Patent ID: 8168926

Claim:
A heating device, comprising: a base having a heating surface, which is made of ceramics; and a first heating element and a second heating element, which are embedded in the base, and are capable of individually controlling temperatures thereof, wherein each of the first heating element and the second heating element is formed into a spiral shape so as not to contact the other from a central portion of the base to an outer circumferential portion of the base in substantially a same plane parallel to the heating surface of the base, and one of the first heating element and the second heating element includes a high heating density portion on the central portion side of the base, and a low heating density portion on the peripheral portion side of the base, and the other of the first heating element and the second heating element includes a low heating density portion on the central portion side of the base, and a high heating density portion on the peripheral portion side of the base.