Patent ID: 11924929
Assignee: NGK INSULATORS, LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A ceramic heater comprising:
a ceramic plate having a disk shape and having a wafer placement surface;
a tubular shaft having one end that is bonded to a rear surface of the ceramic plate on an opposite side to the wafer placement surface;
an inner-peripheral-side resistance heating element that is embedded in an inner peripheral portion of the ceramic plate;
an outer-peripheral-side resistance heating element that is embedded in an outer peripheral portion of the ceramic plate;
a within-shaft region of the rear surface of the ceramic plate, the within-shaft region locating within the tubular shaft;
an elongate hole that extends from a start point in an outer peripheral portion of the within-shaft region to a predetermined terminal end position in the outer peripheral portion of the ceramic plate;
associated parts that are disposed in the within-shaft region and that include a pair of terminals of the inner-peripheral-side resistance heating element and a pair of terminals of the outer-peripheral-side resistance heating element; and
a thermocouple guide that guides a tip end of a thermocouple to come into the start point of the elongate hole,
wherein a portion of the thermocouple guide, the portion extending from the other end of the tubular shaft to the start point of the elongate hole, is formed in a shape following an inner wall of the tubular shaft; and
wherein the thermocouple guide is curved toward the start point of the elongate hole in a shape defining part of a spiral along the inner wall of the tubular shaft just before the start point of the elongate hole; and
wherein the part of the spiral is one quarter to one half circle in the circumferential direction.