WO2008047216A2

WO2008047216A2 - A washing machine, particularly a laundry washing machine, with simplified user interface

Info

Publication number: WO2008047216A2
Application number: PCT/IB2007/003100
Authority: WO
Inventors: Elisabetta Ainardi; Savio La Bella; Alessandro Menghi
Original assignee: Indesit Company S.P.A.
Priority date: 2006-10-17
Filing date: 2007-10-17
Publication date: 2008-04-24
Also published as: PL2079867T3; EP2079867A2; WO2008047216A3; DE602007006537D1; ES2342439T3; EP2079867B1; ATE467707T1; ITTO20060748A1

Abstract

A washing machine comprises a wash tub (3), charging means (7, 8) for delivering a liquid into the tub (3), draining means (10, 12) for evacuating the liquid from the tub (3), a device for dispensing washing agents (6), and a control system (13, 14, 17). The control system (13, 14, 17) comprises at least: - a control unit (14), configured for managing a plurality of treatment cycles that can be carried out by the machine (1); - memory means (16), in which management programs of the treatment cycles are stored; - programming means (13), for making a manual selection among a plurality of possible selections (13b-13e), there being associated to each selection that can be made via the programming means (13) at least one respective management program; - means (17) for detecting a characteristic of the liquid charged into the tub (3). The control system (13, 14, 17) is designed in such a way that associated to a selection (13b) that can be made via the programming means (13) are two different management programs, corresponding to two different treatment cycles, and the control unit (14) is configured for carrying out one or other of the aforesaid management programs according to a value of said characteristic, obtained via the detection means (17) following upon a first charging of liquid into the tub (3).

Description

"A washing machine, particularly a laundry washing machine, with simplified user interface"

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TEXT OF THE DESCRIPTION Field of the invention

The present invention relates to a household washing machine, particularly a laundry washing machine, according to the preamble of Claim 1.

State of the prior art

A machine of the type referred to is known from the document No. EP-B-O 666 358. In this solution, the machine is equipped with detection means, which, in the initial phase of a washing cycle previously started, detect the possible presence of detergent in the liquid charged into the tub. hi said initial phase of the cycle, clean water drawn from the water mains is made to pass through a specific compartment of the dispenser of washing agents, and in particular the compartment designed to contain a pre- washing detergent. The control unit of the machine, depending on the result of the measurement made via the detection means, modifies the performance of the washing cycle in progress. In practice, in the case where, in the water taken in during the aforesaid initial phase, there is not detected the presence of detergent, the control unit of the machine does not carry out pre-washing, passing immediately to execution of a phase of washing in a strict sense; instead, in the case where the presence of detergent in the water taken in is detected, the control unit issues a command for carrying out the cycle completely, i.e., the cycle that comprises pre-washing. The document in question describes some further possible applications of the system for detecting the possible presence of detergent in the water, with a view to limiting the negative consequences deriving from errors committed by the user of the machine in relation to the use of washing agents.

A washing machine according to the preamble of Claim 1 is also known from the document No. EP-B-O 748 892. In this case the control system of the machine is prearranged in such a way that, in the conclusive part of a treatment cycle, the rinsing of the washing will proceed until a pre-determined rinsing performance has been achieved, as detected depending on measurements of ion concentration of the water used, obtained via detection means. In practice, then, when the value of ion concentration detected - which represents the presence of detergent in the water - drops below a given threshold, rinsing is completed. The solution described in the above document envisages the possibility for the user to set the aforesaid threshold value, according to his or her requirements.

It is known that, in the most widely used washing appliances, the manual programming means comprise a plurality of keys or push-buttons, or else a rotary selector with a number of alternative positions, or else a display of a touch-screen type.

Irrespective of their type, the programming means provided must be conceived for enabling the user to make a convenient selection between a plurality of possible selections, associated to each of which is execution of a given treatment cycle. Consider, for example, the case of a washing machine of the type indicated and designed for carrying out five different cycles of treatment of the washing. The so-called "user-interface" of the machine, via which the user can select the desired treatment cycle between the five possible ones, must be equipped with at least five keys/push-buttons, or else with a selector with at least five positions, or else with a display that is sufficiently large to highlight clearly the symbols representing the five treatment cycles that can be selected. The overall dimensions and the complexity of construction and use of the user interface are, at least to a certain extent, proportional to the number of selections allowed.

It should moreover be recalled that washing machines have been proposed with an electronic control system provided for selecting automatically the treatment cycle to which the washing is to be subjected. In this case, the machine envisages just one control means, which corresponds to a push-button for starting the washing cycle, and the user is not required to make any selection. However, not all users are willing to accept such an approach, according to which the washing appliance "dominates" the user.

Summary of the invention

The present invention has thus been developed with a view to simplifying the activity of selection of a treatment cycle by a user in the case of machines equipped with manual programming means. From a different standpoint, the invention has been developed with a view to simplifying the construction, appearance, and overall dimensions of the manual programming means, i.e., the user interface.

Said purposes are achieved, according to the present invention, by a washing appliance, particularly a laundry washing machine, having the characteristics specified in the annexed claim 1. Preferred characteristics of the machine forming the subject of the invention are specified in the sub-claims. The claims form an integral part of the technical teaching provided herein in relation to the invention.

Brief description of the drawings

Further purposes, characteristics, and advantages of the present invention will emerge clearly from the ensuing description, made with reference to the annexed plates of drawings, which are provided purely by way of non-limiting example and in which: - Figure 1 is a schematic representation of a washing appliance according to the present invention; and

- Figure 2 is a simplified diagram of a measuring arrangement for the machine of Figure 1.

Detailed description of preferred embodiments of the invention

Represented schematically in Figure 1 is a washing appliance according to the invention, designated as a whole by 1. In the case exemplified, the appliance 1 is a laundry washing machine that comprises a cabinet 2, within which a tub 3 is supported in a known way. Mounted rotatably within the tub 3 is a drum 4 for the washing, which can be driven in rotation via an electrical motor 5. The drum 4 is accessible to the user by means of an opening, which is made in the cabinet 2 and is closed, during operation of the machine 1, by a door.

Designated as a whole by 6 is a dispenser of washing agents, which is assumed herein as being of the type having a drawer defining three single-dose compartments for containing the respective washing agents, and in particular a compartment 6a for a pre-washing detergent, a compartment 6b for a washing detergent, and a compartment 6c for a softening agent or a bleaching agent. The aforesaid drawer is housed slidably in a hopper container, having a lower outlet that is connected, via a pipe 7, to the tub 3. Alternatively, the dispenser of washing agents can be housed within the door of the machine 1 and can comprise one or more compartments, preferably three compartments.

Designated by 8 are valve means, having an inlet designed for connection to a domestic system 9 for supply of clean water. The dispenser 6 and the valve means 8 are provided to get a flow of water coming from the water-supply system 9 to pass, selectively and in a controlled way, through one of the compartments 6a, 6b, or 6c, depending on the operating phase of the machine 1. The water, after traversing the compartment concerned, comes out of the aforesaid hopper container, entraining along with it the possible washing agent, and then reaches the tub 3 via the pipe 7. According to techniques widely known in the field, the valve means 8 can comprise a single solenoid valve, and the dispenser 6 can be equipped with a movable nozzle, which can be controlled for directing the flow allowed by the solenoid valve selectively to one of the compartments 6a-6c; in another possible embodiment of a known type, the valve means can comprise a system of a number of solenoid valves in parallel.

Designated by 10 is a drain pipe, having a first end connected to an opening present in the lower region of the tub 3 and a second end designed for connection to a sewage system 11. Provided along the pipe 10 is a drain pump 12.

Designated as a whole by 13 are the manual programming means of the machine 1, i.e., its user interface. In the case exemplified, said interface comprises five keys, and in particular a key for turning-on/tuming-off, designated by 13 a, and four keys 13b-13e for selection of the treatment cycles that can be carried out by the machine 1.

Designated as a whole by 14 is a control unit of the machine 1, comprising a microcontroller 15. The microcontroller 15 in turn comprises, or operatively connected thereto are, non- volatile memory means, designated by 16, for example, comprising one or more ROMs and/or EPROMs and/or EEPROMs and/or Flash memories.

Designated as a whole by 17 are detection means, which are adapted to detect directly or indirectly one or more chemical/physical characteristics of the water present in the tub 3 during operation of the machine. In one possible embodiment, the detection means 17 comprise a circuit arrangement designed to measure the degree of resistivity, or else of conductivity, of the water, and thus obtain indirectly, from the degree of resistivity or conductivity measured, the value of alkalinity or of ion concentration of the water, said value representing the concentration of detergent. The alkalinity or ion concentration of the water can also be measured directly, as is possible by measuring other chemical/physical characteristics that can be affected by the presence of washing agents in the water, such as, for example, the hardness or turbidity.

In the preferred embodiment of the invention, the aforesaid circuit arrangement is of the same type as the one described in the aforesaid documents EP-A-O 666 358 and EP-A-O 748 892, and again in EP-B-582326, whose teachings are incorporated herein for reference, hi brief, as may be seen in Figure 2, the aforesaid arrangement comprises two electrodes, designated by A and B, constituted by electrically conductive elements, which are adapted to come into contact with the water charged into the tub, the electrode B being isolated from the electrode A. In the case exemplified, the electrodes A and B are positioned in the proximity of the lower opening of the tub 3, i.e., in the proximity of the inlet 3a of the drain pipe 10.

By connecting the electrode A to the positive pole of a generator E of a.c. voltage (for example, E = 5 V or else E = 3.3V) and setting the electrode B to ground (negative pole of the same generator of voltage E) via a capacitor C of appropriate capacitance (for example, C = I μF), there is determined a flow of current from A to B that is proportional to the resistivity of the washing water. Said flow of current comes to supply the charging transient of the capacitor C and is stopped when said transient ceases, i.e., when a voltage equal to the value of E is present across the capacitor C. The duration of the charging transient depends upon the value of the capacitance of the capacitor C and upon the value of the resistivity of the means (the water) through which the charging current flows. Once an appropriate capacitance of the capacitor C has been set (for example, C = 1 μF), it is possible to obtain information on the resistivity of the water through the measurement of the duration of the time of charging of said capacitor C. The measurement of the duration of the time of charging is made via the microcontroller 15 of the control unit 14, equipped with an internal clock that is able to measure the time with a good resolution (for example, with a resolution of 1 μs). A digital input of the microcontroller 15, designated by INP in Figure 2, is connected at the ends of the capacitor C, whilst one of its digital outputs, designated by OUT, is used for driving a transistor Q, used as on/off switch, the collector of which is in turn connected to the ends of the capacitor C. The measurement of the time of charging of the capacitor C is made via the following operations of the microcontroller 15:

- fast discharging of the capacitor C, obtained by applying a brief pulse (for example, of the duration of 1 ms) to the base of the transistor Q via the output OUT;

- start of counting of the time at the instant in which, once the discharging pulse of the capacitor ceases, the transistor Q returns to the state of inhibition, thus enabling start of charging of the capacitor itself;

- interruption of the counting of the time at the instant in which the voltage across the capacitor reaches the threshold for triggering the digital input INP, the value of which is typically half that of the supply voltage of the microcontroller 15 (i.e., E/2 = 2.5 V or else E/2 = 1.65 V);

- the value reached by the time counter present within the microcontroller 15, at the instant of the interruption of the count, constitutes the result of the measurement and is in a direct relation with the characteristics of resistivity of the water. The microcontroller 15 is appropriately programmed, and has available for said purpose an adequate knowledge base encoded in the memory means of the microcontroller, to make the calculation of the resistivity presented by the water following upon measurement of the time of charging of the capacitor C. The value of the alkalinity or ion concentration in the water, which is indicative of the concentration of detergent, is obtained from the microcontroller 15, via the knowledge base stored, on the basis of the measurement of the resistivity (or of the conductivity) of the liquid.

To return to Figure 1, stored in the memory means 16 are the programs of operation or management, which supervise execution of the treatment cycles that can be carried out by the machine. In said memory means 16 there are obviously encoded also the instructions regarding the general functions of the machine 1, including control of the measuring arrangement represented in Figure 2. Of course, the machine 1 also comprises all the other components necessary for its normal operation (level sensors, resistor for heating the water, filters, door, safety devices, etc.), which are not represented and described herein in so far as they are not of immediate interest for the purposes of the present invention.

It may be assumed, for reasons of simplicity, that the machine 1 is designed for carrying out the following five different treatment cycles: a) a cycle for washing coloureds; b) a cycle for washing synthetic garments; c) a strong cycle, for washing resistant and/or very dirty garments; d) a fast cycle, for washing garments that are not veiy dirty; and e) a rinsing cycle, for elimination of residue of detergent from pre-treated garments, for example, hand-washed garments.

In another example, the five different treatment cycles may be: a) a cycle specifically designed for washing garments made of cotton; b) a cycle specifically designed for washing garments made of synthetic material; c) a cycle specifically designed for washing delicate garments, such as, for example, garments made of silk, or woollens; d) a fast cycle, for washing garments that are not very dirty, said cycle having a duration of approximately 30 minutes; and e) a rinsing cycle, for elimination of residue of detergent from pre-treated garments, for example, hand-washed garments.

As in the prior prior art, the cycles a) - d) comprise a plurality of distinct phases, which each envisage an initial charging of water, followed by rotations of the drum, and finally a draining of the water used. Said plurality of phases can comprise at least one or more phases of washing in a strict sense, with introduction of detergent into the tub, one or more rinsing phases, with possible introduction of an additive into the tub, one or more phases of distribution of the laundry load and one or more phases of centrifugation. Some cycles, for example, the cycles a) and c), can also envisage an initial phases of pre-washing, with introduction of detergent into the tub. The cycle e) envisages, instead, one or more phases of rinsing only, possibly with the introduction into the tub of an additive (softener).

Corresponding to each of the aforesaid treatment cycles, present in the memory means 16 is a respective program of operation: in the case exemplified, then, in the memory means 16 there will be encoded five different programs of operation, which are used by the microcontroller 15 and can be carried out by the control unit.

According to a first characteristic of the invention, the control system 14 is provided in such a way that, associated to a selection that can be made via one of the programming keys 13b-13e, are two different programs of operation, corresponding to two different treatment cycles that can be carried out by the machine. In the preferred embodiment of the invention, one of the aforesaid two programs is the one corresponding to the rinsing cycle; the other program can, for example, be the fast cycle. In the non-limiting example described herein, the two aforesaid programs are associated to a pre-determined programming key, which is assumed herein as being the key 13e.

In accordance with a second characteristic of the invention, the control unit 14 is configured for carrying out one or other of the two aforesaid programs as a function of the value of a characteristic of the water present in the tub 3 following upon a first charging from the water-supply system 9, said value being obtained via the detection means 17. hi particular, the aforesaid characteristic is the alkalinity or the ion concentration of the water charged into the tub - obtainable via the detection means 17 in the ways described above - which, as has been said, represents the presence of a washing agent.

In the embodiment currently deemed preferential, the aforesaid initial charging of water into the tub 3 belongs to a specific detection phase, executed under the control of the microcontroller 14 - purposely programmed for this - in the case where the user has pressed the key 13e. The encoded instructions that the microcontroller 15 uses for the purposes of execution of said phase do not belong, however, to the two programs associated to the key 13e: as will appear, said detection phase is executed preliminarily at the start of one or other of the two programs in question and is thus distinct from the corresponding treatment cycles. The preliminary detection phase comprises, as has been said, an initial charging of water from the water mains 9, via the valve means 8, for this purpose controlled by the microcontroller 15 to get the water itself to pass into a pre-defined compartment of the dispenser 6. It is assumed, in what follows, that said predefined compartment is the compartment 6a of the pre-washing detergent. The amount of water charged into the rub is modest, indicatively comprised between 4 and 6 litres, preferably approximately 5 litres. Charging of said amount of water is followed by a step of rotation of the drum 3 containing the washing. Preferably, the rotation occurs in the absence of pause and with constant direction of rotation. The speed of rotation is higher than 70 r.p.m., for example, comprised between 80 and 120 r.p.m., preferably at approximately 90-95 r.p.m.. The preferred speed enables the so-called "satellization" of the laundry load in the drum 4 to be achieved (i.e., the laundry items tend to adhere to the internal wall of the drum 4, by centrifugal force, forming a sort of ring). Thanks to said speed it is possible to achieve, in a relatively short time, repeated passage of laundry items in the water charged into the tub, without causing excessive stresses on to the garments. Indicatively, the step of rotation of the drum has a duration of approximately 3 minutes. At the end of the step of rotation, possibly with the drum 4 being still in motion by inertia, the control unit 14 acquires, via the detection means 17, the value of alkalinity or ion concentration of the water present in the tub. The preliminary detection phase then terminates, with a drain of the water from the tub 3. For this purpose, the control unit 14 controls the drain pump 12: given the relatively modest amount of water present in the tub, complete draining can be obtained in a few seconds, typically 2-3 seconds. The duration of the entire preliminary detection phase is approximately 3-3.5 s.

The detected value of alkalinity/ion concentration is destined to be compared by the microcontroller 15 with a given threshold value, stored in the memory means 16 and, depending on the result of said comparison, the microcontroller discriminates which of the two programs of operation associated to the key 13e is to be executed and then - in the example considered - to which treatment cycle (rinsing cycle or fast cycle) the laundry is to be subjected. In other words, then, after execution of the preliminary detection phase, the control unit will start execution of one of the programs.

The threshold value referred to above can be indicatively comprised between 0.8 and 1.5 milliequivalents (mEq) of alkali per litre: a value of alkalinity that can conveniently be adopted as threshold value is 1.2 mEq of alkali per litre. It should, however, be in any case pointed out that, irrespective of the temperature and the hardness of the water in normal conditions, the difference between the ion concentration of pure water and that of water containing a residue of washing agent is considerable, and that the measuring arrangement of Figure 2 is able to discriminate the two different conditions autonomously and easily.

The operation of the machine 1 , in the example considered herein, is as follows.

The user, after loading the laundry that is to be treated in the drum 4, presses the key 13 a. Let us suppose that the laundry loaded into the machine is pre-treated; i.e., it has already been subjected to washing with a detergent. Said situation occurs typically for hand-washed garments, which a user then wishes to rinse in the machine. Next, the user turns the machine 1 on by pressing the key 13a.

The condition of activation of the key 13e generates a signal that is detected on an input of the microcontroller 15 in accordance with modalities in themselves known. Said signal informs the microcontroller 15, programmed for this, that the aforesaid preliminary phase for detecting the degree of alkalinity/ion concentration is to be performed. The control unit then executes said preliminary phase up to its completion. As previously mentioned, the flow of water charged for the purposes of execution of the preliminary phase passes through a specific compartment of the dispenser 6, i.e., the compartment 6a in the example considered herein. Given that the user wishes to carry out just rinsing of the laundry, detergent has not been introduced into said compartment (the user will possibly have introduced a softening agent into the compartment 6c).

Since residue of detergent is in any case present in pre-treated laundry, the measured value of alkalinity/ion concentration will be higher than (or else higher than or equal to, according to the chosen approach) the aforesaid stored threshold value. Upon occurrence of said condition, the control unit 14 will issue a command for execution of the program corresponding to the rinsing cycle, which is executed up to its completion, in a way in itself known.

There will now be supposed the case where the user, instead of subjecting pre-treated garments to rinsing, wishes to cany out a washing operation using the fast cycle. The operations for the purpose are exactly the same as the ones previously referred to, with the difference that in this case the user will also have to introduce a dose of detergent into the relevant compartment of the dispenser 6 for the cycle considered, namely, the compartment 6b.

Also in this case, the water charged from the water supply 9 will pass through the compartment 6a, which does not contain detergent, and will reach the tub 3 substantially pure. The measured value of alkalinity/ion concentration will now be lower than (or else lower than or equal to, according to the chosen approach) the aforesaid stored threshold value. Upon verification of said condition, the control unit 14 will issue a command for execution of the program corresponding to the fast cycle, which is executed up to its completion in a way in itself known. From what has been described above, it emerges how the machine 1 is prearranged for recognizing, autonomously, which treatment cycle the user wants between the two cycles associated to the specific programming means selected. In the user interface of the machine there can thus be eliminated a specific programming key (or a position of a selector, or an icon on a touch-screen display), i.e., the one traditionally provided for selection of the rinsing cycle.

The invention thus enables simplification of the user interface of the machine and reduction of the overall dimensions thereof, or else, given the same overall dimensions as appliances of a known type, makes it possible to have available keys, selectors or displays of larger dimensions for the benefit of the user.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein purely by way of example, without thereby departing from the scope of the present invention as defined in the annexed claims.

As already mentioned, the manual programming means of the machine according to the invention may be of the type with keys or push-buttons, or else of the type with rotary selector or linear selector with a number of positions, or else of the touch-screen-display type.

The detection means used in the practical implementation of the invention could be of any known type suitable for detection of the presence of a washing agent in the water even different from the one described previously. For this purpose it is pointed out, for example, that turbidity sensors, of a type in itself already known and used on some models of washing machine or dish-washer available on the market, can be used for the purposes of implementation of the invention in so far as they are perfectly able to detect the presence of a washing agent in the water.

The machine according to the invention can possibly be of the type equipped with a dispenser of washing agents with long autonomy of operation, i.e., of the type that is able to withhold, in one or more purposely provided containers or tanks, total amounts of washing agents such as to be used for a plurality of washing treatments, as well as to dispense dosed amounts of said agents in the course of each treatment cycle.

The present invention finds its best application on a laundry washing machine for domestic use; however, it is applicable to any washing machine. In the case of a dish-washer for domestic use, for example, the machine can be designed such that it is able to carry out a plurality of treatment cycles, amongst which: a) a given cycle of washing of the dishes; and b) a cycle of rinsing and/or lustring of the dishes, or else a cycle of soaking of the dishes.

As in the first embodiment described, the two aforesaid cycles can be selected manually by the user by means of one and the same selection device, for example, by exerting pressure on a purposely provided push-button. The dishwasher is electronically controlled and comprises means for detecting a characteristic of the liquid charged in the tub, for example, a conductivity sensor or an alkalinity sensor or a turbidity sensor, as mentioned previously for the case of a laundry washing machine. According to the detection of said characteristic of the liquid, the electronic control system discriminates whether to set in execution the first or else the second of the aforesaid cycles of the machine, according to an approach similar to what has been described previously. In this implementation, the preliminary phase for detecting the aforesaid characteristic will include - instead of the step of rotation of the drum envisaged in the case of a laundry washing machine - a step of activation of the washing or recirculation pump of the dish-washer, in order to spray, using at least one conventional rotary sprinkler, the water charged in the tub onto the dishes, the latter being contained in at least one conventional dish rack.

In the examples of embodiment previously described, the program of the rinsing cycle is associated to a specific selection means (the key 13e, in the example of the laundry washer). In an alternative embodiment, said program could be associated also to each of the other programming keys, together with the respective program/cycle. In this case, the control system will thus be pre-arranged for carrying out, at each use of the machine, the aforesaid preliminary detection phase, with subsequent automatic starting of one between the two possible treatment cycles associated to the selection made by the user.

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Claims

"k "k rkCLAIMS

1. A washing machine, particularly a laundry washing machine, comprising at least a wash tub (3), charging means (7, 8) for supplying a liquid to said tub (3), drain means (10, 12) for evacuating the liquid from said tub (3), a device for dispensing washing agents (6), and a control system (13, 14, 17), wherein the control system (13, 14, 17) comprises at least:

- a control unit (14), configured for managing a plurality of treatment cycles that can be carried out by the machine (1);

- memory means (16), in which management programs of said treatment cycles are stored;

- programming means (13), for making a manual selection among a plurality of possible selections (13b-13e), there being associated to each selection that can be made via the programming means (13) at least one respective management program; and

- detecting means (17) for detecting a characteristic of the liquid charged in said tub (3), characterized in that the control system (13, 14, 17) is arranged such that associated to a selection (13b) that can be made via the programming means (13) are two different management programs, corresponding to two different treatment cycles, and the control unit (14) is configured for carrying out one or the other of said two management programs depending on a value of said characteristic obtained via said detection means (17) following upon a first charging of liquid into said tub (3).

2. The machine according to Claim 1, wherein said first charging belongs to a preliminary phase for detecting said characteristic and the control unit (14) is configured for controlling execution of said preliminary phase in the case where said selection (13b) has been made.

3. The machine according to Claim 2, wherein in said memory means (16) a threshold value of said characteristic is contained and the control unit (14) is configured for:

- detecting, in the course of said preliminary phase and via said detection means (17), the value of said characteristic;

- carrying out a comparison between the detected value and the threshold value; and

- starting one or the other of said two management programs according to the result of said comparison.

4. The machine according to Claim 3, wherein said preliminary phase comprises a final draining of the liquid from said tub (3) and the control unit (14) is configured for controlling said draining after execution of said comparison and before start of one or the other of said two management programs.

5. The machine according to Claim 4, wherein the machine is a laundry washing machine, comprising a drum (4) for the laundry, which is mounted in said tub (3) and can be driven in rotation via motor means (5), and wherein said preliminary phase comprises a rotation of said drum (4) and the control unit (14) is configured for controlling said rotation before execution of said comparison.

6. The machine according to Claim 5, wherein the speed of said drum (4) during said step of rotation is higher than 70 r.p.m., preferably comprised between 80 and 100 r.p.m.

7. The machine according to Claim 6, wherein said speed is a speed such as to enable satellization of the laundry load in said drum (4).

8. The machine according to Claim 3, wherein said characteristic is representative of the presence of a washing agent in the liquid charged into said tub (3).

9. The machine according to Claim 8, wherein said characteristic is the alkalinity of the liquid or else the ion concentration of the liquid.

10. The machine according to at least one of the preceding claims, wherein said detection means comprise means for measuring the resistivity or else the conductivity of the liquid.

11. The machine according to at least one of the preceding claims, wherein said detection means comprise a sensor for detecting turbidity and/or a sensor for detecting hardness of the liquid.

12. The machine according to Claim 10, wherein said measuring means comprises:

- at least two electrodes (A, B) provided in the charging circuit of a capacitor (C) and provided for being in contact with the liquid charged in said tub

(3);

- means (Q) for discharging said capacitor (C);

- means (E) for causing a flow of current between said electrodes (A, B) through the liquid;

- means (15) for measuring the time necessary for achieving charging of said capacitor (C) via said flow of current; and

- means (15, 16) for calculating indirectly, as a function of the time of charging of said capacitor (C), the value of resistivity or conductivity of the liquid and deriving therefrom the value of said characteristic.

13. The machine according to Claim 1, wherein to one of said two management programs there corresponds a rinsing cycle.

14. The machine according to Claims 5 and 13, wherein said rinsing cycle comprises one or more phases, each phase providing for an initial charging of liquid into said tub (3), a rotation of the drum (4), and a final draining of the liquid from said tub (3).

15. The machine according to Claim 13, wherein to the other of said two management programs there corresponds a washing cycle, which comprises one or more washing phases with delivery of a washing agent.

16. The machine according to Claim 15, wherein said dispensing device is of the type with long autonomy of operation and said other management program includes information for controlling said dispensing device.

17. The machine according to Claim 4, wherein the machine is a machine for washing dishes, comprising at least one dish rack (4) in said tub (3), a washing or recirculation pump and at least one sprinkler member supplied via said pump, and wherein said preliminary phase comprises an activation of said pump and the control unit (14) is configured for controlling said activation before execution of said comparison.