| 摘要 |
PROBLEM TO BE SOLVED: To provide a control method of a ceramic heater generating heat by the power supplied from a power source, which can prevent the breaking and cracking of heaters and control the quantity of heat at low cost. SOLUTION: At a heater control device, the example of implementation of which is shown in Figure (b), when an FET 17 comes to on-state, voltage of a power source 11 is applied to both ends of the serial circuit consisted of the first heater 13, the second heater 15 and the resistor 27 for voltage drop, and the conducting period to the heaters is controlled by a DUTY control. Thus, the effective value the applied voltage can be restrained below the allowable voltage, and the flow of big electric current to the heaters is prevented. Accordingly, the cracking at the heaters caused by sudden change of temperature and breakage of heaters caused by migration are prevented, and heaters are controlled by using the FET of low-cost.
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