Patent ID: 9744774
Date: 2017-08-29
CPC Classifications: B41J

Claim:
1. A thermal print head, comprising: a main substrate with a main surface; a plurality of heating elements supported by the main surface and arranged along a main scanning direction; a protection layer covering the plurality of heating elements; a belt-shaped heating glaze layer between the main surface of the main substrate and the plurality of heating elements, and extending along the main scanning direction and bulging towards the direction where the main surface faces, as viewed from the main substrate thickness direction; wherein the protection layer has a surface shaped with an equivalent radius of curvature between 6200 μm and 15000 μm, the equivalent radius of curvature is calculated by, along a thickness direction, a height which is ¼ of a maximum height of a bulging portion of the protection layer including the heating glaze layer, and a width of the bulging portion along a sub-scanning direction measured at a location that is ¼ of the maximum height of the bulging portion from the surface of the maximally-bulging portion.