| 摘要 |
PROBLEM TO BE SOLVED: To provide an ignition element with a simple structure capable of easily detecting ignition. SOLUTION: A plurality of heating layers 12 are embedded within an insulating material 11 while first and second temperature measuring layers 13, 14 are embedded therewithin for measuring the temperatures of two different positions. Temperature measuring parts 13a, 14a of the layers 13, 14 are symmetrically provided in positions having substantially equal temperatures in an area where temperature distribution formed by the heating of the layers 12 is substantially symmetrical with respect to a middle part of a heating part 13a. Although the heating of the layers 12 increases the temperatures of the measuring parts 13a, 14a, the temperature difference between them remains smaller than a reference value. When one of them is heated more than the other by ignition, the temperature difference exceeds the reference value. By this temperature difference, the ignition can be easily detected.
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