Patent ID: 8071920

Claim:
A planar heater in which a carbon wire heat generator is planarly arranged and sealed in the internal portion of a silica glass plate-like member and a power supply terminal unit which supplies an electric power to the carbon wire heat generator is arranged at a central portion on a lower surface of the silica glass plate-like member, wherein the power supply terminal unit comprises a connection line which supplies an electric power to the carbon wire heat generator; a small-diameter silica glass tube which contains the connection line; and a large-diameter silica glass tube which contains the small-diameter silica glass tube and is attached to have an upper end portion being in contact with the lower surface of the heater, a flange portion is formed on a lower end portion of the large-diameter silica glass tube, and a bent portion having different diameters is formed between the upper end portion and the flange portion, and a first heat shielding plate configured by any one of a metal plate, or an opaque silica glass plate, or a combination therebetween is contained in the large-diameter silica glass tube below the bent portion.