METHOD FOR DETECTING A LIQUID FILLING LEVEL OF A CONTAINER

Field of the invention

The present invention relates to a container for receiving a liquid, a beverage production system with the container and a beverage production machine comprising a beverage production unit and a control unit being configured to control a beverage production based on the liquid filling level of the container, and a method for detecting a liquid filling level of a corresponding container.

Background of the invention Containers for receiving a liquid for corresponding beverage production machines are well known in the prior art. Such a container can be a water tank to be attached to or associated with a corresponding beverage production machine to provide and supply a liquid - like water - for allowing the production of a beverage with the machine. The respective beverage production machines comprise a beverage production unit for preparing and dispensing a beverage by using the liquid from the liquid container. These beverage production units can, for instance, be designed to receive a capsule containing a food product to be produced/extracted - like coffee or tea - using the liquid provided by the liquid container (e.g. water tank). Thereby, the food ingredients (e.g. a beverage ingredient like coffee powder or tea leafs) provided in the capsule are made to interact with said liquid provided, e.g. under pressure, to the capsule in order to form a desired (liquid) comestible/beverage that is then made to leave the capsule and the beverage production unit.

The container for receiving a liquid can also be a drinking vessel like a cup or a mug for receiving the beverage which has been prepared and dispensed by the beverage production unit of the beverage production machine. For detecting the liquid filling level of the water tank, mechanical liquid level measurement means are usually used. Such liquid level measurement means can, for instance, be liquid level floats which may be combined with visual means reflecting the actual filling level of the respective tank. For detecting the flow rate of the liquid delivered from the liquid tank to the beverage production machine, flowmeters and particularly mechanical flowmeters are often used in present beverage production machines. These flowmeters are usually used for detecting the liquid amount being delivered to the beverage production unit from which the progress of an actual beverage production and/or the condition of the beverage production machine can be derived. For instance, a reduced flow rate may be an indication for liquid lines of the beverage production machine being clogged, e.g., due to scale. A detection means for the liquid filling level of a drinking vessel in connection with a corresponding beverage production machine is as such not yet known from the prior art. Liquid level detection as described before can be of high interest for the user while today most of the machines are not equipped with such a function for economic and/or aesthetic reasons. Moreover, most of the liquid level detection means are so-called liquid level floats which are bulky and space consuming while at the same time prone to catching due to a usually simple mechanical layout of the respective guidance of the floater elements. Additionally, machine integrated flowmeters can at most indirectly measure the filling level of a cup/mug which is associated with a beverage production machine.

The present invention seeks to address the above-described problems. The invention also aims at other objects and particularly the solution of other problems as will appear in the rest of the present description.

Summary of the invention In a first aspect, the present invention relates to a container for receiving a liquid (herein also referred to as liquid container) comprising a thin film capacitive sensor for detecting the liquid filling level of the container, wherein the sensor is attached onto the container and provided along the outer surface of the container. Such a container usually has a corresponding liquid (receiving) chamber having a maximum liquid filling level to be detected by the sensor.

Thin film technology is commonly known in the prior art. A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. For applying a thin film, a common technique is the so- called physical vapor deposition (PVD) covering a variety of vacuum deposition methods used for producing thin films. Physical vapor deposition uses physical processes like heating or sputtering to produce a vapor of material which is then deposited on a substrate.

Using a thin film capacitive sensor for detecting the liquid filling level of a corresponding container for receiving a liquid allows for an affordable and reliable sensor solution which can be easily provided to commonly known liquid containers while at the same time having no or only minor effect on the design (aesthetic) of the respective container due to its small dimensions particularly with respect to its thickness and preferably also its transparency.

Moreover, roll-to-roll processing (R2R) can be used by the production of thin film sensors which provides a good solution for cost optimization with respect to processes required for commonly known beverage production machine sensing elements like flowmeters and level floats.

The sensor of the present invention may be transparent and is preferably colorless. Using a transparent/colorless thin film capacitive sensor results in the sensor being more or less invisible thus not affecting the aesthetic of the container to which the sensor is applied.

In a preferred embodiment, the sensor comprises a conducting oxide deposition on a substrate, wherein the conducting oxide preferably is a transparent conducting oxide (TCO). Such transparent conducting oxides can, for instance, be indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), indium zinc oxide (IZO), indium cadmium oxide (ICO), antimony tin oxide (ATO), and fluor tin oxide (FTO). In particular, indium tin oxide (ITO) as transparent conducting oxide (TCO) is often used in the prior art due to its major properties, i.e. its electrical conductivity and optical transparency as well as the ease with which it can be deposited as a thin film.

The substrate can be made of glass (i.e. thin film of glass) or a polymer (i.e. thin film of polymer). The glass or polymer preferably is transparent. As a preferred polymer, polyethylene terephthalate (PET) can be used while also other corresponding materials or plastics are possible for providing a respective thin film substrate.

The sensor of the present invention preferably at least partially extends between a bottom and a top portion of the container to thus allow for a reliable detection of the liquid filling level of the container. In a preferred embodiment, the sensor extends from a bottom of the container - or at least from a bottom of a liquid chamber of the container - toward (or even up to) a top of the container - or at least a top of the liquid chamber of the container - and most preferably at least up to a (pre-defined) maximum liquid filling level of the container or the liquid chamber, respectively. In particular, the sensor is preferably provided such that it can detect the liquid filling level over the whole filling range of the container at least being defined by its liquid (receiving) chamber. Hence, the liquid filling level of the container can reliably be detected over its entire liquid filling range.

The sensor may comprise a connection portion for connecting the sensor to associated parts - e.g. of a beverage production machine - for a measurement operation. Such a connection portion can be an electric connection portion for electrically connecting the sensor. The electric connection portion can be a metalized portion like a metalized surface made of, for instance, a silver paste or the like. The electric connection portion can also be provided by the oxide deposition of the sensor itself. By means of the electric connection portion, the sensor and thus the container can be electrically connected, for instance, to an external element like a control unit of a beverage production machine.

The connection portion can also be a wireless connection portion for connecting the sensor, e.g., via data link. The wireless connection portion can be an RFID tag or the like. The wireless connection portion is preferably (electrically) connected to the oxide deposition of the sensor to receive the detected values of the sensor to be provided for data transmission to an associated part for measurement operation. By means of the wireless connection portion, the sensor and thus the container can be connected, for instance, to an external elennent like a control unit of a beverage production nnachine for respective data transmission.

In a preferred embodiment, the (electric or wireless) connection portion is provided at/on a bottom (portion) of the container. The invention, however, is not limited to this defined position as long as a corresponding connection is provided at a position which corresponds with a position of an associated means - e.g. an electric contact or a wireless transmission means like an RFID reader - of the beverage production machine or any other device with which the liquid container is to be (electrically or wirelessly) connected via the sensor.

In a preferred embodiment, the sensor is provided along the outer surface or at least partially within a side wall of the container. In the former embodiment, the sensor can be easily provided to the container, e.g., in the course of retrofitting. In the latter embodiment, the sensor can be easily integrated and thus preferably hidden within the container walls when producing the container, e.g., by way of injection molding. To provide the sensor or at least its connection portion at a bottom of the container for connection/contact with external devices, the sensor may be bent to extend along the bottom portion of the container.

As already noted, the container can be a drinking vessel, like a cup or a mug, for receiving a beverage prepared by a beverage production machine or a liquid tank for a beverage production machine, like a water tank. Such a liquid tank for a beverage production machine may comprise a liquid outlet portion fluidly connectable to a liquid inlet portion of a beverage production machine to thus allow for supply of the liquid, e.g., to a beverage production unit of the beverage production machine via respective piping.

In a preferred embodiment, the sensor can be attached onto the container, e.g. by being glued or welded. Therefore, the container may comprise an adhesive area for attaching the sensor onto the container. This adhesive area can be selectively provided with a releasable sealing cover when the sensor is not attached to the container to thus provide a protection film for the adhesive. The application onto the container can thus be easily done by peeling off the protection film and simply sticking the sensor onto the exposed adhesive area, i.e. onto the surface of the container to be equipped with the thin film capacitive sensor of the present invention.

In a preferred embodiment, the container is made of a dielectric material so that the thin film capacitive sensor can be used as one pole of a capacitor which can then be directly influenced by the liquid level inside the container forming the dielectric of the respective capacitor. The sensor can also be used as one pole of a capacitor being part of a corresponding beverage production machine. The capacitance measurement is preferably carried out like the detection of, for instance, a finger on a capacitive touch screen. In particular, a dedicated electronic - e.g. of the beverage production machine as described in the following - is able to monitor the changes in the capacity and thus to determine the liquid level of the tank. Moreover, the thin film capacitive sensor of the present invention may also be used to detect the flow rate of liquid being delivered from or supplied to the container which flow rate corresponds to the change of the liquid filling level of said liquid container over time. In other words, when the liquid filling level of the container changes, the capacity detected by the thin film capacitive sensor of the container changes as well. Based on the change of this capacity over time, the flow rate of the respective container from which liquid is discharged or to which liquid is supplied can be easily derived.

In a preferred embodiment, the container may comprise a (mechanical) coding to allow for a defined positioning/orientation of the container in association with the corresponding beverage production machine so that the sensor will securely be connected, e.g. electrically or wirelessly connected, to the beverage production machine. In a preferred embodiment, the container may further be provided with an RFID tag for providing data with respect to the container (e.g. maximum volume, filling level, correlation between capacity and filling level) to a beverage production machine which comprises a corresponding reader for receiving the stored data from the RFID tag of the container.

In a second aspect, the invention relates to a beverage production system comprising a beverage production machine having a beverage production unit for preparing and dispensing (i.e. producing) a beverage (like tea or coffee) and a control unit for controlling a beverage production of the beverage production unit, and a container according to the present invention. The sensor of the container is connected with the control unit when the container is associated with the machine. Therefore, the beverage production machine can comprise an electrical contact or a wireless (data) transmission means. The control unit is configured to control the beverage production based on the liquid filling level of the container detected by the sensor as exemplarily described herein above.

Even if the term "beverage" is used herein, the invention is not limited to the production of beverages but may cover all kinds of (liquid) comestible production (machines/systems), e.g. for producing tea, coffee, soups, baby food and the like.

In a preferred embodiment, the electrical contact can be an electrical spring contact being pretensioned toward the container when being associated with the machine. Hence, electrical contact between the control unit of the machine and the sensor of the liquid container can be ensured.

The wireless transmission means can be an RFID reader to be connected with the wireless connection portion, like an RFID tag, of the container. Hence, wireless connection between the control unit of the machine and the sensor of the liquid container can be easily provided. As already noted, the sensor can be one pole of a capacitor of the machine. The capacitor can either be provided as a part of the machine using the sensor of the container as one pole of the respective capacitor. Alternatively (or additionally), the capacitor can also be formed on the container itself in which the sensor forms one pole of this capacitor while the container wall forms the dielectric member of the capacitor and the liquid chamber inside the container provides the other pole of the capacitor.

The beverage production machine may further comprise a liquid inlet portion for fluidly connecting the container (i.e. the liquid chamber thereof) with the beverage production unit. To allow for a corresponding fluid connection, a liquid outlet portion of the container can be attached and thus fluidly connected with the mentioned liquid inlet portion. The liquid can then be delivered to the beverage production machine via a corresponding liquid line or piping of the beverage production machine using, for instance, a liquid pump of the beverage production unit.

In a third aspect, the invention relates to a method for detecting a liquid filling level of a container. The method comprises the steps of: · providing a beverage production system according to the present invention,

• associating the container according to the present invention with the beverage production machine such that the sensor of the container is (e.g. electrically or wirelessly) connected with the control unit, e.g. via the electrical contact or the wireless transmission means of the machine, and

• controlling the beverage production based on the liquid filling level of the container detected by the sensor.

The controlling of the beverage production is preferably carried out by the control unit of the beverage production machine. For instance, the control unit can detect whether or not enough liquid is provided inside the liquid tank of the beverage production system to allow for the production of a selected beverage to be produced. If so, beverage production can be started. In case that not enough liquid is provided inside the container for producing the selected beverage, the beverage production is not started. In a preferred embodiment, a visual or acoustic signal can be generated to call the user's intention to the insufficient liquid filling level of the associated liquid tank.

Moreover, if the container is a drinking vessel for receiving the produced and dispensed beverage of the beverage production machine with which the container is associated through electrical contact or wireless connection via the sensor, a maximum liquid filling level of the container can be defined according to which - when being reached and detected by the sensor - the beverage production is stopped, e.g., by the control unit. Hence, the present invention may also provide an overflow protection. To allow for the beverage production machine determining the maximum liquid filling level of the container, such data can, for instance, be provided on a corresponding RFID tag of the container and which data can then be transferred by a corresponding reader of the beverage production machine to the control unit as already described herein above.

To allow for a secure connection of the sensor and maybe also a correct positioning of an RFID tag with respect to a corresponding reader of the machine, the container can comprise corresponding (mechanical) coding as described herein above.

In a preferred embodiment, the control unit can also control the beverage production based on the flow rate derived from a change of the liquid filling level of the container detected by the sensor during the beverage production. This can be achieved by simply detecting the liquid filling level of the container over time, e.g. a plurality of times based on a predefined time interval during the beverage production. From the change of the liquid filling level over time, the flow rate can directly be derived. Based on the received data with respect to the flow rate, the beverage production machine and in particular, the beverage production unit can be controlled to allow for a desired flow rate. Moreover, the proper functioning of the beverage production machine can be controlled based on a comparison, for instance, of a target flow rate and an actual flow rate. Hence, clogging or the like, e.g. being the result of scale, can be detected and a corresponding visual and/or acoustic indication can be output.

The present invention thus allows for a level detection and preferably also a flow rate detection of a corresponding container being associated with the respective beverage production machine.

Brief description of the drawings

Additional features and advantages of the present invention are described in, and will be apparent from, the description of the presently preferred embodiments which are set out below with reference to the drawings in which:

Figure 1 shows a perspective view of a beverage production system according to a first embodiment of the present invention,

Figure 2 shows a perspective view of a container according to a first embodiment of the present invention as also shown in figure 1,

Figure 3 shows detail II at a bottom region of the container of figure 2,

Figure 4 shows a simplified perspective view of a thin film capacitive sensor as used in the present invention,

Figure 5 shows a simplified rear view (figure 5a) and side view (figure 5b) of the container of figure 1 in association with a beverage production machine of which only an electric spring contact is shown,

Figure 6 shows a schematic view of the beverage production system according to a second embodiment of the present invention with two different embodiments of liquid containers according to the present invention. Detailed description of the invention

Figure 1 shows a beverage production machine 1 with two possible kinds of containers 2 for receiving a liquid L according to the present invention. Beverage production nnachine 1 and liquid container 2 together form a beverage production system S according to the present invention. The beverage production machine 1 can be any kind of beverage production machine for producing and dispensing a (liquid) comestible or beverage. Such a machine 1 can, for instance, be a coffee machine for preparing coffee, e.g. from a capsule containing coffee powder, by extraction with a hot and preferably pressurized liquid (e.g. water) within a capsule receiving chamber.

The liquid container 2 can be a drinking vessel 2', like a cup or a mug, as depicted in figure 6, and/or it can be a liquid tank 2" for said beverage production machine 1, like a water tank, as depicted in figures 1 to 3, 5 and 6.

With respect to figure 6, the beverage production machine 1 comprises a beverage production unit 10 for preparing and dispensing a comestible/beverage. The beverage production unit 10 can comprise a capsule receiving chamber as defined herein above for receiving a capsule comprising, for instance, coffee powder to be extracted. The beverage production unit 10 may further comprise a liquid pump to provide pressurized liquid - e.g. from the liquid tank 2" - to the beverage production unit 10, e.g. the capsule receiving chamber. The beverage production unit 10 may further comprise a beverage outlet 11 for dispensing the produced/extracted beverage.

The beverage production machine 1 further comprises a control unit 50 for controlling the beverage production of the beverage production unit 10. Therefore, the control unit 50 and the beverage production unit 10 are electrically connected 51.

Moreover, the beverage production nnachine 10 may further comprise input and/or output means 30, like a (touch) panel, signal lights, a loud speaker for generating acoustic signals, and/or buttons for selecting and initiating beverage production programs. Therefore, the input/output means 30 are (electrically) connected 52 with the control unit 50. The beverage production machine 1 may further comprise a dripping tray (which may also function as a drinking vessel receiving member) 40 for receiving leaking liquid or liquid which is dispensed by the beverage production unit 10 during a cleaning program of the beverage production machine 1. For electrical connection of the beverage production machine 1, the beverage production machine 1 may further comprise a power cable 80 (see figure 1).

The liquid container 2 which - as such - is also covered by the present invention is shown as a liquid tank 2" in more detail in figure 2.

The liquid container 2 according to figures 1 and 2 is a liquid or a water tank 2" to provide a corresponding liquid L - typically water - for the production of a beverage/comestible to be produced by the beverage production machine 1. The liquid container 2 therefore comprises a liquid (receiving) chamber 20 for receiving a dedicated amount of liquid L. Moreover, the liquid container 2 according to figures 1 and 2 further comprises a liquid outlet portion 21 which can be fluidly connected to a corresponding liquid inlet portion 61 of the beverage production machine 1. The liquid inlet portion 61 of the beverage production machine 1 can be part of a liquid container receiving portion 60 of the beverage production machine 1 which can be configured to receive the liquid container 2 preferably by means of corresponding contours and/or mechanical receiving means (e.g. coding). The receiving means can, for instance, be designed to mechanically catch the liquid container 2 by corresponding (releasable) locking means (not shown).

As can be gathered from figures 1 to 3 and 5, the liquid container 2 comprises a thin film capacitive sensor 100 for detecting the liquid filling level of the liquid container 2.

In a preferred embodiment, the sensor 100 is transparent and preferably colorless. In the embodiments of the figures, the shown sensors 100 are highlighted for demonstrating purposes only.

The sensor 100 can be a conducting oxide deposition 101 on a substrate 102 as shown in a simplified manner in figure 4. The conducting oxide 101 of such a sensor 100 preferably is a transparent conducting oxide (TCO). Such a TCO is preferably an indium tin oxide (ITO) being electrically conductive and optically transparent and can be easily deposited as a thin film. Other alternatives to ITO are, for instance, aluminum zinc oxide (AZO), gallium zinc oxide (GZO), indium zinc oxide (IZO), indium cadmium oxide (ICO), antimony tin oxide (ATO), and fluor tin oxide (FTO). As a material for the substrate 102 there is preferably used glass or a polymer. The glass and polymer are preferably transparent. As an example, polyethylene terephthalate (PET) is used as such a transparent polymer. To provide a thin film capacitive sensor 100, the substrate 102 is provided as a thin strip (i.e. thin film) onto which the respective conducting oxide 101 is deposited by corresponding deposition techniques.

The use of a transparent and preferably colorless sensor 100 has no or only a minor negative aesthetic effect (i.e. it is almost invisible) when being provided onto a corresponding liquid container 2. This is particularly true for transparent liquid containers 2 commonly used in the prior art.

To allow for an accurate measurement of the liquid filling level of the container 2, the sensor 100 can at least partially extend between a bottom portion 22 and a top portion 23 of the liquid container 2. In a preferred embodiment, the sensor 100 extends from the bottom 22 of the container 2 - or at least from the bottom 202 (level) of the liquid chamber 20 of the liquid container 2 - towards the top 23 of the container 2, preferably a top 203 (level) of the liquid chamber 20 of the container 2. In a preferred embodiment, the sensor 100 extends at least up to a maximum filling level 24, 204 of the container 2 or the liquid chamber 20 as can be seen in figure 5.

To allow for a secure electrical connection of the sensor 100 (e.g. to the control unit 50), the sensor 100 may comprise an electric connection portion 103. This electric connection portion 103 can be a metallized portion such as a silver pad or the like which is in direct contact with the conducting oxide 101. The electric connection portion 103 is preferably provided at a bottom portion 22 of the container 2 so that it can get in contact with a corresponding electric contact 63 of the beverage production machine 1 when being associated with - e.g. placed onto - the beverage production machine 1 and in particular on/in a corresponding liquid container receiving portion 60. As can be seen in figures 3 and 5b, the sensor 100 can be bent at a bottom end thereof to extend along the bottom 22 of the container 2 to thus provide the electric connection portion 103 facing a corresponding electric contact 63 of the beverage production machine 1. Of course, the electric connection portion 103 can also be provided at any other portion of the sensor 100 which faces and gets into electrical contact with a corresponding electric contact 63 of the beverage production machine 1 when the liquid container 2 is associated with (e.g. placed onto) the beverage production machine 1. The electric connection portion can also be provided by the oxide deposition 101 of the sensor 100 itself. The electric contact 63 of the beverage production machine 1 is preferably electrically connected 53 with the control unit 50 as exemplarily shown in figure 6. Hence, the electrical contact 63 allows for electrically connecting the sensor 100 of the container 2 with the control unit 50 when the container 2 is associated with the machine 1.

To allow for a secure electrical connection of the sensor 100 with the beverage production machine 1, the electrical contact 63 preferably is an electrical spring contact as exemplarily depicted in figure 5. This electrical spring contact 63 is pretensioned towards the container 2 when being associated with the machine 1, e.g. when being placed onto the beverage production machine 1 e.g. when the container 2 is received within the liquid container receiving portion 60.

Alternatively, the shown electric connection portion 103 can also be replaced by a wireless connection portion like an RFID tag. This RFID tag is then preferably connected with the oxide deposition 101 of the sensor 100 to receive the detected values of the sensor 100 to be provided for data transmission to an associated part of the machine 1 for measurement operation. According to this embodiment, the electrical spring contact 63 can be replaced by a wireless transmission means preferably being electrically connected with the control unit 50. Hence, the wireless connection portion can be used for wireless connection with the wireless transmission means for connecting the sensor 100, e.g. via data link, with the control unit 50 when the container 2 is associated with the beverage production machine 1 as already described herein above. The wireless connection portion and wireless transmission means can thus be used in a similar way as the electric connection portion 103 and electrical spring contact 63 to provide wireless rather than electrical connection. For further details it is thus referred to the description of the electric connection portion 103 and electrical spring contact 63 as given herein above.

As can be gathered from figures 2, 5 and 6, the sensor 100 can be provided along the outer surface or at least partially within a sidewall of the container 2. In the latter case, the sensor 100 can be integrated within the (sidewall of the) container 2 when producing the container 2, e.g., by an injection molding process. Alternatively, when providing the sensor 100 along an outside surface of the container 2, the sensor 100 can be attached onto the container 2, e.g., by being glued or welded. In a preferred embodiment, the container 2 may comprise an adhesive area 25 for attaching the sensor 100 onto the container 2 (see figure 2). In a preferred embodiment, the adhesive area 25 can be selectively provided with a releasable sealing cover (not shown) when the sensor 100 is not attached to the container 2. Thus, the container 2 can be retrofitted with a thin film capacitive sensor 100 to provide a liquid container 2 according to the present invention. The thin film capacitive sensor 100 of the present invention preferably forms one pole of a capacitor of the beverage production machine 1 and preferably a capacitor of the container 2. In a preferred embodiment, the container 2 can be made of a dielectric material so that the thin film capacitive sensor 100 and the container 2 form the capacitor in combination with the liquid (receiving) chamber 20 not, partially or completely filled with a corresponding liquid L, like water. Due to the filling level of the liquid L in the container 2, the capacity being detected by the sensor 100 changes from which then the filling level can be directly derived, e.g. by the control unit 50.

Just as an example, figure 5 shows the liquid container 2 being partially filled with a liquid L. As only a part (surface B) of the sensor 100 extends along a container 2 region being filled with liquid L while the other part (surface A) of the sensor 100 extends along a container 2 region being empty - i.e. not being filled with liquid L but only with air - there will be a particular capacity being detected by the sensor 100 which differs dependent on the ratio of surface A and surface B. Based on the detected capacity, the liquid filling level can be directly derived, e.g. by the control unit 50. The control unit 50 is thus configured to control the beverage production based on the liquid filling level of the container 2 detected by the sensor 100. The beverage production can thus be controlled based on the result of the liquid filling level or liquid flow rate of the liquid discharged from the liquid container 2. Therefore, the beverage production machine 1 or system S according to the present invention allows for beverage production control simply based on the result of the liquid filling level detected by the thin film capacitive sensor 100 of the present invention replacing commonly used liquid level floats and/or flowmeters commonly used in the prior art. The sensor elements can thus be simplified resulting in a more economic and aesthetic beverage production machine 1 or system S and liquid container 2.

To allow for a delivery of the liquid - like water - from the liquid tank 2 to the beverage production unit 10 for producing/extracting a beverage, a corresponding liquid pipe or line 70 is provided connecting the liquid inlet portion 61 with the beverage production unit 10. The liquid can be delivered by means of a liquid pump being provided in the beverage production unit 10 when the liquid container 2 is in fluid connection with said beverage production unit 10, e.g., via its liquid outlet portion 21 being fluidly connected to the liquid inlet portion 61.

As already noted and depicted in figure 6, the liquid container 2 can also be designed as a drinking vessel 2', like a cup or a mug. This drinking vessel 2' comprises a thin film capacitive sensor 100 in the same way as the liquid tank 2" described herein above for detecting the liquid filling level of said drinking vessel 2'. The liquid filling level detected by the respective sensor 100 of the drinking vessel 2' can, according to this embodiment, be used as an overflow protection. For instance, the beverage production of the beverage production unit 10 of the beverage production machine 1 can be stopped, e.g. by the control unit 50 of the beverage production machine 1, when a predefined maximum filling level of the drinking vessel 2' has been reached and is detected by the sensor 100. Therefore, the sensor 100 is electrically connected to a corresponding electric contact 43, e.g., via an electric connection portion 103 of the sensor 100. The electric contact 43 for the drinking vessel 2' is functionally similar to the electric contact 63 for the liquid tank 2" and preferably also electrically connected 54 to the control unit 10. Alternatively, instead of the electric connection portion 103 and electric contact 43, the drinking vessel 2' can also comprise a wireless connection portion (e.g. RFID tag) and the beverage production machine 1 can comprise a wireless transmission means for wireless data link and transmission, as already described for the water tank 2 herein above. Hence, for further details it is referred to the corresponding description given herein above. To allow for a correct positioning of the connection members and thus a secure connection of the sensor 100 with the electric contact 43 or wireless transmission means, the beverage production system S, preferably the drinking vessel receiving member 40 on the one side and the drinking vessel 2' on the other side, may comprise correspond ing mechanical coding means to al low for a unique position ing/orientation of the drin king vessel 2' with respect to the beverage prod uction mach ine 1 and particularly the electric contact 43 or wireless transm ission means.

The control un it 50 m ight be configu red such that it interru pts or does not in itiate beverage production by the beverage production un it 10 or at least outputs a signal via the output means 30 when it does not detect a contact with a corresponding sensor 100 via the respective electric contacts 43, 63 or a con nection with a corresponding sensor 100 - or better its wireless con nection portion (e.g. RFID tag) - via the respective wireless transmission means.

The liquid container 2 (here the drinking vessel 2') may further comprise an RFID tag 26 or the l ike com prising data l ike the maximu m fill ing level and volu me of the drinking vessel 2' and corresponding capacity val ues regard ing the respective fill ing levels. The RFI D tag 26 can be identical with the RFID tag being provided as wireless connection portion as described herein above. The mentioned data can be received by using a correspond ing reader 80 of the beverage prod uction mach ine 1 being electrically connected 55 to the control u nit 50 corresponding for beverage production control. This reader 80 can be identical with the wireless transmission means as described herein above. For instance, beverage production can be stopped once a defined maximu m fill ing level of the drinking vessel 2' - being stored in the RFI D tag 26 and detected by the sensor 100 - has been reached.

I n the following, a method for detecting a liquid fill ing level of a container 2 wil l be described. I n a first step of said method, a beverage production system S accord ing to the present invention - i.e. having the beverage production machine 1 and the l iqu id container 2 - is provided.

I n a second step, the container 2 (2', 2") accord ing to the present invention is associated with the beverage prod uction mach ine 1 such that the sensor 100 of the container 2 is con nected with the control un it 50, e.g. via the electrical contact 43, 63 or the wireless transmission means of the beverage production mach ine 1.

I n a third step of the method, the beverage production is controlled based on the liquid fill ing level of the container 2 (2', 2") detected by the sensor 100.

I n a preferred embod iment, the control u nit 50 controls the beverage prod uction based on the flow rate derived from the change of the liqu id fill ing level of the container 2 detected by the sensor 100 du ring the beverage production; i.e. detected over time. The liquid fill ing level of the container 2 ca n, for instance, be detected a pl ural ity of times du ring beverage production. The control u nit 50 can then directly derive the actual flow rate of the liquid. The measu red actual flow rate can then be used for control of the beverage production or the beverage prod uction machine 1. For instance, a req uired liqu id flow rate can be controlled based on the actual flow rate. Moreover, malfu nction of the beverage prod uction machine 1 can be detected if the actual flow rate deviates from a (pre-defined) target flow rate by a (pre-defined) amount. Hence, scale or clogging or malfunction of a liq uid pump can be indirectly detected.

It should be understood that various changes and mod ifications to the presently preferred embod iments described herein will be apparent to those skil led in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.