Thermal printhead and thermal printer

A thermal printhead, comprising:

• a substrate having a main surface and protrusions protruding from the main surface and extending in a main scanning direction;
• a resistor layer including a plurality of heat generation portions arranged on the protrusions of the substrate in the main scanning direction and configured to generate heat when supplied with an electric current;
• and
• a driver circuit configured to apply the electric current to the plurality of heat generation portions based on an external signal,
• wherein each of the protrusions includes a flat portion substantially parallel to the main surface, a first inclined portion configured to be connected to a first end of the flat portion in a sub-scanning direction and inclined toward an end portion of the substrate, a second inclined portion configured to connect the first inclined portion to the main surface at a larger angle than the first inclined portion with respect to the main surface, a third inclined portion configured to be connected to a second end of the flat portion in the sub-scanning direction and inclined to face the first inclined portion, and a fourth inclined portion configured to connect the third inclined portion to the main surface at a larger angle than the third inclined portion with respect to the main surface,
• wherein the plurality of heat generation portions are provided over a range from the first inclined portion to the flat portion, and
• wherein a dimension of the flat portion in the sub-scanning direction is 100 μm to 500 μm.