Power supply for magnetron in microwave oven or the like

Claim 2

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, an output circuit including the two capacitors connected in series across the terminals of the magnetron tube, a relay having a winding and a set of normally open contacts, the winding being subject to load current imposed by the magnetron and the normally open contacts being interposed in series with the second capacitor so that when the transformer is energized the voltage applied to the magnetron consists substantially of half-waves of voltage from the first half-wave voltage doubler circuit for positively initiating oscillation and for operation of the magnetron in a low power mode until the load current shortly thereafter causes the contacts to close to activate the second half-wave doubler circuit for continued oscillation of the magnetron thereafter in a high power mode.

Claim 3

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising transformer means having a primary winding and a high voltage secondary winding as well as a winding for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, means for applying the outputs of the voltage doubler circuits across the terminals of the magnetron tube, a set of switch contacts interposed in series with the second half-wave doubler circuit so that when the transformer means is energized with the contacts open the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for positively initiating oscillation and for operation of the magnetron in a low power mode, and means for closing the switch contacts following a brief time delay To activate the second half-wave doubler circuit for continued oscillation of the magnetron thereafter in a full wave high power mode.

Claim 4

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising transformer means having a primary winding and a high voltage secondary winding as well as a winding for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, means for applying the outputs of the voltage doubler circuits across the terminals of the magnetron tube, a set of switch contacts interposed in series with the second half-wave doubler circuit so that when the transformer means is energized with the contacts open the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for positively initiating oscillation and for operation of the magnetron in a low power mode, and means for closing the switch contacts following a brief time delay To activate the second half-wave doubler circuit for continued oscillation of the magnetron thereafter in a full wave high power mode.

Claim 5

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising transformer means for supplying filament current, a first source of half-wave voltage pulses, a second source of half-wave voltage pulses of complimentary phase, means for connecting the sources to the magnetron, means for simultaneously energizing the transformer means and connecting the magnetron to the first source of pulses to initiate oscillation, and means including a time delay device for connecting the magnetron additionally to the second source of pulses after a brief time delay.

Claim 6

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising transformer means for supplying filament current, a first source of half-wave voltage pulses, a second source of half-wave voltage pulses of complimentary phase, means for connecting the sources to the magnetron, means for simultaneously energizing the transformer means and connecting the magnetron to the first source of pulses to initiate oscillation, and means including a time delay device for connecting the magnetron additionally to the second source of pulses after a brief time delay.

Claim 7

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, the capacitors being connected to a common terminal so that the two capacitors are connected in series across the terminals of the magnetron tube, a relay having a winding and a set of normally open contacts for the purpose of providing time delay, the winding being connected in series with the magnetron so as to conduct load current flowing therein and the normally open contacts being interposed in series with the second capacitor so that when the transformer is energized the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for initiating oscillation and for operation of the magnetron in a low power mode until such time as the contacts close to connect the second half-wave doubler circuit for continued oscillation of the magnetron thereafter in a high power mode.

Claim 8

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, the capacitors being connected to a common terminal so that the two capacitors are connected in series across the terminals of the magnetron tube, a relay having a winding and a set of normally open contacts for the purpose of providing time delay, the winding being connected in series with the magnetron so as to conduct load current flowing therein and the normally open contacts being interposed in series with the second capacitor so that when the transformer is energized the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for initiating oscillation and for operation of the magnetron in a low power mode until such time as the contacts close to connect the second half-wave doubler circuit for continued oscillation of the magnetron thereafter in a high power mode.

Claim 9

The combination as claimed in claim 4 in which the transformer means for supplying the filament of the magnetron includes means for reducing the filament voltage and in which the relay includes auxiliary contacts for operating the voltage reducing means so that the filament voltage on the magnetron is reduced during operation in its high power mode.

Claim 10

The combination as claimed in claim 4 including a switch connected to the relay for effectively disabling the same to maintain the contacts open for sustained operation of the magnetron in the lower power mode.

Claim 11

The combination as claimed in claim 6 in which the disabling means is in the form of a switch connected in shunt with the relay winding for preventing response of the winding when the switch is in closed condition so that the output circuit is supplied substantially by the first half-wave doubler circuit for continued operation of the magnetron in the low power mode.

Claim 12

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, an output circuit including the two capacitors connected in series across the magnetron tube, a first relay having a winding and a set of normally open contacts, the winding being coupled to the output circuit so as to conduct magnetron load current and the normally open contacts being interposed in series with the second capacitor so that when the transformer is initially energized the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for initiating oscillation and for operation of the magnetron in a low power mode, and an auxiliary time delay relay coupled to the first relay for inhibiting the response of the latter to achieve a time delay before closure of the normally open contacts for subsequent operation of the magnetron in a high power mode.

Claim 13

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, an output circuit including the two capacitors connected in series across the magnetron tube, a first relay having a winding and a set of normally open contacts, the winding being coupled to the output circuit so as to conduct magnetron load current and the normally open contacts being interposed in series with the second capacitor so that when the transformer is initially energized the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for initiating oscillation and for operation of the magnetron in a low power mode, and an auxiliary time delay relay coupled to the first relay for inhibiting the response of the latter to achieve a time delay before closure of the normally open contacts for subsequent operation of the magnetron in a high power mode.

Claim 14

The combination as claimed in claim 8 in which the auxiliary relay is in the form of a time delay relay having a winding and set of normally closed contacts connected in series across the winding of the first relay and in which the time delay relay has a relatively low resistance so as to inhibit operation of the first relay until the normally closed contacts on the time delay relay have opened.

Claim 15

The combination as covered in claim 8 in which the first relay has a set of normally closed contacts which are interposed in series with the normally closed contacts of the time delay relay for the purpose of disabling subsequent operation of the time delay relay as long as the first relay is closed.

Claim 16

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising transformer means of the high reactance type having a primary winding and a secondary winding as well as a winding for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, the capacitors having a common connection, terminals at the junction of last diode and its associated capacitor to define an output circuit connected to the magnetron, relay means having a winding and a set of normally open contacts, the winding being connected into the circuit so as to be subject to magnetron load current and the normally open contacts being interposed in series with the second capacitor so that when the transformer means is turned on the voltage applied to the magnetron substantially in the form of spaced half-waves supplied from the first half-wave voltage doubler circuit for initiating oscillation and for operation of the magnetron in a low power mode until such time as the contacts close to activate the second half-wave doubler circuit for operation of the magnetron thereafter in a high power mode, the relay means being so constructed and arranged as to delay closing of the contacts until a brief time after the transformer is energized.

Claim 17

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising transformer means of the high reactance type having a primary winding and a secondary winding as well as a winding for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, the capacitors having a common connection, terminals at the junction of last diode and its associated capacitor to define an output circuit connected to the magnetron, relay means having a winding and a set of normally open contacts, the winding being connected into the circuit so as to be subject to magnetron load current and the normally open contacts being interposed in series with the second capacitor so that when the transformer means is turned on the voltage applied to the magnetron substantially in the form of spaced half-waves supplied from the first half-wave voltage doubler circuit for initiating oscillation and for operation of the magnetron in a low power mode until such time as the contacts close to activate the second half-wave doubler circuit for operation of the magnetron thereafter in a high power mode, the relay means being so constructed and arranged as to delay closing of the contacts until a brief time after the transformer is energized.

Claim 18

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, the capacitors having a common connection and the magnetron having its terminals connected to the doubler circuits between the diodes and their associated capacitors, and a set of contacts interposed in series with the second capacitor, means for delaying closure of the contacts so that when the transformer is energized the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for operation of the magnetron in a low power mode, and a high value resistor connected in parallel with the contacts for furnishing charging current to the second capacitor during operation in the low power mode thereby to reduce the inrush to the second capacitor when the contacts are subsequently cloSed for operation in a high power mode.

Claim 19

In a power supply for a magnetron tube in a microwave oven or the like, the combination comprising a transformer of the high reactance type having a primary winding and a secondary winding, transformer means for supplying the filament of the magnetron, a first half-wave voltage doubler circuit including a first diode and a first capacitor connected in series across the secondary winding, a second half-wave voltage doubler circuit including a second diode and a second capacitor connected in series across the secondary winding with the second diode being oppositely poled, the capacitors having a common connection and the magnetron having its terminals connected to the doubler circuits between the diodes and their associated capacitors, and a set of contacts interposed in series with the second capacitor, means for delaying closure of the contacts so that when the transformer is energized the voltage applied to the magnetron is derived substantially from the first half-wave voltage doubler circuit for operation of the magnetron in a low power mode, and a high value resistor connected in parallel with the contacts for furnishing charging current to the second capacitor during operation in the low power mode thereby to reduce the inrush to the second capacitor when the contacts are subsequently cloSed for operation in a high power mode.