Patent ID: 8294069

Claim:
A heating device made of ceramics, comprising: a plate-like heating base having a heating surface; a hollow cylindrical support member bonded to a back surface of the heating base so that an axis direction thereof is perpendicular to the back surface; and a concave surface portion connecting the back surface of the heating base and an outer surface of the support member smoothly to each other, said concave surface portion being formed at a location that includes a bonded portion between the heating base and the support member, wherein on a cross section including an axis of the support member, the concave surface portion has a curved line of an arc of an ellipsoid having a minor axis and a major axis, wherein the minor axis direction is parallel to the axis direction of the support member, and in the concave surface portion, a ratio B/A of the radius, B, of the major axis of the ellipsoid with respect to the radius, A, of the minor axis of the ellipsoid is 1.5 to 5.0.