Patent Description:
In the recent years devices which heat rather than burn or cause combustion of a substance to generate a vapour or aerosol for inhalation by a user have become increasingly popular.

Such commonly used devices which heat rather than burn or cause a combustion of a substance may be tobacco-based device also known as heated tobacco products. These devices normally use tobacco and/or other suitable substance that is heated but not burned to create an inhalable aerosol. The tobacco and/or the other suitable substance may in general also be called an aerosol generating substance and the device in general may be called an aerosol generating device.

Normally, the aerosol generating substance is placed in a container, also called a stick or a tobacco stick, that can be inserted in and removed from the aerosol generating device by the user. Therefore, the stick or the tobacco stick is a consumable article.

In general, the user inserts the consumable article in the heating compartment of the aerosol generating device. The heating compartment of the aerosol generating device may also be called a heating chamber or an oven. When the user has inserted the consumable article in the heating compartment the user normally turns on the heating of the aerosol generating device for example by operating an operation button or gives instruction by other means to the aerosol generating device for turning on the heating of the aerosol generating device so that the aerosol generating substance can be heated. The turning on of the heating of the aerosol generating substance may also be called a start of an aerosol generating session. Thereafter, the user waits until the heating has progressed to a state at which it is possible that the aerosol generating substance that is heated generates an aerosol that can be consumed by the user.

This waiting time may be inconvenient for the user since normally the user likes to consume the aerosol as soon as possible after the consumable article is inserted in the heating compartment of the aerosol generating device. Even further, turning on the heating manually by the user requires providing an operation button or other means for giving an instruction to the aerosol generating device for turning on the heating of the aerosol generating substance which not only makes the structure of the aerosol generating device more complex but also reduces the convenience of the user in operating the aerosol generating device.

Document <CIT> relates to an apparatus for generating aerosol from an aerosolizable medium. The apparatus includes a housing; a chamber for receiving an article, a sensor and a cover system. The article includes an aerosolizable medium and a detectable element provided in association with the article. The sensor is configured to sense the detectable element when an article is received within the chamber. The cover system can be configured in at least a first configuration to substantially cover the sensor, and a second configuration, in which a field of view of the sensor is substantially without obstruction.

Document <CIT> relates to an aerosol generation device comprising a casing; an aperture in the casing through which aerosol generating material is insertable into the aerosol generation device; a closure moveable relative to the aperture between a closed position in which the closure covers the aperture, an open position in which the aperture is unobstructed by the closure, and an activation position that is different from the open position; and a detector arranged to detect movement of the closure from the closed position to the open position and between the open position and the activation position.

Therefore, there is a need for decreasing the time for generating an aerosol after the consumable article is inserted in the heating compartment of the aerosol generating device as well as for improving the user's convenience in operating the aerosol generating device and reducing the complexity of the aerosol generating device.

The mentioned problems and objects are met by the subject-matter of the independent claim <NUM>.

According to one aspect of the present invention there is provided an aerosol generating device comprising: a heating compartment extending along a first direction and comprising a base portion at a first end and an opening opposite of the base portion and arranged so that a user can insert, via the opening, a consumable article containing an aerosol generating substance; protection means for exposing and covering said opening of the heating compartment, a heater configured to supply heat to the heating compartment to thereby heat the aerosol generating substance in the consumable article; and
a detection means arranged outside the heating compartment and configured to detect whether a consumable article has been inserted in the heating compartment, wherein the detection means comprises at least one hall sensor and at least one magnet, said hall sensor and said magnet being arranged outwards of the heating compartment on opposite sides of the heating compartment in a second direction which is perpendicular to the first direction.

According to a further aspect of the present invention there is provided a system comprising the aerosol generating device according to the previous aspect and a consumable article, said consumable comprising aerosol generating substance and a metal foil.

Embodiments of the present invention which are presented for better understanding the inventive concept of the present invention, but which are not to be seen as limiting the present invention, will now be described with reference to the figures in which:.

<FIG> shows a schematic view of the aerosol generating device <NUM> according to the embodiment of the present invention.

The aerosol generating device <NUM> according to the embodiment of the present invention is a handheld device with an elongated pebble-like shape and comprises a housing portion <NUM> and an access portion <NUM>. The access portion <NUM> is in the top part of the aerosol generating device <NUM>. The access portion <NUM> comprises protection means <NUM> for exposing (or opening) and covering (or closing) an opening <NUM> to a heating compartment of the aerosol generating device <NUM>. The access portion <NUM> may further comprise other means, electrical or mechanical means, for moving or supporting the movement of the protection means <NUM>, sensing (or determining) the position of the protection means <NUM> and the like. Such means for sensing (or determining) the position of the protection means <NUM> are also called here below sensing means. In the heating compartment, a user may place at least one consumable article <NUM> comprising an aerosol generating substance when the opening <NUM> is exposed.

<FIG> shows schematic view of the consumable article <NUM> according to the embodiment of the present invention. The consumable article <NUM> may be a stick or a tobacco stick comprising tobacco and/or other suitable substance that is heated but not burned in the heating compartment to create an inhalable aerosol. The consumable article <NUM> may further comprise a flavour adding substance. The consumable article <NUM> may have an elongated form, for example a cylindrical form as shown in <FIG>. The consumable article <NUM> may be partitioned in two parts: in the first part <NUM> the aerosol generating substance is placed while the second part is a filter portion <NUM>. In some embodiments of the present invention the consumable article <NUM> may further comprise a metal foil, for example aluminium foil. The metal foil may stop the consumable article <NUM> from being combustible.

A system comprising the aerosol generating device <NUM> as described herein and the consumable article <NUM> as described herein comprise a system for generating an aerosol generating substance according to the embodiment of the present invention.

As further shown in <FIG> the aerosol generating device <NUM> may comprise on the outer side of the housing portion <NUM> means <NUM> comprising one or more input means (comprising for example one or more buttons) for giving instructions to the aerosol generating device <NUM>, for example instructions for outputting a battery level information, and/or one or more output means for indicating different information to the user, such as battery level information, possible error information and so on. The output means may be any suitable output means, for example a liquid crystal display (LCD display) or LED display, or one or more indicators, for example lamps or light emitting devices (LEDs). However, such input means and/or output means are to be seen as optional means that are by no way limiting to the present invention.

The protection means <NUM> for exposing (or opening) and covering (or closing) an opening <NUM> to a heating compartment of the aerosol generating device <NUM> may comprise for example a slider <NUM> as shown schematically in <FIG>. The slider <NUM> may be moved, for example by sliding, between a first position and a second position so that the opening <NUM> of the heating compartment is covered when the slider is in the first position and exposed when the slider is in the second position. The slider <NUM> being in the first position is also be referred here below as the slider being closed and the slider <NUM> being in the second position is also be called here below as the slider <NUM> being opened.

<FIG> shows a schematic view of the aerosol generating device <NUM> with the heating compartment <NUM> according to the embodiment of the present invention when the slider <NUM> is in the first position so that the opening <NUM> is covered by the slider <NUM>. <FIG> shows a schematic view of the aerosol generating device <NUM> according to the embodiment of the present invention when the slider <NUM> is in the second position so that the opening <NUM> is exposed. When the opening <NUM> is exposed the user can insert the consumable article <NUM> in the heating compartment <NUM>.

In other embodiment of the present invention the protection means <NUM> may comprise, for example, a cover lid or a trap door <NUM> that can at least partly be removed from the housing portion <NUM> as shown schematically in <FIG>. The cover lid, or trap door <NUM> is arranged to be movable between a first position and a second position so that the opening <NUM> of the heating compartment <NUM> (not shown in <FIG>) is covered when the cover lid or the trap door <NUM> is in the first position and exposed when the cover lid or the trap door <NUM> is in the second position.

<FIG> shows a schematic view of the aerosol generating device <NUM> according to this embodiment of the present invention when the cover lid or trap door <NUM> is in the first position so that the opening <NUM> is covered by the cover lid or trap door <NUM>. <FIG> shows a schematic view of the aerosol generating device <NUM> according to this embodiment of the present invention when the cover lid or trap door <NUM> is in the second position so that the opening <NUM> is exposed. When the opening is exposed the user can insert the consumable article <NUM> in the heating compartment <NUM>.

The housing portion <NUM> of the aerosol generating device <NUM> may have a smooth outer surface which together with the elongated pebble-like shape provides a physical ergonomic advantage for the user. The housing portion <NUM> houses at least the mentioned heating compartment <NUM> and houses further components of the aerosol generating device <NUM> as elaborated below.

<FIG> shows schematically a cross-sectional view of the of the aerosol generating device <NUM> of the embodiment of the present invention along the elongated direction of the aerosol generating device <NUM>.

As elaborated above the housing portion <NUM> of the aerosol generating device <NUM> houses the heating compartment <NUM>, also called here below a heating chamber or an oven. The heating compartment <NUM> may be such that the user can place one consumable article <NUM> at a time or the user may place more than one consumable articles <NUM> at a time in the heating compartment <NUM>. The heating compartment <NUM> may also have an elongated cylindrical form as the consumable article <NUM> but may also have a different elongated form. The form of the consumable article <NUM> and the heating compartment <NUM> are not to be seen as limiting to the concept of the present invention.

The heating compartment <NUM> extends along a first direction, which is denoted in <FIG> as x-direction. The first direction follows the elongated form of the aerosol generating device <NUM>, or in other words, the aerosol generating device <NUM> is elongated along the first direction. The heating compartment <NUM> comprises a base portion <NUM> at a first end and the above-mentioned opening <NUM> at the second end. The opening <NUM> is opposite of the base portion <NUM>. The heating compartment <NUM> comprises further one or more side walls. For example, the heating compartment <NUM> comprises a cylindrical side wall when the form of the heating compartment <NUM> is the cylindrical form as mentioned above, or comprises a plurality of sidewalls when the form of the heating compartment <NUM> differs from the cylindrical form.

The aerosol generating device <NUM> comprises further a heater <NUM> (or a heating arrangement <NUM> or a heating engine <NUM>) for supplying heat to the heating compartment <NUM> to thereby heat the aerosol generating substance <NUM> in the consumable article <NUM> when inserted in the heating compartment. The heater <NUM> is also placed in the housing portion <NUM>. The heater <NUM> may be a heater <NUM> that supplies heat to the heating compartment <NUM> based on a resistive heating, but may also be a heater <NUM> that supplies heat to the heating compartment <NUM> based on inductive heating. The type of heating is not to be seen as limiting to the concept of the present invention.

In this embodiment of the present invention, the heater <NUM> is arranged outside the heating compartment <NUM> so that it indirectly, for example through convective heat transfer, heats the aerosol generating substance <NUM>. <FIG> shows the heater <NUM> as being arranged outside of the heating compartment <NUM> and extending along the first direction (the x-direction) from the base portion <NUM> of the heating compartment <NUM> towards the opening <NUM>. In other words, <FIG> shows the heater <NUM> as extending along a side wall of the heating compartment <NUM>. Further, the heater <NUM> may be arranged outwards of the heating compartment <NUM> on one side of the heating compartment <NUM>, for example closer to the wall of the housing <NUM> or may be arranged on two opposite sides of the heating compartment <NUM> or may be wrapped around the heating compartment <NUM>. In other embodiment of the present invention the heater <NUM> may be arranged at least partially in the heating compartment <NUM> and directly or indirectly heat the aerosol generating substance <NUM>.

The aerosol generating device <NUM> comprises further a detection means <NUM>, <NUM> arranged outside the heating compartment <NUM> and configured to detect whether a consumable article <NUM> has been inserted in the heating compartment <NUM>. The detection means <NUM>, <NUM> are also arranged in the housing portion <NUM>.

The detection means <NUM>, <NUM> comprise at least one hall sensor <NUM> and at least one magnet <NUM>, said hall sensor <NUM> and said magnet <NUM> being arranged outside of the heating compartment <NUM>. <FIG> shows the hall sensor <NUM> and the heating compartment <NUM> as being arranged outwards of the heating compartment <NUM>, on opposite sides of the heating compartment <NUM> in a second direction, denoted in the figure as y-direction, which is perpendicular to the first direction (x-direction). <FIG> shows the hall sensor <NUM> as being arranged closer to the side wall of the housing <NUM> and the magnet <NUM> as being arranged on the opposite side of the heating compartment <NUM> in the second direction, however, the opposite arrangement is also possible, i.e. the magnet <NUM> is arranged closer to the sidewall of the housing <NUM> and the hall sensor <NUM> is arranged on the opposite side of the heating compartment <NUM> in the second direction. Further, <FIG> shows the hall sensor <NUM> and the magnet <NUM> as being arranged close to the base portion <NUM> of the heating compartment <NUM>. However, in a different embodiment of the present invention the hall sensor <NUM> and the magnet <NUM> may be arranged further away from the base position <NUM> and towards the opening <NUM>.

In this embodiment of the present invention the magnet <NUM> is a permanent magnet. In other embodiment of the present invention the magnet <NUM> may be electromagnet, for example a coil which produces electromagnetic field when current is flowing through the coil.

The hall sensor <NUM> may comprise a thin piece of, in general semiconductor material, through which a continuous electrical current is passed to generate a magnetic field. When the hall sensor <NUM> is placed near the magnet <NUM>, the magnetic flux exerts a force on the semiconductor material. This force causes a movement of electrons, creating a measurable hall voltage by the hall sensor.

The output hall voltage from the hall sensor <NUM> is directly proportional to the strength of the magnetic field passing through the semiconductor material of the hall sensor <NUM>.

When the consumable article <NUM> is inserted in the heating compartment, it will weaken the magnetic field from the magnet <NUM> that is detected by the hall sensor <NUM>. In other words, the inserted consumable article <NUM> will act as a shield to the magnetic field of the magnet <NUM> for the hall sensor <NUM> and hence the hall sensor <NUM> will detect a decreased strength of the magnetic field of the magnet <NUM> (drop in the magnetic field). When the consumable article <NUM> comprises thin metal foil as elaborated above it will cause a greater drop in the magnetic field and hence it will be easier for the hall sensor <NUM> to detect the presence of the consumable article <NUM>.

In a different embodiment of the present invention, as shown in <FIG>, the detection means <NUM>, <NUM> may comprise a plurality of hall sensors <NUM> and a plurality of magnets <NUM>. The plurality of hall sensors <NUM> and the plurality of magnets <NUM> are arranged in pairs such that in each pair, the hall sensor <NUM> and the magnet <NUM> are arranged outwards of the heating compartment <NUM> on opposite sides of the heating compartment <NUM> in the second direction which is perpendicular to the first direction. The different pairs are arranged along the first direction from the base portion of the heating compartment <NUM> towards the opening <NUM> of the heating compartment <NUM>.

The aerosol generating device <NUM> comprises further a power supply unit <NUM>. The power supply unit <NUM> is also arranged in the housing portion <NUM>. <FIG> shows the power supply unit <NUM> as being arranged in the lower part of the aerosol generating device <NUM>, however, the position of the power supply unit <NUM> is not to be seen as limiting to the present invention. In other words, in different embodiments of the present invention, the power supply unit <NUM> may be arranged in other parts of the aerosol generating device <NUM> for example sideward from the heating compartment <NUM>. The power supply unit <NUM> may be a battery. The battery may be a rechargeable battery.

The power supply unit <NUM> is configured to supply current to the heater <NUM>. The power supply unit <NUM> is further configured to supply current to the hall sensor <NUM>. In embodiments of the present invention in which the magnet <NUM> is an electromagnet the power supply unit <NUM> is further configured to supply current to the electromagnet.

The aerosol generating device <NUM> comprises further a control unit (not shown in <FIG>) for carrying out various processing as will be elaborated further below. The control unit is further configured for receiving signals as elaborated further below and for activating the supply of current from the power supply unit <NUM> to the heater <NUM> and/or the hall sensor <NUM> and/or the magnet <NUM> in the embodiment of the present invention in which the magnet <NUM> is an electromagnet. The control unit is also arranged in the housing portion <NUM>.

The control unit is any suitable unit or comprises any suitable unit such as computer processing unit that can perform computer processing. The control unit <NUM> (also called controller) may be for example a micro processing unit (MCU). Further, the control unit <NUM> may comprise storage means, such as a memory <NUM>. The memory <NUM> may also be a separate unit from the control unit <NUM> also placed inside the housing portion <NUM>. The memory <NUM> may store different information needed for the processing by the control unit <NUM>, as will be elaborated further below. Further, the memory may store computer program (code) comprising instructions which, when the program is executed by the control unit <NUM>, cause the control unit <NUM> to carry out the processing of the embodiment of the present invention as will be elaborated further below.

<FIG> shows schematically the functional components of the aerosol generating device <NUM> of the embodiment of the present invention arranged in the housing portion <NUM>. More specifically, <FIG> shows the aerosol generating device comprising the heating compartment <NUM>, the heater <NUM>, the detection means <NUM>, the power supply unit <NUM>, the control unit <NUM> and the memory <NUM>. The protection means <NUM>, as elaborated above, are arranged in the access portion <NUM>.

<FIG> show schematically details of detecting the presence of the consumable article <NUM> by the aerosol generating device <NUM> according to the embodiment of the present invention.

<FIG> shows schematically a state of the aerosol generating device <NUM> in which the protection means <NUM> is in the first position, i.e. the opening <NUM> of the heating compartment <NUM> is covered (the protection means <NUM> is closed).

In this state, there is no current flowing through the hall sensor <NUM> so that the hall sensor <NUM> is not detecting the strength of the magnetic field generated by the magnet <NUM>. In other words, the control unit <NUM> has not activated the supply of current from the power supply unit <NUM> to the hall sensor <NUM>. It is noted that even though <FIG> (as well as <FIG>) shows the protection means <NUM> as comprising the slider elaborated above, the elaborations here apply also to the embodiment of the present invention in which the protection means <NUM> comprises the cover lid or a trap door as elaborated above.

When the protection means <NUM> is moved from the first position to the second position so that the opening <NUM> of the heating compartment <NUM> is exposed (the protection means <NUM> is opened) the control unit <NUM> is configured to activate a supply of current from the power supply unit <NUM> to the hall sensor <NUM>. For example, the control unit <NUM> may be configured to activate a supply of current from the power supply unit <NUM> to the hall sensor <NUM> at a time point when the protection means <NUM> reaches the second position by being moved from the first position to the second position or at a pre-determined time after the time point when the protection means <NUM> reaches the second position by being moved from the first position to the second position.

In the embodiment of the present invention the access portion <NUM> of the aerosol generating device may comprise, as elaborated above, sensing means for sensing or determining the position of the protection means <NUM> and the like. When the sensing means senses or detects that the protection means <NUM> has reached the second position by being moved from the first position to the second position the sensing means may send a signal to the control unit <NUM>.

<FIG> shows the aerosol generating device <NUM> in a state in which the protection means <NUM> is in the second position (the protection means is opened). For example, the sensing means my send a signal to the control unit <NUM> at a time point at which the protection means <NUM> has reached the second position by being moved from the first position to the second position or at a pre-determined time after the time point when the protection means <NUM> reaches the second position by being moved from the first position to the second position.

In a different embodiment of the present invention the signal may be sent also in any time point when movement of the protection means <NUM> from the first position towards the second position is sensed or detected by the sensing means.

In response to the receiving of such signal, or in other words, triggered by the receiving of such signal, the control unit <NUM> activates a supply of current from the power supply unit to the hall sensor <NUM>.

Accordingly, the hall sensor <NUM> measures the strength of the magnetic field of the magnet <NUM> when current is passed through the hall sensor <NUM> as elaborated above. The hall sensor <NUM> outputs a value, here below referred to as a first value, indicating said measured strength of the magnetic field to the control unit <NUM>. The control unit <NUM> receives said first value from the hall sensor <NUM> and stores said first value in the memory <NUM>.

The hall sensor <NUM> continuously measures the strength of the magnetic field of the magnet <NUM> while the protection means <NUM> is in the second position and outputs a series of second values indicating the strength of the magnetic field to the control unit <NUM>, each second value indicating the strength of the magnetic field in the corresponding measurement. For example, the hall sensor <NUM> may be arranged to measure the strength of the magnetic field at predetermined time points after the time point at which the measurement for which the first value is obtained is carried out to thereby obtain a second value for each measurement and to output each second value to the control unit <NUM>.

The control unit <NUM> calculates a drop in the magnetic field based on the first value and the second value for each measurement. For example, the control unit <NUM> calculates the drop in the magnetic field by calculating the change from the first value to the second value in terms of percentage decrease. For this, the control unit <NUM> subtracts the second value from the first value to obtain the difference between the first value and the second value, divides the obtained difference between the first value and the second value with the first value and multiplies the result with <NUM> to thereby obtain the percentage decrease of the first value. The control unit <NUM> may also store each received second value and/or each determined percentage decrease in the memory <NUM>.

When the control unit <NUM> detects that the percentage decrease of the first value has reached a pre-determined threshold, or in other words, the percentage decrease of the first value is equal to or higher than a pre-determined threshold (the drop in the magnetic field strength is at least x%, x being a predetermined value), the control unit <NUM> activates a supply of current from the power supply unit <NUM> to the heater <NUM>. The pre-determined threshold may also be pre-stored in the memory <NUM>.

As elaborated above, when the consumable article <NUM> is inserted in the heating compartment <NUM> it will weaken the magnetic field from the magnet <NUM> that is detected by the hall sensor <NUM>. This state of the aerosol generating device is shown schematically in <FIG>. In other word, the inserted consumable article <NUM> acts as a shield to the magnetic field of the magnet <NUM> for the hall sensor <NUM> and therefore the hall sensor <NUM> measures lower strength of the magnetic field (the magnetic field is weakened). As elaborated above, this drop in the magnetic field being at least x% will trigger the control unit <NUM> to turn on the heater <NUM> of the aerosol generating device <NUM> by activating a supply of current from the power supply unit <NUM> to the heater <NUM>.

After the supply of current to the heater <NUM> is activated the hall sensor <NUM> continues with measuring the strength of the magnetic field of the magnet <NUM> and outputting said second value for each measurement to the control unit <NUM> as elaborated above. The control unit <NUM> may continue to determine the drop in the magnetic field of the magnet <NUM> as elaborated above. In this way, the control unit <NUM> may monitor the usage of the consumable article <NUM>. In a different embodiment of the present invention the control unit <NUM> may also cease from determining the drop in the magnetic field after the supply of current to the heater <NUM> is activated.

When the protection means <NUM> is moved again in the first position from the second position, for example as being detected by the above-elaborated sensing means, a signal is sent to the control unit <NUM> by the sensing means. For example, the signal is sent to the control unit <NUM> at the time point when the protection means <NUM> reaches the first position by being moved from the second position to the first position or at a predetermined time after the time point when the protection means <NUM> reaches the first position by being moved from the second position to the first position. In response to receiving said signal the control unit <NUM> turns off the supply of current to the hall sensor <NUM>. Accordingly, the control unit <NUM> is configured to de-activate the supply of current to the hall sensor <NUM> when the protection means <NUM> is moved from the second position to the first position. In addition, the control unit <NUM> may be configured to delete the stored first value and any stored second values and percentage decrease values from the memory <NUM> in response to receiving the signal that the protection means <NUM> is moved in the first position from the second position.

In this way, it is enabled that the heater <NUM> is turned on promptly when the consumable article <NUM> is inserted in the aerosol generating device <NUM>. Accordingly, it is not needed that the user turns on the heater <NUM> after having inserted the consumable article <NUM> manually by operating an operation button or using other means for giving an instruction to the aerosol generating device <NUM> for turning on the heating of the aerosol generating substance. This improves the convenience of the user in using the aerosol generating device <NUM> and even further makes the structure of the aerosol generating device <NUM> less complex since it is not needed that an operation button or other means for giving an instruction to the aerosol generating device for turning on the heating of the aerosol generating substance are provided. Even further, since the detection means, i.e. the hall sensor <NUM> and the magnet <NUM> are arranged outside the heating compartment <NUM> it is enabled that they are protected of being damaged, for example by the user, when cleaning the heating compartment <NUM>.

In summary, in the above-elaborated aerosol generating device <NUM> when it is detected that the consumable article <NUM> has been inserted in the heating compartment <NUM> the heater <NUM> is activated and hence the heating of the aerosol generating substance is started.

Claim 1:
An aerosol generating device (<NUM>) comprising:
a heating compartment (<NUM>) extending along a first direction and comprising a base portion (<NUM>) at a first end and an opening (<NUM>) opposite of the base portion (<NUM>) and arranged so that a user can insert, via the opening (<NUM>), a consumable article (<NUM>) containing an aerosol generating substance (<NUM>);
protection means (<NUM>) for exposing and covering said opening (<NUM>) of the heating compartment (<NUM>),
a heater (<NUM>) configured to supply heat to the heating compartment (<NUM>) to thereby heat the aerosol generating substance (<NUM>) in the consumable article (<NUM>); and
a detection means (<NUM>, <NUM>) arranged outside the heating compartment (<NUM>) and configured to detect whether a consumable article (<NUM>) has been inserted in the heating compartment (<NUM>),
wherein the detection means (<NUM>, <NUM>) comprises at least one hall sensor (<NUM>) and at least one magnet (<NUM>),
characterized in that said hall sensor (<NUM>) and said magnet (<NUM>) are arranged outwards of the heating compartment (<NUM>) on opposite sides of the heating compartment (<NUM>) in a second direction which is perpendicular to the first direction.