Aerosol-generating device for heating aerosol-forming substrate

Abstract

The present disclosure relates to an aerosol-generating device for heating an aerosol-forming substrate, the aerosol-generating device comprising a device housing having a cavity for removably receiving at least a portion of an aerosol-generating article, the aerosol-generating article includes an aerosol-forming substrate and an inductively heatable susceptor for heating the substrate. Further, the apparatus includes an induction heating device configured to generate an alternating magnetic field within the cavity for inductively heating a susceptor of the article when the article is received in the cavity. Further, the device includes a closure detector arranged and configured to detect at least one of when a closure of the device is in an open position, when the closure covers an insertion opening of the cavity in the open position, or when the closure moves from a closed position to an open position, when the closure covers the insertion opening of the cavity in the open position. In the closed position, the insertion opening is not blocked by the closure. The device also includes control circuitry operably connected to the induction heating device and to the closure detector, the closing member is coupled to the closing detector and is configured to energize the induction heating device in response to signals from the closing detector indicating that the closing member is in the open position or moves from the closed position to the open position, respectively; determining at least one characteristic or a change in at least one characteristic of the induction heating device during energization of the induction heating device, the at least one characteristic depending on at least one of a type of the susceptor, a presence, absence, position or movement of the susceptor in the cavity; and detecting at least one specific state associated with the article based on the determined characteristic of the induction heating device or a change in the determined characteristic. The invention also relates to an aerosol-generating system comprising such a device and an aerosol-generating article.

Description

[0001] The present invention relates to an aerosol generating device comprising a cavity for removably receiving at least a portion of an aerosol generating article, wherein the article comprises a susceptor and an aerosol-forming substrate to be heated by the interaction of the susceptor with an alternating magnetic field generated by the device. The present invention also relates to an aerosol generating system comprising such a device and an aerosol generating article.

[0002] Aerosol generating devices for heating an aerosol-forming substrate capable of forming an inhalable aerosol when heated are generally known in the prior art. Such devices may comprise a cavity for removably receiving at least a portion of an aerosol-generating article comprising an aerosol-forming substrate to be heated. For heating the substrate, the device may further comprise an induction heating device configured to generate an alternating magnetic field within the cavity for inductively heating a susceptor that is part of the article and is arranged in thermal proximity or direct physical contact with the substrate to be heated.

[0003] For various purposes, such devices may also include means for detecting one or more specific conditions related to the article based on the determined characteristics or changes in the determined characteristics of the induction heating device. For example, such devices may detect the insertion of the article into the cavity or the type of article inserted into the cavity. Using a heating device to detect such conditions generally requires that the heating device be powered. This is associated with additional power consumption, which in turn can significantly reduce the operating time of the device.

[0004] It would therefore be desirable to have an aerosol generating device having the advantages of prior art solutions whilst alleviating their limitations. In particular, it would be desirable to have an aerosol generating device using a heating device to detect one or more specific conditions associated with an article which is improved over prior art solutions.

[0005] According to the present invention, there is provided an aerosol generating device for heating an aerosol-forming substrate capable of forming an inhalable aerosol when heated. The device comprises a device housing comprising a cavity for removably receiving at least a portion of an aerosol-generating article, wherein the article comprises the aerosol-forming substrate and an inductively heatable susceptor for heating the substrate. The cavity comprises an insertion opening for inserting the article into the cavity. The device further comprises a closure member, the closure member being reversibly movable relative to the device housing between a closed position and an open position, wherein the closure member covers the insertion opening, and wherein the insertion opening is not blocked by the closure member. In addition, the device comprises an inductive heating device, the inductive heating device being configured to generate an alternating magnetic field in the cavity for inductively heating the susceptor of the article when the article is received in the cavity. In addition, the device comprises a closure detector, the closure detector being arranged and configured to detect at least one of the following: when the closure member is in the open position or when the closure member moves from the closed position to the open position. The device also includes a control circuit system operably connected to the induction heating device and the closure detector and configured to

[0006] - energizing the induction heating device in response to a signal from the closure detector indicating that the closure element is in the open position or has moved from the closed position to the open position, respectively;

[0007] - determining at least one characteristic of the induction heating device or a change in at least one characteristic during energization of the induction heating device, the at least one characteristic being dependent on at least one of the type of the susceptor, the presence, absence, position or movement of the susceptor in the cavity; and - detecting at least one specific state related to the product based on the determined characteristic or the change in the determined characteristic of the induction heating device.

[0008] Such a specific state may be one of the type of article, the insertion of an article, the presence, absence, position or displacement of an article in the cavity. Thus, the control circuit system may be configured to detect at least one of the type of article, the insertion of an article, the presence, absence, position and displacement of an article in the cavity based on the determined characteristic or the change in the determined characteristic of the induction heating device.

[0009] According to the invention, the state detection is based on the fact that a specific article type, insertion, presence, withdrawal and / or absence of an article influences or modifies at least one property, in particular at least one electrical and / or magnetic property of the induction heating device. This is due to a field-induced interaction between the induction heating device and the susceptor, the influence of which on the property or the change of said at least one property depends on the specific property of the susceptor (susceptor type), on the presence or absence of the susceptor in the cavity and on the movement and actual position of the susceptor relative to the induction heating device, in particular relative to the inductor of the induction heating device.

[0010] The at least one characteristic of the induction heating device may be any characteristic having an associated parameter that depends on at least one of the type of susceptor, the presence, absence, position and movement of the susceptor in the cavity. For example, the at least one characteristic may be a characteristic having an associated parameter that has a different value when the susceptor is present than when the susceptor is absent. For example, the at least one characteristic may be current, voltage, resistance, frequency, phase shift, magnetic flux and inductance of the induction heating device.

[0011] Preferably, the at least one characteristic or the change in at least one characteristic determined by the control circuitry is the current or the change in current supplied to the induction heating device.

[0012] Likewise, at least one characteristic or a change in at least one characteristic may be at least one of an equivalent resistance or inductance of the induction heating device or a change in the equivalent resistance or inductance of the induction heating device, respectively. As used herein, the term "equivalent resistance" refers to the real part of a complex impedance, which is defined as the ratio of the AC voltage supplied to the induction heating device to the measured AC current. Therefore, the "equivalent resistance" may also be expressed as a resistive load of the induction heating device. Likewise, as used herein, the term "inductance" refers to the imaginary part of a complex impedance, which is defined as the ratio of the supplied AC voltage to the measured AC current. Generally speaking, inductance has a circuit characteristic that is susceptible to external electromagnetic influences.

[0013] A specific value of at least one characteristic or a change in at least one characteristic of the induction heating device may be attributed to a specific magnetic permeability and / or a specific resistivity of the susceptor. That is, the susceptor in the aerosol-generating article may include a material having a specific magnetic permeability and / or a specific resistivity. Preferably, the susceptor includes a conductive material. For example, the susceptor may include a metallic material. The metallic material may be, for example, one of aluminum, nickel, iron, or an alloy thereof, such as carbon steel or ferritic stainless steel. Aluminum has a resistivity of about 2.65×10E-08 ohm-meters and a magnetic permeability of about 1.256×10E-06 Henry / meter measured at room temperature (20°C). Similarly, ferritic stainless steel has a resistivity of about 6.9×10E-07 ohm-meters and a magnetic permeability in the range of 1.26×10E-03 Henry / meter to 2.26×10E-03 Henry / meter measured at room temperature (20°C).

[0014] According to the present invention, it has been found that any state detection involving the heating device consumes the least amount of energy if it is actively powered on only when the state detection is actually required. In addition, it has been found that many of the aforementioned states will be detected at the beginning of the user experience shortly before the actual heating operation of the device, that is, when the heating device is not actually functional yet but is about to be used. With this in mind, it has been concluded that for a device with a movable closure to reversibly cover and release the insertion opening of the cavity, the opening of the closure can be a very suitable indication of the beginning of the user experience, and can therefore be a very suitable trigger for starting state detection. Therefore, the present invention proposes to detect when the closure of the cavity is in the open position, or when the closure moves from the closed position to the open position, and then start the state detection (by powering the induction heating device) only in response to a signal indicating that the closure is in the open position or moves from the closed position to the open position, respectively.

[0015] Advantageously, using the opening of the closure as a trigger does not require any additional user interaction with the device, such as pressing a button. Instead, this trigger advantageously exploits an action taken by the user at the beginning of the user experience, i.e. enabling the insertion of the aerosol-generating article into the cavity.

[0016] Furthermore, the use of an induction heating device not only for heating purposes but also for state detection advantageously enables additional assembly space for a separate sensor device to be avoided.

[0017] While the opening of the closure may be a very suitable indication of the beginning of the user experience, the closing of the closure may be a very suitable indication of the end of the user experience and may therefore be a very suitable trigger to stop energizing the induction heating device. Therefore, the closure detector may be arranged and configured to further detect at least one of the following: when the closure is in the closed position or when the closure moves from the open position to the closed position. Therefore, the control circuit system may be configured to stop energizing the induction heating device in response to a signal from the closure detector indicating that the closure is in the closed position or when the closure moves from the open position to the closed position, respectively.

[0018] In particular, the closure detector may be configured to detect both the opening of the closure and the closing of the closure. Thus, the closure detector may be configured to detect at least one of when the closure is in the open position or when the closure moves from the closed position to the open position, and at least one of when the closure is in the closed position or when the closure moves from the open position to the closed position. More specifically, the closure detector may include a first closure detector configured to detect at least one of when the closure is in the open position or when the closure moves from the closed position to the open position, and a second detector separate from the first closure detector, configured to detect at least one of when the closure is in the closed position or when the closure moves from the open position to the closed position.

[0019] In general, the closure detector may be any detector that can reliably detect the position and / or movement of the closure member. For example, the closure detector may include or may be one of a magnetic closure detector, an optical closure sensor, a capacitive closure detector, an inductive closure detector, and an electromechanical switch.

[0020] In case the closure detector is or comprises a magnetic closure detector, the magnetic closure detector may comprise at least one magnetic sensor fixedly arranged in the housing of the device and at least one associated permanent magnet attached to the closure, such that the magnetic sensor senses the magnetic field of the associated permanent magnet when the closure is in the open position or moves into the open position, in particular only when the closure is in the open position. In particular, the permanent magnet and the magnetic sensor may be arranged such that the magnetic sensor senses the magnetic field of the associated permanent magnet only when the closure is in the open position.

[0021] Alternatively, the magnetic closure detector may comprise at least one magnetic sensor fixedly arranged in the device housing and at least one associated permanent magnet attached to the closure element, such that the magnetic sensor senses the magnetic field of the associated permanent magnet when the closure element is in the closed position or moves to the closed position, and in particular only when the closure element is in the closed position.

[0022] According to another alternative, the magnetic closure detector may include at least one permanent magnet, which is attached to the closure or arranged at / in the closure; and at least two magnetic sensors, which are fixedly arranged in the device housing, so that one of the magnetic sensors (in particular the first magnetic sensor) senses the magnetic field of the permanent magnet when the closure is in an open position or moves to an open position, in particular only when the closure is in the open position, and the other of the magnetic sensors (in particular the second magnetic sensor) senses the magnetic field of the permanent magnet when the closure is in a closed position or moves to a closed position, in particular only when the closure is in a closed position.

[0023] According to yet another alternative, the magnetic closure detector may include at least two permanent magnets attached to the closure or arranged at / in the closure and at least two magnetic sensors fixedly arranged in the device housing, so that one of the magnetic sensors (in particular the first magnetic sensor) senses the magnetic field of one of the permanent magnets (in particular the first permanent magnet) when the closure is in an open position or moves to an open position, in particular only when the closure is in the open position, and the other of the magnetic sensors (in particular the second magnetic sensor) senses the magnetic field of the other of the permanent magnets (in particular the second permanent magnet) when the closure is in a closed position or moves to a closed position, in particular only when the closure is in a closed position.

[0024] Advantageously, each of the aforementioned arrangements ensures that the opening or closing of the closure element can be detected reliably, in particular without external interference.

[0025] In order to ensure an undisturbed detection of the opening movement or the open position of the closure, the respective magnetic sensor for detecting the opening movement or the open position of the closure can be arranged at a distance of at most 3 mm, in particular at most 2.5 mm, next to the associated permanent magnet when the closure is in the open position. In addition, the respective magnetic sensor for detecting the opening movement or the open position of the closure can be at least 5 mm, in particular at least 7.5 mm, preferably at least 10 mm, more preferably at least 15 mm from the associated permanent magnet when the closure is in the closed position.

[0026] Likewise, in order to ensure an interference-free detection of the closing movement or the closed position of the closure, the respective magnetic sensor for detecting the closing movement or the closed position of the closure can be arranged at a distance of at most 3 mm, in particular at most 2.5 mm, next to the associated permanent magnet when the closure is in the open position. In addition, the respective magnetic sensor for detecting the closing movement or the closed position of the closure can be at least 5 mm, in particular at least 7.5 mm, preferably at least 10 mm, more preferably at least 15 mm from the associated permanent magnet when the closure is in the open position.

[0027] Preferably, the magnetic sensors used in the various configurations discussed previously may be Hall sensors.

[0028] In the case where the closure detector is an optical closure detector or includes an optical closure detector, the optical closure detector may include a light sensor for detecting light, in particular ambient light. The light sensor is preferably arranged so that it is at least partially covered by the closure or a cover attached to / arranged at the closure when the closure is in the open position or in the closed position, respectively, and is not blocked by the closure or a cover attached to / arranged at the closure when the closure is in the closed position or in the open position. In this configuration, the closure or the cover attached to / arranged at the closure is advantageously used as a light gate in front of the light sensor, which switches between a light transmission state and a light blocking state by the movement of the closure. Therefore, when the light sensor detects any light or light above a predefined intensity threshold, the light sensor can generate a first signal indicating that the closure is in the open position, and in addition, when the light sensor does not detect light or only detects light below the predefined intensity threshold, a second signal indicating that the closure is in the closed position is generated. Preferably, the light to be detected by the light sensor is ambient light. Therefore, no additional light source is required, which keeps the technical workload low.

[0029] As an alternative, the optical closure detector can be configured as a light barrier. To this end, the optical closure detector may include a light emitter and a light receiver for sensing light emitted from the light emitter. The light emitter and the light receiver may be arranged so that light emitted from the light emitter toward the light receiver is blocked by the closure or a cover attached to / arranged at the closure when the closure is in an open position, and is not blocked by the closure or a cover attached to / arranged at the closure when the closure is in a closed position. Similarly, the light emitter and the light receiver may be arranged so that light emitted from the light emitter toward the light receiver is blocked by the closure or a cover attached to / arranged at the closure when the closure is in a closed position, and is not blocked by the closure or a cover attached to / arranged at the closure when the closure is in an open position. Advantageously, by using a light barrier with an internal light emitter, closure detection is independent of ambient light and therefore works under all lighting conditions, whether outdoors or indoors, and whether during the day or at night.

[0030] In the case where the closure detector is an electromechanical switch or includes an electromechanical switch, the electromechanical switch can be activated by the closure or an actuator attached to / arranged at the closure when the closure is in the open position or in the closed position, respectively, and deactivated by the closure or an actuator attached to / arranged at the closure when the closure is in the closed position or in the open position.

[0031] Alternatively or in addition, the electromechanical switch may be activated by the closure or an actuator attached to / arranged at the closure when the closure moves from the open position to the closed position or from the closed position to the open position. Likewise, the electromechanical switch may be deactivated by the closure or an actuator attached to / arranged at the closure when the closure moves from the closed position to the open position or from the open position to the closed position.

[0032] The closure detector may also include two electromechanical switches, wherein one of the electromechanical switches can be activated by the closure or an actuator attached to / arranged at the closure when the closure is in the open position or moves to the open position, and wherein the other of the electromechanical switches can be activated by the closure, or the same actuator attached to / arranged at the closure, or another actuator attached to / arranged at the closure, when the closure is in the closed position or moves to the closed position.

[0033] In any of these configurations of the electromechanical switch, the actuator attached to / arranged at the closure may be a mechanical pusher or snap, etc. Similarly, the closure itself or a portion of the closure may be used as a mechanical pusher or snap, etc. As used herein, the term "electromechanical switch" refers to a mechanically driven electrical component that can disconnect or connect a conductive path in a circuit, interrupting current or diverting it from one conductor to another. In particular, the electromechanical switch may include one or more sets of movable electrical contacts connected to an external circuit. Thus, the switch facilitates the generation of at least two signals, one signal indicating that the switch is activated and the other signal indicating that the switch is deactivated.

[0034] In general, the closure may be of any type suitable for opening and closing the insertion opening of the cavity.

[0035] According to a first embodiment, the closure may be a sliding closure that is slidably guided on the device housing between the open position and the closed position. For example, the sliding closure may be slidably guided on the device housing by means of one or more guide rails, in particular one or more pairs of corresponding guide rails, wherein one of such a pair of guide rails is arranged at the closure and the corresponding other guide rails of the pair of guide rails are arranged at the device housing. Likewise, the sliding closure may be slidably guided on the device housing by means of one or more guide grooves and correspondingly formed guide members, the correspondingly formed guide members being slidably guided in the guide grooves in a form-fitting manner. For example, the closure may include one or more guide members, each of which is slidably guided in a form-fitting manner in a correspondingly formed guide groove on the device housing. Vice versa, one or more guide members may be arranged on the device, each of which is slidably guided in a correspondingly formed guide groove on the closure.

[0036] According to a second embodiment, the closure may be a pivoting closure pivotally mounted to the device housing. To this end, the aerosol generating device may comprise a pivoting mechanism, such as one or more hinges or one or more pivoting arms, which pivotably couples the closure to the device housing.

[0037] According to a third embodiment, the closure element may be an iris diaphragm closure element.

[0038] At least one characteristic of the induction heating device or a change in at least one characteristic can be observed by measuring a change in a parameter of the induction heating device. The parameter can be measured directly or indirectly. For example, the presence or absence of an article can be determined by measuring the parameter and observing that the parameter has a different value when the article is present, i.e., when the susceptor is present, than when the article is not present, i.e., when the susceptor is absent.

[0039] Preferably, the parameter may be a current. Likewise, the current may be a characteristic itself determined by the control circuit system. In particular, at least one characteristic or a change in at least one characteristic determined by the control circuit system may be a current or a change in current supplied to the induction heating device. Thus, the control circuit system may be configured to detect the presence of a susceptor in the cavity when (or in response to) the current or a change in current supplied to the induction heating device violates or reaches a threshold, for example when the current or the change in current exceeds or falls below a threshold.

[0040] In the case where the characteristic or parameter indicating the characteristic is a current, the control circuit system may include a measuring device for measuring a current corresponding to or indicating at least one characteristic or a change in at least one characteristic of the induction heating device. The characteristic or parameter indicating the characteristic may be a current supplied from the power supply of the device, in particular a DC current supplied from the DC power supply of the device to the induction heating device. Therefore, the control circuit system may include a measuring device, which is arranged and configured to measure the current supplied from the power supply of the device to the induction heating device, in particular a DC current supplied from the DC power supply of the device. The measuring device may include a current measuring device, in particular a DC current measuring device, which is arranged in series connection between the power supply of the device, in particular the DC power supply and the induction heating device. For example, the measuring device may include a resistor and a shunt amplifier. In use, when the aerosol generating article is inserted into the cavity of the aerosol generating device, the susceptor is present in the cavity or becomes present in the cavity due to the increase in resistive load, increasing the equivalent resistance. This in turn reduces the (DC) current feeding the induction heating device. The reduction in the (DC) current is detected by the current measuring device of the control circuit system, which may then activate the heating operation of the induction heating device for heating the substrate. Vice versa, when no aerosol-generating article is present in the cavity, the equivalent resistance is lower due to the lower resistive load in the absence of the susceptor. This in turn involves a higher (DC) current fed to the inductive heating device, which can be detected by the current measuring means of the control circuit system, thus indicating the absence of the article in the cavity. Likewise, when the aerosol-generating article is displaced within the cavity, the equivalent resistance may change to a higher or lower value due to a corresponding change in the resistive load, which is related to the actual position of the susceptor relative to the heating device, in particular the inductor of the heating device. The change in the resistive load causes a change in the (DC) current fed to the inductive heating device, which again can be detected by the current measuring means, thus indicating a displacement or a specific position of the article within the cavity.

[0041] In order to further reduce the power consumption compared to other solutions, and therefore to further increase the overall operating time of the device, the induction heating device may be operated in a pulsed mode for the purpose of state detection. Therefore, the control circuit system may be configured to generate power pulses for intermittently, in particular periodically, powering up the induction heating device, and determining the at least one characteristic of the induction heating device or a change in the at least one characteristic during one or more power pulses. In order to generate this power pulse, the control circuit system may include a switch, which is configured and arranged to control the power supply to the induction heating device from a power supply of the device, in particular a DC power supply. The switch may be intermittently closed and opened in order to intermittently power up the induction heating device in order to allow detection of at least one specific state related to the article based on the determined characteristic or the change in the determined characteristic of the induction heating device.

[0042] Depending on the particular state detected by the control circuitry, the control circuitry may be configured to take further action, in particular to initiate, enable or disable various operating modes, such as heating operation.

[0043] Preferably, the control circuit system is configured to initiate the heating operation of the induction heating device in response to detecting the insertion of the article into the cavity. Advantageously, this enhances the convenience for the user, as the heating operation automatically starts when the article is inserted into the cavity, without requiring any further user input. In particular, the user experience starts immediately as known from a conventional cigarette. Additionally or alternatively, the heating operation of the induction heating device may also be activated manually, i.e. by user input, such as by pressing a button.

[0044] The control circuit system may also be configured to disable the heating operation of the induction heating device in response to detecting at least one of the absence of an article in the cavity, the displacement of the article in the cavity, or an inappropriate article type that has been inserted into the cavity. Advantageously, this prevents the user of the device from starting the heating operation when no article is present in the cavity, or when the article is not properly placed in the cavity or is an inappropriate article type. Thus, damage and malfunction of the device may be effectively prevented.

[0045] The control circuitry may also be configured to stop the heating operation of the device subject to various conditions. Specifically, the control circuitry may be configured to stop the heating operation of the device in response to at least one of detecting a predetermined number of puffs, detecting that a predetermined heating time has elapsed, or receiving user input.

[0046] The control circuit system can also be configured to verify that the article is inserted into the cavity or that there is no article in the cavity by energizing the induction heating device, in particular by generating at least one verification power pulse within a predetermined time period after the specific value of the corresponding characteristic of the induction heating device or the specific change of the corresponding characteristic is detected for the first time, and by re-detecting the specific value or change of the corresponding characteristic of the induction heating device.

[0047] In the case where the control circuit system is configured to energize the induction heating device in a pulsed mode by generating power pulses for intermittently energizing the induction heating device, the control circuit system may include a switch configured and arranged to control the power supply from the power supply of the device, in particular a DC power supply, to the induction heating device. To this end, the switch may be intermittently closed and opened in order to intermittently energize the induction heating device.

[0048] The generation of power pulses can also be used to achieve pulsed heating operation, in which the induction heating device is intermittently powered on and off to heat the susceptor in a pulsed mode. The previously mentioned switches of the control circuit system can also be used for this purpose. In particular, the heating mode can include pulse width modulation of the heating power pulses for controlling the heating temperature.

[0049] It is also possible that during the heating operation of the device, the switch may be permanently closed to continuously apply the DC voltage of the DC power supply to the induction heating device. Therefore, this mode can be denoted as continuous heating operation.

[0050] During heating operation, the control circuitry may also be capable of detecting withdrawal of the article from the cavity by detecting a change in at least one characteristic of the induction heating device due to the absence of the susceptor in the cavity when the aerosol-generating article is withdrawn from the cavity.

[0051] Generating a power pulse for detecting at least one specific state associated with the article may be denoted as a detection power pulse. Thus, the control circuit system may be configured to generate a detection power pulse. Similarly, a power pulse generated for heating a susceptor in a pulsed mode may be denoted as a heating power pulse. Thus, the control circuit system may be configured to generate a heating power pulse.

[0052] In general, the probing power pulse and the heating power pulse may be identical. It is also possible that the probing power pulse and the heating power pulse may differ from each other in at least one characteristic of the power pulse, in particular in at least one of the pulse pattern, the amplitude of the power pulse, the pulse duration and the time interval between two consecutive power pulses. In particular, the amplitude of the heating power pulse may be greater than the amplitude of the probing power pulse. In addition, the probing power pulse may have a fixed pulse pattern, in particular a fixed period. In contrast, the heating power pulse may have a non-fixed, in particular a variable pulse pattern, for example in order to achieve a pulse width modulation of the heating power.

[0053] In general, the pulse duration and the time interval between two consecutive power pulses, in particular the detection power pulses, should be selected so as to balance the impact of energy consumption and user experience performance. The pulse duration should be as short as possible, but still long enough to provide a reliable measurement of at least one characteristic or a change in at least one characteristic of the induction heating device. Likewise, the higher the time interval between two consecutive power pulses, in particular the detection power pulses, the lower the energy consumption. However, the time interval between two consecutive power pulses, in particular the detection power pulses, should not be too long, otherwise the state detection may be too time-consuming.

[0054] Taking these factors into account, the power pulse, in particular the detection power pulse, may have a pulse duration in the range of 1 microsecond to 500 microseconds, in particular between 10 microseconds and 300 microseconds, preferably between 15 microseconds and 120 microseconds, and most preferably between 30 microseconds and 10 microseconds. As used herein, the term "pulse duration" means the time interval during which the heating device is powered on, in particular the time interval during which the above-mentioned switch is closed. The time interval between two consecutive power pulses, in particular the detection power pulse, may be in the range of 50 milliseconds to 2 seconds, in particular between 100 milliseconds and 2 seconds, preferably between 500 milliseconds and 1 second. The sum of the pulse duration and the time interval between two consecutive power pulses may be expressed as the polling time, i.e. the time difference between the start of a pulse and the start of the next pulse. The polling time may be in the range of 50 milliseconds to 2.5 seconds, in particular between 51 milliseconds and 2.5 milliseconds, more specifically between 100 milliseconds and 2 seconds, preferably between 500 milliseconds and 1 second.

[0055] Preferably, the power pulses for state detection, in particular the detection power pulses, are generated within a predetermined time period. That is, the state detection may last for a limited predetermined time period. In case a specific state, such as the insertion of an article into the cavity, is not detected within the predetermined time period, the state detection may be stopped, i.e. the generation of the power pulses may be switched off for safe use of the power, as described above. Likewise, in case a specific state is detected within the predetermined time period, the state detection and thus the generation of the power pulses may be stopped, in particular immediately stopped, in response to the detection of the specific state.

[0056] The induction heating device can be configured to generate a high-frequency alternating magnetic field. As mentioned herein, the high-frequency alternating magnetic field can range between 500kHz (kilohertz) and 30MHz (megahertz), particularly between 5MHz (megahertz) and 15MHz (megahertz), preferably between 5MHz (megahertz) and 10MHz (megahertz).

[0057] In order to generate an alternating magnetic field, the induction heating device may include a DC / AC converter connected to a DC power supply. The DC / AC converter may include an LC network. For example, the DC / AC converter may include a class C power amplifier or a class D power amplifier or a class E power amplifier. In particular, the DC / AC converter may include a transistor switch and a transistor switch drive circuit and an LC network. The LC network may include a series connection of a capacitor and an inductor, and wherein the inductor is configured and arranged to generate an alternating magnetic field in the cavity, particularly for inductively heating the susceptor and for product detection. The LC network may also include a shunt capacitor in parallel with the transistor switch. In addition, the DC / AC converter may include a choke inductor for supplying a DC power supply voltage +V_DC from a DC power supply.

[0058] The inductor for generating an alternating magnetic field in the cavity may comprise at least one induction coil, in particular a single induction coil or a plurality of induction coils. The number of induction coils may depend on the size and / or number of the receptors. One or several induction coils may have a shape that matches the shape of one or more receptors in the aerosol generating article. Similarly, one or several induction coils may have a shape that conforms to the shape of the housing of the aerosol generating device. At least one induction coil may be a spiral coil or a planar coil, in particular a pancake coil or a curved planar coil. At least one induction coil may be wound around a preferably cylindrical coil support, such as a ferrite core.

[0059] The control circuitry may also be configured to control the overall operation of the aerosol generating device.The control circuitry and at least part of the inductive heating device may be integral parts of the overall circuitry of the aerosol generating device.

[0060] The control circuit system may include a microprocessor, such as a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuit system capable of providing control. The microprocessor may be configured to perform at least one of the following: controlling a switch for generating power pulses for intermittently powering up the induction heating device, reading a measuring device for measuring the current supplied from the power supply to the induction heating device (if present), and controlling a transistor switch driver circuit of the induction heating device (if present).

[0061] The control circuit system may be or may be part of the overall controller of the aerosol generating device. The controller and at least part of the inductive source, in particular an inductive source other than an inductor, may be arranged on a common printed circuit board. This has proven to be particularly advantageous with regard to a compact design of the heating device.

[0062] Preferably, the aerosol generating device is a suction device for generating an aerosol which can be inhaled directly by a user through the user's mouth. In particular, the aerosol generating device is a handheld aerosol generating device.

[0063] As previously mentioned, the aerosol generating device preferably comprises a power source, in particular a DC power source, such as a battery. The power source may need to be charged, that is, the power source may be rechargeable. The power source may have a capacity that allows sufficient energy to be stored for one or more user experiences. For example, the power source may have sufficient capacity to allow continuous generation of aerosol for a period of about six minutes or a multiple of six minutes. In another example, the power source may have sufficient capacity to allow a predetermined number of puffs or discontinuous activation of the induction source.

[0064] As used herein, the direction in which the aerosol generating article is inserted into the cavity is indicated as the insertion direction. Preferably, the insertion direction corresponds to the extension of the length axis, in particular the extension of the central axis of the cavity. After being inserted into the cavity, at least a portion of the aerosol generating article can still extend outwardly through the insertion opening. The outwardly extending portion is preferably provided for interaction with the user, in particular to be placed in the user's mouth. Therefore, during use of the device, the insertion opening can be close to the user's mouth. Therefore, as used herein, when using the device, the section close to the insertion opening or close to the user's mouth is respectively indicated by the prefix "proximal". The section arranged further away is indicated by the prefix "distal". Relative to this convention, the cavity can be arranged in or located in the proximal part of the aerosol generating device. The insertion opening can be arranged or located at the proximal end of the aerosol generating device, in particular at the proximal end of the cavity. At the distal end, the cavity may include a bottom opposite to the insertion opening.

[0065] The aerosol generating device may include an air path extending from at least one air inlet into the cavity. That is, the aerosol generating device may include at least one air inlet in fluid communication with the cavity. When the aerosol generating article is inserted into the cavity, the air path may further extend through the aerosol-forming substrate within the article and the mouthpiece of the article to enter the mouth of the user. Preferably, the air inlet is implemented at an insertion opening of the cavity for inserting the article into the cavity. Therefore, when the article is received in the cavity, air can be drawn into the cavity at the edge of the insertion opening and can further pass through an airflow path formed between the periphery of the aerosol generating article and at least one or more portions of the inner surface of the cavity.

[0066] In general, the cavity may have any suitable shape. In particular, the shape of the cavity may correspond to the shape of the aerosol generating article to be received therein. Preferably, the cavity may have a substantially cylindrical shape or a conical shape, for example a substantially conical shape or a substantially frustoconical shape. The cavity may have any suitable cross-section, as seen in a plane perpendicular to the length axis of the cavity or perpendicular to the insertion direction of the article. In particular, the cross-section of the cavity may correspond to the shape of the aerosol generating article to be received therein. Preferably, the cavity has a substantially circular cross-section. Alternatively, the cavity may have a substantially elliptical cross-section or a substantially oval cross-section or a substantially square cross-section or a substantially rectangular cross-section or a substantially triangular cross-section or a substantially polygonal cross-section. As used herein, the above shapes and cross-sections preferably refer to the shape or cross-section of the cavity, without taking into account any protrusions at the inner surface of the cavity.

[0067] The inductor may be arranged so as to surround at least a portion of the cavity or at least a portion of the inner surface of the cavity, respectively. For example, the inductor may be a spiral coil arranged within the side wall of the cavity. Specifically, the inductor may be integrated into the wall defining the cavity. For example, the inductor may be integrated into the side wall of the cavity, in particular, so as to surround at least a portion of the interior of the cavity.

[0068] The cavity may include a plurality of protrusions extending in the interior of the cavity. Preferably, the protrusions are spaced apart from each other so that an airflow path is formed between adjacent protrusions, i.e., through the gaps (free spaces) between adjacent protrusions. In addition, the plurality of protrusions may be configured to contact at least a portion of the aerosol generating article to hold the aerosol generating article in the cavity. The plurality of protrusions may include or may be formed as ribs. Preferably, one or more ribs extend along the length axis of the cavity, in particular in the direction of the central axis.

[0069] The present invention also relates to an aerosol generating system, comprising an aerosol generating device according to any of the preceding claims and an aerosol generating article for use with the aerosol generating device, wherein the aerosol generating article is removably receivable in a cavity of the device and comprises at least one aerosol-forming substrate and at least one inductively heatable susceptor, wherein the at least one inductively heatable susceptor is used to heat the substrate by interaction between the susceptor and an alternating magnetic field provided by an inductive heating device of the device.

[0070] As used herein, the term "aerosol-generating article" refers to an article comprising at least one aerosol-forming substrate which, when heated, releases volatile compounds that can form an aerosol. Thus, an aerosol-generating article may be denoted a heated aerosol-generating article or an aerosol-generating article for heating. That is, the aerosol-generating article preferably comprises at least one aerosol-forming substrate which is intended to be heated rather than burned in order to release volatile compounds that can form an aerosol. The aerosol-generating article may be a consumable, in particular a consumable that is disposed of after a single use.

[0071] As used herein, the term "aerosol formation substrate" relates to a substrate that can release a volatile compound that can form an aerosol when heated.Aerosol formation substrate can be a solid aerosol formation substrate or a gel-like aerosol formation substrate or a liquid aerosol formation substrate or a combination thereof.Aerosol formation substrate can include a tobacco-containing material, and the tobacco-containing material contains volatile tobacco flavor compounds released from the substrate when heated.Alternatively or additionally, aerosol formation substrate can include non-tobacco material.Aerosol formation substrate can also include an aerosol former. The example of a suitable aerosol former is glycerol and propylene glycol.Aerosol formation substrate can also include other additives and ingredients, such as nicotine or flavoring substances.Specifically, liquid aerosol formation substrate can include water, solvent, ethanol, plant extract and natural or artificial flavoring agent. The aerosol-forming substrate may also be a paste-like material, a pouch of porous material comprising the aerosol-forming substrate, or for example loose tobacco mixed with a gelling or sticking agent, which may include common aerosol formers such as glycerol, and then compressed or moulded into a rod.

[0072] The aerosol-generating article may be a tobacco product. In particular, the article may be a rod-shaped article, preferably a cylindrical rod-shaped article, which may be similar to a conventional cigarette. The aerosol-generating article may have a circular, elliptical, oval, square, rectangular, triangular or polygonal cross-section.

[0073] For example, the aerosol-generating article may be a rod-shaped article. In particular, the cylindrical article comprises one or more of the following elements: a distal front-rod element, a matrix element, a first tube element, a second tube element and a filter element.

[0074] The substrate element preferably comprises at least one aerosol-forming substrate to be heated and a susceptor in thermal contact or thermal proximity to the aerosol-forming substrate.The substrate element may have a length of 10 mm to 14 mm, for example 12 mm.

[0075] As used herein, the term "susceptor" refers to an element comprising a material capable of being inductively heated within an alternating magnetic field. This may be the result of at least one of hysteresis losses or eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.

[0076] The first tube element is more distal than the second tube element. Preferably, the first tube element is proximal to the matrix element, while the second tube element is proximal to the first tube element and distal to the filter element, i.e., between the first tube element and the filter element. At least one of the first tube element and the second tube element may include a central air passage. The cross-section of the central air passage of the second tube element may be greater than the cross-section of the central air passage of the first tube element. Preferably, at least one of the first tube element and the second tube element may include a hollow cellulose acetate tube. At least one of the first tube element and the second tube element may have a length of 6 mm to 10 mm (e.g., 8 mm).

[0077] The filter element is preferably used as a mouthpiece, or as part of a mouthpiece together with the second tube element. As used herein, the term "mouthpiece" refers to the part of the article through which the aerosol leaves the aerosol generating article. The filter element may have a length of 10 mm to 14 mm, for example 12 mm.

[0078] The distal front rod element can be used to cover and protect the distal front end of the matrix element. The distal front rod element can have a length of 3 mm to 6 mm (e.g., 5 mm). The distal front rod element can be made of the same material as the filter element.

[0079] All the aforementioned elements can be arranged in sequence along the length axis of the article in the above order, wherein the distal front rod element is preferably arranged at the distal end of the article, and the filter element is preferably arranged at the proximal end of the article. Each of the aforementioned elements can be substantially cylindrical. In particular, all elements can have the same outer cross-sectional shape and / or size.

[0080] In addition, these elements can be limited by one or more outer packagings, so that these elements are kept together and maintain the cross-sectional shape of the expectation of strip-shaped product.Preferably, packaging is made of paper.Packing can also include the adhesive that the overlapping free ends of packaging are adhered to each other.For example, far-front rod element, matrix element and the first tube element can be limited by the first packaging, and the second tube element and filter element can be limited by the second packaging.The second packaging can also limit at least a portion of the first tube element (after being wrapped by the first packaging) to be connected to the second tube element and filter element far-front rod element, matrix element and the first tube element limited by the first packaging.The second packaging can include the perforation around its circumference.

[0081] Further features and advantages of the aerosol-generating system and aerosol-generating article according to the invention have been described above in relation to the aerosol-generating device according to the invention and apply equally.

[0082] The invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

[0083] Example Ex1: An aerosol generating device for heating an aerosol-forming substrate capable of forming an inhalable aerosol when heated, the device comprising:

[0084] - a device housing comprising a cavity for removably receiving at least a portion of an aerosol-generating article, the article comprising the aerosol-forming substrate and an inductively heatable susceptor for heating the substrate, wherein the cavity comprises an insertion opening for inserting the article into the cavity;

[0085] a closure element reversibly movable relative to the device housing between a closed position, in which it covers the insertion opening, and an open position, in which the insertion opening is not blocked by the closure element;

[0086] - an induction heating device configured to generate an alternating magnetic field within the cavity for inductively heating a susceptor of the article when the article is received in the cavity;

[0087] a closure detector arranged and configured to detect at least one of: when the closure element is in the open position or when the closure element moves from the closed position to the open position; and

[0088] - a control circuit system operatively connected to the induction heating device and the closure detector and configured to

[0089] - energizing the induction heating device in response to a signal from the closure detector indicating that the closure element is in the open position or has moved from the closed position to the open position, respectively;

[0090] - determining at least one characteristic of the induction heating device or a change in at least one characteristic during energization of the induction heating device, the at least one characteristic being dependent on at least one of the type of the susceptor, the presence, absence, position and movement of the susceptor in the cavity; and

[0091] - detecting at least one specific state related to the product based on the determined characteristic or a change in the determined characteristic of the induction heating device.

[0092] Example Ex2: An aerosol generating device according to Example Ex1, wherein the control circuit system is configured to detect at least one of the type of product, insertion of the product, presence, absence, position and displacement of the product in the cavity based on the determined characteristic or change in the determined characteristic of the induction heating device.

[0093] Example Ex3: An aerosol generating device according to any of the preceding examples, wherein the control circuit system is configured to generate power pulses for intermittently powering the induction heating device, and determine at least one characteristic of the induction heating device or a change in the at least one characteristic during one or more power pulses.

[0094] Example Ex4: An aerosol generating device according to any of the preceding examples, wherein the closure detector is arranged and configured to further detect at least one of: when the closure is in the closed position or when the closure moves from the open position to the closed position.

[0095] Example Ex5: An aerosol generating device according to Example Ex4, wherein the control circuit system is configured to stop energizing the induction heating device in response to a signal from the closure detector indicating that the closure is in the closed position or when the closure moves from the open position to the closed position, respectively.

[0096] Example Ex6: An aerosol generating device according to any of the preceding examples, wherein the closure detector comprises one of a magnetic closure detector, an optical closure sensor, a capacitive closure detector, an inductive closure detector, and an electromechanical switch.

[0097] Example Ex7: An aerosol generating device according to Example Ex6, wherein, in order to detect when the closure is in the open position or when the closure moves from the closed position to the open position, the magnetic closure detector includes at least one magnetic sensor fixedly arranged in the device housing and at least one associated permanent magnet attached to the closure, so that the magnetic sensor senses the magnetic field of the associated permanent magnet when the closure is in the open position or moves to the open position, in particular only when the closure is in the open position.

[0098] Example Ex8: An aerosol generating device according to example Ex7, wherein when the closure is in the open position, the at least one magnetic sensor is arranged at a distance of at most 3 mm, in particular at most 2.5 mm, next to the at least one associated permanent magnet.

[0099] Example Ex9: An aerosol generating device according to any one of Examples Ex7 or 8, wherein when the closure is in the closed position, the at least one magnetic sensor is at least 5 mm, in particular at least 7.5 mm, preferably at least 10 mm, more preferably at least 15 mm away from the associated permanent magnet.

[0100] Example Ex10: An aerosol generating device according to Example Ex6, wherein the optical closure detector comprises a light sensor for detecting light, in particular ambient light, wherein the light sensor is arranged so as to be at least partially covered by the closure or a cover attached to or arranged at the closure when the closure is in the open position or in the closed position, respectively, and not blocked by the closure or a cover attached to or arranged at the closure when the closure is in the closed position or in the open position.

[0101] Example Ex11: An aerosol generating device according to Example Ex6, wherein the optical closure detector comprises a light emitter and a light receiver for sensing light emitted from the light emitter, wherein the light emitter and the light receiver are arranged so that light emitted from the light emitter toward the light receiver is blocked by the closure or a cover attached to the closure or arranged at the closure when the closure is in the open position or in the closed position, respectively, and is not blocked by the closure or the cover attached to the closure when the closure is in the closed position or in the open position.

[0102] Example Ex12: An aerosol generating device according to Example Ex6, wherein the electromechanical switch is activated by the closure member or an actuator attached to or arranged at the closure member when the closure member is in the open position or in the closed position, and is deactivated by the closure member or an actuator attached to the closure member when the closure member is in the closed position or in the open position.

[0103] Example Ex13: An aerosol generating device according to Example Ex6, wherein the electromechanical switch is activated by the closure member or an actuator attached to or arranged at the closure member when the closure member moves from the open position to the closed position or when the closure member moves from the closed position to the open position.

[0104] Example Ex14: An aerosol generating device according to Example Ex13, wherein the electromechanical switch is deactivated by the closure member or an actuator attached to or arranged at the closure member when the closure member moves from the closed position to the open position or when the closure member moves from the open position to the closed position.

[0105] Example Ex15: An aerosol generating device according to any one of Examples Ex1 to Ex14, wherein the closure is a sliding closure slidably guided on the device housing between the open position and the closed position.

[0106] Example Ex16: An aerosol generating device according to any one of Examples Ex1 to Ex14, wherein the closure is a pivoting closure pivotally mounted to the device housing.

[0107] Example Ex17: An aerosol generating device according to any one of Examples Ex1 to Ex14, wherein the closure is an iris diaphragm closure.

[0108] Example Ex18: An aerosol generating device according to any of the preceding examples, wherein the at least one characteristic or the change in at least one characteristic determined by the control circuit system is the current or the change in current supplied to the induction heating device.

[0109] Example Ex19: An aerosol generating device according to any of the preceding examples, wherein the control circuit system comprises a measuring device for measuring a current corresponding to or indicating at least one characteristic or a change in at least one characteristic of the induction heating device.

[0110] Example Ex20: An aerosol generating device according to any one of Example Ex18 or Example Ex19, wherein the control circuit system is configured to detect the presence of the receptor in the cavity when (or in response to) the current or the change in current supplied to the induction heating device violates or reaches a threshold, for example, when the current or the change in current exceeds or falls below a threshold.

[0111] Example Ex21: An aerosol generating device according to any of the preceding examples, wherein the control circuit system is configured to initiate a heating operation of the induction heating device in response to detecting insertion of the article into the cavity.

[0112] Example Ex22: An aerosol generating device according to any of the preceding examples, wherein the control circuit system is configured to disable a heating operation of the induction heating device in response to detecting the absence of an article in the cavity.

[0113] Example Ex23: An aerosol generating system, comprising an aerosol generating device according to any of the preceding examples and an aerosol generating article for use with the aerosol generating device, wherein the aerosol generating article is removably receivable in a cavity of the device and comprises at least one aerosol-forming substrate and at least one inductively heatable receptor, the at least one inductively heatable receptor being used to heat the substrate by interaction between the receptor and an alternating magnetic field provided by an inductive heating device of the device.

[0114] The present invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0115] Figure 1-2 schematically illustrates an exemplary embodiment of an aerosol generating system according to the present invention comprising an aerosol generating device and an aerosol generating article for use with the device;

[0116] Figure 3a -b shows the Figure 1 and Figure 2 an aerosol generating device of a system, wherein the closure member of the chamber is in a closed position;

[0117] Figure 4a -b shows the Figure 1 and Figure 2 an aerosol generating device of a system, wherein the closure of the chamber is in an open position;

[0118] Figure 5 Schematically shows the Figure 1 and Figure 2 An induction heating device for an aerosol generating device; and

[0119] Figure 6Shows Figure 5 Details of the pulse operation of the induction heating device shown in .

[0120] Figure 1 and Figure 2 An exemplary embodiment of an aerosol generating system 1 according to the invention is schematically shown, which is configured to generate an inhalable aerosol by heating an aerosol-forming substrate 21. The system 1 comprises: an aerosol-generating article 10 comprising the substrate 21 to be heated; and an elongated aerosol generating device 100 for heating the substrate 21 when the article 10 is engaged with the device 100.

[0121] like Figure 1 As can be seen in particular, the aerosol generating article 10 has a substantially strip shape similar to the shape of a conventional cigarette. In the present embodiment, the article 10 comprises five elements arranged in sequence in coaxial alignment: a distal front rod element 40, a matrix element 20, a first tube element 50, a second tube element 55, and a filter element 60 arranged at the proximal end of the article 10 and acting as a mouthpiece. The matrix element 20 comprises an aerosol-forming matrix 21 to be heated and an inductively heatable susceptor 30, which is in direct physical contact with the matrix 21 for heating the matrix 21 through the interaction of the susceptor 30 with an alternating magnetic field provided by the device 100. The inductive heating process will be described in more detail below. All of the aforementioned elements 20, 40, 50, 55 and 60 have a substantially cylindrical shape with substantially the same diameter. As Figure 1 and 2 As also shown in FIG. 1 , the five elements 20, 40, 50, 55 and 60 are defined by an outer wrapper 70 in order to hold the elements together and maintain the desired circular cross-sectional shape of the strip-like article 10. The wrapper 70 is preferably made of paper.

[0122] The aerosol generating device 100 comprises a device housing 101 comprising a cavity 103 within a proximal portion 102 of the device 100, the cavity being configured to removably receive at least a portion of an aerosol generating article 10. To insert the article 10 into the cavity 103, the device 100 comprises an insertion opening 105 at a proximal face of the device housing 101.

[0123] like Figure 1 and Figure 2 as well as Figure 3a , 3b and Figure 4a , 4b As shown in FIG. 1 , the aerosol generating device of this embodiment includes a closure member 107, which can be in a closed position relative to the device housing 101 (see FIG. 1 ). Figure 3a , 3b ) and open position (see Figure 4a ,4b as well as Figure 1 and Figure 2 ), in which the closure 107 covers the insertion opening 105, and in which the insertion opening 105 is not blocked by the closure 107. Advantageously, the closure 107 securely closes the cavity 103 and thus prevents debris from accidentally entering the cavity when no article 10 is present in the cavity 103, in particular when the device 100 is not in use. In this embodiment, the closure 107 is a sliding closure that is slidably guided on the device housing 101. To this end, the closure may include one or more guide members (not shown), each of which is slidably guided in a correspondingly formed guide groove 106 on the device housing 101 in a form-fitting manner.

[0124] Within the device housing 101 , the device 100 also includes a DC power supply 150 and a controller 160 for powering the device 100 and controlling the operation of the device.

[0125] To heat the substrate 21 in the article 10, the device 100 includes an induction heating device 110 that includes an induction coil 118 for generating a high frequency alternating magnetic field within the cavity 103. In the present embodiment, the induction coil 118 is a helical coil that is arranged in the proximal portion 102 of the device so as to circumferentially surround the cylindrical cavity 103. The coil 118 is arranged so that the susceptor 30 of the aerosol-generating article 10 is subjected to an electromagnetic field when the article 10 is engaged with the device 100. As described above, when the aerosol-generating article 10 is received in the cavity 103, the alternating magnetic field is used to inductively heat the susceptor 30 within the aerosol-generating article (see Figure 2 ). Thus, the alternating magnetic field may induce at least one of eddy currents and hysteresis losses in the susceptor 30, depending on the magnetic and electrical properties of the particular susceptor material(s). As a result, the susceptor 30 heats up until a temperature sufficient to vaporize the aerosol-forming substrate 21 surrounding the susceptor 30 within the article 10 is reached.

[0126] The system is configured so that when the article 10 is inserted into the cavity 103 and when the heating means 110 is activated, the user can draw on the filter element 60, whereby air is drawn into the cavity 103 at the edge of the insertion opening 105. The airflow further extends towards the distal end of the cavity 103 along a channel formed between the inner surface of the cylindrical cavity 103 and the outer surface of the cylindrical article 10. At the distal end of the cavity 103, the airflow enters the aerosol-generating article 10 through the distal front rod element 40 and further passes through the matrix element 20, the first tube element 50, the second tube element 55 and the filter element 60, where it finally exits the article 10 into the mouth of the user. Thus, during operation of the device, vaporized material from the aerosol-forming substrate 21 may be entrained in the airflow passing through the matrix element 20. Subsequently, the airflow comprising the vaporized material cools while passing through the first tube element 50, the second tube element 55 and the filter element 60 so as to form an aerosol that escapes the article 10 through the filter element 60.

[0127] Figure 5 1 shows further details of the induction heating device 110. According to the present embodiment, the induction heating device 110 comprises a DC / AC inverter connected to Figure 1 and 2 The DC power supply 150 shown in FIG. The DC / AC inverter includes a class E power amplifier including the following components: a transistor switch 111 including a field effect transistor T (FET), such as a metal oxide semiconductor field effect transistor (MOSFET); a transistor switch supply circuit, indicated by arrow 112, for supplying a switching signal (gate-source voltage) to the transistor switch 111; and an LC load network 113 including a shunt capacitor C1 and a series connection of a capacitor C2 and an inductor L2. The inductor L2 corresponds to Figure 1 and 2 The induction coil 118 shown in FIG. 1 is used to generate an alternating magnetic field in the cavity 103. In addition, a choke L1 supplied with a DC power supply voltage +V_DC from a DC power supply 150 is provided. Figure 5 Also shown is an ohmic resistance R representing a total equivalent resistance or total resistive load 114, which is the sum of the ohmic resistance of the inductor coil 118, referenced as L2, and the ohmic resistance of the susceptor when the system is in use, i.e. when an article is inserted into the cavity 103 of the device 100. Otherwise, in the case where an article is not inserted into the cavity 103, the equivalent resistance or resistive load 114 corresponds only to the ohmic resistance of the inductor coil 118. Further details of the induction heating device 110 according to the present embodiment, in particular with regard to its operating principle, are disclosed, for example, in WO 2015 / 177046A1.

[0128] For various purposes, in particular for automatically starting or for disabling the heating process, it may be necessary to detect certain states related to the aerosol-generating article to be received in the cavity 103. Such states may be, for example, the type of article, the insertion of the article, the presence, absence, position or displacement of the article in the cavity 103. According to the invention, such state detection is achieved via the heating device 110, which advantageously enables to avoid additional assembly space for a separate sensor device. The basic idea for detecting one or more of these states is to detect at least one characteristic or a change in at least one characteristic of the inductive heating device 110, which depends on at least one of the type of susceptor 30 of the article 10, the presence, absence, position and movement of the susceptor in the cavity 103. In the present embodiment, the total resistive load 114 of the heating device 110 is used as a characteristic of the inductive heating device, which in particular indicates the presence or absence of the article 10 in the cavity 103. As explained above, the value of the total equivalent resistance or total resistive load 114 depends on the presence or absence of the susceptor 30 in the vicinity of the induction coil 118. The total equivalent resistance 118 corresponds to the sum of the ohmic resistance of the inductor coil 118 and the ohmic resistance of the susceptor 30 when the article is inserted into the cavity 103 of the device 100 , and corresponds only to the ohmic resistance of the inductor coil 118 when the article is not received in the cavity 103 .

[0129] This change in the equivalent resistance 118 can be detected by supplying a DC current I_DC from a DC power supply 150 to the induction heating device 110, i.e. to the LC load network 113. To this end, the aerosol generating device comprises a current measuring device 140 arranged in series connection between the DC power supply 150 and the LC load network 113 (see Figure 5 ). Therefore, when the aerosol generating article 10 is inserted into the cavity 103 of the device 100, the presence of the susceptor 30 increases the equivalent resistance 118 of the heating device due to the increased resistive load 114 by the presence of the susceptor 30. This in turn leads to a reduction in the DC current feeding the induction heating device 110. The reduction in the DC current I_DC is detected by the current measuring device 140, which can then be used as a trigger signal to start a heating operation for heating the substrate 21. Vice versa, when the aerosol generating article 10 is withdrawn from the cavity 103, the absence of the susceptor 30 is associated with a lower value of the equivalent resistance 118 of the heating device 110 due to the reduced resistive load 114 by the absence of the susceptor 30. This in turn leads to a lower value of the DC current feeding the induction heating device 110. The current measuring device 140 can detect the reduction and increase ΔI_DC of the DC current or the corresponding higher value I_NA or lower value I_A (see Figure 6 ).

[0130] In order to reduce the total power consumption when the aerosol generating device 100 is in the state detection mode, the heating assembly is preferably operated not in a continuous mode but in a pulsed mode. To this end, the device 100 according to the present embodiment comprises a switch 130, which is arranged and configured to control the power supply from the DC power supply 150 to the induction heating device 110. Figure 5 As can be seen in FIG. 1 , the switch 130 is arranged in series connection between the DC power supply 150 and the LC load network 113. During state detection, the switch 130 is intermittently opened and closed to generate power pulses for intermittently powering on the induction heating device 110. During subsequent heating operation, the switch 130 may be permanently closed to continuously apply the DC voltage of the DC power supply to the induction heating device 110 to continuously heat the susceptor 30. Alternatively, the switch 130 may be intermittently closed and opened during the heating operation to generate heating power pulses for pulsed heating of the susceptor 30.

[0131] As also shown in FIG. 3 , the switch 130 and the current measuring device 140 are both part of a control circuit system, which also includes a microprocessor 160. The microprocessor 160 is configured to control the switch 130 so as to generate a power pulse; read the measuring device 140 for measuring the current I_DC supplied from the DC power supply to the induction heating device 110; and control the transistor switch driver circuit 112. The control circuit system may be part of the overall controller of the aerosol generating device 100 or may be the overall controller of the aerosol generating device. During the state detection, the microprocessor 160 starts driving the switch by closing the switch 130 for a predetermined closing time interval, thereby generating a current pulse having a pulse duration T1 corresponding to the closing time interval. The pulse duration T1 may be in the range between 1 microsecond and 500 microseconds, in particular between 10 microseconds and 300 microseconds, preferably between 15 microseconds and 120 microseconds, and most preferably between 30 microseconds and 100 microseconds. At the end of the closing time interval, the microprocessor 160 opens the switch 130 again within a predetermined opening time interval, thereby interrupting the current path to the heating device 110. The open time interval corresponds to the time interval between two consecutive power pulses. For product detection, the open time interval can be between 50 milliseconds and 2 seconds, in particular between 100 milliseconds and 2 seconds, preferably in the range of 500 milliseconds and 1 second. The closing and opening of the switch 130 can be performed at regular time intervals so as to generate periodic power pulses for periodically powering on the induction heating device 110. Therefore, the sum of the closing time interval and the opening time interval, or the sum of the pulse duration and the time interval between two consecutive power pulses corresponds to the period of the pulse series. In general, the time interval between two consecutive detection power pulses T2 should be selected so as to balance the impact of energy consumption and user experience performance. The pulse duration T1 should be kept as minimal as possible, but provide reliable measurement of the current pulse.

[0132] Figure 6is an exemplary embodiment showing a series of current pulses I_DC over time t, wherein the pulse duration T1 is 100 microseconds and the time interval T2 between two consecutive power pulses is 1 second. It should be understood that these values ​​are exemplary only and may vary. As long as no aerosol generating article is inserted, the current measuring device 140 measures a current having a value I_NA (wherein "NA" means "no article") for each pulse. As explained, the measured value I_NA depends on the ohmic load 114, which is equal to the ohmic resistance of the inductor L2. In contrast, when the user inserts the article 10 into the cavity 103, the ohmic load 114 increases because the ohmic load is now equal to the ohmic resistance of the inductor L2 and the ohmic resistance of the susceptor 30. Due to the increase in the ohmic load, the current absorbed by the heating assembly decreases. Therefore, the current measuring device 140 measures a current pulse having a value I_A (wherein "A" means "article inserted"), which is lower than I_NA. The difference ΔI_DC between I_NA and I_A is registered by the microcontroller 160 which triggers the start of the heating mode.

[0133] According to the present invention, it has been found that any state detection involving the heating device 110 consumes the least amount of energy if it is actively powered on only when the state detection is actually needed. Typically, the state detection is mainly needed at the beginning of the user experience shortly before the actual heating operation of the device 100, that is, when the heating device 110 is not actually functional yet but is about to be used. In order to provide a suitable trigger for activating the state detection, the present invention proposes to use the position and / or movement of the closure 107, in particular the open position and / or the movement to the open position, because this is a very suitable indication for the beginning of the user experience. Vice versa, the closure 107 that closes the cavity can be a very suitable indication that the user experience ends, and therefore can be a very suitable trigger for stopping the heating operation of the device. Advantageously, the use of the position and / or movement of the closure 107 as a trigger does not require any additional interaction of the user with the device, such as pressing a button. On the contrary, in any case, this trigger advantageously utilizes the action taken by the user at the beginning or end of the user experience.

[0134] In order that the position and / or movement of the closure 107 can be used as a trigger, the aerosol generating device 100 comprises a closure detector 108 arranged and configured to detect at least one of the following: when the closure 107 is in the open position or when the closure 107 moves from the closed position to the open position. The closure detector 108 is operably connected to the control circuit system of the device 100, which in turn is configured to initiate state detection by energizing the induction heating device 110 in response to a signal from the closure detector 108 indicating that the closure is in the open position or moves from the closed position to the open position, respectively.

[0135] In the present embodiment, the closure detector 108 is a magnetic closure detector 108, which includes a permanent magnet 108a attached to the closure member 107 and a magnetic sensor 108b fixedly arranged in the device housing 101, so that when the closure member 107 is in the open position or moves to the open position (see Figure 4a and Figure 4b ), the magnetic sensor 108b senses the magnetic field of the permanent magnet 108a. In particular, the permanent magnet 108a and the magnetic sensor 100b can be arranged so that the magnetic sensor 100b senses the magnetic field of the permanent magnet 108a only when the closure 107 is in the open position. Advantageously, this arrangement ensures that the opening can be detected reliably, in particular without external interference. In order to ensure such interference-free detection, when the closure 107 is in the open position, the permanent magnet 108a is preferably arranged next to the magnetic sensor 108b at a distance of at most 3 mm, in particular at most 2.5 mm (see Figure 4a and Figure 4b Vice versa, when the closure member 107 is in the closed position, the permanent magnet 108a is preferably at least 40 mm away from the magnetic sensor 108b (see Figure 3a and Figure 3b ).

[0136] For the purposes of this specification and the appended claims, unless otherwise stated, all numbers representing amounts, quantities, percentages, etc. should be understood to be modified by the term "about" in all cases. Moreover, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein that may or may not be specifically listed herein. Therefore, in this context, the number A is understood to be A±5%A. In this context, the number A may be considered to include a value within the general standard error for the measurement of the property modified by the number A. In certain cases used in the appended claims, the number A may deviate from the percentages listed above, provided that the amount of A deviation does not substantially affect the basic and novel features of the claimed invention. Moreover, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein that may or may not be specifically listed herein.

Claims

1. An aerosol generating device for heating an aerosol-forming substrate capable of forming an inhalable aerosol when heated, the device comprising: a device housing comprising a cavity for removably receiving at least a portion of an aerosol-generating article, the article comprising the aerosol-forming substrate and an inductively heatable susceptor for heating the substrate, wherein the cavity comprises an insertion opening for inserting the article into the cavity; a closure member reversibly movable relative to the device housing between a closed position in which the closure member covers the insertion opening and an open position in which the insertion opening is not blocked by the closure member; an induction heating device configured to generate an alternating magnetic field within the cavity for inductively heating a susceptor of the article when the article is received in the cavity; a closure detector arranged and configured to detect at least one of: when the closure member is in the open position or when the closure member moves from the closed position to the open position; as well as a control circuit system operatively connected to the induction heating device and the closure detector and configured to - energizing the induction heating device in response to a signal from the closure detector indicating that the closure element is in the open position or has moved from the closed position to the open position, respectively; - determining at least one characteristic of the induction heating device or a change in at least one characteristic during energization of the induction heating device, the at least one characteristic depending on at least one of the type of the susceptor, the presence, absence, position and movement of the susceptor in the cavity; as well as - detecting at least one specific state related to the product based on the determined characteristic or a change in the determined characteristic of the induction heating device.

2. An aerosol generating device according to claim 1, wherein the control circuit system is configured to detect at least one of the type of article, insertion of the article, presence, absence, position and displacement of the article in the cavity based on the determined characteristic or change in the determined characteristic of the induction heating device.

3. An aerosol generating device according to any of the preceding claims, wherein the control circuit system is configured to generate power pulses for intermittently powering the induction heating device, and to determine the at least one characteristic or a change in the at least one characteristic of the induction heating device during one or more power pulses.

4. An aerosol generating device according to any one of the preceding claims, wherein the closure detector is arranged and configured to further detect at least one of: when the closure member is in the closed position or when the closure member moves from the open position to the closed position.

5. An aerosol generating device according to claim 4, wherein the control circuit system is configured to stop energizing the induction heating device in response to a signal from the closure detector indicating that the closure member is in the closed position or when the closure member moves from the open position to the closed position, respectively.

6. An aerosol generating device according to any one of the preceding claims, wherein the closure detector comprises one of a magnetic closure detector, an optical closure sensor, a capacitive closure detector, an inductive closure detector and an electromechanical switch.

7. An aerosol generating device according to claim 6, wherein, in order to detect when the closure is in the open position or when the closure moves from the closed position to the open position, the magnetic closure detector comprises at least one magnetic sensor fixedly arranged in the device housing and at least one associated permanent magnet attached to the closure, so that the magnetic sensor senses the magnetic field of the associated permanent magnet when the closure is in the open position or moves to the open position, in particular only when the closure is in the open position.

8. An aerosol generating device according to claim 7, wherein when the closure is in the open position, the at least one magnetic sensor is arranged at a distance of at most 3 mm, in particular at most 2.5 mm, in close proximity to the at least one associated permanent magnet; and / or wherein when the closure is in the closed position, the at least one magnetic sensor is at least 5 mm, in particular at least 7.5 mm, preferably at least 10 mm, more preferably at least 15 mm away from the associated permanent magnet.

9. An aerosol generating device according to claim 6, wherein the optical closure detector comprises a light sensor for detecting light, in particular ambient light, wherein the light sensor is arranged so as to be at least partially covered by the closure or a cover attached to or arranged at the closure when the closure is in the open position or in the closed position, respectively, and not blocked by the closure or a cover attached to or arranged at the closure when the closure is in the closed position or in the open position.

10. An aerosol generating device according to claim 6, wherein the optical closure detector comprises a light emitter and a light receiver for sensing light emitted from the light emitter, wherein the light emitter and the light receiver are arranged so that light emitted from the light emitter toward the light receiver is blocked by the closure or a cover attached to or arranged at the closure when the closure is in the open position or in the closed position, respectively, and is not blocked by the closure or the cover attached to the closure when the closure is in the closed position or in the open position.

11. An aerosol generating device according to claim 6, wherein the electromechanical switch is activated by the closure member or an actuator attached to or arranged at the closure member when the closure member is in the open position or in the closed position, respectively, and is deactivated by the closure member or an actuator attached to the closure member when the closure member is in the closed position or in the open position.

12. An aerosol generating device according to claim 6, wherein the electromechanical switch is activated by the closure member or an actuator attached to or arranged at the closure member when the closure member moves from the open position to the closed position or when the closure member moves from the closed position to the open position; and wherein preferably, the electromechanical switch is deactivated by the closure member or an actuator attached to or arranged at the closure member when the closure member moves from the closed position to the open position or when the closure member moves from the open position to the closed position.

13. An aerosol generating device according to any one of the preceding claims, wherein the closure is one of: - a sliding closure which is slidably guided on the device housing between the open position and the closed position; - a pivoting closure member pivotally mounted to the device housing; -Iris type aperture closure.

14. An aerosol generating device according to any one of the preceding claims, wherein the control circuitry is configured to perform at least one of the following: - initiating a heating operation of the induction heating device in response to detecting insertion of an article into the cavity; - disabling heating operation of the induction heating device in response to detecting the absence of an article in the cavity.

15. An aerosol generating system, comprising an aerosol generating device according to any of the preceding claims and an aerosol generating article for use with the aerosol generating device, wherein the aerosol generating article is removably received in a cavity of the device and comprises at least one aerosol-forming substrate and at least one inductively heatable receptor, the at least one inductively heatable receptor being used to heat the substrate by interaction between the receptor and an alternating magnetic field provided by an inductive heating device of the device.

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