to provide an electrical signal corresponding to detected periodic changes of the light illuminated onto the disk during rotation of the disk in cooperation with the platen. A central processor is adapted to receive the electrical signal and provide a driving signal to the motor. The driving signal compensates for the variable payout force by altering a corresponding transport rate of the paper substrate material in accordance with the detected rotational rate of the disk, an event model stored in a RAM, and/or a harmonic model stored in the RAM.