US4825028A — Magnetron with microprocessor power control

Claim 1

Independent Claim 173 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; a full wave full bridge inverter connected to supply power to said primary by selectively switching pairs of four controlled switches; a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said four controlled switches; and a microprocessor having a first output port, said first output port connected to said control circuit and operable for starting and stopping the switching of said four controlled switches, and wherein said first output port is operable to supply a power control signal of variable duty cycle and said control circuit further including means responsive to said power control signal and said oscillator to provide gating signals to said controlled switches as a function of the state of said power control signal whereby the duty cycle of the power control signal controls the power of said magnetron.

Claim 2

Dependent Claim 173 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; a full wave full bridge inverter connected to supply power to said primary by selectively switching pairs of four controlled switches; a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said four controlled switches; and a microprocessor having a first output port, said first output port connected to said control circuit and operable for starting and stopping the switching of said four controlled switches, and wherein said first output port is operable to supply a power control signal of variable duty cycle and said control circuit further including means responsive to said power control signal and said oscillator to provide gating signals to said controlled switches as a function of the state of said power control signal whereby the duty cycle of the power control signal controls the power of said magnetron.

Claim 3

Dependent Claim 22 words

The microwave energy generating system of claim 1 wherein said gating pulses have a duty cycle independent of the power control signal.

Claim 4

Dependent Claim 43 words

The microwave energy generating system of claim 1 wherein the duty cycle of said power control signal controls the power of said magnetron by causing said control circuit to operate said inverter for variable ON time intervvals interspersed with variable OFF time intervals.

Claim 5

Dependent Claim 47 words

The microwave energy generating system of claim 1 further comprising a filament sensor for sensing a condition of a filament of the magnetron and, wherein said microprocessor is connected to receive a signal from said filament sensor and is operable to monitor said condition of said filament.

Claim 6

Dependent Claim 68 words

The microwave energy generating system of claim 1 further comprising a magnetron sensor for generating a signal depending on the magnetron power, and wherein said microprocessor is connected to receive the signal from the magnetron sensor and is operable to adjust the inverter frequency for changing the magnetron power until the signal from said magnetron sensor is brought to a set point corresponding to a desired magnetron power.

Claim 7

Dependent Claim 165 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; and a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; and a microprocessor having a first output port operable to supply a power control signal of variable duty cycle to control circuit; and wherein the duty cycle of said power control signal controls the power of said magnetron, and wherein said control circuit includes a logic circuit connecting said oscillator to have controlled switches, said first output port being connected to supply the power control signal as a logic signal to said logic circuit, said logic circuit selectively providing said gating signals to said controlled switches as a function of the state of said power control signal.

Claim 8

Dependent Claim 165 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; and a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; and a microprocessor having a first output port operable to supply a power control signal of variable duty cycle to control circuit; and wherein the duty cycle of said power control signal controls the power of said magnetron, and wherein said control circuit includes a logic circuit connecting said oscillator to have controlled switches, said first output port being connected to supply the power control signal as a logic signal to said logic circuit, said logic circuit selectively providing said gating signals to said controlled switches as a function of the state of said power control signal.

Claim 9

Dependent Claim 22 words

The microwave energy generating system of claim 6 wherein said gating pulses have a duty cycle independent of the power control signal.

Claim 10

Dependent Claim 42 words

The microwave energy generating system of claim 6 wherein an ON time interval corresponds in duration to said power control signal having a first level and said OFF time interval corresponds in duration to said power control signal having a second level.

Claim 11

Dependent Claim 55 words

The microwave energy generating system of claim 6, wherein the duty cycle of said power control signal controls the power of said magnetron by causing said control circuit to operate said inverter for variable ON time intervals interspersed with variable OFF time intervals, each ON time interval corresponding to a cluster of said gating pulses.

Claim 12

Dependent Claim 24 words

The microwave energy generating system of claim 9 wherein said inverter is a full wave full bridge inverter having four of said controlled switches.

Claim 13

Dependent Claim 47 words

The microwave energy generating system of claim 9 further comprising a filament sensor for sensing a condition of a filament of the magnetron and, wherein said microprocessor is connected to receive a signal from said filament sensor and is operable to monitor said condition of said filament.

Claim 14

Dependent Claim 155 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; and a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; and a filament sensor for sensing a condition of a filament of said magnetron; and a microprocessor connected to receive a signal from said filament sensor and operable to monitor said condition of said filament, and wherein said power transformer further includes a filament powering secondary, and wherein said microprocessor causes said system to operate in a filament standby mode upon start up with the magnetron being off and said inverter operating to supply warm up power to said filament by way of said filament powering secondary.

Claim 15

Dependent Claim 155 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; and a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; and a filament sensor for sensing a condition of a filament of said magnetron; and a microprocessor connected to receive a signal from said filament sensor and operable to monitor said condition of said filament, and wherein said power transformer further includes a filament powering secondary, and wherein said microprocessor causes said system to operate in a filament standby mode upon start up with the magnetron being off and said inverter operating to supply warm up power to said filament by way of said filament powering secondary.

Claim 16

Dependent Claim 33 words

The microwave energy generating system of claim 12 further comprising: a filament standby control switch, said filament standby control switch operable in said filament standby mode to lower the voltage to said primary.

Claim 17

Dependent Claim 37 words

The microwave energy generating system of claim 13 further comprising a resistor in parallel to said filament standby control switch and operable to lower the voltage supplied to said inverter when said filament standby switch is open.

Claim 18

Dependent Claim 17 words

The microwave energy generating system of claim 12 wherein said condition is the current in said filament.

Claim 19

Dependent Claim 24 words

The microwave energy generating system of claim 15 wherein the filament sensor senses the filament current indirectly by sensing the current in said primary.

Claim 20

Dependent Claim 20 words

The microwave energy generating system of claim 16 wherein the filament sensor comprises a resistor sensing current through said primary.

Claim 21

Dependent Claim 38 words

The microwave energy generating system of claim 17 further comprising a peak detector to detect a peak voltage across said resistor and an A/D converter receiving said peak voltage and supplying a corresponding digital signal to said microprocessor.

Claim 22

Dependent Claim 29 words

The microwave energy generating system of claim 15 wherein said microprocessor is operable to delay the operation of the magnetron until the filament current has warmed up said filament.

Claim 23

Dependent Claim 37 words

The microwave energy generating system of claim 19 wherein said microprocessor has a first output port, said first output port connected to said control circuit and operable for starting and stopping the switching of said controlled switches.

Claim 24

Dependent Claim 41 words

The microwave energy generating system of claim 20 wherein said first output port is operable to supply a power control signal of variable duty cycle and wherein the duty cycle of said power control signal controls the power of said magnetron.

Claim 25

Dependent Claim 24 words

The microwave energy generating system of claim 21 wherein said inverter is a full wave full bridge inverter having four of said controlled switches.

Claim 26

Dependent Claim 140 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; a control circuit for controlling the operation of said inverter, said circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; a magnetron sensor for generating a signal depending on the magnetron power; and a microprocessor connected to receive the signal from said magnetron sensor and operable to adjust the operation of the inverter for changing the magnetron power until the signal from said magnetron sensor is brought to a set point corresponding to a desired magnetron power, wherein said microprocessor is operable to change the magnetron power by changing the frequency of said inverter.

Claim 27

Dependent Claim 140 words

A microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; a control circuit for controlling the operation of said inverter, said circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; a magnetron sensor for generating a signal depending on the magnetron power; and a microprocessor connected to receive the signal from said magnetron sensor and operable to adjust the operation of the inverter for changing the magnetron power until the signal from said magnetron sensor is brought to a set point corresponding to a desired magnetron power, wherein said microprocessor is operable to change the magnetron power by changing the frequency of said inverter.

Claim 28

Dependent Claim 23 words

The microwave energy generating system of claim 23 wherein said magnetron sensor senses the magnetron power indirectly by sensing current in said primary.

Claim 29

Dependent Claim 34 words

The microwave energy generating system of claim 23 wherein said microprocessor is operable to compare the signal from said magnetron sensor with different set points depending upon an operator selection of desired magnetron power.

Claim 30

Dependent Claim 24 words

The microwave energy generating system of claim 23 wherein said inverter is a full wave full bridge inverter having four of said controlled switches.

Claim 31

Dependent Claim 151 words

The microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; a magnetron sensor for generating a signal depending on the magnetron power; and a microprocessor connected to receive the signal from said magnetron sensor and capable to adjust the operation of the inverter for changing the magnetron power until the signal from said magnetron sensor is brought to a set point corresponding to a desired magnetron power, and wherein the microprocessor is operable to adjust the operation of the inverter for changing the magnetron power without changing the duty cycle of the gating pulses.

Claim 32

Dependent Claim 151 words

The microwave energy generating system comprising: a magnetron operable to generate microwave energy for cooking; a power transformer having a primary and a magnetron powering secondary; an inverter connected to supply power to said primary by selectively switching controlled switches; a control circuit for controlling the operation of said inverter, said control circuit having an oscillator and operable to generate gating pulses to switch said controlled switches; a magnetron sensor for generating a signal depending on the magnetron power; and a microprocessor connected to receive the signal from said magnetron sensor and capable to adjust the operation of the inverter for changing the magnetron power until the signal from said magnetron sensor is brought to a set point corresponding to a desired magnetron power, and wherein the microprocessor is operable to adjust the operation of the inverter for changing the magnetron power without changing the duty cycle of the gating pulses.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-04-24	1992-10-24	1993-04-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-04-24	1996-10-24	1997-04-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-04-24	2000-10-24	2001-04-25	$7700.00	Window Closed / Lapsed

Magnetron with microprocessor power control

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