| 摘要 |
A fluorescent display tube power supply device of a microwave oven provides a stable power source for the microcomputer by rectifying the output of the first secondary coil of the commercial AC power transformer, followed by rectifying a half wave of the second secondary coil of the same AC power transformer before feeding one-half cycle of the commercial AC current to the heater of the fluorescent display tube. The power supply uses a rectifying circuit for generating the double voltage for the second secondary coil, the double voltage being mixed in the direction in which it becomes lower than the stable voltage of the microcomputer, thus generating the display erase potential VP. As a result, luminance can be held constant respective display positions without causing the voltage of the display tube to vary throughout the ON-OFF operations of the heating power source, thus eventually achieving a highly satisfactory display effect. |
