CN113853832A

CN113853832A - Domestic microwave device with detection means for detecting microwave leakage radiation

Info

Publication number: CN113853832A
Application number: CN202080040011.6A
Authority: CN
Inventors: C·伯特歇尔; A·凯泽; M·库赫勒
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2019-05-30
Filing date: 2020-05-27
Publication date: 2021-12-28
Also published as: DE102019207978A1; EP3977817B1; WO2020239830A1; EP3977817A1

Abstract

The invention relates to a domestic microwave device (1) having a cooking chamber (2) and at least one detection device (10, 11) for detecting microwave leakage radiation outside the cooking chamber (2), wherein the detection device (10, 11) has: at least one antenna line (11) in which an alternating current is induced by microwave energy; and an evaluation circuit (10) which is connected to the at least one antenna line (11) and is designed to determine an alternating current 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 is particularly advantageously applicable to microwaveable ovens and stand-alone microwave ovens.

Description

Domestic microwave device with detection means for detecting microwave leakage radiation

Technical Field

The invention relates to a domestic microwave device having a cooking chamber and at least one detection device for detecting microwave leakage radiation outside the cooking chamber, wherein the detection device has: at least one antenna line in which an alternating current can be induced by microwaves; and an evaluation circuit connected to the at least one antenna line, the evaluation circuit being configured to determine an alternating current induced in the at least one antenna line. The invention also relates to a method for operating a domestic microwave appliance. The invention can be used particularly advantageously in ovens with microwave function and in stand-alone microwave ovens.

Background

EP 2152047 a1 discloses a safety device for detecting leakage radiation in a cooking appliance with microwave function and a cooking appliance with such a safety device. The safety device comprises at least one microwave sensor comprising a detector in which an alternating current can be induced by the leakage radiation or which is adapted to intercept an alternating current induced by the leakage radiation in another object. The sensor further comprises a fuse through which the alternating current is conducted. Finally, the safety device comprises a device adapted to switch off the microwave source of the cooking apparatus upon triggering the safety device.

EP 2148553 a1 discloses a method for monitoring microwave leakage. In the cooking device, the microwave leakage radiation escaping from the cooking chamber is detected by means of a microwave sensor device and its time profile is stored. The subsequent evaluation of the stored microwave radiation values may comprise, inter alia: a prediction of a future time profile of the detected microwave radiation; and early signaling of the situation in which the predicted-based profile is expected to exceed a predetermined threshold. A corresponding device for monitoring microwave leakage and a cooking appliance equipped with such a device are also disclosed.

DE 2029559 a1 discloses a safety device for preventing radiation from escaping from a microwave apparatus, in which at least one microwave-responsive gas tube is used, which is arranged in the vicinity of a possible radiation exit region and is electrically connected to a control circuit of a controlled semiconductor diode, which is itself in the feed circuit of a relay, the excitation of which triggers the disconnection of the electrical feed circuit of the microwave generator.

DE 19537755 a1 discloses a microwave oven, in particular for laboratories, with a heating chamber surrounded by a housing, into which microwave energy is coupled and which can be accessed through a closable access opening. The microwave sensor is arranged in the region of the gap of the housing from the heating chamber in such a way that, when microwave radiation exceeding a specific value enters and/or passes through the gap, the sensor activates the emission of an alarm signal or switches off the microwave application to the heating chamber.

Disclosure of Invention

The object of the present invention is to at least partially overcome the drawbacks of the prior art and in particular to provide a better possibility to identify the leakage of microwaves escaping from the cooking chamber 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 figures.

This object is achieved by a domestic microwave appliance having a cooking chamber and at least one detection device for detecting microwave leakage radiation outside the cooking chamber, wherein,

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

at least one antenna line has at least one further function.

Such a domestic microwave device has the advantage that no separate wires are required to detect microwave leakage. This in turn advantageously achieves a construction which is particularly cost-effective. Furthermore, the antenna line can also have a long length and be laid in a multiplicity of ways in domestic microwave appliances. The advantage is thereby achieved that a large area of the domestic microwave appliance outside the cooking chamber can be monitored with respect to microwave leakage by means of the antenna circuit, whereby the number of detection devices and/or components thereof can be reduced compared to microwave detection devices which only measure point by point. A particularly reliable and cost-effective construction is thus achieved. Another advantage is that the evaluation circuit can be arranged remote from the leaking radiation source in an area of the domestic microwave device that is not subjected to too much thermal, chemical and/or electromagnetic stress. The antenna line, on the other hand, is significantly more resistant and can also pass through regions that are exposed to thermal and chemical stresses (e.g., hot and/or humid). Yet another advantage is that microwave leaks can be identified with a high degree of sensitivity. This also makes it possible to detect an imminent serious microwave leakage in the installation early on. This in turn reduces the potential risk to the user and the after-market staff. Furthermore, early detection of microwave leakage enables after-market service to be performed at such an early point in time that the leaking radiation source can be sealed and the excellent functionality of the apparatus can be fully re-established without component failure. It is thus possible to detect leakage radiation sources early, for example, due to changes in the device, for example, due to component warpage (gap opening) or corrosion of the metal wall (rust holes in the cooking chamber wall), or due to oxidation or also to an increase in the transition resistance due to corrosion (deteriorated electrical contact of the electrical contact foil or sealing braid at the waveguide-muffle transition or at the heating body flange, for example) and to correct them by after-sales service. For example, a malfunction of the microwave generator, such as a fluctuation in power consumption, may be caused by a leakage of microwaves, with the result that both the inverter and the magnetron may be damaged by overload. This also saves the after-sales service staff time in troubleshooting and the after-sales service staff can immediately bring the component to be replaced to the customer if necessary.

The domestic microwave appliance may be a cooking appliance with microwave functionality, in particular an oven with additional microwave functionality, a stand-alone microwave appliance or a microwave appliance with additional IR heating elements such as resistive heating elements, IR radiators or the like.

Household microwave appliances typically have at least one microwave generator, such as a semiconductor-based microwave generator or a magnetron, in order to generate microwaves, with the aid of which objects present in the cooking chamber are treated or loaded. The microwave frequency may be, for example, in the range of 915 MHz or 2.45 GHz. The microwave generator may feed microwaves into the cooking chamber directly or through a microwave guide. Furthermore, there may be means for distributing microwaves in the cooking chamber, such as, in particular, a rotatable feed antenna, a mode stirrer, a wobble oscillator, etc. The generation and introduction of microwaves into a cooking chamber is known in principle and is therefore not explained further here.

Microwave detection devices are used to detect microwave leakage radiation outside the cooking chamber, in particular microwave leakage radiation of household microwave appliances in the region between the cooking chamber wall (also referred to as "muffle" in the following) and the outer housing, but also in the door slot, etc.

The antenna line is an electrically conductive, in particular metallic line, such as a conductor line, a wire, a cable or the like, into which an alternating current is induced by means of microwave energy generated by a microwave generator.

The evaluation circuit is provided, in particular, to determine the intensity of the microwave induced current induced in the at least one antenna line, which microwave induced current is a measure for the intensity of the leakage or the leakage rate. The evaluation circuit can have one or more electrical and/or electronic components and/or functional units such as capacitors, resistors, processors (e.g. microcontrollers, ASICs, FPGAs), rectifiers, a/D converters, etc.

In one embodiment, the evaluation circuit can be connected to exactly one antenna line and thus evaluate only this antenna line or determine the intensity of the microwave induced currents induced in this antenna line. An alternative embodiment is that the evaluation circuit can be connected to a plurality of antenna lines. In this case, a plurality of antenna lines may be collectively evaluated by the evaluation circuit. The joint evaluation makes it possible to provide a particularly simple and inexpensive detection device. This also makes it possible to additionally enlarge the covered or detectable detection area, so that the evaluation unit can also respond earlier if a leak is likely to occur. In one embodiment, a plurality of antenna lines can be electrically combined and connected to the evaluation circuit at a common node. The multiple antenna line alternatives can be evaluated separately, for example temporally separately or in parallel, by means of the same evaluation circuit. The separate evaluation enables an improved localization of the leaking radiation source.

The domestic microwave device may alternatively have a plurality of evaluation circuits, for example connected to one respective antenna line. These evaluation circuits may be distributed over the domestic microwave appliance.

In an embodiment, the at least one antenna line at least partially has or performs at least one further function. The electrical lines already present for other purposes can therefore be used in particular additionally as antenna lines. A line with at least one further function is therefore already present in the device when it is not used to detect microwave leakage.

In one embodiment, the at least one further function comprises a power supply function and/or a data transmission function for supplying electrical energy to at least one consumer of the domestic microwave appliance. In other words, the at least one antenna line is a power supply line and/or a data transmission line for the at least one consumer. The ("load") current for operating the consumer may be a direct current or an alternating current. These antenna lines have the advantage that they are typically of identical design over their length and/or have a defined, in particular low, resistance. This in turn makes it possible to identify or evaluate the alternating current induced by the microwaves particularly accurately and reliably. Another advantage is that these antenna lines typically interconnect functional units in spatial areas of the domestic microwave appliance where the thermal and/or chemical and/or electromagnetic load is small. The evaluation circuit can therefore be arranged in these regions without matching costs or with only a small matching cost with the end sections of the antenna lines.

In principle, however, it is also possible to use other electrically conductive parts of the domestic microwave appliance, which for example perform a mechanical function, as antenna lines, in particular very long parts, such as struts, retaining wires, etc. In this case, it may be necessary to extend the component by means of an additional line section in the form of, for example, a wire toward the evaluation circuit, so that the evaluation circuit can be installed in a space region with a low thermal and/or chemical load and/or in order to be able to make an electrical connection to the evaluation circuit. Additional line sections may be soldered to the electrically conductive member, etc.

In one embodiment, the at least one consumer comprises a heating element, a light generating device, a motor, a power supply device and/or an electronic device (e.g., a control circuit board), etc. The heating element may for example be a resistive heating element for heating a cooking chamber or an evaporator. The light generating device may be or have a lamp or other lighting device, for example, for illuminating a cooking chamber, operating elements or decorative elements. The motor may for example be a motor for moving a rotating antenna, a barbecue stick, a ventilator, a hood (e.g. a smoke hood), a turntable, a cooking chamber door, a pump, etc. The at least one consumer is not limited to this in principle and can be any other consumer, such as a control panel or a component of a control panel, a camera, a communication module (for example a WLAN module or an ethernet module), etc.

In one embodiment, at least one antenna line has at least one data transmission function and is connected to at least one functional unit of the device that is not an electrical consumer, for example to a sensor, reed contact or other magnetic switch. This is the case, for example, when the functional unit which consumes no power is a sensor, for example a temperature sensor, in particular a temperature detection element. However, sensors exist which are consumers, for example oxygen sensors in the form of lambda probes, which have a heating element. If the functional unit of the non-consumer is a reed contact, this reed contact can only switch the signal level in one variant (in which, for example, the microcontroller evaluates the switching state), and in other variants, for example, switches the excitation current of the relay coil. The cable run of the two reed contacts is a suitable antenna line.

The electrical line may also be arranged or used as an antenna line for both supplying power and transmitting data, for example by modulating a supply signal with a data signal. The consumers can in principle be connected both to dedicated power supply lines and to dedicated data lines, one or more of which can be used as antenna lines.

In one embodiment, 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 microwave leakage radiation. This section therefore does not contribute to performing further functions of the antenna line or may even (even if typically only slightly) have a negative effect on this. An advantage of such a section is that it is shaped and/or laid for improved detection of microwave leakage radiation and thus enables particularly reliable detection of microwave leakage radiation. The sections may be placed, for example, through or around an open area of the cooking chamber wall. The ohmic resistance of the section is enlarged by the increase in length, but this has only a negligibly small or virtually no effect on its current-conducting function and/or data transmission function. The sections may also be shaped in a coiled manner (for example in a meandering manner).

One embodiment provides that the at least one antenna line has at least one length of at least 800 mm, in particular at least 1000 mm, in particular at least 1500 mm, in particular at least 2000 mm. Such a long length yields the advantage that as much/large an area as possible in the interior of the housing of the domestic microwave device can be covered with the antenna line and thus a locally distributed source of leakage radiation can be sensed or detected with a small number of antenna lines.

Since the leakage radiation sources not only locally but often also not strongly radiate over time (for example, due to the temporally different pattern distribution in the cooking chamber as a result of the movement of the supply line, the pattern stirrer and/or the rotary disk), it is advantageous if the antenna circuit has the property of being locally and possibly also temporally integrated. The superposition of the different incident microwave signals then produces a sum signal which is applied to the microwave sensor. The longer the antenna line, the more pronounced this superposition.

In one embodiment, the microwave detection device additionally has at least one electrically conductive line in which an alternating current can be induced by microwaves, which line is connected to the evaluation circuit and has no further signal-conducting (i.e., does not conduct current and/or transmit data) function, in particular no further function. Such a line may be referred to hereinafter as a "sniffed line". Sniffing lines are therefore laid only for the purpose of detecting microwave-based induction. The domestic microwave appliance can thus be constructed such that the evaluation circuit is connected to at least one antenna line (which also performs at least one further function) and at least one sniffing line (without a dedicated further function). The provision of a sniffing line has the advantage that it can be laid down in the device particularly flexibly, for example because it is functionally connected at one end to the evaluation circuit, but the other end is a freely positionable end. The sniffing line can in principle be constructed and/or connected similarly to the antenna line. As the sniffing line, for example, a metal wire, a cable, a conductor line mounted on a substrate, or the like can be used.

In an embodiment, the at least one evaluation circuit is a separate component of the domestic microwave appliance, is arranged separately from the control device and is connected to the control device via at least one signal line. The advantage is thereby achieved that the at least one evaluation circuit can be positioned particularly flexibly in the domestic microwave device. The evaluation circuit may in particular provide information about the intensity of the microwave induced alternating current as an output signal or output information. The output signal or output information can exist in analog or digital form. The output signal or the output information can be used by the control device to evaluate whether at least one behavior associated with the intensity of the leak rate should be triggered, as will be explained more precisely below.

In one embodiment, the evaluation circuit is integrated into a control device of the domestic microwave appliance. This provides the advantage that the evaluation circuit is installed in a space area which is particularly well suited or provided for the installation of electrical and/or electronic components. This is particularly advantageous if the control device is installed in a particularly protected compartment, cubicle or cubicle, which is thermally insulated and/or ventilated for cooling the evaluation unit, for example. A further advantage is that the signal path between the evaluation circuit and the control device is particularly short and therefore susceptible to faults. The output signal or output information can in particular be fed directly to a processor (for example microcontroller, FPGA, ASIC, etc.) of the control device. A further advantage is that a plurality of lines (power supply lines and/or data lines) typically leave the control device to the consumers, so that the positioning of the evaluation circuit at the control device enables a particularly short path from the at least one antenna line to the evaluation circuit.

In one embodiment, the evaluation circuit is integrated into the control device of the domestic microwave appliance in such a way that it is a separate component (for example, having its own printed circuit board or circuit board) which is fastened to the circuit board or printed circuit board of the control device, for example, by means of a soldered connection, a socket or the like.

In an embodiment, the evaluation circuit is integrated into the control device of the domestic microwave appliance in such a way that the circuit board of the control device is equipped with the components of the evaluation circuit.

In an embodiment, the evaluation circuit is functionally integrated into the control device in such a way that the processor of the control device also undertakes the evaluation of the one or more antenna lines. Advantageously, then, no separate or separately produced evaluation circuit is required.

In one embodiment, the evaluation circuit is connected to the at least one antenna line via at least one conductor line of a circuit board of the control device. A particularly simple, space-saving and robust connection of the evaluation circuit to the at least one conductor track is thus achieved. The antenna lines are in particular routed to the printed circuit board and are connected there to conductor lines, for example, by soldering points, terminals (Klemmen), plugs, etc.

In one embodiment, the evaluation circuit is connected to the at least one antenna line via a coupling capacitor. This achieves the advantage that the antenna line is galvanically separated from the evaluation circuit, but the alternating current signal can then be transmitted via the coupling capacitor. A dc voltage separation between the antenna line and the evaluation circuit is thus achieved by the coupling capacitor. One terminal of the coupling capacitor is electrically connected to the at least one antenna line and the other terminal is electrically connected to the evaluation circuit. The coupling capacitor may also be part of the evaluation circuit.

In one embodiment, the coupling capacitor is a component of the high-pass filter. The advantage is thus achieved that a relatively high-frequency microwave-induced alternating current, which may for example have a frequency in the microwave frequency range, is allowed to pass through to the evaluation circuit, whereas for example a low-frequency alternating current, which is typically used with an alternating current (for example with a supply frequency of 50 Hz) for supplying power to the consumers, cannot be allowed to pass through. This prevents interference with the measurement signal of the microwave leakage radiation by currents having a low frequency in the antenna line, which in turn increases the evaluation accuracy.

In an embodiment, the coupling capacitor and the ohmic resistor, which is in particular connected to ground, together form a high-pass filter. The resistance may be a component of the evaluation circuit, for example its input resistance.

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

wherein R corresponds to the resistance value of the ohmic resistor and

corresponding to the lower frequency limit of the high pass filter.

This formula consists of a complex transfer function

It follows that the transfer function describes the voltage conveyed by the high-pass filter

With voltage applied to the monitored or tapped antenna line

Ratio of (equation 2):

。

since here only the value of the transfer function (and not its phase) is of interest, this yields (equation 3):

。

for the selection and dimensioning of C of the coupling capacitor, it is assumed that the lower frequency limit of the generated high-pass

At least as high as required for the signal to be measured (the measurement signal has a typical microwave frequency of 915 MHz or 2.45 GHz). Thus, the lower limit of the frequency is set in this way

So that the transmitted voltage

Only the original signal

Of amplitude of

Or about 70.7%, or the original signal

With this factor decreasing in magnitude. This gives the value of the transfer function:

。

an advantageous dimensioning of the capacitance value C of the coupling capacitor according to equation 1 is thus obtained.

If the sniffing line is connected to the evaluation circuit, this sniffing line does not need to be galvanically separated from the evaluation circuit by a coupling capacitor. The high pass filter setting can also be eliminated. Alternatively, the sniffing line can also be connected via a coupling capacitor and/or a high-pass filter.

The output or calculated value determined by the evaluation circuit, which is a measure for the microwave leakage, can be evaluated by the control device. In one embodiment, the domestic microwave appliance, in particular the control device thereof, is provided for triggering at least one action on the basis of a specific or calculated intensity of the alternating current induced by the microwaves in the at least one antenna line. The advantage is thus achieved that an automatic response to an excessively high leakage rate is possible. The control device can, for example, notify the user and/or the after-sales service and/or switch off the domestic microwave appliance when the limit value of the calculated value is exceeded.

An embodiment provides that the calculated values are stored, for example, by the control device, in particular in a data memory of the domestic microwave device and/or in an external control entity such as a network server. Only the calculated value of the last operational flow and/or the calculated values of a plurality of operational flows may be stored. The advantage obtained by their storage is that the calculated values can be evaluated in order to be able to detect the leakage rate profile over time and thus possible drift in a particularly reliable manner.

An embodiment is that the remote data transmission of the calculated values allows the quality level of the delivered device to be tracked and the future service requirements to be predictively assessed. After-service personnel can confirm by reading the stored data whether the switching off of the microwave device can be attributed to an increased leak rate in the device and thus define the cause of the fault. It is also possible to confirm and estimate the aging phenomenon in/at the equipment (e.g., magnetron).

The object is also achieved by a method for operating a domestic microwave appliance, in particular as described above, in which an electrical useful signal (in particular a load current and/or a data signal) is transmitted to and/or from at least one functional unit of the domestic microwave appliance via at least one electrical line ("antenna line") (in particular from and/or to a control device of the appliance) and the microwave-induced alternating current is intercepted (for example by means of an evaluation circuit) and evaluated (for example by means of an evaluation circuit or a control device) from this at least one antenna line.

The method can be constructed similarly to the above-described domestic microwave device and achieves the same advantages.

Drawings

The above features, characteristics and advantages of the present invention and the manner and method of how to achieve them will become more apparent and more readily understood from the following schematic description of an embodiment, which is illustrated in more detail in connection with the accompanying drawings:

fig. 1 shows a domestic microwave device as a sectional view in a side view;

fig. 2 shows a control device of the domestic microwave appliance of fig. 1 with an evaluation circuit in a top view; and is

Fig. 3 shows an alternative evaluation circuit for the domestic microwave device of fig. 1.

Detailed Description

Fig. 1 shows a schematic representation of a domestic microwave appliance 1 with a cooking chamber 2 in a side view as a sectional illustration. The cooking chamber 2 is surrounded by a cooking chamber wall or muffle 3, which has a front loading opening that can be closed with a door 4. The domestic microwave appliance 1 has at least one microwave generator 5 for treating objects (not shown) in the cooking chamber 2, and optionally also further heating elements, such as one or more resistance heating elements (not shown).

Furthermore, an operating device 6 is present, which may have one or more operating elements and/or a display device, for example in the form of a touch-sensitive screen. Furthermore, the household microwave device 1 comprises a turntable 7 present in the cooking chamber 2, which is rotatable by means of a motor 8 arranged outside the cooking chamber 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 "appliance control device").

An evaluation circuit 10 is integrated into the control device 9, which evaluation circuit is connected to the antenna line 11. The antenna line 11 is a line which leads from the control device 9 to the motor 8 in order to supply the motor 8 with current and/or to transmit data to the motor 8 for controlling the latter. The antenna line 11 is also adapted to be able to induce an alternating current in the antenna line by means of microwaves. The evaluation circuit 10 is designed to determine the alternating current induced in the antenna line 11. The evaluation circuit 10 and the antenna line 11 form detection means 10, 11 for detecting microwave leakage radiation outside the cooking chamber 2, in particular in a gap between the cooking chamber 2 and an outer housing 12 of the domestic microwave device 1. The antenna line 11 thus has a dual function, namely firstly, for transmitting current and/or data between the control device 9 and the motor 8 and secondly, as a "sensor line" for detecting microwave leakage radiation.

The antenna line 11 may correspond to a line to be used even if not provided or specified for use as a sensor line. The antenna line 11 may alternatively have at least one section (not shown) whose shape and/or position is determined as a sensor line by the function of the antenna line 11. Such an antenna line 11 can thus be guided, for example, around a cutout in the muffle 3, through which the drive shaft of the motor 8 leads to the rotary disk 7. The antenna line 11 may alternatively or additionally have, for example, at least one undulated or meandering section which extends, for example, over a mounting joint, a further opening or the like of the muffle 3.

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

The domestic microwave device 1 can optionally correspond to a device having at least one sniffing line 13, for example a single metal wire or a single cable, which is provided only for use as a sensor line and is connected to the evaluation circuit and has no further function. The sniffing line 13 is likewise connected to the evaluation circuit 10.

Fig. 2 shows a schematic representation of the control device 9 with some components present on the control device in a top view. A plurality of wires 15 lead to the circuit board 14 of the control device 9, which wires are connected at their other ends with functional units of the domestic microwave device 1, such as consumers and/or sensors (and are thus antenna lines) and/or sniffing lines 13. One of the wires 15 corresponds here to the antenna line 11.

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

The evaluation circuit 10 is connected here in particular by a conductor line 17 connected to the antenna line 11 via a coupling capacitor 19, which facilitates a dc voltage separation between the evaluation circuit 10 and the antenna line 11.

As shown in the enlarged section a, the evaluation circuit 10 has at least one ohmic resistor 20, which is connected on the one hand to a terminal connected to the processor 18 and on the other hand to a predetermined reference potential or ground line. The coupling capacitor 19 and the resistor 10 form a high-

pass filter

19, 20 for the signal from the antenna line 11.

The coupling capacitor 19 is advantageously of a size of

Wherein R is the power of resistor 20Resistance value and

is the desired lower frequency limit of the high pass filters 19, 20. Thus selecting the lower frequency limit

So that practically only the microwave induced voltage part is allowed to pass.

The output signal of the evaluation circuit 10, for example, analog, is conducted for evaluation to a processor 18 (for example, to an analog input of a microcontroller). The evaluation circuit 10 may also have further components or components (not shown), such as an a/D converter, an operational amplifier, etc.

The control device 9 can be provided for triggering at least one action, for example a reduction in the power of the microwave generator 5, a switching off of the microwave generator 5, an indication to a user and/or after-sales service personnel, etc., on the basis of the intensity of the alternating current induced in the antenna line 11, which is represented by the output signal of the evaluation circuit 10.

This is the case, for example, when a source of leakage in or at the muffle 3 develops or expands. The microwaves escaping from the muffle 3 as leakage radiation induce an alternating current in the antenna line 11, which is intercepted by high-

pass filters

19, 20 and evaluated by the processor 18.

The output signal or a part of the output signal of the evaluation circuit 10 or a value derived from the output signal can be stored, for example, in order to use them as historical data for improving the identification of the leakage source.

Fig. 3 shows an evaluation circuit 21 as an alternative to the evaluation circuit 10. The alternative evaluation circuit 21 likewise has a filter function, but now with the LC filter provided.

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

The invention is of course not limited to the embodiments shown.

A plurality of antenna lines 11 and/or at least one sniffing line can therefore be connected to one evaluation circuit 10 or to a plurality of evaluation circuits 10.

"a", "an", etc. can generally be understood in the singular or in the plural, especially in the sense of "at least one" or "one or more", etc., as long as this is not explicitly excluded, for example by the wording "exactly one", etc.

The quantitative indication may also include exactly the stated amount and the remaining tolerance ranges, as long as this is not explicitly excluded.

List of reference numerals

1 household microwave device

2 cooking chamber

3 muffle furnace

4 door

5 microwave generator

6 operating device

7 rotating disc

8 Motor

9 control device

10 evaluation circuit

11 antenna line

12 casing

13 sniffing line

14 circuit board

15 electric wire

16 connection point

17 conductor line

18 processor

19 coupling capacitor

20 resistance

21 evaluation circuit

22 first coil

23 diode

24 second capacitor

25 second coil

Fragment A

C capacitance value

C2 capacitance value

R resistance value

L1 induction value

L2 sense value.

Claims

1. Domestic microwave device (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 an alternating current is induced by microwave energy; and an evaluation circuit (10; 21) connected to the at least one antenna line (11), which evaluation circuit is designed to determine an alternating current induced in the at least one antenna line (11), and wherein,

-at least one antenna line (11) has at least one further function.

2. A domestic microwave device (1) according to claim 1, wherein the at least one further function comprises:

-a power supply function for supplying electrical energy to at least one electrical consumer (8) of the domestic microwave device (1),

-data transfer function and/or

-a mechanical function.

3. A domestic microwave device (1) according to claim 2, wherein the at least one consumer comprises:

-a heating element for heating the substrate,

-a light generating means for generating light,

-a motor (8),

-a power supply device and/or

-an electronic device.

4. Household microwave device (1) according to any one of claims 2 or 3, wherein said at least one antenna line has at least one data transmission function and is connected to a functional unit, in particular a sensor, of at least one non-consumer of said device.

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

6. The domestic microwave device (1) according to any one of the preceding claims, wherein the at least one antenna line (11) has a length of at least 800 mm, in particular at least 1000 mm, in particular at least 1500 mm, in particular at least 2000 mm.

7. Household microwave device (1) according to any one of the preceding claims, wherein the microwave detection means (10, 11; 21, 11) additionally have at least one sniffing line (13) in which an alternating current is induced by the microwave energy, which sniffing line is connected to the evaluation circuit (10; 21) and has no further function.

8. The domestic microwave device (1) according to any one of the preceding claims, wherein the evaluation circuit (10; 21) is integrated into a control means (9) of the domestic microwave device (1).

9. A household microwave device (1) according to claim 8, wherein said evaluation circuit (10; 21) is connected to said at least one antenna line (11) through at least one conductor line (17) of a circuit board (14) of said control means (9).

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

11. Household microwave device (1) according to claim 10, wherein said high pass filter (19, 20) additionally has an ohmic resistance (20) connected to said coupling capacitor (19) and said coupling capacitor (19) has a size of

Wherein R is the resistance value of the ohmic resistor (20) and

is the lower frequency limit of the high pass filter (19, 20).

12. The domestic microwave device (1) according to any one of the preceding claims, wherein the domestic microwave device (1) is arranged for triggering at least one action based on the intensity of an alternating current induced by microwaves in the at least one antenna line (11).

13. Method for operating a domestic microwave device (1) according to one of the preceding claims, wherein an electrical useful signal is transmitted to and/or from at least one functional unit (8) of the domestic microwave device (1) via the at least one antenna line (11), and the microwave-induced alternating current is intercepted and evaluated by the at least one antenna line (11).