EP2421422B1 - Sanitary dispenser having capacitive sensor - Google Patents

Description

The invention relates to sanitary dispensers, in particular paper or towel dispensers, according to the preamble of claim 1. Especially in public sanitary facilities many efforts are made due to increased hygiene requirements to improve the prevailing hygiene and prevent or at least reduce germ transmission. To reduce the transmission of germs through the hands by touching various objects in sanitary facilities are already non-contact toilet flushing, soap dispensers, urinals, hand dryers u. Like. in use. To operate them non-contact sensors are used, mainly optical or magnetic sensors come to train.

Another category of non-contact sensors are capacitive proximity switches, wherein a sensor capacity is changed by approaching a body part, for example a human hand, or other objects, the associated electric field and thus also the sensor capacity. This change is evaluated electronically and triggers a pulse to actuate the respective device. An advantage of these capacitive proximity sensors is their independence from spatial events, such as the lighting conditions, which are of crucial importance for an optical sensor.

In the EP 0 994 667 a paper dispenser is shown having an output device actuated by a capacitive proximity sensor, the sensor capacitance being from a conventional plate capacitor having two planar electrodes is formed within the housing wall. A disadvantage here is that the weak electrical edge field of the two electrodes is only slightly changed by the approach of a human person, so that the sensor is only slightly sensitive. The triggering of the dispenser unit therefore only takes place when the user's hand is moved into a very narrow area around the sensor.

The DE 34 00 575 shows a sanitary dispenser with a capacitive proximity switch having a sensor plate. In this case, two oscillators which oscillate substantially synchronously in the rest position are provided, wherein the oscillation behavior of at least one of the oscillators can be changed by a capacitance change of the proximity switch, so that the output unit is activated at a certain oscillation difference of the oscillators.

The DE 203 20 332 shows an electronic fluid storage, which is controllable by means of a non-contact capacitive sensor.

The object of the invention is to provide a sanitary dispenser having a non-contact sensor which avoids the above disadvantages and, as far as possible uninfluenced by extrinsic influences upon approach of a human body part, sanitary means, e.g. Paper towels, towels, soap or soap foam and the like. In a dispensing opening of the housing by means of an output unit which is electrically operated, provides.

The object is achieved by a sanitary dispenser with the features of claim 1.

The capacitive sensor of the towel dispenser according to the invention forms a sensor capacitance with an approaching human body part, wherein a flat electrode is disposed inside the housing and the second conductor arrangement, to which the sensor capacity refers, through the conductive surface of a body part and additionally or alternatively an object, the is arranged in the housing exterior is formed. That is, the sheet electrode and the approximate body part act like the two plates of a plate capacitor. In particular, the sensor capacity refers in the absence of a human Body part on the capacitance between the arranged as a sensor surface in the housing interior flat electrode and the potential of the environment, so for example the earth's surface or one of the walls or the floor of the room, wherein the sanitary dispenser according to the invention is arranged.

If a human body part, for example a human hand approaches the sensor surface, that is to say the planar electrode, this sensor capacitance changes. The dispensing unit or the electric motor of the dispensing unit of the sanitary dispenser is then activated via an evaluation unit.

It can also be provided that the sanitary dispenser is designed to be electrically insulated, in particular when the electric motor of the dispensing unit is powered by one or more battery (s) and has no direct electrical connection to an external potential, i. has no grounding.

In the case of an approach of a body part and a charging of the planar electrode, these form the countercharged parts of a capacitor, i. the body part forms the second electrode of a capacitor. In particular, it can also be provided that the capacitive sensor forms only one pole in the interior of the housing in the charged state and no electrically oppositely charged surface is provided inside the housing.

If there is no body part in the detection range of the capacitive sensor, the sensor capacitance C _{s is given} by the planar electrode inside the housing and by the materials located in the vicinity of the sanitary dispenser and therefore represents a basic capacitance C _P , which is also called parasitic capacitance. This parasitic capacitance is exposed to external influences and therefore not constant. In particular, the ambient temperature, the humidity and contamination of the sanitary dispenser, which in sanitary facilities, where the sanitary dispenser according to the invention is preferably applicable play a major role, so that their changes cause a different relative permittivity ε _R , which in turn changes the parasitic capacitance C _P , However, these environmental influences cause a relatively slow change in the parasitic capacitance, since the ambient temperature and the humidity do not change abruptly. That I For reasons of installation otherwise only materials with a low relative permittivity ε _R are located in the vicinity of the capacitive sensor, the influence of the variable external variables, eg the humidity and the ambient temperature, is clearly noticeable.

If a body part, for example the hand, of a user now approaches the sensor area of a sanitary dispenser according to the invention, an additional capacitance C _H arises between the planar electrode and the approaching object. The sensor capacitance C _S , which is the total capacitance measured by the capacitive sensor, therefore forms as an additive sum of the capacitance C _{H produced} by the approaching body part and the parasitic capacitance C _P.

It should be noted that even with isolated sanitary dispensers that have no grounding, an indirect electrical connection, realized by a capacity between the potential of a body part of the user of the sanitary dispenser and the sanitary dispenser, can arise. This creepage currents are induced in the sanitary dispenser and / or in the human body, which represent an ohmic resistance R _K , which includes, among other things, body resistance, skin resistance, contact resistance of the shoes to the ground, surface or material resistances of the soil to the wall and the environment and a variety composed of material resistances and contact resistance of the sanitary dispenser and can be modeled by a plurality of series and parallel resistors. In addition, coupling fields are induced which produce a capacitance C _K. Overall, areas that are electrically conductive can be considered as a connection to electrical resistors, while spaced, ie non-connected area areas can be considered as capacitors. However, this capacitance formed by coupling fields is already implemented in the additional capacitance C _H or in the parasitic capacitance C _P.

The fact that only a planar electrode can be provided inside the housing and that the electric field of the sensor capacitance is located largely in the housing exterior or is aligned therewith, the triggering or activation of the output unit is significantly improved over the prior art in that it Sensor has a higher sensitivity and For example, an approximate human hand not only causes an output of a sanitary agent in the immediate vicinity of the capacitive sensor. It generally holds true that the larger the surface area of the sensor, the wider this effective range is.

Further advantageous embodiments of the invention are defined in the dependent claims.

In a particularly preferred embodiment of the invention, it is provided that the planar electrode is formed by a continuous metal layer, for example made of copper or aluminum.

In the formula for a plate capacitor consisting of two parallel plates with surface area A, which are arranged at a distance d from each other, the capacitance C is directly proportional to the surface A and indirectly proportional to the distance d. Generalized to the capacitive sensor according to the invention, the sensor capacitance is formed by the planar electrode and in the case of activation of the output unit by the surface of an approximate or approximate body part, this means that the additional capacitance C _H proportional to the surface area of the flat electrode and the Surface of the body part is. The larger the area contents, the greater the change in the sensor capacitance C _S due to the addition of C _H , when a body part of a user approaches the sensor area of the capacitive sensor. In a preferred embodiment of the invention, therefore, the planar electrode is greater than 15 cm ² , preferably greater than 25 cm ² , for example 30 cm ² .

According to the invention it is provided that the planar electrode is arranged at least substantially parallel to the housing wall, wherein it is further provided that the planar electrode is arranged on the front side of the housing. This ensures that the electric field emanating from the sensor surface emerges mainly vertically forward from the housing interior into the housing exterior.

In the event that the housing is at least partially cylindrical, it may be advantageous that the planar electrode is at least partially adapted to this curved shape of the housing. It may be provided that the planar electrode is formed at a constant distance in the interior of the housing with the substantially same curvature as the housing. Preferably, the planar electrode is arranged in the region of a front dispenser opening, where the sanitary agent is dispensed. In the case of a paper or towel dispenser, this may be a donor edge, which is an elongated and optionally slot-shaped opening in the housing. For a soap or soap foam dispenser, the dispenser opening may also be a tubular opening.

The arrangement in the region of the housing front wall or the housing front side takes into account the main direction of approach of a body part, as e.g. to move users' hands from the front of the sanitary dispenser, or to move past the dispenser laterally, and to further enhance the sensitivity to trigger the dispenser. The arrangement in the vicinity of the dispensing opening further improves this advantage, since a human hand, which wants to draw a sanitary agent from the sanitary dispenser according to the invention, will move mainly in the direction of the dispenser opening.

In a preferred embodiment of the invention, the sensor surface, ie the planar electrode, is part of a resonant circuit and is repeatedly charged to a potential in order then to discharge again via a resistor R _d . This resistor can be a single resistor or a system of resistors. The dimensioning of R _d is adapted to the size of the planar electrode.

In a preferred embodiment, this resonant circuit is a so-called tilt oscillation oscillator, which is also known as a relaxation oscillator. In this case, by means of simple electronic components, such as a comparator and flip-flops, constantly comparing the state of charge of the flat electrode with an internal reference voltage, the charging is always changed from charging to discharge and vice versa, when the state of charge of the planar electrode, ie whose potential exceeds or falls below a certain value. At these points, therefore, the loading or unloading process tilts.

Particularly preferably, it is provided that the Kippschwingungsoszillator includes exactly one comparator. By means of such a tilting oscillation oscillator only a few electrical components are required, whereby the production is cheaper and the susceptibility to defects decreases. It may be provided that the comparator is already integrated in a microcontroller. It may further be provided that the comparator has an inverted output. The reference voltage, which is applied to one of the inputs of the comparator, can be tapped for example on the microcontroller.

In a preferred embodiment, the invention comprises an evaluation unit which determines the time change of the sensor capacitance ΔC _S / Δt by means of the values measured by the capacitive sensor. For this purpose, it can be provided that the evaluation unit has an electronic timer, that is to say a counting unit, which, like the comparator, can be integrated in a microcontroller. Since the charging and discharging processes of the planar electrode are very short and the evaluation unit can evaluate the values transmitted by the capacitive sensor very quickly, the time interval Δt is so small (in the range of nanoseconds to microseconds), so that essentially a differential capacitive change Is evaluated. This means that the basic value of the sensor capacitance, ie the parasitic capacitance is practically negligible and their temporal changes, which result from external influences, such as by temperature fluctuations or contamination of the sanitary dispenser, have no effect, precisely because the related differential change in capacity negligible is.

In a preferred embodiment of the invention, it is further provided that the time required for the charging and / or the discharge of the planar electrode to a specific potential is compared with a reference time. In this case, the evaluation unit may have an internal clock and / or a further timer, which may also be integrated in the microcontroller. It can further be provided that not the charging and / or the discharge time itself is measured quantitatively, but is only evaluated whether this time is greater or less than a reference time. For when a human hand approaches, the sensor capacitance C _S increases and the charging and / or discharging time, ie the duration of an entire charging cycle, increases. will be raised. Again, this does not evaluate the capacity itself but the change in capacity within a certain time interval. If, as a result of the approach of a human hand, this differential change exceeds a certain value over a certain period of time (in order to exclude individual disturbing events), the output unit is activated. In this case, this limit can be defined and stored in an electronic memory.

In order to adapt to individual conditions, it is provided in a preferred embodiment of the invention that the sensitivity of the capacitive sensor is adjustable. Since the sanitary dispenser according to the invention are used in different areas, where, for example, the humidity more or less fluctuates or where the sensor area of the capacitive sensor is better or less accessible, can be adjusted by whether the output unit of the sanitary dispenser activated with a smaller or larger change in the sensor capacity becomes. It can be provided that this limit is infinitely adjustable.

In a further embodiment of the invention it is provided that the sanitary dispenser is powered by means of a battery. As a result, independent of the public power grid placement of the sanitary dispenser is possible, which in particular the subsequent installation of such a sanitary dispenser is facilitated.

The invention further relates to a method for dispensing sanitary products with a sanitary dispenser, wherein the sanitary dispenser can be designed as set forth above. The sanitary dispenser comprises a capacitive sensor and an evaluation unit, wherein the temporal change of a sensor capacitance is determined, which is formed by a planar electrode arranged in or on the sanitary dispenser and the conductive surface of a body part and / or an object which is arranged in the exterior of the sanitary dispenser is, wherein the planar electrode is arranged on the front side of the housing substantially parallel to the housing wall. An output unit arranged in the sanitary dispenser and operated by an electric motor is activated on account of the temporal change of the sensor capacity.

As a result, the capacitance itself is not evaluated, which may be problematical, in particular due to the changing parasitic capacitance C _P. Instead, the capacitive sensor and the evaluation unit only reacts to capacitive changes at specific time intervals, that is to say to temporal changes in the sensor capacitance C _S , so that a capacitive motion sensor is realized. Thereby, a distinction can be made between a change of the sensor capacitance C _S due to a slow change of the parasitic capacitance C _P and a rapid change due to the approach of a body part, and false trips due to change of the parasitic capacitance C _P can be avoided.

In order to be distinguished from a change in the parasitic capacitance C _P , the time change of the sensor capacitance C _S caused by the approach by a body part must therefore exceed a certain lower limit. In a preferred embodiment of the invention, it is provided that an upper limit for the temporal change of the sensor capacitance C _{S is} present and stored in an electronic memory in the sanitary dispenser, so that the electric motor of the output unit is activated only if the time change of the sensor capacitance C _{S is} between the upper and the lower limit. This has the advantage that due to disturbances caused by electrical devices - such as light switches, dryers, and the like - caused short and high capacity jumps are recognized by the evaluation as interference signal and false triggering, ie an output of the sanitary agent is avoided without the approach of a body part ,

Another source of problems relates to contamination by dripping on the sanitary dispenser water or soap scraps in a soap dispenser or wet papers or towels in a paper or towel dispenser. Such contamination can result in a capacity increase which is well within the above-described range between lower and upper limits. The increase in capacity caused by this, however, only fades very slowly, by draining the water from the sanitary dispenser or the soap residue from the sanitary dispenser and drying the damp paper or the damp towels. The approximation of a body part causes an increase in capacity between the very slow increase due to environmental influences - such as the increase in temperature - and sudden changes - such as by disturbances of electrical equipment - is. In general, the user's hand is directed towards the sanitary dispenser and then away from it. In between, the hand is braked. This sequence of movements initially causes an increase in the sensor capacitance C _S , which is followed by a short range with a substantially constant capacitance. Subsequently, the sensor capacitance C _S falls back to the value before the approach. Similar capacitance changes also occur when the hand is moved past the sensor area at substantially the same distance.

Since the sensor capacitance C _S has substantially the same values before and after the approach of a body part, it is provided in a preferred embodiment of the method according to the invention that the output unit or the electric motor of the output unit is activated only if the change in the sensor capacitance over time C _{S is} in the range between the upper and lower limits and additionally has substantially the same values in a time interval before and after this time change. This time interval can be between 0.2 s and 1.5 s, preferably between 0.2 s and 0.8 s.

However, it can also be provided for this purpose that the output unit is only activated when a capacity increase, which is between a lower and upper limit, a reduction in capacity takes place, the amount is also between a lower and upper limit.

As a result of these measures, the capacitive sensor or the evaluation unit can detect the difference between an interference signal and a hand approach as well as between a contamination and a hand approach. It can be provided that this time interval is also stored in an electronic memory of the sanitary dispenser. Furthermore, the upper and / or lower limit can be adjustable and / or stored in an electronic memory.

In a preferred embodiment of the method according to the invention, it is provided that a charging duration and / or a discharge duration of the electrode is or will be measured in order to determine the temporal change of the sensor capacity.

It may be advantageous that this measured duration is compared with a reference time.

Fig. 1a bis 1d

eine Draufsicht, eine Seitenansicht, einen Querschnitt sowie eine perspektivische Ansicht eines erfindungsgemäßen als Papierspender ausgebildeten Sanitärspenders,

Fig. 2

eine Vorderansicht eines erfindungsgemäßen als Papierspender ausgebildeten Sanitärspenders ohne äußere Gehäusewandung,

Fig. 3a bis 3d

eine Draufsicht, zwei Seitenansichten und eine perspektivische Darstellung eines erfindungsgemäßen kapazitiven Sensors,

Fig. 4a und 4b

eine schematische Darstellung der Funktionsweise eines Ausführungsbeispiels des erfindungsgemäßen kapazitiven Sensors mit einer Auswerteinheit und eine Darstellung der Spannungen an einem Ausgang und an einem Eingang eines Komparators des erfindungsgemäßen kapazitiven Sensors,

Fig. 5

ein Flussdiagramm zur Darstellung eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens und

Fig. 6a und 6b

eine schematische Darstellung zur Erläuterung, wann die Ausgabeeinheit eines erfindungsgemäßen Sanitärspenders aktiviert wird und

Fig. 7

einen Querschnitt eines erfindungsgemäßen als Seifenspender ausgebildeten Sanitärspenders.

Further details and advantages of the present invention will be explained in more detail below with reference to the description of the figures with reference to the drawings. It shows:

Fig. 1a to 1d

a top view, a side view, a cross section and a perspective view of a dispenser according to the invention designed as a paper dispenser,

Fig. 2

a front view of a designed as a paper dispenser sanitary dispenser without outer housing wall,

Fig. 3a to 3d

a top view, two side views and a perspective view of a capacitive sensor according to the invention,

Fig. 4a and 4b

2 shows a schematic representation of the mode of operation of an embodiment of the capacitive sensor according to the invention with an evaluation unit and a representation of the voltages at an output and at an input of a comparator of the capacitive sensor according to the invention, FIG.

Fig. 5

a flowchart illustrating an embodiment of the method according to the invention and

Fig. 6a and 6b

a schematic representation for explaining when the output unit of a sanitary dispenser according to the invention is activated and

Fig. 7

a cross section of a sanitary dispenser according to the invention designed as a soap dispenser.

In Fig. 1 a is a plan view of a sanitary dispenser 1 designed as a paper dispenser according to the invention. Here, an upper housing portion 2 is shown, for the replacement of the sanitary means 8 - in this case paper - from the rest of the housing 9 removable, or can be opened upwards. In a rear

Area are fastening means 6, such as screws, arranged so that the sanitary dispenser 1 according to the invention can be mounted on a wall.

In Fig. 1 b is a front view of the sanitary dispenser 1 is shown. In a lower region 3 of the housing 9, which does not have to be removed for replacing or refilling the sanitary means 8, a capacitive sensor 10, which has a planar electrode 11, is arranged behind a region 4 of the housing 9, ie inside the housing. Arranged behind the area 3 is an output unit 12, which conveys the paper 13 and 15 from a roll 14 through the dispensing opening 7 so that it can be removed there by a user. The area 4 is located near the dispensing opening 7. On the underside of an emergency button 5 is arranged, whose function will be explained in more detail below.

In Fig. 1 c is a cross-sectional view of the paper dispenser Fig. 1 b along the line marked AA. On a roll 14 to be donated sanitary means 8, in this case paper 13, stored. Above this, another paper roll 15 is stored as a reserve. The dispensing unit 12 comprises a roller 16, which is operated by an electric motor 17 via gears 18 and the paper 13 is conveyed through the dispenser opening 7. Behind the region 4 of the housing 9, a capacitive sensor 10 is arranged, which activates the electric motor 17 and thus the output unit 12 via a control unit 19 and thus conveys a unit of the paper 13 through the dispensing opening 7. For this purpose, a knife is arranged on the roller 16, which perforates or cuts a sheet of paper 13, for example, during each complete revolution, so that a user can easily remove it or easily tear it off. Once the dispensing unit 12 has been activated, the roller 16 continues to rotate until a piece of the next dispensing unit of the paper 13 passes through the dispenser opening 7. Is there a malfunction eg by paper jam or the output unit 12, for example, due to a malfunction of the capacitive sensor 10 is not triggered, an emergency button 5 is present, the operation of the engine 17 decoupled from the output unit 12 and manually turn the roller 16 so far that a Unit of the paper 13 can be removed.

Further details of the sanitary dispenser 1 shown are not provided with reference numerals for reasons of clarity or not shown. The dispensing unit 12 and the emergency button 5 for such a paper dispenser are known per se in the prior art and for example in the US 2007/0079684 disclosed. However, the mode of operation of the capacitive sensor according to the invention is not limited to the exemplary embodiment of a paper dispenser illustrated here but can generally be used for sanitary dispensers 1 with an electrically operated dispensing unit 12.

In Fig. 1 d is the perspective view of a sanitary dispenser 1 shown, wherein the area 2 of the housing is removed and no sanitary means 8 are arranged inside the housing. This is the situation that arises when refilling the sanitary dispenser 1.

In Fig. 2 is a front view of the housing interior of a sanitary dispenser 1 according to the invention shown. Here, the gears 18 are shown, which are on the one hand with the motor 17 and the roller 16, on the other hand with the emergency button 5 in conjunction to carry the paper 13 by means of the roller 16 through the dispenser opening 7. In the vicinity of the dispensing opening 7, the capacitive sensor 10 according to the invention is arranged inside the housing, wherein the electronics of the capacitive sensor 10s may comprise a planar electrode 11 and a microcontroller 24 with the integrated evaluation unit 19 'and the integrated control unit 19, and a switch 20 for activating the capacitive sensor 10. The electronics also have a plug-in connection with which the electronics with the motor 17, the batteries or an external power source and the like can be connected. The planar electrode 11 has an area of more than 25 cm ² , for example 30 cm ² . Thus, a large area is available so that the sensor capacitance C _S delimits itself sufficiently from the parasitic capacitance C _P when a user's hand 21 approaches the capacitive sensor 10.

In Fig. 3a is a plan view of the capacitive sensor 10, including its electronics shown. On a large part of the sensor 10, the planar electrode 11 is arranged, which is shown hatched in this case, but which consists of a continuous sheet metal layer.

With a switch 20, the electronics of the capacitive sensor 10 can be activated. This includes a microcontroller 24 with an integrated evaluation unit 19 'and an integrated control unit 19, which can also be designed as a common component. The control unit 19 transmits the control commands to the output unit 12 via connections 23 and / or plug connections 22. Via a further connection, the sensor 10 can be supplied, for example, with power and additionally or alternatively exchange control commands. In the FIGS. 3b and 3c Side views of the capacitive sensor 10 are shown with the electronics. In Fig. 3d is a perspective view of the sensor 10 is shown with the electronics, the sensor 10 is very narrow and thus easily behind the area 4 of the housing 9 can be arranged. In the case of cylindrical housing 9 but it would also be possible to form the planar electrode 11 also cylindrical. The area of the capacitive sensor 10 next to the planar electrode 11 includes the electronic components, such as the microcontroller 24 with the integrated evaluation unit 19 'and the control unit 19, as well as other adjustment elements and the connector 22. The microcontroller 24, the Fig. 3a to 3c is not explicitly shown, is known per se in the prior art and therefore need not be explained in detail.

In Fig. 4a a schematic structure of the circuit and the required hardware modules for the capacitive sensor 10 according to the invention and an illustration of the operation of the same is shown. On the left edge of the capacitive sensor 10, the planar electrode 11 is shown, which is arranged together with the surface of a hand 21 and / or an object which is outside in the housing, the sensor capacitance C _S forms. Without an approximate hand 21, the sensor capacitance C _S consists only of the parasitic capacitance C _P. By approaching a hand 21, the capacitance between the hand 21 and the planar electrode 11 C _{H is} added to this parasitic capacitance C _P so that the sensor capacitance C _S results as the sum of C _P and C _H. This change in the sensor capacitance C _S is detected by the capacitive sensor 10 according to the invention, which leads to the triggering of the output unit 12 and to the output of a sanitary means 8, that is, for example, a sheet of paper 13. Furthermore, two clamping points 53 are arranged, which are formed for example by the legs of the microcontroller 24. All within The dashed line arranged components are hardware elements of the microcontroller 24th

The positive, non-inverted input 26 of the comparator 25 is connected to the planar electrode 11 and to the cathode of the diode 28. At the negative input 27 of the comparator 25 is an internal reference voltage, which is, for example, 0.6 V DC. The inverted output 33 of the comparator is connected to the anode of the diode 28. The planar electrode 11 is discharged via the resistor R _d . The size of this resistor R _d is adapted to the size of the planar electrode 11. Due to the installation direction of the diode 28, the planar electrode 11 is charged via the diode 28. By this switching arrangement creates a so-called Kippschwingungszzillator, which is also referred to as relaxation oscillator, with exactly one comparator 25. The planar electrode 11 is part of this resonant circuit and determines its frequency by means of the time constant τ, which is generally the product of resistance and capacitance for resonant circuits ,

Now, if this circuit is supplied with voltage, the supply voltage may be in one embodiment, 5V DC voltage, the resonant circuit must first settle because present at the beginning of both inputs 26, 27 of the comparator 25 zero V. Due to the better clarity, the voltage source itself is not shown in this schematic representation. After a short time, the internal reference voltage is present at the negative input 27 of the comparator 25, the value of which may for example be between 0.4 V and 1.5 V, preferably about 0.6 V, whereas the positive input 26 is still at 0V , The comparator 25 compares the two voltages with each other and switches, due to the inverted output 33 to "HIGH", ie at the output 33 is the supply voltage, so for example 5V DC, because the difference of the voltages at the inputs 26, 27 of the comparator 25 negative is. The diode 28 is now conductive, whereby the planar electrode 11 is charged and forms a sensor capacitance C _S. Although the charging process should last only until the difference between the two applied to the inputs of the comparator 25 voltages is positive, due to the inertia of the comparator 25 (response time), the planar electrode 11 is substantially up to the supply voltage, so for example to 5V DC voltage charged, which is then just as positive Input 26 of the comparator is applied. Only then does the comparator 25 react and switch the inverted output 33 to "LOW", ie at the output 33 0V are present. The diode 28 now turns off and the planar electrode 11 begins to discharge via the resistor R _d . As a result, reduces the voltage at the positive input 26 of the comparator 25 to a value smaller than the internal reference voltage, which is applied to the negative input 27 of the comparator 25, the charging of the flat electrode 11 starts again. By this Kippschwingungsoszillator the planar electrode 11 is thus constantly charged and discharged, the charging of the electrode 11 can be done up to supply voltage and the discharge to reference voltage.

It may be provided that the charging pulses at the output 33 of the comparator 25 are only very short and the discharge time on the resistor R _{d is} slower from equip, so that a sawtooth generated by the charging of the planar electrode 11. It is essential that with constant sensor capacitance C _S, the time between the load pulses, ie the time between the switching of the comparator 25 from "LOW" to "HIGH" and vice versa is constant. Now moves an object in the vicinity of the planar electrode 11, ie in the vicinity of the capacitive sensor 10, the sensor capacitance C _{S increases} by addition of C _H , whereby the discharge process takes longer, since the time constant τ of the resonant circuit is a product of the Resistor R _d and the sensor capacitance C _{S is} given. In the sensor capacitance C _S , which was supplemented by the addition of C _H , the coupling-induced capacitance C _{K is} implemented, which are mediated by the environment of the user's hand 21 and the environment of the medical dispenser 1. Creepage currents represented by the resistor R _K flow through electrically conductive regions of this environment, while area regions which are spaced apart form capacitances which are given by the capacitance C _K as a whole. The larger the sensor capacitance C _S, the larger the time constant τ, whereby the discharge process takes longer. By virtue of this general principle, it is possible to detect a sensor capacitance C _S changing as a result of an approaching hand 21.

Furthermore, the capacitive sensor 10 has a first timer 29, via an electronic memory 30 by a software module is stored, via an internal clock 31 and a second timer 32. The internal clock 31 and the timers 29, 32 are constructed from known electronic components. These components 29, 30, 31, 32, like the comparator 25, may be integrated in a microcontroller 24, which may be part of an evaluation unit 19 ', which measures the measured values, eg the measured times for the charging duration and / or the discharge duration the flat electrode 11 evaluates and via a control unit 19 ', the output unit 12 and the electric motor 17 of the output unit 12 is activated.

In Fig. 4b The upper diagram represents the voltage over time over a plurality of charging cycles at the output 33 of the comparator 25. It can be clearly seen that the charging time, ie the charging pulses are only very short. In the lower diagram, the voltage at the input 26 of the comparator 25 over time over several charging cycles is shown. Clearly visible is the running in accordance with a time constant discharge, wherein the charging process begins in each case when the voltage falls below a certain value and the tilting oscillator thereby tilts.

In Fig. 5 a flowchart is shown how a software stored in the electronic memory 30 evaluates the measured values. After the start 33 of the evaluation which can be activated, for example, by the switch 20, the system is initialized in a step 34 and both timers 29, 32 and the comparator 25 are supplied with power. In this case, the first timer 29 is fed by the charging pulses of the comparator 25, while the second timer 32 is powered by the internal clock 31, which acts as a clock. The durations for the charging or the discharge of the planar electrode are very short, so that even during a change in value of the sensor capacitance C _S as a result of the approach of a hand 21 more charging pulses take place and several times the charging and / or the discharge time is measured. In a step 35, both timers 29, 32 are set to zero. Depending on the embodiment, these timers can count up to different highs. If twelve timers are provided for both timers 29, 32, both can count from 0 to 4,095. After this maximum value, the respective timer overflows and starts again at zero. Of course, it is also possible to use timers 29, 32 with other maximum values, ie a different bit structure.

The first counter 29, which is fed by the inverted output 33 of the comparator 25, increases its count at each rising edge of the output voltage of the comparator 25, that is, each time a charging operation of the planar electrode 11 begins. It is also conceivable that the count is increased each time the edge drops. This makes it possible to save the entire duration of a charging cycle, i. Charging and discharging the flat electrode 11 to measure. Since, however, also due to the dimensioning of the components, the charging time is many times shorter than the discharge duration, the total charging duration substantially corresponds to the discharge duration. That is, the time required for the charge is very short compared to the time required for the discharge given by the time constant τ, and therefore can be regarded as constant or even negligible. Of course, it is also conceivable to separately measure and evaluate the charging and discharging time by means of known electronic components.

If the first timer 29 reaches its maximum level, for example 4.095, it overflows and sets the overflow bit T01 F of the first timer 29 to one. In a step 37, the value of these overflow bits is continuously polled. As soon as the value has changed from zero to one, the second timer 32 is stopped in a next step 38. Since this second timer 32 is fed by an internal clock 31 and thus increases its count after predetermined by the internal clock 31 clock, the reading of the count of the second timer 32 in a step 39 provides a time value. This time value corresponds to the time for a number of charging cycles of the planar electrode 11 which correspond to the maximum value of the first counter 29, ie in this case how much time has elapsed until the planar electrode has been discharged 4,096 times. Since this duration is dependent on the size of the sensor capacitance C _S , a change in this sensor capacitance C _S, in particular a temporal change in the sensor capacitance C _S, can be detected since the evaluation unit 19 'reads the count of the second timer 32 read in step 39 in an electronic memory 30 compares with previous values or with reference values stored there. Since a charging cycle of the planar electrode 11 in the range of nano seconds to at most a few microseconds, a large number of read-out operations of the second timer 32 are possible during the approach of a hand 21, so that the resulting detectable averaged temporal change .DELTA.C _S / At of the sensor capacitance C _S in practice the differential change dC _S / dt the sensor capacitance C _S corresponds.

In Fig. 6a the course of the sensor capacitance C _S over a certain period of time is represented by the curved curve 41. The step-shaped curve 42 represents the change .DELTA.C _S. The numerical values below this curve 42 denote in a relative unit the respective increase or the respective decrease of the sensor capacitance C _S compared to the previously determined value. In Fig. 6b the curve 43 gives the control signal transmitted by the control unit 19 'to the electric motor which is represented as a binary signal. As long as this signal is at 0, no activation of the motor 17 occurs. When the control signal jumps to 1, the electric motor 17 of the output unit 12 is activated, thereby outputting a unit of the sanitary means 8 to be dispensed.

The stored in the electronic memory 30 software, it is possible that the capacitive sensor 10, however, can distinguish between a noise or pollution and only in the case of approach of a body part, the electric motor 17 is activated. In the area 44 of Fig. 6a occurs a fault by electrical equipment such as by a near the sanitary dispenser 1 according to the invention dryer, which causes a very high and short capacity jump. This erratic capacitance change of +9 and -7 units is outside of the upper and lower limits for capacity changes stored in the electronic memory 30. Only if the amount of change in the sensor capacitance C _{S is} between this upper and lower limit, tripping can take place. In principle, no tripping can take place outside this upper limit and lower limit. This disturbance thus causes no triggering.

In the area 45 of the Fig. 6a a situation is shown, which typically results from contamination of a sanitary dispenser 1 by water, damp paper or soap scraps, for example. In this area 45 there is previously a slight increase in capacity by one to three units, which in principle lies between the upper and lower limits for permissible capacity changes. In this embodiment of the invention, however, it is provided that the activation of the electric motor 17 takes place only when the sensor capacitance C _S falls back to the value before the rise within a relatively short period of time. In this area 45, however, it can be seen that the previous increase in capacity only is degraded very slowly, since the damp paper dries relatively slowly or drops of water or soap only slowly. As a result, the software stored in the electronic memory 30 may interpret this as contamination and not activate the output unit 12.

In area 46, the situation that arises when a hand 21 approaches the sensor 10 can now be seen. As a result of this approach, the capacity increases between two and three units. Thereafter, the hand 21 is braked, whereby in the region of a local maximum, the sensor capacitance C _S is substantially constant and no change of the evaluation unit 19 'is determined. Thereafter, the hand 21 again moves away from the sensor 10 slightly, for example, in the direction of the dispenser opening 7, whereby the sensor capacitance C _S decreases again. Both the changes during the capacity increase and during the capacity decrease are in the specified range through the lower and upper limits, whereby the reduction in capacity is determined by the amount. It may be provided that the software evaluates this feature as a hand approach and activates the output unit 12. In this exemplary embodiment, however, it is provided that the fact that essentially the same values for the sensor capacitance C _S occur before the increase in capacitance and after the capacitance decrease is interpreted by the software as the approach of a hand 21, so that in the region 47 of FIG Fig. 6b the output unit 12 is triggered by a control signal from the control unit 19 'activates the electric motor 17.

In Fig. 7 is a cross section of a trained as a soap dispenser sanitary dispenser 1 according to the invention. In this sanitary dispenser 1, a tank 49 is arranged with the liquid soap, via a refill 48 further sanitary agent 8, ie more soap can be transported into the tank 49. At the bottom of the housing 3, a capacitive sensor 10 according to the invention is arranged. As soon as a user's hand 21 approaches the sensor field, an electric motor activating an air pump 50 and a soap pump 51 is activated. The dispenser opening 7 is provided with a foam generator 52 which mixes the air sucked by the air pump 50 with the soap sucked by the soap pump 51, so that soap scum is discharged through the dispenser opening 7. It goes without saying that the sanitary dispenser according to the invention is not limited to the embodiments shown in the figures, nor should be limited by them. In particular, all sanitary dispensers provided with electrical actuation, such as paper dispensers, towel dispensers, soap dispensers, disinfectant dispensers, and the like, are within the scope of the following claims.

Claims (15)

1. A sanitary dispenser (1), in particular a paper-towel dispenser or a hand-towel dispenser, comprising a housing (9), in which are disposed a dispensing unit (12) for dispensing a sanitary product (8) and a capacitive sensor (10), the dispensing unit (12) having an electric motor (17) activated in a contactless manner by the capacitive sensor (10) from outside outside the housing (9), wherein the sensor capacitance (C_S) of the capacitive sensor (10) is formed by a planar electrode (11) disposed in the housing interior and a surface of a part of a body (21) being advanced up, and wherein for activating the dispensing unit (12) the surface of the part of a body (21) being advanced up and the planar electrode (11) are forming the oppositely charged parts of a capacitor, characterized in that the planar electrode (11) is disposed on the front side of the housing (9) substantially parallel to the housing wall.
2. The sanitary dispenser according to claim 1, characterized in that the planar electrode (11) is formed by a continuous metal layer.
3. A sanitary dispenser according to claim 1 or 2, characterized in that the planar electrode (11) is disposed immediately behind the housing wall, preferably in the region (4) of a front dispenser opening (7).
4. The sanitary dispenser according to one of claims 1 to 3, characterized in that the planar electrode (11) is part of an oscillating circuit, preferably of a relaxation oscillator.
5. The sanitary dispenser according to claim 4, characterized in that the relaxation oscillator has precisely one comparator (25).
6. The sanitary dispenser according to one of the claims 1 to 5, characterized in that the sanitary dispenser (1) has an evaluation unit (19') configured such that it is possible to determine a change over time in the sensor capacitance (C_S).
7. The sanitary dispenser according to claim 6, characterized in that the evaluation unit (19') is configured such that the change over time in the sensor capacitance (C_S) can be determined by measuring at least one of a charging period or a discharging period of the planar electrode (11) and comparing the same with a reference time.
8. The sanitary dispenser according to one of the claims 1 to 7, characterized in that a sensitivity of the capacitive sensor (10) can be adjusted, preferably in a stepless manner.
9. The sanitary dispenser according to one of the claims 1 to 8, characterized in that the sanitary dispenser (1) comprises a battery for power-supply purposes.
10. A method of dispensing sanitary products using a sanitary dispenser (1), in particular according to one of the claims 1 to 9, the sanitary dispenser (1) containing a dispensing unit (12) for a sanitary product (8) which can be dispensed and operated by an electric motor (17), a capacitive sensor (10) and an evaluation unit (19'), the capacitive sensor (10) having a planar electrode (11) for forming a sensor capacitance (C_S) with a surface of a part of a body (21) being advanced up, wherein the surface of the part of the body (21) being advanced up and the planar electrode (11) are forming the oppositely charged parts of a capacitor, characterized in that the planar electrode (11) is disposed on the front side of the housing (9) substantially parallel to the housing wall and a change over time in the sensor capacitance (C_S) is determined and the electric motor (17) of the dispensing unit (12) of the sanitary dispenser (1) is activated in dependence on the change over time in the sensor capacitance (Cs).
11. The method according to claim 10, characterized in that a lower limit and an upper limit for the change over time of the sensor capacitance (C_S) is stored in an electronic memory (30) in the sanitary dispenser (1) and the electric motor (17) of the dispensing unit (12) is activated only when the change over time in the sensor capacitance (C_S) lies between the lower limit and the upper limit.
12. The method according to claim 11, characterized in that the electric motor (17) of the dispensing unit (12) is only activated when, within a time interval, stored in the electronic memory (17) in the sanitary dispenser (1), before and after the change over time in the sensor capacitance (C_S) which lies between the lower limit and the upper limit, the sensor capacitance (C_S) has substantially same values.
13. The method according to claim 10, characterized in that the electric motor (17) of the dispensing unit (12) is only activated when, after an increase in the sensor capacitance (C_S) which lies between a lower limit and an upper limit, the sensor capacitance (C_S) decreases by an amount which lies between a lower limit and an upper limit.
14. The method according to one of the claims 11 to 13, characterized in that at least one of the lower limits and/or at least one of the upper limits is or are adjustable.
15. The method according to one of claims 10 to 14, characterized in that a charging period and/or a discharging period for the planar electrode (11) is detected and compared with a reference time.

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