FR2940037A1 - Domestic dishwasher, has door for closing opening formed on front face of washing tank, control unit controlling dishwasher, and detergent dispenser communicating with control unit and including capacitive sensor device - Google Patents

Abstract

The dishwasher (1) has a door (4) for closing an opening (7) formed on a front face (3) of a washing tank (2) for loading and unloading of crockery. A control unit controls the dishwasher, and a detergent dispenser communicates with the control unit and includes a capacitive sensor device. Two electrodes of the sensor device are placed around a detergent reception zone of the dispenser, and are consisted by electrically insulated metal armatures that are covered by a plastic layer. The dispenser is supplied with electric power by an electric power supply device i.e. accumulator.

Description

The present invention relates to a dishwashing machine comprising a detergent dispenser. In general, the present invention relates to domestic dishwashing machines in which a detergent dispenser must be introduced for use in different washing and rinsing phases. On the one hand, there are known electrically operated dispensers for opening, at a given moment in a washing phase, the detergent receptacle so that the detergent is introduced into the bath water. This type of distributor requires the presence of an electric lock and is therefore relatively expensive. In addition, the detergent is directly introduced into the wash water and dissolves immediately. Mechanical distributors are known in which the distribution of the detergent is carried out when watering the detergent with water. However, these mechanical detergent dispensers have the disadvantage of having several housings depending on the type of detergent used, and in particular a housing for powdered laundry or liquid and a different receptacle for compact powdered powder type pellet. In addition, the dishwashing machines already known have the disadvantage of making complex and technical adjustments by the user through the control means of said machines, in particular as regards the parameterization to be performed according to the type of detergent. used and the hardness of the water. Therefore, the instructions for use of dishwashing machines are complex and include a voluminous amount of information. These instructions for use are not easy to read and the manipulations of the control means of the dishwashing machines are not intuitive. The user of a dishwashing machine is generally required to indicate in the operating parameters thereof the type of detergent used and also to choose the type of result desired, either a drying performance or a cleaning performance.

In addition, the settings are often made once during the installation of the dishwasher and are not updated when the user changes the type of detergent during the life of use of said machine. The present invention aims to solve the aforementioned drawbacks and to provide a dishwashing machine for having a detergent dispenser adapted to communicate with a control unit of said machine so as to detect the type of detergent used, and possibly to display it on said machine. For this purpose, the present invention is directed to a dishwashing machine comprising a door closing an opening on the end face of a washing tub for loading and unloading the dishes, a control unit of said machine, a detergent dispenser. According to the invention, said detergent dispenser is adapted to communicate with said control unit of said machine; said detergent dispenser comprises a capacitive sensor device; and said capacitive sensor device comprises at least two electrodes arranged around a detergent receiving area of said detergent dispenser. Thus, many tedious and restrictive settings mentioned above can be facilitated or even eliminated while making easier the understanding of the manipulations to be performed by the user to adjust the operating parameters of the dishwashing machine. The capacitive sensor device may be adapted to automatically detect the type of detergent, and in particular to determine whether or not a detergent tablet has been introduced into the detergent dispenser, so as to suppress at least one programming step relating to the detergent dispenser. use or not of detergent tablets. When first using the dishwashing machine with a type of detergent or when changing the type of detergent during the life of use of said machine, the control unit of said machine can adapt these operating parameters stand alone or even warn the user of the detection of a type of detergent not previously used from the data collected by the capacitive sensor device. In addition, since the detergent dispenser is adapted to communicate with the control unit of the dishwashing machine, said control unit is adapted to detect by means of the capacitive sensor device: if detergent is present or no in the detergent dispenser receiving area of the detergent dispenser regardless of the type of detergent: dispersed or compacted powder such as pellets, which liquid may be in gel form; if the discharged detergent, especially powdered or liquid, in the detergent receiving area of the detergent dispenser is overdose or underdosing. The detergent dispenser receiving area can thus be adapted to accommodate all types of detergent, including dispersed or compacted powders and gel-like liquid detergents. The capacitive sensor device comprising at least two electrodes disposed around a detergent dispenser receiving area is adapted to detect a type of dispersed or compacted liquid detergent, or liquid. The value of the equivalent capacity of the detergent varies depending on the nature of the detergent present in the detergent dispenser. The equivalent capacity value of the detergent present in the detergent dispenser is linearly proportional to the relative dielectric permittivity of the detergent. Practically, said at least two electrodes of said capacitive sensor device are constituted by at least electrically insulated metal frames. Thus, said electrically insulated metal frames form said at least two electrodes of the capacitive sensor device constituting a planar capacitor. According to a preferred feature of the invention, said detergent dispenser 15 also comprises an infrared sensor device adapted to detect a threshold level of detergent. Thus, the detergent dispenser includes a capacitive sensor device associated with an infrared sensor device. The infrared sensor device is adapted to detect a detergent threshold level in the detergent dispenser. The threshold level of detergent in the detergent dispenser is defined by a height. The infrared sensor device detects a detergent height relative to a predetermined maximum height. The infrared sensor device thus forms a barrier whose light beam can be cut off by the detergent introduced into the detergent dispenser. In this way, the infrared sensor device makes it possible to detect an overdose of detergent by exceeding the predetermined maximum height when it is a detergent in the form of powder or liquid or gel. Furthermore, the infrared sensor device makes it possible to detect the presence of a detergent tablet by exceeding the predetermined maximum height for detergents in the form of powder or liquid or gel. Other features and advantages will become apparent in the description below. In the accompanying drawings, given by way of nonlimiting example: FIG. 1 is a perspective view illustrating a dishwashing machine according to an embodiment of the invention; and Figure 2 is a schematic view illustrating a detergent dispenser 2940037 -4- according to one embodiment of the invention. We will first describe, with reference to Figure 1, a dishwasher washing machine according to the invention. A dishwashing machine 1 comprises a tank 2 whose front face 3 is closed by a door 4. The tank 2 is surrounded by a housing 5 comprising an upper wall 5a, side walls 5b, a bottom wall and a lower wall. The tank 2 comprises at least one means for spraying water (not shown) with a bath of washing and / or rinsing liquid on the dishes. A water of a washing and rinsing liquid bath is defined as water 10 for cleaning the dishes and circulating in a hydraulic circuit of a dishwashing machine 1. The origin of the water a bath of washing and / or rinsing liquid is a water coming from the supply network of the dishwashing machine 1. The tank 2 comprises an upper wall, side walls 2a, a bottom wall and a bottom wall 2b. The housing 5 of the dishwashing machine 1 is adapted to house the tank 2. Said tank 2 is adapted in particular to contain the water of the washing liquid bath and / or rinsing the phases of a cleaning cycle . At least one dish rack 6a, 6b is mounted inside the tank 2. A dish rack 6a located in the upper part of the tank 2 is designated upper basket 20 and a dish rack 6b located in the part bottom of the tank 2 and designated by lower basket. The dish baskets 6a, 6b can be pushed and removed by sliding them inside the bowl 2 of the dishwashing machine 1 either at the end of a cleaning cycle for unloading the dishes or at the end of a cleaning cycle. beginning of the cleaning cycle for loading the dishes. This dishwashing machine 1 is provided with a pump (not shown) for the circulation of the water of the washing liquid and / or rinsing bath in the tank 2. Control means (not shown) make it possible to run predetermined cleaning programs. The door 4 of the tank 2 makes it possible to close an opening 7 made in the tank 2. This door 4 of the tank 2 can thus be movable between a closed position in which it closes the opening 7, in a sealed manner, and a position opened. In this embodiment, and in no way limiting, the tank door 4 is pivotally mounted about an axis of rotation integral with the casing 5 of the dishwashing machine 1. This dishwashing machine 1 comprises a door 4 formed in particular of two parts. The first part of the door 4 corresponds to the external facade 4a visible 2940037 -5- by the customer. Said facade 4a can also be a panel adapted to receive a piece of furniture of the kitchen. The second part of the door 4 is the counter door 4b, that is to say the inner wall of the door 4 closing the tank 2. In the embodiment, the dishwashing machine 1 operates such This minimizes the volume of the bath of washing and / or rinsing liquid retained in a sump 8 formed in the bottom wall 2b of the tank 2 from the spraying means. The water circulation pump draws water from the bath of washing and / or rinsing liquid into the sump 8 to circulate said water from the washing liquid and / or pressurized rinse bath to the water cleaning means. spray. Then, the bath of washing and / or rinsing liquid returns to the sump 8. The water circulation pump is driven by an electric motor. The open or closed state of a water supply solenoid valve of the washing tub 2 depends on the amount of water retained in said wash tub 2. This quantity of water must be sufficient to ensure the proper operation of the water circulation pump without defusing. The state, open or closed, of the solenoid valve depends on the amount of water retained in the tank 2. This dishwashing machine 1 is provided with a pump (not shown) 20 to empty the bath water washing liquid and / or rinsing the tank 2 to a wastewater network connected to said dishwashing machine 1. The drain pump draws water from the bath of washing and / or rinsing liquid in the sump 8 for discharging said water from the bath of washing and / or rinsing liquid to a wastewater network connected to the dishwashing machine 1. The drain pump is driven by an electric motor. A detergent dispenser of a dishwashing machine according to the invention will now be described with reference to FIG. The detergent dispenser 9 is adapted to communicate with the control unit (not shown) of the machine 1. The detergent dispenser 9 comprises a capacitive sensor device 10. The capacitive sensor device 10 comprises at least two electrodes 11 disposed around a detergent dispenser receiving area 9a of the detergent dispenser 9. Thus, many of the fastidious and restrictive settings mentioned above can be facilitated or even eliminated while making it easier to understand the manipulations to be performed by the user to solve the problem. the operating parameters of the dishwashing machine 1. When using the dishwashing machine 1 for the first time with a type of detergent or when changing the type of detergent in the course of life of use of said machine 1, the control unit of said machine 1 can adapt these operating parameters independently. me or even warn the user of the detection of a type of detergent not previously used from the data collected by the capacitive sensor device 10. Preferably, said at least two electrodes 11 of the capacitive sensor device 10 are arranged along two opposite walls of the detergent receiving area 9a of the detergent dispenser 9. In addition, since the detergent dispenser 9 is adapted to communicate with the control unit of the dishwashing machine 1, said control unit is adapted to detect by means of the capacitive sensor device 10: whether detergent is present or not in the detergent receiving area 9a of the detergent dispenser 9 regardless of the type of detergent: dispersed powder or compacted such as pellets, which liquid may be in gel form; if the detergent spilled, especially powdered or liquid, in the detergent receiving area 9a of the detergent dispenser 9 is overdosed or dosed. The control unit of the machine 1 may comprise a control electronic card on which a microcontroller is mounted so as to control said machine 1 according to the predetermined operating programs. The control unit of the machine 1 can be positioned, for example, above the washing tub 2 or in the washing tub door 4. The detergent dispensing area 9a of the detergent dispenser 9 can be suitable for receiving all types of detergent, including dispersed or compacted powders and liquid detergents which may be in gel form. In one embodiment, the detergent dispenser receiving area 9a may be generally in the form of a box defined by four peripheral walls 12, to be arranged vertically when using detergent 9, and a bottom wall 13 for sealing one side of the box. On a face opposite to the bottom wall 13, the box may comprise a lid (not shown). One of the walls of the box may be adapted to receive water introduction means (not shown) in the detergent receiving area 9a of the detergent dispenser 9. These means for introducing water into the dispensing zone. The detergent dispenser 9 may, for example, be constituted by a pipe 2940037 for conveying water to an opening in one of the walls of the box. The water supply to the detergent dispenser receiving area 9a of the detergent dispenser 9 may be effected otherwise than by a direct supply, and especially from water jets from the water spraying means used in a machine. In addition, the water supply can be controlled mechanically, electrically, or regulated according to the temperature of a washing bath or rinsing. The detergent dispenser 9 can be fixed to a dish rack 6a, 6b in a removable manner or not, on a sliding slide 14 mounted on a dish rack 6a, 6b allowing the user to extract the receiving area from detergent dispenser 9a for detergent filling, or in counter door 4b of wash tank door 4. Of course, the shape of the detergent receiving area 9a and the location of the dispenser detergent 9 are only given as non-limiting examples. The capacitive sensor device 10 comprising at least two electrodes 11 disposed around a detergent receiving area 9a of the detergent dispenser 9 is adapted to detect a type of dispersed or compacted powder detergent, or liquid. The capacitive sensor device 10 may also include a printed circuit board adapted to communicate with the control unit of the machine 1. This printed circuit board is advantageously arranged in a sealed housing. Said printed circuit board of the capacitive sensor device 10 can be placed either in the detergent dispenser 9 or in the door 4 so as to communicate data between said detergent dispenser 9 and the control unit of the machine 1 Said at least two electrodes 11 of the capacitive sensor device 10 are preferably arranged along two opposite peripheral walls 12 of the detergent dispenser box 9. Practically, said at least two electrodes 11 of said capacitive sensor device 10 are constituted by at least electrically insulated metal frames. Thus, said electrically insulated metal frames form said at least two electrodes 11 of the capacitive sensor device 10 constituting a planar capacitor whose value is defined by the following formula: C = eo.er. S e C: value of a plane capacitor; eo: dielectric constant of the vacuum;

er: dielectric constant of the material separating the electrodes; S: surface of the electrodes opposite;

e: thickness of the dielectric separating the two electrodes;

Digital application with the following assumptions:

er (air) = 1; (water) = 80; eo = 8.84 × 1042, S = 800 mm 2, e = 45 mm

In the case where the detergent receiving area 9a of the detergent dispenser 9 is empty, er (air) = 1, then: Cair = eo. S = 0.16pF

In the case where the detergent receiving zone 9a of the detergent dispenser 9 is filled with water, er (water) = 80, then: S Ceau = eo.er.u = er.Cair = 80 Cair = 12.6pF e In the case where the detergent receiving area 9a of the detergent dispenser 9 is partially filled with water, then the capacitor seen by the electrodes 11 is equivalent to two capacitors in parallel: SI S2 Ceq = eo + eo. st. The value of the capacitor can thus be in the range 0.1 micron to 13 micron depending on the detergent height present in the detergent dispenser 9 for the exemplary embodiment of the invention presented above.

The value of the capacitor is of the order of: for a detergent in gel form: Cget = 8O.Cair The dielectric permittivity of water is one of the largest and its value is of the order of er (water) = 80. The gel detergent consists essentially of water. Then, the dielectric permittivity of the detergent in gel form is very close to that of water. Therefore, the value of the condenser of a detergent in gel form is substantially equal to that of the water condenser.

In the case of a complete filling of the receiving zone 9a of a detergent dispenser 9 with a detergent in gel form, the value of the capacitor is of the order of 12.6pF. The capacitor value can vary between 0.1 μF and 13 μF depending on the amount of gel detergent contained in the receiving area 9a of the detergent dispenser 9. for a detergent in the form of powder: Cpoudre = 5.Cair 5 Generally, the value of the dielectric permittivity of an insulating element such as detergent in the form of powder is of the order of er (powder) = 5. In the case of a complete filling of the receiving zone 9a of a detergent dispenser 9 with a detergent in gel form, the value of the capacitor is of the order of 1pF. The capacitor value can vary between 0.1 pF and 1 pF depending on the amount of detergent powder contained in the receiving area 9a of the detergent dispenser 9. Advantageously, the electrically insulated metal frames are covered by a plastic layer. Thus, the metal reinforcements are electrically isolated in a simple and inexpensive manner, such as for example by an overmoulding process. The metal frames electrically insulated from the detergent dispenser 9 are disposed facing each other and constitute two opposite walls 12 of the detergent receiving area 9a. In one embodiment of the invention, the electrically insulated metal frames and the detergent receiving area 9a of the detergent dispenser 9 are disposed within said wash tub 2. And the communication between the detergent dispenser 9 and the control unit of the machine 1 is made by a wireless link, preferably by radio frequency or optical. In this embodiment, the detergent dispenser 9 comprises an electronic system for at least sending information to the control unit of the machine 1, either directly or indirectly. This electronic system of the detergent dispenser 9 can also be adapted to receive information from the control unit of the machine 1. When the communication between the detergent dispenser 9 and the control unit of the machine 1 is performed by a radiofrequency link, at least a portion of the washing tub 2 must be transparent to the radio waves. Said at least part of the washing tub 2 transparent to radio waves can be made of plastic. Said at least a portion of the washing tub 2 transparent to radio waves may be the upper wall of said washing tub 2 since the latter may be located near the control unit of the machine. Thus, the communication between the detergent dispenser 9 and the control unit of the machine 1 can be carried out permanently. Such radiofrequency communication between the detergent dispenser 9 and the control unit of the machine 1 makes it possible to indicate information to the user, for example by a display or light-emitting diodes, concerning the operating state of the dispenser. detergent 9 when the door 4 of the washing tub 2 is open. The information indicated to the user through display means controlled by the control unit of the machine 1 can be arranged on an upper wall 4c of the door 4 of the washing tub 2 so as to be visible when said door 4 is ajar, or on a control panel on the front. Such radiofrequency communication between the detergent dispenser 9 and the control unit of the machine 1 makes it possible to produce a unidirectional connection, for example by means of a transmitter at the level of the detergent dispenser 9 and a receiver at the level of the of the control unit, or a bidirectional link, for example by means of two transceivers. When the communication between the detergent dispenser 9 and the control unit of the machine 1 is performed by an optical link, a visual coding can be made from several light-emitting diodes. In this way, a binary coding can be implemented and make it possible to send information to the control unit of the machine 1. For example, the use of two light-emitting diodes makes it possible to obtain four operating states. A receiving device may be arranged in the counter door 4b of the door 4 of the washing tub 2 and facing the detergent dispenser 9 mounted inside the washing tub 2, for example on a dish rack 6a, 6b. The data emitted by the light-emitting diodes assembled on the detergent dispenser 9 are read by the receiving device when the door 4 of the washing tub 2 is closed, then this data is sent to the control unit of the machine 1. When the communication between the detergent dispenser 9 and the control unit of the machine 1 is performed by an optical link, an infrared link can be implemented between the detergent dispenser 9 and the control unit of the machine 1 .

An infrared beam emitting device may be installed at the detergent dispenser 9 and a receiving device may be installed at the top wall of the washing tub 2 and in the vicinity of the control unit of the detergent dispenser 9. In this embodiment where the communication between the detergent dispenser 9 and the control unit of the machine 1 is effected by a radiofrequency or optical connection, said detergent dispenser 9 can be supplied with electrical energy by at least one power supply device that can be: at least one battery; at least one accumulator; or at least one active RFID device (acronym for the term radio frequency identification). This device uses markers called radio-tags comprising an antenna associated with an electronic chip that allows them to receive and respond to radio requests sent from the transceiver and a battery allowing them to transmit a signal. The capacitive sensor device 10 is supplied with electrical energy to enable its operation. The power supply of the capacitive sensor device 15 may be identical to that used for the radio frequency or optical link. In the case where the power supply of the detergent dispenser 9 is performed by at least one battery, said at least one battery is inserted into a sealed housing. In this way, the detergent dispenser 9 is energy independent. In the case where the power supply of the detergent dispenser 9 is provided by at least one accumulator, the at least one accumulator is inserted in a sealed housing. In this way, the detergent dispenser 9 is energy independent. Advantageously, said at least one accumulator is recharged by a generator actuated by a flow of water supplying the detergent dispenser 9.

For example, the flow of water fed to the detergent dispenser 9 drives a turbine to recharge the at least one accumulator by converting the hydraulic force of the water flow into electrical energy. In the case where the power supply of the detergent dispenser 9 is performed by at least one active RFID device, at least one radio tag is inserted into a sealed housing. In this way, the detergent dispenser 9 is energy independent. In these three cases of power supply of the detergent dispenser 9 mentioned above, a standby mode of the electronic system of the detergent dispenser 9 can be implemented so as to save the energy of the electric power sources. The electronic system of the detergent dispenser 9 can thus be put into operation only during the communication phases between the detergent dispenser 9 and the control unit of the machine 1. The transition from a standby mode to a The active mode of the detergent dispenser electronic system 9 can be controlled by the machine control unit 1. In this embodiment where the communication between the detergent dispenser 9 and the machine control unit 1 is performed by a radiofrequency or optical link, said detergent dispenser 9 can also be supplied with electrical energy by a wire link comprising a sealed contact device. This connection between the detergent dispenser 9 and the control unit of the machine 1 made by means of cables and sealed contacts can be carried out at the rear wall of the washing tub 2. This power supply must therefore to understand a galvanic decoupling. The AC voltage supply is generated by an isolation transformer, wherein said isolation transformer is operable to electrically isolate the capacitive sensor device 10 from the general power supply of the dishwashing machine 1. When the detergent dispenser 9 is mounted in the counter door 4b of the door 4 of the washing tub 2, the power supply can be performed by a wire connection without sealing problem.

The electrical connection between the detergent dispenser 9 and the control unit of the machine 1 can then be performed as known to those skilled in the art where an automatic detergent dispenser with lock is assembled on the counter door 4b of the wash tank door 4 2. In another embodiment of the invention, the door 4 of the washing tub 2 comprises a frontage 4a facing the outside of the machine 1 and a counter-door 4b oriented to the wash tank 2. The electrically insulated metal frames are integrated into the storm door 4b. The electrically insulated metal frames may be, for example, integrated into a plastic part fixed to or belonging to the counter door 4b of the wash tank door 4. The detergent dispenser receiving area 9a of the detergent dispenser 9 is arranged on a support element mounted inside the washing tub 2. The support element of the detergent receiving area 9a of the detergent dispenser 9 may for example be a dish rack 6a, 6b, or a partition wall placed inside the washing tub 2 between two dish baskets 6a, 6b. And the electrically insulated metal reinforcements integrated in the counter door 4b are positioned opposite the detergent receiving area 9a of the detergent dispenser 9 when closing the door 4 of the washing tub 2. Thus , the portion of the detergent dispenser 9 for detecting the type of detergent housed in the detergent receiving area 9a is integral with the counter door 4b of the wash tank door 4. When closing the door 4 of the washing tub 2, the plastic part of the counter door 4b having the electrically insulated metal frames surrounds the detergent receiving area 9a of the detergent dispenser 9, at least on two opposite sides 12. communication between the electrically insulated metal frames of the detergent dispenser 9 and the control unit of the machine 1 is performed by a wire connection. In this way, detection of the type of detergent in the detergent receiving area 9a of the detergent dispenser 9 can be carried out while avoiding the problems of sealing the power supply and transmitting a signal to the detergent dispenser 9. the control unit of the machine 1 since the electrically insulated metal frames are connected by wiring to the control unit of the machine 1 through the door 4.

In an improved embodiment of the invention, said detergent dispenser 9 also includes an infrared sensor device (not shown) adapted to detect a detergent threshold level. Thus, the detergent dispenser 9 includes a capacitive sensor device 10 associated with an infrared sensor device.

The infrared sensor device is adapted to detect a threshold level of detergent in the detergent dispenser 9. The threshold level of detergent in the detergent dispenser 9 is defined by a height. The infrared sensor device detects a detergent height relative to a predetermined maximum height.

The infrared sensor device thus forms a barrier whose light beam can be cut off by the detergent introduced into the detergent dispenser 9. In this way, the infrared sensor device makes it possible to detect an overdose of detergent by exceeding the height. predetermined maximum when it is a detergent in the form of powder or liquid or gel.

Furthermore, the infrared sensor device makes it possible to detect the presence of a detergent tablet by exceeding the predetermined maximum height for detergents in the form of powder or liquid or gel. The infrared sensor device may comprise a power supply system and a communication system with the control unit of the machine 1 identical to that of the capacitive sensor device 9. The infrared sensor device may be equipped at least one element 5 for transmitting a light beam and at least one receiving element, or one or more transmission and reception elements. The infrared sensor device may also include at least one reflection element of a light beam so as to reflect the light beam to a receiving member. The detection of detergent in the form of powder, liquid, gel, or tablet 10 can thus be achieved by the interruption of the light beam emitted by the infrared sensor device and by the detection of the capacitive sensor device 10. , the control unit of the machine 1 is adapted to control display means, such as for example a display or lights, so as to inform the user on the type of detergent detected in the detergent dispenser 9 and or the filling level of the receiving zone 9a of said detergent dispenser 9.

Claims (10)

CLAIMS 1- Dishwashing machine (1) comprising a door (4) closing an opening (7) provided on the end face (3) of a washing tub (2) for loading and unloading the dishes, a unit controlling said machine (1), a detergent dispenser (9), characterized in that: said detergent dispenser (9) is adapted to communicate with said control unit of said machine (1); said detergent dispenser (9) comprises a capacitive sensor device (10); and said capacitive sensor device (10) comprises at least two electrodes (11) disposed around a detergent receiving area (9a) of said detergent dispenser (9). 2- Dish washing machine (1) according to claim 1, characterized in that said at least two electrodes (11) of said capacitive sensor device (10) are constituted by at least electrically insulated metal frames. 3- Dish washing machine (1) according to claim 2, characterized in that said electrically insulated metal frames are covered by a layer of plastic material. 4- Dishwashing machine (1) according to claim 2 or 3, characterized in that: said electrically insulated metal frames and said detergent receiving area (9a) of said detergent dispenser (9) are arranged inside said washing tub (2); and - the communication between said detergent dispenser (9) and said control unit of said machine (1) is performed by a wireless link, preferably by radiofrequency or optical. 5- Dishwashing machine (1) according to claim 4, characterized in that said detergent dispenser (9) is supplied with electrical energy by at least one power supply device. 6- dishwashing machine (1) according to claim 5, characterized in that said at least one power supply device is at least one accumulator, and said at least one accumulator being recharged by a generator powered by a flow of water supplying said detergent dispenser (9). 7- dishwashing machine (1) according to claim 4, characterized in that said detergent dispenser (9) is supplied with electrical energy by a wire connection comprising a sealed contact device. 2940037 -16- 8- Dishwashing machine (1) according to claim 2 or 3, characterized in that: said door (4) of said washing tub (2) comprises a facade (4a) facing outwardly of said machine ( 1) and a counter-door (4b) facing said washing tub (2); said electrically insulated metal frames are integrated in said counter door (4b); said detergent receiving area (9a) of said detergent dispenser (9) is disposed on a support member (6a, 6b) mounted within said wash tub (2); and said electrically insulated metal reinforcements integrated in said counter-door (4b) are positioned facing said detergent receiving zone (9a) of said detergent dispenser (9) upon closure of said door (4) of said tank of washing (2). 15 9- Dishwashing machine (1) according to claim 8, characterized in that the communication between said metal frames electrically insulated from said detergent dispenser (9) and said control unit of said machine (1) is achieved by a connection wired. 10- Dishwashing machine (1) according to any one of claims 1 to 9, characterized in that said detergent dispenser (9) also comprises an infrared sensor device adapted to detect a threshold level of detergent.