| 摘要 |
PURPOSE:For preventing such operator's accident as burn, to inhibit the temperature rise of an induction heating cooker having a soft start circuit when heating is made by applying small load. CONSTITUTION:When heating start signal is supplied to a switch 1, the NPN transistor 49 for prohibiting the operation of a voltage control oscillator (VCO) 40 is turned on and a power convertor 10 is driven. The output of heating start signal delays the switch-off of an output transistor 56 by means of a delay circuit 4 while the transistor 57 of a low-outout setting device 5 limits the connection point of resistors 34 and 35 to the base potential determined by resistors 59 and 60 and a diode 61. Therefore, a variable resistor 36 is not used when the reference voltage of an error amplifier 9 is determined. The output signal of said amplifier 9 supplies reference signal to the amplifier 66 of a small load detector 6, and heating start signal is prohibited by a transistor 72 during a fixed space of time. |
