| 摘要 |
PURPOSE:To increase the upper limit of the resistance value of a temperature detection electrode line and increase the level of malfunction due to noises by accumulating a charge which flows from a DC voltage generated by a control power source circuit through the temperature electrode line and discharging an erroneous charge repeatedly through a disconnection detecting circuit. CONSTITUTION:An electric power control element 6 is connected between an AC power source VAC and a heating body 5 to control the feeding to the heating body 5. A temperature sensing element 9 is interposed between the heating body 5 and temperature detection electrode line 8, and the element 9 and a temperature detecting circuit 10 detect the temperature of the heating body 5. The charge flowing from the DC voltage generated by the detecting circuit 10 through the electrode line 8 is accumulated and discharged periodically by the disconnection detecting circuit 15 to detect the breaking of the electrode line 8. The output of this detecting circuit 15 is inputted to a pulse generation part 33, whose output pulse triggers the element 6. Then, the upper limit of the resistance value of the electrode line 8 is increased, and malfunction of the control power source circuit 38 due to noises is prevented. |
