EP2027749B1

EP2027749B1 - Household appliance

Info

Publication number: EP2027749B1
Application number: EP06806050.8A
Authority: EP
Inventors: Sergey Argudyaev; Sergey Leonenkov; Claudio Cenedese
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2006-04-12
Filing date: 2006-10-05
Publication date: 2017-08-16
Anticipated expiration: 2026-10-05
Also published as: WO2007115587A1; WO2007115588A1; EP2027749A1; CN101356851B; RU2395853C2; RU2006112158A; CN101356851A

Description

Technical field

The present invention relates generally to a household appliance, and in particular to a household appliance with an integrated speaker.

Technical background

There is a common trend to enrich the user interfaces of household appliances by introducing multimedia functions. Such functions may include music playback, FM radio, the announcement of voice messages, etc.
An example of a household appliance with music playback functionality is disclosed in the document US20040164073 . Namely, US20040164073 discloses a microwave oven an audio player and a speaker to output sound signals reproduced by the audio player. Further, a household appliance with radio is disclosed in the document US2004004807 , wherein a microwave oven comprises a radio module and a speaker. WO2004083751 further discloses a refrigerator comprising a speaker for allowing a telephone conversation and sending audio messages.
US 2004/0189462 discloses a signalling device for detecting the end-of-operation of a machine or an appliance, and for transmitting a signal representative of the detected end-of-operation to a receiver circuit which is a spatially separated part of the signalling device and converts said signal into an optical, acoustic and/or tactile signal and outputs the same. The signalling device comprises a sensor, which is placed on top of an appliance being monitored and which is preferably an electro-dynamic or piezo-electric transmitter to receive the appliance vibrations and/or noises stemming from the appliance motors, water flow, and/or buzzer, or the like.
WO 00/54548 discloses an electronic apparatus incorporating a loudspeaker, wherein the loudspeaker comprises a bending wave panel member having a user-accessible surface, an electro-acoustic vibration exciter on the panel member to introduce bending wave energy into the panel member in response to an electrical signal applied thereto, and at least one touch sensitive area associated with the said user-accessible surface and responsive to user contact.
US 2004/0133366 discloses a contact sensitive device that includes a member capable of supporting bending waves and a plurality of electrodynamic or piezoelectric sensors mounted on the member for measuring bending wave vibration in the member. At least one of the sensors may also act as an emitting transducer for exciting bending wave vibration in the plate. In this way, the device may act as a combined loudspeaker and contact sensitive device. In this latter case the device comprises a member in which bending waves are generated by an emitting transducer or actuator and the contact. It also discloses a method for partitioning the audio signal and measured signal into two distinct frequency bands so that the contribution of the audio signal to the processed measured signal is suppressed.
US 2005/212777 further discloses a house hold appliance. Some of the appliances of the above documents seem to utilize discrete conventional speakers provided inside the appliance at a dedicated opening in the appliance's exterior casing. However, a conventional loudspeaker placed inside a household appliance has several disadvantages. For example, a conventional loudspeaker usually takes much space inside the appliance (due to the speaker cone), and the existing construction of the appliance has to be changed in order to mount the loudspeaker. Further, if the loudspeaker is closed by the casing of the appliance, the sound volume/quality is limited. On the other hand, if the loudspeaker is opened (special hole in the casing), the impermeability of the casing is impaired.

Summary of the invention

It is an object of the present invention to overcome or at least alleviate these problems, and to provide an improved household appliance with integrated speaker.
This and other objects that will be evident from the following description is achieved by means of a household appliance, according to the appended claims.
According to one aspect of the invention, there is provided a household appliance according to claim 1. This configuration allows for generation of a sound (by applying the first electric signal to the exciter element) and/or detection of a vibration (causing generation of the second electric signal).
When attached to a surface, the magnetostrictive/electrodynamic exciter element transforms electric signals into mechanical energy and moves the surface, creating a small but powerful vibration, and reciprocally. The magnetostrictive exciter element requires a relatively hard and thick panel to reach good sound quality in sound generation mode, whereas the electrodynamic exciter element also can be used for softer and thinner panels, which makes them particularly suitable for use with especially exterior surfaces of a household appliance, which usually are made of metal or plastics or a wood type material. Further, the magnetostrictive and electrodynamic exciter elements do not require a high power output amplifier, whereby sound can be generated with low power consumption.
In one embodiment, the first electric signal is an audio signal, and the surface is adapted to convert the first vibration to a sound. Namely, the audio signal applied to the exciter element causes a corresponding first vibration of the same, which first vibration is transferred to the surface to generate a sound. Thus, the surface and the exciter element forms a flat panel speaker. Such a flat panel speaker provides significantly higher sound pressure level at wider bandwidth than a traditional loudspeaker of similar size. This in combination with the fact that no traditional speaker cone is required means that the speaker configuration according to this embodiment of the invention requires less space within the appliance. Further, since an existing surface of the appliance is used, it is possible to implement the speaker without considerably change the existing construction of the appliance. Also, the exciter element is simple and cheap to install, for example it can simply be glued to the surface at a convenient place. Also, unlike most conventional speakers, especially speakers comprising a paper membrane, the exciter element can usually operate under extreme environmental conditions (e.g. high temperature, humidity, etc.), which is significant for the basic operation of various household appliances.
Here, the frequency range of the exciter element is preferably in the audible audio band, for example between about 200 and 20 000 Hz, for allowing playback of for instance music or voiced speech. Further, the household appliance comprises an audio source or an audio signal receiver, for providing the audio signal. The audio source can for example be a built in radio or audio player, and the audio signal receiver can for example be adapted for wireless transmission of an audio signal from an external source or comprise contacts for allowing physical connection to an external audio player. The household appliance further comprises means for receiving and optionally processing the second electric signal to provide a detection signal representative of the second vibration. Thus, the surface and exciter element can also alternatively be used to detect or measure vibrations and related events, like a microphone. Namely, a second vibration occurring in the surface is transferred to the exciter element, which generates a second electric signal in accordance with the second vibration (i.e. an essentially reverse course of events compared to sound generation discussed above). Here, the exciter element is an electrodynamic exciter element.
The vibration occurring in the surface can originate from an event inside the household appliance, such as excessive load of a laundering machine, or an external event, such as a user "knocking" on the surface. Further, the processing or analysing the signal generated by the electrodynamic exciter element allows estimation of the characteristics of the vibration and its source or reason.
Conveniently, the operation of the household appliance can be affected in accordance with the detection signal. This is achieved by providing means for generating a control signal in accordance with the detection signal for execution of a household appliance operation. For example, if a powerful vibration is detected from within a laundering machine (due to for instance excessive load), a control signal instructing the laundering machine to slow down or halter its operation can be generated. In another example, if a knock by a user on the exterior surface of the household appliance is detected, a control signal instructing the appliance to vocally announce its status (for example by means of the same exciter element and surface used as a speaker) can be generated, which provides improved functionality and usability of the household appliance. Further, the above means can for example be realised by a single central control and processing unit of the household appliance.
In case the above surface and exciter element is used both as a speaker for generating sound and as a microphone for detecting vibrations, the household appliance further comprises means for selectively activating the audio source or audio signal receiver and the means for receiving and optionally processing the second electric signal. Preferably, the above surface is an exterior surface of a casing of the household appliance, to best generate sound to the outside of the household appliance and/or detect a "knock" on the surface by a user. In this case, the exciter element is preferably mounted to the inside of the exterior surface, for sound generation and design purposes. No dedicated opening in the exterior surface of the appliance is required, whereby the impermeability of the surface can be maintained.
The exciter element can for example be mounted to a front, side or top panel of the household appliance. These surfaces are usually large and flat enough to generate sound or pick up vibrations. However, the side and top panels are usually covered by other appliances or furniture, whereby the most preferably place for the exciter element is at the inside the front panel, which usually is not blocked by any other furniture or appliances. Nevertheless, an additional exterior panel covering the surface can be provided without significantly altering the sound generation or vibration detection capability. Such an additional exterior panel is often used in built-in household appliances. The household appliance can further comprise at least one additional exciter element mounted to a surface of the household appliance. The additional exciter element (S) may or may not be of similar type or have similar characteristic as the exciter element mentioned above. Also, the surface may or may not be the same as the surface mentioned above. Placing several exciter elements on a single surface provides for improved sound quality and loudness, whereas placing exciter element on different surfaces provides for stereo or surround sound playback.
The household appliance discussed above can for example be an oven, a microwave oven, a refrigerator, a freezer, a dishwasher, a laundering machine, or a tumbler dryer.

Brief description of the drawings

These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing currently preferred embodiments of the invention.

Fig. 1 schematically illustrates the basic principle of a household appliance with an integrated speaker.
Figs. 2a-2b schematically illustrate in detail a magnetostrictive and electrodynamic exciter element, respectively.
Figs. 3a-3b illustrate various placings for the exciter element on household appliances,
Fig. 4a-4c illustrate various household appliances with additional exciter elements, and
Fig. 5 illustrates the basic principle of a household appliance with an integrated speaker and accelerometer according to the invention.

Detailed description of the invention

Fig. 1 schematically illustrates the basic principle of a household appliance 10 with an integrated speaker according to an embodiment of the invention. The household appliance 10 comprises a surface 12, for example an exterior surface of a casing of the household appliance 10. The surface 12 is preferably a flat surface, such as a top, front, or side panel of the household appliance 10. An exciter element 14 is further mounted to the inside of the surface 12 with a hard mechanical connection. The exciter element 14 can for example be glued to the surface 12. The exciter element is further coupled to an audio source 16a or audio signal receiver 16b via an output amplifier 18. The audio source 16a can for example be a built in radio or audio player, and the audio signal receiver 16b can for example be adapted for wireless transmission of an audio signal from an external source or comprise contacts for allowing physical connection to an external audio player.
Upon operation, an electric audio signal is supplied from the audio source 16a or the audio signal receiver 16b via the amplifier 18, which appropriately amplifies the electric audio signal, to the exciter element 14. When the electric audio signal is applied to the exciter element 14, it generates a vibration in accordance with the applied electric audio signal. The vibration is passed on to the surface 12, which also starts to vibrate. The vibrating surface 12 creates thickenings and rarefactions, i.e. acoustic waves, in the air surrounding the surface 12. Thus, the surface 12 acts as speaker panel and converts the vibration originating from the exciter element 14 to a sound. Optionally, an additional exterior panel 32 can be mounted to the outside of the surface 12 to cover said surface. Such a panel 32 is often used in built-in household appliances and it is usually customized and designed to match surrounding furniture. The panel 32 is mounted to the surface 12 such that, when an electric audio signal is applied to the exciter element 14 and the surface 12 starts to vibrate, the vibration is passed on to the exterior panel 32, which (as the surface 12 above) converts the vibration to a sound. Unlike the case of any conventional speaker, since no dedicated openings in the exterior panel 32 are required to generate a high-quality sound, the appearance and design of a furniture as a whole and of a given household appliance in particular remains unchanged.
The exciter element 14 can for example be a magnetostrictive exciter element. Such an element is known per se, as will be recognized by the skilled person. With reference to fig. 2a, the magnetostrictive exciter element 14 comprises a bar 20 of a material which is capable to vary its own shape and size when exposed to a magnetic field. A coil 22 is further wrapped around the bar 20. When the electric audio signal is supplied to and passed through the coil 22, the coil 22 generates a magnetic field, whereby the size of the bar 20 changes accordingly (i.e. it expands/contracts).
When the bar 20 is attached to a surface, in the case of the invention the surface 12 of a household appliance, the expansion/contraction of the bar 20 is passed on the surface 12, which surface 12 starts to vibrate, whereby a sound can be generated. The response time of the magnetostrictive exciter element 14 fast, in the order of microseconds, and it creates a small but powerful vibration, without requiring a high power output amplifier. These characteristics make the magnetostrictive exciter element particularly suitable for use with an exterior surface of the household appliance which is relatively hard and thick, such as a top panel made of a wood type material.
Alternatively, the exciter element 14 can be an electrodynamic exciter element. With reference to fig. 2b, the electrodynamic exciter element 14 comprises a non-conducting part 24 connected to a massive constant magnet 26 by a flexible fixture 28, usually a hard plane spring. Due to the flexible fixture 28, the part 24 can slightly move in to and out from the magnet 26. A coil 30 is further wrapped around the non-conducting part 24.
When the electric audio signal is supplied to and passed through the coil 30, the coil 30 generates an alternating magnetic field which interacts with the constant magnetic field of the magnet 26. The resulting mechanical force causes the magnet 26 and the part 24 to pull in and push out each other.
When the moving part 24 is attached to a surface, in the case of the invention the surface 12 of a household appliance, the motion of the part 24 is passed on the surface 12. Namely, since the constant magnet 26 is a massive element in comparison to the combined weight of the part 24, the coil 30 and the surface 12 (at the limited area of the attachment of the part 24), the massive magnet 26 has a bigger inertia and almost does not move itself in the space. Contrarily, an amplitude of oscillation of the surface 12 is high enough to emit the acoustic waves. Thus, when the electric audio signal is supplied to the coil 30, the surface 12 starts to vibrate in accordance to the signal, whereby a sound can be generated. The resulting sound pressure level is high at wide audio bandwidth including low frequency and high frequency bands, whereas the electrical power consumption is low. These characteristics make the electrodynamic exciter element suitable for use with various surfaces of the household appliance, such as surfaces made of metal (front and side panels), plastics (front panel), glass (front panel of oven, top cover of cooking surface), or a wood type material (top panel).
The exciter element 14 is preferably placed at a flat area of the surface of the household appliance, generally close to the middle of the surface. In fig. 3a, the household appliance 10 is a refrigerator, the surface 12 is the front panel of the refrigerator, and the exciter element 14 is positioned in the middle of the front panel, on the inside of the panel. Thus, during operation, essentially the whole front panel of the refrigerator serves as a speaker panel. Fig. 3b disclose another exemplary household appliance 10, namely a front loaded washing machine. In fig. 3b, the surface 12 is the top panel of the washing machine, and the exciter element 14 is positioned in the middle of the top panel, on the inside of the panel. As in fig. 3a, during operation, essentially the whole top panel 12 of the washing machine serves as a speaker panel to generate sound. Reference numbers 14' indicates alternative positions of the exciter element at a relatively flat area of the front panel of the washing machine. Other household or domestic appliances or white goods to which the exciter element 14 can be applied include, but is not restricted to, ovens, microwave ovens, freezers, dishwashers, and tumbler dryers.
It should be noted that when an exciter element is mounted to a metal panel, as may be the case in a household appliance according to the invention, the total harmonic distortion when generating sound can be high, resulting in "metallic noise". Actually, better sound can be obtained from wooden, plastic, or glass plates. Nevertheless, in order to suppress such "metallic noise", the metal panel can be covered by a panel of another material, such as the additional exterior panel 32 shown in fig. 1. Alternatively, the metal panel can have some apertures, bends or fixture elements (not shown in drawings) a certain distance far from the exciter element. Both these solutions serve to extend the bandwidth and reduce the total harmonic distortion.
The household appliance 10 can further comprise at least one additional exciter element. The additional exciter element(s) may or may not be of similar type or have similar characteristic as the exciter element mentioned above. Also, the surface may or may not be the same as the surface mentioned above.
In fig. 4a, wherein the household appliance 10 is a refrigerator, an additional exciter element 14b is provided on the front panel 12 together with the first exciter element 14. The additional exciter element 14b is, in the same manner as the first exciter element 14, connected to the amplifier 18 and the audio source 16a/audio signal receiver 16b. The exciter elements 14 and 14b (both attached to the front panel 12) can be of different types or have different characteristics to widen the audio bandwidth emitted by the surface 12.
Stereo sound can be provided by placing two similar exciter elements 14 and 14b on different surfaces 12 and 12b, as shown in fig. 4b for an exemplary washing machine 10. Alternatively, stereo playback can be achieved by positioning two similar exciter elements 14' and 14b', symmetrically far enough one from another on the same surface 12' of the washing machine 10. Furthermore, by introducing several exciter elements of similar or different types and characteristics, mounted to the inside of the same or diverse surface(s), a high-quality surround sound can be generated. Fig. 4c discloses an exemplary refrigerator 10 comprising five exciter elements mounted on the inside of different surfaces. For example, the exciter elements 14 and 14b (attached to the front panel 12) can be of different types or have different characteristics to widen the audio bandwidth emitted by the surface 12. On the other hand, the exciter elements 14c (attached to the top panel 12b), 14d (attached to the left panel 12c), and 14e (attached to the right panel 12d) can be of the same type to create a surround sound.
Fig. 5 schematically illustrates the basic principle of a household appliance 10 according to the invention. In the embodiment shown in fig. 5, the exciter element and surface can be used not only for generation of sound, but also for measurement or detection purposes.
The household appliance 10 in fig. 5 is similar to that of fig. 1, and only pertinent difference will be described in detail. As above, the household appliance 10 comprises a surface 12, an exciter element 14, an audio source 16a or audio signal receiver 16b, and an output amplifier 18, for generation of sound. In addition, the household appliance of fig. 5 comprises a control and processing unit 34. The control and processing unit 34 is connected on one hand to the audio source 16a or audio signal receiver 16b, and on the other hand to an analog-to-digital converter 36, which in turn is coupled to the exciter element 14 via an input amplifier 38. Optionally, the control and processing unit 34 is also coupled to other devices 40 of the household appliance.
The control and processing unit 34 is operable between a first state and a second state. In the first state, the audio source 16a or audio signal receiver 16b and output amplifier 18 are activated to apply the electric audio signal to the exciter element 14, whereas the analog-to-digital converter 36 and input amplifier 38 are deactivated. In the second state, control and processing unit 34 is ready to receive a second electric signal from the exciter element 14 via the input amplifier 38 and the analog-to-digital converter 36 (which consequently are activated), while the audio source 16a or audio signal receiver 16b and output amplifier 18 are deactivated. In the first state, sound can be generated as described above, while the second state allows for detection or measurements of vibrations, as will be described in more detail below. In the second state, the exciter element 14, namely an electrodynamic exciter element 14, is used like an electrodynamic microphone. The surface 12, which in the first state acts as a speaker panel, is used as a membrane of the electrodynamic microphone. When a vibration is induced in the surface 12, the vibration is passed on to the electrodynamic exciter element 14 mounted thereto, which in turn converts the vibration into a second electric signal. With reference again to fig. 2b, in the case of any vibration originating inside or outside a household appliance is passed on to the surface 12, the nonconductive part 24 starts to vibrate along with the surface 12. Since the constant magnet 26 has a bigger inertia, it substantially remains stationary. Hence, the distance between the coil 30 (which is wrapped around the part 24) and the magnet 26 starts to oscillate, whereby an alternating magnet field appears upon the coil 30, which in turn generates a Faraday voltage due to electromagnetic induction, whereby an electric signal is generated. The generated signal is a measure of the vibrations. The higher amplitude of this signal, the higher level of vibrations. Thus, the electrodynamic exciter element 14 operating in the described configuration can be used as an enhanced accelerometer replacing conventional accelerometers generally used in various household appliances.
Furthermore, back in fig. 5, the electric signal coming from the exciter element 14 is passed on to the input amplifier 38 for transformation to provide a detection signal. Such transformation may include amplification, filtration, rectification or other analogous transformation of the electric signal. The analog signal is thereafter converted to a digital signal by means of the analog to digital converter 36 before it is passed on to the control and processing unit 34. The control and processing unit 34 can then analyse the dynamic frequency content of the signal, allowing estimation of the characteristics of the corresponding vibration and its source or reason. Conveniently, the operation of the household appliance 10 can be affected in accordance with the detection signal. To this end, the control and processing unit is further adapted to generate a control signal in accordance with the detection signal, which control signal is transmitted to other devices 40 of the household appliance 10.
The vibration induced in the surface of the household appliance can originate from an event inside the appliance. For example, in a laundry machine, the above configuration could be used to monitor the drum speed, drain pump condition (ON/OFF), re-circulation pump condition (ON/OFF), weight of the unbalanced load, the falling of laundry from the top to the bottom of the drum, and additional vibrations. This kind of information then allows optimisation of the washing cycle and reduction of the noise level during operation. Further, in a dishwasher, the above configuration could be used to monitor the speed of the water spray arms (separately for upper and lower ones), main pump condition (ON/OFF), drain pump condition (ON/OFF), blocking of water spray arm(s), and take actions accordingly. Here, the exciter element(s) could advantageously be mounted to an interior surface of the appliance, depending on what event to detect or measure.
The above configuration can additionally be used to detect a vibration originating from an event outside of the household appliance, such as a user "knocking" on the appliance's surface. For this purpose, an electrodynamic exciter element is preferably mounted to the inside of the appliance's front panel only. When the user gently knocks the front panel, the knock causes a repercussion and a vibration pulse of the panel which is detected by the electrodynamic exciter element, whereby the control and process unit takes action accordingly. Thus, the user can gently knock the front panel whenever he or she wants the household appliance to execute a specific operation. The range of these specific operations include, but is not restricted to, the announcement of a voice message about the current status of the appliance, the automatic opening of a door of the appliance, emergency stop or interruption of a started washing cycle, etc. The various operations can for example correspond to and be identified by a single knock, double knocks, triple knocks, and so on, made by the user on any place of the appliance's front panel. Thus, a user interface is provided.
This user interface is especially useful for, but not limited to, built-in household appliances, where the appliance usually is covered by an exterior panel hiding the controls and display of the appliance. In this case, instead of opening the appliance to access controls and display, a user can simply knock on the front cover to execute commands, such as initiating a voice message about the current status of the appliance when a single knock is detected or automatically open the appliance' s door when a double knock is detected. Such functionality is especially advantageous for disabled people or when the user's hands are busy.
In an exemplary operation explained in relation to fig. 5, the household appliance 10 by default has nothing to pronounce, but it is waiting for the user's request. Hence the audio source 16a or audio signal receiver 16b and output amplifier 18 are switched off. Contrarily, the input amplifier 38 and analog-to-digital converter 36 are switched on. When the user is knocking on the surface 12 from the outside, the vibration pulse is passed on to the electrodynamic exciter element 14, which generates a corresponding electric pulse to be processed by the components 38 and 36. The control and processing unit 34 further detects the user's knock (s), then checks the current status of an appliance, then formulates a corresponding voice message to reply, then switches off the components 38 and 36, and then activates the audio source 16a and amplifier 18 to play a formulated message. After that a household appliance 10 goes back to the default state and the cycle repeats.
Thus, what just has been described is a household appliance with combined dual mode means for generating sound as well as detecting and measuring vibrations. It should however be noted that the household appliance in fig. 5 could be used without the speaker functionality. In such a configuration, the audio source or audio signal receiver and the output amplifier are omitted, leaving a household appliance comprising an exciter element mounted to a surface of the household appliance such that a vibration occurring in the surface is transferred to the exciter element, which generates an electric signal in accordance with the vibration, and means for receiving and optionally processing the second electric signal to provide a detection signal representative of the vibration.
The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, in the speaker embodiment, the exciter element(s) described above could alternatively be attached to an internal surface available inside the household appliance, which internal surface can vibrate and emit the sound. However, since the sound is supposed to go outside an appliance, the sound quality and loudness is impaired. Nevertheless, the use of large enough and flat enough internal surface or panel allows keeping this quality at acceptable level according to a specific application. Also, additional exciter elements (as in figs. 4a- 4c) can be used in the detection embodiment (for example fig. 5) to increase the detection and measurement accuracy.

Claims

A household appliance (10), comprising: an exciter element (14) mounted to a surface (12) of the household appliance such that a first electric signal applied to the exciter element is adapted to cause a corresponding first vibration of the exciter element, wherein the first electric signal is an audio signal, and wherein the surface is adapted to convert the first vibration to a sound, further comprising an audio source (16a) or audio signal receiver (16b) for providing the audio signal, said first vibration is adapted to be transferred to the surface, and a second vibration occurring in the surface is adapted to be transferred to the exciter element, which is adapted to generate a second electric signal in accordance with the second vibration, wherein the exciter element is an electrodynamic exciter element and wherein the household appliance further comprises means for receiving and optionally processing the second electrical signal to provide a detection signal representative of the second vibration, characterized in that the household appliance comprises a control and processing unit (34) for selectively activating the audio source (16a) or audio signal receiver (16b) and the means for receiving and optionally processing the second electric signal so that the household appliance is alternatively adapted to generate sound or detect vibrations via the surface (12).
A household appliance according to claim 1, wherein the control and processing unit (34) is operable between a first state and a second state, wherein in the first state, the audio source (16a) or audio signal receiver (16b) are activated to apply said audio signal to the exciter element (14), whereas the means for receiving and optionally processing the second electrical signal are deactivated, wherein in the second state, the audio source (16a) or audio signal receiver (16b) are deactivated, while the means for receiving and optionally processing the second electrical signal are activated to receive the second electric signal from the exciter element (14).
A household appliance according to claim 1 or 2, wherein the control and processing unit (34) is connected on one hand to the audio source (16a) or audio signal receiver (16b), and on the other hand to the exciter element (14).
A household appliance according to claim 3, wherein the means for receiving and optionally processing the second electric signal comprise an analog-to-digital converter (36) and an input amplifier 38.
A household appliance according to one of claims 1-4, wherein the frequency range of the exciter element is in the audible audio band.
A household appliance according to one of claims 1-5, wherein the control and processing unit (34) is connected to other devices (40) of the household appliance and is further adapted to generate a control signal in accordance with the detection signal for execution of a household appliance operation.
A household appliance according to one of claims 1-6, wherein the second vibration of the surface is caused by an internal event.
A household appliance according to one of claims 1-6, wherein the second vibration of the surface is caused by an external event.
A household appliance according to one of claims 1-7, wherein the surface is an exterior surface of a casing of the household appliance, and wherein the exciter element preferably is mounted to the inside of the surface.
A household appliance according to one of claims 1-9, wherein the surface is one of a front panel, a side panel, and a top panel of the household appliance.
A household appliance according to one of claims 1-10, wherein the household appliance is one of an oven, a microwave oven, a refrigerator, a freezer, a dishwasher, a laundering machine, and a tumbler dryer.