DE2263136A1 - MICROWAVE GENERATOR - Google Patents

Description

Patent attorney * · "

R: fti! Sf? IKÄ Munich, December 22nd, 1972 / me

Dr. rer. nat. W. K δ R B E R

Dipl. · In,?. J. SCHMIDT- EVER *.

MUNICH 22, Stotnsdorfstr. 19th

Miratron AG , Basel

CH-4004 Basel
Johanniterstr. 11

Microwave generator

V patent application

The invention relates to a microwave generator, especially for supplying --heating devices, e.g. Microwave oven.

It is known that electron tubes, mainly magnetrons of the incandescent cathode type, are used to generate microwaves for ^{: the} purpose mentioned

can. These tubes are designed so that the The voltages required for their operation are supplied by at least two separate transformers, whereby - one the heating voltage of about 5 V and - the other the high voltage required to operate the tube

19 * 12.72 / GE / gl. '*; ■'.

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supplies voltage from 3 to 15 kV.

It is also known to use capacitors connected in series with the latter transformer Control and in particular to simplify this transformer to use. To the tube, the capacitors and to protect the transformers from damage, preferably during commissioning, must be such Means can be provided with a delay unit, the switching on of the high voltage transformer delayed until the cathode has reached the temperature required for the operation of the tube. All these Precautions make the known microwave generators quite complicated devices.

To remedy these disadvantages, a microwave generator with a hot cathode tube is proposed, which is characterized by a single supply of all voltages required for the operation of the hot cathode tube Transformer, one connected in series with one terminal of the high-voltage winding of the transformer Capacitor arrangement with at least one series capacitor and one connected in series with the capacitor arrangement Impedance arrangement with a switching element, which determines the impedance value after a period of time that depends on the time " until the operating temperature of the hot cathode tube is reached, greatly reduced. .

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The subject matter of the invention is based on below in a drawing, for example * It shows

Fig. 1 in a rare plan the generator with partial open housing, and ■

Fig. 2 is a circuit diagram of the generator according to Flg. 1. ■

A housing 1 made of die-cast aluminum contains a transformer 2 and three capacitor units connected in series 3A, 3B and 3C, a rectifier 4, a fan 5, a microswitch 6, a resistor 7 »an electron tube 8 with cooling fins 9 and two magnets 10, 11. The transformer 2 has one Primary winding 21 and two secondary windings 23 and 24, the latter only being coupled to the primary winding via a core 22 of wound magnetic tape material are. The first secondary winding 23 is for Delivery of the relatively / low heating voltage for the, tube 8, the second secondary winding for the delivery of the High voltage intended for the operation of the tube «Je one terminal of each of the secondary windings is connected to the Cathode connected to the tubes. The other terminal of the high voltage circuit 24 is across capacitors 3A to 3C and the resistor 7 to the anode of the tube 8 connected. The rectifier 4 is parallel in this way

f 8 7:18

switched to the tube that current in opposite directions either through the rectifier

4 or can flow through the tube 8 »,

The switch 6 is parallel to the resistor and is used to activate the resistor to close briefly. The anode of the tube 8, the resistor 6, the switch 7 and the negative pole of the rectifier 4 are grounded or connected to the housing 1. An operating lever 6l on the switch 6 carries a profiled Flag 62 made of light metal, the so on the fan

5 is arranged to be generated by the Airflow is actuated. The main task of the fan 5 is. Cooling air over the cooling fins 9 the tube 8 to blow.

The cooling air is through a lattice-covered opening located in a side wall of the housing 1 12 sucked in, and leaves this through a second, also lattice-covered opening 13 in an end wall of the housing after it has flowed along the cooling fins 9. The housing 1 has a cross-shaped plan Cross-section to ensure maximum rigidity and good shielding of all those parts of the generator to achieve, which conduct high-frequency currents, except ~ men the starting game 14.-

One of the cross arms contains the transformer

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core 22 and is precisely adapted to its shape. The other Cross arm contains the windings. Between the primary and the secondary winding there is a solid · wall arranged to support the transformer core and the primary winding 21 completely from the action of high frequency currents in others Shields parts of the generator.

. The generator works as follows: After connection To a power source, the transformer supplies a low voltage for the through the winding 23 Cathode heating of the tube 8 ... At the same time, the capacitors 3A to 3C begin to charge via the resistor 7 through the other secondary winding 24, and the Fan 5 starts to run. After a few seconds the fan speed is so high that the the air flow acting on the flag 62 closes the switch 6 by means of the lever 6l. During this relatively For a short time the cathode of the tube 8 is heated to a temperature at which the tube can work immediately begins as soon as the anode voltage is short-circuited by the resistor 7 by means of the switch 6 reached their full value. Of course, the run-up time of the fan must be at least as long be like the time it takes to heat the cathode. The total capacitance of capacitors 3A to 3C and

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the resistor 7 must also be on top of each other in order to achieve the full charge voltage at the same time period be coordinated.

Typical values for achieving this are with a cathode heating time of 7 seconds: total capacity of capacitors 1 uF, resistance 1 M λ, with correct adjustment the load on the switch so weak that an ordinary microscope holder can be used. The switch only has to switch off the circuit in the event of an interruption of the air flow, before the generator is disconnected from the supply current source.

In addition to this exemplary embodiment of the subject matter of the invention, variants are also possible. In such an embodiment, two series-connected capacitors for providing 100 pulses / second from a 50 Hz network can be provided in a manner not shown for doubling the voltage. In this case it is sufficient that a series resistor and a switch according to parts 6 and 7 are assigned to one of the capacitors, as shown in FIG. ¹ In another variant embodiment of the subject matter of the invention, the resistor 7 is replaced by a different impedance, "for example a self-induction coil or a semiconductor element. The impedance can then be short-circuited by

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2163138

Applying a weak direct current component or
be replaced via a control electrode in a semiconductor element ». '.

In a third version it can the change in impedance caused by the capacitor combination lying voltage, either by means of a relay or through a bistable semiconductor device be effected,

3 09 82 8/0798

Claims (1)

2263f36 Claim Microwave generator with a hot cathode tube, characterized by a single «all for the Operation of the hot cathode tube required voltages supplying transformer (21-24), one in series with the one terminal of the high-voltage winding (24) connected capacitor arrangement (3A-3C) with at least a series capacitor, and a Xinpcdunιημίογ <ΙT connected in series to the capacitor arrangement (6,7) with a switching element which determines the impedance value after a period of time that extends from the time to Reaching the operating temperature of the hot cathode tube is dependent, greatly reduced. 30 9}.:? R / 0798 ORIGINAL INSPECTED Blank page