Output power control system for microwave ovens

An output power control system for a microwave oven, comprising:

• an AC power source;
• a magnetron tube for microwave oscillation;
• switch means and a semiconductor element connected in series between said AC power source and said magnetron tube for controlling the power to said magnetron tube;
• a DC power source coupled to said AC power source;
• and
• an output power control circuit coupled to said DC power source and supplying first and second control signals to said switch means and said semiconductor element, respectively;
• said output power control circuit comprising:
• a door signal generating means coupled to said DC power source for producing door signals representing the open and closed state of a door of said microwave oven;
• an initiating pulse generating means coupled to said DC power source for producing a pulse to initiate the operation of said output power control circuit when said AC power source is turned on;
• a main control section receiving said door signal and said initiating pulse for periodically detecting said door signals, said main control section producing first and second set signals when said door is closed at said periodic detection and producing first and second reset signals when said door is opened at said periodic detection;
• and
• an output control section coupled to said door signal generating means, said initiating pulse generating means, said main control section, said switch means, and said semiconductor element, said output control section comprising first means which produces said first and second control signals for causing said magnetron tube to oscillate when receiving said first and second set signals and which stops producing said first and second control signals when receiving said first and second reset signals, and second means which instantaneously stops said first and second control signals when said door is opened during the oscillation period of said magnetron tube.