| 摘要 |
PURPOSE:To prevent the abnormal overheating of a heater member, by a method wherein an ignition heater of a large electric energy, coping with the heat capacity of the load of a heat generating resistance body, is employed to heat rapidly while the electric energy is reduced after the temperature of the heater member has arrived at a necessary temperature. CONSTITUTION:When a heater control signal 7 is impressed and conduction is promoted, a switching means 3 closes a circuit under the condition of continuous conduction in accordance with the output signal of a temperature detecting means 4, and is triggered through a zero closs detecting means 6, whereby an ignition heater 1 is heated rapidly by the continuous conduction. When the electric resistance of the heater member of the ignition heater 1 increases to exceed a safe use upper limit temperature and the balance of a resistor bridge 2 reverses, the output signal of the temperature detecting means 4 also reverses and the trigger signal of the switching means 3 is only an intermittent conduction pulse signal produced by a trigger signal generating means 5, whereby the conduction of the ignition heater 1 is switched to intermittent conduction. A pulse width and a repeating period are set so that the intermittent conduction pulse signal brings a conduction condition, in which the temperature of the heater member does not exceed the safe use upper limit temperature; therefore, unnecessary overheating of the ignition heater 1 may be prevented after the conduction is switched to the intermittent conduction.
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