DE102008031783A1 - Sensor device i.e. capacitive sensor, for detecting water filling level in container of condenser laundry dryer, has client circuit supplied with electric fields, generated by server circuit, to provide energy for operating client circuit - Google Patents

Abstract

The device has a client circuit with a client (23) for generating signals. A server circuit with a server (12) detects the signals and generates electrical fields. The client circuit includes a set of electrodes (21, 22), and is coupled to the server circuit on the basis of a modulated alternating field. The client circuit is supplied with electric fields to provide energy for operating the client circuit. The circuits are pressed on a film (30) i.e. polymer film. The electrodes and a server electrode (11) are parallel to each other. Oscillators are provided in the client circuits.

Description

The The invention relates to a sensor device for detecting the fill level in a container, wherein the sensor device at least one client circuit for Generation of signals and a server circuit for detection the signals generated and output by the client circuit includes. The server circuit simultaneously serves to generate an electric field. Especially The invention is directed to a sensor device for detection the level in a container with the help of capacitive sensors.

Out The prior art devices or systems are known to the level a container capture. For example, systems are known in which the level a container under With the help of mechanical devices is determined. For example is known in the water tank a condenser tumble dryer Provide polystyrene floats, which upon reaching a predetermined Water level operate an electric switch. However, this requires An additional Structural effort of the condensate dryer used water tank.

Of Further takes the arranged inside the container mechanical Device, such as a polystyrene swimmer, extra space, resulting in on the from the container absorbable amount of water has a negative effect.

Of Furthermore, it is necessary to provide a corresponding opening in the container, from the outside to the inside of the container arranged mechanical level measuring device, in the case of a defect, for example.

alternative For this purpose, from the prior art and optical and electrical Measuring systems for determining the water level in a container known. Optical measuring systems necessarily require that if that Measuring system outside of the container is arranged, at least a part of the container designed to be transparent is. In the case of electrical measuring systems, the conductivity use the water to determine the level, it is necessary to arrange this at least partially inside the container, to make contact with the water. Measuring systems, which on the conductivity of the water, have the disadvantage that, for example, contaminated Water a different conductivity may be as clean water, resulting in considerable measurement inaccuracies or measuring errors can.

Especially Such an electrical measuring system must each on the electrical conductivity the liquid in a container adjusted or adjusted to an exact level measurement to be able to make.

task The present invention is a sensor device for detection of the level in a container to provide those known from the prior art Disadvantages at least partially avoids, wherein the sensor device at the same time universal, space-saving and easy to use.

According to the invention this Task with a sensor device according to the features of the claim 1 solved.

After that includes the sensor device for detecting the level in a container at least one client circuit for generating signals and a server circuit for detecting the from the client circuit generated and output signals and for generating an electrical Field, wherein the at least one client circuit, a first electrode CE1 and a second electrode CE2, wherein the at least a client circuit based on a modulated alternating field is coupled to the server circuit and wherein the at least a client circuit with that generated by the server circuit electric field supplied with power to operate the client circuit becomes.

The Server circuit can also be at least one electrode SE (a so-called Server electrode). The client circuit can be based on this of the modulated alternating field coupled to the server circuit be.

By the capacitive coupling of the client circuit to the server circuit can by the recorded by the client circuit or their electrodes Alternating field can be used to power the client circuit to supply, so on additional Power supplies omitted in the client circuit can be.

The Electrodes CE1 and CE2 of the client circuit as well as the electrode SE the server circuit can band-like be configured and arranged substantially parallel to each other. The distance of the first electrode CE1 to the electrode SE is preferably smaller than the distance of the second electrode CE2 to the electrode SE.

In An advantageous embodiment of the invention are the electrodes CE1 and SE narrow in relation designed to the electrode CE2.

By placing the first electrode CE1 (coupling electrode) of the client circuit in close proximity to the server electrode SE and the schma le embodiment of the server electrode SE and the coupling electrode CE1 is achieved a particularly good coupling of the electrodes CE1 and SE to each other with a small mass coupling. The greater width of the output electrode CE2 has the advantage that a particularly good coupling of this electrode to ground is achieved.

Preferably Can the at least one client circuit and the server circuit on a foil sticker be arranged. Particularly preferably Kings nen the client circuit and the server circuit to be printed on a polymer film, what a particularly flexible use of the sensor device according to the invention allows. The sensor device can be so easy on the level to be monitored container be attached, wherein the filling level to be detected by the mounting height of the sticker chosen becomes.

The Power supply to operate the client circuit can be through the Voltage drop between the first electrode CE1 and the second electrode CE2 be accomplished. The above The first electrode CE1 received alternating field is advantageously converted into a DC voltage (such as through a diode cascade), so with this rectified working voltage the client circuit can be operated.

According to the invention Power supply of at least one client circuit interrupted as soon as the voltage drop between the first electrode CE1 and the second electrode CE2 below a predetermined value decreases. This is the case as soon as possible the filling level in the in terms of level to be monitored Container inside the width of the coupling electrode CE1 is located. At this time turns off the client circuit, as the voltage drop between the Einkoppelelektrode CE1 and the Auskoppelelektrode CE2 not more sufficient to power the client circuit.

advantageously, can the sensor device or the film sticker in operation the outside of the container be arranged, resulting in a particularly simple detection of the level in a container allows. In that not the conductivity a liquid but uses its dielectric constant as a sensor function is, the sensor device according to the invention must not in contact with the liquid in the container stand, because the change the electric field between the electrodes is used, which changes with increasing level. At the same time reduced in size with increasing liquid level in the container also the voltage drop between the electrodes of the client circuit, wherein the voltage drop when reaching the coupling electrode CE1 finally so Small becomes that the client circuit off.

The Turning off the client circuit may be through the sensor device or by the server circuit as exceeding a predetermined liquid level be interpreted. The sensor device thus provides a clear Signal, namely by switching off the client circuit ready as soon as the fluid level is exceeded becomes.

The has sensor device according to the invention also the advantage that even water levels in containers, which are not electrically absorb conductive liquids, can be determined.

By the electrodes arranged substantially parallel to one another the server circuit and the client circuit can control the level which turns off the client circuit automatically, only by determines the vertical arrangement of the sensor device to the container become.

The Server circuit further includes a power supply, a Oscillator and an evaluation unit, wherein the oscillator of the power supply is operated and wherein the evaluation unit the modulated alternating field provided by the client circuit supplied becomes. This allows a sensor device with two or more client circuits be provided, which are designed so that this through the server circuit are distinguishable.

The Client circuits can each having a comparator, which one of the server circuit on the modulated by these generated electric field identification number compared with a comparison identification number. The client circuit can additionally be designed so that it can only be activated if the identification number the comparison identification number corresponds, wherein each client circuit a different (or unique) comparison identification number assigned.

The Server circuit can thus target one of several client circuits activate. This has the advantage of being connected to a server electrode simultaneously multiple client circuits can be coupled, so for example different levels can be detected with a sensor device of the type according to the invention are.

As an alternative to the comparator, two or more client circuits may also each have a timer, wherein the timers activate the respective client circuits in a predetermined order and duration. Also here In each case exactly one client circuit is coupled to the server electrode, so that likewise different water levels in a container can be detected.

In a further alternative embodiment can the client circuits also each have a free-running oscillator have, wherein the frequency of the respective oscillators different is. Due to the different frequency of the individual oscillators the client circuits are distinguishable from the server circuit.

In In yet another alternative embodiment, the Client-circuits also each have a frequency divider, which is the frequency the oscillator of the server circuit divides, the division ratio of the individual frequency divider is different. Again, the different serves Frequency of each client circuits that the server circuit the individual client circuits can differ.

Further Advantages and advantageous embodiments of the invention are the Description, the drawings and claims removed.

embodiments the invention are shown schematically simplified in the drawing and will be explained in more detail in the following description.

It shows:

1 a sensor device according to the invention, arranged on a foil;

2 a sensor device arranged on a tank to be monitored with regard to the water level;

3 an embodiment of the sensor device according to the invention for detecting different filling levels;

4 an embodiment of the sensor device according to the invention with a server circuit and two client circuits;

5 an example of a sensor device, which allows both the determination of the level in a container and tilting movements of a partially filled with liquid container;

6a a schematic representation of the server circuit according to the invention; and

6b a schematic representation of a client circuit.

1 shows a sensor device for detecting the level in a container, wherein parts of the sensor device on a foil 30 , are preferably applied to a polymer film. The sensor device consists of a server circuit and a client circuit. The server circuit is from a server 12 and one with the server 12 coupled server electrode 11 educated. The coupling of the server electrode 11 with the server 12 can be galvanic or capacitive.

The client circuit is handled by a client 23 and two with the client 23 coupled electrodes 21 . 22 educated. The electrode 21 the client circuit, which serves as a coupling-in electrode, is in the immediate vicinity of the server electrode 11 arranged. The electrode 22 , which serves as Auskoppelelektrode, however, is further from the server electrode 11 arranged away.

How out 1 is apparent, are the server electrode 11 and the coupling-in electrode 21 narrower than the Auskoppelelektrode 22 , Due to the narrow design of the server electrode 11 and the coupling electrode 21 a particularly good coupling of these electrodes to each other is achieved with simultaneous low mass coupling. Moreover, in a narrow embodiment of the coupling-in electrode 21 the switching threshold at which the power supply of the client circuit is interrupted, also correspondingly narrow.

The much larger width of the coupling-out electrode 22 serves to provide a better coupling of the electrode 22 to achieve mass.

The client circuit, consisting of the electrodes 21 . 22 and the client 23 , Capacitive is coupled to an alternating electric field, which from the server 12 and the server electrode 11 provided. The alternating electric field of the server or the server electrode 11 is in the coupling electrode 21 the client circuit coupled while the Auskoppelelektrode 22 (capacitive) connected to ground.

That via the coupling-in electrode 21 recorded AC field can be from the client 23 be converted into a DC voltage with a voltage converter, for example, operates an oscillator, which has a certain level according to the input voltage, which is sufficient to provide power to the client circuit.

By means of physical action variables, such as the level in the container to be monitored, it is possible to change the level of the voltage so that it is proportional to the size acting on the server 12 can be evaluated and thus a measure of the acting Size forms, about the current level in the container to be monitored.

A detailed description of the client circuit or server circuit is given below with reference to FIG 6a and 6b given.

According to the construction of the sensor device according to the invention, the activation of the client circuit always takes place when via the server electrode 11 from the server 12 a sufficiently strong electric field is provided so that the oscillator of the client circuit can swing, which in turn can be evaluated by the server circuit as an "OK" signal.

The for example, the signal generated by the client circuit (OK signal) be transmitted via load modulation to the server circuit. The transmitted Signal is supplied to the server circuit of an evaluation unit where it For example, a Fourier transform can be subjected.

According to the structure of the invention the sensor device becomes the signal from the client circuit so long communicated to the server circuit, as long as the client circuit has sufficient energy out of it Server circuit provided AC field for their operation.

The operating principle of the sensor device according to the invention is the following. The distance between the coupling electrode 21 and the coupling-out electrode 22 is chosen so that the client circuit will operate stably at the selected server voltage with no liquid in the container (eg, water), ie the oscillator will stably oscillate the client circuit, which will be detected by the server circuitry as the aforementioned "sensor -OK "signal can be evaluated. In this initial state, ie when there is no liquid in the container, there is a sufficient voltage drop between the coupling electrode 21 and the coupling-out electrode 22 so that the client circuit can be supplied with enough power for operation.

By filling, for example, water, into the container (where water has a dielectric constant of about 80), the "distance" between the electrodes effectively acting on the electric field becomes effective 21 and 22 shortened by ε-fold, ie that the voltage drop between the coupling electrode 21 and the coupling-out electrode 22 decreases with increasing liquid level.

The client circuit turns off as soon as the voltage drop between the coupling electrode 21 and the coupling-out electrode 22 is no longer sufficient to power the client circuit. Preferably, the shutdown takes place when the liquid level is within the width of the coupling electrode 21 located.

As a result, the client circuit transmits a signal to the server, for example by means of load modulation, as long as the liquid in the container to be monitored has not reached a predetermined level. After reaching the level, the client circuit automatically shuts off, as the voltage drop between the coupling electrode 21 and the coupling-out electrode 22 falls below a certain value, which can be evaluated by the server circuit and clearly recognized. This signal assignment (level reached or level not reached) has significant safety advantages, since the achievement of a level in a container is clearly identified by exactly one signal. A continuous monitoring of the liquid level in the container is not required, which is particularly advantageous in the design of the evaluation in the server circuit, since complicated circuit arrangements, for example, for a pattern comparison for different levels of a liquid in a container are not necessary. The evaluation unit only has to check whether a signal is provided by the client circuit or not.

Of course you can the server circuit or the evaluation of the server circuit the received signal from the client circuit also in terms of liquid level in the container evaluate, for example, different status or warning messages to disposal to deliver.

2 shows a container 40 with a sensor device arranged on the outside of the container, consisting of the server 12 , the server electrode 11 , the coupling electrode 21 , the decoupling electrode 22 as well as the client 23 , In addition, the server 12 with a warning device 50 , For example, an LED connected. The evaluation device of the server circuit 12 can be designed so that upon reaching the level to be monitored in the container 40 the LED starts to light up or starts flashing. The level to be monitored is located in the region of the coupling-in electrode 21 ,

If the individual elements of the sensor device are arranged on a foil, then this foil can be easily attached to the container to be monitored with respect to the filling level on the outside of the container, wherein only care must be taken that the mounting height of the foil is chosen such that the Height of the coupling electrode 21 corresponds to the level to be detected in the container.

According to the invention, the server 12 also be operated with an external, not located on the container power source. It is also not mandatory, the warning device 50 directly on the outside of the container 40 to arrange. For example, the warning device 50 be guided to a control panel, such as a clothes dryer, wherein the sensor device can be used to detect the water level in the container of Kondenswäschetrockners. Using the sensor device according to the invention, it is particularly easy to provide already existing devices with a sensor device for detecting the fill level. Thus, the container of a condenser dryer must be provided only with the sensor device according to the invention, wherein in the case that the sensor device is arranged on a self-adhesive film, the film must be glued only at a suitable location on the outer wall of the container. A possibly existing warning device only needs to be made visible or audible to the operator at a suitable point.

One further conversion or adaptation of the container of the condensate dryer is no longer necessary. In particular, no facilities need or devices for detecting the level inside the container become.

3 shows an alternative embodiment of a sensor device according to the invention, which on a film 30 arranged. In the 3 shown sensor device is used to detect two different levels in a container, so as to trigger different actions depending on the filling level. For example, upon reaching a first fill level, a warning function can be triggered, and upon reaching a second fill level, for example, the liquid supply in the container to be monitored can be automatically stopped.

As in 3 As can be seen, the electrodes are 11 . 21 . 22 a first sensor device different from the electrodes 11a . 21a . 22a a second sensor device arranged so as to achieve the detection of different levels in a container. In the embodiment shown here, the server electrodes are 11 respectively. 11a the two sensor devices each with a server 12 respectively. 12a connected. If the filling level of the liquid in the container reaches the coupling-in electrode 21a , can be detected by the second sensor device, a first level, since the voltage drop between the coupling electrode 21a and the coupling-out electrode 22a is no longer sufficient to the client circuit of the second sensor device with that of the server electrode 11a to supply the electric field provided with energy. The client circuit of the second sensor device thus switches on reaching the filling level in the region of the coupling-in electrode 21a automatically, leaving the evaluation of the server 12a can trigger a corresponding function. For example, this feature may be a warning feature that indicates that a critical level has been reached in the tank.

The evaluation device of the server 12a For example, it is also possible to control a regulating device which controls the supply of liquid in the container when the liquid level is reached 21a throttles accordingly.

The server electrode 11 and the coupling-in electrode 21 The first sensor device are correspondingly vertically above the server electrode 11a or the coupling-in electrode 21a the second sensor device arranged. With a further increase in the fill level, this finally reaches the coupling-in electrode 21 , so that the evaluation of the server 12 can detect this level, for example, then automatically stop the supply of liquid into the container.

Of course, the servers can 12 and 12a Also have a common evaluation, said common evaluation can control both the warning function for the first level and the automatic stopping of the liquid supply at the second level.

The first sensor device operates analogously to the already described operation of the second sensor device. If the liquid level reaches the coupling-in electrode 21 , the voltage drop between the coupling electrode decreases 21 and the coupling-out electrode 22 below a certain value which is too low to power the client circuitry of the first sensor device. The client circuit of the first sensor device then switches off automatically.

In a further embodiment, the electrode 11a the second sensor device also with the server 12 get connected. The electrodes 11 and 11a are designed so that the server 12 can distinguish the signals generated by the two client circuits (OK signals). Various design options for distinguishing the signals generated by a plurality of client circuits are provided below with reference to 4 and 6b listed.

In this embodiment (a server 12 ge couples with multiple electrodes 11 . 11a ) can be on the second server 12a be omitted, which allows a more compact design of the sensor device according to the invention.

Especially Is it possible one or more client circuit of the type mentioned to one already to connect existing server, making a network of client circuits can be built. For example, in a tumble dryer Server be provided, on which one intended for a different purpose Sensor device is connected. On this server can also the client circuit according to the invention be connected. The server is designed to handle the of the client circuit can extract detected signals and so the level about the condensation water tank can detect.

4 shows a further embodiment of a sensor device according to the invention. The sensor device here has a server electrode 11 and two client circuits on. The coupling-in electrodes 21 and 21a are at the same height each near the server electrode 11 arranged so that through the server electrode 11 provided by the server circuit alternating electric fields in the coupling electrodes 21 respectively. 21a can be coupled. The decoupling electrode 22 respectively. 22a The two client circuits are also here compared to the coupling electrodes 21 respectively. 21a designed broad, so that an optimal ground coupling of the coupling-out 22 respectively. 22a is reached.

The signals provided by both client circuits (which are provided as long as the level of liquid in the container, the coupling electrodes An 21 respectively. 21a has not reached) are evaluated by the server circuit or by the evaluation of the server circuit.

In a preferred embodiment, the server circuit or the client circuits are configured such that the server circuit can distinguish the signals of the individual client circuits. For this purpose, each of the client circuits may comprise a comparator which compares, for example, an identification number modulated by the server circuit with the electrical field generated by it for a comparison identification number, each client circuit being assigned a unique comparison identification number. Because of the comparison identification number associated with the client circuits, each client circuit may use it to generate a signal including the identifier of the client circuit. As already described at the outset, these signals are transmitted to the server circuit by means of load modulation, the signals which differ on the basis of the comparison identification number effecting a different load modulation on the server circuit. The thus transmitted signals of the individual client circuits, which form a frequency mix while transmitting simultaneously, can be used by the evaluation device of the server 12 be separated and evaluated for example by means of a Fourier transform.

The Client circuits can alternatively also be designed so that they are only activated if the modulated on the electric field of the server circuit Identification number with the number of the comparison identification the client circuit matches. This will be the possibility provided that the server circuit individual client circuits the sensor device can address specifically.

In an alternative embodiment a timer can be provided instead of a comparator wherein the timers of the respective client circuits in a predetermined order and duration the client circuit activate, so that only one client circuit is active at a time.

In a further alternative embodiment can the client circuits instead of a comparator also respectively provide a free running oscillator, wherein the frequency of the different oscillators. Through the different frequency The individual oscillators are the client circuits from the server circuit distinguishable.

In In yet another alternative embodiment, the Client-circuits have a frequency divider instead of a comparator, which divides the frequency of the oscillator of the server circuit, the division ratio of individual frequency divider is different. Again, the different serves Frequency of each client circuits that the server circuit the individual client circuits can differ.

Due to the arrangement of the coupling electrodes 21 respectively. 21a the two client circuits at the same height or horizontally next to each other, this sensor device, as in 5 shown schematically, also be used to detect in addition to the filling level in the container and a possible inclination of the container. Reaches the level in the container only one of the two arranged at the same level Einkoppelelektroden 21 respectively. 21a This can be evaluated or interpre by the sensor device as a tilting of the container be turned off because only one of the two client circuits turns off in the tilted state due to the low voltage drop between the two client electrodes.

in the not tilted state would have Both client circuits turn off almost simultaneously, with to avoid misinterpretation by the evaluation a certain time interval can be provided within which the Shutdown of both client circuits must be detected in order to from the conclusion to form that, in fact to a liquid level exceeded is not a tilting of the container. By providing a such time interval can For example, Fehlauswer lines are prevented, which by about Moving the liquid due to the filling process can be caused.

Of Further or alternatively, the level difference can also the respective client circuits are used to determine the whether it is a tilted container or a non-tilted one container is.

By in the 4 proposed arrangement of the electrodes can also be determined, in which direction the container has been tilted. For example, the evaluation device of the server can determine that the container has been tilted to the left, as well as off 5 apparent - the client circuit with the electrodes 21 and 22 itself turns off and the server thus only a signal of the further client circuit with the electrodes 21a and 22a receives.

6a schematically shows a circuit arrangement according to the invention for a server circuit. A power source 71 ensures the supply of electrical energy, eg. B. as a constant current. This will be an oscillator 72 operated, which can generate an AC voltage. This alternating voltage can be fed to a mixer (not shown here), wherein this mixer additional data for sensor control, for example, the above-mentioned identification numbers, can be supplied. From the thus mixed signal, an electric field is then generated, which via the server electrode 11 is delivered. The oscillator 72 can be a limiter 73 , For example, a resistor, be downstream in order to allow any flowing currents, such as short circuit, not to grow beyond a certain level. On the other hand, the modulation (load modulation) generated by the client circuits is fed to this element to an evaluation device, which essentially consists of a filter 74 , an amplifier 75 and an evaluation unit 76 consists.

In order to emit the electric field or to receive the modulation of the client circuits, there is at least one server electrode 11 provided, which may consist of a film-like structure, for example, and can be printed directly on a film.

6b schematically shows a circuit arrangement according to the invention for a client circuit. Since the client circuit of the sensor device according to the invention is capacitively coupled to the server circuit, determines the size of the surface of the coupling electrode 21 and the server electrode 11 or the distance from one another the input energy from that of the coupling-in electrode 21 recorded alternating field. That via the coupling-in electrode 21 recorded alternating field is using a voltage transformer 81 converted into a DC voltage. This can be done for example by a diode cascade, in addition to the rectification in addition to generate a correspondingly high operating voltage from the input signal. This voltage becomes a modulator 82 operated. According to the input voltage, the modulator has 82 a certain level, with which the AC voltage can be modulated. By means of a suitable conversion of physical action variables, for example the level in the container to be monitored, it is possible to change the level of this voltage such that it can be evaluated as a function of the physical action variables on the server and thus a measure of the acting variable forms. As a result, the sensor device also makes it possible to detect not only the switching off of the client circuit according to the invention but also to monitor or evaluate a steady increase in the liquid level.

According to the present Invention, activation of the client circuit is always if a sufficient field strength (which is provided by the electric field of the server circuit is), which is in the case of a sensor device for detection the level in a container according to the present Invention simultaneously as "sensor OK" signal can be evaluated. Failure of such a signal can from the sensor device as reaching a predetermined level in a container be evaluated or interpreted.

According to the present Invention, the sensor device may include a plurality of such client circuits which of the provided by the server circuit or output electric field can be reached, so that the Power client circuits.

To several such client circuits in Within a sensor device to make distinguishable by the server circuit, the client circuit may provide a comparator, a timer, a free-running oscillator or a frequency divider. Comparator, timer, free-running oscillator or frequency divider are in 6b with the reference number 83 Mistake.

The comparator can compare an identification number modulated by the server with the alternating electric field with a comparison identification number stored in the client circuit, and only if the client circuit or the modulator is matched 82 of the client. In this way all client circuits located in an electric field can be individually addressed. If the identification number matches the comparison identification number, the selected client circuit would modulate its measured values, for example the filling level in a container, onto the carrier signal and transmit it to the server circuit via load modulation as long as the identification number matches the number of the comparison identification. Instead of modulating a value onto the carrier signal, the carrier signal can also be transmitted to the server solely by means of load modulation, which corresponds to the aforementioned "OK signal".

If the identification number on the alternating electric field provided by the server changes, the identification is lost and the comparator can cause the oscillator to stop oscillating, thus depriving the power for operating the client circuit. In this case, the evaluation device of the server circuit must check whether it receives a signal transmitted by the selected client circuit by means of load modulation of the server circuit in response to the transmitted with the electric field identification number. If there is no such an answer, the server circuit can interpret this to mean that the liquid level in the container is already the coupling-in electrode 21 has reached, which causes the voltage drop between the coupling electrode 21 and the coupling-out electrode 22 has fallen below a certain value, which is no longer sufficient for the operation of the client circuit.

As an alternative to the comparator, the client circuit can also provide a timer, which is intended to let the client circuit operate only after a certain time after receiving an electric field of the server circuit or to make the oscillator oscillate. This provides the possibility that the server circuit can receive time-matched sensor signals from different client circuits. Again, the effect occurs that, as soon as the liquid in the container to be monitored, the height of the coupling electrode 21 has reached, the oscillator no longer starts, even if due to the setting of the timer this would have to start. The server circuit may in turn interpret this as reaching the predetermined level of liquid in the container to be monitored.

alternative can also be provided a free-running oscillator. At this embodiment, It is advantageous with the individual free-running oscillators to run at a different frequency.

Instead of a freewheeling oscillator may also provide a frequency divider which divides the frequency of the oscillator of the server circuit. Preferably is the division ratio different in the individual client circuits, so the client circuits each working with different frequency.

The in the case of using a free-running oscillator or a Frequency divider simultaneously transmitted to the server circuit Signals of the individual client circuits can be so due to the different Frequencies are separated from the server again. The separation can be about using a Fourier transform.

The client circuit and at least the server electrode 11 can be applied to polymer films by printing technology, so that different forms of the sensor device can be obtained.

The decoupling electrode 22 the client circuit is (capacitively) grounded to provide a closed loop AC circuit between the server circuit and the client circuit.

Claims (19)

Sensor device for detecting the filling level in a container, comprising: at least one client circuit ( 23 . 80 ) for generating signals; and a server circuit ( 12 . 70 ) for detecting the signals generated and output by the at least one client circuit and generating an electric field; wherein - the at least one client circuit comprises a first electrode ( 21 ) and a second electrode ( 22 ) having; - The at least one client circuit is coupled based on a modulated alternating field to the server circuit; and - The at least one client circuit is supplied with the power generated by the server circuit electric field with energy for operating the client circuit. Sensor device according to claim 1, wherein the server circuit has at least one electrode ( 11 ) and wherein the at least one client circuit is capacitively coupled to the server circuit. Sensor device according to claim 2, wherein the electrodes ( 21 ) and ( 22 ) of the client circuit and the electrode ( 11 ) of the server circuit are designed band-shaped and are arranged substantially parallel to each other. Sensor device according to claim 2 or 3, wherein the distance of the first electrode ( 21 ) (Coupling-in electrode) to the electrode ( 11 ) is smaller than the distance of the second electrode ( 22 ) (Decoupling electrode) to the electrode ( 11 ). Sensor device according to one of claims 2 to 4, wherein the electrode ( 21 ) of the at least one client circuit and the electrode ( 11 ) of the server circuit narrow in relation to the electrode ( 22 ) of the client circuit are configured. Sensor device according to one of the preceding claims, wherein the at least one client circuit and the server circuit a film label, preferably printed on a polymer film, are arranged. Sensor device according to one of the preceding claims, wherein the power supply for operating the client circuit by the voltage drop between the first electrode ( 21 ) and the second electrode ( 22 ) is accomplished. Sensor device according to one of the preceding claims, wherein the power supply of the at least one client circuit is interrupted as soon as the voltage drop between the first electrode ( 21 ) and the second electrode ( 22 ) falls below a predetermined value. Sensor device according to one of the preceding claims, wherein the voltage drop between the first electrode ( 21 ) and the second electrode ( 22 ) drops below a predetermined value as soon as the level in the container of the vertical arrangement of the first electrode ( 21 ), the first electrode ( 21 ) vertically above the second electrode ( 22 ) is arranged. Sensor device according to one of the preceding Claims, wherein the sensor device is arranged in operation on the outside of the container. Sensor device according to one of claims 6 to 9, wherein the film sticker during operation of the sensor device the outside arranged the container is. Sensor device according to one of the preceding Claims, wherein the level of detection by the vertical arrangement of the sensor device on the container is determinable. Sensor device according to one of the preceding Claims, the server circuit further includes a power supply, an oscillator and an evaluation device, wherein the oscillator of the power supply is operated and wherein the evaluation device the modulated provided by the at least one client circuit Alternating field supplied becomes. Sensor device according to one of the preceding Claims, wherein two or more client circuits are configured that these are distinguishable by the server circuit. Sensor device according to claim 14, wherein the two or multiple client circuits each have a comparator, which one of the server circuit on the generated by this electric field modulated identification number with a comparison identification number compares. Sensor device according to claim 15, wherein the client circuit can only be activated if the identification number of the comparison identification number and each client circuit has a different comparison identification number is assignable. Sensor device according to claim 14, wherein the two or multiple client circuits each having a timer and wherein the timers the respective client circuits in a activate predetermined order and duration. Sensor device according to claim 14, wherein the two or multiple client circuits each have a frequency divider, for dividing the frequency of the oscillator of the server circuit, wherein the division ratio each client circuit is different. Sensor device according to claim 14, wherein the two or multiple client circuits each have a free-running oscillator have, wherein the frequency of each oscillator is different.