Resistance-stable thermal print heads

摘要

A thermal print head which includes an array of individually addressable resistors on a substrate is provided to substantially reduce undesirable drift in the resistance values of the resistors. The thermal print head includes a thermally stable glaze having a smooth surface formed on the substrate, and an electrically resistive doped-semiconductive layer formed on the smooth glaze surface. An array of first and second electrode pairs is formed on the resistive layer such that each of the electrodes forms a gap therebetween. A protective layer is formed over the electrode pairs and over the resistive layer at the gap. An electrically conductive layer is formed on the protective layer. The thermal print head includes a structure for applying first and second potentials respectively to the first and second electrodes of each of the pairs for selectably heating each of the resistors, and applying a third potential to the conductive layer. The thermal print head further includes a structure for switching the potential of the first electrode from a low terminal potential state to a state substantially equal to the potential of the second electrode, and for providing the absolute value of the potential of the third electrode to be greater than the low terminal potential.