Thermal behavior of resistive ribbon for single-stylus excitation
by R. A. Laff, C. D. Makowka
This paper provides a quantitative description of the heating and cooling behavior of the resistive ribbon used in resistive ribbon thermal transfer printing. Since the focus is upon the ribbon, this description has been facilitated by substituting a single, tapered tungsten stylus as a model for a single printhead element. The experiment used an infrared spot pyrometer to measure ribbon surface temperatures downstream from the stylus while a laminate of ribbon and paper was continuously moved beneath the stylus and subjected to current pulses. Measured cooling rates under steady-state excitation at different ribbon velocities showed a behavior consistent with two simple analytic models which describe heat loss into the stylus during heating and two-dimensional diffusion into a half-plane during cooling. A detailed, time-dependent computer simulation using finite-element methods was used to provide a more detailed description of the process by taking into account the local geometry of the heat input distribution and the layered nature of the ribbon-paper laminate. The resulting three-dimensional temperature distributions are given for the steady-state case.