Fish & Richardson
Microwave oven having a fan motor rotation control function
 A microwave oven having a fan motor rotation control function comprising an absolute humidity sensor for sensing the humidity inside the microwave oven, a fan motor for discharging water vapor inside the microwave oven externally, a microprocessor and a keyboard. The improved microwave oven further comprises a phototriac connected between said fan motor and a supplying line of AC power source for controlling AC power supplied to the fan motor in accordance with a plurality of control signals from the microprocessor and a zero crossing signal generating circuit for detecting a zero point from AC power voltage during a constant cycle to generate a predetermined width of pulse signal at the zero point and for applying the predetermined width of pulse signal the microprocessor. The microprocessor is adapted for inputting the pulse signal from the zero crossing signal generating circuit and for outputting the plurality of control signals to said phototriac in response to the pulse signal for control of the phototriac in accordance with a plurality of command signals from the keyboard and a output signal from the absolute humidity sensor. Therefore, the microwave oven according to the present invention can freely adjust the number of rotations of the fan motor according to the menu of the dish, thereby enabling the inside humidity to be correctly sensed. 
Gold Star Co., Ltd.
H H
H02M H05B
inventional inventional
Jung R.
Kim