Abstract: A thermal head of this invention has an improved protective layer on the head surface. The protective layer comprises a compound containing Si, O, N, and a metal M (wherein M is at least one metal selected from the group consisting of Zr, Mg, and Y). The protective layer has high hardness and toughness and does not deform much nor crack if a local concentrated load acts on it during operation of the thermal head. In the thermal head of this invention, the protective layer and a high-resistance substrate comprises a material having high hardness such as a metal, an alloy, or a ceramic protect various interlayers formed therebetween. Even if a layer comprising a material having low hardness such as a heat insulating layer comprising a heat-resistant resin is included as an interlayer, deformation or a crack caused by a local stress acting on the thermal head can be prevented.

Abstract: In a thermal head, an electrical and heat insulating layer of glass is formed on a substrate made of ferrie Fe-Cr stainless steel. Fe-Cr stainless steel contains 16 to 18% chromium by weight. Heating resistors having a specific patterns are formed on the electrical and heat insulating layer and electrically connected to the substrate acting as a common electrode. Lead wires of an A.lambda.-Si-Cu alloy, as individual electrodes, are formed on the layer and the heating resistors. The heating resistors and the lead wires are covered by a protective layer.

Abstract: A thin resistor film type thermal head for printing on heat-sensitive paper, wherein a thin film of Ta--SiO.sub.2 containing 7 to 53 mol% of SiO.sub.2 or a thin film of Ta--SiO.sub.2 --N containing 7 to 53 mol% of SiO.sub.2, molar ratio of Ta to N being 1:0.5 to 1:1 is used as a heat-generating resistor.