System and method for regulating power output in a microwave oven
AssigneeLitton Systems, Inc.
InventorRonald R. Lentz
Life of this patent
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Abstract
A method and control system for regulating the output power of a magnetron in a microwave oven having a food heating cavity, a magnetron, and a waveguide coupling the magnetron to the heating cavity. The reflection coefficient within the waveguide is measured and a control signal is generated to switch the magnetron between first and second levels of power output when the reflection coefficient reaches a pre-determined value indicating that the food item within the oven has begun to defrost. In the preferred embodiment, the present invention incorporates digital signal processing utilizing a microprocessor to calculate the reflection coefficient and generate the control signal based upon digital signal inputs that are a function of the detected microwave energy within the waveguide.
Claims19
In a microwave oven having a food heating cavity, a magnetron, and waveguide means for coupling the magnetron to the heating cavity, means for controlling the microwave oven heating cycle comprising:
- (a) detector means coupled to the microwave oven for measurement of the microwave reflection coefficient within the oven;
- and
- (b) means connected to said detector means and to the magnetron for regulating the power output of the magnetron in response to said measured reflection coefficient.
In a microwave oven having a food heating cavity, a magnetron, and waveguide means for coupling the magnetron to the food cavity, means for controlling the microwave heating cycle comprising:
- (a) a directional coupler coupled to the waveguide means;
- (b) first and second square law detectors having input probes disposed proximate opposite ends of said directional coupler, said first and second square law detectors generating first and second output signals proportional to the forward and reflected power, respectively, within the waveguide means;
- (c) means connected to the outputs of said first and second square law detectors for generating a control signal representative of the reflection coefficient within the microwave oven;
- and
- (d) means responsive to said control signal for regulating the power output of the magnetron.
In a microwave oven having a food heating cavity, a magnetron, and waveguide means for coupling the magnetron to the food cavity, means for controlling the microwave oven heating cycle comprising:
- (a) three square law detectors having input probes disposed linearly within the waveguide means and spaced apart .lambda./8 where .lambda. is the wavelength of the microwaves at the operating frequency of the oven, said detectors having output signals proportional to the power input to said detectors;
- (b) means connected to the outputs of said detectors for generating a control signal representative of the reflection coefficient within the waveguide means;
- and
- (c) means connected to said control signal generating means and responsive to said control signal for regulating the power output of the magnetron.
In a microwave oven having a food heating cavity, a magnetron, and a waveguide means coupling the magnetron to the cavity, a method of controlling the heating process comprising the steps of:
- (a) detecting the microwave reflection coefficient within the oven;
- (b) generating a control signal in response to the detected reflection coefficient;
- and
- (c) regulating the power output of the magnetron in response to said control signal.
In a microwave oven having a food heating cavity, a magnetron, and waveguide means for coupling the magnetron to the heating cavity, means for controlling the microwave oven heating cycle comprising:
- (a) detector means coupled to the waveguide means for measurement of the forward and reflected power within the waveguide means;
- and
- (b) means connected to said detector means and to the magnetron for regulating the power output of the magnetron in response to said measured forward and reflected power.
Dependencies are inferred from the claim text.