EP3077582A1

EP3077582A1 - Laundry treatment apparatus having a laundry water content sensor

Info

Publication number: EP3077582A1
Application number: EP13799611.2A
Authority: EP
Inventors: Francesco Cavarretta; Federico DEL MASCHIO; Elena Pesavento
Original assignee: Electrolux Appliances AB
Current assignee: Electrolux Appliances AB
Priority date: 2013-12-06
Filing date: 2013-12-06
Publication date: 2016-10-12
Also published as: WO2015082018A1

Abstract

The invention relates to a laundry treatment apparatus (2), in particular laundry dryer, washing machine or washer dryer, the laundry treatment apparatus comprising: a casing (3), a laundry storing compartment (17) arranged within the casing (3) for receiving laundry to be treated, a contactless laundry water content sensor (200) adapted to detect the amount of water contained in the laundry stored in the storing compartment (17), and a control unit for controlling the operation of the laundry treatment apparatus (2) and adapted to receive a signal from the laundry water content sensor (200). According to the invention, the control unit is either adapted to select or adjust one or more of the following parameters in dependency of the laundry water content sensor signal: estimated time to cycle end, drying air flow rate, drum rotation speed (tumbling or spinning), heat pump compressor operation parameters (speed, temporal profile), heating power, and/or self- cleaning operation. Preferably the control unit is adapted to receive a signal from a load detector (220), and wherein the control unit is adapted to process the signals from the load detector (220) and the laundry water content sensor (200) for determining a secondary parameter, which is depending on the load detector signal and the water content sensor signal and which is used by the control unit for controlling a drying and/or spinning operation of the laundry treatment apparatus (2).

Description

5 LAUNDRY TREATMENT APPARATUS

HAVING A LAUNDRY WATER CONTENT SENSOR

o The invention relates to a laundry treatment apparatus, in particular a laundry dryer, having a laundry storing compartment and a laundry water content sensor for detecting the amount of water contained in the laundry stored in the laundry storing compartment.

GB 1 232 839 B discloses control circuits for a fabric drying machine using the reflection 5 pattern of HF electromagnetic waves, in particular microwave radiation, to prevent

termination of the drying machine when the moisture content of the fabrics is above a predetermined threshold.

DE 100 34 585 Al teaches a washing machine having a radar sensor, particularly a o Doppler radar sensor for arranged for detecting operation status parameters of the machine.

The sensor is arranged for observing the interior of the laundry drum and for detecting signals corresponding to e.g. vibrations of the drum or the machine, rotation speed of the drum, the amount of laundry loaded, or the water level in the drum. The sensor may also provide indirect information about the motor, pumps, mountings, shock absorbers and/or 5 laundry or machine temperature. Furthermore, the sensor is proposed for sensing the grade of impurity of the water in the drum.

DE 101 63 199 A 1 teaches a laundry treatment apparatus with a sensor for detecting the humidity of laundry in the laundry drum, wherein the sensor comprises a microwave o resonator and a probe head for feeding an electromagnetic stray field into the drum. A

measurement circuitry is arranged for determining characteristic parameters of the resonator which are dependent on the dielectric properties of surrounding material, i.e. laundry in the drum. From the measured parameters the humidity of the laundry can be determined.

5

WO 2013/088830 Al discloses a laundry dryer for drying laundry stored in a rotating drum, wherein the dryer is equipped with an electromagnetic wave generation unit, an electromagnetic wave detection unit, and a computation unit. The electromagnetic wave generation unit emits electromagnetic waves at frequencies in the range of 100 GHz - 120 THz into the interior of the drum. The electromagnetic wave detection unit detects electromagnetic waves emitted by the generation unit that have passed through the drum. 5 The computation unit determines the laundry drying state based on a signal output from the detection unit.

It is an object of the invention to provide a laundry treatment apparatus comprising a laundry water content sensor adapted to detect the amount of water contained in the o laundry to be treated, in which the laundry treatment is further improved.

The invention is defined in claims 1 and 3, respectively. Particular embodiments of the invention are set out in the dependent claims. 5 According to the invention a laundry treatment apparatus comprises a casing, a laundry storing compartment within said casing for receiving the laundry to be treated, a contactless water content sensor, and a control unit. In particular, the laundry treatment apparatus may be a laundry dryer, a washing machine, a washer dryer, or the like. The contactless water content sensor is adapted to detect the amount of water contained in the o laundry stored in the storing compartment. The contactless water content sensor may

comprise at least one high frequency electromagnetic wave emitter and/or at least one high frequency electromagnetic wave receiver. Other types of contactless water content sensors are applicable in the embodiments, as described below. The control unit is adapted to receive a signal from the laundry water content sensor and serves for controlling the 5 operation of the laundry treatment apparatus. The control unit is furthermore adapted to select or adjust one or more of the following parameters in dependency of the laundry water content sensor signal: estimated time to cycle end, drying air flow rate, cooling air flow, drum rotation speed during tumbling, parameters of heat pump compressor operation, heating power, and/or parameters of a self-cleaning operation for removing fluff from a o drying air fluff filter of the apparatus by flushing the filter with a liquid, preferably water and highly preferably water condensed during the laundry drying process. In an embodiment, the laundry storing compartment preferably is or comprises a laundry drum, preferably a front loading drum 5 Here and in the following the term "cycle" in the context of laundry treatment operation is used to denote a laundry treatment program or program sub-routine of the laundry treatment apparatus, such as tumbling, spinning, drying, steaming and/or self-cleaning. In an embodiment, the control unit uses the signal received from the laundry water content sensor in order to select and/or adjust the estimated time to cycle end, i.e. the time until the current or a subsequent laundry treatment operation cycle will be finished. The obtained estimated time to cycle end can be used for controlling the machine operation, e.g. the 5 rotation speed and/or acceleration and/or deceleration of a laundry drum, a steam

generation rate and/or heating power provided for drying. Alternatively or in addition, the estimated time to cycle end may be used to provide information to the user, e.g. display the remaining time required for laundry treatment on a display unit. o Preferably, the signal received from the laundry water content sensor is additionally or alternatively used by the control unit for selecting and/or adjusting the flow rate of drying air that is guided through the laundry storing compartment, in particular during laundry drying operations. In particular, a fan or drying air blower may be provided for moving said drying air and for controlling its flow rate.

5

In an embodiment, the drying air is cooled and/or dehumidified in a heat exchanger by means of a cooling air stream (e.g. in a (cross-flow or counter-flow) air/air heat exchanger). In addition to or instead of adjusting the drying air flow, the control unit may be arranged for selecting and/or adjusting the cooling air flow in dependency of the o laundry water content. Preferably, here the 'cooling air stream' is a flow of cooling air drawn into the cabinet of the laundry treatment apparatus from outside and the cooling air having undergone heat exchange is exhausted to the outside of the apparatus cabinet. Alternatively or additionally the heat exchanger is a drying air / ambient air heat exchanger, for example of the cross flow type. Such cooling air is used for example in case 5 the laundry treatment apparatus is a condenser-type dryer or washer-dryer with a closed process loop and a condensate collector that collects the condensate condensed out of the drying air at the heat exchanger. In an alternative or additional embodiment the 'cooling air stream' is a flow of ambient (from outside cabinet) air flowing over the compressor and/or auxiliary heat exchanger used in the heat-pump system of a heat-pump dryer or washer- o dryer.

Furthermore, in addition or alternatively, the laundry water content sensor signal may serve for adjusting and/or selecting the rotation speed of a laundry drum, in particular during tumbling. In the related embodiments, said laundry drum is rotatable and may be part of 5 the laundry storing compartment, e.g. with the laundry storing compartment comprising a circumferential wall defined by said rotatable drum, a back wall, and/or a front wall opposite to the back wall with a front loading opening for loading laundry into the laundry storing compartment.

In an embodiment, the laundry water content sensor signal may serve in addition or alternatively for adjusting and/or selecting operation parameters of a heat pump

5 compressor. Such heat pump compressor is part of a heat pump system that may be

comprised by the laundry treatment apparatus and may serve for drying and heating a flow of drying air that is guided through the laundry storage compartment, e.g. during a laundry drying program. The heat pump compressor operation parameters to be selected and/or adjusted may include one or more of: the compressor speed; the temporal profile of the o compressor speed and/or the input power provided to the compressor. By selecting and/or adjusting such parameters it is possible to control, e.g., the air humidity or dehumidifying degree of the drying air, the temperature of the drying air, the amount of water extracted from the drying air, the total power and/or energy consumption of the laundry treatment apparatus.

5

According to an embodiment, the signal received from the laundry water content sensor is additionally or alternatively used by the control unit for selecting and/or adjusting the heating power used for drying laundry. In this way it is possible to control, e.g., the temperature of the drying air which the laundry to be dried is exposed to, the duration of o the drying process, the drying rate, the total power and/or energy consumption of the

laundry treatment apparatus.

Furthermore, in addition or alternatively, the laundry water content sensor signal may serve for selecting and/or adjusting parameters of self-cleaning operations carried out by the 5 laundry treatment apparatus. The self-cleaning operations are for removing fluff from a drying air fluff filter of the apparatus by flushing the filter with a liquid, preferably water and highly preferably water condensed during the laundry drying process.

In particular, the laundry water content sensor signal may be used to estimate of the laundry water content at the beginning of, e.g., a laundry drying cycle. This can provide a o value of the whole amount of water removed and/or to be removed from the laundry. The so-obtained knowledge about the total amount of water removed and/or to be removed can implicitly provide knowledge about the amount of water available for self-cleaning cycles, in particular when the condensation efficiency of the laundry treatment apparatus machine is known a priori, e.g. by design. The control unit can use this information to control self- 5 cleaning cycles carried out by the laundry treatment apparatus as will be explained below in more detail. In an embodiment, the laundry treatment apparatus further comprises a load detector adapted to detect the weight of laundry stored in the laundry storing compartment. The control unit is adapted to receive a signal from the load detector. It can determine a secondary parameter depending on the received load detector signal and water content 5 sensor signal. Said secondary parameter may be used by the control unit for controlling the operation and/or operation parameters of the laundry treatment apparatus, for example related to a drying and/or spinning operation or the like.

In an embodiment, said load detector may be or may comprise for example one or more of o the following: a weight sensor (e.g. connected to or integrated in the mounting of the drum); a sensor detecting oscillations/vibrations of the drum and/or machine; a sensor detecting the speed of drum rotation or its variations (in particular as a direct signal or in relation to an electrical and/or magnetic parameter of the motor driving the drum, like the supplied current, voltage and/or power and/or the magnetic flux detected by a magnet field 5 sensor); a logical component or piece of software integrated in or attached to the control unit for determining load indirectly (e.g. from the absolute value and/or average value and/or variations of the motor torque, the motor supply current, the motor current, the motor power consumption and/or the motor supply power) a signal obtained from manual user input; and/or a conductivity measurement system. Although it normally is used as a 0 humidity detector, the signal of a conductivity sensor (e.g. one placed at the inside of the drum or a front frame or back wall of the drum) may also be evaluated by the control unit to derive therefrom a measure for the laundry load in the laundry storing compartment (which is a drum in the preferred embodiment). 5 Preferably the control unit is adapted to receive the water content signal from the water content sensor and the load signal from the laundry load detector or sensor and to process or evaluate the signals for determining the humidity value of the laundry (moisture content or degree of the laundry) stored in the laundry storing compartment. So both signals are used to calculate or estimate a more reliable value for the relative moisture content of the o laundry. The 'relative' moisture or humidity content can be considered covering a range from 100% (where the laundry is wet close to dripping) and 0% where it has lost all humidity. In an embodiment thereof the control unit is further adapted to determine the humidity value of the laundry in dependency of the laundry type, and/or by retrieving the humidity value from a look-up table providing humidity values in dependency of the water 5 content and load signals.

In an embodiment, the control unit is furthermore adapted to select or adjust one or more of the following parameters in dependency of the laundry water content sensor signal: estimated time to cycle end, drying air flow rate, drum rotation speed during tumbling and/, parameters of heat pump compressor operation, heating power, and/or parameters of self-cleaning operation. In an embodiment, the laundry storing compartment preferably is or comprises a laundry drum, preferably a front loading drum

The signal(s) from the laundry water content sensor and/or the load detector can further be used in addition or alternatively for selecting and/or adjusting other parameters of the laundry treatment apparatus, such as a steam generation rate, steaming time intervals, duration of warm-up, water flow rate to the steamer, creating user signals e.g. related to the water level in water reservoir.

As will be understood by a person skilled in the art, the signal(s) from the laundry water content sensor and/or the load detector may comprise analog and/or digital signal components and may be transmitted by a single signal line or a plurality of signal lines, in particular a signal bus, more in particular embodied according to a standardized interface such as I2C, SPI or CAN.

Preferably, said secondary parameter determined by the control unit may comprise one or more of the following: the humidity of the laundry; the absolute total water amount within the laundry storing compartment; the dry weight of the laundry; the distribution of the laundry in the laundry storing compartment; the distribution of water within the laundry storing compartment; and/or the type of laundry. Preferably, said secondary parameter determined by the control unit comprises, is related to, or indicates the humidity of the laundry to be treated. In particular, the secondary parameter may indicate the humidity of the laundry in the laundry storing compartment, e.g., quantified as weight or mass of water per weight or mass of laundry. In particular, determining the secondary parameter by the control unit may comprise deriving the weight or mass of laundry water content from the laundry water content sensor signal, deriving the weight or mass of laundry from the load sensor signal, and/or dividing the derived weight or mass of laundry water content by the derived weight or mass of laundry (or vice versa). Deriving the weight or mass of laundry water content and/or deriving the weight or mass of laundry may also comprise derivation of intermediate signals from the respective sensor signals or from combinations of different sensor signals.

More preferably, in addition or alternatively, the secondary parameter determined by the control unit comprises, is related to, or indicates the absolute total water amount within the laundry storing compartment. The water content sensor may, e.g., be limited to measuring the laundry water content within a certain constricted volume of the laundry storing compartment or contained in a constricted portion of the laundry. This may be due to "blind zones" of the sensor (see below) or because of a limited depth of penetration achievable by the applied measurement method. The control unit may then derive the absolute total water amount within the laundry storing compartment by means of correcting the laundry water content sensor signal using the load detector signal. In an embodiment, the secondary parameter determined by the control unit may further or alternatively comprise the dry weight of the laundry, e.g. derived from the total weight of the wet laundry and the total amount of water in the laundry storing compartment. As explained above, these quantities may be obtained directly from respective sensor signals or indirectly using intermediate signals derived from individual or combined sensor signals. Knowing the total weight of the wet laundry as well as the total amount of water in the laundry storing compartment it is possible to derive the dry laundry weight, e.g., by subtracting the weight of the total amount of water from the total weight of the wet laundry. In another embodiment, the secondary parameter determined by the control unit may further or alternatively comprise the type of laundry in the laundry storing compartment, which is beneficial, e.g., as it allows to adapt parameters of the laundry treatment such as a maximum water, steam and/or drying air temperature to the needs of the laundry being treated. In this context, the type of laundry may be defined, e.g. by its specific water absorbance, specific weight, or similar parameters. Determining the type of laundry may preferably include determining the dry laundry weight, comparing the dry laundry weight to the wet laundry weight, determining the rate of water removal from the laundry, determining a specific water absorbance of the laundry, and/or the like. Preferably, the secondary parameter determined by the control unit may further or alternatively comprise the distribution of the laundry and or the distribution of water within the laundry storing compartment. Having signals indicating one or both of these distribution is especially beneficial for adjusting the drum speed and/or acceleration and/or deceleration so as to avoid excessive vibrations of the machine and/or in order to create a more uniform distribution while spinning up the drum. Furthermore, the drum may be turned faster during a laundry drying cycle when the water content distribution is detected to be non-uniform while the drum rotation may be reduced or even stopped, when the water content is detected to be uniform, which can be an advantage for achieving a low power consumption of the laundry treatment apparatus.

In a further embodiment, deriving the secondary parameter by the control unit may also 5 comprise obtaining a user input, in particular a user input indicating the type of laundry loaded into the laundry storing compartment.

In an embodiment, the control unit is adapted to determine a laundry load value using the signal from the load detector and to adjust the so-obtained laundry load value by means of o the signal obtained from the laundry water content signal. This is particularly beneficial, if the signal from the load detector alone does not or not under all circumstances provide a sufficiently accurate value of the weight of the laundry in the laundry storing compartment. For example, the load detector may be embodied in the form of a conductivity

measurement system. As will be explained below in more detail, such a system can be used5 to estimate the amount of laundry in a rotating laundry drum by evaluating, for example, the variations and/or noise in the measured conductance between two detector electrodes. As the measured conductance values depend on the amount of laundry in the drum as well as on the humidity of the laundry, a more accurate value of the laundry weight can be derived by correcting the load detector signal using the laundry water content sensor o signal.

In a further embodiment, the control unit is adapted to determine a laundry water content value using the laundry water content sensor signal and to adjust the so-obtained laundry water content value using the load detector signal. This is especially beneficial, if the 5 signal from the water content detector alone does not or not under all circumstances

provide a sufficiently accurate value of the laundry water content. For example, the accuracy of the water content sensor may, e.g., be limited due to "blind zones" or because of a limited measurement penetration depth as mentioned above. The control unit may then obtain a more accurate value of the laundry water content by correcting the laundry water o content sensor signal using load detector signal.

Preferably, the laundry storing compartment is a rotatable drum driven by a drum motor and the load detector is a drum motor current, voltage, power and/or torque detector. When the laundry drum is slowly rotating, the laundry inside the drum creates a torque at the 5 drum motor that depends on the type of laundry, the weight of the laundry and the laundry distribution, because gravity keeps pushing the laundry towards the lower regions of the drum while the rotation of the drum keeps moving the laundry or portions thereof upwards at the drum mantle. Portions of the laundry reaching a certain height along the drum mantle fall back to near the bottom of the drum and then are raised up again. Furthermore the torque needed to accelerate the drum (e.g. when starting a spinning operation) also depends on the weight of the laundry and possibly the type and distribution of the laundry.

5 Measurements of the torque at the motor thus allow to estimate the weight of the laundry in the drum and thus a load detector can be implemented in the form of a motor torque detector or comprising a motor torque detector. Preferably, a motor torque detector can be implemented in the inverter control electronics which is providing power to the motor, because the power to be provided to the motor is related to the torque created by the motor. o Instead of a motor torque detector a motor current, motor voltage or motor power detector may be provided.

The repeated raising and falling back of the laundry in a slowly moving drum as explained above also creates a pattern of temporal variations of the torque. The statistical properties5 of these variations, such as amplitude and frequency spectrum in dependence of the drum speed also provide information about the weight of the laundry, its type, distribution, and water content. In an embodiment, generating the load detector signal by the load detector and/or generating the laundry water content signal by the laundry water content sensor therefore comprises detecting temporal variations of the motor torque. Alternatively or in o addition, the control unit receives a separate signal containing information on variations of the motor torque and uses this signal for deriving or adjusting the load detector signal and/or the laundry water content signal.

In an embodiment, the laundry water content sensor may not only generate a laundry water 5 content signal but may additionally provide useful data on the weight of the laundry in the laundry storing compartment. For example, as will be explained below in more detail, in an embodiment, a laundry water content sensor may be designed to emit high frequency electromagnetic waves into the laundry storing compartment and detect the signals arising from portions of the waves that are transmitted through and/or reflected by the laundry. In 0 a similar way as the movement of the laundry in a slowly rotating drum creates temporal variations of the motor torque (see above), it will create characteristic temporal variations in the detected high frequency electromagnetic wave signals depending on the weight, type, and/or distribution of the laundry in the drum. Such signals can thus be useful for determining the weight of the laundry in the laundry drum.

Similarly, preferably the load detector may not only generate a signal indicating the weight of the laundry in the laundry storing compartment but may additionally contain information on the laundry water content, as mentioned above in the examples of the conductivity measurement load detector and the motor voltage, current or power detector.

According to the above, an embodiment of the load detector detects the weight of laundry stored in the laundry storing compartment by evaluating at least one signal from the laundry water content sensor. Furthermore, in an embodiment the water content sensor may detect the laundry water content by evaluating at least one signal from the load detector. Preferably, the same sensor or plurality can be used for generating both a load sensor signal and a water content sensor signal.

In an embodiment, the contactless laundry water content sensor comprises at least one high frequency (HF) electromagnetic wave emitter and/or at least one high frequency (HF) electromagnetic wave receiver. The high frequency electromagnetic wave emitter emits high frequency electromagnetic waves into the laundry storing compartment. A portion of the emitted waves is absorbed by the humid laundry or leaves the laundry treatment apparatus and does not reach the receiver. Another portion of the emitted waves is transmitted through the laundry and forms a transmitted electromagnetic signal that reaches the receiver. Yet another portion of the emitted waves is reflected by the humid laundry and/or parts of the laundry treatment apparatus and forms a reflected signal also reaching the receiver. Note that in the present context, the term "reflection" is meant to comprise not only reflection in its narrow sense but also refraction as well as absorption with subsequent re-emission with unchanged and/or changed frequencies.

In an embodiment, the or a high frequency electromagnetic wave emitter and the or a high frequency electromagnetic wave receiver forming the contactless laundry water content sensor are separate components mounted at opposite to each other with respect to the laundry storing compartment, so that electromagnetic waves emitted by the emitter can pass through the laundry storing compartment towards the receiver. Generally herein the 'emitter' can also be denoted or understood as being a 'transmitter' and/or the 'receiver' can be understood as sensor detecting a or the respective signal. In an alternatively or additionally embodiment one or more electromagnetic wave emitters are provided only (without providing an electromagnetic wave receiver) and the signal loss is detected by detecting a damping value (signal damping or attenuation or transmission loss) of the signal emitted from the one or more emitters. In this case e.g. the absorption of the signal (signal damping) depends on the amount of water in the laundry storing compartment. Nonetheless, for simplicity herein, also the emitter-only or transmitter-only arrangement where the HF signal is emitted and received by the same element is denoted as 'HF electromagnetic wave emitter and HF electromagnetic wave receiver'.

In another embodiment, the high frequency emitter and the high frequency receiver are integrated into a common housing, mounted on a common substrate, and/or use a single 5 antenna for signal emission and reception. In such an embodiment both transmitter and receiver are preferably located on the same side of the laundry storing compartment and the receiver is preferably be adapted to receive electromagnetic signals that are reflected by the laundry. o Preferably, the frequency or frequencies of the electromagnetic radiation emitted by the emitter and/or the frequency or frequencies which the receiver is tuned to are adjusted so that the radiation interacts preferably with the water inside the laundry instead of other material such as, e.g., textiles fibers. In this way, the different portions of absorbed, transmitted and/or reflected electromagnetic waves significantly depend on the laundry5 water content, so that the strength and other characteristics (e.g. temporal variations, frequency spectrum, phase shifts and/or time delays) of the electromagnetic signals reaching the high frequency electromagnetic wave receiver strongly depend on the laundry water content. As a consequence, the laundry water content can be estimated from the signal(s) generated in the HF electromagnetic wave receiver and/or by comparing those o signals with the characteristics of the electromagnetic waves emitted by the HF

electromagnetic wave emitter.

Preferably, the high frequency or the high frequencies used by the laundry water content sensor is/are in the range of 900 to 930 MHz and/or in the range of 2.4 - 2.5 GHz, and/or in 5 the range of 5.7 - 5.9 GHz. More preferably, the high frequency or the high frequencies used by the laundry water content sensor 200 is/are in the range of 902 to 928 MHz and/or in the range of 2.400 - 2.483 GHz, and/or in the range of 5.725 - 5.875 GHz.

o Preferably, the laundry water content sensor is adapted to detect the signal absorption by the laundry, the signal reflection by the laundry, or the signal absorption and signal reflection by the laundry. Preferably, the laundry water content sensor is adapted to detect signal absorption and/or reflection by measuring the transmitted and/or absorbed and/or reflected signal intensities. More preferably, the laundry water content sensor is adapted to 5 detect further signal interactions with and/or signal modifications by the laundry, in

particular regarding phase relationships, phase shifts, and/or time delays. Preferably, at least one high frequency electromagnetic wave emitter and/or at least one high frequency electromagnetic wave receiver comprises a planar antenna, in particular a patch antenna. A patch antenna (which may be a microstrip antenna) is a thin antenna, preferably comprising a rectangular layer (patch) of metal mounted above a larger

5 rectangular sheet of metal forming the ground plane. Preferably, the components are

surrounded by a plastic casing for protection against environmental influences such as moisture or mechanical stress. Preferably at least one of the linear dimensions of the rectangular metal layers is in the order of one half of the wave length of the emitted or received electromagnetic waves. A patch antenna can be built, for example, on a dielectric o substrate, using the same or similar materials and techniques as are well known from the production of printed circuit boards.

Planar antennas are very common in sensing applications. Advantages of patch antennas include their compact size, low cost, reliability, robustness, large-scale availability,5 reproducibility, and simple integration into larger systems. They can be tuned to a wide range of frequencies and, in particular, they are easy to integrate into array structures combining microstrip antennas with other electronic functions. Therefore patch antennas are particularly well suited as sensor components for use in a laundry treatment apparatus. 0 In an embodiment, the control unit of the laundry treatment apparatus is adapted to execute a calibration cycle for calibrating the laundry water content sensor and/or the load detector when the amount of water inside the laundry storing compartment is known. Such calibration is useful for minimizing deviations of the detected laundry water content and/or the detected load from the true values of water content and/or laundry weight in the 5 laundry storing compartment. Such deviations may occur for example with increasing life time and/or operation hours of the laundry treatment apparatus, because the physical properties of the sensor components can change over time, e.g. as a result of ageing effects. In particular, said calibration cycle may comprise recording and/or processing of the signal(s) from the laundry water content sensor and/or the load detector at one or several o instances in time. Preferably, said calibration cycle is executed when no laundry is stored in the laundry storing compartment. In order to make sure that the laundry storing compartment is empty when executing the calibration cycle, one or more of the following conditions may be checked in the embodiments:

- a laundry detector preferably mounted at a lower part of the drum, indicates that no 5 load is in the laundry storing compartment;

- the load detector signal is (apart from very small deviations) consistent with the signal expected for an empty laundry storing compartment; - the water content sensor signal is (apart from very small deviations) consistent with the signal expected for an empty laundry storing compartment;

- a certain amount of time has expired after finishing a drying and/or spinning cycle, so that the user is expected to have removed the dry laundry; and/or

5 - an opening and/or closing of the loading door has been detected, in particular after finishing a drying and/or spinning cycle, so that the user is expected to have removed the dry laundry.

In an embodiment, the laundry water content sensor and/or the load detector (in the o following commonly denoted as "sensors") or at least one of the sensor components is/are arranged in a lower region of the laundry storing compartment. Such an arrangement is particularly beneficial if the accuracy of the sensor measurements depends on the distance between the laundry and the respective sensor or one of its components because gravity will push the laundry towards the lower region of the laundry storing compartment and 5 thus close to any sensor mounted near to that region. Furthermore, such an arrangement provides for an increased probability that a significant amount of the laundry is within the active area or active volume of the respective sensor. Here the terms "active area" and "active volume" are used to denote the area or volume of the laundry storing compartment within which laundry water content or laundry weight can be most effectively sensed by o the respective sensor.

Preferably, the laundry storing compartment is rotatable drum and the laundry water content sensor and/or the load detector or at least one of the sensor components is/are arranged at a position in the lower region of the drum and shifted along the main rotation 5 direction of the drum mantle. This arrangement increases the probability that a significant amount of the laundry is within the active area or active volume of the respective sensor, because as described above, when the drum is slowly rotating, then the pieces of laundry will be raised along the drum mantle following the drum rotation direction before falling back towards the bottom of the drum. Furthermore, when the drum is spinning at a higher 0 speed, then the laundry will be compressed towards the laundry mantle, so that it can be beneficial to place the sensors or sensor components at positions sufficiently close to the mantle.

In an embodiment, the laundry water content sensor and/or the load detector are positioned 5 at or close to the drum mantle.

Preferably, at least parts of the laundry storing compartment wall or wall sections are made of material that is transparent for passing the high frequency electromagnetic waves used by the laundry water content sensor. In particular, the laundry drum, a lateral wall of the laundry drum, and or a lateral wall of the laundry storing compartment (or appropriate portions thereof) could be made of plastics or plastic-polymeric material such as PTFE (e.g. Teflon), PE, PP, and/or polyamides. In cases where the laundry storing compartment 5 is formed as a laundry drum, preferably the drum mantle or portions of the drum mantle and/or the drum rear wall and/or a back wall of the laundry dryer are made of appropriate material that allows the HF electromagnetic waves to pass through, i.e. that is transparent for the selected HF electromagnetic frequency or frequencies. 0 In a preferred embodiment, the water content sensor and/or the load sensor are placed outside the laundry storing compartment. In this way, the sensor components can be well protected against humidity, pollution by fluff, or mechanical stress created by the laundry. As an advantage, the sensor may reach an increased life time and/or can be designed to be more cost efficient.

5

Preferably at least one component of the laundry water content sensor is placed outside of the laundry storing compartment. More preferably all components of the laundry water content sensor are placed outside of the laundry storing compartment. o Preferably at least one component of the load detector is placed outside of the laundry storing compartment. More preferably all components of the load detector are placed outside of the laundry storing compartment. As an additional advantage, mounting the laundry water content sensor and/or the load detector outside the laundry storing compartment may avoid or reduce "blind zones" of the detectors, as will be explained 5 below in more detail.

In an embodiment, selecting or adjusting the drying air flow rate by the control unit in dependency of the laundry water content sensor signal comprises selecting one of at least two different predetermined target levels of the drying air flow rate depending on the o laundry water content. Alternatively or in addition, the control unit may adjust the target drying air flow rate smoothly within a predefined range of target flow rates in dependency of the determined laundry water content. Preferably, a drying air blower is arranged such that the created drying air flow rate and/or the created average drying air flow rate is at or close to the target flow rate selected and/or adjusted by the control unit. Alternatively or in 5 addition, the control unit may adjust and/or select a target rotation speed of the drying air blower and/or adjust and/or select the electrical power provided to the drying air blower in dependency of the determined laundry water content. In an embodiment, the drying air is cooled and/or dehumidified in a heat exchanger by exchanging heat with a cooling air stream (e.g. in a condensate-type dryer or washer- dryer). Alternatively or additionally the cooling air stream is used to cool a component of a heat-pump system by exchanging heat with the cooling air stream. A component of the heat pump system cooled in this way is not in direct heat-exchanging contact with the process air and is e.g. a compressor or an auxiliary heat exchanger of a heat-pump system dryer or washer-dryer - reference is made to the above section relating to the 'cooling air stream'. The cooling air flow may be selected and/or adjusted in dependency of the laundry water content, e.g. as follows: At the beginning of a drying cycle, when the laundry water content is still high, only a relatively low cooling air flow rate is created, because the laundry needs to be heated up to the drying temperature first, so that any heat energy taken away by the cooling air flow during that phase is wasted and leads to an increase of the time needed for laundry drying. However, when the designated operating temperature is reached and the laundry water content decreases significantly, the cooling air flow can be increased in order to increase the rate of water removed from the drying air A and thus achieve efficient drying. In this way, the described process of selecting and/or adjusting the cooling air flow helps to reduce both the time needed for a drying cycle and the overall energy consumption of the laundry treatment apparatus.

Preferably, selecting or adjusting the cooling air flow rate by the control unit in dependency of the laundry water content sensor signal comprises selecting one of at least two different predetermined target levels of the cooling air flow rate depending on the laundry water content. Alternatively or in addition, the control unit may adjust the target cooling air flow rate smoothly within a predefined range of target flow rates in dependency of the determined laundry water content. Preferably, a cooling air blower is arranged such that the created cooling air flow rate and/or the created average cooling air flow rate is at or close to the target flow rate selected and/or adjusted by the control unit. Alternatively or in addition, the control unit may adjust and/or select a target rotation speed of the cooling air blower and/or adjust and/or select the electrical power provided to the cooling air blower in dependency of the determined laundry water content.

In a further embodiment, a drying air flow is created by blowing external air (i.e. air from the outside of the apparatus cabinet) through the laundry treatment chamber. In an embodiment such laundry drying is made in the apparatus being a vented air dryer.

External air venting may be performed permanently or temporally, e.g. in a mixed vented/closed loop-type dryer. Preferably, the drying air flow rate is adjusted in dependency of the laundry water content, whereby selecting or adjusting the drying air flow can be achieved in the same way as described above for the cooling air flow.

In an embodiment, the laundry storing compartment is or comprises a rotatable laundry 5 drum, and the drum rotation speed is selected and/or adjusted in dependency of the laundry water content. Preferably, selecting or adjusting the drum speed by the control unit in dependency of the laundry water content sensor signal comprises selecting one of at least two different predetermined target levels of the drum speed depending on the laundry water content. Alternatively or in addition, the control unit may adjust the target drum o speed smoothly within a predefined range of target flow rates in dependency of the

determined laundry water content. Preferably, the drum motor is arranged such that the resulting drum speed and/or average drum speed is at or close to the target speed selected and/or adjusted by the control unit. Alternatively or in addition, the control unit may adjust and/or select the electrical power provided to the drum motor in dependency of the 5 determined laundry water content.

In a further embodiment the laundry treatment apparatus further comprises a steam generation unit for generating steam for laundry steam treatment which is controlled by the control unit, and the control unit is adapted to select or adjust one or more of the following o parameters in dependency of the laundry water content sensor signal and/or or the load detector signal: the flow rate of the steam provided for laundry treatment; the temperature of the steam provided for laundry treatment; and/or one or more time intervals during which steam is provided for laundry treatment. 5 Preferably the control unit is adapted to implement the control by one or more of the

following: a) increasing the drum rotation speed when the detected laundry water content sensor signal falls below a third predetermined value or is in a first predetermined value range (compare embodiments shown in Fig. 15 (W3)), and b) decreasing the drum rotation speed when the detected laundry water content sensor signal falls below a fourth o predetermined value or is in a second predetermined value range (compare embodiments shown in Fig. 14 (W2); Fig. 15 (W4)).

In an embodiment the control unit is adapted to implement the control by: c) decreasing the heating power when the detected laundry water content sensor signal falls below a fifth 5 predetermined value (W5) or is in a fourth predetermined value range, and optionally d) further decreasing the heating power when the detected laundry water content sensor signal falls below a sixth predetermined value (W6, W7) or is in a fifth predetermined value range.

In an embodiment the control unit of the laundry treatment apparatus is adapted to implement the control by one or more of the following: d) increasing the drying air flow 5 rate and/or the drying air blower speed when the detected laundry water content sensor signal falls below a first predetermined value or is in a first predetermined value range (compare embodiments shown in Fig. 13 (Wl)); e) decreasing the drying air flow rate and/or the drying air blower speed when the detected laundry water content sensor signal falls below a second predetermined value or is in a second predetermined value range0 (compare embodiments shown in Fig. 14 (W2); Fig. 15 (W4)).

Preferably the control unit (51) is adapted to implement the control by one or more of the following: f) increasing the cooling air flow rate speed when the detected laundry water content sensor signal falls below a third predetermined value or is in a third predetermined5 value range (compare embodiments shown in Fig. 14 (W2); Fig. 15 (W4), g)

decreasing the heating power when the detected laundry water content sensor signal falls below a fourth predetermined value or is in a fourth predetermined value range (compare embodiment shown in Fig. 17 (W5)), h) further decreasing the heating power when the detected laundry water content sensor signal falls below a fifth predetermined o value or is in a fifth predetermined value range (compare embodiment shown in Fig. 17 (W6, W7)).

In an embodiment the control unit is adapted to implement the control by one or more of the following: i) decreasing the compressor speed of a heat-pump system of the apparatus 5 or the compressing power of the compressor when the detected laundry water content sensor signal falls below a seventh predetermined value or is in a seventh predetermined value range or exceeds a first temporal gradient (dWl/dt) of the water content sensor signal, j) increasing the compressor speed of a heat-pump system of the apparatus or the compressing power of the compressor when the detected laundry water content sensor o signal falls below an eighth predetermined value or is in an eighth predetermined value range or exceeds a second temporal gradient (dW4/dt) of the water content sensor signal, and k) further increasing/decreasing the compressor speed of a heat-pump system of the apparatus or the compressing power of the compressor when the detected laundry water content sensor signal falls below/rises above a ninth predetermined value or is in a ninth 5 predetermined value range or falls below/rises above a third temporal gradient (dW2/dt; dW5/dt; dW6/dt) of the water content sensor signal. Above water content dependencies and controls can be combined in an arbitrary manner and/or the first to sixth predetermined values can be different or partially the same values. Preferably the first predetermined value is higher than the second predetermined value (or first range above second range). Preferably the fourth predetermined value is higher than the fifth predetermined value (or fourth range above fifth range).

Reference is made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying figures, which show:

Fig. 1 a schematic view of a laundry treatment apparatus,

Fig. 2 a perspective view of a laundry treatment apparatus,

Fig. 3 a schematic sectional side view of a laundry treatment machine with a

conductivity-measurement system comprising two electrodes,

Fig. 4 a detailed sectional view of the conductivity-measurement system comprising two electrodes as shown in Fig. 3,

Fig. 5 a schematic sectional side view of a laundry treatment machine with a

contactless laundry water content sensor and a load sensor,

Fig. 6 a schematic view of the laundry storing compartment of an embodiment of a laundry treatment apparatus with a contactless laundry water content sensor,

Fig. 7 a schematic view of the laundry storing compartment of another embodiment of a laundry treatment apparatus with a contactless laundry water content sensor,

Fig. 8 a schematic view of an embodiment of a contactless laundry water content sensor,

Fig. 9 a schematic view of another embodiment of a contactless laundry water content sensor,

Fig. 10 a schematic view of a further embodiment of a contactless laundry water

content sensor, Fig. 11a a schematic view of the laundry storing compartment of a further embodiment of a laundry treatment apparatus with a contactless laundry water content sensor,

Fig. 1 lb a schematic view of the laundry storing compartment of yet another

embodiment of a laundry treatment apparatus with a contactless laundry water content sensor,

Fig. 12 a graph illustrating the functional or experimentally determined relation

between the parameters water content / drum load / humidity,

Fig. 13 a graph illustrating the adjustment of drying air flow rate in dependency of the laundry water content,

Fig. 14, a graph illustrating the adjustment of drum speed in dependency of the laundry water content,

Fig. 15 a graph illustrating the joint adjustment of drying air flow rate and drum speed in dependency of the laundry water content,

Fig. 16 a graph illustrating the adjustment of heat pump compressor speed in

dependency of the laundry drying rate, and

Fig. 17 a graph illustrating joint adjustment of drying air heating power in dependency of the laundry water content.

The figures are not drawn to scale and are provided for illustrative purposes.

Fig. 1 shows a schematically depicted laundry treatment apparatus 2 having a cabinet or casing 3 and indicated/housed therein some of the apparatus components. The laundry treatment apparatus 2 comprises a heat pump system 4, including a closed refrigerant loop 6 which comprises in the following order of refrigerant flow B: a first heat exchanger 10 acting as evaporator for evaporating the refrigerant and cooling drying air, a compressor 14, a second heat exchanger 12 acting as condenser for cooling the refrigerant and heating the drying air, and an expansion device 16 from where the refrigerant is returned to the first heat exchanger 10. Together with the refrigerant pipes connecting the components of the heat pump system 4 in series, the heat pump system 4 forms the refrigerant loop 6 through which the refrigerant is circulated by the compressor 14 as indicated by arrow B.

The drying air flow A within the laundry treatment apparatus 2 is guided through a laundry 5 storing compartment 17 of the laundry treatment apparatus 2, i.e. through a compartment for receiving articles to be treated, e.g. a rotatable drum 18. The articles to be treated are textiles, laundry 19, clothes, shoes or the like. The drying air flow is indicated by arrows A in Fig. 1 and is driven by a drying air blower 8. The drying air channel 20 guides the drying air flow A outside the drum 18 and includes different sections, including the section0 forming the battery channel 20a in which the first and second heat exchangers 10, 12 are arranged. The drying air exiting the second heat exchanger 12 flows into a rear channel 20b in which the drying air blower 8 is arranged. The air conveyed by blower 8 is guided upward in a rising channel 20c to the backside of the drum 18. The air exiting the drum 18 through the drum outlet (e.g. the loading opening of the drum 18) is filtered by a fluff filter5 22 arranged close to the drum outlet in or at the channel 20. The optional fluff filter 22 is arranged in a front channel 20d forming another section of channel 20 which is arranged behind and adjacent the front cover of the laundry treatment apparatus 2. The condensate formed at the first heat exchanger 10 is collected and guided to the condensate collector 30. o The condensate collector 30 is connected via a drain conduit 46, a drain pump 36 and a drawer pipe 50 to an extractable condensate drawer 40. I.e. the collected condensate can be pumped from the collector 30 to the drawer 40 which is arranged at an upper portion of the laundry treatment apparatus 2 from where it can be comfortably withdrawn and emptied by a user.

5

The laundry treatment apparatus 2 comprises a control unit 51 for controlling and monitoring the overall operation of the laundry treatment apparatus 2. For example and as shown in Fig. 1 , the control unit 51 receives a temperature signal from a temperature sensor 41 which is arranged at the outlet of the second heat exchanger 12 (condenser) or at o the outlet of the compressor and which is indicative of the refrigerant temperature at this position. According to Fig. 1, the control unit 51 also controls the drain pump 36.

Additionally, the control unit 51 is able to control other parts of the laundry treatment apparatus 2. 5 In the embodiments, the laundry treatment apparatus also comprises a nozzle unit 88, a steam generation unit 90 (in short 'steamer'), and a steamer tank 140 for storing liquid to be supplied to the steam generation unit 90. A pump unit (e.g. the drain pump 36) is arranged for pumping the liquid collected in the condensate collector 30 to the drain tank 40 and/or to the steamer tank 140 via the branching element 142. From the liquid stored in the steamer tank 140, steam for laundry treatment can be generated in the steam generation unit 90 and guided to the nozzle unit 88 by means of a steam conduit 106. The nozzle unit 5 serves for injecting the generated steam into the laundry storing compartment 17.

Preferably, the nozzle unit 88 is mounted at a rear wall of the laundry treatment apparatus 2. Preferably, the steam generation unit is an inline steam generator. More preferably, the flow rate of steam generated by the steam generation unit and injected into the laundry storing compartment as well as other parameters of steam generation (e.g. steam o temperature, steaming intervals and/or heating energy) are controlled by the control unit

51.

The rotatable drum 18 is driven by a motor 150 via a belt 156. In a preferred embodiment the motor 150 also drives blower 8 and/or is a variable speed motor which can be driven 5 with a speed that is set by the control unit 51. Motor 150 is powered by an electronic board 152 (e.g. by an inverter) which in turn is controlled by control unit 51 via signal line 154. The electronic board 152 preferably sends a signal to the control unit 51 via line 154 indicating the motor torque and/or the temperature of electronic board and/or other parameters of the board and the motor (see further details below).

0

Fig. 2 shows a front perspective view of a laundry treatment apparatus that uses a heat pump system 4. The outer appearance of the depicted dryer 2 is defined by the casing 3 comprising a top cover 56, a left cover or wall 58, a front cover 60 having a front door 55 and a front top panel 62. The front top panel 62 frames a drawer cover 64 of the

5 condensate drawer 40. The right portion of the front top panel 62 forms an input section 66 wherein here the elements (like indicators, a display, switches and so on) of the input section 66 are not shown in detail.

Fig. 3 illustrates a schematic sectional side view of a laundry treatment apparatus 2 with o two electrodes 82 and 84 forming an embodiment of a conductivity system that can be used for estimating the laundry humidity and/or the laundry load inside the laundry drum 18 (see below). The apparatus 2 comprises the laundry storing compartment 17 inside the laundry drum 18, the front door 55, the loading opening 54 of the drum 18, heat exchangers 10, 12, and a front frame 70. The electrodes 82 and 84 are attached at the rear 5 side of the front frame 70 and are arranged at a lower portion of a laundry loading front opening 54 of the laundry drum 18 and below the front door 55. The first electrode 82 is arranged above the second electrode 84. In this embodiment, the distance between the electrodes 82 and 84 is relatively small as compared to the dimensions of the laundry storing compartment 17.

Fig. 4 depicts a detailed sectional side view of the electrodes 82 and 84. The electrodes 82 and 84 are parts of a conductivity measurement system. Said conductivity system is provided for determining the humidity of the laundry 19 inside the drum 18 and/or for estimating the amount of load in the laundry drum 18. In an embodiment, the electrical conductance and/or resistance between the electrodes, in particular its level of electrical noise and/or fluctuation during the operation of the laundry treatment apparatus can be measured for this purpose. Alternatively or in addition, it is also possible to measure a voltage and/or a current between the electrodes. Preferably, the measurement is done during those stages of a laundry treatment program, when the laundry is not or not yet completely dry, such as at the beginning of a drying program. The wet load can connect electrically the first electrode 82 to the second electrode 84, when a part of the wet load touches simultaneously the first electrode 82 and the second electrode 84. When the wet load in the laundry drum 18 does not touch simultaneously the first electrode 82 and the second electrode 84, e.g. due to the movement of the laundry inside the drum, then a peak (e.g. of low conductance and/or high resistance) is detected by the conductivity system. It has been found that there is a correlation between the number and/or frequency of peaks and/or electrical noise of the electric signal and the amount of load in the laundry drum 18. The smaller the load is inside the laundry drum 18, the higher is the number or frequency of detected peaks and/or the electrical noise measured by the conductivity system. Further, it has been found that also the value of peaks of a signal related to the detected electric resistance and/or conductivity, and also the area subtended or enveloped by peaks of a signal related to the detected electric resistance and/or conductivity are related to the amount of load inside the laundry drum 18.

Further, it has been found that a signal related to the detected electric resistance and/or conductivity, particularly the maximum conductivity value measured at peaks, and also the average value of a signal related to the detected electric resistance and/or conductivity are related to the humidity of the laundry inside the laundry drum 18. In particular, it has been found that the higher the humidity of laundry is inside the laundry drum, the higher are the average and peak values of the detected conductivity.

In embodiments of the laundry treatment apparatus according to Figs. 3 and 4, evaluating the noise and/or fluctuation of the detected electric resistance and/or conductivity comprises one or more of the following:

- measuring the value of peaks of an electric signal corresponding to the detected electric resistance and/or conductivity,

- measuring the number of peaks within a time span of an electric signal corresponding 5 to the detected electric resistance and/or conductivity,

- measuring the area subtended by peaks of an electric signal corresponding to the detected electric resistance and/or conductivity, and/or

- deriving (e.g. in the control unit 51) from the measured signals a signal or quantity corresponding to the amount of load inside the drum 18,

o - deriving (e.g. in the control unit 51) from the measured signals a signal or quantity corresponding to the humidity of the laundry 19 inside the drum 18.

Fig. 5 is a schematic sectional side view of a laundry treatment apparatus 2 similar to that shown in Fig. 3 but with a laundry water content sensor 200 and a load sensor 220.

5 Preferably, the laundry water content sensor 200 is a contactless sensor, i.e. a sensor that can determine the water content of the laundry 19 inside the laundry storing compartment 17 without the need of getting into direct contact with the laundry 19.

In the embodiments, the laundry water content sensor 200 generates and outputs a laundry o water content sensor signal 218 that is received by the control unit 51 , where the signal can be used for controlling the operation of the laundry treatment apparatus 2 and/or for controlling at least subroutines of one or more laundry treatment programs. In particular, the control unit 51 may adjust the following parameters depending on the received laundry water content sensor signal 218:

5 - the estimated time until the end of a laundry treatment cycle,

- the flow rate of drying air A,

- the drum rotation speed, e.g. in laundry treatment programs for tumbling or spinning,

- the operation parameters of the heat pump compressor 14, such as its speed or the temporal variation of its input power,

o - the heating power provided for laundry drying, in particular for heating the drying air

A.

Preferably, the signal 218 from the laundry water content sensor is related to the total amount of water contained in the laundry 19 inside the laundry storing compartment 17, so 5 that during a laundry treatment program for tumbling and/or drying, the control unit 51 can estimate the total amount of water that is stored by the laundry or articles in the compartment 17 and remains to be removed from the laundry or articles. By comparing the estimated the total amount of water contained in the laundry at two or more points in time, the control unit may further estimate the profile of the past, current, and/or future rate of water removal achieved by a given laundry treatment program. It may 5 also be provided to estimate the total amount of water that has been removed during a treatment cycle and/or a certain period of time of laundry treatment.

Preferably, the specific design and program parameters of a machine such as available heating power, drum rotation speed and/or compressor power are taken into account when l o estimating the water removal rate or the amount of water that has been removed. More preferably, the water removal rate achieved by a specific program of a specific machine may be known or assumed a priori from the machine design.

From the estimated total amount of water contained in the laundry together with the known and/or estimated and/or assumed water removal rate, the estimated time until the end of the laundry treatment cycle (here: tumbling or drying) can be derived. The so estimated time to cycle end may be used, e.g., for controlling operation parameters of the laundry treatment apparatus and/or for providing information to the user about the remaining time required for a laundry treatment.

20

In embodiments, the flow rate of drying air (A) may be increased with decreasing laundry water content and/or increasing amount of removed water so as to ease and/or speed up the removal of remaining water in almost dry laundry. Preferably, the drying air flow is adjusted over time depending on the water content sensor signal 218 and other operation

25 parameters of the laundry treatment apparatus such as drum rotation speed, drying air A heating power, power and/or speed of the heat pump compressor 14. In another embodiment, the speed of the drying air fan 8 is increased with decreasing laundry water content and/or increasing amount of removed water and/or when the water removal rate is high in order to compensate for the increased pressure drop that may occur in the drying air circuit e.g. due to clogging of air filters by moisture.

Preferably, the rotation speed of a laundry drum 18 is adjusted depending on the signal 218 of the water content sensor 200. More preferably, the drum rotation speed is reduced with decreasing amount of water detected in the laundry, because a lower rotation speed may be 35 appropriate for moving the laundry that becomes lighter with decreasing water content along the treatment cycle. Furthermore, the speed and/or power of the heat pump compressor 14 may be adjusted according to the water content sensor signal 218. In particular, the compressor speed and/or power may be reduced with decreasing amount of remaining water in the drum (laundry/articles), since a smaller refrigerant flow rate is well matched with the lower 5 humidity level exiting the drum and entering the evaporator. Preferably, the power for heating the drying air A and/or the drying air temperature are also adjusted depending on the estimated amount of remaining water in the laundry and/or the estimated amount of removed water and/or the estimated water removal rate. o An estimation of the laundry water content at the beginning of, e.g., a laundry drying cycle by means of the laundry water content sensor 200 can provide an accurate value of the whole amount of water removed and/or to be removed from the laundry. The obtained knowledge about the total amount of water removed and/or to be removed can implicitly provide knowledge about the amount of water available for self-cleaning cycles, in 5 particular when also the condensation efficiency of the laundry treatment apparatus

machine 2 is known a priori, e.g. from its design parameters. The control unit 51 may use this information to control self-cleaning cycles carried out by the laundry treatment apparatus 2. Self-cleaning cycles are for removing fluff from a drying air fluff filter of the apparatus by flushing the filter with a liquid, preferably water and highly preferably water o condensed during the laundry drying process

Some specific embodiments making use of such information are explained in the following. Suppose that the apparatus 2 is arranged to normally do one self-cleaning cycle after each laundry drying cycle. Further suppose that a condensate water amount V0 is the optimal amount of water required for a self-cleaning cycle (e.g. washing of filters 22) and 5 that water amount VI is the amount of water estimated as being available for self-cleaning after a drying cycle (for example calculated from the total amount of water removed from the laundry multiplied by condensation efficiency).

- If V0 ~ VI, then the available amount of water is appropriate for one washing cycle, so that the apparatus can perform the self-cleaning cycle after the drying cycle as usual. 0 - If V0 » VI, then additional self-cleaning cycle(s) could be added when appropriate.

For example, in case of V0 = 2 x VI one more self-cleaning cycle could be done in order to keep filters clean.

- If V0 « VI, then the available amount of water is not sufficient for one self-cleaning cycle, so that the self-cleaning may be ineffective and the filters may not be cleaned 5 properly. As a result of multiple such ineffective cycles dirt may accumulate on the filters and the performance of the laundry treatment apparatus 2 may become unsatisfactory. As a possible solution, the control unit may delay self-cleaning until enough water for an effective self-cleaning is available. Furthermore, the user may be given an alarm signal indicating that filters need to be cleaned manually since self- cleaning was not possible. Preferably an alarm is given when self-cleaning was skipped several times. More preferably the user is warned that the laundry treatment apparatus 5 2 may need inspection when the frequency of skipped self-cleaning cycles is rises above a certain threshold which indicates a possible defect.

In an embodiment, the load sensor 220 shown in the embodiment of Fig. 5 may be a conductivity measurement system as shown in Fig. 4 and described above. Having the0 height level in the laundry storing compartment 17 determined for example by the load sensor being a conductivity sensor, the water content, and, optionally, the type of laundry, it is possible to estimate e.g. the weight and/or volume and/or mass of the laundry load. In a further embodiment, an acoustic system such as an ultrasonic sensor may be used for measuring the height level of laundry 19 loaded into the laundry storing compartment 17.5

The load sensor 220 may also be embodied as a weight sensor associated to the laundry storing compartment 17, in particular the drum 18.

In another embodiment the load sensor (not necessarily load sensor 220 shown in Fig. 1) o may comprise a circuitry for measuring electrical parameters of the drum motor such as the electric current and/or the induced voltage. The electrical current through the electric drum motor is at least approximately proportional to the torque of the electric drum motor. For example, the electric current measured gives a measure of the torque of the electric drum motor and from the torque the amount of load may be determined. In further embodiments, 5 the torque of the electric drum motor may be detected and/or calculated differently, for example by means of a torque sensor associated to the drum motor. In the embodiment shown in Fig. 1 the detection of the load amount or load mass is for example provided by a load sensor formed of the electronic board or inverter 152 which sends a signal corresponding to the torque of drum drive motor 150 to the control unit via line 154.

o Control unit 51 processes the torque signal 154 for determining the load or mass of the laundry and/or articles in the drum 18.

In a further embodiment, the load sensor 220 comprises one or a plurality of temperature sensors. The amount of load in the laundry storing compartment may be determined from 5 the temperature difference of the drying air A between an inlet and outlet of the laundry storing compartment 17. The temperature difference is related to the amount of water extracted from the laundry and decreases with decreasing laundry load because of a reduced heat exchange between the air flow and the reduced amount of laundry. Further, also the temperature of the air flow at the outlet of the laundry storing compartment 17 can be used alone for estimating the amount of load in the laundry storing compartment 17.

5 In a further embodiment, the amount of load laundry storing compartment 17 may be detected by the temperature difference of the air flow between an inlet and outlet of the first heat exchanger 10.

It is to be understood that the load sensor 220 may be embodied as a single sensor or may o comprise a plurality of sensors measuring one or more quantities that are appropriate for determining the load of laundry in the laundry storing compartment 17 as, e.g., explained above. In embodiments, the load sensor 220 may further comprise processing circuitry generating one or more load sensor signals by combining signals from the different individual sensors it comprises. It is to be understood that the load sensor signal 228 may5 be a signal from a single sensor and/or may comprise a plurality of signals from said

plurality of sensors and/or may comprise one or more combined and/or preprocessed signals in said processing circuitry.

In embodiments, the load sensor 220 may consist of or comprise at least one sensor that is o used also for other purposes in the laundry treatment apparatus 2. For example, existing temperature sensors 41 in the heat pump system or in the drying air flow A may be reused to form the load sensor 220.

Preferably, the laundry water content sensor 200 may be adapted for determining not only 5 a laundry water content but also the laundry load inside the laundry storing compartment.

More preferably, different characteristics (such as average value and amplitude and/or frequency of variations) of the one or more signals generated by the laundry water content sensor are evaluated, e.g. in the control unit 51, to determine both a laundry water content and a laundry load value.

0

The load sensor 220 serves for determining the amount of laundry 19, i.e. the "load", inside the laundry storing compartment 17. Preferably, the load sensor 220 provides a load sensor signal 228 to the control unit 51. The control unit may use the signal 228 to derive a quantity that is directly related to the amount of laundry, such as, e.g., the weight, the 5 volume, and/or the mass of the laundry inside the laundry storing compartment. Knowing the amount of laundry that is loaded in the laundry storing compartment is beneficial for controlling operation parameters of the laundry treatment apparatus 2, such as the speed and/or acceleration and/or deceleration of drum rotation during, e.g., tumbling or spinning.

Determining the amount of load in the laundry storing compartment 17 may include receiving information about the amount of load through a user selection of data. A

5 preferred way to determine the amount of load by the user may include the provision of a button on the input section 66 which permits the user to select the amount of load. The button may comprise, for example, two positions corresponding to the choice of a "full- load condition" or a "half-load condition" which may depend on the quantity of laundry loaded into the laundry storing compartment 17 by the user. In other embodiments, the user o input may be combined with signals obtained from the load sensor 220.

In an embodiment, a signal and/or quantity corresponding to the humidity of the laundry 19 inside the laundry storing compartment 17 is derived by the control unit 51 from the laundry water content sensor signal 218 and the load sensor signal 228. For example, the 5 control unit 51 may determine the total amount of water and the load of laundry inside the laundry storing compartment 17. In particular, it may obtain the mass of water and the mass of the laundry load, both, e.g., in units of kg (or lbs.). Dividing the total amount of water by the load of laundry yields a value quantifying specific humidity of the laundry, such as kg of water per kg of laundry, for example. Preferably, the resulting specific o humidity value may be used for controlling the operation of the laundry treatment machine.

Such controlling may comprise, for example, one or more of the following:

- terminating a laundry drying cycle, when the laundry humidity reaches or drops below a predetermined humidity threshold,

- stopping laundry treatment with steam from the steam generation unit 90, when the 5 laundry humidity reaches or rises above another predetermined humidity threshold,

- adjusting the rotation speed and/or acceleration and/or deceleration of the drum 18,

- estimating and/or displaying the time until the end of a laundry treatment cycle,

- adjusting the flow rate of and/or heating energy provided for the drying air A,

- speed of or power provided to the heat pump compressor 14, and/or

o - adjusting the temperature and/or flow rate of steam generated by the steam generation unit 90 for laundry treatment.

Fig. 6 shows a sectional view of the laundry storing compartment 17 inside a laundry drum 18 with a contactless laundry water content sensor 200 using electromagnetic radiation for 5 measuring the laundry water content. As can be seen, the sensor 200 consists of a high frequency (HF) wave emitter 202 and a separate high frequency wave receiver 208. In this embodiment, the emitter 202 generates and emits electromagnetic waves 216. A portion of the emitted waves 216 is absorbed by the humid laundry 19 or leaves the laundry treatment apparatus and does not reach the receiver 208. Another portion of the emitted waves 216 is transmitted through the laundry 19 and forms a transmitted electromagnetic signal T that reaches the receiver 208. Yet another portion of the emitted waves 216 is reflected by the humid laundry and/or parts of the laundry treatment apparatus 2 (e.g. by the drum 18) and forms a reflected signal R also reaching the receiver 208. Note that in the present context, the term "reflection" is meant to comprise not only reflection in its narrow sense but also refraction as well as absorption with subsequent re-emission with unchanged and/or changed frequencies.

Preferably, the frequency or frequencies of the electromagnetic radiation emitted by the emitter 202 and/or the frequency or frequencies which the receiver 208 is tuned or are adjusted so that the radiation interacts preferably with the water inside the laundry instead of other material such as, e.g., textiles fibers. Preferably, the high frequency or the high frequencies used by the laundry water content sensor 200 is/are in the range of 900 to 930 MHz and/or in the range of 2.4 - 2.5 GHz, and/or in the range of 5.7 - 5.9 GHz. More preferably, the high frequency or the high frequencies used by the laundry water content sensor 200 is/are in the range of 902 to 928 MHz and/or in the range of 2.400 - 2.483 GHz, and/or in the range of 5.725 - 5.875 GHz.

Preferably, the laundry water content sensor 200 is a contactless water content sensor as, e.g., in the embodiment shown in Fig. 6. The components 202, 208 of a contactless laundry water content sensor 200 do not need to get into direct contact with the laundry 19 for measuring the laundry water content.

In the embodiment shown in Fig. 6, the components 202 and 208 of the water content sensor 200 are placed outside the laundry storing compartment 17. In this way, the sensor components can be well protected against humidity, pollution by fluff and mechanical stress created by the laundry. As an advantage, the sensor may reach an increased life time and/or can be designed to be more cost efficient.

As an additional advantage, mounting the laundry water content sensor 200 outside the laundry storing compartment 17 may avoid or reduce "blind zones" within which the sensor cannot detect laundry water content. This is illustrated in Figs. 11a and 1 lb. Figure 11a shows a situation where a contactless laundry water content sensor based on emission and reception of HF electromagnetic waves 216 is mounted inside the laundry storing compartment 17. Depending on the sensor design, there are regions D (the "blind zones"), into which no electromagnetic waves 216 are emitted and/or from which no

electromagnetic waves 216 can be received. Fig. 1 lb shows the same design except that the laundry water content sensor 200 is located outside the laundry storing compartment 17. As depicted by the figure, the size of the "blind zones" D is significantly reduced by this arrangement.

Returning to Fig. 6 it can be seen that, with the HF electromagnetic wave emitter 202 and receiver 208 being mounted outside of the laundry storing compartment 17, it is preferable to design the laundry storing compartment 17 in such a way that HF electromagnetic waves 216 can pass through the respective portions of the walls 17a of the laundry storing compartment 17. In particular, the laundry drum 18, a lateral wall of the laundry drum 18, and or a lateral wall 17a of the laundry storing compartment 17 (or appropriate portions thereof) could be made of plastics or plastic-polymeric material such as PTFE (e.g.

Teflon), PE, PP, and/or polyamides.

In another embodiment of the laundry water content sensor 200, which is shown in Fig. 7, a HF electromagnetic wave emitter 202 and a HF electromagnetic wave receiver 208 are located close to each other on the same side of the laundry storing compartment 17.

Preferably, emitter 202 and receiver 208 are attached to each other or integrated to form a single sensor unit. More preferably, they are mounted to a common PCB or substrate and/or are integrated in a common housing. In this way the handling of the sensor, such as its mounting into the laundry treatment apparatus, its calibration, and/or its connection to the control unit 51, can be simplified. Furthermore, costs may be reduced e.g. by saving cost for a second housing. Since in the embodiment according to Fig. 7, there is no direct path of HF electromagnetic wave transmission from the emitter 202 through the laundry storing compartment to the receiver 208, the laundry water content sensor 200 according to this embodiment is preferably adapted to detect a reflected electromagnetic wave signal R.

Figs. 6 and 7 also depict the laundry water content sensor 200 arranged in a lower region of the laundry storing compartment 17, that is shifted towards the region towards which the laundry inside the laundry storing compartment 17 would be pushed by gravity. Preferably, at least one component 202, 208 of the laundry water content sensor 200 or the laundry water content sensor 200 as a whole is arranged in a lower region of the laundry storing compartment 17. This is beneficial if the accuracy of the measurements of the sensor 200 or at least one its components 202, 208 depend on the distance to the laundry. Furthermore, such an arrangement can help to increase the probability that a significant amount of the laundry is within the active area/volume of the laundry water content sensor 200, i.e. the area/volume within which laundry water content can be detected effectively by the laundry water content sensor 200.

Figs. 8, 9, and 10 illustrate further embodiments of a contactless laundry water content sensor 200 using emission and reception of HF electromagnetic waves. Fig. 8 is a more detailed view of a setup with an HF electromagnetic wave emitter 202 and an HF electromagnetic wave receiver 208 as shown in Fig. 7. As can be seen, the emitter 202 comprises an HF emitter circuitry 204 and an HF emitter antenna 206, and the receiver 208 comprises an HF receiver circuitry 210 and an HF receiver antenna 212. In an embodiment according to Fig. 9, the emitter circuitry 204 and the emitter antenna 206 are integrated on a common PCB and/or HF emitter substrate 203. In the same way, the receiver circuitry 210 and the receiver antenna 212 are integrated on a common PCB and/or HF receiver substrate 209. Both substrates 203 and 209 are assembled onto a common PCB and/or into a common contactless water sensor housing 201. Fig. 10 depicts an embodiment of a contactless water sensor 200 realizing a further level of integration by combining the emitter circuitry 204 and the receiver circuitry 210 on a common PCB or common substrate 215 and adding a common HF emitter and receiver antenna 214 to the same PCB or substrate 215. As will be understood by a person skilled in the art, further levels of integration can be achieved in other embodiments, e.g. by sharing additional parts of circuitry between the HF electromagnetic wave emitter 202 and the HF electromagnetic wave receiver 208, such as, e.g., for power supply and/or signal conversion. In particular, it may be advantageous to design an integrated circuit (IC) comprising all or most of the electronics needed by the emitter 202 and/or the receiver 208. As mentioned above a higher level of integration can yield cost reductions and/or simplifications regarding the handling of the sensor 200 (e.g. mounting, calibration, connectivity with other components).

With reference to Fig. 12 an exemplary processing routing for determining the humidity of the laundry (can also be denoted as 'moister content of the laundry') is explained in more detail. The graph of Fig. 12 shows in relative units the relation between water content determined by the water content sensor 200, the load weight or mass determined by the load detector (e.g. the current and/or voltage sensor implemented in electronic board 152) and the humidity of the laundry in the drum. The depicted graph or relation is generated as a mathematical function Laundry Humidity LH = F(load, water content). However the relation can also be established by experimental results (and interpolation therebetween) which are stored in a look-up table 52 (see Fig. 1) to which the control unit 51 has access. Or the analytical function is derived by an interpolation function using experimental results. Thereby the humidity of the laundry is more accurately determined by detection and evaluation and/or processing of the load signal (from 220) and water content signal (from 200). Having in mind that the humidity is the relevant value for the user in view of the laundry states 'dry', 'cabinet dry', 'ironing dry' or a laundry refreshment program in which a minimum humidity has to be reached, the operation of the laundry treatment apparatus can be optimized. The optimized intended drying or humidity (wetting) state can be determined and reached by the apparatus more exactly what - at least in average of several operation runs - reduces treatment time and energy required.

With the above measurements it can be said that the laundry load (mass of laundry) is the sum of the laundry dry load and the water content (mass of water) bound in the laundry. The humidity then could be assumed to be the ratio of current water content of the laundry / maximum storable water content of the laundry. However for laundry the humidity, in particular the residual humidity (cabinet dry, ironing dry ...), depends on the laundry type. To take into account this dependency, the method for determining the humidity and determining the laundry state at which a specific condition is met (cabinet dry, ironing dry ...) can further process the water content and the laundry load in dependency of the laundry type.

The laundry type is for example input by the user via the control panel 66 or it is determined from the temporal progress of the drying process. Then different functions LH or look-up tables are available in dependency of the laundry type to further improve the accuracy in determining the humidity as a value used to terminate the drying process or to change from one sub-routine (e.g. drying) to another sub-routing (e.g. anticrease tumbling).

It is to be noted that such determination and/or monitoring of the laundry humidity and/or of the water content is fully applicable in washing machines and/or washer-dryers. For example the humidity during a spinning sub-routine can be monitored for achieving a predetermined humidity by the spinning, in particular by the final spinning.

Fig. 13 is a diagram showing how in an embodiment of the laundry treatment apparatus 2 having a heat pump system (10, 12, 14, 16) for drying air drying the drying air flow rate can be controlled by the control unit 51 in dependency of the laundry water content. The solid line of the diagram indicates the variation over time of the laundry water content in the laundry storing compartment 17 as determined from the laundry water content signal 218 and/or the load detector signal 228 according to the arrangements explained above. The dotted line depicts the temporal air flow rate profile as adjusted by the control unit 51 in response to the laundry water content.

As can be seen, the drying air flow rate is low when the laundry water content is high, e.g. 5 at the beginning of a laundry drying cycle. Since the heat that can be absorbed from the drying air stream by the heat exchanger 10 is limited, the rate of water that can be removed from the drying air is also limited. On the other hand, the amount of water absorbed by a given volume of drying air A passing through the laundry storing compartment 17 is relatively high when the laundry water content is high. Thus, for the high laundry water o content at the beginning of the drying cycle, a relatively low flow rate of drying air A is sufficient to reach a laundry drying rate at or close to the maximal possible value, depending on the design of the laundry treatment apparatus 2.

With decreasing laundry water content, i.e. when the laundry becomes drier, e.g. in the 5 course of a laundry drying program, the rate of water taken up by the drying air A passing the laundry storing compartment 17 decreases. Therefore, the drying air flow can be increased in order to keep a high laundry drying rate. In the example of Fig. 13, the drying air flow rate is increased by the control unit 51 when the water content drops below a certain threshold (e.g. the first predetermined water content value Wl). This increase of the o drying air flow rate corresponds the upwards step of the dotted line in the diagram. Since the drying air flow is kept at a low rate as long as possible and only increased when and as much as necessary in order to keep a designated laundry drying rate, the energy consumed by the drying air fan and thus the total energy consumption of the laundry treatment apparatus can be reduced as compared to prior art not having this kind of drying air flow 5 rate adjustment.

While the diagram of Fig. 13 and the above description applies to a laundry treatment apparatus 2 having a heat pump system (10, 12, 14, 16) for drying air drying, it is to be understood that the same principle is fully applicable also to embodiments of the laundry o treatment apparatus 2 wherein the drying air is cooled and/or dehumidified in a heat

exchanger by means of a cooling air stream.

In an embodiment of the laundry treatment apparatus 2 wherein the laundry storing compartment 17 is or comprises a rotatable laundry drum 18, the drum rotation speed is 5 beneficially selected and/or adjusted in dependency of the laundry water content

determined from the laundry water content signal 218 and optionally from the load detector signal 228 according to the arrangements explained above. Fig. 14 is a diagram depicting an example of the temporal variations of the determined laundry water content and the adjusted drum rotation speed, both in relative units. The temporal profile of the laundry water content (solid line) is the same as in Fig. 13. As shown by the dotted line, the drum rotation speed is adjusted to a relatively high value, when the laundry water content is relatively high. This is because due to gravity the wet laundry tends be compressed at the bottom of the drum and needs to be moved and mixed quickly in order to enable efficient penetration of and water removal by the drying air. As the laundry water content decreases, in particular towards the end of a laundry drying cycle, the laundry gets dryer and less compressed by gravity, thereby allowing drying air to pass through it more easily. Thus, less movement and mixing of the laundry by means of drum rotation is required for efficient laundry drying, so that the drum speed can be adjusted and/or switched to a lower value when the laundry water content decreases, e.g. drops below a certain threshold (e.g. a second predetermined water content value W2). This is shown in Fig. 14 by the downwards step of the dotted line. Since the drum motor 150 contributes significantly to the total energy consumption of the laundry treatment apparatus 2, adjusting the drum rotation speed in dependency of the laundry water content allows to reduce the overall energy consumption of the apparatus. Furthermore, a reduced drum rotation speed leads to a reduced friction between the pieces of laundry 19 in the laundry drum 18, which has the beneficial effect of reducing the amount of created lint and fluff.

When the water content detection by the contactless HF electromagnetic wave detector is implemented in a washing machine or washer-dryer, the control unit can evaluate the signal to determine the degree of dehydration during a spinning phase. Such the spinning can be stopped when the laundry is sufficiently dehydrated after water extraction and energy for driving the drum at spinning speed can be saved and respective time of spinning can be reduced.

As will be easily understood by a person skilled in the art, the described mechanism of adjusting the drum rotation speed in dependency of the laundry water content applies for embodiments of the laundry treatment apparatus 2 having a heat pump system (10, 12, 14,

16) for drying air cooling/drying as well as for embodiments wherein the drying air is cooled and/or dehumidified in a heat exchanger by means of a cooling air stream.

In an embodiment of the laundry treatment apparatus 2, the drum 18 and the drying air blower 8 are driven by the same motor 150 (see above). In this case, drum rotation speed and blower speed - and thus also drying air flow rate - are directly related to one another. According to the above explanations and the example shown in Fig. 13, the drying air flow rate is preferably adjusted to a relatively low value while the laundry water content is relatively high, in particular at the beginning of a laundry treatment cycle, and increased when the laundry water content decreases. On the other hand, as exemplified in Fig. 14, the drum rotation speed is preferably reduced when the laundry water content becomes low, 5 i.e. towards the end of a laundry drying cycle. Thus, when the drum 18 and the blower 8 are driven by the same motor 150, it is preferable to jointly adjust the drying air flow rate and the drum rotation speed depending on the laundry water content. In an embodiment the blower 8 is driven by a motor that can be controlled by the control unit independent of the motor for driving the drum 18. In this way the speed, on/off periods and/or rotation o direction of the blower and the drum can be controlled independent of each other.

Preferably, the control unit 51 adjusts the speed of the motor 150 in dependency of the laundry water content, thereby adjusting both the drying air flow rate and the drum speed at the same time. 5 Fig. 15 depicts an example of the resulting temporal profiles of laundry water content

(solid line, again the same as in Figs. 13 and 14), drum speed (dotted line), and drying air flow rate (dashed line), all in relative units. In this example, a low motor speed is applied while the laundry water content is high, e.g. above an upper threshold (e.g. a third predetermined water content value W3), so that both drum speed and drying air flow rate o are low at the beginning of a laundry drying cycle. In this example the water content value coincides for drying air flow rate and drum speed, but in other embodiments where the drum and drying air fan are driven independently, the two W3 values may be different ones. This way of control avoids waste of motor energy and/or heating energy during the initial drying phase as explained above. When the laundry water content decreases, 5 preferably below said upper threshold, the speed of the motor 150 is increased, whereby drum speed and drying air flow rate are increased simultaneously. This is indicated by the simultaneous upwards steps of the dotted and dashed lines in the diagram.

As the laundry water content decreases further, preferably when it drops below a lower o threshold (e.g. a fourth predetermined value W4), the motor speed is decreased again, resulting in a simultaneous decrease of the drum speed and the drying air flow rate, as shown by the simultaneous downwards steps of the dotted and dashed lines in the chart. In that way, waste of energy and excessive fluff creation due to drum rotation can be avoided (see above).

Based on the laundry water content derived from the laundry water content signal 218 and/or the load detector signal 228 as explained above, the laundry drying rate can be estimated as the amount of removed water content per unit time. In an embodiment of the laundry treatment apparatus 2 exhibiting a heat pump system (10, 12, 14, 16) for drying the drying air A, the estimated laundry drying rate can be used by the control unit 51 for adjusting the speed of the heat pump compressor 14 as illustrated in Fig. 16. The dashed 5 line in the diagram depicts an example of the temporal profile of the estimated laundry drying rate (measured in kg/min) obtained during a drying cycle of the laundry treatment apparatus. The drying rate is for example the temporal gradient dW/dt of the negative water content value W (i.e. dW/dt is positive when the water content value W decreases). As can be seen, the drying rate is relatively low and then starts to rise at the beginning of o the drying cycle. This is because the heat pump system, the drying air A, and the laundry storing compartment 17 are in the heat-up phase and have not yet reached their designated operating temperature. After a certain period of time, when the target operating temperature is reached, the drying rate arrives at a maximum and then begins to decline again, because the water content of the laundry 19 decreases and the remaining water is 5 absorbed less efficiently by the drying air A.

The solid line shows an example of the adjusted heat pump compressor speed (in relative units). At the beginning of the drying cycle when the laundry drying rate is still relatively low (e.g. below a first predetermined temporal gradient of the water content value dWl/dt) o and/or increasing relatively quickly, the heat pump compressor speed is adjusted to a relatively high value (first and highest speed) so as to speed-up the warm-up phase thereby reducing the overall time needed for the laundry drying cycle. When the laundry drying rate approaches its maximum value (e.g. rises above the first predetermined temporal gradient of the water content value dWl/dt) and/or increases less quickly, the heat pump 5 compressor speed is reduced to an intermediate level (second speed lower than first speed) that is, however, still sufficient for drying the drying air A. This is indicated by the first step of the solid line. When the laundry drying rate returns to a relatively lower value (e.g. drops below a second predetermined temporal gradient of the water content value dW2/dt) and/or starts to decline relatively quickly, the speed of the heat pump compressor 14 is o further reduced to a third speed (lower than the second speed) (second step of the solid line), because less humidity needs to be removed from the drying air and/or in order to reduce the drying air temperature towards the end of the drying cycle.

Fig. 16 shows another embodiment of controlling the compressor speed as shown by the 5 dotted line. As before, the compressor speed is high (e.g. at maximum) in the heat-up period for heating up the heat pump system. When the temporal gradient of the water content value reaches a third water content value dW3/dt, the compressor speed is lowered to a first reduced speed. After some time, the temporal gradient of the water content value rises and reaches a fourth water content value dW4/dt, which is higher than the third water content value dW3/dt. To enable the heat pump system to remove the higher steam rate coming from the faster drying laundry, the condensation capacity of the evaporator is increased by increasing the compressor speed again to the higher speed (e.g. maximum speed).

When during the further progress of the drying the temporal gradient of the water content value falls again below a fifth water content value dW5/dt (which in this example is the same as dW4/dt), the speed of the compressor is lowered again to a second reduced compressor speed (which in this example is the same as the first reduced compressor speed). The laundry drying process further continues and when the temporal gradient of the water content value falls below a sixth water content value dW6/dt, the compressor speed is reduced to a third reduced compressor speed which is lower than the first and/or second reduced compressor speed. The lowered drying rate (water content gradient) is mainly contributed to the higher drying air flow resistance and correspondingly the drying air humidity removal capacity is adapted to the lower yield of air humidity

generation/transportation. At the same time the capacity of the condenser is reduced thus avoiding overheating of e.g. temperature-delicate laundry.

At the seventh water content value dW7/dt the control unit reduces the compressor speed to zero as the now residual water content of the laundry can be removed with the available cooling (water condensing) capacity of the evaporator and the residual drying air heating capacity of the condenser. (Note: Here and above the numbering first, second, third ... is a relative numbering to indicate the temporal sequence within the specific embodiment described.) All the above measures result in shortening the drying process and/or reducing the energy consumption of the drying process.

As a result, adjusting the heat pump compressor speed in dependency of the laundry water content (or more particularly, the estimated laundry drying rate, as in the above example) can reduce the overall drying cycle time as well as the total energy consumption of the laundry treatment apparatus 2.

In an embodiment, the laundry treatment apparatus 2 exhibits a heating element for heating the drying air A to be guided to the laundry storing compartment 17. Preferably, the heating power of the heating element is adjusted in dependency of the laundry water content derived from the laundry water content signal 218 and/or the load detector signal 228 as explained above. Fig. 17 is an example showing two different ways how this can be realized. The dashed line shows the temporal profile of laundry water content, for the sake of clarity again identical to the one displayed in Figs. 13, 14, and 15. In order to reduce the drying cycle duration and/or the overall energy consumption of the laundry treatment 5 apparatus 2, the heating power of the heating element starts at its maximal level and is then reduced step by step while the laundry water content decreases and less heat is required for removing the remaining moisture. In the embodiment shown at a fifth predetermined water content value W5 the heating power is reduced to a second power value lower than the maximum heating power, at a sixth predetermined water content value W6 the power is o reduced to a third heating power lower than the second heating power and at a seventh predetermined water content value W7 the heater is switched off. After switching the heater off, the residual heat in the system (e.g. laundry and laundry storing cabinet and/or condenser) and/or the residual cooling capacity of the heat exchanger (evaporator) is sufficient to further dry the laundry and/or to further remove humidity from the drying air.5

A first approach for reducing the heating power is indicated by the dotted line: The heating element or at least one branch of the heating element is periodically switched on and off, resulting in a reduced average heating power applied to the drying air flow. According to a second approach, indicated by the solid line, the heating element or at least one branch of o the heating element is continuously provided with an electrical power corresponding to the heating power that needs to be applied to the drying air flow. The latter approach is particularly beneficial because it eliminates the power peaks created by the periodic switching applied in the first approach, which may be problem for the user when operating the laundry treatment apparatus 2 together with other domestic appliances.

5

Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the o scope of the invention. Reference Numeral List:

2 laundry treatment apparatus 82 first electrode

3 casing 84 second electrode

4 heat pump system 40 88 nozzle unit

5 6 refrigerant loop 90 steam generation unit

8 blower 106 steam conduit

10 first heat exchanger 140 steamer tank

12 second heat exchanger 142 branching element

14 heat pump compressor 45 150 drum/blower motor

10 16 expansion device 152 electronic board

17 laundry storing compartment 154 signal, power and control line 17a laundry storing compartment wall 156 drum drive belt

18 laundry drum 200 contactless water content sensor

19 laundry 50 201 contactless water content sensor 15 20 drying air channel housing

20a battery channel 202 high frequency (HF)

20b rear channel electromagnetic wave emitter

20c rising channel 203 HF emitter substrate

20d front channel 55 204 HF emitter circuitry

20 22 fluff element 206 HF emitter antenna

30 condensate collector 208 HF electromagnetic wave receiver

36 drain pump 209 HF receiver substrate

40 condensate drawer 210 HF receiver circuitry

41 temperature sensor 60 212 HF receiver antenna

25 46 drain conduit 214 common HF emitter and receiver

50 drawer pipe antenna

51 control unit 215 contactless water content sensor

52 memory/look-up table common substrate

54 loading opening 65 216 electromagnetic waves

30 55 front door 218 water content sensor signal

56 top cover 220 load detector

58 left cover 228 load detector signal

60 front cover A drying air flow

62 front top panel 70 B refrigerant flow

35 64 drawer cover D region / blind zone

66 input section R reflected signal

70 front frame T transmitted signal

Claims

5 Claims:

0 1. Laundry treatment apparatus (2), in particular laundry dryer, washing machine or washer dryer, the laundry treatment apparatus comprising:

a casing (3),

a laundry storing compartment (17) arranged within the casing (3) for receiving laundry (19) to be treated,

5 a contactless laundry water content sensor (200) adapted to detect the amount of water contained in the laundry (19) stored in the storing compartment (17), and

a control unit (51) for controlling the operation of the laundry treatment apparatus (2) and adapted to receive a water content sensor signal (218) from the laundry water content sensor (200);

o characterized in that

the contactless water content sensor (200) comprises a high frequency electromagnetic wave emitter (202) and a high frequency electromagnetic wave receiver (208), and

the control unit (51) is adapted to select or adjust one or more of the following 5 parameters in dependency of the laundry water content sensor signal (218):

estimated time to end of laundry drying,

the drying air flow rate of drying air (A) for drying laundry, drum rotation speed for rotating the rotatable laundry storing compartment (17), o heat pump compressor (14) operation parameters of a heat pump system of the apparatus for heating the drying air,

heating power for heating drying air, and

self cleaning operation for removing fluff from a fluff filter (22) of the apparatus by flushing with a liquid.

2. Laundry treatment apparatus (2) according to claim 1, further comprising:

a load detector (220) adapted to detect the weight of laundry (19) stored in the laundry storing compartment (17),

wherein the control unit (51) is adapted to receive a signal (228) from the load detector, and

wherein the control unit (51) is adapted to process the signals (228, 218) from the load detector (220) and the laundry water content sensor (200) for determining a secondary parameter, which is depending on the load detector signal (228) and the water content sensor signal (218) and which is used by the control unit (51) for controlling a drying and/or spinning operation of the laundry treatment apparatus (2) by selecting or adjusting said parameter by the control unit.

3. Laundry treatment apparatus according to claim 1 or 2, wherein the at least one secondary parameter comprises one or more of the following:

- the humidity of the laundry (19),

- the absolute total water amount within the laundry storing compartment (17),

- the dry weight of the laundry (19),

- the distribution of the laundry (19) in the laundry storing compartment (17),

- the distribution of water within the laundry storing compartment (17), and

- the type of laundry (19),

4. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to receive the water content signal (218) and the load signal (228) and to process or evaluate the signals (218, 228) for determining a humidity value of the laundry stored in the laundry storing compartment (17).

5. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to determine a laundry load value using the load detector signal (228) and to adjust the laundry load value using the laundry water content sensor signal (218).

6. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to determine a laundry water content value using the laundry water content sensor signal (218) and to adjust the laundry water content value using the load detector signal (228).

7. Laundry treatment apparatus according to any of the previous claims, wherein the laundry storing compartment (17) is a rotatable drum (18) driven by a drum motor (150) and the load detector (220) is a detector (152) for detecting at least one of the drum motor voltage, current, power or magnetic value.

8. Laundry treatment apparatus according to any of the previous claims, comprising a or the drum motor (150) and an electronic board (152) for powering the motor, or 5 a variable speed drum motor (150) and an electronic board (152) for powering the motor to rotate with a controllable speed,

wherein the electronic board (152) sends one or more operational parameters or a torque signal to the control unit (51), such that the electronic board operates as or implements the load detector (220), and

o wherein the control unit is adapted to determine the load or mass of the laundry in the drum by evaluating or processing the one or more operation parameters or the torque signal received from the electronic board.

9. Laundry treatment apparatus according to any of the previous claims, wherein the5 high frequency(-ies) of the laundry water content sensor (200) is in the range of 900 - 930

MHz, in the range of 2.4 - 2.5 GHz, or in the range of 5.7 - 5.9 GHz.

10. Laundry treatment apparatus according to any of the previous claims,

wherein the laundry water content sensor (200) is adapted to detect the signal o absorption by the laundry, the signal reflection by the laundry, or the signal absorption and signal reflection by the laundry, or

wherein the laundry water content sensor (200) is adapted to detect the high frequency electromagnetic signal absorption by the laundry, the high frequency electromagnetic signal reflection by the laundry, or the high frequency electromagnetic 5 signal absorption and signal reflection by the laundry.

11. Laundry treatment apparatus according to any of the previous claims, wherein the high frequency electromagnetic wave emitter (202) or the high frequency electromagnetic wave receiver (208) comprises a planar antenna, in particular a patch antenna.

0

12. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to execute a laundry water content sensor calibration cycle when no laundry (19) is stored in the laundry storing compartment (17). 5

13. Laundry treatment apparatus according to any of the previous claims, wherein at least one of the sensors or sensor components (200, 202, 208, 220) is arranged in a lower region of the laundry storing compartment (17), where "lower region" is to be meant as the region towards which any solid body put into the laundry storing compartment (17) would be pushed by gravity.

14. Laundry treatment apparatus according to any of the previous claims, wherein the 5 control unit (51) is adapted to implement the control by one or more of the following:

increasing the drying air flow rate or drying air blower speed when the detected laundry water content sensor signal (218) falls below a first predetermined value (Wl) or is in a first predetermined value range, and

decreasing the drying air flow rate or drying air blower speed when the detected o laundry water content sensor signal falls below a second predetermined value (W4) or is in a second predetermined value range.

15. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to implement the control by one or more of the following: 5 increasing the drum rotation speed when the detected laundry water content sensor signal (218) falls below a third predetermined value (W3) or is in a first predetermined value range, and

decreasing the drum rotation speed when the detected laundry water content sensor signal falls below a fourth predetermined value (W2, W4) or is in a second predetermined o value range.

16. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to implement the control by:

decreasing the heating power when the detected laundry water content sensor signal 5 falls below a fifth predetermined value (W5) or is in a fourth predetermined value range, and optionally

further decreasing the heating power when the detected laundry water content sensor signal falls below a sixth predetermined value (W6, W7) or is in a fifth

predetermined value range.

0

17. Laundry treatment apparatus according to any of the previous claims, wherein the control unit (51) is adapted to implement the control by one or more of the following: decreasing the compressor speed of a heat-pump system of the apparatus or the compressing power of the compressor (14) when the detected laundry water content sensor 5 signal falls below a seventh predetermined value or is in a seventh predetermined value range or exceeds a first temporal gradient (dWl/dt) of the water content sensor signal, increasing the compressor speed of a heat-pump system of the apparatus or the compressing power of the compressor (14) when the detected laundry water content sensor signal falls below an eighth predetermined value or is in an eighth predetermined value range or exceeds a second temporal gradient (dW4/dt) of the water content sensor signal, and

further increasing/decreasing the compressor speed of a heat-pump system of the apparatus or the compressing power of the compressor when the detected laundry water content sensor signal falls below/rises above a ninth predetermined value or is in a ninth predetermined value range or falls below/rises above a third temporal gradient (dW2/dt; dW5/dt; dW6/dt) of the water content sensor signal.

18. Laundry treatment apparatus according to any of the previous claims, wherein at least parts of the laundry storing compartment wall (17a) or wall sections are transparent for passing the HF electromagnetic waves (216) through the wall.

19. Laundry treatment apparatus according to any of the previous claims, wherein the laundry treatment apparatus further comprises

a steam generation unit (90) for generating steam for laundry steam treatment, wherein the steam generation unit (90) is controlled by the control unit (51) and wherein the control unit (51) is adapted to select or adjust one or more of the following parameters in dependency of the laundry water content sensor signal (218) or the load detector signal (228):

flow rate of the steam provided for laundry treatment,

temperature of the steam provided for laundry treatment, or

one or more time intervals during which steam is provided for laundry treatment.