EP3977817A1

EP3977817A1 - Household microwave device comprising a detection unit for detecting microwave leakage radiation

Info

Publication number: EP3977817A1
Application number: EP20728747.5A
Authority: EP
Inventors: Christian Böttcher; Andreas Kaiser; Markus Kuchler
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2019-05-30
Filing date: 2020-05-27
Publication date: 2022-04-06
Anticipated expiration: 2040-05-27
Also published as: EP3977817B1; DE102019207978A1; WO2020239830A1; CN113853832A

Abstract

The invention relates to a household microwave device (1) comprising a cooking chamber (2) and at least one detection unit (10, 11) for detecting microwave leakage radiation outside the cooking chamber (2), wherein the detection unit (10, 11) has at least one antenna line (11) in which alternating currents can be induced by microwaves, and an evaluation circuit (10) connected to the at least one antenna line (11) and designed for determining alternating currents induced in the at least one antenna line (11), and wherein the at least one antenna line (11) has at least one further function. The invention can be, in particular advantageously, used in ovens with a microwave function and independent microwave ovens.

Description

Household microwave device with detection device for detecting microwave leakage radiation

The invention relates to a household microwave appliance, comprising a cooking chamber and at least one detection device for detecting microwave leakage radiation outside the cooking chamber, the detection device having at least one antenna line in which alternating currents can be induced by microwaves, and one connected to the at least one antenna line Evaluation circuit which is designed to determine alternating currents induced in the at least one antenna line has. The invention also relates to a method for operating the household microwave appliance. The invention is particularly advantageously applicable to baking ovens with a microwave function and stand-alone microwave ovens.

EP 2 152 047 A1 discloses a safety device for detecting leakage radiation in a cooking device with a microwave function and a cooking device with such a safety device. The safety device comprises at least one microwave sensor which comprises a probe in which an alternating current can be induced by leakage radiation, or which is suitable for tapping alternating currents that are induced in other objects by leakage radiation. The sensor also includes a fuse through which the alternating current is passed. Finally, the safety device comprises a device which is suitable for switching off a microwave source of the cooking appliance as soon as the safety device trips.

EP 2 148 553 A1 discloses methods for microwave leakage monitoring. In the case of a cooking appliance, a microwave leakage radiation emerging from the cooking space is detected by means of a microwave sensor device and its course over time is stored. A subsequent evaluation of the stored microwave radiation values can include, in particular, a prognosis of the future temporal course of the detected microwave radiation and the early signaling of a predefined threshold value being exceeded on the basis of the prognosticated course. A corresponding device for microwave leakage monitoring and a cooking appliance equipped with such a device are also disclosed. DE 2 029 559 A1 discloses a safety device against the escape of radiation from microwave devices, whereby at least one microwave-responsive gas tube is used, which is arranged in the vicinity of the zone of a possible radiation exit and is electrically connected to the control circuit of a controlled semiconductor diode, which in turn is in the supply circuit of a relay, the excitation of which causes the electrical supply circuit of a microwave generator to open.

DE 195 37 755 A1 discloses a microwave oven, especially for a laboratory, with a heating chamber surrounded by a housing, into which microwaves can be coupled and which is accessible through a closable access opening. In the area of a gap in the housing emanating from the heating chamber, a microwave sensor is arranged in such a way that when microwave radiation exceeding a certain value enters and / or passes through the gap, the sensor activates the emission of a warning signal or the microwave exposure of the heating chamber turns off.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and, in particular, to provide an improved possibility of detecting a leakage of microwaves emerging from a cooking space of a domestic microwave appliance.

This object is achieved according to the features of the independent claims. Advantageous embodiments are the subject of the dependent claims, the description and the drawings.

The object is achieved by a household microwave appliance, having a cooking space and at least one detection device for detecting microwave leakage radiation outside the cooking space, wherein

- The detection device has at least one electrically conductive line ("antenna line") in which alternating currents can be induced by microwaves, and an evaluation circuit connected to the at least one antenna line which is designed to determine alternating currents induced in the at least one antenna line and in which

- The at least one antenna line has at least one further function. This household microwave appliance has the advantage that no separate electrical line is required to detect a leakage of microwaves. This in turn advantageously enables a particularly cost-effective structure. In addition, the antenna line can have a great length and be laid in various ways in the household microwave device. This has the advantage that large areas of the household microwave device outside the cooking chamber can be monitored for microwave leakage with one antenna line, which means that the number of detection devices and / or their components compared to microwave detection devices that only measure point-wise can be reduced. A particularly reliable and cost-effective structure is thus made possible. A further advantage is that the evaluation circuit can be arranged remotely from leakage radiation sources in areas of the household microwave appliance that are not subject to much thermal, chemical and / or electromagnetic stress. The antenna cables, on the other hand, are noticeably more resistant and can easily pass through thermally and chemically stressed (eg hot and / or humid) areas. Another advantage is that microwave leaks can be detected with high sensitivity. In this way, impending high microwave leaks in the device can be detected at an early stage. This in turn has the effect of reducing the potential risk to users and customer service employees. In addition, the early detection of a microwave leak enables customer service to be carried out at such an early stage that a leakage source can be sealed and the functionality of the device can be fully restored without causing a component failure. For example, changes in the device such as component distortion (gaps open) or corrosion of metallic walls (rust holes in a cooking chamber wall) or an increase in contact resistance due to oxidation or corrosion (such as deteriorating electrical contact from electrical contact foils or sealing braids at, for example, waveguide-muffle junctions or radiator flanges), sources of leakage radiation can be detected at an early stage and corrected by customer service. For example, a microwave leakage can lead to interference (eg fluctuating power consumption) of an inverter or a microwave generator, as a result of which both the inverter and a magnetron can be destroyed by overload. This also saves time for customer service in troubleshooting, and a customer service representative can take components to be replaced to the customer right away. The household microwave device can be a cooking device with a microwave function, in particular a special oven with an additional microwave function, a stand-alone microwave device or a microwave device with additional IR heating elements such as resistance heating elements, IR radiators, etc.

A household microwave appliance typically has at least one microwave generator such as a semiconductor-based microwave generator or a magnetron in order to generate microwaves, by means of which the goods in the cooking space can be treated or acted upon. The microwave frequency can be in the range of 915 MHz or 2.45 GHz, for example. The microwave generator can feed the microwaves into the cooking space directly or via a microwave guide. In addition, means for distributing the microwaves in the cooking chamber, such as, in particular, rotatable feed antennas, mode stirrers, wobblers, etc., can be present. The generation and introduction of microwaves into the cooking space is generally well known and is therefore not discussed further here.

The microwave detection device is used to detect microwave leakage radiation outside the cooking space, in particular microwave leakage radiation in an area of the household microwave device between a cooking space wall (hereinafter also referred to as "muffle") and an outer housing, but also in door gaps etc.

The antenna line is an electrically conductive, in particular metallic, line, e.g. a conductor track, wire, cable, etc., in which alternating currents can be induced by means of the microwave generator generated by microwaves.

The evaluation circuit is set up in particular to determine the strength of a microwave-induced current induced in the at least one antenna line, which is a measure of the strength of the leakage or leak rate. The evaluation circuit can have one or more electrical and / or electronic components and / or functional units such as capacitors, resistors, processors (for example microcontrollers, ASICs, FPGAs), rectifiers, A / D converters, etc. In one development, an evaluation circuit can be connected to precisely one antenna line and therefore only evaluate this antenna line or determine the strength of a microwave-induced current induced in this antenna line. It is an alternative development that an evaluation circuit is connected to several antenna lines. In this case, several antenna lines can be evaluated jointly by the evaluation circuit. The joint evaluation enables a particularly simple and inexpensive detection device to be provided. The covered or detectable detection area can also be enlarged as a result, so that the evaluation unit can respond earlier in the event of a leak.

In a further development, several antenna lines can be electrically brought together and connected to the evaluation circuit at a common node. Alternatively, several antenna lines can be evaluated individually using the same evaluation circuit, e.g. separated or in parallel. The individual evaluation enables an improved localization of a leakage source.

Alternatively, the household microwave appliance can contain several e.g. each having an antenna line connected evaluation circuits. These can be arranged distributed over the household microwave device.

It is a further development that the at least one antenna line has or performs at least one further function, at least in sections. In particular, an electrical line that is already present for another purpose can also be used as an antenna line. A line having the at least one further function would thus also be present in the device if it were not used to detect the microwave leakage.

It is an embodiment that the at least one further function comprises a power supply function for supplying at least one electrical consumer of the household microwave appliance with electrical energy and / or a data transmission function. In other words, at least one antenna line is a power supply line for at least one electrical consumer and / or a data transmission line. The ("load") current used to operate the consumer can be a direct current or an alternating current. Such antenna lines have the advantage that they are typically designed to be the same over their length and / or have a defining th, have particularly low electrical resistance. As a result, in turn, a particularly precise and reliable detection or evaluation of the alternating currents induced by micro waves therein can be achieved. Another advantage is that antenna lines of this type typically connect functional units to one another, which are located in room areas of the household microwave appliance that are not exposed to much thermal and / or chemical and / or electromagnetic stress. As a result, the evaluation circuit can also be arranged in these areas with little or no adaptation effort on end sections of the antenna lines.

In principle, however, it is also possible to use other electrically conductive components of the household microwave device that fulfill a mechanical function, for example, as antenna cables, in particular elongated components such as struts, fastening wires, etc. In this case, it may be necessary to replace the components with additional cable sections in the form e.g. of wires to the evaluation circuit so that the evaluation circuit can be accommodated in a thermally and / or chemically less stressed area and / or to enable an electrical connection to the evaluation circuit. The additional line sections can be soldered to the electrically conductive components, etc.

It is an embodiment that the at least one electrical consumer comprises a heating element, a light generating device, a motor, a power supply device and / or electronics (e.g. a control board) etc. The heating element can e.g. be a resistance heating element for heating the oven or a vaporizer. The light generating device can e.g. be or have a lamp or other lighting device, for example to illuminate the cooking space, control elements or decorative elements. The motor can e.g. be a motor for moving a rotating antenna, a roasting spit, a fan, a flap (e.g. a steam flap), a turntable, a cooking chamber door, a pump, etc. In principle, however, the at least one electrical consumer is not restricted to this and can be any other consumer such as a control panel or component thereof, a camera, a communication module (e.g. a WLAN or Ethernet module), etc.

It is an embodiment that at least one antenna line has at least one data transmission function and with at least one no electrical consumer rather representing functional unit of the device is connected, for example with a sensor, a reed contact or other magnetic switch, etc. This case can exist, for example, when the non-power-consuming functional unit is a sensor, for example a temperature sensor, especially temperature sensor. However, there are also sensors that represent electrical consumers, for example oxygen sensors in the form of lambda probes, which have a heating element. If the functional unit that does not represent an electrical consumer is a reed contact, in one variant this could only switch signal levels (with a microcontroller evaluating the switching state, for example), and in another variant, for example, an excitation current of a relay coil. The cabling of both reed contacts would be suitable antenna lines.

An electrical line can also be set up or used as an antenna line, which serves both for power supply and for data transmission, e.g. by modulating a power supply signal with a data signal. In principle, an electrical consumer can be connected both to a dedicated power supply line and to a dedicated data line, one or more of which can serve as an antenna line.

One embodiment is that at least one antenna line has at least one section, the shape and / or position of which is determined (only) by the function of the antenna line for detecting the microwave leakage radiation. This section therefore does not contribute to the implementation of the further function of the antenna line or can even have a negative effect on it (even if typically only slightly). The advantage of such a section is that it is shaped and / or relocated for improved detection of microwave leakage radiation and thus enables its particularly reliable detection. The section can for example be placed through or around areas of openings in a cooking chamber wall. Due to the increased length, its ohmic resistance is increased, but this need only have a negligibly small or practically no effect on its power line and / or data transmission function. The section can also be twisted (e.g. meandering).

It is an embodiment that at least one antenna line at least a length of at least 800 mm, in particular of at least 1000 mm, in particular of at least 1500 mm, in particular of at least 2000 mm. Such a long length results in the advantage that as many / large areas as possible inside the housing of the household microwave device can be covered with an antenna line and locally distributed sources of leakage radiation can be sensed or detected with a small number of antenna lines.

Since the sources of leakage radiation are not only spatially distributed, but often also radiate differently over time (for example due to the temporally different mode distribution in the cooking space due to the movement of a feed antenna, a mode stirrer and / or a turntable), it is advantageous that the antenna line has a local and possibly also has a time-integrating property. The superposition of the various radiated microwave signals then results in the sum signal applied to the microwave sensor. This superposition is more pronounced the longer the antenna cable is.

It is an embodiment that the microwave detection device additionally has at least one electrically conductive line in which alternating currents can be induced by microwaves, which is connected to the evaluation circuit and which does not carry any other signal (ie no current and / or data) ) Has function, in particular has no other function. Such a line is referred to below as a "sniffer line". The sniffer line is therefore only laid for the purpose of detecting microwave-based induction. The household microwave appliance can consequently be designed such that the evaluation circuit is connected to at least one antenna line (which also fulfills at least one further function) and to at least one sniffer line (without a dedicated further function). Providing a sniffer line has the advantage that it can be laid in the device in a particularly variable manner, e.g. because it is functionally connected to the evaluation circuit at one end, but the other end is a freely positionable end. A sniffer line can basically be designed and / or connected analogously to an antenna line. As a sniffer line, e.g. a wire, a cable, a conductor track applied to a substrate, etc. can be used.

It is a further development that at least one evaluation circuit is an independent component of the household microwave appliance, separated from a control device is arranged and verbun via at least one signal line with the control device is the. This has the advantage that at least one evaluation circuit can be positioned particularly flexibly in the household microwave appliance. As an output signal or output information, the evaluation circuit can in particular supply information about the strength of the microwave-induced alternating current. The output signal or the output information can be in analog or digital form. The output signal or the output information can be used by the control device to assess whether at least one action associated with the strength of the leak rate should be triggered, as will be described in more detail below.

It is an embodiment that the evaluation circuit is integrated in a control device of the household microwave appliance. This has the advantage that the evaluation circuit is accommodated in a space which is particularly well suited or provided for accommodating electrical and / or electronic components. This is particularly advantageous if the control device is housed in a specially protected compartment, compartment or compartment that is, for example, thermally insulated and / or ventilated to cool the evaluation unit. Another advantage is that the signal paths between the evaluation circuit and the control device are particularly short and therefore not susceptible to interference. In particular, the output signals or output information can be passed directly to a processor (e.g. a microcontroller, FPGA, ASIC, etc.) of the control device. Another advantage is that the control device typically has several electrical lines (power supply lines and / or data lines) leading to consumers, so that the positioning of the evaluation circuit on the control device enables particularly short distances from the at least one antenna line to the evaluation circuit.

It is a further development that the evaluation circuit is integrated into the control device of the household microwave appliance in such a way that it is an independent structural unit (e.g. has its own circuit board or printed circuit board) which is attached to the circuit board or circuit board of the control device, e.g. by soldering connection (s), a slot, etc.

It is a further development that the evaluation circuit is integrated into the control device of the household microwave appliance in such a way that a circuit board of the control device is equipped with the components of the evaluation circuit. ok

It is a further development that the evaluation circuit is functionally integrated in the control device to the extent that a processor of the control device also takes over the evaluation of the antenna line (s). Advantageously, there is then no longer any need for a separate or separately manufactured evaluation circuit.

In one embodiment, the evaluation circuit is connected to the at least one antenna line via at least one conductor track on a circuit board of the control device. This enables a particularly simple, space-saving and robust connection of the evaluation circuit to the at least one conductor track. In particular, an antenna line is led to the circuit board and connected there to the conductor track, e.g. by soldering points, terminals, plugs, etc.

It is an embodiment that the evaluation circuit is connected to the at least one antenna line via a coupling capacitor. This has the advantage that the antenna line is galvanically isolated from the evaluation circuit, but alternating current signals can be transmitted through the coupling capacitor. Through the Koppelkon capacitor a DC voltage separation between the antenna line and off evaluation circuit is achieved. In particular, one connection of the coupling capacitor is electrically connected to at least one antenna line and the other connection is electrically connected to the evaluation circuit. The coupling capacitor can also represent part of the evaluation circuit.

It is an embodiment that the coupling capacitor is a component of a high-pass filter. This has the advantage that the comparatively high-frequency microwave-induced alternating currents (which, for example, can have a frequency in the microwave frequency range) are allowed to pass through to the evaluation circuit, while low-frequency alternating currents, such as those typically used to power a consumer with alternating current ( e.g. with a mains frequency of 50 Hz), cannot be let through. This prevents the measurement signal of the microwave leakage radiation from being disturbed by electrical currents in the antenna lines with lower frequencies, which in turn increases the accuracy of the evaluation. It is a further development that the coupling capacitor forms the high-pass filter together with a particularly grounded ohmic resistor. The resistance can be a component of the evaluation circuit, for example its input resistance.

It is an embodiment that the high-pass filter additionally has a resistor connected to the coupling capacitor, in particular an input resistor, and the coupling capacitor has a capacitance of size C (equation 1):

1

^C 2 p R f _u , where R corresponds to the resistance value of the ohmic resistance and f _u corresponds to a lower limit frequency of the high-pass filter.

This formula results from a complex transfer function T, which shows the ratio of a voltage U2 passed on by the high-pass filter to the voltage L present on the monitored or tapped antenna line (equation 2):

Since only the magnitude of the transfer function (and not its phase position) is of interest here, it follows (Eq. 3):

For the selection and dimensioning of the coupling capacitor C it was assumed that a lower limit frequency f _{u of} the resulting high-pass filter is as high as the signal to be measured at least requires (the measurement signal has a typical microwave frequency of 915 MHz or 2.45 GHz) . The lower limit frequency f _u is set so that the transmitted voltage Ug is only 1 / V2 or approx. 70.7% of the The amplitude of the original signal LL is or the original signal LL is weakened by this factor. It follows from this for the absolute value of the transfer function

This results in the advantageous size of the capacitance value C of the coupling capacitor according to equation 1.

If a sniffer line is connected to the evaluation circuit, it does not need to be galvanically separated from the evaluation circuit by a coupling capacitor. The provision of a high-pass filter can also be dispensed with. Alternatively, the sniffer line is also connected via a coupling capacitor and / or a high-pass filter.

The output or calculation values determined by the evaluation circuit, which represent a measure of the microwave leakage, can be evaluated by the control device. One embodiment is that the household microwave appliance, in particular its control device, is set up to trigger at least one action based on a specific or calculated strength of the alternating current induced by the microwave in at least one antenna line. This has the advantage that it is possible to react automatically to an excessively high leak rate. For example, if a limit value for the calculation values is exceeded, the control device can output a message to a user and / or to a customer service and / or switch off the household microwave device.

A further development is that the calculation values are stored, for example by the control device, in particular in a data memory of the household microwave appliance and / or in an external entity such as a network server. Calculation values can only be saved from the last operating sequence and / or calculation values from several operating sequences. Saving them has the advantage that the calculation values can be evaluated in order to be able to detect a progression of the leak rate over time and thus any drift in a particularly reliable manner. It is a further development that the quality of the delivered devices can be tracked via remote data transmission of the calculation values and a prospective assessment of future service requirements is possible. By reading out the saved data, the customer service can determine whether a shutdown of a microwave device is due to an increased leakage rate in the device, and thus isolate the causes of errors. Aging phenomena in the device / on components (e.g. the magnetron) can also be determined and assessed.

The object is also achieved by a method for operating a household microwave device, in particular as described above, in which electrical useful signals (in particular load currents and / or data signals) to and / or from at least one functional unit via at least one electrical line ("antenna line") of the household microwave device (in particular from and / or to a control device of the device) and from this at least one antenna line microwave-induced alternating currents are tapped (e.g. by means of an evaluation circuit) and evaluated (e.g. by means of the evaluation circuit or the control device).

The method can be designed analogously to the above household microwave device and gives the same advantages.

The properties, features and advantages of this invention described above and the manner in which they are achieved will become clearer and more clearly understood in connection with the following schematic description of an exemplary embodiment which is explained in more detail in connection with the drawings.

1 shows a sectional side view of a household microwave appliance; FIG. 2 shows a plan view of a control device of the household microwave device from FIG. 1 with an evaluation circuit; and

FIG. 3 shows an alternative evaluation circuit for the household microwave device from FIG.

1 shows, as a sectional illustration in a side view, a sketch of a household microwave appliance 1 with a cooking space 2. The cooking space 2 has a cooking space wall or muffle 3, which has a front loading opening that can be closed by a door 4. The household microwave appliance 1 has at least one microwave generator 5 for treating items located in the cooking space 2 (not shown), and possibly also further heating elements such as one or more resistance heating elements (not shown).

There is also an operating device 6 which can have one or more operating elements and / or display devices, e.g. in the form of a touch-sensitive screen. In addition, the household microwave appliance 1 comprises a turntable 7 which is present in the cooking space 2 and which can be rotated by means of a motor 8 arranged outside the cooking space 2. The household microwave appliance 1 or its controllable components 5, 6, 8 can be controlled or actuated by means of a central control device 9 (also referred to as “device control”).

An evaluation circuit 10, which is connected to an antenna line 11, is integrated into the control device 9. The antenna line 11 is that electrical line which leads from the control device 9 to the motor 8 in order to supply the motor 8 with power and / or to transmit data to the motor 8 for its control. The antenna line 11 is also suitable so that alternating currents can be induced in it by microwaves. The evaluation circuit 10 is designed to determine in the Antennenlei device 11 induced alternating currents. The evaluation circuit 10 and the antenna line 11 form a detection device 10, 11 for detecting microwave leakage radiation outside of the cooking chamber 2, in particular in an intermediate space between tween the cooking chamber 2 and an outer housing 12 of the household microwave appliance 1. The antenna line 11 therefore has has a double function, namely firstly for power and / or data transmission between the control device 9 and the motor 8 and secondly as a "sensor line" for detecting microwave leakage radiation.

The antenna line 11 can correspond to the line that would also be used if it were not set up or intended to be used as a sensor line. Alternatively, the antenna line 11 can have at least one section (not shown), the shape and / or position of which is determined by the function of the antenna line 11 as a sensor line. Such an antenna line 11 can, for example, be routed around an opening in the muffle 3 through which a drive shaft of the motor 8 leads to the turntable 7. Additionally or alternatively, the antenna line 11 can, for example have at least one corrugated or meander-shaped section, which, for example, via assembly joints, further openings or the like. the muffle 3 runs.

The antenna line 11 can have a length of at least 800 mm, in particular of at least 1000 mm, in particular of at least 1500 mm, in particular of at least 2000 mm.

The household microwave device 1 can optionally have at least one sniffer line 13, e.g. have a simple wire or a simple cable which is only intended to serve as a sensor line and which is connected to the evaluation circuit and which has no further function. The sniffer line 13 is also connected to the evaluation circuit 10.

2 shows a plan view of the control device 9 with some of the components present on it. Several electrical lines 15 are routed to a circuit board 14 of the control device 9, which are connected at their other ends to functional units of the household microwave device 1 such as electrical consumers and / or sensors (and thus represent antenna lines) and / or are sniffer lines 13. Here one of the electrical lines 15 corresponds to the antenna line 11.

The electrical lines 15 are at connection points 16 such as terminals or the like. connected to the circuit board 14 and go there in corresponding conductor tracks 17 of the circuit board 14 over. In the exemplary embodiment shown, only the antenna line 11 is connected, purely by way of example, to an evaluation circuit 10 arranged on the printed circuit board 14, which in turn is connected to a processor 18, e.g. a microcontroller, ASIC or FPGA, the control device 9 is connected. The evaluation circuit 10 is therefore integrated into the control device 9.

In particular, the evaluation circuit 10 is connected here from the conductor track 17 connected to the antenna line 11 via a coupling capacitor 19, which causes a DC voltage separation between the evaluation circuit 10 and the antenna line 11. The evaluation circuit 10 has, as shown in the enlarged section A, at least one ohmic resistor 20, which is connected on the one hand to the terminal connected to the processor 18 and on the other hand to a predetermined reference potential or ground. The coupling capacitor 19 and the resistor 20 form a high-pass filter 19, 20 for the incoming signal from the antenna line 1 1.

The coupling capacitor 19 here advantageously has a capacitance value C of the size

1

^C 2 p R f _u with R the resistance value of the resistor 20 and f _{u of} a desired lower limit frequency of the high-pass filter 19, 20. The lower limit frequency f _u is chosen so that practically only the microwave-induced voltage components are allowed through.

The Z. B. analog - the output signal of the evaluation circuit 10 is passed to the processor 18 for evaluation (e.g. to an analog input of a microcontroller). However, the evaluation circuit 10 can also have other components or parts (not shown), for example an A / D converter, operational amplifier, etc.

The control device 9 can be set up to trigger at least one action based on a strength of the microwave-induced alternating current in the antenna line 11, represented by the output signal of the evaluation circuit 10, e.g. to reduce the power of the microwave generator 5, switch off the microwave generator 5, issue a message to the user and / or customer service, etc.

This is the case, for example, when leakage sources form or enlarge in or on the muffle 3. The microwaves emerging from the muffle 3 as leakage radiation induce an alternating current in the antenna line 11, which is picked up via the high-pass filter 19, 20 and evaluated by the processor 18. The output signals of the evaluation circuit 10 or a part thereof or values derived therefrom can be stored, for example in order to use them as history data for improved detection of sources of leakage.

3 shows an evaluation circuit 21 which is an alternative to the evaluation circuit 10. The alternative evaluation circuit 10 also has a filter function, but now with an LC filter provided.

Instead of the ohmic resistance 20 shown in FIG. 2, a first coil 22 with an inductance value L1 and an anode side of a diode 23 are connected to the coupling capacitor 19 via a common node. The other connection of the first coil 22 is connected to ground, while the cathode connection of the diode 23 is connected via a further node to a second capacitor 24 with a capacitance value C2 and to a second coil 25 with an inductance value L2. The other terminal of the second capacitor 24 is connected to ground, while the other terminal of the second coil 25 is connected to the processor 18.

Of course, the present invention is not limited to the game Ausführungsbei shown.

Thus, several antenna lines 11 and / or at least one sniffer line can be connected to an evaluation circuit 10 or several evaluation circuits 10.

In general, "a", "an" etc. can be understood to mean a singular or plural, in particular in the sense of "at least one" or "one or more" etc., as long as this is not explicitly excluded, e.g. by the expression "exactly one" etc.

A number can also include exactly the specified number as well as a customary tolerance range, as long as this is not explicitly excluded. List of reference symbols

1 household microwave oven

2 cooking space

3 muffle

4 door

5 microwave generator

6 Control device

7 turntables

8 engine

9 Control device

10 Evaluation circuit

11 antenna cable

12 housing

13 Sniffer line

14 PCB

15 Electrical cable

16 connection point

17 track

18 processor

19 coupling capacitor

20 resistance

21 Evaluation circuit

22 First bobbin

23 diode

24 Second capacitor

25 Second bobbin

A neckline

C capacity value

C2 capacity value

R resistance value

L1 inductance value

L2 inductance value

Claims

1. Household microwave appliance (1), having a cooking chamber (2) and at least one detection device (10, 11; 21, 11) for detecting microwave leakage radiation outside the cooking chamber (2), wherein

the detection device (10, 11; 21, 11) has at least one antenna line (11) in which alternating currents can be induced by microwaves, and an evaluation circuit (10; 21) connected to the at least one antenna line (11) which is used to determine in the at least one antenna line (11) induced alternating currents is formed, and wherein the at least one antenna line (11) has at least one further function.

2. Household microwave appliance (1) according to claim 1, wherein the at least one white direct function

a power supply function for supplying at least one electrical load (8) of the household microwave device (1) with electrical energy,

a data transfer function and / or

a mechanical function

includes.

3. Household microwave appliance (1) according to claim 2, wherein the at least one electrical consumer

a heating element,

a light generating device,

a motor (8),

a power supply device and / or

an electronics

includes.

4. Household microwave device (1) according to one of claims 2 or 3, wherein at least one antenna line min least one data transmission function on has and is connected to at least one functional unit of the device, in particular a sensor, which does not represent an electrical consumer.

5. Household microwave appliance (1) according to one of the preceding claims, where at least one antenna line (11) has at least one section, the shape and / or position of which is determined by the function of the antenna line (11) for detecting the microwave leakage radiation.

6. Household microwave appliance (1) according to one of the preceding claims, where at least one antenna line (11) has a length of at least 800 mm, in particular of at least 1000 mm, in particular of at least 1500 mm, in particular of at least 2000 mm.

7. Household microwave appliance (1) according to any one of the preceding claims, where in the microwave detection device (10, 11; 21, 11) additionally at least one sniffer line (13) in which alternating currents can be induced by microwaves, which with the Evaluation circuit (10; 21) is connected and which has no further function.

8. Household microwave device (1) according to one of the preceding claims, where in the evaluation circuit (10; 21) is integrated into a control device (9) of the household microwave device (1).

9. Household microwave appliance (1) according to claim 8, wherein the evaluation circuit (10; 21) via at least one conductor track (17) of a circuit board (14) of the control device (9) is connected to the at least one antenna line (11).

10. Household microwave appliance (1) according to one of claims 8 or 9, wherein the evaluation circuit (10; 21) is connected via a coupling capacitor (19) to the at least one antenna line (11) and the coupling capacitor (19) ei ne component of a high pass filter (19, 20; 19, 22-25).

11. Household microwave appliance (1) according to claim 10, wherein the high-pass filter (19, 20) additionally has an ohmic Wi- connected to the coupling capacitor (19) the stand (20) and the coupling capacitor (19) has a capacitance value C of the size

1

^C 2 7G - R - fu where R is the resistance value of the ohmic resistor (20) and f _{u has} a lower limit frequency of the high-pass filter (19, 20).

12. Household microwave appliance (1) according to one of the preceding claims, wherein the household microwave appliance (1) is set up, based on a

Strength of the microwave-induced alternating current in at least one antenna line (11) to trigger at least one action.

13. A method for operating a household microwave device (1) according to any one of the preceding claims, wherein electrical useful signals to and / or from at least one functional unit (8) of the household microwave device (1) are transmitted via at least one antenna line (11) and from this at least one antenna line (11) microwave-induced alternating currents are tapped and evaluated.