Patent ID: 7692677

Claim:
A thermal printhead comprising: an insulating substrate; a glaze layer formed on the insulating substrate; a resistor layer formed on the glaze layer; an electrode formed on the resistor layer, part of the resistor layer being exposed to serve as a heating portion; and a protective layer covering the electrode and the heating portion; wherein the electrode is mainly composed of Al and comprises a lower first electrode layer and an upper second electrode layer covering part of the first electrode layer, the first electrode layer being spaced from the heating portion by a predetermined distance, the second electrode layer including an extension extending beyond the first electrode layer to adjoin the heating portion, the first electrode layer having a thickness in a range of 0.5 to 2.0 μm, the second electrode layer having a thickness in a range of 0.2 to 0.4 μm; wherein the glaze layer includes a bulging portion, the heating portion being positioned on the bulging portion; wherein the extension of the second electrode layer partially extends over the bulging portion, whereas the first electrode layer is spaced apart from the bulging portion; and wherein the first electrode layer includes a tapered end facing the bulging portion, the tapered end having a length in a range of 1 to 10 μm.