WO2024057200A1 - Washing agent dispenser for dishwashers - Google Patents

Abstract

A washing agent dispenser for dishwashers comprises a dispenser body (20) having a front at which a receptacle (40) delimited by a plurality of walls (40a-40d) is defined, for the containment of washing agents (LD). The dispenser (1) comprises a sensor device (50) having a sensitive part which is configured for detecting electrical capacity. The sensitive part comprises one single detection electrode (Jd), arranged outside the receptacle (40) in a side by side position with respect to a first wall (40b) of the plurality of walls (40b-40d) delimiting the receptacle (40). The sensor device (50) comprises a control circuit (MC) to which the single detection electrode (Jd) is connected in signal communication, the control circuit (MC) being configured for detecting presence and/or type of a washing agent present in the receptacle (40) according to a first value representative of electrical capacity between the single detection electrode (Jd) and the washing agent present in the receptacle (40).

Description

“Washing agent dispenser for dishwashers”

DESCRIPTION

Field of the invention

The present invention refers to a dispenser of washing agents for dishwashers, and has been developed with particular attention being paid to a dispenser provided with sensor means for detecting the type of a washing agent loaded into the dispenser itself.

Prior art

Some dishwashers are provided with a dispensing device configured to dispense at least one washing agent. Generally, these devices are designed to dispense, at different times of one and the same washing cycle of the dishwasher, at least two different washing agents, typically represented by a detergent (powder, or liquid, or in tablet form) and a liquid rinsing additive. Dispensers designed for the purpose of dispensing a single washing substance in solid or liquid form are also known.

In the most common solutions, the dishwasher dispensers comprise a dispenser body associated with one of the vertical walls that delimit the washing tank of the machine (including the inner shell of the front door of the machine that is facing towards the inside of the washing tank), usually at least partially sealingly recessed in an opening provided in this wall. In the front area of the dispenser body a receptacle is defined for the containment of a washing agent, usually a washing detergent in powder form or in tablet form or in fluid form (liquid or gel), required for the execution of a washing cycle. The dispenser body, at the receptacle, has a movable door associated thereto. Elastic means are operating between the dispenser body and the door body, which urges the door towards a respective opening position, as well as a door locking/releasing system. During a washing cycle, the opening of the aforementioned door is appropriately controlled by a programmer, or timer, of the dishwasher, which controls an actuator that is part of the aforementioned locking/releasing system; the latter is usually also designed to enable, with the machine not in operation, the manual opening and closing of the door.

As mentioned, the washing agents that can be used on a dishwasher can be of different types, for example in liquid form, or in powdery form, or in the form of compacted tablets, or even in the form of tablets or capsules - also known as "tabs" or "pods" - in which one or more washing agents in liquid or semi-solid form are enclosed in a casing formed by a water-soluble film (typically a polymer, such as polyvinyl acetate - PVA).

Since these different types of washing agents have different characteristics, it may be convenient to optimize a treatment program that can be carried out by the dishwasher according to the type of washing agent actually used. In other words, a treatment program designed for a washing powder may not be perfectly suitable for the use of a liquid detergent or in tablet form. For this reason, in some known solutions, the type of washing agent used from time to time is detected, so that the dishwasher control logic is able to choose a program, or at least a program parameter, considered most suitable for the type of washing agent detected.

Regardless of the type of washing agent, even the simple detection of its presence in the corresponding receptacle can be useful, for example if the control logic of the dishwasher is programmed to prevent the carrying out of a washing program when the presence of a detergent is not detected in the receptacle itself (for example due to a forgetfulness of the user).

In some solutions, the detection is carried out after the opening of the receptacle door, i.e., after the (theoretical) dispensing of the washing agent into the tank of the machine. In these solutions the presence (or absence) and/or the type of washing agent is generally identified by sensor means that detect one or more characteristics of the washing liquid present in the tank, i.e., the water-washing agent mixture. These characteristics may concern electrical quantities (for example conductivity), or optical quantities (for example turbidity) or chemical quantities.

In other solutions, the detection of the type of washing agent is carried out directly within the dispenser, which is equipped with appropriate sensor means.

FR 2940037 A discloses a washing agent dispenser provided with a receiving area for a washing agent, to which a capacitive sensor is associated. The sensor includes two opposite electrodes, arranged around the aforementioned receiving area, and is designed to detect the presence and the type of washing agent contained in this area. More specifically, the two electrodes are arranged along two opposite walls that delimit the receiving area, and in fact realize two electrically insulated metal armatures of a flat capacitor.

The capacitive detection proposed by FR 2940037 A is based on the fact that the value of the equivalent capacity of the washing agent possibly present in the dispenser is directly proportional to its electrical permittivity. On this basis, the proposed sensor makes it possible to detect whether a washing agent is present in the receiving space between the two electrodes (or not) and, if present, its type between a powdery detergent, a detergent in tablet form, a liquid or gel detergent.

The solution described in FR 2940037 A is structurally complicated, as it requires that the receiving area of the washing agent is set between the two electrodes, with possible complications in terms of assembly, dimensions and electrical connections.

The capacitance measurements that can be obtained by the sensor according to FR 2940037 A can also be adversely affected by various factors, such as environmental stresses, like temperature, humidity, aging, electronic/electromagnetic noise, resulting in poor reliability, particularly in the long term. Also the possible presence of water residues in the aforementioned receiving area, following a previous washing cycle in the dishwasher, can also be a source of detection errors.

Aim and summary of the invention

In its general terms, the present invention aims to solve one or more of the aforementioned drawbacks. In this context, the present invention aims to obtain a dispenser provided with a capacitive-type sensor device, suitable for detecting the presence and/or the type of a washing agent, of a simple and economic construction, as well as precise and reliable in operation.

This and other aims, which will become clearer later, are achieved according to the present invention by a dispenser of washing agents having the characteristics of the attached claims. The aims of the invention are also achieved by a method and a sensor device for detecting the presence and/or the type of a washing agent in a receptacle of a dishwasher dispenser, as well as by a dishwasher that includes such a dispenser, or a dispenser that includes such a sensor device. The claims form an integral part of the technical teaching provided herein in connection with the invention.

In accordance with a first embodiment of the invention, a washing agent dispenser for dishwashers comprises a dispenser body and a door, wherein the dispenser body has a front at which a receptacle for the containment of washing agents is defined, which is delimited by a plurality of walls, wherein the door is mounted movable on the dispenser body, to be displaceable between a closing position and an opening position of the receptacle, wherein the dispenser comprises a sensor device having at least one sensitive part which is configured for detecting electrical capacity, wherein the at least one sensitive part comprises at least one single detection electrode, arranged outside the receptacle in a contiguous or side by side position with respect to a first wall of the plurality of walls delimiting the receptacle, and wherein the sensor device comprises a control circuit to which the single detection electrode is connected in signal communication, the control circuit being configured for detecting presence and/or type of a washing agent present in the receptacle according to a first value representative of electrical capacity between the single detection electrode and the washing agent present in the receptacle.

In accordance with the invention, the definition "single electrode" is meant to indicate a first electrode or armature of a capacitive element that does not require a second opposed electrode; even in the case of a plurality of single electrodes, each first single electrode or armature does not require a respective opposed second electrode.

The capacitive sensor device has structure which is simple, compact and easy to be housed on the body of the dispenser, without the need to provide two distinct opposed detection electrodes, which obtain two armatures of a capacitor.

As it will be seen, in fact, a proposed detection mode enables to detect the presence (or absence) and/or the type of a washing agent on the basis of an electrode, which obtains the sensitive armature of a capacitor; the other armature can be defined as "virtual", as it is represented by the same washing agent contained in the receptacle.

In various embodiments, the dispenser comprises at least one compensation arrangement, for compensation of the first value representative of electrical capacity. In this way, if necessary, it is possible to have a representative value of electrical capacity that is compensated for example according to environmental and aging conditions of the sensor device, as better explained below, for the purpose of a greater detection accuracy.

The cited compensation arrangement may comprise at least one reference electrode, arranged in a position which is not contiguous or side by side with respect to the walls of the plurality of walls delimiting the receptacle, and connected in signal communication to the control circuit. In this way, the reference electrode is substantially subjected to the same environmental and aging conditions of the sensor device, and is not influenced by the washing agent.

Preferably, the control circuit is thus configured for compensating the first value representative of electrical capacity as a function of at least one further value representative of electrical capacity acquired via the at least one reference electrode. To this purpose, preferably, the control circuit is configured to perform a correlation and/or a differential measure between the first value representative of electrical capacity and the further value representative of electrical capacity, in order to obtain a compensated value representative of electrical capacity.

In various embodiments, the cited the compensation arrangement comprises a temperature detector. This solution is useful if it is desired to take into account the incidence of the temperature on the detections of capacitive type.

In various embodiments, the control circuit is configured to compare the first value representative of electrical capacity, or a first compensated value representative of electrical capacity, with at least one corresponding reference threshold, to deduce presence and/or type of a washing agent contained in the receptacle.

Preferably, the control circuit is configured to compare the first value representative of electrical capacity, or the first compensated value representative of electrical capacity, with a plurality of reference thresholds, to deduce the type of washing agent possibly contained in the receptacle between a liquid washing agent, a powder washing agent, a washing agent in tablet or capsule form.

In various embodiments, at an inner side of the first wall of the receptacle, at least one spacing element is provided, suitable for keeping a washing agent in the form of a tablet in a position spaced apart from the same inner side of the first wall. In this case the aforementioned tablet can be kept in the receptacle in a position more distant from the single detection electrode, compared to washing agents in bulk form (in powder or liquid), with a consequent attenuation of the first value representative of electrical capacity: this allows to discriminate more easily between a tablet and a bulk washing agent, in particular when the tablet is formed with a material similar to that of the bulk washing agent.

Advantageously, the single detection electrode and the control circuit, that is preferably in the form of a microcontroller, are on one and the same circuit support which is mounted on the dispenser body. In this way, mounting of the sensor device is further simplified. Also the cited compensation arrangement (reference electrode and/or temperature detection) can be mounted on said circuit support, to further advantage concerning compactness of the sensor device in the assembling thereof in the operating position. The possibility of obtaining on one and the same support the at least one single detection electrode and at least one of the control circuit and the compensation arrangement (at least one single reference electrode and/or a temperature detector) enables an easy assembling with respect to a first wall of the plurality of walls which delimit the receptacle.

In various embodiments:

- the control circuit has at least one signal input to which the single detection electrode is connected (or else the at least one reference electrode), with the same signal input which is also connected or connectable to a circuit including a controllable switch, such as an electronic switch, and a capacitor, the controllable switch being switchable between a first position, in which the capacitor is connected to a voltage source, and a second position, in which the capacitor is connected to the at least one signal input, and

- the control circuit is configured to switch the controllable switch from the first position to the second position, to cause a discharge of the capacitor in a way proportional to the first value representative of electrical capacity (or else the further value representative of electrical capacity), associated with the at least one signal input.

In this way, by means of a simple sampling circuit, in particular of the Sample and Hold type, the first value representative of electrical capacity can be detected (and, if the compensation is provided for, the further value representative of electrical capacity). Such a circuit - or any other technically equivalent circuit for the purpose of detection of a capacitance - is usually implemented within a commercial microcontroller which can obtain the control circuit.

Preferably, the at least one single detection electrode has an area such as to affect only a lower or intermediate portion of the receptacle, for the purposes of a mor reliable detection. The single detection electrode and the at least one reference electrode can be substantially coplanar.

In various embodiments the sensor device also comprises an auxiliary control electrode in a position close to the single detection electrode, which is connected or selectively connectable to the control circuit, in particular in order to attenuate possible disturbances deriving from the presence of water residues within the receptacle. This measure enables, for example, to avoid detection errors when within the receptacle water residues are present, deriving from the carrying out of a preceding washing cycle performed by the dishwasher. Brief description of the drawings

Ulteriori scopi, caratteristiche e vantaggi della presente invenzione risultano chiari dalla descrizione particolareggiata che segue, effettuata con riferimento ai disegni schematici annessi, forniti a puro titolo di esempio non limitativo, nei quali:

Further aims, characteristics and advantages of the present invention will be clear from the following detailed description, made with reference to the attached schematic drawings, provided purely as a non-limiting example, in which:

- figure 1 is a schematic front perspective view of a washing agent dispenser according to possible embodiments, with a respective door in closed condition;

- figure 2 is a schematic rear perspective view, partially sectioned, of a washing agent dispenser according to possible embodiments;

- figures 3 and 4 are schematic front perspective views of a washing agent dispenser according to possible embodiments, at two different angles, with a respective door in open condition;

- figure 5 is a schematic side perspective view, partially sectioned, of a dispenser of washing agents according to possible embodiments;

- figures 6 and 7 are schematic perspective views of two possible versions of a sensor device of a washing agent dispenser according to possible embodiments;

- figures 8 and 9 are schematic front perspective views of a washing agent dispenser according to possible embodiments, with a respective door in open condition, and with two different washing agents contained in a corresponding receptacle;

- figure 10 is a schematic representation aimed at exemplifying a first possible circuit arrangement and a principle of operation of a sensor device of a dispensing device according to possible embodiments;

- figure 11 is a schematic representation intended to exemplify a second possible circuit arrangement of a sensor device of a dispensing device according to possible embodiments;

- figures 12-14 are schematic representations similar to those of figure 11, in relation to different types of washing agents; and

- figures 15 and 16 are schematic representations intended to exemplify a further possible circuit arrangement and a corresponding principle of operation of a sensor device of a dispensing device according to possible variants embodiments.

Description of preferred embodiments of the invention

The reference to "an embodiment" within this description indicates that a particular configuration, structure, or characteristic described in relation to the embodiment is included in at least one embodiment. Thus, phrases such as "in an embodiment " and the like, possibly present in different places in this description, do not necessarily refer to the same embodiment. In addition, particular conformations, structures or characteristics can be combined in any appropriate way in one or more embodiments, even different from those depicted. The references used here are for convenience only and therefore do not define the scope of protection or the scope of the embodiments.

Referring initially to figures 1-4, reference 1 designates as a whole a dispenser of washing agents according to possible embodiments of the present invention. In the specific case exemplified, the dispenser 1 is intended for use on a dishwasher machine, and is configured to be mounted on a wall of the corresponding washing tank, although this is not an essential feature. For example, the mounting wall can be defined by the inner shell of a dishwasher door, with the dispenser 1 being fixed to the side of this shell which faces the inside of the tank during machine’s operation.

The dispenser 1 comprises a dispenser body 20, which is preferably formed at least partly with moulded thermoplastic material. The body 20 is preferably configured to be at least partially recessed into an opening provided in the aforementioned mounting wall. In the example shown, the body 20 has a generally quadrangular peripheral profile, although this is not an essential feature. The sides indicated by 20a and 20b of the peripheral profile of the body 20 are herein conventionally referred to as "upper side" and "lower side", in relation to a preferential orientation of the dispenser 1 in its operational position, as shown for example in figures 1 and 2. In the case of mounting on the dishwasher door, then, in the closed-door condition, the side 20a will be located higher than the side 20b.

The body 20 may comprise a front piece or part, suitable to face to, or be located into, the washing tank, and a rear piece or part, suitable to be at least partially inserted into the aforementioned opening of the mounting wall, the two parts being conveniently moulded with thermoplastic material separately from each other and then joined together, for example by welding, according to a technique known in itself. The two parts can define therebetween at least one of the body 20.

In the example, the front part of the body 20 defines a front of dispenser 1, intended to face, or be located into, the washing tank, and which has at least one door associated thereto, designated as a whole by 30. In the example, the door 30 is a door sliding in a direction (schematically indicated by the arrow X in figure 1) that is generally transverse or perpendicular to both sides 20a and 20b. However, this is not an essential feature since, according to possible other embodiments, the door 30 can be made to slide in a direction perpendicular or inclined with respect to said direction or arrow X, or it can be hinged to the body 20 so as to be able to perform angular displacements, for example in the form of a folding door (in which case the axis of rotation of the door may be substantially parallel to the sides 20a- 20b), or in the form of an angularly sliding door, i.e., slidable in a curved direction (in this case the axis of rotation of the door can be substantially parallel to the depth dimension of the body 20, indicated by the arrow Z in figure 1), all according to known technique.

Returning to the depicted non-limiting example, the door 30 can follow a substantially linear or at least partly arched path. For this purpose, a sliding zone A (figure 1) is identified on the front of the body 20, at which the door 30 is constrained so that it can slide. In this zone A a tray or receptacle is defined, designated by 40 in figures 3-4, suitable for the containment of washing agents, such as a washing agent in the form of a powder, or a washing agent in the form of a tablet or capsule, or a washing agent in fluid form (liquid or gel).

As can be seen in figures 3-4, the receptacle 40 is essentially obtained by a recess of the front of the dispenser 1, with a back wall 40a, two opposite first side walls 40b and 40c, and two opposite second side walls, only one of which being visible, designated by 40d. The receptacle 40 has a mouth generally opposite to the bottom 40a, i.e., an opening for loading and dispensing the washing agent.

In various preferential embodiments, within the receptacle 40 at least one spacer and/or positioning element is provided, configured for keeping a washing agent in solid form - typically a tablet or a capsule filled with a washing liquid or gel - in a position generally spaced apart with respect to at least one wall of the receptacle itself. At least one spacer or positioning element can be provided at the inner side of each of the walls that delimit receptacle 40, although the presence of at least one spacer element at a single wall may be sufficient (particularly the wall facing a sensor device, as will become clear later).

In the non-limiting example of figures 3-4, there is provided at least one spacer element 41 for the side wall 40b (at the right, with reference to figures 3-4) and at least one spacer and/or positioning element 42 for the back wall 40a (the depicted element 41 extends between the side wall 40b and the back wall 40a, while the depicted spacer and/or positioning elements 42 each extend between the side wall 40d and the back wall 40a).

As it cab ne imagined, in the event that a certain dose of a washing agent in powder or liquid is introduced into receptacle 40, the agent itself will fill a corresponding portion of the volume of the receptacle 40, coming into contact with the walls 40a-40d that delimit the receptacle; such a condition is schematically exemplified in figure 8, where in the receptacle 40 is a dose of a washing agent LD in liquid form (but it could be a washing agent in gel form or in powdery form). On the other hand, if a washing agent tablet or capsule ST is placed into the receptacle, as exemplified in figure 9, it will be spaced away from that wall or those walls that are provided with at least one spacer element 41. Note that in figures 8-9 the receptacle 40 is deliberately shown with the door 30 open, for greater clarity.

Still referring to the non-limiting example shown, the door 30 has a respective body, formed for example by moulding of thermoplastic material, which can be the same as the material constituting the body 20, for example a polypropylene filled with reinforcing material, such as talc or fiberglass. The door 30 is slidable in a guided manner on the body 20 in the sliding zone A, so that it can move between a closed position and an open position of the receptacle 40, as shown in figures 1 and 3-4, respectively. For this purpose, a guide or constraint arrangement is operationally set between the body 20 and the door body 30, which in the example includes sliding guides, not indicated, obtained according to a technique known in itself.

Referring to figures 1 and 3-4, in the example shown, next to the zone A of the body 20 a cover 2 is associated, equipped with a corresponding coupling/releasing device 2a that is manually operable. The cover 2 is preferably hinged to the dispenser body 20 to rotate according to a generally horizontal axis, but it can be mounted slidable. The cover 2 is intended to cover a corresponding area of the front of the dispenser 1 where the inlet of a non-visible tank of a second washing agent, in particular a liquid washing additive, such as rinse aid, is located. In the same area subtended by the cover lid 2 there may also be an outlet opening forming part of a liquid additive dispensing system, and for this purpose the body of the cover 2 preferably has openings or passages to allow the flow of this liquid additive into the washing tank of the machine, not represented herein. As mentioned, in this exemplificative description, it is assumed that the dispenser 1 is fixed to a wall delimiting the cited tank (particularly a wall defined by the dishwasher door), so that in the closed-door condition the upper side 20a of the peripheral profile of the body 20 extends higher than the lower side 20b: In this way, during the operation of the machine, the body 20 is oriented substantially vertically, favouring the outflow of washing agents towards the inside of the tank. The presence of the aforementioned liquid additive dispensing system and its tank and cover 2 is not necessarily linked to the implementation of the present invention, such that these components could also be omitted.

The door 30 is preferably urged towards the respective condition of opening of the receptacle 40 by means of elastic means, not visible, comprising, for example, a spring bound between the body 20 and the door 30, according to a technique in itself known (see for reference, for example, US5884821 A, whose teachings in this regard are considered incorporated herein). Preferably, between the body 20 and the door 30 also a locking/ releasing system of the door is operative, which can be controlled by a dishwasher programmer, not represented, or manually. In various embodiments this system comprises a coupling member 3a arranged in the zone A, as visible for example in figure 1. The coupling member 3 a is intended to cooperate with a (non-visible) retaining element provided on the door 30, and may, for example, include or have associated a rotating shaft 3a' (figure 2), which passes through the dispenser body 20 and can be operated by an actuator system 4 (figure 2) arranged on the back of the body 20.

In various embodiments, the locking/releasing system of the door 30 also comprises a button, designated by 3b in figure 1, which is carried by door 30 and is manually operable by a user, according to a technique known in itself; The button 3b can be operatively associated with a manual release mechanism, also carried by the door 30 and including the aforementioned retaining element. The presence of the button 3b and the associated mechanism 3c is merely optional, as the function of manual switching of the coupling/releasing system can be obtained directly from the member 3 a, for example by equipping such a member with a manually operable lever to rotate it, and wherein this lever - exemplified in figure 1 - protrudes at least in part beyond the door 30 when it is in the closed position, in order to be accessible to the user (see for reference the aforementioned US5884821 A, whose teachings in this regard are considered incorporated herein).

The dispenser 1 subject of the invention is equipped with a sensor device of a capacitive type, configured to detect the presence and / or the type of a washing agent present in receptacle 40. This sensor device, in a possible embodiment thereof, is shown schematically in figure 2, where it is designated as a whole by 50. In the case exemplified, the sensor device 50 is mounted inside a cavity defined in the dispenser body 20, in a position generally adjacent to an external surface of the receptacle 40, in particular the external surface of the side wall designated by 40b in figure 3.

The rear part of the dispenser body 20 may be shaped so as to obtain at least part of the aforementioned tank for the aforementioned second washing agent (not visible in the figures), which does not extend into the area where the receptacle 40 is defined. By the way, in different embodiments, the rear part of the dispenser body 20 could be shaped so as to create such a tank which also extends in the area of the receptacle 40, for example with a wall of the rear part that is set between the sensor device 50 and the corresponding flanked wall of the receptacle 40.

The sensor device 50 has at least one sensitive part which is configured for the detection of electrical capacity. In accordance with one aspect of the invention, the at least one sensitive part comprises at least one single detection electrode, placed outside the receptacle 40, in a contiguous or side by side position with respect to a wall of the plurality of walls that delimit the receptacle, and a control circuit of the sensor device - to which the at least one single detection electrode is connected in signal communication - is configured to detect the presence and/or the type of a washing agent present in the receptacle as a function of a first value representative of electrical capacity between the at least one single detection electrode and the washing agent present in the receptacle.

In other words, the sensor device uses a configuration in which a single detection electrode, such as a single measuring electrode, does not require a corresponding second opposed electrode, as in the case of the prior art, since the same washing agent obtains a sort of "virtual" electrode. Therefore, even in the case of a plurality of single measuring electrodes, each single measuring electrode does not require a respective opposed second electrode.

In the event that the sensor device 50 provides a compensation function, the device itself can also include at least one single reference electrode, which does not require a corresponding second opposed electrode. Also in this case the presence of a plurality of single reference electrodes could be foreseen, where each single reference electrode does not require a respective second opposed electrode.

Also referring to figure 5, in the non-limiting example shown the sensor device 50 comprises a single detection electrode Jd and a single reference electrode Jr, both arranged outside the receptacle 40.

The single detection electrode Jd is placed in a contiguous or side by side position with respect to one of the walls that delimit the receptacle 40, while the reference electrode Jr is instead in a non-contiguous position or not set side by side with respect to any of the walls that delimit the receptacle 40.

As mentioned, in the example shown, the electrode Jd is contiguous or set side by side with respect to the side wall 40b (figure 3) of the receptacle 40, but in other embodiments the sensor device 50 could be mounted in such a way that the electrode Jd is contiguous or set side by side with respect to any of the other walls that delimit the receptacle 40.

Preferably, the electrode Jd has an area and an operative position such as to affect with its electric field only a lower area of receptacle 40, or an area that is in any case occupied by the washing agent (if this is actually present). This is provided in order to prevent the electrode Jd from also performing measurements at the upper area of the receptacle, which could be free of washing agent, and in this case distort the measurement (think, as usually happens, to a dose of concentrated washing agent that does not correspond to the entire volume of the receptacle, but only to a fraction thereof). However, in other embodiments, the at least one detection electrode Jd could also affect other portions of the receptacle 40, and be configured, for example, to carry out detections both in the lower and upper areas of the receptacle. It is not excluded from the scope of the invention the case of a sensor device that involves the use of several sensitive parts, each comprising a respective single detection electrode Jd in a position next to one and the same wall of receptacle 40, where each single detection electrode operates according to the logic described here (and therefore with each single detection electrode that is able to perform its own detections independently from those of the other detection electrode or electrodes being provided).

In preferential embodiments, the sensor device 50 comprises at least one electrically insulating substrate, which obtains a preferably flat and relatively thin circuit support, such as a printed circuit board. This support can be formed with a material suitable for obtaining printed circuits, such as FR4 or a similar composite material such as fiberglass, or even in ceramic or polymer-based material, preferably a mouldable material.

In the depicted preferential example a single support is provided, designated by 51, which bears on it both the electrodes Jd and Jr. On the support 51, for example in a region intermediate to the two electrodes Jd and Jr, additional components can also be associated, such as a control circuit MC of the device, in particular implemented by an electronic controller, as well as related electrical conductor elements and terminals for the external electrical connection of the sensor device 50. The circuit or controller MC can be for example a microcontroller or an ASIC chip. The circuit or controller MC preferably comprises at least one processing and/or control logic unit, one memory circuit and inputs and outputs, including analogue/digital inputs. figure 6 shows a possible embodiment of the sensor device 50. As noted, the electrodes Jd and Jr are connected to respective inputs of the circuit or controller MC, via conductors in the form of electrically conductive tracks Ld and Lr present on the support 51.

Additional tracks may be connected to additional inputs and outputs of the circuit or controller MC, such as two tracks for power supply and at least one track for output of a signal (represented but not indicated by reference numbers), with these tracks defining at the distal end respective terminals Tl, for the external connection of the device 50.

The electrodes Jd and Jr are formed of electrically conductive material, such as a metal material or a metal alloy, and are associated with the front or the back of the support 51. The electrodes Jd and Jr can be, for example, in the form of plates or foils applied or engraved on the support 51, or consist of an electrically conductive layer - similar to the tracks Ld and Lr - deposited on the support 51, for example via screen printing or a similar technique.

A compensation arrangement equipping sensor device 50 may comprise at least one temperature sensor, for the functions explained below. In the case exemplified in figure 6, a temperature sensor is indicated with TS and is provided on the support 51, also connected to corresponding conductive tracks that have at the distal end respective connection terminals T2. The temperature sensor TS, when provided, can be for example an NTC thermistor. Alternatively, the temperature sensor TS could be connected to the circuit or controller MC, as exemplified in figure 7.

The terminals T 1 and/or T2 are preferably generally flat, for example made by suitable shaping of conductive tracks of the printed circuit board (PCB) that constitutes the support 51 ; alternatively, additional electrical connection elements could be welded on the terminals Tl and/or T2. The terminals Tl and/or T2 (and/or any additional electrical connection elements) are preferably arranged to obtain respective electrical connectors, particularly for connecting the sensor device 50 to other electrical parts of the dispenser 1 and/or to a dishwasher control unit.

In other embodiments, the circuit or controller MC is not provided on the at least one support 51 of the sensor device, and the control circuit of the device itself is either remotely located, within the dispenser 1, or implemented in the dishwasher control system. For such cases, therefore, on the support 51, only the electrode Jd will be provided, and possibly the electrode Jr and/or the temperature sensor TS, with corresponding conductive tracks and terminals and/or connectors, for the electrical connection to the electronic circuit in a remote position.

The sensor 50 is preferably interfaced to an external control system, such as a dishwasher control board, for example through the connector obtained by the terminals T1 (and possibly the connector obtained by the terminals T2). For this purpose, the circuit or controller MC is designed for data transmission, preferably via a pulse-width modulated signal (PWM); however, other transmission systems may be adopted, for example in a serial format, such as an interface and/or a single edge nibble transmission (SENT) protocol. The signals sent by the circuit or controller MC may comprise information representative of the presence and/or the type of washing agent, for example a liquid or powder washing agent or a tablet or capsule, and/or information representative of the presence of an abnormal operating condition, for example for the purpose of warning and/or status signalling (e.g., absence of detergent in the receptacle 40 following the start of a washing cycle involving the use of detergent, and/or presence in the receptacle 40 of a detergent other than that for which a selected washing cycle is specifically designed, and/or an abnormal presence of detergent in receptacle 40 even after the washing cycle, as a solidified powder detergent due to moisture).

In various embodiments, an auxiliary control electrode may be provided, with such an auxiliary control electrode which is substantially adjacent to or at least partially surrounds a single detection electrode. In the case of figure 6, such an auxiliary electrode is designated by Jn, and the detection electrode Jd is within a region of the support 51 that is substantially circumscribed by the electrode Jn.

The auxiliary control electrode Jn is also connected, via a respective conductive track Ln, to a terminal of the circuit or controller MC. The same electrode Jn can be obtained from a track of electrically conductive material, which preferably almost completely surrounds the electrode Jd, for example obtained in a way similar to the tracks, Ld and Lr, possibly with dimensions greater than the width of the tracks Ld, Lr.

The sensor device 50 of figure 7 is of a design similar to that of the device of figure 6, with the difference that the detection electrode Jd has a more extended area, and therefore also the auxiliary control electrode Jn, when present, is correspondingly larger. In addition, in the case of figure 7, the temperature sensor TS is connected directly to the circuit or controller MC via respective conductive tracks.

In various embodiments, in one and the same circuit support 51 there can be identified a first portion 51a, designed to be at least partly substantially next to a wall of the receptacle 40 (here the wall 40b), and a second portion 5 lb designed not to be facing any of the walls of the receptacle 40, as can be seen, for example, also in figure 5. The first portion 51a of the support 51 has at least one detection electrode Jd associated thereto, while the second portion 51b has at least one reference electrode JR associated thereto, when the reference electrode is provided.

In the depicted example a single circuit support 51 is provided, in which the parts 51a and 51b are defined, and to which both the electrodes Jd and Jr are associated, and further comprising the circuit or controller MC. However, in less advantageous possible variant embodiments, there may be provided several separate circuit supports, connected to each other by suitable electrical interconnection means and, possibly, mechanical interconnection means, for example at least one circuit support corresponding to the portion 51a and at least one circuit support corresponding to the portion 51b, with conductors and/or electrical connectors to connect the electrically conductive tracks of a support to the electrically conductive tracks of the other support. A circuit support may also be provided for the circuit or controller MC, or the latter may be placed on a circuit support bearing at least one of the electrodes Jd or Jr.

In the example shown the electrodes Jd and Jr are on one and the same major face of the support 51, which is opposite to the major face of the support 51 facing the receptacle 40, but this is not an essential feature. In other embodiments, in fact, the electrodes Jd and Jr can be on the major face of the support 51 which is directly facing a wall of the receptacle 40. For these embodiments it may also be advantageous that certain larger components of the device 50, such as the circuit or controller MC and/or the temperature sensor TS, if any, are located on the major face of the support 51 opposite that on which the electrodes Jd and Jr are located (in these embodiments, the electrical connection elements for connecting the electrodes to the circuit or controller MC may for example include metallized through holes of the support 51): in this way, at least the detection electrode Jd can be closer to the relevant wall of the receptacle 40 and directly facing it. It is also possible to provide the electrode Jd and the electrode Jr on two different major faces of the support 51, respectively.

As it can be seen from figure 5, the detection electrode Jd is in a position substantially alongside with respect to a respective wall of the receptacle 40, herein the wall 40b. As mentioned, the electrode Jd can be directly facing this wall, or between this wall and the electrode Jd there can be found a corresponding portion of the support 51 made of electrically insulating material and/or other parts made of electrically insulating material of the body of the dispenser 20. In any case, the electrode Jd is located in a position relatively close to the aforementioned wall of the receptacle.

On the other hand, when provided, the reference electrode Jr is in a position spaced apart with respect to the walls that delimit the receptacle 40, that is, it is not located adjacent or alongside to any of said walls, and therefore it is in a position more distant than the washing agent that can be contained into the receptacle 40. This is because, as will be seen, the electrode Jr is used, for example, to provide a reference value used - basically for compensation purposes - during the detection of the presence and/or the type of washing agent performed via the electrode Jd.

As it ca be seen, the sensor 50 includes capacitive elements that each include a single electrode Jd or Jr. As mentioned, the term "single" here means that each electrode Jd or Jr belongs to a capacitive element that does not necessarily have to have a respective generally facing additional electrode, as in a flat capacitor of the type provided for in FR 2940037 A. In other words, in the solution proposed herein, the detection electrode Jd obtains the sensitive armature of a sort of "virtual capacitor", whose other armature is obtained by the medium subject to detection present in the receptacle 40, and wherein at least the interposed wall (40b) of the receptacle 40 (and any possible further parts of the body 20) constitutes at least part of the dielectric or insulator between the armatures of that virtual capacitor, to which there may be added the dielectric or insulator consisting of the circuit support 51 (if the electrode Jd is not directly facing the said wall, as in the case of figure 5) or air, as explained below.

In practice, the electrode Jd obtains, together with the corresponding control electronics, a capacitive sensor with at least one single electrode, able to detect the presence or the absence of a washing agent inside the receptacle 40, even without direct contact with it.

As it will be seen, moreover, the sensor device 50 that equips the dispenser according to the invention is advantageously able to detect the type of washing agent, preferably discriminating at least between a liquid washing agent, a powder washing agent, a tablet or a capsule comprising a washing agent.

Such an operation is based on the principle of detection of the electrical capacity of a capacitor: the electrode Jd is the sensitive side of the capacitor and constitutes its armature, while the possible presence in the vicinity of an electrically conducting medium (such as a washing agent) obtains the other armature of the capacitor. In this way, presence or absence of an electrically conductive medium near the electrode Jd determines an electrical capacity that the control electronics MC is able to detect and measure.

In the application considered herein, the electrode Jd is therefore likely to obtain at least two different capacitive structures depending on the presence or absence of a washing agent in receptacle 40, and precisely at least:

- a first capacitive structure having a first value representative of electrical capacity, when the electrode Jd is at least partially flanked by a washing agent, inside receptacle 40, wherein this value is generally proportional to the type of washing agent and/or the distance of the washing agent from the electrode Jd, and

- a second capacitive structure having a second value representative of electrical capacity, when the electrode Jd is not flanked by a washing agent inside the receptacle 40.

The circuit or controller MC is substantially designed to discriminate the value representative of electrical capacity associated with the electrode Jd at least between the aforementioned first and second values representative of electrical capacity and consequently identify at least the presence or absence of the washing agent in the receptacle 40.

The circuit MC is preferably a digital electronic microcontroller equipped with an analog-to-digital converter. Note, however, that the functions of the circuit MC can be at least partially implemented via dedicated external circuits: for example, in a preferred embodiment, the circuit MC consists of a microcontroller that implements an analog-to-digital converter module, but in other implementations the controller MC may include a microcontroller (or a microprocessor or an ASIC or FPGA integrated circuit) and an integrated circuit (or external or independent) dedicated to fulfilling the analog-to-digital converter functions.

Microcontrollers suitable for the application described herein are commercially available.

Figures 6-7 show in schematic form a circuit or controller MC which, by way of example only, includes at least two signal inputs, to which the electrodes Jd and Jr are connected in a single configuration (i.e., not connected in common or in parallel to other electrodes), via corresponding conductive tracks Ld and Lr.

In a preferred embodiment, the detection of a value representative of electrical capacity at the aforementioned inputs of the circuit or controller MC (hereinafter referred to as INd and INr) is carried out indirectly, based on the measurement of a voltage. In such a case, preferably, the inputs of the MC controller are analog inputs and the controller itself implements or has associated an analog- to-digital converter. figure 10 exemplifies in a partial and schematic way a possible control circuit of the sensor device 50, associated with the respective wall 40b of the receptacle 40. In the example, each input of interest of the circuit or controller MC - here the inputs designated by INd and INr - is associated with a sampling circuit, or Sample and Hold, which includes a controllable switch SS and a capacitor CHOLD, herein also identified a sampling switch and sampling capacitor. The controllable switch SS is switchable between a first position, where the sampling capacitor CHOLD is connected to a voltage source VDD, and a second position, where the same capacitor is connected to a respective electrode Jd or Jr. Preferably the voltage is a DC voltage, for example the supply voltage of the circuit or controller MC (e.g., 5 V). The circuit or controller MC has means for causing the controllable switch to switch from the first position to the second position, so as to discharge the sampling capacitor CHOLD proportionally to the value of capacitance associated with the corresponding electrode its Jd or Jr. Moreover, the circuit or controller MC has means to determine the voltage at the input INd or INr when the controllable switch SS is in its second position, this voltage being indicative of the electrical capacity associated with the electrode Jd or Jr. The circuit or controller MC then has comparator means, for comparing a value representative of the voltage determined at least at the input INd with at least one relative reference threshold, or at least two reference thresholds, and thereby deduce whether the electrode Jd is flanked or not flanked by a washing agent contained into to receptacle 40.

In the example of figure 10, sampling of the inputs INd and INr is carried out using respective Sample and Hold circuits associated with corresponding analog-to-digital converters ADC. With the switch SS in its second position, a charge balance is substantially determined between the capacitance of the capacitor CHOLD and the capacitance associated with the electrode Jd or Jr; in other words, with this charge balance the capacitor CHOLD discharges proportionally to the capacitance of the "virtual capacitor" defined by the electrode Jd. By means of the converter ADC the amount of charge, i.e., a residual voltage of the capacitor CHOLD, is therefore determines, which is then compared with a predefined reference threshold, in order to deduce whether the electrode Jd is facing the washing agent or is not facing the washing agent, or whether the electrode Jd has assumed the first capacitive structure or configuration or the second capacitive structure or configuration indicated above.

Following the aforementioned balance between the charges of the capacitor CHOLD and the electrode Jd, the value representative of voltage at the ends of the capacitor and/or at the input INd may substantially coincide or be greater or lower than a certain reference threshold, stored in the controller MC. For example, in an embodiment, the controller MC can be programmed so that the detection at the input INd of a value representative of a voltage equal to or above the predefined threshold is indicative of the fact that a washing agent contained in receptacle 40 is aligned to the electrode Jd, whereas the detection at input INd of a value representative of a voltage below the threshold may be indicative of the fact that no washing agent is aligned to the electrode Jd. In figure 10, the dotted block designated by VE is intended to schematically represent the functionality of the "virtual" electrode or armature obtained by the washing agent, as explained above, and with FL are schematically designated the electric field lines related to the detection electrode Jd.

It will be appreciated that the functionality described with reference to figure 10 can be also obtained with circuits being different but technically equivalent to the one exemplified.

In the example shown in figure 11 the analog inputs INd and INr of the circuit or controller MC are connected to a multiplexer MTP, which substantially operates as an electronic switch, having a single sampling or Sample and Hold circuit associated thereto, including a sampling capacitor CHOLD and a sampling switch SS. Also in this case the switch SS is switchable between a first position, connecting to the voltage VDD and a second position, for connection to an output of the multiplexer MTP, that is, a position of connection to the electrodes Jd and Jr.

Via the multiplexer MTP the inputs INd and INr, and therefore the electrodes Jd and Jr, are connected sequentially or alternately to the switch SS. The switch SS is switched cyclically, in a synchronized way with respect to the operation of the multiplexer MTP, between the first position, of charge of the capacitor CHOLD, and the second position, of connection of the same capacitor to the input INd or INr selected at the time by the multiplexer MTP, and then to the corresponding electrode Jd or Jr. As explained above, when the washing agent is in front of the electrode Jd, the electrode Jd has a first value representative of electrical capacity associated thereto, while otherwise it has a second value representative of electrical capacitance associated thereto.

The operating principle described is to some extent dependent on environmental or common-mode stresses (temperature, humidity, aging, electronic noise, etc.). For this reason, in various preferential embodiments, the controller MC is programmed for carrying out a measurement taking into account a reference or compensation value, for example by carrying out a differential-type measurement, using at least one reference electrode Jr for this purpose.

Since environmental stresses are represented by an offset on the measurement of the voltage value determined at an input of the controller MC, by performing a correlation and/or a differential measurement between the representative values obtained by at least one detection electrode Jd and at least one reference electrode Jr it is possible to derive both the measurement on the detection electrode Jd, and to subtract the common-mode effect present thereon, and therefore cancel any drift produced by environmental conditions, including the aging of the system.

For this purpose, as seen above, the sensor device 50 can include at least a single detection electrode Jd in a position next to a wall of the receptacle 40, such that the corresponding electric field FL can be affected by the washing agent possibly present in the same receptacle. Preferably, the sensor device also includes at least one reference electrode Jr, which is placed relatively close to the single detection electrode Jd - so as to be affected by the same environmental or commonmode conditions (such as temperature, humidity, aging, electronic noise, etc.) - but where this position is relatively distant from the receptacle 40, so that its electric field cannot be affected by the washing agent that may be present in the receptacle.

The electrodes Jd and Jr therefore do not realize the two armatures of one and the same capacitor.

The two electrodes Jd and Jr can have the same measuring area, in order to have the same type of response to the aforementioned environmental or commonmode stresses. As mentioned, the electrodes Jd and Jr can lie substantially according to one and the same plane, as in the examples shown.

Thanks to this configuration, for example, it is possible to apply a differential measurement between the two electrodes Jd and Jr, in order to automatically compensate for all environmental or common-mode effects that may affect the detection made through the electrode Jd.

The circuit or controller MC therefore includes measurement means designed to calculate the difference between the representative voltage value relating to the input INd and the representative voltage value detected at the input INr, with its comparator means designed to compare the consequent differential value with one or more reference thresholds (as mentioned, the mentioned voltage values are in turn representative of values of electrical capacity).

The value representative of voltage acquired by the input INd can be used to determine the type of washing agent. For this purpose, the controller MC is preferably programmed so that the measurement relating to the input INd, preferably compensated as indicated above, is compared with a plurality of predefined thresholds or values, or compared with values corresponding to possible different washing agents.

Once the measurement has been stabilized with respect to the environmental components (compensated or differential measurement via the electrode Jr), the controller MC proceeds to the processing for the determination of the type of washing agent inside the receptacle 40. As mentioned, this is preferably done through the method of comparing with at least one corresponding threshold. In the receptacle there can be substantially present:

- a liquid detergent ST, as exemplified in figures 10-11;

- a washing powder PD, as exemplified in figure 12,

-a detergent in compacted tablet ST or in form of a capsule (pod or tab) LT, as exemplified in figures 13 and 14, respectively,

- air (absence of detergent).

Taking advantage of the different equivalent permittivity given by the type of detergent and positioning thereof inside the receptacle 40, a different response is obtained from the detection electrode Jd, and it is therefore possible to discriminate between the different types.

Also the positioning of the detergent, in fact, helps to diversify the measures, since - as explained in relation to figures 8-9 - a fluid detergent LD and a powder detergent PD will conform to the geometry of the receptacle 40, while a detergent in the form of a tablet ST or LT tablet will maintain its own geometry, and therefore will not conform to the internal profile of the receptacle, maintaining the presence of air between the measuring electrode and the detergent, wherein such a presence of air also acts as a dielectric, further lowering the measurement value.

For this purpose, in particularly advantageous versions, inside the receptacle 40, suitable spacer means can be provided, such as those previously exemplified with 41, in order to keep the detergent tablet ST or LT at a certain distance with respect to the wall of the receptacle (here the wall 40b) to which the sensor device 50 is associated, and thus further increase the measurement difference between tablet and washing powder or liquid. It will be appreciated that, thanks to the presence of the aforementioned spacer means, even in the case in which a detergent tablet is formed by compacting the same material as a washing powder, it is possible to discriminate between them the two versions of detergent (the detergent in tablet will be detected with a decidedly lower signal than the detergent powder, due to the greater distance between the washing agent and the sensor device 50, i.e., the presence of the greater dielectric represented by the air between the tablet and the inner side of the wall 40b).

The representative value read via the detection electrode Jd is digitalized by the controller MC and assumes the value of pure number following the quantization process; said signal is referred to here as "Raw Data". Each type of detergent, therefore, will give a different value of Raw Data read by the circuit or controller MC.

An example is provided below for the three types of detergent exemplified. Let’s assume that the geometry of the electrode Jd is optimized to provide a maximum measurement at the minimum level of liquid detergent normally recommended for washing (typically 25 ml), or at a lower area of the interposed wall 40b.

Liquid detergent LD: being liquid, this type of detergent has a high dielectric constant and will fill a corresponding portion of the volume of the receptacle 40, that is, with the absence of air between the detergent and the wall 40b: this allows to have a very high measurement value, for example a Raw Data equal to 10,000.

Powder detergent PD: being in powder, this detergent has a medium dielectric constant, in any case lower than that of the liquid detergent LD, and will fill a corresponding portion of the volume of the receptacle 40, with a substantial absence of air between the detergent and the wall 40b: this allows to have a medium measurement value, for example, a Raw Data of 4,000.

Detergent in tablet ST or LT : being in tablet form, this detergent has a low dielectric constant and will not completely fill a corresponding portion of the volume of the receptacle 40, with the presence of air between the detergent itself and the wall 40b (as mentioned, this effect can be ensured through the presence of the aforementioned spacer means 41): this results in a low measured value, such as a Raw Data of 1,000.

By contrast, in the absence of any detergent, the receptacle will contain air, with a reference Raw Date, for example equal to 0.

Once the nominal values for each type of detergent have been defined in this way, the corresponding thresholds are stored in the controller MC, in order to obtain a univocal response and consequently enable the identification of the type of detergent currently present inside the receptacle 40. So, for example, if following a detection made through the electrode Jr a Raw Data between 9,000 and 11,000 is obtained, it can be deduced that the detergent is in liquid form; if the Raw Data is instead between 3,000 and 5,000, for example, it can be deduced that the detergent is in powdery form; if the Raw Data is instead between 10 and 2,000, for example, it can be deduced that the detergent is in tablet form.

In practice, the measurement cycle within the controller MC can perform the following comparisons:

- if the numerical value of Raw Data is lower than a first threshold value (for example equal to 10), then the "air" state is assigned, or absence of detergent;

- if the numerical value of Raw Data is between the first threshold value and a second threshold value (for example equal to 2,000), then the status "tablet detergent" is assigned;

- if the numerical value of Raw Data is between the second threshold value and a third threshold value (for example equal to 5,000), then the status "washing powder" is assigned;

- if the numeric value of Raw Data is higher than the third threshold value, then the status "liquid detergent" is assigned.

To improve the measurement, it is possible to provide an auxiliary control electrode Jn, preferably placed at least partially near and/or around the electrode Jd, as previously exemplified in figures 6-7. The electrode Jn is closer to the electrode Jd than the electrode Jr.

Figures 15 and 16 exemplify a possible mode of operation of the abovementioned auxiliary control electrode Jn, or at least one phase of the operation of the device 50 involving the use of such an electrode Jn; further modes of operation or further phases of such operation may include at least one of:

- a connection of the auxiliary control electrode Jn to a positive potential;

- a capacitance measurement using the auxiliary control electrode Jn;

- a capacitance measurement of the auxiliary control electrode Jn at the same time or in parallel with the measurement by means of the measuring electrode Jd.

Figure 15 schematically exemplifies the case of a receptacle 40 whereinto, for example at the end of a previous wash, a few drops of water WD remained, which could affect the detection during the next washing cycle, if not dried (a capacitive electrode is inherently sensitive to water, due to the high permittivity of the latter).

In the example, the electrode Jn can be connected to a low electric potential (for example to ground) via a respective terminal of the controller MC, to which a corresponding driving circuit Dr is connected.

In case of a measurement in the absence of the auxiliary control electrode Jn, or else with such an electrode Jn being undriven (as shown in figure 15), the field lines FL relating to the detection electrode Jd would be uncontrolled, being able to be affected by the droplets WD, thus potentially distorting the measurement.

By contrast, in the presence of the auxiliary control electrode Jn suitably controlled by the controller MC, for example connected to ground in at least one phase of the measurement that is carried out by means of the measuring electrode Jd (for example as schematized in figure 16), the distribution of the electric field lines FL relating to the detection electrode Jd is improved, which lines are for example forced to close around the same electrode Jd, that is, on the auxiliary control electrode Jn, as shown in figure 16. In other words, through an appropriate control of the electrode Jn, it becomes possible to optimize the detection area, for example by limiting it to that of actual interest, eliminating or reducing detection errors due to the possible presence of water residues WD that remain into receptacle 40 after a washing cycle.

In various embodiments the electrode Jn can be driven by the circuit Dr with a predefined voltage defined by firmware. For example:

- if the circuit Dr drives the electrode Jd with 0 V (ground), the strength of the electric field is reduced to a minimum, as exemplified in figure 16, so that the field lines LF are oriented in such a way that their path is as short as possible;

- if instead the circuit Dr drives the electrode Jd with a maximum available voltage (for example equal to the power supply of the controller MC, which is herein assumed to be 5 V), the strength of the electric field is maximized, so that the field lines FL are oriented in such a way that their path is as long as possible, but always closing between the electrodes Jd and Jn.

In this example, therefore, the auxiliary control electrode Jn driven in voltage does not perform a measurement, but constitutes an element to force the electric field lines FL to close with variable intensity. It will therefore be appreciated that this auxiliary electrode Jn does not replace the virtual armature obtained by the washing agent, but can be meant as an auxiliary part, which may be connected to the detection electrode Jd to change the shape and measurement properties thereof.

The presence of the auxiliary control electrode Jn allows, via software, to manage the dynamics by maximizing the signal of the detection electrode Jd, so that the field lines FL pass through the substances to be measured only, near the same electrode Jd . As can be seen in the example of figure 16, the presence of the auxiliary control electrode Jn guides the field lines FL and orients them so that their path is as short as possible, but that they pass through the medium of interest to be measured (i.e., the detergent). This increases the efficiency of the measurement by optimizing the percentage of field lines that actually pass inside the medium of interest, compared to the percentage that passes through the material of no interest for the measurement.

As mentioned, the principle of operation of the sensor device 50 is to some extent dependent on the ambient temperature, when considered in an absolute way. Since the temperature effect is represented by an offset on the measurement relating to the electrode Jd, and if the detection quality is to be further improved, any thermal drift produced by possible temperature changes can also be compensated by means of a temperature sensor, for example of the type indicated with TS in figures 6 and 7, according to a technique known per se. From the given description, the characteristics of the present invention are clear, as well as its advantages.

The described dispenser, with the corresponding sensor device, has a simple, economical and compact structure, which is reliable, even in the long term, and allows to accurately identify the presence or absence of a washing agent, as well as its type.

It is clear that numerous variations are possible for the person skilled in the art to the dispenser described as an example, without departing from the scope of the invention as defined by the claims that follow.

The electronic circuit of the sensor 50 is preferably subject to an initial calibration or configuration, based on the type and/or conductivity of the washing agents subject to detection, in particular considering that in the case of less conductive, or resistive, washing agents, there could occur a sort of electrical resistance virtually connected in series to the measuring capacitor, which resistance could lead to an increase in the time required to reach the final threshold value (an increase in the charging time of the "virtual capacitor" to which the electrode Jd belongs and/or an increase in the discharge time of the capacitor CHOLD); with this in mind, the initial configuration can be envisaged, for example, to take into account of possible delays in the sampling measurement, and to avoid incorrect measurements based on values that have not yet been well stabilised.

The electronics of the sensor device 50 can be initialized and/or calibrated during production, with storage of the corresponding software or program and/or of at least some of the variables (such as one or more thresholds used in the detection of the presence and/or the type of washing agent). The calibration phase may include a reading of the electrode Jr, for example to define a cancellation of the initial offset, or to compensate for parasitic capacities due to materials, structures, thicknesses, etc. of the sensor and/or its installation system.

In order to increase the detection accuracy and/or dynamics, the sensor device 50 can be possibly equipped with multiple sensitive parts, each of which including a single detection electrode Jd, and/or more than one reference electrode Jr.

Claims

1. A washing agent dispenser for dishwashers, comprising a dispenser body (20) and a door (30), wherein the dispenser body (20) has a front at which a receptacle (40) for the containment of washing agents (ST, LT, LD, PD) is defined, which is delimited by a plurality of walls (40a-40d), wherein the door (30) is mounted movable on the dispenser body (20) to be displaceable between a closing position and an opening position of the receptacle (40), wherein the dispenser (1) comprises a sensor device (50) having at least one sensitive part which is configured for detecting electrical capacity, wherein the at least one sensitive part comprises at least one single detection electrode (Jd), arranged outside the receptacle (40) in a contiguous or side by side position with respect to a first wall (40b) of the plurality of walls (40b-40d) delimiting the receptacle (40), and wherein the sensor device (50) comprises a control circuit (MC) to which the single detection electrode (Jd) is connected in signal communication, the control circuit (MC) being configured for detecting presence and/or type of a washing agent possibly present in the receptacle (40) according to a first value representative of electrical capacity between the single detection electrode (Jd) and the washing agent possibly present in the receptacle (40).

2. The dispenser according to Claim 1, wherein the sensor device (50) comprises at least one compensation arrangement (Jr; TS), for compensation of the first value representative of electrical capacity.

3. The dispenser according to Claim 2, wherein the compensation arrangement (Jr; TS) comprises at least one reference electrode (Jr) arranged in a position which is not contiguous or side by side with respect to the walls of the plurality of walls (40a-40d) delimiting the receptacle (40), and connected in signal communication to the control circuit (MC).

4. The dispenser according to Claim 3, wherein the control circuit (MC) is configured for compensating the first value representative of electrical capacity as a function of at least one further value representative of electrical capacity acquired via the at least one reference electrode (Jr), the control circuit (MC) being in particular configured to perform a correlation and/or a differential measure between the first value representative of electrical capacity and the further value representative of electrical capacity.

5. The dispenser according to any one of Claims 2-4, wherein the compensation arrangement (Jr; TS) comprises a temperature detector (TS).

6. The dispenser according to any one of Claims 1-5, wherein the control circuit (MC) is configured to compare the first value representative of electrical capacity, or a first compensated value representative of electrical capacity, with at least one corresponding reference threshold, to deduce presence and/or type of a washing agent possibly contained in the receptacle (40), where preferably: the control circuit (MC) is configured to compare the first value representative of electrical capacity, or the first compensated value representative of electrical capacity, with a plurality of reference thresholds, to deduce the type of washing agent possibly contained in the receptacle (40) between a liquid washing agent (LD), a powder washing agent (PD), a washing agent in tablet or capsule form (ST, LT).

7. The dispenser according to any one of Claims 1-6, wherein, at an inner side of the first wall (40b), at least one spacing element (41) is provided, suitable for keeping a washing agent in the form of a tablet (ST, LT) in a position spaced apart from said inner side of the first wall (40b).

8. The dispenser according to Claim 1, wherein the single detection electrode (Jd) and the control circuit (MC) are on one and the same circuit support (51) mounted on the dispenser body (20), where preferably on said one and the same circuit support (51) there is also mounted at least one compensation arrangement (Jr; TS), for the compensation of the first value representative of electrical capacity.

9. The dispenser according to Claim 1 or else Claim 3, wherein:

- the control circuit (MC) has at least one signal input (INd, INr) to which the single detection electrode (Jd) or else the at least one reference electrode (Jr) is connected, respectively, the at least one signal input (INd, INr) being also connected or connectable to a circuit including a controllable switch (SS) and a capacitor (CHOLD), the controllable switch (SS) being switchable between a first position, in which the capacitor (CHOLD) is connected to a voltage source (VDD), and a second position, in which the capacitor (CHOLD) is connected to the at least one signal input (INd, INr), and

- the control circuit (MC) is configured to switch the controllable switch (SS) from the first position to the second position, to cause a discharge of the capacitor (CHOLD) in a way proportional to the first value representative of electrical capacity, or else the further value representative of electrical capacity, respectively, associated with the at least one signal input (INd, INr).

10. The dispenser according to any one of Claims 1-9, wherein the single detection electrode (Jd) has an area such as to affect only a lower or intermediate portion of the receptacle (40).

11. The dispenser according to any one of Claims 1-10, wherein the sensor device (50) also comprises an auxiliary control electrode (Jn) in a position close to the single detection electrode (Jd) and which is controllable by the control circuit (MC) in order to improve a detection operated through the single detection electrode (Jd), preferably in order to avoid or reduce abnormal measures resulting from possible presence of water residues in the receptacle (40).

12. A dishwasher, comprising a washing agent dispenser according to one or more of Claims 1-11.

13. A method for detecting presence and/or type of a washing agent in a receptacle (40) of a washing agent dispenser (1) for dishwashers, comprising the steps of:

- providing at least one single detection electrode (Jd) outside the receptacle (40), in a contiguous or side by side position with respect to a wall (40b) of a plurality of walls (40b-40d) delimiting the receptacle (40),

- detecting presence and/or type of a washing agent possibly present in the receptacle (40) as a function of a value representative of electrical capacity between the single detection electrode (Jd) and the washing agent possibly present in the receptacle (40).

14. A sensor device for detecting presence and/or type of a washing agent possibly contained in a receptacle (40) of a washing agent dispenser (1) for dishwashers, the sensor device (50) having at least one sensitive part that is configured for tdetection of electrical capacity, wherein the at least one sensitive part comprises at least one single detection electrode (Jd), prearranged for mounting outside the receptacle (40) in a contiguous or side by side position with respect to a first wall (40b) of a plurality of walls (40b- 40d) delimiting the receptacle (40), and wherein the sensor device (50) comprises a control circuit (MC) to which the at least one single detection electrode (Jd) is connectable in signal communication, the control circuit (MC) being configured to detect presence and/or type of a washing agent possibly present in the receptacle (40) as a function of a first value representative of electrical capacity between the single detection electrode (Jd ) and the washing agent possibly present in the receptacle (40).

15. A sensor device for detecting presence and/or type of a washing agent possibly contained in a receptacle (40) of a washing agent dispenser (1) for dishwashers, the sensor device (50) having at least one sensitive part which is configured for detection of electrical capacity and which comprises at least one detection electrode (Jd), wherein the sensor device (50) comprises a circuit support (51) on which there are provided:

- the detection electrode (Jd),

- a reference electrode (Jr),

- an auxiliary control electrode (Jn), which is arranged in a position close to the detection electrode (Jd), preferably in such a way as to surround at least part of the detection electrode (Jd),

- a control circuit (MC) to which the detection electrode (Jd), the reference electrode (Jr) and the auxiliary control electrode (Jn) are connectable in signal communication, wherein the circuit support (51) is prearranged for mounting outside the receptacle (40), with the detection electrode (Jd) in a contiguous or side by side position with respect to a first wall (40b) of a plurality of walls (40b-40d) that delimit the receptacle (40), and with the reference electrode (Jr) in a position which is not contiguous or side by side with respect to the walls of the plurality of walls (40a-40d) that delimit the receptacle (40), the control circuit (MC) being configured to detect presence and/or type of a washing agent possibly present in the receptacle (40) as a function of a first value representative of electrical capacity that is acquired by means of the at least one detection electrode (Jd) and the auxiliary control electrode (Jn), and which is compensated as a function of a second value representative of electrical capacity acquired via the reference electrode (Jr).

16. A washing agent dispenser (1) for dishwashers, comprising a sensor device (50) according to Claim 14 or Claim 15.