Microwave output stabilizing apparatus of a microwave oven and a method thereof

• US 5,451,750 A
• Filed: 02/12/1993
• Issued: 09/19/1995
• Est. Priority Date: 02/14/1992
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Original Assignee: Samsung Electronics Co. Ltd. (Samsung Group)
• Inventors: An, Seong W.
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US08/017,298
• Time in Patent Office: 949 Days
• Field of Search: 219/10.55 B, 219/10.55 M, 219/715, 219/716, 219/717, 219/721, 363/96, 363/97, 363/49, 363/21
• US Class Current: 219/716
• CPC Class Codes: H02M 7/53846 Control circuits
• CPC Class Codes: H02M 7/53862 using transistor type converters
• CPC Class Codes: H05B 6/683 the measurements being made at the high voltage side of the circuit
• CPC Class Codes: H05B 6/685 the measurements being made at the low voltage side of the circuit

Abstract

A microwave output stabilizing apparatus for a microwave oven comprises a rectifier circuit for rectifying power from an AC power supply into a constant DC voltage; an invertor circuit for generating a high frequency power supply by controlling the DC voltage at an intermittent output state; a high voltage transformer for stepping up the high frequency power supply; and magnetron drive circuit for rectifying the high frequency power supply and oscillating a magnetron. Also, an inverter control circuit detects the current flowing into the primary winding of the high voltage transformer, converts the detected current into a corresponding voltage, the corresponding voltage with a reference voltage, and controls the inverter circuit according to the results of the comparison. Further included are an anode current detecting circuit for detecting the anode current of the magnetron and converting the detected anode current into the corresponding voltage; and, a reference voltage adjusting circuit for evaluating the anode current and changing the reference voltage of the invertor control circuit in accordance with the results of the evaluation.

Claims

1. A microwave output stabilizing apparatus for a microwave oven, comprising:

a rectifier circuit for rectifying power from an AC power supply into a constant DC voltage;

an inverter circuit for generating a high frequency power signal by controlling said DC voltage at an intermittent output state;

a high voltage transformer for stepping up said high frequency power signal;

a magnetron drive circuit including a magnetron for rectifying the stepped up high frequency power signal and causing a magnetron to oscillate;

an inverter control circuit for detecting a current flowing into a primary winding of said high voltage transformer, converting said detected current into a corresponding first voltage, comparing said corresponding first voltage with a reference voltage and controlling said inverter circuit according to a result of said comparing;

an anode current detecting circuit for detecting an anode current of said magnetron and converting said detected anode current into a voltage corresponding to a second voltage; and

a reference voltage adjusting circuit including a plurality of resistors and a microprocessor for determining whether the detected anode current is within a predetermined range thereof and for controlling a parallel connection of said resistors to control said reference voltage to be applied to said inverter control circuit in accordance with said voltage corresponding to said detected anode current.

2. The microwave output stabilizing apparatus for a microwave oven according to claim 1, further comprising an over-current protecting circuit for controlling said inverter control circuit by determining whether said magnetron is short circuited based on said second voltage corresponding to said detected anode current.

3. The microwave output stabilizing apparatus for a microwave oven according to claim 1, further comprising a soft start circuit for controlling said inverter control circuit by determining whether said magnetron is in an initial run state based on said second voltage corresponding to said detected anode current.

4. A microwave output stabilizing apparatus for a microwave oven, comprising:

a rectifier circuit for rectifying power from an AC power supply into a constant DC voltage;

an inverter circuit for generating a high frequency power signal by controlling said DC voltage at an intermittent output state;

a high voltage transformer for stepping up said high frequency power signal;

a magnetron drive circuit including a magnetron for rectifying the stepped up high frequency power signal and causing a magnetron to oscillate;

an inverter control circuit for detecting a current flowing into a primary winding of said high voltage transformer, converting said detected current into a corresponding first voltage, comparing said corresponding first voltage with a reference voltage and controlling said inverter circuit according to a result of said comparing;

an anode current detecting circuit for detecting an anode current of said magnetron and converting said detected anode current into a voltage corresponding to a second voltage; and

a reference voltage adjusting circuit for controlling said reference voltage of said inverter control circuit in accordance with said voltage corresponding to said detected anode current, said reference voltage adjusting circuit including

a plurality of resistors selectably connectable to control a voltage to be presented to said inverter control circuit, and

a microprocessor including an A/D input and a plurality of output ports, said A/D input being connected to said anode current detecting circuit to receive said second voltage, said microprocessor determining whether the anode current is within a predetermined range on the basis of said second voltage and producing an output collectively at said plurality of output ports based on said determination, said output controlling connection of said plurality of resistors.

5. The microwave output stabilizing apparatus for a microwave oven according to claim 4, further comprising an over-current protecting circuit for controlling said inverter control circuit by determining whether said magnetron is short circuited based on said second voltage corresponding to said detected anode current.

6. The microwave output stabilizing apparatus for a microwave oven according to claim 4, further comprising a soft start circuit for controlling said inverter control circuit by determining whether said magnetron is in an initial run state based on said second voltage corresponding to said detected anode current.