摘要 |
A ceramic heater including a ceramic insulator having a circular cross section, and a heating coil having an oval cross section, embedded in the insulator along the length thereof, and bent in a U-shaped form with the bend adjacent one end of the insulator. One of a pair of parallel coil portions defining the U-shaped coil has a long cross sectional diameter lying parallel to that of the other coil portion. The diameter of a cylinder defined by the outer surfaces of the coil portions and the outside diameter of the insulator have a ratio of 35:100 to 70:100. |