Thin film thermal print head

Abstract

The thermal print head disclosed herein comprises resistive heating elements deposited on mesas of glass glaze over an aluminum oxide substrate for more efficient marking of thermally sensitive recording material. After the mesas are formed in the glass glaze by etching, resistive and conductive materials are deposited over the mesas by thin film techniques. Thereafter, the raised heater elements and conductors are delineated chemically, then heat-treated to upwardly adjust the resistance of and to grow a protective oxide over the individual heater elements. Since the resistance value of the heater elements can be controllably increased as a function of the temperature and time of heat treatment, external trimming resistors are eliminated. The protective oxide which forms over the resistors during heat treatment provides better adhesion to wear-resistant materials and an effective barrier to migration of ions from the recording material into the heater elements causing degration of performance and shortened element life.

Dependencies are inferred from the claim text.