| 摘要 |
PROBLEM TO BE SOLVED: To detect the disconnection of a potential conductor for impressing negative potential by forming the potential conductor to a cord heater type by covering the armor of the potential conductor with an insulating layer and imparting pulse components thereto by switching the negative potential outputted from a potential output means. SOLUTION: A power source plug 14 is connected to a power source and the voltage of the power source is boosted by the double voltage current rectification of a potential generating circuit 15. The negative potential is then outputted to a thermosensitive exothermic wire 37 formed to the cord-like heater by covering the armor of the potential conductor 11 with the insulating layer. In addition, a triac 16 is connected in series to the potential generating circuit 15 and a microcomputer 17 is connected in series thereto. The pulse components are turned on and off and are added by the drive signal from the microcomputer 17. As a result, when the potential conductor 11 is disconnected, the pulse components are no longer outputted from a disconnection detecting circuit 29 and, therefore, the microcomputer 17 judges the disconnection state and is capable of stopping all the operations including the heating function.
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