US Patent 7173219 Ceramic heaters

An object of the present invention is to provide a heater having a ceramic substrate with a through hole formed therein so that the uniformity of temperature on the heating face of the substrate can be improved and the use life of the ceramic substrate can be improved upon thermal cycles. A ceramic heater comprises a substrate made of a ceramic material and having a heating face where three or more zones 3C, 3F are allocated, heating resistances corresponding to the zones, respectively, and terminals 5C electrically connected to the heating resistances, respectively. Three or more holes 4 are formed in the substrate. Distances of the terminals 5C and the wall surfaces facing the holes 4 are 8 mm or more, respectively. The heating resistance 15 intersects a straight line 16 connecting the center of the terminal and the center 4a of the hole in a plan view.