Thermal transfer printer with controlled ribbon feed

Claim 1

A thermal transfer printer providing controlled feed for a thermal transfer ribbon comprising a thermal printhead, advance means for advancing a print receiving medium past said thermal printhead, said thermal printhead having a plurality of heater elements disposed transverse to the direction of advancement of the medium, the thermal transfer ribbon being disposed between the print receiving medium and said thermal printhead; bias means maintaining the thermal transfer ribbon, the print receiving medium, and said thermal printhead in physical contact, select means for producing select signals for selecting heater elements to be energized, ribbon advance means for advancing the thermal transfer ribbon past said thermal printhead, and including means for determining the rate of advance of the thermal transfer ribbon relative to the rate of advance of the print receiving medium, and control means responsive to said select signals for controlling said ribbon advance means to vary the rate of advancement of the thermal transfer ribbon as a function of the number of heater elements selected, said control means including means for determining the number of heater elements selected by said select means by counting said select signals, and memory means having a plurality of addressable data storage locations with different data storage locations storing data representing different rates of advancement for the transfer ribbon as a function of the number of heater elements being energized, the count of the number of select signals produced being used to address said memory means to obtain the transfer ribbon advancement rate corresponding to the number of heater elements being energized.